Green Chemistry Approaches to Environmental Sustainability: Status, Challenges and Prospective 9780443189609, 0443189609

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GREEN CHEMISTRY APPROACHES TO ENVIRONMENTAL SUSTAINABILITY

Advances in Green and Sustainable Chemistry

GREEN CHEMISTRY APPROACHES TO ENVIRONMENTAL SUSTAINABILITY Status, Challenges and Future Perspectives Edited by

VINOD KUMAR GARG Department of Environmental Science and Technology, Central University of Punjab, Bathinda, Punjab, India

ANOOP YADAV Department of Environmental Studies, Central University of Haryana, Mahendergarh, Haryana, India

CHANDRA MOHAN Department of Chemistry, School of Basic and Applied Sciences, K. R. Mangalam University, Gurugram, Haryana, India

SUSHMA YADAV Industrial Waste Management, Department of Vocational Studies and Skill Development, Central University of Haryana, Mahendergarh, Haryana, India

NEERAJ KUMARI Department of Chemistry, School of Basic and Applied Sciences, K. R. Mangalam University, Gurugram, Haryana, India

Series Editors

BELA TOROK TIMOTHY DRANSFIELD

Elsevier Radarweg 29, PO Box 211, 1000 AE Amsterdam, Netherlands The Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, United Kingdom 50 Hampshire Street, 5th Floor, Cambridge, MA 02139, United States Copyright © 2024 Elsevier Inc. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions. This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). Notices Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. ISBN: 978-0-443-18959-3 For Information on all Elsevier publications visit our website at https://www.elsevier.com/books-and-journals

Publisher: Candice Janco Acquisitions Editor: Charles Bath Editorial Project Manager: Dan Egan Production Project Manager: Bharatwaj Varatharajan Cover Designer: Greg Harris Typeset by MPS Limited, Chennai, India

Contents 2.2.11 Effect of noise pollution 32 2.2.12 Possible solutions 33 2.2.13 Plastic pollution 33 2.2.14 Effects of plastic pollution 34 2.2.15 Possible solutions 34 2.2.16 Soil pollution 35 2.2.17 Effects of soil pollution 35 2.2.18 Possible solutions 36 2.2.19 Light pollution 36 2.2.20 Effects of light pollution 37 2.2.21 Possible solutions 37 2.3 Switching to sustainable energy “a requirement for the safer environment” 2.4 Conclusion 39 References 39

List of contributors xi 1. Introduction to environmental and green chemistry 1 Sushma Yadav, Anoop Yadav, Chandra Mohan, Vinod Kumar Garg and Neeraj Kumari

1.1 Introduction to environmental chemistry 1 1.1.1 Origin and evolution of earth 2 1.1.2 Formation of the crust and atmosphere 2 1.1.3 Origin of life and atmosphere 2 1.2 Environmental chemistry 3 1.2.1 Importance of environmental chemistry 3 1.2.2 Contamination and pollution 4 1.3 Introduction to green chemistry 5 1.4 History and origin of green chemistry 6 1.4.1 Synthetic chemistry and green chemistry 7 1.4.2 Need of the green chemistry 8 1.4.3 Basic principles of green chemistry 9 1.4.4 Future challenges 18 1.5 Conclusion 19 References 19

3. Toxicity of polyaromatic hydrocarbons and their biodegradation in the environment 43 Shanky Jindal, Yogita Chaudhary and Kamal Krishan Aggarwal

3.1 Introduction 43 3.2 Polycyclic aromatic hydrocarbons in the environment 49 3.3 Toxicity of polycyclic aromatic hydrocarbons 50 3.3.1 Toxicity in environmental matrices 50 3.3.2 Toxicity on humans 51 3.3.3 Toxicity of polycyclic aromatic hydrocarbons on birds, amphibians and aquatic animals 53 3.3.4 Toxicity of polycyclic aromatic hydrocarbons on plants 54 3.4 Bioremediation of polycyclic aromatic hydrocarbons 57 3.4.1 Bioaugmentation 58 3.4.2 Biostimulation 58 Acknowledgement 59 References 59 Further reading 65

2. Environmental pollution 23 Nidhi Gaur, Swati Sharma and Nitin Yadav

2.1 Introduction 23 2.2 Types of pollution and its causes 25 2.2.1 Air pollution 25 2.2.2 Effects of air pollution 26 2.2.3 Possible solutions 27 2.2.4 Water pollution 28 2.2.5 Effect of water pollution 29 2.2.6 Possible solutions 29 2.2.7 Radioactive pollution 30 2.2.8 Effects of radioactive pollution 2.2.9 Possible solutions 31 2.2.10 Noise pollution 31

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4. Application of green chemistry for environmental remediation 67 Manoj Kumar Banjare, Kamalakanta Behera, Ramesh Kumar Banjare, Mamta Tandon, Siddharth Pandey and Kallol K. Ghosh

4.1 4.2 4.3 4.4

Introduction 67 History 68 Concept of green chemistry 69 Ionic liquids 69 4.4.1 Characteristics of ionic liquids 71 4.5 Water as a solvent for organic reactions 73 4.6 The benefits of green chemistry 74 4.7 Twelve principles of green chemistry 75 4.8 Green and sustainable chemistry is gaining ground 75 4.9 Opportunities for green and sustainable chemistry 75 4.10 Most efficient method for addressing a variety of environmental problems 75 4.11 Water treatments 76 4.12 Advantages of green chemistry 77 4.12.1 Human health 77 4.12.2 Environment 78 4.12.3 Economy and business 78 4.13 Green chemistry in day-to-day life 78 4.14 Green solution to turn turbid water clear 80 4.15 The three primary environmental restoration and cleanup methods 80 4.16 Soil remediation 80 4.17 Groundwater and surface water remediation 82 4.18 Remediation of sediments 83 4.19 Environmental remediation 83 4.19.1 Environmental remediation steps 84 4.19.2 Environmental sedimentation technologies 85 4.20 Conclusions 87 Acknowledgements 88 Notes 88 Authors contribution 88 References 88

5. Approaches and challenges with respect to green chemistry in industries 93 Suneeta Bhandari, Akansha Agrwal and Munni Bhandari

5.1 Introduction 93 5.2 Green chemistry’s impact

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5.3 History of green chemistry 94 5.3.1 Green chemistry 94 5.3.2 Twelve principles of green chemistry 95 5.4 Challenges for chemists 96 5.5 Application of green chemistry in industry 97 5.6 Greener pharmaceutical industries 97 5.7 Greener solvents 99 5.8 Bio-based modifications and resources 100 5.9 Green synthesis 101 5.10 Alternative renewable energy science 102 5.10.1 Photovoltaic solar energy 102 5.11 Challenges in research 104 5.12 Conclusion 105 References 105

6. Full blown green metrics 109 Payal B. Joshi, Nivedita Chaubal-Durve and Chandra Mohan

6.1 Introduction 109 6.1.1 Motivation and goal of the chapter 111 6.2 Greening of industrial synthesis: a compelling necessity 111 6.2.1 Are waste metrics reliable? 111 6.2.2 Current industrial processes and metrics 114 6.3 Overview on green analytical chemistry 115 6.3.1 Developed green analytical metrics 117 6.3.2 March towards miniaturization 120 6.3.3 Bio-based solvents in synthesis and analysis 121 6.4 Sustainability metrics 122 6.5 Conclusions and future perspectives 124 Abbreviations 125 References 126

7. Green anthrosphere through industrial ecology 131 Manik Devgan, Arshdeep Kaur, Anuj Choudhary, Radhika Sharma, Harmanjot Kaur and Sahil Mehta

7.1 Introduction 131 7.2 Infrastructure and sociosphere of anthrosphere 132 7.3 Impact of IE on the environment 7.4 Green chemistry and IE 135

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7.4.1 Risk pruning 136 7.4.2 Heavy metals 136 7.4.3 Hydrocarbons 136 7.4.4 Corrosive compounds 136 7.4.5 Green chemicals 137 7.4.6 Catalysts 137 7.4.7 Feedstock 138 7.4.8 Solvents 139 7.4.9 Chemical/reagents 140 7.5 Industrial ecosystems design to reduce the environmental impact 140 7.6 Policies and paradigm for the GE 141 7.7 Conclusions 141 References 143

8. Plant-derived compounds and their green synthesis in pharmaceuticals and nutraceuticals 149 Babita, Vandana Singh and Chandra Mohan

8.1 Introduction 149 8.2 Plant-derived nanoparticles in pharmaceuticals 152 8.2.1 Therapeutic applications 152 8.3 Antibacterial activity 152 8.4 Anti-inflammatory activity 154 8.5 Anticancer role 155 8.6 Antiviral role against COVID-19 155 8.7 Plant-derived nanostructures in nutraceuticals formulation 155 8.8 Conclusion 157 References 158

9. Radioactive waste minimization and management 165 Pradeep Kumar, Sushma Yadav and Anoop Yadav

9.1 Introduction 165 9.2 Sources of nuclear wastes 167 9.2.1 Mining and milling of uranium 167 9.2.2 Processing of uranium oxides 167 9.2.3 Fuel fabrication 168 9.2.4 Reactor wastes 168 9.2.5 Spent fuel processing 169 9.3 Disposal guidelines 172 9.3.1 Isolation and concentration 172 9.3.2 Dispersion and dilution 173

9.3.3 Delay and decay 173 9.4 Disposal methods 173 9.4.1 Storage of liquid and solid wastes 174 9.4.2 Evaporation 174 9.4.3 Precipitation and flocculation 175 9.4.4 Ion exchange 175 9.4.5 Glass fixation 176 9.5 Fracturing of rocks 176 9.5.1 Salt mines 177 9.5.2 Solids 177 9.5.3 Conditioning 178 9.6 Protection and radiation control 179 9.6.1 Maximum allowable dose for radiation protection 179 9.6.2 Radiation protection precautions 179 9.6.3 Radiation-based regulation 180 9.6.4 Limiting workplace radiation exposure 181 9.6.5 Security 181 9.6.6 Defence against fire 182 9.6.7 Defence against insects and rodents 182 9.6.8 Protection from high temperatures 183 9.7 Conclusion 183 References 183

10. Renewable and sustainable energy from CO2 following the green process 185 Shashank Bahri, Sreedevi Upadhyayula and Firdaus Parveen

10.1 Introduction 185 10.2 Sustainable and renewable energy from CO2 derived renewable biomass 186 10.2.1 Composition of syngas 187 10.2.2 Plausible reaction networks 188 10.2.3 Product distribution during the process 190 10.2.4 Possibilities of using low Ribblet ratio syngas in Fischer-Tropsch reaction 191 10.2.5 Enriching the energy value for liquid product 193 10.3 Catalysts for sustainable conversion of CO2 to energy 194 10.3.1 Bimetallic catalyst composition 195 10.3.2 Structural activity relationship 199

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10.3.3 Deactivation behaviour of Fe-Co bimetallic catalyst 199 10.3.4 Catalyst for low Ribblet ratio syngas 200 10.4 Reaction mechanics and kinetics 203 10.4.1 Fischer-Tropsch mechanism 203 10.4.2 Fischer-Tropsch kinetics 205 10.5 Conclusion 210 References 211

11. Use of renewable feedstocks for chemical synthesis 219 Shivani Verma, Sanjeev Verma, Akansha Agrwal and Saurabh Kumar

11.1 Introduction 219 11.2 Green chemistry 221 11.3 Renewable feedstocks and renewable energy 223 11.4 Requirements of renewable and sustainable feedstocks 224 11.5 Renewable feedstock as catalytic system 225 11.6 Different renewable resources used in organic synthetic chemistry 226 11.6.1 Using heterogeneous catalytic system 226 11.6.2 Using bioproducts 229 11.6.3 Using natural products 230 11.7 Advantages of renewability factors in organic synthesis 232 11.8 Future challenges and outlooks 232 11.9 Conclusion 232 References 233

12. A green approach: living nanofactories 239 Vandana Singh and Babita

12.1 Introduction 239 12.2 Biological nanofactories 243 12.2.1 Bacteria 243 12.3 Applications of biologically synthesized nanoparticles 252 12.4 Factors affecting nanoparticle synthesis 253 12.5 Future prospects 256 12.6 Conclusion 256 References 257

13. Green energy and green fuels technologies 261 Ranjan Kumar Basak and Ashish Kumar Asatkar

13.1 Introduction 261 13.2 Green fuels 262 13.2.1 Solar energy 262 13.2.2 Wind energy 269 13.2.3 Geothermal power 274 13.2.4 Wave energy 280 13.2.5 Tidal energy 287 13.2.6 Hydroelectricity 289 13.2.7 Biodiesel 291 13.2.8 Gasohol 294 13.2.9 Biogas power 296 13.2.10 Hydrogen fuel 297 13.2.11 Fuel cells 301 13.3 Conclusion 307 References 308

14. Green approaches for the valorization of olive mill wastewater 313 Pawan Kumar Rose, Mohd. Kashif Kidwai and Pinky Kantiwal

14.1 Introduction 313 14.2 OMWW: production and characteristics 314 14.3 Green approaches for OMWW treatment 316 14.3.1 AD 316 14.3.2 Composting 320 14.3.3 Vermicomposting 322 14.4 Biovalorization of OMWW into biofuel 324 14.4.1 Bioethanol 324 14.4.2 Biodiesel 325 14.4.3 Biohydrogen 326 14.4.4 Biomethane 328 14.5 Concluding remarks and future prospects 329 References 331

15. Depolymerization of waste plastics and chemicals 337 Archana Kumari, Sarmistha Debbarma, Prabhakar Maurya and Vivek Anand

15.1 Introduction 337 15.2 Plastic and their classifications 338 15.2.1 Natural plastics 338 15.2.2 Semisynthetic plastics 339

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15.2.3 Synthetic plastics 339 History of plastics 340 Harmful effects of plastic waste 341 Complexity associated with plastic waste 341 Management strategies to control plastic waste pollution 342 15.6.1 Recycling 343 15.6.2 Landfills 344 15.6.3 Bioremediation 345 15.6.4 Upcycling by depolymerization 345 15.6.5 Polymerization 348 15.6.6 Bioplastics 349 15.6.7 Bio-based additives 350 15.6.8 Microplastics 351 15.7 Conclusion 352 References 352 15.3 15.4 15.5 15.6

16. Sustainable Development Goals for addressing environmental challenges 357 Chandra Mohan, Jenifer Robinson, Lata Vodwal and Neeraj Kumari

16.1 Introduction 357 16.2 Sustainable management of clean water and sanitation 358

16.3 Ensuring access to sustainable energy 359 16.3.1 Building sustainable chemistry to combat climate change 360 16.3.2 Building a sustainable ecosystem on land 361 16.3.3 Building a sustainable ecosystem in the water 363 16.3.4 Ensuring the availability of cleaner fuel choices 363 16.3.5 Building next-generation energy sources 364 16.4 Bioremediation and phytoremediation 369 16.4.1 Advantages of bioremediation and phytoremediation 370 16.5 Application of biotechnology in achieving Sustainable Development Goals and mitigating environmental challenges 371 16.6 Case studies 371 16.7 Conclusion 372 References 372

Index 375

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List of contributors Suneeta Bhandari Organic Synthesis Laboratory, Department of Chemistry, G. B. Pant University of Agriculture and Technology, U.S. Nagar, Uttarakhand, India

Kamal Krishan Aggarwal University School of Biotechnology, Guru Gobind Singh Indraprastha University, New Delhi, India Akansha Agrwal Department of Applied Sciences, KIET Group of Institutions, DelhiNCR, Ghaziabad, Uttar Pradesh, India

Nivedita Chaubal-Durve Department of Basic Sciences, Mukesh Patel School of Technology Management and Engineering SVKMs NMIMS, Mumbai, Maharashtra, India

Vivek Anand Department of Chemistry, University Institute of Science, Chandigarh University, Gharuan, Mohali, Punjab, India

Yogita Chaudhary University School of Biotechnology, Guru Gobind Singh Indraprastha University, New Delhi, India

Ashish Kumar Asatkar Department of Chemistry, Satyanarayan Agarwal Govt. Arts & Commerce College, Kohka-Newra (Tilda), Dist. Raipur, Chhattisgarh, India

Anuj Choudhary Department of Biology and Environmental Sciences, CSKHPKV, Palampur, Himachal Pradesh, India

Babita Department of Pharmacology, School of Allied Health Sciences, Sharda University, Gr. Noida, Uttar Pradesh, India

Sarmistha Debbarma Animal Resources Development Department, Gurkhabusti, Tripura, India

Shashank Bahri Heterogeneous Catalysis and Reaction Engineering Laboratory, Department of Chemical Engineering, Indian Institute of Technology Delhi, New Delhi, India

Manik Devgan Department of Plant Breeding and Genetics, Punjab Agricultural University, Ludhiana, Punjab, India Vinod Kumar Garg Department of Environmental Science and Technology, Central University of Punjab, Bathinda, Punjab, India

Manoj Kumar Banjare MATS School of Sciences, MATS University, Pagaria Complex, Raipur, Chhattisgarh, India; School of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur, Chhattisgarh, India

Nidhi Gaur D.A.V Public School, Gurugram, Haryana, India

Ramesh Kumar Banjare Department of Chemistry (MSET), MATS University, Gullu Campus, Raipur, Chhattisgarh, India

Kallol K. Ghosh School of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur, Chhattisgarh, India

Ranjan Kumar Basak Department of Chemistry, Shivharsh Kisan P.G. College Basti, Basti, Uttar Pradesh, India

Shanky Jindal University School of Biotechnology, Guru Gobind Singh Indraprastha University, New Delhi, India

Kamalakanta Behera Department of Chemistry, University of Allahabad, Prayagraj, Uttar Pradesh, India

Payal B. Joshi Department of Basic Sciences, Mukesh Patel School of Technology Management and Engineering SVKMs NMIMS, Mumbai, Maharashtra, India; Operations and Method Development, Shefali Research Laboratories, Mumbai, Maharashtra, India

Munni Bhandari Department of Microbiology, H.N.B. Garhwal University, Srinagar Garhwal, Uttarakhand, India

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Pinky Kantiwal Department of Vocational Studies and Skill Development, Central University of Haryana, Mahendergarh, Haryana, India Arshdeep Kaur Department of Plant Breeding and Genetics, Punjab Agricultural University, Ludhiana, Punjab, India Harmanjot Kaur Department of Botany, Punjab Agricultural University, Ludhiana, Punjab, India Mohd. Kashif Kidwai Department of Energy and Environmental Sciences, Chaudhary Devi Lal University, Sirsa, Haryana, India Pradeep Kumar Industrial Waste Management, Department of Vocational Studies and Skill Development, Central University of Haryana, Mahendergarh, Haryana, India Saurabh Kumar Department of Electronics and Communication Engineering, NIT Hamirpur, Hamirpur, Himachal Pradesh, India Archana Kumari Shriram Institute Industrial research, New Delhi, India

for

Neeraj Kumari Department of Chemistry, School of Basic and Applied Sciences, K. R. Mangalam University, Gurugram, Haryana, India Prabhakar Maurya Consultancy for Environmental & Human Toxicology and Risk Assessment (Fr), India Office, New Delhi, India Sahil Mehta Department of Botany, Hansraj College, University of Delhi, New Delhi, Delhi, India Chandra Mohan Department of Chemistry, School of Basic and Applied Sciences, K. R. Mangalam University, Gurugram, Haryana, India Siddharth Pandey Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, Delhi, India

Firdaus Parveen Department of Chemistry, University of Liverpool, Liverpool, United Kingdom Jenifer Robinson Department of Science and French, Indian School Al Wadi Al Kabir, Muscat, Sultanate of Oman Pawan Kumar Rose Department of Energy and Environmental Sciences, Chaudhary Devi Lal University, Sirsa, Haryana, India Radhika Sharma Department of Soil Science, Punjab Agricultural University, Ludhiana, Punjab, India Swati Sharma Department of Physics, University of Rajasthan, Jaipur, Rajasthan, India Vandana Singh Department of Microbiology, School of Allied Health Sciences, Sharda University, Gr. Noida, Uttar Pradesh, India Mamta Tandon MATS School of Sciences, MATS University, Pagaria Complex, Raipur, Chhattisgarh, India Sreedevi Upadhyayula Heterogeneous Catalysis and Reaction Engineering Laboratory, Department of Chemical Engineering, Indian Institute of Technology Delhi, New Delhi, India Sanjeev Verma Department of Chemical Engineering & Technology, IIT(BHU) Varanasi, Varanasi, Uttar Pradesh, India Shivani Verma Department of Chemistry, G. B. Pant University, Pantnagar, Uttarakhand, India Lata Vodwal Department of Chemistry, Maitreyi College, New Delhi, India Anoop Yadav Department of Environmental Studies, Central University of Haryana, Mahendergarh, Haryana, India Nitin Yadav IISER, Kerala, India

Thiruvananthapuram,

Sushma Yadav Industrial Waste Management, Department of Vocational Studies and Skill Development, Central University of Haryana, Mahendergarh, Haryana, India

C H A P T E R

1 Introduction to environmental and green chemistry Sushma Yadav1, Anoop Yadav2, Chandra Mohan3, Vinod Kumar Garg4 and Neeraj Kumari3 1

Industrial Waste Management, Department of Vocational Studies and Skill Development, Central University of Haryana, Mahendergarh, Haryana, India 2Department of Environmental Studies, Central University of Haryana, Mahendergarh, Haryana, India 3Department of Chemistry, School of Basic and Applied Sciences, K. R. Mangalam University, Gurugram, Haryana, India 4Department of Environmental Science and Technology, Central University of Punjab, Bathinda, Punjab, India

1.1 Introduction to environmental chemistry There is no precise definition of environmental chemistry. Different people have different mindsets and so there are different definitions of environmental chemistry. Environmental chemists play a crucial role to resolve various environmental issues like global warming, ozone layer depletion and many more. Similarly, environmental chemistry also plays a big role on regional as well as local scales. This brief analysis clearly indicates the link between environmental chemistry and human beings. Many people think that environmental chemistry is indirectly linked to pollution, but this is not true [1]. The beginning of the universe was due to the huge detonation, also called Big Bang. The evidence of this detonation was also found by astronomers in the background of microwave radiations and the movement of galaxies. After Big Bang, in the first segment, the amount of matter and radiation was fixed at a ratio of 1: 108. After some time, the amount of hydrogen, deuterium and helium was fixed. Heavy elements like iron can be found in the heart of stars, while much heavier elements are produced due to the explosive supernovae. The most abundant elements in the universe are hydrogen and helium. A low abundance of lithium, beryllium and boron is found in the universe as they are not stable in the centre of the solar system, while carbon, nitrogen and oxygen are found in excess as they are produced by cyclic process in stars [2,3].

Green Chemistry Approaches to Environmental Sustainability DOI: https://doi.org/10.1016/B978-0-443-18959-3.00005-7

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1. Introduction to environmental and green chemistry

1.1.1 Origin and evolution of earth The segments of stellar supernovas produced disc-shaped clouds of hot gases which further produced the planet of the solar system. The condensation of vapours results in the formation of solids which combined further and form small bodies. The accretion of these small bodies formed dense inner planets (Mercury to Mars). As the Earth accreted, it heated up due to trapping kinetic energy and the radioactive decay of unstable isotopes. The heating melted iron and nickel allowed the dense inner particles to sink at the center of the planet resulting in core formation.

1.1.2 Formation of the crust and atmosphere The crust and atmosphere are formed due to the release of materials from the upper mantle of the early earth. The crust of oceans is mainly convoyed by the release of water and gases. The rock shell having , 0.0001% volume of the whole planet is probably accounted for similar processes. The composition of rock shells changed over time and in the present crust, oxygen is present as the most abundant element. It can also form silicate minerals by combining with silicon, aluminium and other elements [4].

1.1.3 Origin of life and atmosphere We are not sure about the organic molecules’ synthesis, the self-replicating structure of organisms but at some point, we can guess. In 1950, when deoxyribonucleic acid (DNA) and some primitive biomolecules having methane and ammonia were discovered, a clear picture of the origin of life came into light. However, it is also estimated that the development of biological molecules takes place in specialized conditions like in submarine volcanic vents or clay mineral’s surface [5]. Some facts confirmed that life began 4.2
3.8 billion years ago in the oceans. Some fossils evidences showed advanced metabolisms where solar energy was utilized for the synthesis of organic materials. At an early stage, autotrophic reactions were dependent on sulphur which was obtained from volcanic vents.

CO2 g 1 H2 S g -CH2 OðsÞ 1 2SðsÞ 1 H2 OðlÞ Organic Matter However, the splitting of water through a photochemical process or photosynthesis process happened 3.5 billion years ago.
H2 OðlÞ 1 CO2 g -CH2 OðsÞ 1 O2 ðgÞ After photosynthesis, rapid consumption of oxygen gas took place as it oxidized various reduced compounds. Once the rate of consumption of oxygen exceeded, it started to produce in the atmosphere. Additionally, various photochemical reactions of oxygen in the stratosphere resulting in the production of ozone (O3) which prevents the earth from harmful ultraviolet radiations. Ozone acts as a shield for the organisms that resides on the land surface [6]. Therefore chemistry plays an important role in a human being’s life. Each matter present in the universe is created by the chemicals. The changes observed by us in our daily

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life are only possible due to the chemical reactions. As the time passed, significant developments in various fields done by the human being resulted in changing the environment due to which the life of human beings changed and it is all possible due to chemistry.

1.2 Environmental chemistry There are various definitions of environmental chemistry suggested by the environmental experts. It is the branch of chemistry that generally deals with origins, reactions, their impacts, various chemicals species present in air, water, soil and their impacts, effects of human activities and technology thereon. It is the scientific study of various chemical and biochemical processes that generally occur in the environment. We can also define the environmental chemistry as the characteristics of physical, organic, analytical and inorganic chemistry along with some other disciplines like public health, biology, biochemistry, epidemiology and many more [7].

1.2.1 Importance of environmental chemistry Environmental chemistry is considered important at a societal level as it is linked with pollutants and their impact on the environment, reduction of contaminants and environmental management. The living beings including human beings found on the Earth are exposed to the chemicals and used these chemicals as nutrients. The contaminants present in the environment are due to forest fires, floods, volcanoes, etc. Human beings are also responsible for the contamination of the environment to some extent. To understand the effect of these chemicals on the environment, it is required to examine behaviour of chemicals in the precise and entire environment. The environmental chemistry is generally classified into five components to challenge natural system diversity as shown in Fig. 1.1 [4]. Aquatic chemistry generally describes about the distribution and circulation of water and chemical species present in waterbodies like lakes, oceans, rivers or underground FIGURE 1.1 Components of environmental chemistry.

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1. Introduction to environmental and green chemistry

water. Soil chemistry deals with the study of soil and its physical and chemical characteristics. Atmospheric chemistry discusses about the species which describe various physical and chemical characteristics of their surrounding atmosphere. Toxicological chemistry is the branch of chemistry that describes toxic substances and their interaction with living beings. Green chemistry generally discusses about the synthesis process of chemical compounds and their applications, which are also used for the elimination of hazardous substances [8]. All the above components are considered as the characteristics of the physical environment, enclosed in a boundary that separates them from the rest of the world. The chemical behaviour in the environment is mainly explained by the characteristics of environmental components and physicochemical characteristics of chemicals. Various factors can be considered in the environmental chemistry that affects interaction, distribution, the way of transportation, and transfer of elements, gases and substances present in the environment. Therefore “environment” can be defined as any physical or chemical support to hold various foreign particles by involving the natural compositions for the support. Thus the essential components like air, water and soil for the troposphere, hydrosphere and lithosphere can also be considered as three natural environments along with natural composition. The chemical substance plays a major role to control and regulate animal and plant behaviour in the ecosystem, and currently, this is a major research area. In fact, it comprises chemical ecology also, a branch of ecology. The interaction of living beings with the environment can also be explained based on the secretion of various substances, also called “allelochemicals” that affect the behaviour and growth of other organisms. One important interpretation is that environment is contaminated by each biosphere unit and the biosphere unit also contaminates the environment. Therefore, each unit should have control over emissions and immission.

1.2.2 Contamination and pollution Contamination and pollution are the terms used synonymously. Contamination is the release of substances in the environment at measurable concentrations, while pollution is the presence of substances in the environment affecting the living organisms. For example, the release of oxygen during the photosynthesis process is an example of an environmental contaminant, while the rose scent is an environmental pollutant example. The dispersion of various chemicals in measurable concentration in the environment is contamination, and if the concentration of these chemicals increased to a level that have an undesirable effect is the pollution. Thus, contamination can be pollution, but pollution is not contamination. Except for radioactivity and noise contamination, all environmental contaminations can be classified based on the chemical nature. Most of the environmental problems are due to the following reasons: 1. The pollution related to oil and oil waste. 2. Biological oxygen demand due to organic waste dispersion. 3. Eutrophication of inland water.

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4. Some specific toxic chemicals like pesticides are responsible for environmental contamination. 5. Dispersion of individual elements like metal in the environment. There are mainly two types of contaminants based on their origin: natural (due to nature) and anthropogenic (due to human activities) contaminants. Natural and anthropogenic contaminants are further classified into inorganic (metals like heavy metals and anions like halide, sulphate, nitrate etc.) and organic contaminants (hydrocarbon, pesticides, organometals etc.).

1.3 Introduction to green chemistry Green chemistry, sometimes also called sustainable chemistry, is the branch of chemistry that discusses the design of chemical products and optimization of chemical processes to reduce the toxic substances production and their uses. Green chemistry is different from the environmental chemistry. Currently, green chemistry plays an important role in the prevention of pollution due to its innovative scientific ideas. Chemical industries caused different types of pollution like soil, water and air pollution; therefore, various efforts have been attempted to develop a manufacturing method so that this pollution could be reduced without any negative impact on the environment. Therefore, the main concern to design green chemistry was to reduce pollution. The idea came to light in 1990. Paul Anastas, known as the Father of Green Chemistry, and John C. Warner published a book, Green Chemistry: Theory and Practice in 1998. They mentioned 12 principles of green chemistry in order to reduce the environmental pollution risks and minimize the carbon footprints [9,10]. Various terms have been introduced in the concept of “green chemistry” like ecoefficiency, sustainable chemistry, atom economy, inherent safety, ionic liquids, renewable energy resources and many others. Green chemistry is different from cleaning up pollution as it reduces pollution by minimizing or removing the hazardous waste of chemical feedstock, solvents, reagents and products [11]. Cleaning up pollution is also known as remediation involving waste treatment by separating the chemical hazard, and then treatment is done for making them less hazardous. Remediation is completely different from green chemistry. During remediation, hazardous substances are removed from the environment while in case of green chemistry, hazardous materials always remain out of the environment [12]. If the reduction or elimination of toxic chemicals is done by a technology to keep the environment safe, then this technology can be termed as green chemistry. For example, if a toxic chemical is used to remove the mercury from waterbodies, then there is no use of that toxic chemical as the synthesized toxic adsorbent becomes more toxic after adsorption of mercury [13,14]. On the other hand, in case of green chemistry, mercury is removed from waterbodies using nonhazardous chemical adsorbent so we can say that remediation technology satisfies the green chemistry definition.

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1. Introduction to environmental and green chemistry

1.4 History and origin of green chemistry The production of hazardous chemicals and their threats to the environment and human beings were the challenges for the chemical society and they were trying for an environment friendly solutions. The concept of green chemistry was given in 1990; many studies have been done for the establishment of this new concept which was the beginning of green chemistry. However, “green chemistry” term was not in the literature and books 20 years ago. The main issue was to find the best ways for the reduction of environmental pollution which represent a remarkable difference between green and environmental chemistry [15]. In 1991 various programmes and policies related to green chemistry were introduced by the United States, Italy, United Kingdom by Japan. Experts related to this field gave a complete definition of green chemistry. “The branch of chemistry used to investigate and design compounds and methods used for their synthesis to prevent the utilization and production of toxic and hazardous substances.” The efforts by chemical society to suggest various chemical ways for waste treatment and mitigate the impact of pollutants on the environment have not always been a feasible solution. In 1980 and 1990, several terms were suggested related to this field like environmental chemistry, clean chemistry, benign chemistry, sustainable chemistry and green chemistry. All the terms were broadly discussed among experts, and green chemistry becomes the most popular among various alternatives (Fig. 1.2) [16,17]. By 1990, green chemistry was a global term and about 175 countries approved the term in 1992 related to controlling and disposal of hazardous waste in agreement with policies

FIGURE 1.2 Idioms “green chemistry” in research published from 1990 to 2010.

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1.4 History and origin of green chemistry

also. They also encouraged different industries, researchers and academia to design green materials to prevent and reduce hazardous wastes [18]. This kind of progressive step urged all the researchers to work in this field and published several texts between 1994 and 1999. The objective of green chemistry is the development or fabrication of chemicals and their application which reduce the use of hazardous substances and are not concentrated in the environment (Fig. 1.3) [19].

1.4.1 Synthetic chemistry and green chemistry Synthetic chemistry is the branch of chemical science in which we study preparation of new chemicals and develop amended ways to synthesize the existing chemicals, whereas green chemistry generally describes the designing of chemicals/products with environmental prospects. Synthetic chemistry has come late to the exercise of environmental chemistry. From the beginning, analytical chemistry played a crucial role to monitor the problems generated due to pollution, whereas physical chemistry always helped to explain the environmental problem through the chemical modeling. Other branches of chemistry have also been involved to study various chemical phenomena related to the environment. Now is the time for synthetic chemists to synthesize environmentally friendly chemical products through different synthesis methods to use them for different purposes and finally dispose them. Instead of environmental and health issues of chemicals, economic aspects of chemical production and their distribution is also a main factor. The economic costs involved feedstock cost, energy requirement, marketability, regulatory conformity, liability, waste treatment and waste disposal. Therefore by eliminating or reducing toxic substances including feedstocks and catalysts use and production of intermediate and by-products, green FIGURE 1.3

Concept of green chemistry.

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chemistry also reduce the extra cost that is associated with environmental and health requirements. Generally, there are two complementary approaches used to implement green chemistry for chemical synthesis as shown in Fig. 1.4. First is to use existing feedstocks by making them more environmentally friendly and the second is the substitution of other feedstocks which are prepared for the purpose of environmentally friendly means. In many cases, both approaches are used [20].

1.4.2 Need of the green chemistry Within the limitation of the broad context of chemistry, it is necessary to relate the consequences of chemicals and their related products with the chemistry of the surrounding atmosphere. However, environmental chemistry is a science that investigates, appreciates and expects all the safety measures [16]. Therefore scientific and technological data used to determine, interpret and predict the problems related to the environment help us to minimize the concentration of toxic chemicals. Green chemistry mainly deals with the manufacturing of chemicals, and clean technologies must be focused on the conversion of chemical reactions [21]. The correlation of chemicals with their pollutant nature allows the chemists to control on the toxicity of chemicals and that harness green chemistry to serve as organic chemistry. The degradation of the environment is due to chemicals and hence it is necessary to understand the mechanism of the degradation of chemicals along with their design and also their consequences if released into the environment [22]. The purpose of green chemistry is not only to synthesize non-toxic chemicals but also to reduce the introduction of any harmful chemicals into the environment. Green chemistry also diminishes the chemical processes through which millions of tons of harmful waste generated which need treatment or recycling. There are many chemical and petrochemical industries that usually spends about $ 1 billion annually on research and development for the purpose of disposal of toxic chemicals, and hence provide importance to green chemistry to address the pollution problems [23]. Therefore instead of handling and controlling pollution, there is a need to focus to stop the formation of harmful products from the grounds. This will help developing countries to improve their economic performances and support their various projects related to their development. Through the convergence between this development and green chemistry, sustainable development can be

FIGURE 1.4 Two general approaches used for the implementation of green chemistry.

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1.4 History and origin of green chemistry

9

achieved with economic and environmental wealth. Sustainable development can also be achieved by focusing on the sources related to renewable resources to acquire raw materials and this strengthens biotechnology. This kind of support can be beneficial for various technologies used to produce energy like biofuel production [24]. Natural science always geared to face new challenges as they offer some basic knowledge required to support new technology which further supports sustainable development. This concern directly point toward chemistry that describes the need for green chemistrys. There is a discriminatory role of chemistry in science. Industrial chemistry developed throughout the 20th century was mainly responsible for the environmental disasters due to the production of harmful chemicals and their deposition in the surroundings. Therefore it is important to check all the products used during the manufacturing. There are different types of materials used for different purposes like cosmetics, plastic materials, household cleaners, building materials, chemicals used in agriculture and medicines, which require proper investigation before and after manufacturing. Therefore this is necessary to introduce such type of technology that aims to explore innovations to keep balance in the environment, improve the quality of life and reduce environmental problems [25].

1.4.3 Basic principles of green chemistry The basic principles of green chemistry focus on the development of processes and the use of products in a sustainable way. In 1998, Anastas and Warner discussed the major principles of green chemistry in their seminal book [9]. However, some new principles have also been added to the list (Fig. 1.5) [26]. These principles describe about the design of new chemical products with low toxicity using renewable raw materials in minimum time with high yield and without producing waste products. These principles promote green innovations in industrial applications, particularly for the production of agrochemicals with full control of the emission of pollutants in the surroundings. They professed that the processes used during the production of the chemicals which have a negative impact on the environment should be replaced by less polluting chemical processes [27
29]. 1.4.3.1 Prevent waste This principle simply provides a statement that chemical processes used for the synthesis of chemical products should be such that the minimum amount of waste is produced. It is better to prevent the waste formation rather than to treat it after generation. The waste can be in any form and affect the environment in different ways depending on its quantity, nature, toxicity and the mode it spread in the environment [30]. In 1992, a concept in the form of environmental factor was accepted which was introduced by Roger Sheldon. This is also known as the environmental impact factor. This factor is mainly used to determine the amount of waste generated per kilogram of the product. This factor mainly helps to consider the “environmental acceptability” of a chemical product and its process. E factor is calculated by using the following formula [31]: E factor 5

Total mass of waste produced during the process Total mass of the product

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FIGURE 1.5 Twelve principles of green chemistry.

Ideally E factor should be zero, higher the value of E factor, less desirable will be the product. E factor can be accepted depending on the product value and volume of product produced. In industries where million tons of different chemicals are produced per year, E factor can vary from 1 to 5 [31]. As shown in Fig. 1.6, there are two possible approaches for the synthesis of ethylene oxide: one is a traditional method where ethylene oxide is prepared through chlorohydrin intermediate and the other one is a modern approach where ethylene oxide undergoes oxidation. The E factor calculated for the entire process is 5, it means 5 kg is waste that will be disposed on the production of 1 kg of product which is not acceptable from the environmental safety point. In the new route for the synthesis of ethylene oxide where molecular oxygen is used instead of chlorine, the E factor received from this process is 0.3 kg, which is 16 times lesser than the original process.

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1.4 History and origin of green chemistry

FIGURE 1.6 Synthesis of ethylene oxide through traditional and modern approaches.

Traditional approach:

Modern approach:

By-products cannot be ignored during the synthesis process, some innovative solution should be applied where waste can be used as raw material for some other significant processes. This approach is mainly applied during the production of biofuels [32
34]. 1.4.3.2 Atom economy This term is also known as atom efficiency and introduced by Barry Trost in 1990. This concept is mainly based on maximum utilization of raw materials so that maximum number of atoms are consumed from a reactant and could be present in the products [35]. There should be incorporation of all atoms of a reactant for an ideal reaction. Atom economy is measured as follows [36]: Atom economy 5 %Atom economy 5

molecular weight of the product molecular weight of the all the reactants involved in the reaction

molecular weight of the product 3 100 molecular weight of the all the reactants involved in the reaction

The value of atom economy generally helps to determine the efficiency of a reaction. To explain the concept of atom economy, examples of the Grignard reaction and Diels
Alder reactions are shown in the figure. In the case of the Grignard reaction, the value of atom economy is 44.2% indicating loss of more than half of the raw material, while in the case of Diels
Alder reaction, the atom economy value is 100% where all the atoms present in the reactant consumed for the formation of the final product (Fig. 1.7) [37,38]. Therefore atom economy is better in various ways as it measures the efficiency of a reaction rather than yield. The processes in which atom economy is maximum should be preferred. 1.4.3.3 Less hazardous chemical synthesis The basic principle of green chemistry is to minimize the toxic and hazardous chemicals in all fields of chemistry without the need for environmental protection. To reduce the chemical risks, two approaches can be followed: reduce the concentration of toxic chemicals or reduce their exposure time. Reduction of chemical exposures may take several forms like the use of masks, protective clothes or techniques used to control the explosive

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1. Introduction to environmental and green chemistry

FIGURE 1.7 Grignard reaction and Diels
Alder reactions showing atom economy.

reactions. Practically, the hazardous chemicals can be assessed based on two factors: first, as it is not possible to avoid exposure to chemicals, therefore, it is required to increase the cost of clothing, masks and technologies. The second factor is the moral factor as it is the responsibility of chemists to innovate environmentally friendly materials that are safe for human beings also. There is no use of green chemistry if hazardous substances could not be avoided [39]. One of the most examples is the preparation of polycarbonate where phosgene is substituted by the least toxic substituent and is not dangerous to the environment. In the traditional method, phosgene is used as initial materials with bisphenol-A and NaOH through condensation polymerization and water and methylene chloride is used as solvent. In the reaction, phosgene is known for its high toxicity and methylene chloride is a cancercausing solvent. Methylene chloride is used on a large scale about 10 times more than the amount of polymer produced. The recovery of methylene chloride is also not possible due to its low boiling point and high solubility in water (Fig. 1.8) [40]. In the modern approach, the use of phosgene and methylene chloride can be avoided. The modern method is known as the melting process and environmentally friendly as it does not use phosgene and methylene chloride so it can be considered that this method fulfils the standard of pollution prevention. 1.4.3.4 Designing safer chemicals This principle can be linked with the previous one. Chemists should ensure that the product synthesized by them should have minimal toxicity and fulfill all the prevention standards in medical, industrial and other fields. Chemists should also have the knowledge of interaction of safer chemicals in the human body and the environment. In some cases, the toxicity level of chemicals in humans or animals can be avoided but their alternatives should be known. The main target to design safe chemicals is to make a balance of the highest functional efficacy with minimum toxicity potential. Fortunately, these targets can be achieved by chemists easily as they follow a close relationship between the molecular structure and chemical properties of the chemicals. There are many reactions like cycloaddition, rearrangement and many other reactions that fall under the category of efficient reaction. The necessity to prepare safer chemicals is due to the advanced research indicating the poisoning nature of chemicals also. The efficacy of a chemical can be investigated

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1.4 History and origin of green chemistry

OH

OH

FIGURE 1.8 Traditional and modern approaches for the synthesis of polycarbonate. Green Chemistry Approaches to Environmental Sustainability

13

14

1. Introduction to environmental and green chemistry

by the extent to which it obtained the functionality for which it is designed. In the past, it was not easy to identify the toxicity level of the chemicals but in the present day, it is possible to understand the mechanism of interaction of chemicals with the human body and environment as the composition of chemicals can be modified to reduce the toxicity level. Therefore, it is observed that chemicals produced using modified chemical reactions are safer for the environment [41,42]. 1.4.3.5 Safer solvents and auxiliaries There are many concerns about the organic solvents like methylene chloride, chloroform and carbon tetrachloride which are used in chemical reactions to facilitate them. These solvents used many aromatic reactions but to a lesser extent as their detrimental effects due to their flammable, volatile and carcinogenic nature have been proven. Their detrimental effects are not limited to human beings but extend to the ecosystem also. Their excessive use especially chlorofluorocarbon is mainly responsible for the depletion of the ozone layer [43]. Volatile organic compounds used in various chemical applications cause smog smoke phenomenon in the ecosystem due to which respiratory problems occurred in human beings. Therefore, many companies received penalties and suggested using their alternatives [44]. Recrystallization is the most common method used to separate and purify chemical compounds where energy or other chemicals are used to modify the solubility of the materials. The other one is chromatography which consumes some auxiliaries but their quantity depends on the separating materials. When they are used in large amount, it is accompanied by other substances having harmful effects. Therefore, this is necessary to consider the waste and energy along with the effect of additives [45]. Therefore in the past few years, the advancement in organic reactions has happened and these organic solvents are replaced by safer green solvents ionic liquids, supercritical CO2 fluid, water or supercritical water and also solvent-free systems. 1.4.3.5.1 Ionic liquids

Ionic liquids have non-volatile nature and no vapour pressure. These solvents are liquid at room temperature and below. No special apparatus or methodologies are required for the reactions occurred in the presence of ionic liquids. They are best substituent for volatile organic solvents as these solvents can be recycled [46]. 1.4.3.5.2 Supercritical CO2

Another green solvent is supercritical liquid in the form of fluid having low viscosity and no surface tension. The specialty of these solvents is that they can diffuse from any system and can dissolve various organic solvents. This liquid ishighly stable, less toxic, non-flammable and can be used at low temperatures. Supercritical CO2 is an important solvent for various commercial and industrial applications As CO2 is evolved as byproducts in various chemical and industrial processes, it is inexpensive and being a gas, it easily evaporated without leaving any residue [47].

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15

1.4.3.5.3 Supercritical water

Most of the organic substances are not soluble in water but the solubility can be enhanced when it becomes supercritical at 374  C and 218 atm. Hence, this clean and cheap solvent is used as a green solvent for many synthetic reactions. 1.4.3.5.4 Reactions in aqueous phase

The application of water as a solvent for various organic reactions was still unknown till the middle of the 20th century. However, when organic solvents were replaced with ecofriendly water, it was a great success as many organic reactions like oxidation, epoxidation, polymerization and many other reactions also take place in water at higher rates because of its high polarity (Fig. 1.9) [46]. 1.4.3.6 Design for energy efficiency A certain amount of energy is required for many chemical reactions either to dissolve the compound in a solvent or to enhance the rate of reaction. Most of the time, thermal energy is used for completion of the reaction beyond the activation energy. This is only possible if catalysts are used in the chemical reactions as they not only reduce the activation energy but also the energy required to complete the reaction. As some of the reactions are exothermic in nature due to which a large amount of energy is released; therefore, it is necessary that the reactions must be controlled by intensive cooling in a fraction of seconds. Another process like purification and separation consumes a lot of energy during the separation of impurities from the products as these processes are carried out through recrystallization or distillation. Therefore, this is necessary to design such kind of reaction where less energy is used during purification and separation. There are many reactions

FIGURE 1.9 Organic reaction in aqueous media.

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1. Introduction to environmental and green chemistry

like cycloaddition/ or pericyclic performed using ultrasonic energy. Friedel
Craft reactions are carried out in the presence of photovoltaic energy [48,49]. 1.4.3.7 Use of renewable feedstocks The source to obtain renewable materials are petrochemical products derived from the fossil fuels and agriculture products. Currently, this is a challenge for the scientist and researchers to use renewable materials in chemical reactions as it is well known about the negative effect of fossil fuels on human health and the environment. The petroleum and petrochemical products have indirect effects on human health and the environment which thrived in the last of the 20th century [50]. 1.4.3.8 Reduce derivatives Derivatives mean blocking, inhibiting or protecting groups used in various physical and chemical reactions. These derivatives are mainly used in organic reactions like for the preparation of drugs, dyes or pesticides as it is easy to formulate such types of chemicals which readily mix with others. These derivatives prevent a certain part of the molecule to alter by allowing transformation at another part. However, during the reaction, the extra reagent required results in the generation of waste. Therefore during the chemical reactions, use of blocking/ protecting groups should be avoided. From the past few years, an alternative that has been explored is the use of enzymes. Enzymes target on a particular part of a molecule without using protecting group or other derivatives [51]. 1.4.3.9 Catalysis Catalysts never take part in any chemical reaction, but they enhance the rate of the reaction. They can be recycled several times and do not generate any waste resulting in higher atom economy. There is no doubt about the efforts done while selecting a right catalyst with specific selectivity. They are most commonly used as stoichiometric reagents. The selectivity of catalyst also plays an important role in green chemistry as it stimulates the reactant to carry out the reaction by preventing or minimizing the waste production. Catalysts play a significant role in the conversion of the industrial waste into useful compounds. More than 70% of industrial products are prepared using the catalysts [52]. They are also used to improve the air quality by reducing the use of volatile organic compounds. Some alternatives have also been developed where chlorine or chlorine-based intermediate has been replaced with minimum waste during chemical synthesis. For example, in the conventional approach of synthesizing acetaldehyde from ethane, PdCl2/CuCl2 catalyst has been used that resulting in the generation of chloride ions in excess that have health or environmental concerns, while PdCl2 and V-complex catalyst are used as alternative in the modern approach where there is a drastic reduction in the concentration of chloride ions (Fig. 1.10) [53,54]. A catalyst can also be used to carry out various chemical reactions:

FIGURE 1.10

Synthesis of acetaldehyde in the presence of catalyst.

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1.4.3.9.1 Acid catalyst

Solid acid catalysts like fluoride silica-alumina catalysts can be used as an alternative to hydrogen fluoride, which is a highly corrosive and hazardous chemical. 1.4.3.9.2 Polymer supported catalyst

A polymer super acid catalyst synthesized through the interaction of aluminium chloride to sulfonated polystyrene is used for the cracking and isomerization of alkanes at 357  C at atmospheric pressure. 1.4.3.9.3 Photocatalysts

Titanium-oxide-based photocatalytic systems have been used to purify the polluted water, CFC decomposition and the disintegration of offensive odours and toxins. 1.4.3.9.4 Phase transfer catalysts

Phase transfer catalysts (PTCs) are the catalysts that facilitate the transfer of reactants from one phase to another phase. This is a method of accelerating the reaction between water-soluble and insoluble reagents/organic compounds. For example, some ionic reactants are often soluble in aqueous media, while insoluble in organic solvents in the absence of PTC. Therefore, PTCs can be used to accelerate the reaction, achieve higher yields, make fewer by-products and eliminate the need for hazardous solvents and expensive raw materials or minimize waste. 1.4.3.9.5 Biocatalysts

In case of green chemistry, biocatalysts play an important role and can be used in form of enzymes. The transformation of reactant to product in the presence of enzymes is known as biocatalytic conversion (Fig. 1.11). There are various advantages of the biocatalytic conversions: 1. 2. 3. 4. 5.

Most of the reactions are performed in aqueous medium Performed at ambient temperature and pressure. The biocatalytic conversions normally involve only one step. Protection and deprotection of functional groups is not necessary. The conversions are stereo specific.

1.4.3.10 Design for degradation The main concern related to chemical products is that they are present in the environment for a long with any degradation and enter into body of a living being, and FIGURE 1.11 Transformation of sugar and glucose into products in the presence of enzymes.

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1. Introduction to environmental and green chemistry

accumulate in their tissues that directly or indirectly affect their health, for example, plastics. Although plastics had many important applications throughout history, they stabilized after disposal and remain in the environment for several years. Some organic compounds like dichlorodiphenyltrichloroethane (DDT), one of the insecticides, are organic halogen compounds that damage the plant and animal tissues after accumulation. Therefore the chemical products should be designed in such a way that they break down easily into less toxic products without harming the environment. While designing the chemical products, their physical and chemical properties should be taken into account along with their decomposition products [55,56]. 1.4.3.11 Real-time analysis for pollution prevention This analysis technique is used to monitor the preparation steps of a chemical reaction to prevent the formation of hazardous chemicals before the completion of the reaction [57]. Through real-time monitoring, the reaction can be stopped by spotting the warning signs before the occurrence of any accident. Analytical chemistry plays a crucial role in green chemistry as sometimes it is not possible to control the reaction; therefore, by developing reliable sensors and analytical techniques, the risk can be assessed in the chemical reaction. The formation of toxic by-products or side reactions can also be controlled using these advanced features [58,59]. 1.4.3.12 Inherently safer chemistry for accident prevention There is always a risk of accidents while working with chemicals. However, risk can be avoided by managing the hazards. This principle directly or indirectly linked with other principles that describe about the toxic reagent or products or solvents. The accident prevention starts with the identification and assessment of the risks. For example, during the preparation of gold nanoparticles, diborane (highly toxic and explodes into flame near room temperature) and cancer-causing benzene were generally used, which are now replaced by NaBH4 that is environmentally friendly [60].

1.4.4 Future challenges The accomplishment in green chemistry is remarkable due to the continuous efforts of scientists, researchers and academicians all over the world. However, these achievements were obtained after facing the grand challenges and some challenges are still to be addressed. A few unavoidable challenges are as follows: 1.4.4.1 Twelve principles as consistent approach The framework of 12 principles of green chemistry can be used as a prototype to carry out advancement in the research. However, these 12 principles are not 12 independent purposes but an integrated consistent system. Sustainable development is only possible by applying all the principles. To find out reinforcing attributes, sustainable design is possible in a systematic way by facilitating transformative inventions.

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1.4.4.2 Multifunctional catalysts There is a significant advancement achieved is the application of catalysts. However, most of the catalysts have been designed to act in one chemical reaction only and very few are known about their multifunctionality. If multi-functional catalysts are designed for various independent reactions or complete synthesis takes place in one step, chemistry will touch a new level as the complex molecules having higher energy efficiency and high yield could be prepared. 1.4.4.3 Working on uncertain interaction/ forces of chemical products and their properties Non-covalent/weak interactions between the atoms in a molecule impart a major role in chemistry. Analyzing a compound’s properties through weak interactions and conducting a synthesis reaction in the same pattern while diminishing bond forming/bond breaking processes can lead to considerable improvements. Working on weak interactions shows a great potential to achieve the sustainability at molecular level. 1.4.4.4 Integrative system consideration The conventional approach to investigate in a scientific way is generally based on the depth of understanding and invention that created the modern life from communication to shipping to drugs. It has also caused a remarkable but unexpected concern that has damaged the environment and human life. Therefore green chemistry shows a tremendous invention while rejecting expected outcomes. By combining reductive and integrated ideas, transformative inventions can be carried out.

1.5 Conclusion Scientists have been trying to invent the molecules, materials and fabrication processes for societal and economic development. Green chemistry confirms that all the creatives be practiced in such a way that leaves a positive impact on human beings and the environment. Therefore the basic objective of green chemistry is to reduce the negative impacts of chemical products on human health and the environment by following the 12 principles of green chemistry. However, the remarkable invention has been done by scientists of green chemistry all over the world instead of many challenges. These principles can provide a roadmap for the scientists and researchers to eliminate toxic and hazardous types of chemicals and to design suitable methods to enhance economic, societal and environmental development.

References [1] G.I. Jorge, M. Hemandez-Esparza, C. Doria-Serrano, A. Fregoso-Infante, M.M. Singh, Environmental Chemistry Fundamentals, Springer, 2007. [2] Ronald A. Hites, Elements of Environmental Chemistry, Wiley Interscience John Wiley& Sons, Inc., Publication, 2007.

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[3] J. Sukla, P. Tiwari, Introduction to the Environmental Chemistry & It’s Importance in 21st Century in Research and Innovations in Chemical Sciences- An Approach towards Qualitative and Quantitative Studies and Applications. [4] Introduction to Environmental Chemistry in Comprehensive Analytical Chemistry, Elsevier, 32, 1999, 1
33, Available from: https://doi.org/10.1016/S0166-526X(99)80003-8. [5] Environmental Chemistry: A Historical Perspective, https://www.envchemgroup.com/environmental-chemistrya-historical-perspective.html. [6] J.E. Andrews, P. Brimblecombe, T.D. Jickells, P.S. Liss, B. Reid, An Introduction to Environmental Chemistry, second ed., Blackwell Publishing. [7] H.F. Hemond, E.J. Fechner, Chemical Fate and Transport in the Environment, Academic Press, San Diego, 1994. [8] S. Mitarlis, S. Ibnu, S. Rahayu, Environmental Literacy with Green Chemistry Oriented in 21st Century Learning. Development of Chemical Education in 21st Century Learning, AIP Conference, 2017. [9] P.T. Anastas, J.C. Warner, Green Chemistry: Theory and Practice, Oxford University Press, Oxford, 1998. [10] Introduction: green chemistry. Chem. Rev., 107 (6). 10.1021/cr0783784. [11] P.T. Anastas, E.S. Beach, Changing the course of chemistry, Hanging the Course of Chemistry, Green Chemistry Education, ACS Symposium Series American Chemical Society, Washington DC, 2009. [12] P.T. Anastas, J.B. Zimmerman, Mol. Basis Sustain. Chem. 1 (1) (2016) 10
12. [13] J.N. Armor, Striving for catalytically green processes in the twenty first century, Appl. Catal. A Gen. 189 (2) (1999) 153
162. [14] Basics of Green Chemistry. https://www.epa.gov/greenchemistry/basics-green-chemistry#:B:text 5 Green% 20chemistry%20is%20the%20design,%2C%20use%2C%20and%20ultimate%20disposal. [15] E.J. Woodhouse, S. Breyman, S. Green, Chemistry as social movement? Sci. Tech. Hum. Values 30 (2) (2005) 199
222. [16] R.A. Sheldon, Fundamentals of green chemistry: efficiency in reaction design, Chem. Soc. Rev. 41 (4) (2012) 1437
1451. [17] P. Anastas, N. Eghbali, Green chemistry: principles and practice, Chem. Soc. Rev. 39 (1) (2010) 301
312. Available from: https://doi.org/10.1039/B918763B. [18] M. Max, Advanced Green Chemistry-Part 1: Greener Organic Reactions and Processes, 3, World Scientific, 2017. [19] H. Lewis, J. Gertsakis, T. Grant, N. Morelli, A. Sweatman, Design 1 Environment: Global Guide to Designing Greener Goods, Routledge, London, 2017. [20] S.E. Manahan. Green chemistry and synthetic chemistry, 2021. https://chem.libretexts.org/Bookshelves/ Environmental_Chemistry/Green_Chemistry_and_the_Ten_Commandments_of_Sustainability_(Manahan)/ 02%3A_The_Key_Role_of_Chemistry_and_Making_Chemistry_Green/2.06%3A_Green_Chemistry_and_Synthetic_Chemistry. [21] S.E. Crawford, T. Hartung, H. Hollert, et al., Green toxicology: a strategy for sustainable chemical and material development, Env. Sci. Eur. 29 (1) (2017) 16. [22] A. Maertens, N. Anastas, P.J. Spencer, et al., Food for thought: green toxicology, Altern. Anim. Exp. ALTEX 31 (3) (2014) 243
249. [23] H.I. Abdel-Shafy, M.S.M. Mansour, Solid waste issue: sources, composition, disposal, recycling, and valorization, Egypt. J. Pet. 27 (4) (2018) 1275
1290. [24] K. Maxwell, P. Benneworth, The construction of new scientific norms for solving grand challenges, Palgrave Commun. 4 (1) (2018) 52. [25] M. Scheringer, Environmental chemistry and ecotoxicology: in greater demand than ever, Env. Sci. Eur. 29 (1) (2017) 3. [26] W. Leitner, P.G. Jessop, C.J. Li, Handbook of Green Chemistry E Green Solvents, Wiley-VCH, Weinhheim, 2010. [27] World Commission on Environment and Development, Our Common Future, Oxford University Press, Oxford, United Kingdom, 1987. [28] P.T. Anastas, T.C. Williamson, Green chemistry: an overview, ACS Symp. Ser. 626 (1996) 1
17. [29] S. Tang, R. Bourne, R. Smith, The 24 principles of green engineering and green chemistry: improvements productively, Green. Chem. 10 (2008) 268
269.

Green Chemistry Approaches to Environmental Sustainability

References

21

[30] E. Elbeshbishy, F. Okoye, Improper Disposal of Household Hazardous Waste: Landfill/ Municipal Wastewater Treatment Plant, Intech Open, 2019. [31] R.A. Sheldon, The E Factor: fifteen years on, Green. Chem. 9 (2007) 1273. [32] P. Marion, B. Bernela, A. Piccirilli, Sustainable chemistry: how to produce better and more from less? Green. Chem. 19 (2017) 4973
4989. [33] P. McClellan, Manufacture and uses of ethylene oxide and ethylene glycol, Ind. Eng. Chem. 42 (1950) 2402. [34] P.A. Kilty, W.M.H. Sachtler, The mechanism of the selective oxidation of ethylene-to-ethylene oxide, Catal. Rev. 10 (1974) 1. [35] B.M. Trost, The atom economy
a search for synthetic efficiency, Science 254 (1991) 1471. [36] M.J. Mulvihill, E.S. Beach, J.B. Zimmerman, et al., Green chemistry and green engineering: a framework for sustainable technology development, Annu. Rev. Env. Resour. 36 (2011) 271
293. [37] R.A. Sheldon, Atom efficiency and catalysis in organic synthesis, Pure Appl. Chem. 72 (7) (2000) 1233
1246. [38] M.B. Smith, J. March, in: March’s Advanced Organic Chemistry: Reactions Mechanisms and Structure, John Wiley & Sons Inc., New York, fifth ed., 2001, pp. 1205
1209. [39] G. Qu, S. Han, Z. Zhang, et al., Microwave assisted synthesis of 6-substituted aminopurine analogs in water, J. Braz. Chem. Soc. 17 (5) (2006) 915
922. [40] R.R. Poondra, N.J. Turner, Microwave-assisted sequential amide bond formation and intramolecular amidation: a rapid entry to functionalized oxindoles, Org. Lett. 7 (5) (2005) 863
866. [41] S.O. Hansson, L. Molander, C. Ruden, The substitution principle, Regul. Toxicol. Pharmacol. 59 (2011) 454
460. [42] V. Dichiarante, D. Ravelli, A. Albini, Green chemistry: state of the art through an analysis of the literature, Green. Chem. Lett. Rev. 3 (2010) 105
113. [43] C.J. Clarke, W.C. Tu, O. Levers, A. Brohl, J.P. Hallett, Green and sustainable solvents in chemical processes, Chem. Rev. 118 (2) (2018) 747
800. [44] G.P. Yang, X. Wu, B. Yu, C.W. Hu, Ionic liquid from vitamin B1 analogue and heteropolyacid: a recyclable heterogeneous catalyst for dehydrative coupling in organic carbonate, ACS Sustain. Chem. Eng. 7 (4) (2019) 3727
3732. [45] G. Giorgianni, S. Abate, G. Centi, S. Parathanor, S. Beuzekon, S. Soo-Tang, et al., Effect of the solvent in enhancing the selectivity to furan derivatives in the catalytic hydrogenation of furfural, ACS Sustain. Chem. Eng. 6 (12) (2018) 16235
16247. [46] B. Cornils, W.A. Herrmann (Eds.), Aqueous Phase Organometallic Catalysis—Concepts and Applications, Wiley-VCH, Weinheim, Germany, 1998. [47] K.Y. Khaw, M.O. Parat, P.N. Shaw, J.R. Falconer, Solvent supercritical fluid technologies to extract bioactive compounds from natural sources: a review, Molecules 22 (7) (2017) 1186
1207. [48] M.A. Laughton, in: Renewable Energy Sources, Watt Committee report 22, Elsevier Applied Science, 1990. [49] W. Soetaert, E.J. Vandamme, in: Biofuels, Wiley Series in Renewable Resources, John Wiley & Sons, Inc., United Kingdom, 2008. [50] M. Graziani, P. Fornasiero, Renewable Resources and Renewable Energy, A Global Challenge, CRC Press Taylor & Francis Group LLC, Boca Raton, 2007. [51] E.A. Peterson, J.B. Manley, Green chemistry strategies for drug discovery, R. Soc. Chemi UK. RSC Drug. Disc Ser. 46 (2015) 19. [52] C.R. Mathison, D.J. Cole-Hamilton, in: Catalyst Separation Recovery and Recycling, Springer, Netherlands, 2006, ch. 6, p. 145. [53] P.T. Anastas, M.M. Kirchhoff, T.C. Williamson, Catalysis as a foundational pillar of green chemistry, Appl. Catal. A Gen. 221 (1
2) (2001) 3
13. Available from: https://doi.org/10.1016/S0926-860X(01)00793-1. [54] O. Theresa, O. Adaora, E. Moses, The role of catalysts in green synthesis of chemicals for sustainable future, J. Basic. Phys. Res. 2 (1) (2011) 86
92. June, 2011. [55] R. Jayaraj, P. Megha, P. Sreedev, Organochlorine pesticides, their toxic effects on living organisms and their fate in the environment, Interdiscip. Toxicol. 9 (3
4) (2016) 90
100. [56] M. Eriksen, M. Thiel, M. Prindiville, T. Kiessling, Microplastic: what are the solutions? in: M. Wagner, S. Lambert (Eds.), Freshwater Microplastics Part of the Handbook of Environmental Chemistry, Springer, 2017, pp. 273
298.

Green Chemistry Approaches to Environmental Sustainability

22

1. Introduction to environmental and green chemistry

[57] F.R.P. Rocha, J.A. No´brega, O.F. Filho, Flow analysis strategies to greener analytical chemistry, An. overview. Green. Chem. 3 (2001) 216. [58] L.H. Keith, L.U. Gron, J.L. Young, Green analytical methodologies, Chem. Rev. 107 (2007) 2695. [59] A. Ivankovic, A. Dronjic, A.M. Bevanda, et al., Review of 12 principles of green chemistry in practice, Int. J. Sustain. Green. Energy 6 (3) (2017) 39
48. [60] T.J. Collins, Review of the twenty-three-year evolution of the first university course in green chemistry: teaching future leaders how to create sustainable societies, J. Clean. Prod. 140 (2017) 93
110.

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2 Environmental pollution Nidhi Gaur1, Swati Sharma2 and Nitin Yadav3 1

D.A.V Public School, Gurugram, Haryana, India 2Department of Physics, University of Rajasthan, Jaipur, Rajasthan, India 3IISER, Thiruvananthapuram, Kerala, India

2.1 Introduction Environment is the surroundings of any physical system that can interact with other such systems through the transfer of mass and energy. It comprises both the living and nonliving components but is the most intelligent species on earth; it is our sole responsibility to keep our environment clean and green. However, despite achieving unprecedented growth in all aspects of material development, even after being an age-old problem, environmental pollution continues to be a major global challenge and one of the prominent causes of oppression and mortality. Any unwanted substance in solid, liquid or gaseous form that causes an undesirable change in the surroundings is called a pollutant. Such change arises due to the increased concentration of that component due to natural causes or human activities, namely urbanization, industrial advancement and scientific exploration, to achieve better living standards and increased economic growth. These pollutants are transported to different places through the action of wind or water, impacting the landscape. Depending upon the origin, it may be a “point source” arising from a single identifiable source like power plants, wastewater discharge pipes and a “nonpoint source” originating from several sources spanning a larger area like agricultural runoff produced from thousands of acres of farmland (Figs. 2.1 and 2.2). In addition to the above-said classification, pollutants may be degradable (broken into simpler forms) easily (like vegetables) or slowly take decades to degrade (like heavy metals, pesticides) and nonbiodegradable (nuclear waste). The unwanted disposal of any of the earth’s natural resources (air, water and soil) negatively impacts the biotic and abiotic forms [1]. The normal optimum environmental processes (Kemp, 1998) are adversely affected by contaminants and pollutants, leading to primary damage, which may be quantified with proper impact monitoring, and secondary damage, which is noticeable over a prolonged time [2]. Environment is intimately related to all humans and other life forms through the food, intake of air and water, and as a

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FIGURE 2.1 Graphical representation of point sources and environment.

Industrial Waste/ Factories

how

they

are

transported

to

the

Municipal Sewage Waste

Storm Pipe

Point Sources Combined Sewer Outflow

Vessels

Water Treatment Plant

FIGURE 2.2 Graphical representation of nonpoint sources and environment.

Urbanic Runoff

how

they

are

transported

to

the

Mining/ Dredging

Forests and Farms Nonpoint Sources

Chemical Fertilizers

Agriculture

Constructi on Sites

consequence, life on earth is exposed to a plethora of hazardous chemicals and materials due to deteriorating environmental conditions. The survival of life on earth due to environmental degradation and contaminated natural resources has become the biggest challenge of the future as it directly impacts livelihood across the world. WHO estimates that

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23% of fatalities worldwide in 2012 were due to environmental reasons, with low- and middle-income countries accounting for most of this. Poisonous gas emissions from industrialization and chemical discharge leading to contaminated water bodies are taking 100 million lives annually. Polluted surroundings have also led to increased health risks because of the increased carcinogenic compounds in water, soil and air. A significant rise of 3.3 mm in sea levels yearly due to global warming is depleting the world’s glacier reserves. Besides affecting the quality of natural resources, pollution badly impacts the poor and the vulnerable, including women and children. It is a significant impediment to health, well-being, prosperity and the sustainable development goal of “leaving no one behind”. With the rapid rise in population, the exposure of masses to pollutants will increase unless certain policies to curb pollution are implemented with proper actions. It is the responsibility of both developed and developing nations to aware the people and regulate strict laws to protect their environment. Despite the rising pollution awareness, the impact is still being felt due to its long-term consequences. This chapter discusses the types of pollution, the causes (urbanization, industrial development, etc.) and the effects of pollution. It proposes strategies and solutions that emphasize the need for sustainable approaches to combating this environmental restoration problem. In addition, it also touches on the future scope of novel industrial and agricultural developments as future perspectives of environmental sustainability.

2.2 Types of pollution and its causes Earth is the only planet that supports all forms of life with the aid of abundant resources and elements which delicately fuse to form life-supporting compounds. Without water from the hydrosphere, oxygen from the atmosphere and nutrient-rich soil, it would not be possible for biotic and abiotic forms to survive on earth. Despite extensive research on ecosystems, the harmony of various life cycles and the feasibility of life on Earth, humans have been causing environmental damage through activities like progressive urbanization, industrialization, burning of fossil fuels, excessive plastic usage and other mining methods that result in various forms of pollution (Fig. 2.3). In addition, natural disasters also contribute to polluting significant life components, namely air, water and soil.

2.2.1 Air pollution The addition of any foreign substance in solid (particulates), liquid (droplets) or gaseous form (e.g., greenhouse gases) reduces the quality of air in terms of smell, oxygen content and health and makes it hazardous for other life forms termed as air pollution. The harmful gases and aerosols are released by natural processes (like a volcanic eruption or forest fire) and human activities through burning fuels like natural gas and coal. As a result, pollution has reached a level that is considered unsafe for human health and ecosystems. Depending on the type of source, the sources of pollution may be natural, induced by humans and even produced by humans.

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FIGURE 2.3 Pollution and its major types.

Radioactive waste Light Pollution Soil Pollution

Types of pollution

Water pollution

Plastic Pollution

Air Pollution

Noise pollution

The natural pollution sources majorly comprise volcanic eruptions and spontaneous forest fires producing smoke, ash, carbon dioxide, sulphur dioxide, other particulate matter and carbon monoxide. Plants are the sources of hydrocarbons, pollen dust, other organic compounds, methane and other sulphide gases after decay. Earth’s crust is witnessing human and animal decay, producing methane gas and radioactive decay-producing poisonous gases. Seas and oceans add solid and liquid particulate matter from sea salts. Lightening also converts atmospheric nitrogen into different oxide forms, which are not so healthy. Human-induced sources include the burning of forests by humans for plantation and water disposal landfills giving rise to poisonous gases like methane, carbon dioxide, ammonia, mercaptans and sulphides. The third type incorporates those pollutants which came up only after human existence. Primarily the list includes chlorofluorocarbons (CFCs) produced by industrial applications, increased use of pesticides and weedicides for enhanced production in the agriculture sector, nuclear and radioactive waste from nuclear power plants, and other carcinogenic metals like cadmium and lead compounds from the industrial boilers, refineries, smelters, etc.

2.2.2 Effects of air pollution Pollutants in the air impact humans by degrading their health conditions. They also corrode and damage cultural resources, deplete the ecosystem of natural resources and make the environment unhealthy for existence. The presence of particulate matter like dust, dirt and soot and reduced oxygen levels in the air leads to unhealthy air, thereby aggravating respiratory diseases in children and the elderly and increasing accidents due to reduced

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visibility. This issue worsens in cities due to urbanization, jam-packed roads because of large populations, industrial areas and other poor environmental conditions. Ramsey (2016) confirmed that urban air pollution increased by 8% globally from 2008 to 2013 [3]. A report released by WHO [4] on 12 May 2016 analyzed that about 80% of people living in urban areas showed that their air quality index is higher than the permissible limit [4]. Due to air pollution, there are episodes of problems like respiratory tract irritation. Exposure to CO reduces the oxygen-carrying capacity of the blood, and particulate matter is primarily responsible for severe lung ailments, including lung cancer. Exposure to sulphur dioxides and oxides of nitrogen leads to pulmonary irritation, and many severe issues indirectly linked to cardiovascular health. Besides human health, direct greenhouse gases like methane and carbon dioxide adversely impact the environment by trapping heat in the atmosphere. They react in the atmosphere to produce more hazardous substances, intensifying climate change. Global climate change and the destruction of the ozone layer are typically related to air pollution. Due to trapped heat in the atmosphere, the temperature at the earth’s surface is rising, resulting in the melting of glaciers and increased water levels in coastal areas. Many studies in this respect have been done to monitor temperature change at the global level [5]. Air pollutants like sulphur dioxide, fluorides, greater ozone levels and increased photochemical oxidants result in poor vegetation. Lastly, animals are also affected in the same way as humans, depending on their size and respiratory rate. Consuming forage contaminated with particulate pollutants may also lead to chronic poisoning in animals.

2.2.3 Possible solutions Air pollution not only brings economic losses, but costs human lives as well. The concerned management should formulate policies with comprehensive coverage of air pollution management and should consider other factors such as meteorology, available resources and topography. The formulation and the holistic implementation of such policies could only be achieved through joint efforts by both private and government sectors. Reducing air pollution is the need of the hour but limiting emissions and eliminating pollutants is difficult technically as rain is the only air-cleaning mechanism naturally available. Change at the product or the process level is more beneficial (like eliminating lead from gasoline curbed lead levels in urban air) than trapping the pollutant itself. At the global level, various policies have controlled air pollution and greenhouse warming, like The Montreal Protocol 1987, The Kyoto Protocol 1997 and the Clean Air Act in the United States. At the national level, different policies and laws are required to be framed to reduce air pollution, protect humans’ health, and preserve ecosystems and the environment. To get the desired result, various laws are formulated by developed nations to regulate emissions and thereby reduce air pollution. Some indirect laws and policies related to energy efficiency provide immense benefits in improving air quality and energy generation to control air pollution. Even at the local level, everyone can take steps to reduce air pollution by contributing individually, adopting certain lifestyle changes and obeying government laws in this respect. Encouraging the use of public transportation instead of individual private vehicles or sharing vehicles can help to reduce air pollution. Some local,

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state and national campaigns are very helpful in raising awareness of pollution and its deadly effects. With awareness, committing to controlling air pollution is another major tool to curb air pollution. People can also move toward green products to reduce the air pollution. Adopting sustainable development policies committed to achieving all SDGs is the need of the hour. Some of the cleanest cities in the world have switched to sustainable development policies; for example, Calgary (Canada), despite having a large oil and gas industry, is considered to be the world’s cleanest city [6]. Other clean cities include Honolulu (United States), which has a light manufacturing industry, Oslo (Norway) and the city of Stockholm (Sweden), with a famous transportation system to control traffic and air pollution from vehicles.

2.2.4 Water pollution Water is a prime resource for the survival of all kinds of life on our planet including plants, microorganisms and animals. The composition of natural water in rivers, lakes, ponds, springs and groundwater is affected by atmospheric conditions, temperature variations and natural processes like volcanic eruptions. Still, it is highly influenced by contaminated soil and human activities like industrialization and urbanization, posing a great threat to all the biotic forms on earth. It has eventually increased the levels of toxic elements in water; consequently, the whole ecosystem is severely affected. The contamination of water bodies by the inflow of chemicals without subsequent treatment for the removal of harmful compounds causes water pollution. There are standard parameters set by the Indian Standard Institute (ISI), World Health Organization (WHO) and National Interim Primary Drinking Water Standards (NIPDWS) to classify the water as polluted or not. Through different stages of the water cycle, the pollutants pass through different water bodies, and the mean lifetime related to a water molecule in a water body decides the potential of pollution. Moving systems like rivers witness a brief pollution span which is subsequently passed on to the ocean and may be problematic. Slow flow systems like groundwater are of more concern as pollution is characterized by a long time. Pollutants make their way into the water supplies through point and non-point sources. Point sources are small identifiable sources like factories and sewage treatment plants. B-point sources are large areas like cities and agricultural fields where rainwater runs over land and after picking pollutants like pesticides (from farming land), animal waste, oil and road particulates from urban areas, acidic material from mines and particulate matter from eroded soil transfers all the pollution to waterbodies like streams, rivers, lakes and even oceans. The increased concentration of elements like nitrogen and phosphorus aggregates the algal life, which in turn depletes the water of oxygen through eutrophication, giving rise to dead zones for fishes and other aquatic life. Containing a greater volume of water from multiple places makes it more difficult to deal with pollution due to non-point sources. In addition, garbage and other wastes are dumped in oceans (marine dumping), making it highly contagious. Incidents like oil spills and leaks also add to water pollution causes. Increased concentration of greenhouse gases that get absorbed in oceans makes it inhospitable for the existence of some creatures.

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2.2.5 Effect of water pollution In an ecosystem “everything is connected to everything else”. The producers produce high-energy compounds through photosynthesis; the consumers feed on the stored energy, and the decomposers feed on the dead organisms and plants to produce stable inorganic compounds. Ecosystems exhibit a flow of energy and nutrients with a perfect balance at each level. Water pollution may lead to irreversible damage to the ecosystem by entering the food chain. Dumping of organic waste due to human activities leads to a spur in N and P levels, increasing algae production. In turn, the algae may clog the fish gills and block sunlight, thereby depleting oxygen and causing water pollution, damaging the ecosystem. It renders the stream anaerobic with the release of more toxic gases like hydrogen sulphide. It leads to a bad odour, dark colour due to fungus growth, and decreased fish life and other aquatic insects. Disease-causing microorganisms called pathogens may cause a variety of intestinal diseases. Around the world, most of the population is exposed to water-borne pollution, and approximately 1.5 million children, mainly in underdeveloped countries, die from water-borne diseases. These rivers are exposed to pathogens through human and faecal waste caused by improper sewage treatment, especially in developing and underdeveloped countries. Oil spills caused by accidents may pollute the air by evaporation of hydrocarbons. Also, it takes many years for bacteria to decompose such oil layers, which harms fish life. Another group of toxic chemicals is heavy metals produced by industry, and at metallic ore mines like lead and mercury may accumulate through the food chain. The worst case of arsenic poisoning occurred in Bangladesh, resulting in 100,000 s of deaths due to water-borne diseases like diarrhoea and cholera due to improper sewage treatment. Also, weathering of minerals rich in mercury causes the injection of this hazardous metal in the water supply, which may further cause health problems like loss of sight, hearing, nervousness and even death as it directly impacts the central nervous system. During a well-known occurrence in Minamata, mercury levels increased due to industrial discharges, and individuals who consumed fish for more than 30 years had a significant mortality toll.

2.2.6 Possible solutions It is a serious issue to resolve this water pollution problem, so today, scientists and researchers are working together for reliable solutions and strategies in different ways [7]. The initiatives taken at the national and international levels, like the Clean Water Act (regulating industrial waste in developed countries) and other regulatory laws, are framed to maintain and restore water quality in countries. The solution not only lies in the improvisation of freshwater quality but also in the progress toward sustainability. The best strategy involves dealing with the problem at the primary level, that is, having proper sewage water treatment plants using different treatment processes like bioremediation and removal of heavy metals and pesticides and harmful organic compounds found in industrial and domestic wastewater. To limit agricultural pollution, latest techniques based on nutrient load limits are employed. In case of oil spill incidents, skimmer ships may be used as a part of clean-up operations for small spill incidents to vacuum oil from the water surface and use detergents to facilitate oil decomposition. As some dispersants may be

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toxic to the ecosystem, bioremediation techniques based on adding microorganisms that specialize in accelerated oil decomposition are also followed. Wetlands also help to moderate the climate conditions at the global level by mitigating the pollution effects by trapping sediments, water and minerals from elevations to the smaller area but also for the development of organisms that compose the lowest level of the food web, contributing to the biodiversity.

2.2.7 Radioactive pollution Radiation is omnipresent on this earth, and all forms of life, including humans, are exposed to it. It is present in the form of cosmic radiation produced in the upper layers of the atmosphere by the collision of solar radiations with the atoms and results in ionized particles and terrestrial radiation, which arises because of radioactive atoms like uranium, thorium, radium and potassium present naturally in rocks and soil. These radiations are also produced artificially in a nuclear reactor or accelerator. Technological advancements have increased the dependence for energy on nuclear reactors, and amid ever rising population, its importance has increased even more. These artificial radioactive sources are widely exploited in medicine and industries like hospitals and pharmaceutical industry; research labs and power reactors; radiography and sterilization, etc. However, the radiation released from the radioactive materials is sufficient to strip the electrons away from the atoms or break the chemical bonds, causing permanent damage to biological functioning and irreparable damage to nature. The major sources of radioactive pollution are nuclear reactors and factories producing nuclear weapons leading to unmanageable radioactive waste. Apart from these, the nuclear tests conducted by different countries added to this pollution resulting in the contamination of the environment. One of the worst nuclear disasters occurred in Chernobyl in 1986 and 2011 in Fukushima, Japan. Thousands of people died due to the radiation released from nuclear plants.

2.2.8 Effects of radioactive pollution Environment contaminated with radioactive pollutants also has myriad ill effects on public health and the ecosystem. Most of these pollutants are carcinogenic and highly toxic, whether produced naturally or artificially. When alpha, beta and gamma radiations interact with the matter, it damages chemical bonds on the way, leading to permanent changes in the cell structure. Direct exposure to these radiations leads to somatic effects and even acute symptoms like severe circulatory damage, nausea and hair loss, followed by death. Such an incident was witnessed in Chernobyl, Russia, in 1986. Exposure for a long time to low doses of radiation may damage the cell’s genetic material. However, the risk of this radiation exposure is also dependent on many other factors like the magnitude of the radiation exposure, time of exposure, penetrating power of radiation, the sensitivity of the organ exposed and the proportion of organs exposed [8]. The radioactive elements find their way to water bodies through radioactive rain and are hazardous to the entire ecosystem after entering the food chain. Plants exposed to that water lead to continuous emission of radiation. The water in the contaminated area is not only unfit for drinking

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but also for other agricultural purposes. Mining may also release these deadly materials into the soil, leading to stunted plant growth and seepage of toxic substances in the groundwater. High exposure to these materials can cause numerous diseases like cancer, reproductive dysfunction, stunted growth and permanent damage to the body’s organs.

2.2.9 Possible solutions Governments must formulate laws and regulatory principles to ensure that nuclear energy is utilized safely and appropriately. Preventive measures include treaties, regulations, standards and technical methods to curb radioactive pollution [9]. There have been international agreements to monitor the technical methods to curb radioactive pollution and their timely implementation and assessment of safety policies as and when required [10 12]. The major objectives set by the International Atomic Energy Agency (IAEA) taking into consideration the protection of human health and the environment include [13] 1. Reduction in the generation of radioactive waste of all kinds to a minimum with the appropriate technological measures, recycling and reusing principles 2. Minimize the spread of radioactivity by containing it to the greatest possible extent 3. Implementation of recycling and reuse policies 4. Use of proper treatment technologies to reduce the amount of radioactive waste Some countries, including France, Germany, Sweden, the United Kingdom and the United States, have limited alpha, beta and gamma emission rates. In addition, further restrictions on total activity, total mass and volume in some of the projects/plants in Belgium, Germany and Sweden have been applied. The ways to control radioactive pollutants should be the same for anthropogenic and natural radionuclides according to the guidelines of the International Commission on Radiological Protection [14]. Being vulnerable to toxic ions, the microorganisms may lead to the concentration and migration of these ions and be practically employed in treating radioactive waste [15].

2.2.10 Noise pollution Noise pollution is any unwanted, unnecessary and stressful noise that affects the physical, mental and social activities of human beings as well as animal life in a harmful way. Noise pollution is inevitable in areas prevailing the human population since several of the human processes or activities like factory/industry machinery, transportation system, construction, spiritual activities and community activity (e.g., television, music systems, machinery, nightlife, social activities, domestic appliances, etc.) generate some sort of noise [16]. Noise is found almost everywhere. Physically, sound and noise are often used as synonyms. Technically, noise is regarded as any undesired sound and/or disturbance within a useful frequency band. A sound is a form of energy produced by vibrating bodies which, upon reaching human ears, produces a form of hearing sensation. All vibrating bodies do not produce sound in the audible range from 20 to 20000 Hz. The intensity of sound is measured in decibels (dB). All the sounds produced outside this range are undesired for normal human hearing. Thus noise is known as the “unwanted sound” and is

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distinguished by the requirement or tendency of the person receiving it. There are mainly three classifications of noise pollution [17] 1. Atmospheric noise: It is also known as static noise, which is the noise occurring due to the natural processes taking place in the atmosphere, like lightning discharges in thunderstorms or other natural electric disturbances. Most of the atmospheric noise is generated in the very low frequency and low frequency range of the radio spectrum. Thus atmospheric noise becomes less severe at the high frequency and very high frequency, where man-made noise dominates mainly in urban areas. 2. Environmental noise: It is the accumulation of noise pollution occurring outside the environment and neighbouring. Many factors may contribute to this type of noise, for example, transportation that uses a motor to make a loud noise (like trains, trucks, cars, helicopters, watercraft, spacecraft and aircraft) and various amusing activities like sports and music performances. The environmental noise depicts the liveliness of human beings and is thus included in most of the daily activities of human life. The random noise of people talking, various alarms, announcements and bioacoustics noise from animals or birds all produce environmental noise. 3. Occupational noise: It is also called industry noise and is defined as the noise received by workers during their jobs. It may be caused by the work environment or the use of machinery and also varies in characteristics like loudness and frequency components. In urban areas, more than half of the total environmental noise pollution is produced solely by traffic noise [18,19]. The traffic noise includes motor noise as well as hornhonking noise. In the last few decades, this extensive increase in traffic noise pollution has occurred because of increased vehicles, low turnover of old vehicles, an underdeveloped road network and increased urbanization. Also, the unnecessary usage of horns and loudspeakers, either for spiritual or political purposes, and the unnecessary usage of firecrackers all these constitute noise pollution and harm human health and social activities.

2.2.11 Effect of noise pollution Continuous exposure to noise causes deviation from the normal functioning of the body. The response to noise may depend on the characteristics of the sound, e.g., intensity, frequency and duration. Low-level noise is not harmful, but severe noise exposure affects the human body emotionally, physiologically and psychologically. The rapid effect of noise exposure could include irritation (annoyance), stress (the human body responds to loud noise by releasing stress hormones such as adrenaline) and nervousness. Long-term noise exposure could slowly lead to complete hearing loss. Noise pollution has also increased human heart and circulation problems (associated with cardiovascular disease). It affects the brain and intelligence due to its hindrance in the learning process (e.g., distracting attention from studies or homework), sleep deprivation/sleep disturbance (e.g., not being able to sleep properly due to loud noise, thereby affecting developmental activities) and feebleness (e.g., loud noise causing the breakdown of concentration and

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self-control) [20,21]. Besides cognitive impairment, long-term exposure to noise is found to cause increased mortality risks and is associated with mental health impairment in the general population.

2.2.12 Possible solutions In a country like India, noise pollution cannot be avoided entirely, but still, some precautions can be taken to stop its extent of pollution. The noise pollution can be controlled at the generation end through the following techniques: 1. Vehicles’ loud and unnecessary noise can be reduced through regular servicing and maintenance and by properly fixing the silencers of automobiles, two wheelers, etc. 2. Limiting the usage of loudspeakers to important meetings/functions only and prohibiting it for all other purposes. 3. In industries, selecting equipment/machines based on advanced technologies that produce less noise will be an important step toward reducing noise pollution in a great way. The regular servicing and stoppage of unnecessary usage of these machines are essential to control noise pollution in industries. 4. Including suitable noise-absorbing material for walls and ceilings in the building’s infrastructure will reduce noise pollution. 5. The creation of a greenbelt can help in decreasing the sound levels. As per the regulations of statutory bodies, the industries are directed to develop greenbelts around four times the built-up area to minimize different pollutants, including noise. 6. Earmuffs, ear plugs, etc., can be used for hearing protection. Ear muffs, widely available in different sizes, shapes and seal materials, can attenuate noise pollution based on their type.

2.2.13 Plastic pollution Plastic pollution is recognized as constantly gathering plastic contaminants into any particular environment to which they are not native. Such environments are undesirably affected by either a direct introduction or degradation process of plastic materials, mainly polymeric systems. Plastic contaminants could be carried away by water bodies or air and transported to remote locations through human intrusion [22]. Most globally, generated plastic waste always finds its way into aquatic environments such as coastal and marine ecosystems through anthropogenic sources. Plastic pollution has become a severe concern in almost all parts of territorial and aquatic ecosystems. Recent data show an increase in global plastic pollution due to personal protective equipment, such as facemasks, to limit the spread of COVID-19 [23]. The accumulated plastics may be broadly classified into three levels based on their size: macroplastics comprise visible items (like single-use packaging), microplastics are particles , 5 mm [24] and nanoplastics , 1µm [25]. In-situ environmental degradation and fragmentation of larger-size plastics may be used to create microplastic and nanoplastic particles [26]. Also, microplastics are commercially exploited in cosmetic products and other

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personal care items. Plastic is an environmental hazard, especially once it fragments into microplastic and nanoplastic, which can occur automatically due to sunlight, biotic interaction and temperature fluctuations.

2.2.14 Effects of plastic pollution Plastic costs humanity trillions of money in terms of environmental and social damage that varies from the toxic chemicals released due to plastics buried in landfills, diffusion of plastic contaminants into the air, soils and water sources, including land value loss due to littering or waste disposal sites. Besides, it has severe harmful effects on human beings through nanoparticles interacting with human cells or exposure to harmful additives in plastic products [27]. Nanoplastics and harmful additives are present in many essential items, such as food/ beverage packaging, primary household products and medical equipment. They enter the human body through ingestion, skin contact or inhalation. Nanoplastics can harm and cause inflammation in human skin, lungs and brain cells [28] and may be linked to cancers [29]. Plastics also secrete damaging endocrine-disrupting chemicals [30] related to diabetes, obesity, reproductive impairment, thyroid dysfunction and endocrine system disorders. In humans, children and infants are susceptible to and therefore greatly affected by plastic contaminants due to increasing exposure to plastic pollutants through ample baby food packaging, feeding bottles and children’s toys. The terrestrial environment is always linked with the aquatic ecosystems; therefore changes in one system cause impacts on another also. Consequently, like the territorial environment, the degree of impact of plastic pollution on marine systems is too severe [31]. Without immediate intervention, in the next 10 years, the world’s aquatic environments would be comprised of more than millions of tons of plastic contaminants [32]. This increased volume of plastic in aquatic environments would displace an equal volume of water, increasing the probability of floods and worsening global warming. All these phenomena have innumerable side effects, such as endangering individuals and communities, abolishing infrastructures, and draining healthcare resources and government budgets, representing the broader impact of plastic pollution.

2.2.15 Possible solutions Firstly, following the antique regulation of prevention is better than cure; environmental duty and sustainability need to be learned since childhood, either through the formal education system or at home or in religious places, as an admiration of nature and life. The next step should be taken to ban the usage of plastic completely. Even though we restrict the production and usage of plastics, we still need to tackle the current plastic pollution in nature, i.e., water, atmosphere, soil and consumables (e.g., table salts). Therefore combined global actions are needed for plastic control and management to overcome the future threats of plastic contaminants on living and nonliving systems. Various courses of action have been taken to achieve this goal. The initiatives such as extended producer responsibility, that is, a strategy to include all of the environmental costs allied to a product throughout the product life cycle into the market price of that

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product, and plastic-related legislation are needed to be incorporated towards a plasticfree environment [22]. The 3Rs of plastic management is a crucial environmentally friendly concept for plastic-free ecosystems, that is, recycle, reuse and reduce. Plastic waste needs to be transformed into a cashable commodity, rewarding recovery and increasing recycling rates. We should switch to greener or ecofriendly alternatives, that is, introduce the concept of “green plastics” such that its degradation in any given environment should either be neutral (i.e., have no net effect) or positive (i.e., easily recyclable or reusable, etc.), that is, in addition to biodegradability, it should include biocompatibility in the environment. Hence, “green plastic” should be an alternative polymer with characteristics comparable to or even superior to conventional polymeric materials but with less environmental impact. Such plastics can be biobased or fossil-based materials.

2.2.16 Soil pollution Soil pollution is recognized as the mixing of elements or particles that alter the soil composition by decreasing its fertility, making it inappropriate for agriculture and prone to drought. Soil pollution arises due to the disposal of industrial waste and radioactive uranium pollutants into the soils, pollution by domestic leftovers, forest fires, volcanic outbursts and others which all have highly toxic contaminants and hazardous chemicals [33]. Most of the agricultural lands are irrigated by rivers polluted with industrial wastewater. These hazardous chemicals thus enter the soil (mostly the top layer of soil) and reduce its fertility and other biological systems of the soil. Besides industries, an important source of pollution is provided by the chemicals composited in pesticides and fertilizers that include hazardous elements. These toxic elements seep into the soil and lead to soil’s poor fertility, thereby causing difficulties in the production of crops and agriculture [34]. With the lack of proper food, this hazardous effect could lead to ecological imbalances. Since toxic and hazardous chemicals pollute the soil and crops, they may give rise to unforeseen health issues for living beings consuming such crops. When acid rain (including sulphuric and nitric acid elements) falls on the ground/soil, it seeps into the soil and hugely alters the soil composition, changing its characteristics. Thus acid rain may cause damage to plants and important microbes that live in the soil, thereby disturbing the biological food chain [35].

2.2.17 Effects of soil pollution In contaminated soil, some pollutants may vaporize and get inhaled by humans or animals, or human beings may make direct contact with the soil. In these ways, unwanted elements enter the human body and affect health. These soil contaminants may penetrate the groundwater acquired for human consumption marking a severe threat to the future generation. The severity of the consequences depends on the duration of pollutants exposure to the human body. Through this pathway, they enter the body, and how strong the exposed pollutant is. For example, continuing exposure to metals such as lead, chromium, etc., pesticides and herbicides may cause cancer and even may originate hereditary disorders. Long-term exposure to benzene at adequate concentrations may lead to leukaemia in

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2. Environmental pollution

humans. Mercury exposure may induce severe kidney damage and may cause some irretrievable diseases. Besides these, there are other health consequences, such as skin rash, headaches, nausea, fatigue, exhaustion, eye irritation, etc., originating from soil pollution [36]. The loss of soil fertility, called desertification, leads to soil and air erosion and transforms agricultural lands, grasslands and forest areas into deserted lands. The disappearance of the fertile soil layer leads to a reduced quantity of grassland that further leads to increasing water erosion which harms the storage capacity of dams, thereby decreasing the irrigation efficiency and enlarging costs for agriculture. Therefore the degradation of forests and other vegetation has become a huge concern to stop environmental degradation and its tendency to cause drought. Moreover, the loss of agricultural lands, an increasing number of dunes and dust storms contribute to increasing air pollution.

2.2.18 Possible solutions Nowadays, all over the world, a trendy way to reduce the risk of pesticides and chemical fertilizers entering our bodies through vegetation and farms is to switch to the organic farming method. Organic farming not only protect agricultural production from chemical adulterations but also protect the soil from pollution. Organic farming restricts the use of chemicals in agriculture to harvest cleaner and safer food for humans and preserve the soil’s natural properties. It also preserves the surrounding environment. The groundwater is polluted due to the contaminated soil and the sewage water used for agricultural purposes must be treated/filtered/cleaned using various techniques before using it in the farms/home to evade the diseases transmitted to humans through the polluted water. This is also required to preserve soil fertility [37]. A variety of other approaches may be adopted to reduce soil pollution: 1. Growing plants (such as willow) to extract heavy metals. The process is called phytoremediation. 2. Using fungus to metabolize contaminants and accumulate heavy metals. The process is called mycoremediation. 3. Surfactant leaching. 4. Remediation of oil-contaminated sediments with self-collapsing air microbubbles.

2.2.19 Light pollution Light pollution refers to the excessive and unnecessary use of artificial light in any form, which has unpleasant effects on living beings, society and nature. Artificial lighting or outdoor lightening sources are used at night to increase the visibility and safety of living beings. This has undoubtedly peaked other activities at night such as increasing lifestyles, construction of newer infrastructure and almost all of the activities which can be done during the daytime that has increased industrial growth and built up the economy [38]. But light also becomes a pollutant when there is an impulsive amount of usage, which causes adverse effects, both directly and indirectly. These effects include glaring, falling stars at night, causing difficulty in astronomical studies, and changes in the

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biological processes among plants and animals [39]. The leading cause of light pollution may be the poor design of the outdoor lights used in residential places, commercial buildings, industries, etc. Most of the lighting sources are designed so that the light spills in the sky rather than being only available on the ground, i.e., in areas that need illumination. These outdoor sources of light severely affect natural light. Besides, the reckless use of light, like switching on the light when not required and keeping it on for long periods, etc., also increases light pollution. This is also one way to waste energy and not contribute to energy management.

2.2.20 Effects of light pollution The increasing outdoor lighting has imposed a severe threat to astronomy [40]. Because of the artificial illumination at nighttime, astronomers find it difficult to view the night sky and observe celestial objects. Thus light pollution greatly hinders exploring the sky and learning new concepts about the night sky. Light pollution negatively affects all living beings—humans, plants and animals. The increasing artificial light significantly affects human physiology by changing the sleep and wake cycles, causing sleep deprivation, reduced sleep, causing stress on the eyes, leading to skin cancer, etc. (Raap et al., 2015). Rapid urbanization makes humans spend most of their time at home/office (indoor), thus reducing the exposure to natural sunlight, which is vital for all of our biological processes and provides other vitamins and nutrients. The biological processes of animal, insect and bird species are also affected by light pollution. The artificial light makes them unconscious of the day night and alters the biological processes like breeding, hatching, nesting and migration. It is known to increase nocturnal vigilance in peahens/peacocks during the night [41]. As a result of the change in the biological cycles, decreases in the population of moths, butterflies, and other insects have also been observed in the past few years [42]. An extreme reduction in pollination in plant species has been observed worldwide as an adverse effect of light pollution at night, causing an ecological imbalance [43]. Plant life is also affected due to the declining number of dark hours, bringing changes in the photosynthesis process which is essential for existence. Besides the health issues and vegetation concerns, increasing dependence on artificial lights also leads to the wastage of energy and its high consumption, causing another worry for difficulty in energy management.

2.2.21 Possible solutions Light pollution is one of the least known types of pollution and the easiest anthropogenic pollution to address and reduce. The simplest way is to use the light efficiently in the required place and leave the rest naturally dark as it is. Also, there is a need to provide proper awareness about the increasing number of artificial lighting and its consequences globally. Public awareness of the light pollution issue can be raised by organizing some campaigns and public-participation-based research. For example, the “Earth hour” and “Dim It Campaign” calls for people to switch off their lights for an hour. We need to

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implement standard lighting guidelines and regulations. Better lighting designs are required such that light is directed efficiently from top to bottom to avoid trespass and light is directed to the atmosphere that leads to skyglow (Table 2.1).

2.3 Switching to sustainable energy “a requirement for the safer environment” Most of the environmental problems can be solved, to an extent, by using sustainable renewables. Sustainable energy is withdrawn from resources that can maintain current operations without endangering future generations’ energy needs or climate. The most well-known sustainable energy sources are wind, solar, hydropower, geothermal and biomass. Sustainable energy may be the solution to our energy and climate needs. The universal response to the problem of air pollution is to switch from fossil fuels to sustainable renewables like solar, wind and geothermal energy. In general, switching to environmentally friendly transportation such as electric vehicles and hydrogen vehicles and encouraging public transport and/or shared mobility like car pooling could reduce air pollution as well as noise pollution to a great extent. From planning to design, construction, maintenance, renovation and demolition, the green building (also known as green construction or sustainable building) design and resource-efficient structures should be approved to reduce TABLE 2.1 Different types of pollution, their sources and the major pollutants. Type of pollution

Sources

Pollutants

Air

Volcanoes, factories, waste disposal landfills, fire, open burning, automobile emissions, crops

Smoke, ash, hydrocarbons, carbon dioxide, dust, methane, dust, CO, aerosol, particulates, nitric oxide

Water

Oil spills, industrial waste, agricultural waste, sediment from land erosion, acidic drainage from mines, anaerobic decomposition

Toxic chemicals and pesticides, organic pollutants, radioactive waste like arsenic and mercury, suspended sediments, oil dispersants

Noise

Airports, road traffic, construction and industrial activities, public address system, firecrackers, rail roads

Noise exceeding the standard levels leads to adverse health consequences

Light

Commercial properties, offices, light trespass, sky glare, clutter

High and varied intensity of artificial light

Plastic

Building and construction, consumer products, Compounds like phthalates, Bisphenol A and packaging, synthetic fibres, plastic groceries, paints polybrominated diphenyl ether and coatings

Soil

Natural anthropogenic soil pollution, industrial waste, inefficient disposal of waste

Radioactive Nuclear weapon production, mining, nuclear accidents, nuclear waste disposal, medical diagnostics, and treatment

Pesticides, heavy metals, hydrocarbons, chlorinated industrial solvents, plasticizers, dioxins Radioactive elements like strontium, uranium, radon

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the wastage of energy and fully utilize sustainable sources. The wastewater recycling project should be incorporated to minimize soil and water pollution. Environmentally friendly products should be encouraged for the benefit of nature and humans and made economically for people. People need to learn the long-term advantage of using these ecofriendly products in daily life.

2.4 Conclusion In this chapter, the concept of pollutants, pollution and its different types like air, water, noise, radioactive and soil pollution are discussed. The anthropogenic activities are mainly responsible for all types of pollution and environmental degradation. Environmental degradation also occurs due to noise and radioactive pollution. The excessive use of natural resources, by-products obtained during natural processes, lack of knowledge and awareness to treat the pollutants and pollution are main contributing factors in polluting the environment. Some pollutants are biodegradable which breakdown easily, while some are nonbiodegradable which do not breakdown. These nonbiodegradable pollutants when introduced with any components present in the environment can convert into another components which remain persistent in the environment for long time. Therefore it is necessary to raise awareness and educate the people about the causes and possible solutions of the pollution apart from implementation of environmental law. Use of ecofriendly technologies can also be effective to treat and manage the pollution caused by anthropogenic activities.

References [1] H.M. Hussam-Husein, M. Kalkha, A.Al Jrdi, R. Ba¨umler, Urban soil pollution with heavy metals in Hama Floodplain, Syria, Nat. Resour. 10 (2019) 187 201. Available from: https://doi.org/10.4236/nr.2019.106013. [2] I.F. Gheorghe, B. Ion, The impact of air pollution on health, economy, environment and agricultural sources, Eff. Air Pollut. VegetatiRole VegetatiReducing Atmos. Pollut., 2011. [3] http://www.businessinsider.my/the-cities-with-the-worldsworst-air-pollution-who-2016-5/. #I3i8Lc4E2OlRyo1a. 99, 2016 (Accessed 12.08.16). [4] WHO report: (http://www.who.int/mediacentre/news/releases/2016/air-pollution-rising/en/ 2016, (Accessed 12.08.16). [5] David J. Thompson, Seasons, global temperature, precession, Science 268 (1995) 59. [6] http://www.scgh.com/featured/green-news/the-cleanest-and-the-most-pollutedcities/ (2016). (Accessed 12.08.16). [7] K. Dorˇsner, 2018, Essent. Environ. Sci. [8] C. Sahut, J.C. Roux, Radioactive pollution, in: C. Ronneau, O. Bitchaeva (Eds.), Biotechnology for Waste Management and Site Restoration. NATO ASI Series, vol 34, Springer, Dordrecht, 1997. Available from: https://doi.org/10.1007/978-94-009-1467-4_6. [9] R.O. Abdel Rahman, M.W. Kozak, Y.T. Hung, Radioactive Pollut. Control. (2014). Available from: https:// doi.org/10.1142/9789814449175_0016. [10] UNSCEAR United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) (2003). Report of the United Nations Scientific Committee on the Effects of Atomic Radiation to the General Assembly, Annex E.

Green Chemistry Approaches to Environmental Sustainability

40

2. Environmental pollution

[11] Euratom. Council Directive 96/29/Euratom of 13 May laying down basic safety standards for the health protection of the general public and workers against the dangers of ionizing radiation, Official Journal of the European Communities L-159 of 29/06/1996, Luxembourg (1996). [12] Canfa Wang, Chinese environmental law enforcement: current deficiencies and suggested reforms, Vt. J. Environ. Law 8 (2007) 159 190. [13] International Atomic Energy Agency. Regulatory Control of Radioactive Discharges to the Environment Safety Guide, IAEA Safety Standards Series No. WS-G-2.3, (2000). [14] International Atomic Energy Agency. Design, Construction, Operation, Shutdown and Surveillance of Repositories for Solid Radioactive Wastes in Shallow Ground, Safety Series No. 63, Vienna: IAEA, (1984). [15] C.M. Hussain, R. Kec¸ili, Environmental pollution and environmental analysis. Mod. Environ. Anal. Tech. Pollut., (2020). https://www.sciencedirect.com/science/article/pii/B9780128169346000011. [16] R. Thompson, R.B. Smith, Y. Bou Karim, C. Shen, K. Drummond, C. Teng, et al., Noise pollution and human cognition: An updated systematic review and meta-analysis of recent evidence, Env. Int. 2022 (2021). Available from: https://doi.org/10.1016/j.envint.2021.106905. Jan. [17] D. Jhanwar, Noise pollution: a review, J. Environ. Pollut. Hum. Health 4 (3) (2016) 72 77. [18] C.M. Hogan, G.L. Latshaw, The relationship between highway planning and urban noise, Proc. ASCE, Urban. Transp. (1973) 21 23. May. [19] M. Omidvari, J. Nouri, Effects of noise pollution on traffic policemen, Int. J. Env. Res. 3 (4) (2009) 645 652. [20] O. Hahad, J.H. Prochaska, A. Daiber & T. Muenzel, Environmental noise- induced effects on stress hormones, oxidative stress, and vascular dysfunction: key factors in the relationship between cerebrocardiovascular and psychological disorders. Oxid. Med. Cell. Longev. (2019) [21] S. Stansfeld, C. Clark, Health effects of noise exposure in children, Curr. Environ. Health Rep. 2 (2015) 171 178. [22] A. Forrest, L. Giacovazzi, S. Dunlop, J. Reisser, D. Tickler, A. Jamieson, et al., Eliminating plastic pollution: how a voluntary contribution from industry will drive the circular plastics economy, Front. Mar. Sci. 6 (2019) 627. Available from: https://doi.org/10.3389/fmars.2019.00627. [23] A.O.C. Iroegbu, S.S. Ray, V. Mbarane, J.C. Bordado, J.P. Sardinha, Plastic pollution: a perspective on matters arising: challenges and opportunities, ACS Omega 6 (30) (2021) 19343 19355. Available from: https://doi. org/10.1021/acsomega.1c02760. [24] V. Hidalgo-Ruz, L. Gutow, R.C. Thompson, M. Thiel, Microplastics in the marine environment: a review of the methods used for identification and quantification, Environ. Sci. Technol. 46 (2012) 3060 3075. Available from: https://doi.org/10.1021/es2031505. [25] J. Gigault, A.T. Halle, M. Baudrimont, et al., Current opinion: what is a nanoplastic, Environ. Pollut. 235 (2018) 1030 1034. Available from: https://doi.org/10.1016/j.envpol.2018.01.024. [26] J. Wang, L. Zheng, J. Li, A critical review on the sources and instruments of marine microplastics and prospects on the relevant management in China, Waste Manag. Res. 36 (10) (2018) 898 911. [27] M. Revel, A. Chaˆtel, C. Mouneyrac, Micro(nano)plastics: a threat to human health? Curr. Opin. Environ. Sci. Health 1 (2018) 17 23. Available from: https://doi.org/10.1016/j.coesh.2017.10.003. [28] R. Lehner, C. Weder, A. Petri-Fink, B. Rothen-Rutishauser, Emergence of nanoplastic in the environment and possible impact on human health, Environ. Sci. Technol. 53 (2019) 1748 1765. Available from: https://doi. org/10.1021/acs.est.8b05512. [29] R. DeMatteo, M.M. Keith, J.T. Brophy, A. Wordsworth, A.E. Watterson, M. Beck, et al., Chemical exposures of women workers in the plastics industry with particular reference to breast cancer and reproductive hazards, N. Solut. 22 (2013) 427 448. Available from: https://doi.org/10.2190/NS.22.4.d. [30] J.T. Brophy, M.M. Keith, A. Watterson, R. Park, M. Gilbertson, E. Maticka- Tyndale, et al., Breast cancer risk in relation to occupations with exposure to carcinogens and endocrine disruptors: a Canadian case control study, Env. Health 11 (2012) 87. Available from: https://doi.org/10.1186/1476-069X-11-87. [31] M. Bergmann, F. Collard, J. Fabres, et al., Plastic pollution in the Arctic, Nat. Rev. Earth Env. 3 (2022) 323 337. [32] S.B. Borrelle, J. Ringma, K.L. Law, et al., Predicted growth in plastic waste exceeds efforts to mitigate plastic pollution, Science 369 (2020) 1515 1518. [33] J. Paz-Ferreiro, G. Gasco´, A. Me´ndez, S.M. Reichman, Soil pollution and remediation, Int. J. Env. Res. Public. Health 15 (8) (2018) 1657. Available from: https://doi.org/10.3390/ijerph15081657.

Green Chemistry Approaches to Environmental Sustainability

References

41

[34] S.H.H. Al-Taai, IOP Conf. Ser.: Earth Environ. Sci 790 (2021) 012009. [35] S. Chen, X. Shen, Z. Hu, H. Chen, Y. Shi, Y. Liu, Effects of simulated acid rain on soil CO2 emission in a secondary forest in subtropical China, Geoderma 189 190 (2012) 65 71. [36] European Commission. Science for Environment Policy, Soil Contamination: Impacts on Human Health, University of the West of England (UWE). (2013) 5 p. 5. [37] J. Taher, Environmental pollution - waste management and treatment - Assiut Journal of Environmental Studies. 33, (2009), pp.123,133. [38] M.I. Azman, M.N. Dalimin, M. Mohamed, M.F. Abu Bakar, IOP Conf. Ser.: Earth Environ. Sci. 269 (2019) 012014. [39] K. Kaushik, S. Nair, A. Ahamad, Studying light pollution as an emerging environmental concern in India, J. Urban. Manag. (2022). Available from: https://doi.org/10.1016/j.jum.2022.05.012. [40] K.W. Riegel, Light pollution: outdoor lighting is a growing threat to astronomy, Science 179 (4080) (1973) 1285 1291. Available from: https://doi.org/10.1126/science.179.4080.1285. [41] J.L. Yorzinski, S. Chisholm, S.D. Byerley, J.R. Coy, A. Aziz, J.A. Wolf, et al., Artificial light pollution increases nocturnal vigilance in peahens, PeerJ 3 (2015) e1174. Available from: https://doi.org/10.7717/peerj.1174. [42] H. Solano Lamphar, M. Kocifaj, Light pollution in ultraviolet and visible spectrum: effect on different visual perceptions, PLoS One 8 (2) (2013). Available from: https://doi.org/10.1371/journal.pone.0056563. [43] E. Knop, L. Zoller, R. Ryser, C. Gerpe, M. Hhorler, C. Fontaine, Artificial light at night as a new threat to pollination, Nature 548 (7666) (2017) 206 209. Available from: https://doi.org/10.1038/nature23288.

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C H A P T E R

3 Toxicity of polyaromatic hydrocarbons and their biodegradation in the environment Shanky Jindal, Yogita Chaudhary and Kamal Krishan Aggarwal University School of Biotechnology, Guru Gobind Singh Indraprastha University, New Delhi, India

3.1 Introduction Continuously growing anthropogenic activities in urban cities and increase in industrialization has given rise to harmful pollutants at exponential rate [1]. These pollutants contain organic compounds in their structures. These compounds are either arranged in linear, angular or cluster arrangement and contain two to five aromatic rings termed as polycyclic aromatic hydrocarbons (PAHs) [2]. PAHs are recalcitrant with different structures and toxicity [3]. Two or three aromatic ring containing compounds are referred as low molecular weight (LMW) PAHs having the molecular weight range from 128.1 to 178.2 g/mol for example naphthalene, acenaphthylene, acenaphthene, phenanthrene, anthracene and fluorene [4]. Presence of LMW-PAHs in high concentration, greater exposure with long-term toxicity and persistent nature in environment makes them listed in the “United States Environmental Protection Agency” (USEPA) top 16 priority pollutants (Table 3.1) along with high molecular weight (HMW) PAHs [5,6]. More than four aromatic ring containing compounds present in particulate phase are referred as HMW-PAHs. HMW-PAHs are characterized as less soluble in water, increase solubility in organic solvents, more lipophilic, less bioavailability in environmental matrices, high boiling point and are stable in environment for long time and have molecular weight range from 202.3 to 276.3 g/mol, for example, fluoranthene, pyrene, Benz[a]anthracene, chrysene, benzo[b] fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, benzo[g,h,i]perylene, dibenz[a,h] anthracene and indeno[1,2,3-c, d]pyrene [7].

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3. Toxicity of polyaromatic hydrocarbons and their biodegradation in the environment

TABLE 3.1 USPEA top 16 listed polycyclic aromatic hydrocarbons with their toxicities [8]. Polycyclic aromatic hydrocarbon

No. of aromatic rings

Naphthalene

2

Phenanthrene

Toxicity

Reference

128.1

Haemolytic anaemia, liver damage, neurological damage, cataract, retina damage

ATSDR (1995)

3

178.2

Risk of skin cancer, cytogenetic instability, DNA damage

[9]

Anthracene

3

178.2

Affects skin, blood, stomach, intestines and lymph system, cause oedema, itching

ATSDR (1990)

Acenaphthene

3

154.2

Irritate skin, eye, nose, throat, affect liver, and kidney, bronchitis, cough

[10]

Acenaphthylene 3

152.1

Oxidative stress in children, genotoxicity

Pubchem (9161)

Benz[a] anthracene

228.3

Cancer in liver, lung, skin and other tissue

[11]

4

Chemical structure

Molecular weight (g/mol)

(Continued)

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3.1 Introduction

TABLE 3.1 (Continued) Polycyclic aromatic hydrocarbon

No. of aromatic rings

Pyrene

4

Chrysene

Chemical structure

Molecular weight (g/mol)

Toxicity

Reference

202.2

Risk of skin cancer, cytogenetic instability, DNA damage

[9]

4

228.2

Probable human carcinogen, induce aryl hydrocarbon hydroxylation, skin carcinoma malignant lymphoma in mice, chromosomal abnormalities in hamster

Pubchem (2810)

Fluorene

4

166.2

Uterine carcinosarcoma, uterine fibrosarcoma, granulocytic leukaemia, pituitary adenomas

Pubchem (6853)

Dibenz[a,h] anthracene

5

278.5

Pubchem Probable human (5889) carcinogen, neuroblastoma risk in child, induce unscheduled DNA synthesis with metabolic activation, squamous carcinoma, immunosuppressive effects

(Continued)

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3. Toxicity of polyaromatic hydrocarbons and their biodegradation in the environment

TABLE 3.1 (Continued) Polycyclic aromatic hydrocarbon

No. of aromatic rings

Benzo[b] fluoranthene

5

Benz[a]pyrene

Chemical structure

Molecular weight (g/mol)

Toxicity

Reference

252.3

Lung cancer in hamster, carcinoma in female rats, abnormal sperm function mice, benign lung tumour in male

Pubchem (9153)

5

252.3

Cancer in liver, lung, skin and other tissue

[11]

Benzo[k] fluoranthene

5

252.3

Possible carcinogen, Pubchem squamous cell (9158) carcinoma in female rats

Fluoranthene

6

202.2

Mutagenic, carcinogen, compromise Blymphopoiesis

Pubchem (9154)

(Continued)

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3.1 Introduction

TABLE 3.1 (Continued) Polycyclic aromatic hydrocarbon

No. of aromatic rings

Indeno[1,2,3-c, d]pyrene

6

Benzo[g,h,i] perylene

6

Chemical structure

Molecular weight (g/mol)

Toxicity

Reference

276.3

Child neuroblastoma risk

Pubchem (9131)

276.3

Genotoxicity

Pubchem (5889)

Source: From Kim, S., Chen, J., Cheng, T., Gindulyte, A., He, J., He, S., et al. (2019). PubChem in 2021: new data content and improved web interfaces. Nucleic Acids Res., 49(D1), D1388 D1395.

Natural sources of PAHs are volcanic eruption and forest fire [2]. The incomplete combustion during anthropogenic exploitation of resources [4], biomass burning and agricultural waste burning, application of pesticides during agricultural practices [12], production of chemicals, household products and exhaust from vehicles are major sources of PAHs [2]. Among all these sources anthropogenic actions produce PAHs in much higher concentrations. Coal tar, mineral oil effluents and oil spills are major sources of contamination of water bodies, and affect aquatic life. The main source of contamination in soil is deposition from air. Jet aircraft exhaust emits PAHs in very high concentration, and it is a major source of benzo[a]pyrene, which is responsible for high concentration of PAHs in vegetation and soil near airports [13]. Based on their origin, PAHs are categorized as (1) pyrogenic, (2) petrogenic, and (3) biological [14]. Pyrogenic PAHs are formed under high temperature (350 C) and anaerobic condition [15]. PAHs are also formed at lower temperatures. Crude oil contains PAHs that are produced at low temperatures (100 C 150 C) over millions of years [16]. Pyrogenic PAHs are produced by the conversion of coal to other forms of fuels, fuel combustion in automobiles, incomplete wood combustion in agriculture and forest fires, and fuel combustion in heating systems [17]. The high temperature processing of crude oil results in production of petrogenic PAHs [18]. These are released into environment during storage,

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transportation, and use of crude oil and its products. Other sources are oil spills in water bodies, leaks from storage tanks, release of gasoline and motor oil during transportation [19]. Pyrogenic and petrogenic PAHs can be differentiated based on structure differences favoured by different time and temperature conditions. Due to high temperature, pyrogenic PAHs have fewer alkylated rings than petrogenic PAHs, whereas due to extensive time, five-membered rings are abundant in petrogenic PAHs as compared to pyrogenic PAHs [2]. PAHs obtained from power plant site will have different structural pattern than PAHs obtained from oil spill site [16]. Despite toxic effects, PAHs seem inescapable in our life due to their prevalence in commonly used items. Individual PAHs have different health consequences [1]. They are known to be mutagenic, potentially carcinogenic, show teratogenic effects, and immune toxic to various organisms, aquatic life and birds [20], and destroy RBC if inhaled or swallowed. Anthracene and benzo[a]pyrene cause irritation in both animals and humans, and are associated with long-term health consequences such as kidney and liver damage, respiratory issues, and immune system suppression [21]. PAH detoxification occurs primarily in mammals livers, and is initiated by cytochrome epoxide glutathione conjugates [22]. It produces a number of intermediates that form cross-linkages with DNA [23]. PAHs also affect hormones that play role in reproduction and the aromatase enzyme [24]. Benzo [a]pyrene has been reported to cause infertility in males [25]. PAHs exposure during pregnancy promotes adverse foetal growth like reduced development, premature delivery and heart-related complications according to the Centre for Children’s Environmental Health [26]. PAH exposure during pregnancy has been associated with a cognitive disability, increased behaviour problems and may cause asthma in early stages of infant growth [27]. Exposure to LMW- and HMW-PAHs like naphthalene, benzo[a]anthracene and benzo [a]pyrene has been linked to embryo toxicity in experimental animals. These chemicals may bind directly to oestrogen and androgen receptors and cause reproductive effects. Alteration in spermatogenesis, testicular functionality, egg viability, ovarian damage, oxidative damage to DNA in oocytes and other reproductive illnesses are all possible. In human they are responsible for polycystic ovarian syndrome, ovulation, unexpected abortion and premature birth in humans [24]. Various remediation strategies have been used to reduce contaminants in the environment until acceptable levels are reached [28]. PAH pollution is a major global concern due to its negative consequences. Various remediation solutions, including physical, chemical, and biological procedure, have been used to repair the environment from PAH pollution [1]. Due to various limitations of physiochemical approaches, biological methods have become favourite for degradation of PAHs. In ex-situ bioremediation, contaminated material is transported to a different site and then treated. And during in-situ bioremediation, it is carried out on the site of contamination. In-situ remediation is more favourable as they are less expensive, have on-site field application, can cause minimal damage to industrial sites and safe for the environment, and have a higher success rate of eliminating waste [29]. Microbial PAH remediation (bioaugmentation and bio stimulation) involves the use of bacteria, archaea and other microorganism individually or in combination [28]. However, biodegradation using bacteria and fungi is more extensively researched. Bacterial degradation of PAHs can be achieved under aerobic or anaerobic conditions [30]. Under aerobic

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bacterial aromatic hydrocarbon degradation, O2 acts as electron acceptor and cosubstrate for cleavage of the benzene ring, while in anaerobic degradation, the aromatic ring is broken and opened in a completely different way. During aerobic PAH degradation, oxygenase enzymes catalyse the hydroxylation of aromatic rings to form cis-dihydrodiol, which is then oxidized to diol intermediates by dehydrogenase enzymes. These diol intermediates can form catechol, dihydrobenzoic acids and protocatechuic acid that eventually get degraded to intermediates of TCA cycle. Bacterial PAH degradation forms transdihydrodiols under aerobic conditions and nitrate and sulphate under anaerobic reducing conditions [30 32]. Either single pure cultures or mixed bacterial culture and use of microbial consortia techniques for the degradation of PAHs have been described in the literature [33,34]. Mixed bacterial cultures as well as bacterial consortia generally achieved increased or total PAH degradation because of collaborative catabolic activity among members and the presence of several degradation pathways [35]. Thus recent focus is on PAH breakdown using mixed bacterial cultures and consortia. Microbial degradation of PAHs is influenced by the type of PAHs, polluted material qualities, ambient conditions and microbial ecology. Biotic and abiotic factors that play role in the success of microbial bioremediation of PAHs are ambient temperature and pH, concentration of salts (salinity), humid environment, specific nutrient requirement, aerobic/anaerobic conditions, pollutants and heavy metals bioavailability in soil, pre-exposure and concentration of pollutants, microbial diversity and substrate specificity of native microflora towards pollutants, and addition of biosurfactants which aid in degradation.

3.2 Polycyclic aromatic hydrocarbons in the environment PAHs are carbon and hydrogen containing compounds also referred as hydrophobic organic contaminants (HOC). These compounds consist of carbon and hydrogen arranged in either linear or angular orientation and have more than one carbon moiety [36]. Accordingly, they are classified as LMW- or HMW-PAHs. Eventually, these PAHs make their way in environment from different sources being naturally derived from volcanic eruption or from anthropogenic sources like vehicular emission and fossil fuel burning [37]. The PAHs when generated due to incomplete combustion or pyrolysis or petrogenic activities will impact the surrounding ecology and stays for longer time [17]. These PAHs are also restricted to degradation on their own. PAHs are ubiquitous in the environment because they are dispersed primarily through the atmosphere, which receives the majority of the PAHs environmental load. Because most PAH emitters are found in or near urban areas, urban environments tend to have higher concentrations of PAHs than rural environments [12]. PAHs are found in either vapour phase or in solid phase [38]. PAHs with low vapour pressures absorbed to particles in air more readily than PAHs with greater vapour pressure [39]. Due to variations in the vapour pressures of distinct PAH compounds, different PAHs present in various concentrations in the vapours and other sorbet phases [40]. PAH concentration is substantially higher in vapour phase than in the particle phase [40]. The adhesion of PAHs onto particle phases is affected by humidity [41]. The suspended particles type has an impact on PAH adsorption [42]. Because the bulk of PAHs in

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the soil will be attached to sand particles [43], the sorbent size of the particles and the porosity of the soils will be the most critical parameters determining PAH aerosol mobility in the subsurface. Movement of PAHs in environment will be reduced if particles to which they are adsorbed cannot travel through the soil [2]. The octanol water partitioning coefficient of PAHs plays a significant role in influencing PAHs sorption in soils. The aqueous solubility of PAHs depends upon octanol water partitioning coefficient (Kow) [44]. The aqueous solubility reduces as the Kow rises and chance of adsorption of PAHs to a specific soil rises. Thus the Kow and aqueous solubility of PAHs in soil can have an impact on their mobility. Other factor that affects PAH transport includes soil conductivity. Similarly, they are deposited in the sediment environment and can deposit at all levels of lakes [45]. PAHs are rather stationary once incorporated into sediments due to their nonpolar character and less aqueous solubility. However, LMW-PAHs are available to biological organism due to their limited solubility [46]. PAH gas to particulate phase partitioning ratio depends on ambient temperature as well as volatility of compound, as the temperature increases, concentration of PAHs in vapour phase increases [47]. Existential state of PAHs determines distance over which it can travel, like PAHs in gas phase can be transported over long distance, whereas particulate phase PAHs settle down near source of emission [48].

3.3 Toxicity of polycyclic aromatic hydrocarbons PAHs are molecules of concern due to their specific toxicities. Toxicity in aquatic species, marine life and birds is influenced by dose, metabolism and photooxidation of PAHs. They are hazardous to terrestrial invertebrates and are responsible for tumours, reproductive disorder, maturation and immune suppression as negative consequences on various organisms. The carcinogenicity of PAHs is the most worrying toxicity [12]. Because of their hydrophobicity, they can be easily carried into cells and activate gene expression in the cytochrome P450 (CYP) enzyme group [49]. PAHs are metabolized by expressed CYP enzymes into intermediate metabolites which can bind to DNA and cause mutations or cancer.

3.3.1 Toxicity in environmental matrices Behaviour of PAHs in atmosphere depends on their physiochemical reactions, photochemical transformation, wet and dry deposition and their interaction with other pollutants [6,47]. LMW-PAHs are less toxic and more volatile than HMW-PAHs, but they can react with other pollutants to form compounds of higher toxicity, like they react with sulphur dioxide to form sulfuric acids, nitrogen oxide to form nitro- and dinitro-PAHs and ozone to form di-ones [47,50]. PAHs can enter into food chain by contaminated fruits, vegetables, fish, and meat. PAH contamination has been reported in roasted peanuts, tea, coffee, cereals, refined oil and many other foods. Some crops, like rye, wheat and linden, can inappropriately absorb PAHs from soil, air and water [48,51]. Plants can adsorb PAHs from air by stomata on

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epidermis while fruits can adsorb PAHs directly from particles through their hydrophobic surface layer [48]. Adsorption of organic compounds depends on plant morphology; large surface area facilitates pollutant adsorption. Cabbage, maize, tomato and grape leaves were tested for PAH content in an area where a chemical factory caught fire a week before, cabbage and maize leaves (which have larger surface area) were found to contain higher PAHs concentration than tomato and grape leaves [48]. Agricultural and animal products get contaminated during growth (depending on environment), transportation and storage [48]. In Cachaca, a sugarcane beverage, different concentrations of PAHs were present due to different storage conditions (24 months at room temperature), 49.24 mg/L average PAH concentration in polyethylene containers, whereas 6.89 mg/L average PAH concentration in glass bottles. Meat products contamination contribute 54% 71% to daily intake of PAHs through ingestion [48]. Fish is a major consumed protein today; however, both wild and farmed fish gets exposed to pollutants like heavy metals. Bioaccumulation and biomagnification of PAHs in the food chain and aquaculture feed is the main source of exposure to pollutants for farmed fish [52].

3.3.2 Toxicity on humans 3.3.2.1 Carcinogenicity USEPA has classified several PAHs as human carcinogen. Reactive metabolites of PAHs like dihydrodiols, epoxides have higher carcinogenicity than their parent PAH compounds, as they bind with cellular DNA and proteins and cause higher toxicity and leads to mutation, cancer and developmental malformations [47]. Information regarding carcinogenic effect of PAHs is available only from occupational exposure such as during coke production, coal gasification, oil refining and coal tar industry. In coal tar industry, workers using tar were exposed to PAHs and significant number of these workers developed skin cancer [53]. The elevated prevalence of lung cancer in coke oven workers has been found in epidemiological research. Prevalence of cancer was dependent on time spent on near the smoke released from oven, where benzo[a]pyrene concentration has been reported as 30 mg/m3 [47]. Kamangar et al. [54] found that PAHs in yerba mate leaves increased the chances of cancers of oesophagus, larynx, oropharynx, kidney, bladder and lungs. Animal studies showed increased incidences of skin, bladder, lung, stomach and liver cancer. Studies have shown that PAHs can affect hematopoietic and immune systems and can lead to developmental, neurologic and reproductive disorders [47]. 3.3.2.2 Teratogenicity PAHs like benzo[a]pyrene, benzo[a]anthracene and naphthalene pose significant teratogenic effects in pregnant women [47]. Kristensen et al. [55] found that intake of high concentration of benzo[a]pyrene during pregnancy lead to lower weight and birth defects in mice offspring. US Centre for Children’s Environmental Health (CCEH) studies revealed that during pregnancy, exposure to PAH pollution leads to premature delivery, delayed child development and low weight of foetus [56]. Prenatal exposure to PAHs also leads to behavioural problems, low IQ and child asthma. Ren et al. [56] studied the correlation of PAHs in pregnant women and neutral tube defects (NTDs) in new born and found that

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high placental PAH concentration increased the risk of NTDs in new born by 45 times. Phenanthrene was found in highest concentration in placenta along with nine other PAHs. Yuan et al. [57] observed that higher PAH-DNA adduct levels increased the risk of NTDs by three times, while lower adduct levels combined with high placental PAH concentration increased the risk of NTDs in new born by ten times. 3.3.2.3 Genotoxicity PAHs such as chrysene, benzo[a]pyrene and fluoranthene exhibit genotoxicity on incubation with exogenous metabolic activation mixture; however, evidences of their genotoxic nature are limited. However, benzo[a]pyrene, chrysene and benzo[a]anthracene cause chromosome aberration inducing germ cell defects [47]. In epidemiological studies of workers exposed to significant level of PAHs (including benzo[a]pyrene), DNA adducts of benzo[a]pyrene have been found [47]. 3.3.2.4 Cardiotoxicity According to WHO, coronary heart disease is the leading cause of human death. Earlier tricyclic PAHs like phenanthrene were ignored because of low or no carcinogenicity but later cardiotoxic effects of phenanthrene were seen in pink salmon (Oncorhynchus gorbuscha) [18]. Mammalian studies have shown that tricyclic PAHs like dibenzothiophene, phenanthrene induces cardiac arrhythmias; aggravate heart failure, myocardial infarction and other ischemic/atherosclerotic complications [18]. Smoking exposes to high level of PAHs (especially phenanthrene) that increases atherosclerosis risk as well as causes endothelial cell apoptosis [18]. Atherosclerosis is a disease in which build-up of fatty plaques get deposited in artery walls leading to narrowing of arteries. Phenanthrene exposure induces arrhythmias, including bradycardia in fishes. On exposure to 5 nM phenanthrene for 72 h, arrhythmia was observed in zebra fish [58]. Bradycardia was observed in cats after oral administration of high dose of phenanthrene [18]. Phenanthrene disturbs Ca12 influx in fish myocytes by inhibiting L-type calcium channels. This alters Ca12-dependent gene expression in early larval stages of fish including signalling pathways [18]. Downstream effect of abnormal gene expression and circulatory defects can cause irreversible morphological changes [18]. Huang et al. [59] observed cellular hypertrophy (increase in cell size due to increase in amount of cytoplasm or increase in number or size of cytoplasmic organelles) in H9C2 rat cardiomyoblasts on exposure to phenanthrene. 3.3.2.5 Transgenerational effects Transgenerational effects are heritable epigenetic changes that occur by DNA methylation, DNA phosphorylation, DNA acetylation or changes in histone protein structures. Environmental factors like pollutants can alter epigenetic programming in somatic and germ cells. In somatic cells it affects only that individual but if it occurs in germ cells then it is carried on to subsequent generations [5]. PAHs can produce transgenerational effects by epigenetic modifications in somatic and germ cell lines [60]. Smoking can cause DNA methylation alteration in lung tissues, which leads to development of lesions and ultimately tumorigenesis [24]. Smoking in pregnant woman can alter DNA methylation in foetus that can affect nervous system development and brain development, or early onset of diseases like obesity, asthma and reduced fecundity [60].

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3.3.2.6 Ecotoxicity Because of recalcitrant nature, PAHs can bioaccumulate and cause toxicity to marine and terrestrial organisms [17]. They can lead to development of tumours and can also cause reproductive, immunity and developmental defects. Toxicity of PAHs is affected by metabolism and their toxicity increases in the presence of UV light [61]. Plants can absorb and translocate PAHs to other parts by their roots and leaf system. Concentration of PAHs, soil type, water solubility and physiochemical state affects the uptake rate of PAHs. In mammals, effect of PAHs depends on concentration, toxicity, exposure period and routes of exposure such as inhalation, absorption or skin touch [47].

3.3.3 Toxicity of polycyclic aromatic hydrocarbons on birds, amphibians and aquatic animals Aquatic and terrestrial birds get exposed to different types of PAHs in different concentration [62]. Terrestrial birds get exposed to PAHs from diet and atmospheric deposition, whereas aquatic birds get exposed from oil spills, diet and atmospheric deposition with diet as the main route of exposure for birds. Birds possess two forms of aryl hydrocarbon receptor: AHR1 and AHR2. AHR1 is dominant form in birds, catabolizing PAHs in a similar manner as mammals [49]. Effect of exposure to PAHs depends on species and age of birds as well. When young birds ingested oil, it led to stunted development, while in adults, it causes changes in osmoregulatory abilities, hepatic enzyme function, corticosterone levels, adrenocortical function, reduced egg shell thickness and anaemia [63]. Chicken (Gallus gallus) is found to be most sensitive species to DLCs (dioxin-like compounds) along with PAHs, far more sensitive than other species like the mallard (Anas platyrhynchos) [62]. Oil spills is the most harmful pollution for birds, it sticks to feathers of birds and disrupts their water repelling properties, due to which water penetrates into feathers and air insulating layer gets disrupted that leads to hypothermia. It also disables buoyancy capability of birds during swimming. Even in small concentration, it can severely affects egg structure, development of embryo as well as hatching success [64]. Amphibians, especially frogs, are used as indicators in determining environmental pollution due to their contact with both water and soil during their lifetime. Ability to breathe through skin gets affected by deposition of xenobiotic compounds on their skin [65]. All amphibians start their life as eggs in water bodies and later by metamorphosis become adults. Alteration in metamorphosis timeline and physical mutation or development outcomes are indicators of exposure to toxic environmental pollutants like PAHs [66]. Toxicity of PAHs in amphibians differs from mammals because of low-binding affinity of PAHs to aryl hydrocarbon receptors, which affects metabolism as well as excretion of these compounds [67]. Hersikorn and Smits [68] showed delayed metamorphosis (75 days from 52 days) and altered thyroid status in tadpole of frog species exposed to wetlands contaminated with oil spills. These can also damage DNA leading to tumour and cancer formation. Adverse impact of PAHs depends on species and developmental stage of amphibians [65]. Rana temporaria eggs showed significantly high mortality rate on exposure to naphthalene, phenanthrene and pyrene [62].

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Reptile species are declining at a significant pace, and environmental pollution is one of the major threat to their population. Reptiles get exposed to pollutant by ingestion, inhalation or dermal contact [61]. Jones et al. [69] reported that snake skin can accumulate PAHs. Due to significant differences between physiology of humans and reptiles, they are rarely used for studying effect of environmental pollutants [68]. Reptiles xenobiotic catabolism ability responds slowly, but it possesses lower catabolic activity and gets induced to lesser extent [62]. This limits the scope of catabolism of xenobiotic compounds in reptiles. Fish gets exposed to PAHs by diet, respiration and dermal exposure [56]. Transformation of PAHs in aquatic animals depends on rate of uptake, physical conditions, metabolic capabilities, age and feeding strategies [60]. Metabolization of PAHs depends on fish species, their enzymatic activities and type of pollutant. In fish, PAHs are metabolized readily by action of Cytochrome P4501A, which converts them into epoxides. These are short-lived reactive metabolites that nonenzymatically get hydrolysed into phenols and dihydrodiols. Epoxides conjugate with glutathione by action of glutathione-Stransferase and excrete with urine or are secreted in bile for elimination by gastrointestinal tract [18]. Due to rapid elimination of PAHs in fishes, they are present in low concentration in muscles or other tissues. Bile and urine are used as biomarkers for determining exposure to PAHs [17,61]. Reduction in growth on exposure to PAHs changes the lipid metabolism. Rice et al. [70] recorded a substantial weight reduction in juvenile English sole fed on polychaete worms, grown on PAHs containing sediments. Meador et al. [67] reported reduction in lipid and triacylglycerol content in juvenile Chinook salmon upon exposure to PAHs. Connelly and Means [71] observed when bluegills (Lepomis macrochirus) were exposed to either tworinged PAHs or three-ringed PAHs, their immune response was either induced or suppressed. Fluorene, phenanthrene and dibenzothiophenes cause phototoxicity, cardiac specific toxicity during the embryonic process and cardiac malformation to developing fish larvae. PAHs can disrupt endocrine function by either influencing steroid production or interacting with aryl hydrocarbon receptor or other responsive elements like oestrogen responsive element, cAMP responsive element or other nuclear receptors [72]. Exposure of PAHs reduces oestradiol production by ovaries in fishes, suppressing vitellogenesis, ovarian growth, fecundity and atresia [61]. In male fish, PAH exposures lead to reduced androgen level and reduced testicular development. Khan [65] observed a reduction in gonadosomatic index (gonad mass as a proportion of total body mass), disruption in sperm production and testicular development upon exposer to crude oil, in Atlantic cod.

3.3.4 Toxicity of polycyclic aromatic hydrocarbons on plants PAHs can enter in plants through root or leaf system (by deposition on waxy leaf cuticle or by stomata). However, there are other pathways as well like shoot uptake via root and shoot uptake via air or soil [73,74]. PAHs uptake and distribution depend on their structure, concentration, physical properties (adsorption process and solubility) plant type, soil type, organic content of soil and metrological factors [75,76]. As the number of benzene ring increases in PAHs, it becomes more hydrophobic that are rarely absorbed by root system [62]. Movement of PAHs in soil plant systems occurs due to their high

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coefficient of octanol water partition coefficient and poor solubility [73]. PAHs with low octanol water partition coefficient accumulate via roots and translocate to other tissues, whereas PAHs with high octanol water partition coefficient (hydrophobic) adsorbs strongly on root epidermis and is unlikely to penetrate inner roots [77]. Atmospheric PAHs like phenanthrene and naphthalene are taken up by stomata and get accumulated in plant intercellular tissues [75]. PAHs can either get accumulated in membrane lipid layers from atmospheric exposure or move to cell membranes as water-soluble phenanthrene derivatives that damage and increase membrane permeability. PAH contamination can damage membrane structure and function and disturb photosynthetic activity [78]. PAHs are photosensitive compounds; their phototoxicity increases upon exposure to solar radiation by two processes: photomodification and photosensitization. In photomodification, PAHs get converted into different oxygenated products that are more toxic than parental compounds. In photosensitization process, PAHs absorb solar radiation (especially UV radiation) in cells and produce reactive oxygen species (ROS) like superoxide radical, singlet oxygen and hydrogen peroxide (H2O2) [79]. In plants, PAHs get modified by redox or hydrolysis reaction and resulting structures may bind to sugars, glutathione and organic acid and increase their solubility and potential to bind with transporters, enzymes and proteins [62]. HMW PAHs remain persistent in soil and prevent availability of water and nutrients to plants. They also eliminate microbial species in rhizosphere that promotes plant growth [62]. Oil spill leaves crude oil deposit on surface of plants limits water, nutrient and microbial availability, and also prevents transpiration and photosynthesis. PAHs content increases three to five times in yellowing leaf [62]. PAHs hinder the development of root and seedlings, decrease root hair formation, and cause root deformity, late blooming, chlorosis and necrotic white spots. LMW-PAHs like phenanthrene, pyrene and fluoranthene content in healthy and diseased (yellowing) spruce trees fund more PAHs in tissues of damaged needles of the tree as compared to healthy needles. PAHs concentration in tissues of plants varies with season. Stress induced by PAHs exposure is indicated by amino acids like proline, methionine and phenylalanine [76]. 3.3.4.1 Accumulation of polycyclic aromatic hydrocarbons in plants PAHs can accumulate in plant tissues and can easily enter in food chain, and hence affect living organisms due to their adverse properties. Phenanthrene and chrysene concentration were present in higher amounts in roots and above-ground tissue. LMW-PAHs are in general more dominant as compared to HMW PAHs due to their high solubility and volatility. Due to their high uptake and accumulation, LMW-PAHs are abundant in tissues of ryegrass, Arabidopsis thaliana and mangroves. Shoots mostly possess two- or three-ring PAHs [73]. Yakovleva et al. [75] showed plant biomass decreased four to five times in areas contaminated with naphthalene, phenanthrene and fluorene. Highest PAH content was found in grasses Dudleya caespitose, Festuca ovina and lichen Cladonia gracilis. Due to strong root system and thin surface tissues, herbaceous plants have tendency to absorb PAHs from roots. Air is the main route of PAH uptake by bushes and mosses. Shrubs uptake and accumulate. Absorption of PAHs by plants on the basis of structure was observed in the following order: two- three ring . four ring . six ring . five ring [80].

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Accumulation of PAHs in vegetation depends on its type, property of accumulating surface and environmental conditions. Jouraeva et al. [81] studied the difference in accumulation of PAHs on the leaves of two deciduous plants (linden and pears); linden leaves have higher capacity of PAHs accumulation than pear leaves. Not much detail is available on genomic impacts on accumulation of PAHs in plants, but phenanthrene exposure reduced expression of expansion (EXP8) that have role in cell enlargement and cell wall loosening and it also induced pathogenesis related protein (PR1) that has role in defence mechanism [82]. 3.3.4.2 Effect on plant growth PAHs concentration and plant tolerance level can influence plant biomass as a result of the impact on seed germination, growth and plant establishment [83]. Toxicity of PAHs depends on plant species, concentration of PAHs and soil properties [84]. Afegbua and Batty [83] reported that PAH treatment can either stimulate or inhibit plant biomass yield. Cheema et al. [85] reported that pyrene (199 mg/kg) and phenanthrene (200 mg/kg) decreased Medicago sativa biomass by 35%. Jeelani et al. [86] reported that biomass yield improved in Acorus calamus when soil was polluted with a concentration of 50 100 mg/kg phenanthrene and 25 50 mg/kg pyrene concentration. PAHs at higher concentration (PAH $ 10 mg/kg) have inhibitory effect on plant [87]. Benzo[a]pyrene at # 10 mg/kg increased biomass yield in Tagetes patula [88]. PAHs at 100 mg/kg significantly reduced root length in bean, sunflower, wheat and tomato. Similarly, stem length was inhibited in bean, oat, wheat and tomato [84]. Complete inhibition of seed germination of oat, millet and lettuce was observed in contaminated soil [89]. Soil contamination with fuel oil inhibited seed germination of sunflower, wheat, maize, barley, lettuce, clover and bean [90]. With an increase in phenanthrene concentration from 0.05 to 0.2 mg/mL, root and shoot length decreases. Pyrene and phenanthrene at concentration of 400 mg/kg decreased rice biomass to 25% [87,91]. 3.3.4.3 Effect on photosynthetic activity Effect of PAHs on photosynthesis is independent of their aromaticity [92]. PAHs inhibit photosynthetic activity in plants and algae, and reduce chlorophyll and carotenoid content [93]. Anthracene reported to inhibit electron trapping and transfer PS II PS I cooperation imbalance, rearrange PS II core, degrade PS II proteins and decrease active PS II reaction centre numbers that lead to decreased photosynthetic activity [79]. Naphthalene, anthracene and pyrene decrease chlorophyll a and chlorophyll b content in Arabidopsis thaliana [92]. At higher pyrene concentrations ( . 3 mg/L), chlorophyl a content and genes encoded for PS II proteins were affected, especially D1 protein and psbO proteins [94]. Hydrophobic PAHs get accumulate in thylakoid membrane, affect its integrity, induce conformational change in their structure, inhibit photophosphorylation, and disrupt photosynthesis at both acceptor and donor site of PS II [95,96]. Fluoranthene exposure significantly reduces chlorophyll a, chlorophyll b, total chlorophyll (a 1 b) and carotenoid content in cherry tomato plants, and decreases stomatal conductance and efficiency of PS II in dark [97]. Effect of phenanthrene on wheat seedlings and chlorophyll a content was observed to be reduced to 92.5%, 81.31% and 52.33% at

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0.05 mg/mL, 0.10 mg/mL and 0.20 mg/mL, respectively [74]. PAHs (phenanthrene and pyrene) at concentration of 400 mg/kg led to 29% decrease in chlorophyll content in rice seedling [87].

3.4 Bioremediation of polycyclic aromatic hydrocarbons Bioremediation is a biological process in which pollutants are eliminated or converted into less toxic molecules by microorganisms. Microorganisms are typically involved in the conversion of pollutants/toxic contaminants into less toxic pollutants [98]. Some of the strategies to achieve microbial bioremediation are biosorption, biostimulation, phytoremediation, and bioaugmentation [99,100]. Among all the currently available strategies, biodegradation by diverse microbes is the most promising means of bioremediation as microbes have continuously been evolved and developed their ability to adapt in an unfavourable environmental condition over the years [101]. Various microbes have been identified that are capable of degrading PAHs. Metabolic pathways followed by microbes to degrade pollutants especially PAHs in the environment matrices have been studied in detail [15,31,50,102,103]. Further knowledge is needed to improve our understanding of these processes in different habitats. One reason for this is increase in anthropogenic activities that leads to generation of more stable PAHs in surroundings. PAH degradation by microbes follows either aerobic or anaerobic mode. During aerobic mode of PAH degradation, monooxygenase and dioxygenases hydroxylate one of the PAHs rings in the structure by adding oxygen molecule that acts as a final electron acceptor and mediates ring cleavage of aromatic compounds [104]. However, during anaerobic mode of biodegradation, microbes follow an entirely different pathway to reduce the aromatic ring structure of PAHs. Sulphate or ferric and nitrate ions serve as final electron acceptors [31,105]. Monooxygenase or dioxygenase mediated metabolism of PAHs is favourable. First step of the degradation pathways is the production of cis-dihydrodiols followed by formation of catechol derivatives via dehydrogenases enzymes. Further, 1,2dioxygenase and 2,3-dioxygenase cleave catechol via ortho or meta cleavage pathway, respectively. Intradiol cleavage forms cis, cis-muconic acid and extra-diol cleavage forms muconic semialdehyde [31,50] that may enter into TCA cycle [106,107]. Microbes either form biofilm or produce biosurfactants that aid in the utilization and consumption of PAHs [108,109]. Bacterial biosurfactants lower the interfacial tension or surface tension of an interface making pollutant more accessible to microorganisms [110]. Bacillus circulans has been shown to produce biosurfactant as a strategy to degrade PAHs [111]. Acinetobacter radioresistens emulsified phenanthrene, benzo(a)pyrene, benzene, pyrene, chysene, etc [111,112]. Naphthalene is frequently used as a model chemical to study potential of microbes to breakdown PAHs [113]. Knowledge on microbial naphthalene degradation has been used to understand and anticipate processes in the breakdown of other PAHs with three or more rings. Alcaligenes [114], Burkholderia [115], Mycobacterium [116], Polaromonas [117], Pseudomonas [118], Ralstonia [119], Rhodococcus [120], Sphingomonas [121] and Streptomyces [122] are some bacteria that uses naphthalene for their growth [102]. Microbial use of

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phenanthrene as carbon and energy source by various bacteria has been reported [123]. Phenanthrene, a three aromatic ring angular structure, contains K-region and Bay-region that forms epoxides upon breakdown. These epoxides are known to be potential carcinogen; therefore phenanthrene is also studied as model substrate to understand the catabolism of other HMW PAHs [50]. Strains of Burkholderia, Pasteurella, Mycobacterium and Tenotrophomonas have been shown to biodegrade fluoranthene, a four aromatic ring compound [50]. Bacillus megaterium YB3 [124], B. cereus [125], Burkholderia cepacia [126], Cycloclasticus sp. P1 [127], Pseudomonas fluorescens [128], P. stutzeri [108], strain of Sphingomonas [104], Sphingomonas paucimobilis and Stenotrophomonas maltophilia [129] are known to biodegrade pyrene. PAH degradation by cyanobacteria (blue-green algae) [130] and freshwater green algae (Selenastrum capricornutum) were also reported [131]. Combination of algal bacteria was also reported to biodegrade PAHs [132].

3.4.1 Bioaugmentation In order to aid the native bacteria in their biodegradative activities, this strategy entails introducing microorganisms with the ability for biodegradation into the contaminated environment. An efficient bacterium or microbial consortia having the ability to degrade PAHs are added to contaminated sites as part of the bioaugmentation technique [133]. Bacillus cereus, B. sphaericus, B. fusiformis, B. pumilus, A. junii and Pseudomonas sp. were able to decompose 72.7% of the light TPH (total petroleum hydrocarbons) and 75.2% of the heavy TPH [134]. Teng et al. [135] found 23.2% decline in total soil PAH concentrations after 28 days. They also observed that degradation for 3 ring (35.1%), 4 ring (20.7%), and 5 ( 1 6)-ring PAHs was 24.3%. Bioaugmentation is associated with certain limitations as some strains of microorganisms do not thrive and biodegrade xenobiotics in comparison to native microbes [136]. Bioaugmentation has not yet been widely embraced, particularly the use of genetically modified microbes because of concerns that their introduction into contaminated soil could change the ecology of the area and endanger human health if they continue to exist after the contamination has been removed [137].

3.4.2 Biostimulation Biostimulation refers to the increased activity of native bacteria that are capable of decomposing contaminants in the soil environments. In order to improve the activity of native microorganisms, organic or inorganic nutrients were supplemented to the contaminated site. Commercial oleophilic fertilizers with nitrogen and phosphate were added to polluted soil, which led to the enhancement of indigenous microbes that break down hydrocarbons [138]. A loss of 77% 95% and 80% of total alkanes and PAHs respectively from the oil-contaminated soil in 180 days has been reported. Another study found that the use of manure as fertilizer and surfactants has positive effect on biodegradation [139]. The biodegradation of organic materials is reported to be lower in high nutrient concentrations [140], and numerous studies have highlighted the harmful effects of increased NPK amount on aromatic compounds biodegradation [141 143]. Further, there is a need to explore more microbe for their potential to remediate these highly toxic pollutants.

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Acknowledgement The authors acknowledge GGS Indraprastha University for providing research facilities and academic environment to do this kind of work. Kamal Krishan Aggarwal acknowledges FRGS grant to work in the related areas which has encouraged to write this chapter. Shanky Jindal acknowledges IPRF of GGSIPU.

References [1] S.K. Patel, A. Sharma, G.S. Singh, Traditional agricultural practices in India: an approach for environmental sustainability and food security, Energy Ecol. Environ. 5 (2020) 253 271. [2] H.I. Abdel-Shafy, M.S. Mansour, A review on polycyclic aromatic hydrocarbons: source, environmental impact, effect on human health and remediation, Egypt. J. Pet. 25 (1) (2016) 107 123. [3] S.Y. Lee, S.S. Sekhon, Y.H. Ban, J.Y. Ahn, J.H. Ko, L. Lee, et al., Proteomic analysis of polycyclic aromatic hydrocarbons (PAHs) degradation and detoxification in Sphingobium chungbukense DJ77, J. Microbiology Biotechnol. 26 (11) (2016) 1943 1950. [4] P. Srivastava, T.R. Sreekrishnan, A.K. Nema, Polyaromatic hydrocarbons: review of a global environmental issue, J. Hazardous, Toxic, Radioactive Waste 22 (3) (2018) 04018004. [5] H. Zheng, X. Xing, T. Hu, Y. Zhang, J. Zhang, G. Zhu, et al., Biomass burning contributed most to the human cancer risk exposed to the soil-bound PAHs from Chengdu Economic Region, western China, Ecotoxicol. Environ. saf. 159 (2018) 63 70. [6] A. Mojiri, J.L. Zhou, A. Ohashi, N. Ozaki, T. Kindaichi, Comprehensive review of polycyclic aromatic hydrocarbons in water sources, their effects and treatments, Sci. Total Environ. 696 (2019) 133971. [7] U. Okere, K.T. Semple, Biodegradation of PAHs in ‘pristine’soils from different climatic regions, J. Bioremed. Biodegrad. 1 (2) (2012) 1 11.2. [8] S. Kim, J. Chen, T. Cheng, A. Gindulyte, J. He, S. He, et al., PubChem in 2021: new data content and improved web interfaces, Nucleic Acids Res. 49 (D1) (2019) D1388 D1395. [9] A. Mahvi, G. Mardani, P. Ghasemi-Dehkordi, J. Saffari-Chaleshtori, M. Hashemzadeh-Chaleshtori, M. Allahbakhshian-Farsani, et al., Effects of phenanthrene and pyrene on cytogenetic stability of human dermal fibroblasts using alkaline comet assay technique, Proc. Natl. Acad. Sci., India Sect. B: Biol. Sci. 85 (4) (2015) 1055 1063. [10] Al Reshetyuk, E.I. Talakina, P.A. En’yakova, Toxicological evaluation of acenaphthene and acenaphthylene, Gig. Tr. Prof. Zabol. 14 (1970) 46 47. [11] H. Sakakibara, T. Ohura, T. Kido, N. Yamanaka, N. Tanimura, K. Shimoi, et al., Organ-specific distribution of 7-chlorinated benz [a] anthracene and regulation of selected cytochrome P450 genes in rats, J. Toxicological Sci. 38 (1) (2013) 137 143. [12] K. Ravindra, R. Sokhi, R. Van Grieken, Atmospheric polycyclic aromatic hydrocarbons: source attribution, emission factors and regulation, Atmos. Environ. 42 (13) (2008) 2895 2921. [13] N.T. Edwards, Polycyclic aromatic hydrocarbons (PAH’s) in the terrestrial environment—a review, J. Environ. Qual. 12 (4) (1983) 427 441. [14] A.K. Haritash, C.P. Kaushik, Biodegradation aspects of polycyclic aromatic hydrocarbons (PAHs): a review, J. Hazard. Mater. 169 (1 3) (2009) 1 15. [15] R.H. Peng, A.S. Xiong, Y. Xue, X.Y. Fu, F. Gao, W. Zhao, et al., Microbial biodegradation of polyaromatic hydrocarbons, FEMS Microbiology Rev. 32 (6) (2008) 927 955. [16] D.S. Parker, F. Zhang, Y.S. Kim, R.I. Kaiser, A. Landera, V.V. Kislov, et al., Low temperature formation of naphthalene and its role in the synthesis of PAHs (polycyclic aromatic hydrocarbons) in the interstellar medium, Proc. Natl. Acad. Sci. 109 (1) (2012) 53 58. [17] J.S. Latimer, J. Zheng, Fate of PAHs in the marine environment, PAHs: Ecotoxicolog. Perspect. 9 (2003). [18] C.R. Marris, S.N. Kompella, M.R. Miller, J.P. Incardona, F. Brette, J.C. Hancox, et al., Polyaromatic hydrocarbons in pollution: a heart-breaking matter, J. Physiol. 598 (2) (2020) 227 247. [19] E.J. Calabrese, R.B. Blain, Hormesis and plant biology, Environ. Pollut. 157 (1) (2009) 42 48. [20] M.J. Suess, The environmental load and cycle of polycyclic aromatic hydrocarbons, Sci. Total Environ. 6 (3) (1976) 239 250.

Green Chemistry Approaches to Environmental Sustainability

60

3. Toxicity of polyaromatic hydrocarbons and their biodegradation in the environment

[21] B. Armstrong, E. Hutchinson, J. Unwin, T. Fletcher, Lung cancer risk after exposure to polycyclic aromatic hydrocarbons: a review and meta-analysis, Environ. Health Perspect. 112 (9) (2004) 970 978. [22] H. Yu, Environmental carcinogenic polycyclic aromatic hydrocarbons: photochemistry and phototoxicity, J. Environ. Sci. Health Part C 20 (2) (2002) 149 183. [23] A. Tarantini, A. Maitre, E. Lefebvre, M. Marques, C. Marie, J.L. Ravanat, et al., Relative contribution of DNA strand breaks and DNA adducts to the genotoxicity of benzo[a]pyrene as a pure compound and in complex mixtures, Mutat. Res./Fundam. Mol. Mechan. Mutag. 671 (1 2) (2009) 67 75. [24] A.L. Bolden, J.R. Rochester, K. Schultz, C.F. Kwiatkowski, Polycyclic aromatic hydrocarbons and female reproductive health: a scoping review, Reprod. Toxicol. 73 (2017) 61 74. [25] T.L. Smith, S.T. Merry, D.L. Harris, J.J. Ford, J. Ike, A.E. Archibong, A. Ramesh, Species-specific testicular and hepatic microsomal metabolism of benzo (a) pyrene, an ubiquitous toxicant and endocrine disruptor, Toxicology In Vitro 21 (4) (2007) 753 758. [26] T. Rengarajan, P. Rajendran, N. Nandakumar, B. Lokeshkumar, P. Rajendran, I. Nishigaki, Exposure to polycyclic aromatic hydrocarbons with special focus on cancer, Asian Pac. J. Trop. Biomed. 5 (3) (2015) 182 189. [27] F. Perera, D. Tang, R. Whyatt, S.A. Lederman, W. Jedrychowski, DNA damage from polycyclic aromatic hydrocarbons measured by benzo [a] pyrene-DNA adducts in mothers and newborns from Northern Manhattan, the World Trade Center Area, Poland, and China, Cancer Epidemiol. Prev. Biomarkers 14 (3) (2005) 709 714. [28] Ł. Ławniczak, M. Wo´zniak-Karczewska, A.P. Loibner, H.J. Heipieper, Ł. Chrzanowski, Microbial degradation of hydrocarbons—basic principles for bioremediation: a review, Molecules 25 (4) (2020) 856. [29] M.P. Shah, Environmental bioremediation: a low cost nature’s natural biotechnology for environmental clean-up, J. Pet. Environ. Biotechnol. 5 (4) (2014) 1. [30] C. Lu, Y. Hong, J. Liu, Y. Gao, Z. Ma, B. Yang, et al., A PAH-degrading bacterial community enriched with contaminated agricultural soil and its utility for microbial bioremediation, Environ. Pollut. 251 (2019) 773 782. [31] S. Mallick, J. Chakraborty, T.K. Dutta, Role of oxygenases in guiding diverse metabolic pathways in the bacterial degradation of low-molecular-weight polycyclic aromatic hydrocarbons: a review, Crit. Rev. Microbiol. 37 (1) (2011) 64 90. [32] X. Yang, E. Li, F. Liu, M. Xu, Interactions of PAH-degradation and nitrate-/sulfate-reducing assemblages in anaerobic sediment microbial community, J. Hazard. Mater. 388 (2020) 122068. [33] S. Shankar, C. Kansrajh, M.G. Dinesh, R.S. Satyan, S. Kiruthika, A. Tharanipriya, Application of indigenous microbial consortia in bioremediation of oil-contaminated soils, Int. J. Environ. Sci. Technol. 11 (2) (2014) 367 376. [34] X. Li, L. Zhao, M. Adam, Biodegradation of marine crude oil pollution using a salt-tolerant bacterial consortium isolated from Bohai Bay, China, Mar. Pollut. Bull. 105 (1) (2016) 43 50. [35] M. Bouchez, D. Blanchet, V. Bardin, F. Haeseler, J.P. Vandecasteele, Efficiency of defined strains and of soil consortia in the biodegradation of polycyclic aromatic hydrocarbon (PAH) mixtures, Biodegradation 10 (6) (1999) 429 435. [36] J. Arey, R. Atkinson, Photochemical reactions of PAHs in the atmosphere, PAHs: An Ecotoxicological Perspective, Wiley, 2003, pp. 47 63. [37] D.M. Di Toro, J.A. McGrath, D.J. Hansen, Technical basis for narcotic chemicals and polycyclic aromatic hydrocarbon criteria. I. Water and tissue, Environ. Toxicol. Chem. Int. J. 19 (8) (2000) 1951 1970. [38] P. Di Filippo, D. Pomata, C. Riccardi, F. Buiarelli, V. Gallo, Oxygenated polycyclic aromatic hydrocarbons in size-segregated urban aerosol, J. Aerosol Sci. 87 (2015) 126 134. [39] C.Y. Kuo, P.S. Chien, W.C. Kuo, C.T. Wei, J.Y. Rau, Comparison of polycyclic aromatic hydrocarbon emissions on gasoline-and diesel-dominated routes, Environ. Monit. Assess. 185 (2013) 5749 5761. [40] T. Kameda, Atmospheric chemistry of polycyclic aromatic hydrocarbons and related compounds, J. Health Sci. 57 (6) (2011) 504 511. [41] I.C. Lai, C.L. Lee, K.Y. Zeng, H.C. Huang, Seasonal variation of atmospheric polycyclic aromatic hydrocarbons along the Kaohsiung coast, J. Environ. Manag. 92 (8) (2011) 2029 2037. [42] Y. Zhang, S. Tao, Global atmospheric emission inventory of polycyclic aromatic hydrocarbons (PAHs) for 2004, Atmos. Environ. 43 (4) (2009) 812 819.

Green Chemistry Approaches to Environmental Sustainability

References

61

[43] A. Masih, A. Taneja, Polycyclic aromatic hydrocarbons (PAHs) concentrations and related carcinogenic potencies in soil at a semi-arid region of India, Chemosphere 65 (3) (2006) 449 456. [44] R.P. Schwarzenbach, P.M. Gschwend, D.M. Imboden, Organic liquid water partitioning, Environmental Organic Chemistry, Wiley, Hoboken, New Jersey, 2003, pp. 213 244. [45] G.M. Tehrani, R.O.S.L.I. Hashim, A.H. Sulaiman, S.T. Sany, A. Salleh, R.K. Jazani, R.F. Barandoust, Distribution of total petroleum hydrocarbons and polycyclic aromatic hydrocarbons in Musa Bay sediments (Northwest of the Persian Gulf), Environ. Prot. Eng. 39 (1) (2013) 115 128. [46] C.D. Dong, C.F. Chen, C.W. Chen, Determination of polycyclic aromatic hydrocarbons in industrial harbor sediments by GC-MS, Int. J. Environ. Res. Public Health 9 (6) (2012) 2175 2188. [47] K.H. Kim, S.A. Jahan, E. Kabir, R.J. Brown, A review of airborne polycyclic aromatic hydrocarbons (PAHs) and their human health effects, Environ. Int. 60 (2013) 71 80. [48] A. Paris, J. Ledauphin, P. Poinot, J.L. Gaillard, Polycyclic aromatic hydrocarbons in fruits and vegetables: Origin, analysis, and occurrence, Environ. Pollut. 234 (2018) 96 106. [49] R. Mohanraj, S. Dhanakumar, G. Solaraj, Polycyclic aromatic hydrocarbons bound to PM 2.5 in urban Coimbatore, India with emphasis on source apportionment, Sci. world J. 2012 (2012). [50] N. Premnath, K. Mohanrasu, R.G.R. Rao, G.H. Dinesh, G.S. Prakash, V. Ananthi, et al., A crucial review on polycyclic aromatic Hydrocarbons-Environmental occurrence and strategies for microbial degradation, Chemosphere 280 (2021) 130608. [51] A.U.R.E.L.I.A. Coroian, M. Vioara, C.C. Ovidiu, C. Raducu, D. Cocan, L.U.I.S.A. Andronie, et al., The level of polycyclic aromatic hydrocarbons (PAHs) from pork meat depending on the heat treatment applied, Romanian Biotechnological Lett. 25 (3) (2020) 1601 1606. [52] A. Mantovani, D. Ferrari, C. Frazzoli, Sustainability, security and safety in the feed-to-fish chain: focus on toxic contamination, Int. J. Nutr. Food Sci. 4 (2-2) (2015) 6 24. [53] P. Boffetta, N. Jourenkova, P. Gustavsson, Cancer risk from occupational and environmental exposure to polycyclic aromatic hydrocarbons, Cancer Causes Control. 8 (3) (1997) 444 472. [54] F. Kamangar, M.M. Schantz, C.C. Abnet, R.B. Fagundes, S.M. Dawsey, High levels of carcinogenic polycyclic aromatic hydrocarbons in mate drinks, Cancer Epidemiol. Prev. Biomarkers 17 (5) (2008) 1262 1268. [55] P. Kristensen, E. Eilertsen, E. Einarsdo´ttir, A. Haugen, V. Skaug, S. Ovrebø, Fertility in mice after prenatal exposure to benzo [a] pyrene and inorganic lead, Environ. Health Perspect. 103 (6) (1995) 588 590. [56] A. Ren, X. Qiu, L. Jin, J. Ma, Z. Li, L. Zhang, et al., Association of selected persistent organic pollutants in the placenta with the risk of neural tube defects, Proc. Natl. Acad. Sci. 108 (31) (2011) 12770 12775. [57] Y. Yuan, L. Jin, L. Wang, Z. Li, L. Zhang, H. Zhu, et al., Levels of PAH DNA adducts in placental tissue and the risk of fetal neural tube defects in a Chinese population, Reprod. Toxicol. 37 (2013) 70 75. [58] W. Wilcke, W. Amelung, C. Martius, M.V. Garcia, W. Zech, Biological sources of polycyclic aromatic hydrocarbons (PAHs) in the Amazonian rain forest, J. Plant. Nutr. Soil. Sci. 163 (1) (2000) 27 30. [59] L. Huang, Z. Xi, C. Wang, Y. Zhang, Z. Yang, S. Zhang, et al., Phenanthrene exposure induces cardiac hypertrophy via reducing miR-133a expression by DNA methylation, Sci. Rep. 6 (1) (2016) 1 15. [60] T.K. Collier, B.F. Anulacion, M.R. Arkoosh, J.P. Dietrich, J.P. Incardona, L.L. Johnson, et al., Effects on fish of polycyclic aromatic hydrocarbons (PAHs) and naphthenic acid exposures, Fish. Physiol. 33 (2013) 195 255. [61] M. Honda, N. Suzuki, Toxicities of polycyclic aromatic hydrocarbons for aquatic animals, Int. J. Environ. Res. Public. Health 17 (4) (2020) 1363. [62] A. Ball, A. Truskewycz, Polyaromatic hydrocarbon exposure: an ecological impact ambiguity, Environ. Sci. Pollut. Res. 20 (7) (2013) 4311 4326. [63] A.U.R.E.L.I.A. Coroian, M. Vioara, C.C. Ovidiu, C. Raducu, D. Cocan, L.U.I.S.A. Andronie, Z. Marchi¸s, The level of polycyclic aromatic hydrocarbons (PAHs) from pork meat depending on the heat treatment applied, Rom. Biotechnol. Lett. 25 (3) (2020) 1601 1606. [64] M. Meurillon, J. Ratel, E. Engel, How to secure the meat chain against toxicants? Innovative Food Sci. Emerg. Technol. 46 (2018) 74 82. [65] R.A. Khan, Effects of polycyclic aromatic hydrocarbons on sexual maturity of Atlantic cod, Gadus morhua, following chronic exposure, Environ. Pollut. 2 (1) (2013) 1 10. [66] S.M. Bugel, L.A. White, K.R. Cooper, Impaired reproductive health of killifish (Fundulus heteroclitus) inhabiting Newark Bay, NJ, a chronically contaminated estuary, Aquat. Toxicol. 96 (3) (2010) 182 193.

Green Chemistry Approaches to Environmental Sustainability

62

3. Toxicity of polyaromatic hydrocarbons and their biodegradation in the environment

[67] J.P. Meador, F.C. Sommers, G.M. Ylitalo, C.A. Sloan, Altered growth and related physiological responses in juvenile Chinook salmon (Oncorhynchus tshawytscha) from dietary exposure to polycyclic aromatic hydrocarbons (PAHs), Can. J. Fish. Aquat. Sci. 63 (10) (2006) 2364 2376. [68] B.D. Hersikorn, J.E. Smits, Compromised metamorphosis and thyroid hormone changes in wood frogs (Lithobates sylvaticus) raised on reclaimed wetlands on the Athabasca oil sands, Environ. Pollut. 159 (2) (2011) 596 601. [69] D.E. Jones, G. Magnin-Bissel, S.D. Holladay, Detection of polycyclic aromatic hydrocarbons in the shed skins of corn snakes (Elaphe guttata), Ecotoxicol. Environ. Saf. 72 (7) (2009) 2033 2035. [70] C.A. Rice, M.S. Myers, M.L. Willis, B.L. French, E. Casillas, From sediment bioassay to fish biomarker—connecting the dots using simple trophic relationships, Mar. Environ. Res. 50 (1 5) (2000) 527 533. [71] H. Connelly, J.C. Means, Immunomodulatory effects of dietary exposure to selected polycyclic aromatic hydrocarbons in the bluegill (Lepomis macrochirus), Int. J. Toxicol. 29 (5) (2010) 532 545. [72] A. Tintos, M. Gesto, J.M. Mı´guez, J.L. Soengas, Naphthalene treatment alters liver intermediary metabolism and levels of steroid hormones in plasma of rainbow trout (Oncorhynchus mykiss), Ecotoxicol. Environ. Saf. 66 (2) (2007) 139 147. [73] S. Sushkova, T. Minkina, S. Tarigholizadeh, E. Antonenko, E. Konstantinova, C. Gu¨lser, et al., PAHs accumulation in soil-plant system of Phragmites australis Cav. in soil under long-term chemical contamination, Eurasian J. Soil Sci. 9 (3) (2020) 242 253. [74] H. Wei, S. Song, H. Tian, T. Liu, Effects of phenanthrene on seed germination and some physiological activities of wheat seedling, Comptes Rendus Biologies 337 (2) (2014) 95 100. [75] E.V. Yakovleva, D.N. Gabov, V.A. Beznosikov, B.M. Kondratenok, Y.A. Dubrovskiy, Accumulation of PAHs in tundra plants and soils under the influence of coal mining, Polycycl. Aromatic Compd. 37 (2 3) (2017) 203 218. [76] M. Berteigne, C. Rose, J. Ge´rard, P. Dizengremel, Effects of polyaromatic hydrocarbons on the forest ecosystem and woody plants, Annales des. Sci. Forestie`res 46 (1989) 561s 564s. [77] J. Fismes, C. Perrin-Ganier, P. Empereur-Bissonnet, J.L. Morel, Soil-to-root transfer and translocation of polycyclic aromatic hydrocarbons by vegetables grown on industrial contaminated soils, J. Environ. Qual. 31 (5) (2002) 1649 1656. [78] A.V. Lankin, V.D. Kreslavski, A.Y. Khudyakova, S.K. Zharmukhamedov, S.I. Allakhverdiev, Effect of naphthalene on photosystem 2 photochemical activity of pea plants, Biochem. (Mosc.) 79 (11) (2014) 1216 1225. [79] A. Aksmann, Z. Tukaj, Intact anthracene inhibits photosynthesis in algal cells: a fluorescence induction study on Chlamydomonas reinhardtii cw92 strain, Chemosphere 74 (1) (2008) 26 32. [80] A. Gałuszka, Distribution patterns of PAHs and trace elements in mosses Hylocomium splendens (Hedw.) BSG and Pleurozium schreberi (Brid.) Mitt. from different forest communities: a case study, south-central Poland, Chemosphere 67 (7) (2007) 1415 1422. [81] V.A. Jouraeva, D.L. Johnson, J.P. Hassett, D.J. Nowak, Differences in accumulation of PAHs and metals on the leaves of Tilia 3 euchlora and Pyrus calleryana, Environ. Pollut. 120 (2) (2002) 331 338. [82] M. Alkio, T.M. Tabuchi, X. Wang, A. Colon-Carmona, Stress responses to polycyclic aromatic hydrocarbons in Arabidopsis include growth inhibition and hypersensitive response-like symptoms, J. Exp. Botany 56 (421) (2005) 2983 2994. [83] S.L. Afegbua, L.C. Batty, Effect of single and mixed polycyclic aromatic hydrocarbon contamination on plant biomass yield and PAH dissipation during phytoremediation, Environ. Sci. Pollut. Res. 25 (19) (2018) 18596 18603. [84] B. Maliszewska-Kordybach, B. Smreczak, Ecotoxicological activity of soils polluted with polycyclic aromatic hydrocarbons (PAHs)-effect on plants, Environ. Technol. 21 (10) (2000) 1099 1110. [85] S.A. Cheema, M. Imran Khan, C. Shen, X. Tang, M. Farooq, L. Chen, et al., Degradation of phenanthrene and pyrene in spiked soils by single and combined plants cultivation, J. Hazard. Mater. 177 (2010) 384 389. [86] N. Jeelani, W. Yang, L. Xu, Y. Qiao, S. An, X. Leng, Phytoremediation potential of Acorus calamus in soils co-contaminated with cadmium and polycyclic aromatic hydrocarbons, Sci. Rep. 7 (1) (2017) 1 9. [87] J.H. Li, Y. Gao, S.C. Wu, K.C. Cheung, X.R. Wang, M.H. Wong, Physiological and biochemical responses of rice (Oryza sativa L.) to phenanthrene and pyrene, Int. J. Phytoremediat. 10 (2) (2008) 106 118. [88] Y. Sun, Q. Zhou, Y. Xu, L. Wang, X. Liang, Phytoremediation for cocontaminated soils of benzo[a]pyrene (B[a]P) and heavy metals using ornamental plant Tagetes patula, J. Hazard. Mater. 186 (2) (2011) 2075 2082.

Green Chemistry Approaches to Environmental Sustainability

References

63

[89] F. Baud-Grasset, S. Baud-Grasset, S.I. Safferman, Evaluation of the bioremediation of a contaminated soil with phytotoxicity tests, Chemosphere 26 (7) (1993) 1365 1374. [90] C.H. Chaineau, J.L. Morel, J. Oudot, Phytotoxicity and plant uptake of fuel oil hydrocarbons, J. Environ. Qual. 26 (6) (1997) 1478 1483. [91] X. Mei, D.H. Lin, Y. Xu, Y.Y. Wu, Y.Y. Tu, Effects of phenanthrene on chemical composition and enzyme activity in fresh tea leaves, Food Chem. 115 (2) (2009) 569 573. [92] A. Jajoo, N.R. Mekala, R.S. Tomar, M. Grieco, M. Tikkanen, E.M. Aro, Inhibitory effects of polycyclic aromatic hydrocarbons (PAHs) on photosynthetic performance are not related to their aromaticity, J. Photochem. Photobiol. B: Biol. 137 (2014) 151 155. [93] A.S. Petsas, M.C. Vagi, Effects on the photosynthetic activity of algae after exposure to various organic and inorganic pollutants, Chlorophyll (2017) 37. [94] J. Shao, G. Yu, Z. Wu, X. Peng, R. Li, Responses of Synechocystis sp. PCC 6803 (cyanobacterium) photosystem II to pyrene stress, J. Environ. Sci. 22 (7) (2010) 1091 1095. [95] A. Aksmann, T. Shutova, G. Samuelsson, Z. Tukaj, The mechanism of anthracene interaction with photosynthetic apparatus: a study using intact cells, thylakoid membranes and PS II complexes isolated from Chlamydomonas reinhardtii, Aquat. Toxicol. 104 (3 4) (2011) 205 210. [96] J.H. McCann, K.R. Solomon, The effect of creosote on membrane ion leakage in Myriophyllum spicatum L, Aquat. Toxicol. 50 (3) (2000) 275 284. [97] I. Oguntimehin, F. Eissa, H. Sakugawa, Negative effects of fluoranthene on the ecophysiology of tomato plants (Lycopersicon esculentum Mill): Fluoranthene mists negatively affected tomato plants, Chemosphere 78 (7) (2010) 877 884. [98] T. Langenbach, Persistence and bioaccumulation of persistent organic pollutants (POPs), Applied bioremediation-active and passive approaches 10 (2013) 56418. [99] S. Sharma, Bioremediation: features, strategies and applications, Asian J. Pharm. Life Sci. 2231 (2012) 4423. [100] Y. Zheng, C. Xiao, R. Chi, Remediation of soil cadmium pollution by biomineralization using microbialinduced precipitation: a review, World J. Microbiol. Biotechnol. 37 (2021) 1 15. [101] D. Ghosal, S. Ghosh, T.K. Dutta, Y. Ahn, Current state of knowledge in microbial degradation of polycyclic aromatic hydrocarbons (PAHs): a review, Front. Microbiology 7 (2016) 1369. [102] J.S. Seo, Y.S. Keum, Q.X. Li, Bacterial degradation of aromatic compounds, Int. J. Environ. Res. Public Health 6 (1) (2009) 278 309. [103] M. Govarthanan, A.Y. Khalifa, S. Kamala-Kannan, P. Srinivasan, T. Selvankumar, K. Selvam, W. Kim, Significance of allochthonous brackish water Halomonas sp. on biodegradation of low and high molecular weight polycyclic aromatic hydrocarbons, Chemosphere 243 (2020) 125389. [104] M. Baboshin, V. Akimov, B. Baskunov, T.L. Born, S.U. Khan, L. Golovleva, Conversion of polycyclic aromatic hydrocarbons by Sphingomonas sp. VKM B-2434, Biodegradation 19 (4) (2008) 567 576. [105] J. Foght, Anaerobic biodegradation of aromatic hydrocarbons: pathways and prospects, Microb. Physiol. 15 (2 3) (2008) 93 120. [106] C.E. Cerniglia, The environment, microbes and bioremediation: microbial activities modulated by the environment, Biodegradation 3 (1992) 351 357. [107] W.C. Evans, H.N. Fernley, E. Griffiths, Oxidative metabolism of phenanthrene and anthracene by soil pseudomonads. The ring-fission mechanism, Biochem. J. 95 (3) (1965) 819. [108] P. Singh, B.N. Tiwary, Optimization of conditions for polycyclic aromatic hydrocarbons (PAHs) degradation by Pseudomonas stutzeri P2 isolated from Chirimiri coal mines, Biocatalysis Agric. Biotechnol. 10 (2017) 20 29. [109] L. Zhang, P. Li, Z. Gong, X. Li, Photocatalytic degradation of polycyclic aromatic hydrocarbons on soil surfaces using TiO2 under UV light, J. Hazard. Mater. 158 (2 3) (2008) 478 484. [110] K. Patowary, R. Patowary, M.C. Kalita, S. Deka, Characterization of biosurfactant produced during degradation of hydrocarbons using crude oil as sole source of carbon, Front. Microbiol. 8 (2017) 279. [111] P. Das, S. Mukherjee, R. Sen, Antimicrobial potential of a lipopeptide biosurfactant derived from a marine Bacillus circulans, J. Appl. Microbiol. 104 (6) (2008) 1675 1684. [112] A. Toren, E. Orr, Y. Paitan, E.Z. Ron, E. Rosenberg, The active component of the bioemulsifier alasan from Acinetobacter radioresistens KA53 is an OmpA-like protein, J. Bacteriol. 184 (1) (2002) 165 170.

Green Chemistry Approaches to Environmental Sustainability

64

3. Toxicity of polyaromatic hydrocarbons and their biodegradation in the environment

[113] L.A. Kulakov, S. Chen, C.C. Allen, M.J. Larkin, Web-type evolution of Rhodococcus gene clusters associated with utilization of naphthalene, Appl. Environ. Microbiology 71 (4) (2005) 1754 1764. [114] W.F. Guerin, S.A. Boyd, Maintenance and induction of naphthalene degradation activity in Pseudomonas putida and an Alcaligenes sp. under different culture conditions, Appl. Environ. Microbiology 61 (11) (1995) 4061 4068. [115] A.E. Filonov, I.F. Puntus, A.V. Karpov, I.A. Kosheleva, L.I. Akhmetov, D.R. Yonge, et al., Assessment of naphthalene biodegradation efficiency of Pseudomonas and Burkholderia strains tested in soil model systems, J. Chem. Technol. Biotechnol.: Int. Res. Process, Environ. Clean. Technol. 81 (2) (2006) 216 224. [116] I. Kelley, J.P. Freeman, C.E. Cerniglia, Identification of metabolites from degradation of naphthalene by a Mycobacterium sp, Biodegradation 1 (4) (1990) 283 290. [117] C.O. Jeon, W. Park, W.C. Ghiorse, E.L. Madsen, Polaromonas naphthalenivorans sp. nov., a naphthalenedegrading bacterium from naphthalene-contaminated sediment, Int. J. Syst. Evolut. Microbiology 54 (1) (2004) 93 97. [118] H. Pathak, D. Kantharia, A. Malpani, D. Madamwar, Naphthalene degradation by Pseudomonas sp. HOB1: in vitro studies and assessment of naphthalene degradation efficiency in simulated microcosms, J. Hazard. Mater. 166 (2 3) (2009) 1466 1473. [119] E. Jalilnejad, F. Vahabzadeh, Use of a packed-bed airlift reactor with net draft tube to study kinetics of naphthalene degradation by Ralstonia eutropha, Environ. Sci. Pollut. Res. 21 (6) (2014) 4592 4604. [120] P. Di Gennaro, P. Terreni, G. Masi, S. Botti, F. De Ferra, G. Bestetti, Identification and characterization of genes involved in naphthalene degradation in Rhodococcus opacus R7, Appl. Microbiology Biotechnol. 87 (1) (2010) 297 308. [121] E. Kim, G.J. Zylstra, Functional analysis of genes involved in biphenyl, naphthalene, phenanthrene, and mxylene degradation by Sphingomonas yanoikuyae B1, J. Ind. Microbiology Biotechnol. 23 (4) (1999) 294 302. [122] F.Z. Ferradji, S. Mnif, A. Badis, S. Rebbani, D. Fodil, K. Eddouaouda, et al., Naphthalene and crude oil degradation by biosurfactant producing Streptomyces spp. isolated from Mitidja plain soil (North of Algeria), Int. Biodeterior. Biodegrad. 86 (2014) 300 308. [123] J. Heider, A.M. Spormann, H.R. Beller, F. Widdel, Anaerobic bacterial metabolism of hydrocarbons, FEMS Microbiology Rev. 22 (5) (1998) 459 473. [124] S.S. Meena, R.S. Sharma, P. Gupta, S. Karmakar, K.K. Aggarwal, Isolation and identification of Bacillus megaterium YB3 from an effluent contaminated site efficiently degrades pyrene, J. Basic. Microbiology 56 (4) (2016) 369 378. [125] M.A. Alhefeiti, K. Athamneh, R. Vijayan, S.S. Ashraf, Bioremediation of various aromatic and emerging pollutants by Bacillus cereus sp. isolated from petroleum sludge, Water Sci. Technol. 83 (7) (2021) 1535 1547. [126] R. Morya, D. Salvachu´a, I.S. Thakur, Burkholderia: an untapped but promising bacterial genus for the conversion of aromatic compounds, Trends Biotechnol. 38 (9) (2020) 963 975. [127] W. Wang, L. Wang, Z. Shao, Polycyclic aromatic hydrocarbon (PAH) degradation pathways of the obligate marine PAH degrader Cycloclasticus sp. strain P1, Appl. Environ. Microbiology 84 (21) (2018) e01261 18. [128] T. Bugg, J.M. Foght, M.A. Pickard, M.R. Gray, Uptake and active efflux of polycyclic aromatic hydrocarbons by Pseudomonas fluorescens LP6a, Appl. Environ. Microbiology 66 (12) (2000) 5387 5392. [129] A.L. Juhasz, G.A. Stanley, M.L. Britz, Microbial degradation and detoxification of high molecular weight polycyclic aromatic hydrocarbons by Stenotrophomonas maltophilia strain VUN 10,003, Lett. Appl. Microbiology 30 (5) (2000) 396 401. [130] M.L. Narro, C.E. Cerniglia, Van Baalen, D.T. Gibson, Metabolism of phenanthrene by the marine cyanobacterium Agmenellum quadruplicatum PR-6, Appl. Environ. Microbiol. 58 (4) (1992) 1351 1359. [131] D. Warshawsky, T.H. Keenan, R. Reilman, T.E. Cody, M.J. Radike, Conjugation of benzo [a] pyrene metabolites by freshwater green alga Selenastrum capricornutum, Chem. Biol. Interact. 74 (1 2) (1990) 93 105. [132] X. Borde, B. Guieysse, O. Delgado, R. Mun˜oz, R. Hatti-Kaul, C. Nugier-Chauvin, . . . B. Mattiasson, Synergistic relationships in algal bacterial microcosms for the treatment of aromatic pollutants, Bioresour. Technol. 86 (3) (2003) 293 300. [133] T. Gentry, C. Rensing, I.A.N. Pepper, New approaches for bioaugmentation as a remediation technology, Crit. Rev. Environ. Sci. Technol. 34 (5) (2004) 447 494.

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[134] F.M. Bento, F.A. Camargo, B.C. Okeke, W.T. Frankenberger, Comparative bioremediation of soils contaminated with diesel oil by natural attenuation, biostimulation and bioaugmentation, Bioresour. Technol. 96 (9) (2005) 1049 1055. [135] Y. Teng, Y. Luo, M. Sun, Z. Liu, Z. Li, P. Christie, Effect of bioaugmentation by Paracoccus sp. strain HPD-2 on the soil microbial community and removal of polycyclic aromatic hydrocarbons from an aged contaminated soil, Bioresour. Technol. 101 (10) (2010) 3437 3443. [136] W.J. Thieman, M.A. Palladino, Introduction to Biotechnology, Second ed., Pearson, New York, 2009. [137] Pascucci, S. editor. Soil Contamination. Croatia: Rijeka; 2011. [138] F. Coulon, E. Pelletier, L. Gourhant, D. Delille, Effects of nutrient and temperature on degradation of petroleum hydrocarbons in contaminated sub-Antarctic soil, Chemosphere 58 (10) (2005) 1439 1448. [139] J.C. Okolo, Odu, “Effects of soil treatments containing poultry manure on crude oil degradation in a sandy loam soil, Appl. Ecol. Environ. Res. 3 (1) (2005) 47 53. [140] F. Chaillan, C.H. Chaineau, V. Point, A. Saliot, J. Oudot, Factors inhibiting bioremediation of soil contaminated with weathered oils and drill cuttings, Environ. Pollut. 144 (1) (2006) 255 265. [141] J. Oudot, F.X. Merlin, P. Pinvidic, Weathering rates of oil components in a bioremediation experiment in estuarine sediments, Mar. Environ. Res. 45 (2) (1998) 113 125. [142] C.H. Chaineau, G. Rougeux, C. Yepremian, J. Oudot, Effects of nutrient concentration on the biodegradation of crude oil and associated microbial populations in the soil, Soil. Biol. Biochem. 37 (8) (2005) 1490 1497. [143] L.M. Carmichael, F.K. Pfaender, The effect of inorganic and organic supplements on the microbial degradation of phenanthrene and pyrene in soils, Biodegradation 8 (1) (1997) 1 13.

Further reading G.J. Ahammed, C.J. Gao, J.O. Ogweno, Y.H. Zhou, X.J. Xia, W.H. Mao, et al., Brassinosteroids induce plant tolerance against phenanthrene by enhancing degradation and detoxification in Solanum lycopersicum L, Ecotoxicol. Environ. Saf. 80 (2012) 28 36. K.H. Baek, H.S. Kim, H.M. Oh, B.D. Yoon, J. Kim, I.S. Lee, Effects of crude oil, oil components, and bioremediation on plant growth, J. Environ. Sci. Health, Part. A 39 (9) (2004) 2465 2472. B.H. Chen, Y.S. Lin, Formation of polycyclic aromatic hydrocarbons during processing of duck meat, J. Agric. food Chem. 45 (4) (1997) 1394 1403. J. Detmar, T. Rabaglino, Y. Taniuchi, J. Oh, B.M. Acton, A. Benito, et al., Embryonic loss due to exposure to polycyclic aromatic hydrocarbons is mediated by Bax, Apoptosis 11 (8) (2006) 1413 1425. M.M. El-Fouly, Effect of low concentrations of 3, 4-benzpyrene on growth and N-fractions of seedlings, Landwirtschaftliche Forsch. 33 (1) (1980) 108 117. P.J. Harvey, B.F. Campanella, P.M. Castro, H. Harms, E. Lichtfouse, A.R. Scha¨ffner, et al., Phytoremediation of polyaromatic hydrocarbons, anilines and phenols, Environ. Sci. Pollut. Res. 9 (1) (2002) 29 47. K. Hussain, R.R. Hoque, S. Balachandran, S. Medhi, M.G. Idris, M. Rahman, et al., Monitoring and risk analysis of PAHs in the environment, Handb. Environ. Mater. Manag. (2018) 1 35. J.P. Incardona, T.K. Collier, N.L. Scholz, Defects in cardiac function precede morphological abnormalities in fish embryos exposed to polycyclic aromatic hydrocarbons, Toxicol. Appl. Pharmacol. 196 (2) (2004) 191 205. I.W. Jarvis, C. Bergvall, M. Bottai, R. Westerholm, U. Stenius, K. Dreij, Persistent activation of DNA damage signalling in response to complex mixtures of PAHs in air particulate matter, Toxicol. Appl. Pharmacol. 266 (3) (2013) 408 418. M. Krauss, W. Wilcke, C. Martius, A.G. Bandeira, M.V. Garcia, W. Amelung, Atmospheric versus biological sources of polycyclic aromatic hydrocarbons (PAHs) in a tropical rain forest environment, Environ. Pollut. 135 (1) (2005) 143 154. M. Kummerova, L. Slova´k, I. Holoubek, Phytotoxicity studies of benzo [a] pyrene with Lactuca sativa, Toxicol. Environ. Chem. 51 (1 4) (1995) 197 203. M. Kummerova, J. Krulova, S. Zezulka, J. Triska, Evaluation of fluoranthene phytotoxicity in pea plants by Hill reaction and chlorophyll fluorescence, Chemosphere 65 (3) (2006) 489 496. S.H. Lee, S. Lee, D.Y. Kim, J.G. Kim, Degradation characteristics of waste lubricants under different nutrient conditions, J. Hazard. Mater. 143 (1 2) (2007) 65 72.

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3. Toxicity of polyaromatic hydrocarbons and their biodegradation in the environment

R. Li, L. Zhao, L. Zhang, M. Chen, J. Shi, C. Dong, et al., Effects of ambient PM2. 5 and 9-nitroanthracene on DNA damage and repair, oxidative stress and metabolic enzymes in the lungs of rats, Toxicol. Res. 6 (5) (2017) 654 663. X. Li, P. Li, L. Yan, J. Chen, T. Cheng, S. Xu, Characterization of polycyclic aromatic hydrocarbons in fog rain events, J. Environ. Monit. 13 (11) (2011) 2988 2993. X. Liao, Z. Wu, X. Ma, X. Gong, X. Yan, Interactive effects of PAHs with different rings and as on their uptake, transportation, and localization in As hyperaccumulator, Environ. Sci. Pollut. Res. 24 (33) (2017) 26136 26141. H. Liu, D. Weisman, Y.B. Ye, B. Cui, Y.H. Huang, A. Colo´n-Carmona, et al., An oxidative stress response to polycyclic aromatic hydrocarbon exposure is rapid and complex in Arabidopsis thaliana, Plant. Sci. 176 (3) (2009) 375 382. L. Luiselli, G.C. Akani, An indirect assessment of the effects of oil pollution on the diversity and functioning of turtle communities in the Niger Delta, Nigeria, Anim. Biodivers. Cons. 26 (1) (2003) 57 65. B. Maliszewska-Kordybach, B. Smreczak, Effect of PAH-contaminated soil on some plants and microorganisms, in: V. Sasek, J.A. Glaser, P. Baveye (Eds.), The Utilization of Bioremediation to Reduce Soil Contamination: Problems and Solutions, 2013, pp. 177 185. M. Manikkam, C. Guerrero-Bosagna, R. Tracey, M.M. Haque, M.K. Skinner, Transgenerational actions of environmental compounds on reproductive disease and identification of epigenetic biomarkers of ancestral exposures, PLoS one 7 (2) (2012) 31901. N.N. Ozdnyakova, S.A. Balandina, E.V. Dubrovskaya, C.N. Golubev, O.V. Turkovskaya, Ligninolytic basidiomycetes as promising organisms for the mycoremediation of PAH-contaminated Environments, Proc. IOP Conf. Ser. Earth. Environ. Sci. (2018) 012071. P.S.S. Rao, S. Kumar, Polycyclic aromatic hydrocarbons and cytochrome P450 in HIV pathogenesis, Front. Microbiology 6 (2015) 550. C. Riccardi, P. Di Filippo, D. Pomata, M. Di Basilio, S. Spicaglia, F. Buiarelli, Identification of hydrocarbon sources in contaminated soils of three industrial areas, Sci. Total. Environ. 450 (2013) 13 21. S. Roy, O. Ha¨nninen, Pentachlorophenol: uptake/elimination kinetics and metabolism in an aquatic plant, Eichhornia crassipes, Environ. Toxicol. Chem. Int. J. 13 (5) (1994) 763 773. S. Roy, C.K. Sen, O. Ha¨nninen, Monitoring of polycyclic aromatic hydrocarbons using ‘moss bags’: bioaccumulation and responses of antioxidant enzymes in Fontinalis antipyretica Hedw, Chemosphere 32 (12) (1996) 2305 2315. Y. Shen, J. Du, L. Yue, X. Zhan, Proteomic analysis of plasma membrane proteins in wheat roots exposed to phenanthrene, Environ. Sci. Pollut. Res. 23 (11) (2016) 10863 10871. Y. Shen, J. Li, R. Gu, L. Yue, X. Zhan, B. Xing, Phenanthrene-triggered Chlorosis is caused by elevated Chlorophyll degradation and leaf moisture, Environ. Pollut. 220 (2017) 1311 1321. Y. Shen, J. Li, R. Gu, X. Zhan, B. Xing, Proteomic analysis for phenanthrene-elicited wheat chloroplast deformation, Environ. Int. 123 (2019) 273 281. R.J. Strasser, A. Srivastava, M. Tsimilli-Michael, The fluorescence transient as a tool to characterize and screen photosynthetic samples, Probing Photosynthesis: Mechanisms, Regul. Adapt. (2000) 445 483. A. Tarantini, A. Maıˆtre, E. Lefe`bvre, M. Marques, A. Rajhi, T. Douki, Polycyclic aromatic hydrocarbons in binary mixtures modulate the efficiency of benzo [a] pyrene to form DNA adducts in human cells, Toxicology 279 (1 3) (2011) 36 44. W.K. Vogelbein, J.W. Fournie, P.A. Van Veld, R.J. Huggett, Hepatic neoplasms in the mummichog Fundulus heteroclitus from a creosote-contaminated site, Cancer Res. 50 (18) (1990) 5978 5986. X.L. Yin, L. Jiang, N.H. Song, H. Yang, Toxic reactivity of wheat (Triticum aestivum) plants to herbicide isoproturon, J. Agric. Food Chem. 56 (12) (2008) 4825 4831. K. Yoshimura, K. Miyao, A. Gaber, T. Takeda, H. Kanaboshi, H. Miyasaka, et al., Enhancement of stress tolerance in transgenic tobacco plants overexpressing Chlamydomonas glutathione peroxidase in chloroplasts or cytosol, Plant. J. 37 (1) (2004) 21 33.

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C H A P T E R

4 Application of green chemistry for environmental remediation Manoj Kumar Banjare1,2, Kamalakanta Behera3, Ramesh Kumar Banjare4, Mamta Tandon1, Siddharth Pandey5 and Kallol K. Ghosh2 1

MATS School of Sciences, MATS University, Pagaria Complex, Raipur, Chhattisgarh, India 2 School of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur, Chhattisgarh, India 3Department of Chemistry, University of Allahabad, Prayagraj, Uttar Pradesh, India 4 Department of Chemistry (MSET), MATS University, Gullu Campus, Raipur, Chhattisgarh, India 5Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, Delhi, India

4.1 Introduction The development of “green materials” is prompted by the concentration and variety of environmental toxins that are rising [1]. The environmental impact of these chemical products is addressed through green chemistry and the procedures used to create them [2]. In this chapter, we will exclusively focus on the latter, where the product is already known and where the objective to build a green manufacturing technique was used. Green chemistry gets rid of trash at the source. In other words, it is mostly end-of-pipe pollution avoidance rather than waste. The primary tenet of green chemistry is that prevention is preferable to cure [3]. The pharmaceutical industry uses toxic chemicals and a particularly challenging manufacturing procedure that results in a disproportionately large amount of harmful substances [4]. These dangerous compounds have negative effects on the environment and nature. To lessen pollution, green chemistry offers a technological and environmentally sound substitute. In the latter half of the 20th century, rapid advancements in science and technology generated tremendous economic growth and raised standards of living. In the world’s industrialized regions, “green” or “sustainable chemistry” is a term used to describe the creation of chemical products and processes that reduce or eliminate the

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4. Application of green chemistry for environmental remediation

usage and manufacturing of hazardous substances [5]. It comprises developing a new area of chemistry using ecological approaches, reducing or eliminating the use of hazardous substances in chemical processes, as well as using harmful and toxic intermediates and products [6]. Each reaction must have three environmentally friendly elements to be deemed “green”: solvent, reagent or catalyst, and energy usage [7]. Some of the main strategies used to achieve the environmental protection and financial gain objectives of green chemistry include catalysis, biocatalysis, the use of alternative renewable raw materials (biomass), alternative reaction media [water, ionic liquids (ILs), supercritical fluids], alternative reaction conditions (microwave activation, mechanochemistry and ultrasound) and new photocatalytic reactions [8]. Green chemistry, also known as environmentally safe, safe and sustainable chemistry, is the development and use of chemical products and processes that reduce or eliminate the use and production of hazardous compounds [9]. Green chemistry aims to lessen and potentially eliminate the risk rather than limiting it by regulating exposure to dangerous chemicals, disputing the necessity of risk reduction through exposure control [10]. It is unnecessary to worry about removing dangerous substances from the environment or limiting exposure to them because there is no risk if they are not utilized or produced. The goal of green chemistry is to reduce waste, the price of raw materials, risks, energy consumption and environmental impact. Because of their ecofriendly nature, ILs have found extensive use in environmental cleanup [11].

4.2 History Catalysis, atom-economical synthesis, degradable materials and other fields that were developed before the field’s founding served as the foundation for green chemistry and substitute solvents [12]. Early in the 1990s, when green chemistry was established, there was a widespread concern about possible negative effects on human health and the environmental effects of industrial chemicals, waste, pollution and process byproducts in individuals’ daily life [7]. Instead of continuing to defer to lawyers, lawmakers and regulators to proactively address these pressing issues, chemical community members centred on a shared objective to create chemical products and procedures that reduce or reduce to zero the usage and production of hazardous substances, says Yale’s Paul Anastas University, one of the pioneers in green chemistry [13]. The Pollution Prevention Act of 1990, which changed the regulatory policy from pollution control to pollution prevention as the most effective way to manage a variety of environmental problems [14], was passed during the 1990s, which also saw the creation of the area of sustainability. Numerous items and goods on the market today contain hundreds of chemicals or chemical compounds, which add up significantly in material inventories and may one day become liabilities [15]. Supply chains are also becoming more globally interconnected, but less information is being shared on the chemicals used in manufacturing and consumer goods. These restrictions make it difficult to implement measures across the product life cycle, such as limiting chemical releases during production, lowering consumer exposure, and lowering chemical emissions during recycling and final disposal [16].

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4.4 Ionic liquids

4.3 Concept of green chemistry In the Untied States, a research initiative called “green chemistry” has arisen from the cooperative work of a university unit, the independent research community, industry, the technical community and legislative organizations to reduce pollution [17]. The new strategy deals with relevance of green chemistry chemical substances in a way that reduces the risk to the environment and human health. Additionally known as: 1. 2. 3. 4.

Chemistry that is safe for the environment Chemically sound Atomic riches Good-looking design chemistry

4.4 Ionic liquids Organic salts with a low melting point (100 C) are ILs and are frequently employed as solvents [18]. When compared to conventional solvents, most ILs offer greener production processes, making them potential replacements for volatile organic compounds (VOCs) [19]. ILs have high flexibility, excellent thermal and chemical stability, and low vapour pressures as compared to other compounds. ILs can be broadly categorized into the following four groups according to the type of cations they contain: ILs with bases in imidazolium, pyridinium, quaternary ammonium and quaternary phosphonium are shown in Figs. 4.1 and 4.2 [20]. Despite its tardy beginning, IL research in China has advanced quickly. It has special benefits in the areas of electrochemistry, organic reaction and gas liquid separation [21]. Amphiphilic IL molecular structures are shown in Fig. 4.3. The first ILs are discovered in the 1980s and these are based on their physical properties. The first generation of ILs is depicted in Fig. 4.2 as cations, such as imidazolium, pyridinium, ammonium, pyrrolidinium, sulphonium and phosphonium, and anions, such as chloride, bromide and iodide. The use of ILs in materials for different purposes, such as energetic materials, lubricants, metal ion complexation, etc., is becoming more and more popular in the 21st century [14 16,22]. When designing new functional materials, ILs with a unique attribute of both FIGURE 4.1 Structure of organic and inorganic cations and anions of ionic liquids.

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4. Application of green chemistry for environmental remediation

R3 R2

R4

N N

R1

N

R3

2nd Generation Anions

R1 Pyridinium

Imidazolium

1st Generation Anions

CI

R1 R2 pyrrolidinium

O +

N

N N R1 +

O

R2

R 1 R2 Morpholinium

1st

R3 R1 P+ R4

Generation Cations

R2

Sulfonium

BF4

Ammonium

R2 S R1 + R3

N

- - + Br, I AlCl

PF6 O

+

-

+

R3

R2

R2 R 1 N R4

Phosphonium

R

N N

R1 +

3rd Generation Anions

R2 N R1

R2

functionalized Imidazolium

2nd Generation Cations

F3C S O O

O H3C S O O

NC N CN SCN

O

O

O

O

SO

R O S O H 3C

O N O S S F3C O O CF 3

F H

FO O

S O FF

Anions Cations

FIGURE 4.2 List for the generation of ionic liquids. FIGURE 4.3 Structure of amphiphilic ionic liquid molecule.

Br- + N N Hydrophilic

Hydrophobic

cations and anions can be separately adjusted while preserving their essential desirable characteristics. IL-based research that is focused on the physical and chemical characteristics of ILs was carried out in the year 2000. In addition to being used as organic reaction solvents, ILs are also used as lithium battery electrolytes and in the electroplating process, extraction, biotechnology, colloidal science atmospheric remediation, soil remediation, atomic economic reaction, water restoration and the use of solar cells in electrochemistry provide evidence (Figs. 4.4 and 4.5). The integration of IL technology with other classical technologies has been thoroughly researched. Functionalized ILs with cations and anions that specifically target organic moieties are created by the specifications. The features of ILs, such as their thermal stability, viscosity, surface tension, etc., have also been altered using quantum chemistry calculations and molecular dynamics simulations [23]. In addition to hydrogen bonding and interactions, the type and size of anions and cations, as well as the equilibrium between Coulomb and van der Waals contacts, determine the physical and chemical properties of ILs [24]. The affinity of ILs for the target molecules makes them suitable adsorbents for inorganic or organic

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4.4 Ionic liquids

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FIGURE 4.4 A general survey of recent applications of ionic liquids.

contaminants. They are appealing as media and templates when creating nanomaterials with unique morphologies due to their poor higher level of orderliness, reduced interfacial tension and energy, and coordination ability brought on by the ease with which hydrogen bonds can form [25]. As a result, the study of ILs is crucial from the perspective of both practical applications and fundamental theoretical considerations.

4.4.1 Characteristics of ionic liquids Its high separation efficiency, lack of secondary contamination and low consumable requirements in the restoration of the aquatic environment show the typical traits and unique benefits of ILs in environmental remediation [26]. It can successfully lessen the toxicity of contaminants during soil remediation. Pollutant removal in the atmospheric cleanup may occasionally be combined with creative use of the contaminants [27]. The use of ILs in environmental cleanup and green preparation is expected to increase in the future. Fig. 4.6 shows the industrial uses of ILs. ILs have been used to cure environmental contamination as a green option. As illustrated in Fig. 4.6 [28], ILs provide many advantages over traditional treatment approaches for environmental remediation, including low toxicity, environmental friendliness, high extraction

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4. Application of green chemistry for environmental remediation

FIGURE

4.5 Application

of

ionic

liquids.

FIGURE 4.6 Industrials uses of ionic liquids.

Academia

Biodiversity

Ionic liquids

Industry

Waste water

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4.5 Water as a solvent for organic reactions

73

efficiency, the potential for reuse and minimum energy use. The pH-dependent fluctuation in the partition coefficient between ILs and water makes it possible to separate and enrich heavy metals, recover them from the IL medium and then reuse them [29]. Between 90% and 99% of heavy metals like cadmium, copper and zinc may be removed by ILs. In 2003, Wei et al. [30] used dithizone as the chelating agent to successfully extract Hg21, Pb21 and Cd21 from the aqueous phase into 1-butyl-3-methylimidazolium hexafluorophosphate. For the effective removal of Cr2O722 from wastewater, two imidazoliumbased cationic polymeric nanoparticles based on tetraphenylmethane building blocks (CPN-tpm) with various counterions were devised and built. Such nanoparticles open the door for the development of cationic polymeric nanoparticles as a new class of adsorbent for wastewater treatment [31] in addition to providing a quick and effective method to improve a cationic polymer’s adsorption performance towards Cr2O722 by a simple exchange of the counter anion. In recent years, researchers have discovered that putting ILs onto the surface of graphene can enhance its functionality and adsorption impact. The removal of hexavalent chromium from wastewater by Rajesh et al. [32] was studied in 2013. They used a composite consisting of exfoliated graphene oxide (EGO) and quaternary ammonium ILs. The conversion of dichromate ions to the most innocuous Cr31 ion makes it possible to regenerate the adsorbents. Adsorbents impregnated with tetraoctylammonium bromide (IL) showed a higher adsorption capacity and faster adsorption kinetics in actual wastewater samples. Nasrollahpour et al. created a unique method in 2017 [33] for the separation and enrichment of mercury utilizing magnetic graphene oxide (GO) nanoparticles modified by ILs. Due to its high water solubility and difficulty in separating it from water, GO cannot be used as an adsorbent from the aqueous phase. Magnetism, however, can be successfully added to GO to overcome this limitation. By employing nanocomposites constructed of 1-vinyl-3-butylimidazolium hexafluorophosphate-modified magnetic activated carbon (IL@mAC), Bazrafshan et al. [34] were able to remove tetracycline from wastewater. The best elimination efficiency of nearly 88% was generated by the settings of pH7, 303K reaction temperature, 0.06 g/kg dosage and 135 min reaction time. It has been used as an adsorbent to boost the concentration of fluoroquinolone antibiotics in water samples.

4.5 Water as a solvent for organic reactions Using water as a solvent for organic reactions has many advantages, including increasing reactivities and selectivities, streamlining workup procedures, allowing the catalyst to be recycled, allowing mild reaction conditions and allowing protecting-group-free synthesis, among others [35]. Besides being beneficial in and of itself, as in nature, we should consider water as a flexible solvent for natural chemistry. Because of hydrophobic properties, employing water as a solvent frequently not only increases reaction selectivity but also speeds up reactions, even when reactants are used sparsely. Whether it is soluble or not in this medium, it is a cheap and “green” solvent for use in manufacturing. That some effects seen in water solutions can also be seen in water suspensions is a discovery that argues that even insoluble substances may benefit from being employed in water.

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4. Application of green chemistry for environmental remediation

However, the primary cause is reality. Because the hydrophobic effect produces such amazing novel chemistry, it is important to pursue using water as a solvent. The aforementioned substrate binding, aromatic chlorination, ribonuclease mimics, acylations by esters, mimics of metalloenzymes, amino acid syntheses, aldol condensations, Diels Alder processes, heterocyclic carbene chemistry, carbonyl selective oxidations and reductions [36 38]. The geometries were also chosen using the hydrophobic effect for some significant reactions of transition states.

4.6 The benefits of green chemistry The following benefits of green chemistry are shown in Fig. 4.7 [39]. 1. Economical 2. Energy efficient

Economical Found in water solutions

Energy efficient

Protects human health and the environment

Lowers cost of production and regulation

Benefits of Green Chemistry

Healthier workplaces and communities

Less wastes

Safer products

Fewer accidents

FIGURE 4.7 The benefits of green chemistry.

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4.10 Most efficient method for addressing a variety of environmental problems

3. 4. 5. 6. 7. 8. 9.

75

Lowers cost of production and regulation Fewer wastes Fewer accidents Safer products Healthier workplaces and communities Protects human health and the environment The observation that several phenomena found in water solutions can also be seen

4.7 Twelve principles of green chemistry In Fig. 4.7, the advantages of green chemistry are depicted [40 42].

4.8 Green and sustainable chemistry is gaining ground The ideas of green and sustainable chemistry have garnered a lot of attention from people all around the world due to their potential to develop and improve chemistry to help achieve the SDGs and their aims (Fig. 4.8). The idea of “green chemistry” was shaped by the well-known 12 principles that Anastas and Warner published in 1998, but more recently, “sustainable chemistry” has evolved as a closely related but more comprehensive concept [2]. To bring about such a transformation, it will be important to go beyond traditional chemistry innovation approaches and incorporate systems thinking and systems design that can have positive effects on the molecular level as well as the global scale [43].

4.9 Opportunities for green and sustainable chemistry New opportunities to promote sustainability have been established throughout the value chain as a result of recent advancements in chemistry and sophisticated materials. The creation of sustainable building materials, improvements to the recycling and biodegradability of a variety of items, and the transformation of waste and carbon dioxide (CO2) into chemical feedstocks and functional products are a few of them [44]. Greener and more sustainable innovation at the nexus of chemistry, biology and computer science is particularly promising (UNEP 2019). The Sustainable Development Goals (SDGs) act as a valuable framework and present fresh chances to promote the green and sustainable chemical agenda. Many SDGs, including SDG 2 (Zero Hunger), SDG 3 (Good Health and Well-Being) and SDG 4, might be directly advanced by green and sustainable chemistry (Clean Water and Sanitation).

4.10 Most efficient method for addressing a variety of environmental problems Although there are discrepancies in how green and sustainable chemistry is defined, there is evidence, albeit few, suggesting the recent years, both the supply and demand for

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FIGURE 4.8 Twelve principles of green chemistry.

greener and more sustainable chemistry products have drastically expanded [45]. According to BCC Research (2016), the worldwide green chemistry market had a value of more than US$50 billion in 2015 and is expected to reach US$167 billion by 2027. (ReportLinker 2020). The three main market expansion regions are North America, Western Europe, and Asia and the Pacific (Pike Research 2011) [46].

4.11 Water treatments Wastewater that has been properly treated offers a lot of potential as a supply of water for industries, homes and crops. Municipal water has long been cleaned using an aluminium-based substance called alum, which has been a standard procedure. According to studies, Alzheimer’s and other diseases are brought on by water containing excessive

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amounts of aluminium ions [47]. Utilizing biodegradable flocculants, such as tamarind seeds, kernel powder, and a mixture of starch and alum, is the easier option. These have proven to be less toxic and just as effective as an alum. The wastewater industry is still working to improve research and development that is economical, innovative and environmentally beneficial. Treatment facilities that use biological treatment with jet aeration have been planned, engineered and produced four activated carbon filters, four sand filters, sand filters, four activated carbon filters and a container for reactivated carbon. Since biological waste is eliminated as a result of carbon being reactivated and subsequently reused, this method is environmentally friendly. The foregoing has been Siemens Water Technologies’ invention. Clean Earth Environmental Company has developed a method known as silica, the use of microcapsules. Instead of using neutralization or precipitation techniques in this case, pollutant encapsulation in it is possible to create a persistent silica matrix even in harsh environmental circumstances. The metals that are enclosed are efficiently immobilized, lowering the risk of environmental contamination and health risks. Various different wastewater treatment methods have been developed based on the types of contaminants that are present [48].

4.12 Advantages of green chemistry Advantages of green chemistry are shown in Fig. 4.9.

4.12.1 Human health 1. Cleaner air: fewer lungs are harmed by hazardous chemical releases into the atmosphere [49]. 2. Cleaner water: environmental pollution from hazardous chemical waste is reduced, which leads to cleaner drinking and recreational water. FIGURE 4.9 Benefits of green chemistry.

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3. Lessening the use of hazardous products, the requirement for personal protective equipment and the likelihood of accidents for workers in the chemical sector (e.g., fires or explosions). 4. Safer consumer products of all kinds will be sold and available; certain products, like medicines, will be manufactured with less waste, while others, like pesticides and cleaning supplies, will take the place of less safe products. 5. Less exposure to dangerous substances, including safer insecticides that exclusively poison specific pests and safer food, such as persistent toxic compounds that can enter the food chain.

4.12.2 Environment 1. A lot of chemicals end up in the environment intentionally (like pesticides when they are used), accidentally (like emissions during manufacturing), or through disposal [50]. Green substances either degrade into harmless substances or are recycled for future use. 2. Plants and animals suffer less when dangerous substances are prevalent in the environment. 3. Smog, ozone depletion and global warming are less likely to occur. 4. Less toxicity-related ecosystem disruption. 5. Lessening of landfill usage, especially for hazardous trash.

4.12.3 Economy and business 1. Fewer synthetic stages, which frequently enable quicker product manufacturing, increased plant capacity, and energy and water savings [51]. 2. Less waste, with no need for costly cleanup, hazardous waste disposal or end-of-pipe treatments. Permit waste products to replace purchased feedstocks III. Improve performance so that less product is required to provide the same level of output. 3. Reducing the consumption of petroleum products, sluggish their depletion, and avoiding hazards and price fluctuations. 4. Increasing sales to consumers by obtaining and displaying a label for safer products (such as Safer Choice labelling). 5. A smaller or more compact manufacturing facility due to higher throughput. 6. Increased client and chemical manufacturer competition.

4.13 Green chemistry in day-to-day life Green chemistry in day-to-day life is shown in Fig. 4.10. 1. Green dry cleaning: Perchloroethylene (PERC), a solvent used in dry cleaning, is now recognized as a groundwater contaminant and may even be carcinogenic. By using liquid CO2 and a surfactant, the micelle method created by Joseph De Semons, Timothy R. Mack and James Mc Clain eliminated the need for halogenated solvents [52]. 2. Versatile bleaching agents: Wood is used to make paper (contains 70% polysaccharides and 30% lignin). The lignin should be exclusively eliminated to produce a paper of high quality [53].

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4.13 Green chemistry in day-to-day life

Green dry cleaning

Reusable water bottle

Versatile bleaching agents

Versatile bleaching agents

solar array

Polysaccharide Polymers

Glucose is a substitute

FIGURE 4.10 Green chemistry in day-to-day life.

3. Tamarind seed kernel powder: It is typically dumped as agricultural waste and works well to clear up murky municipal and industrial wastewater. At the moment, such water is treated using Al-salt. Alum has been discovered to increase the number of harmful ions in treated water, which may contribute to disorders like Alzheimer’s. However, kernel powder is cost-effective, biodegradable and non-toxic. For the experiment, four flocculants were utilized, including tamarind seed kernel powder, a mixture of the powder and starch, and starch and alum [54]. 4. Glucose is a substitute for the product chemicals used in the synthesis of chemicals from glucose. Biotechnological techniques are employed to regulate the generation of scented compounds. Substances such as catechol, adipic acid and hydroquinone are both chemicals of something that could be artificial yet still be necessary [55]. 5. Polysaccharide polymers: They constitute a crucial class of compounds. Substances that have common packaging. They have their risky repercussions. A wide variety of Compounds can be used for profit. Due to the polysaccharide Feedstock must be utilized as initial supplies because it is a far more environmentally friendly feedstock [56]. 6. The solar array is among the most well-known instances of green technology: A technological example is the solar cell. A real solar cell uses the photovoltaic method to convert light energy into electrical energy [57].

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7. Reusable water bottle: This uncomplicated invention is under the green category. Drinking lots of water is healthy for you. Reducing plastic waste has a big positive impact on the environment. Stylish reusable water bottle are healthy, environmentally beneficial and green. Technology utilized in green buildings uses some environmentally friendly techniques to lessen their impact on the environment, solar design, natural ventilation, recycled green roofing and passive materials A structure built by a builder can have a significantly smaller carbon footprint than a typical structure. These techniques not only benefit the environment but also enable the creation of beautiful structures [58].

4.14 Green solution to turn turbid water clear Powdered tamarind seed kernels, which are typically dumped as agricultural waste, work well to clear up wastewater from both municipal and industrial sources. At the moment, such water is treated using Al-salt. It has been discovered that alum causes diseases like Alzheimer’s disease by increasing harmful ions in treated water. However, kernel powder is cost-effective, biodegradable and nontoxic [59]. Clay and water were combined in the proper amounts to create flocculants with slurries. The outcome demonstrated that the powder and suspended particles aggregated into more porous materials which made it easier for water to condense and form larger aggregates. The results showed that the powder and suspended particles aggregated into more porous materials which made it easier for water to seep out, consolidate and produce bigger volumes of water. However, starch flocks were found to be less porous and lighter in weight, which made it difficult for water to move through them. The research shows that the powder has the potential to be an effective substitute for more widely used flocculants like K2SO4Al2(SO4)30.24H2O (potash alum).

4.15 The three primary environmental restoration and cleanup methods Remediation is the process of removing toxins from areas that have been harmed by industrial, manufacturing, mining and commercial activity. Remediation involves a broad range of processes, including detection, investigation, assessment, choosing a course of corrective action, actual cleanup and site reconstruction. In a variety of contaminated locations, the following cleanup methods are routinely employed [60]. Common types of remediation are shown in Fig. 4.11.

4.16 Soil remediation Several factors have an impact on the condition of the soil. Environmental remediation includes all techniques and processes used to remove contaminants from soil. Soil

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4.16 Soil remediation

FIGURE 4.11

Sediment Remediation

Common types of remediation.

Soil Remediation

Groundwater Remediation

contamination poses many risks and concerns to people’s health and the environment, whether they come into direct contact with it, consume it, or introduce it into the food supply chain. Soil remediation techniques are used to remove a variety of soil contaminants, such as heavy metals, petroleum hydrocarbons, pesticides and radioactive materials [61]. These restorative techniques could be physical, chemical, thermal or biological, depending on the kind of contamination being eliminated [62]. Soil rehabilitation is done in a lot of different places. These are a few of those places or environments: 1. 2. 3. 4. 5. 6. 7. 8. 9.

Environments in cities Urban mining Opencast coal mines Raw material extraction sites Mining wastes Subsiding mining terrains Quarries and open-pit mines Peatlands Mining and raw material extraction areas

These locations undergo a comprehensive diagnostic evaluation that is carried out in three stages: 1. Preliminary site assessment: This is the initial phase of soil remediation, and it provides a qualitative evaluation of the site through analysis and interpretation of data gathered from witnesses, agency reports, geological and hydrological studies, and aerial photographs [63]. 2. Comprehensive site assessment: In this phase, the research is expanded upon by the collection of soil samples and the analysis of the findings [64]. 3. The actual implementation of the selected soil remediation procedures is covered in the third step, which also includes simulating solutions [65].

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4.17 Groundwater and surface water remediation Water has always been one of the most essential natural resources for maintaining the existence and sustainability of life systems. The quality of the water sources must be controlled and maintained to keep the safe levels for the desired application. Environmental remediation of industrial and potable-grade water has recently witnessed a push in enforcement due to the increase in industrial effluent discharge. Groundwater is the term used to describe water that is buried beneath rock and soil in the subsurface as well as water that is present in large subterranean aquifers. It must be drained out to reach the groundwater. Iron, chromium, selenium, fluoride and arsenic are some of the pollutants that are most frequently found in groundwater [66]. The first stage in assessing groundwater contamination is to look into potential sources of contamination. Leachate sources must be examined, and variations in water quality and cyclical fluctuations are a few factors that must be monitored. Groundwater degradation that originates from the land surface can be brought on by a variety of factors, including infiltration of contaminated surface water, waste from land and water disposal, tailings and stockpiles, dumps, fertilizers and pesticides, unintentional spills, and other airborne particulate matter [67]. Groundwater degradation from above the water table may be brought on by surface impoundments, septic tanks, landfills, excavated waste disposal systems, leaks from underground pipes and storage tanks, sumps and dry wells, or even graves. There are several ways to preserve and replenish groundwater, some of which are as follows [68]. Approaches to protecting and restoring groundwater are shown in Fig. 4.12.

FIGURE 4.12 Approaches to protecting and restoring groundwater.

Pumping systems

Ground water barrier systems

Biodegra -dation

Protecting and Restoring Ground Water

Intercept or systems

In situ treatments

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4.18 Remediation of sediments Sediments are materials that are transported into aquatic ecosystems, and they include things like clay, organic debris, hydrated oxides, more soil and water [69]. Chemical and physical characteristics of sediments are investigated. Sediment remediation technologies use physical, chemical and biological processes to either remove toxins or change them into less dangerous forms. In situ and ex-situ techniques are used in sediment cleanup solutions [70]. The process of remediation of sediments is shown in Figs. 4.13 and 4.14.

4.19 Environmental remediation The world is expanding at an unstoppable rate today, as it did in the 21st century. Some of the biggest environmental problems are brought on by the expanding number of industries and mass production. The garbage produced by all of these enterprises is the main cause of environmental deterioration. Additionally, it is to blame for rising pollution levels. The air, water and natural resources are contaminated in large part because of the chemicals utilized. Environmental remediation, put simply, is the act of eliminating harmful and contaminated substances from the soil, water, air and natural environment [14]. The goal is to reduce the hazards that come with them. The word “remediation” in this context indicates “to correct the situation”. It speaks of sanitizing the environment for the benefit of humanity and to protect against the different health risks that pollution presents. According to the law, the industries that cause environmental deterioration must contribute to the solution.

FIGURE 4.13 In situ technologies for sediment remediation.

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FIGURE 4.14

4. Application of green chemistry for environmental remediation

Ex-situ remediation technologies.

Environmental remediation is focused on removing pollutants or poisons from environmental media, such as soil, groundwater, sediment or surface water. Remedial action may also be based on assessments of the risks to human health and the environment where there are no legislative requirements or when the standards are advisory [71].

4.19.1 Environmental remediation steps Today, they take the following actions when they target a location for remediation [72] and the environmental remediation steps are shown in Fig. 4.15. 1. Thorough evaluation of the location Environmental cleanup firms start with this step. This evaluation of allegedly polluted places takes into account various factors. The most crucial step is to understand the location’s trigger, the causes and the solutions to solve the situation. 2. Evaluation of the data The information obtained about the site in the first phase is next evaluated. Making decisions about what to accomplish and how to do it is required. The best option is chosen from a list of all potential choices. 3. Remediation The final and most crucial stage is to put everything from the preceding steps into practice. The specialists reclaim the contaminated areas while adhering to the required pattern. For a secure procedure, the right safety precautions are in place. Additionally, to guarantee the safety of the employees engaged in the remediation procedure.

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4.19 Environmental remediation

FIGURE 4.15

Environmental remediation

steps.

Remediaon Evaluaon of the data Thorough evaluaon of the locaon

4.19.2 Environmental sedimentation technologies The different technologies of environmental sedimentation are shown in Fig. 4.14 [73]. 4.19.2.1 Thermal desorption The technology for soil remediation is thermal desorption. A desorbed is used in the process to separate the contaminants from the soil or sludge, notable ones like oil, mercury or hydrocarbons. After that, an off-gas treatment system can either collect or eliminate the impurities [74]. 4.19.2.2 Excavation or dredging When working with VOCs, excavation operations might also need to include aerating the removed soil before moving it to a designated landfill. Thanks to recent advancements in bioaugmentation and biostimulation of the excavated material, semi-VOCs onsite can now be corrected [75]. 4.19.2.3 Surfactant enhanced aquifer remediation To facilitate desorption and recovery of bound-up, otherwise resistant non-aqueous phase liquid, the surfactant enhanced aquifer remediation process, also known as solubilization and recovery, involves infusing hydrocarbon mitigation agents or specialty surfactants into the subsurface [76] (Fig. 4.16). 4.19.2.4 Pump and treat The pump-and-treat method involves removing tainted groundwater with a submersible or vacuum pump and cleaning it by allowing it to gently run through a series of vessels that contain materials designed to adsorb the toxins from the groundwater [77]. 4.19.2.5 Solidification and stabilization Although the history of solidification and stabilization efforts is generally positive, there are many severe flaws about the longevity of solutions and potential long-term repercussions. The widespread use of cement in solidification/stabilization projects is being hampered by the CO2 emissions caused by its use [78].

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FIGURE 4.16

4. Application of green chemistry for environmental remediation

Different technologies of environmental sedimentation.

4.19.2.6 In situ oxidation Numerous pollutants in soil and groundwater can now be removed using new in situ oxidation technology. Chemical oxidation-based remediation calls for the injection of strong oxidants such as hydrogen peroxide, ozone gas, potassium permanganate or persulfates [79]. 4.19.2.7 Soil vapour extraction A good method for remediating contaminated soil is soil vapour extraction (SVE). “Multiphase extraction” (MPE) is an effective remediation method for soil and groundwater remediation. SVE and MPE treat the off-gas VOCs produced after vacuum removal of air and vapours (and VOCs) from the subsurface using a variety of technologies, including granular activated carbon (most frequently used historically), thermal and/or catalytic oxidation, and vapour condensation. For vapour streams with low VOC

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concentrations (below 500 ppmV), carbon is typically used, oxidation is typically used (up to 4000 ppmV), and vapour condensation is typically employed (for streams with high VOC concentrations) (above 4000 ppmV). A brief explanation of each method is given below [80]. 4.19.2.8 Nanoremediation Nanoremediation is the process of pollutant degradation or immobilization using nanoscale reactive agents. Injection or a pump-and-treat in situ procedure are two ways that nanoparticles are introduced into contact with the contamination in soil or groundwater. The nanomaterials then use redox processes to break down organic pollutants or adsorb to metals like lead or arsenic to immobilize them. With research into wastewater treatment, this technology has primarily been used in commercial settings for groundwater remediation [81]. Research is also looking into the possibility of using nanoparticles to clean up gases and soil. 4.19.2.9 Bioremediation Bioremediation is used to clean up a polluted region; it either alters the environment to promote the development of microorganisms or depends on natural microorganism activity to break down the target chemicals. The broad categories of biostimulation, bioaugmentation and natural recovery include bioremediation (natural attenuation). After the contaminated soils have been removed, either the polluted site is treated directly (in situ) or a different, more controlled site is utilized for bioremediation (ex situ) [82]. 4.19.2.10 Collapsing air microbubbles Self-collapsing air microbubbles have recently been researched as an alternative to chemicals for cleaning oil-contaminated sediments. Air microbubbles created in water without the use of any surfactants could be utilized to clear sediments polluted with oil. This approach has potential compared to the currently used, chemical-based (mainly surfactant-based) way of cleaning oil-contaminated sediments [83].

4.20 Conclusions We shall only discuss the use of green chemistry for environmental remediation in this chapter. Green chemistry gets rid of trash at the source, and it is mostly end-of-pipe pollution avoidance rather than waste. The primary tenet of green chemistry is that prevention is preferable to cure. It has special benefits in the areas of electrochemistry, organic reaction and gas liquid separation, among others. Soil contamination poses many risks and concerns to people’s health and the environment, whether they come into direct contact with it, consume it or introduce it into the food supply chain. Sediment remediation technologies use physical, chemical and biological processes to either remove toxins or change them into less dangerous forms. In situ and ex situ techniques are used in sediment cleanup solutions. It mentions cleaning up the environment for the good of humanity. Environmental remediation is focused on removing

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pollutants or poisons from environmental media, such as soil, groundwater, sediment or surface water.

Acknowledgements The HOD of the MATS School of Sciences at MATS University in Raipur, Chhattisgarh, is acknowledged by the writers.

Notes None of the writers have any financial conflicts to disclose.

Authors contribution All authors contributed to writing the book chapter. The book chapter’s finished form has been approved by all authors.

References [1] W. Mrozik, M. Ali Rajaeifar, O. Heidrich, P. Christensen, Environmental impacts, pollution sources and pathways of spent lithium-ion batteries, Energy Environ. Sci. 14 (2021) 6099 6121. [2] B.A.D. Marco, B.S. Rechelo, E.G. To´toli, A.C. Kogawa, H.R.N. Salgado, Evolution of green chemistry and its multidimensional impacts: a review, Saudi Pharm. J. 27 (1) (2019) 1 8. [3] J.C. Warner, A.S. Cannon, K.M. Dye, Environmental impact assessment review, Green. Chem. 24 (7 8) (2004) 775 799. [4] A. Maertens, E. Golden, T. Hartung, Avoiding regrettable substitutions: green toxicology for sustainable chemistry, ACS Sustain. Chem. Eng. 9 (23) (2021) 7749 7758. [5] M.E. Ayalew, T.S.M.A. Jeevan, The technology of green chemistry and its function in redox response and: environmentally friendly technology for sustainable development: assessment of recent findings, Adv. Chem. Eng. Sci. 12 (2022) 131 144. [6] O.V. Kharissova, B.I. Kharisov, C.M.O. Gonza´lez, Y.P. Me´ndez, I. Lo´pez, Greener synthesis of chemical compounds and materials, R. Soc. Open. Sci. 6 (11) (2019) 191378. [7] R.A. Sheldon, Metrics of green chemistry and sustainability: past, present, and future, ACS Sustain. Chem. Eng. 6 (1) (2018) 32 48. ˇ [8] M. Jukic, S. Djakovi´c, Z.F. Kovaˇcevi´c, J.V. Furac, Dominant trends of green chemistry, J. Chem. Chem. Eng. 54 (5) (2005) 255 272. [9] B. Aparecidade, M. Ba´rbara, S.R. Eliane, G.T. Ana, C.K. He´rida, R.N. Salgado, Evolution of green chemistry and its multidimensional impacts: a review, Saudi Pharm. J. 27 (1) (2019) 1 8. [10] A.S. Cannon, John C. Warner, The science of green chemistry and its role in chemicals policy and educational reform, J. Environ. Occup. Health Policy 21 (3) (2011) 499 517. [11] T. Welton, Ionic liquids in green chemistry, Green. Chem. 13 (2) (2011). 225-225. [12] P. Marino, P.R. Donnarumma, H.A. Bicalho, V.Q. Novoa, H.M. Titi, A.J. Howarth, A Step toward change: a green alternative for the synthesis of metal organic, ACS Sustain. Chem. Eng. 9 (48) (2021) 16356 16362. [13] R.B. Stewart, Environmental regulation and international competitiveness, Yale Law Journal, 102, 8, Symposium: Economic Competitiveness Law, The Yale Law Journal Company, Inc., 1993, 2039 2106. [14] I. Manisalidis, E. Stavropoulou, A. Stavropoulos, E. Bezirtzoglou, Environmental and health impacts of air pollution: a review, Front. Public Health 8 (2020). Available from: https://doi.org/10.3389/fpubh.2020.00014. [15] J. Jeevanandam, A. Barhoum, Y.S. Chan, A. Dufresne, M.K. Danquah, Review on nanoparticles and nanostructured materials: history, sources, toxicity and regulations, Beilstein J. Nanotechnol. 9 (2018) 1050 1074. Available from: https://doi.org/10.3762/bjnano.9.98.

Green Chemistry Approaches to Environmental Sustainability

References

89

[16] R.C. Thompson, C.J. Moore, F.S.V. Saal, S.H. Swan, Plastics, the environment and human health: current consensus and future trends, Philos. Trans. R. Soc. Lond. B Biol. Sci. 364 (1526) (2009) 2153 2166. [17] V.G. Zuin, I. Eilks, M. Elschami, K. Ku¨mmerer, Education in green chemistry and in sustainable chemistry: perspectives towards sustainability, Green. Chem. 23 (2021) 1594 1608. [18] M. Koel, Ionic liquids in chemical analysis, Crit. Rev. Anal. Chem. 35 (2005) 177 192. Available from: https://doi.org/10.1080/10408340500304016. [19] Z. Lei, B. Chen, Y.M. Koo, D.R.M. Farlane, Introduction: ionic liquids, Chem. Rev. 117 (10) (2017) 6633 6635. [20] S.L. Piper, M. Kar, D.R.M. Farlane, K. Matuszek, J.M. Pringle, Ionic liquids for renewable thermal energy storage a perspective, Green. Chem. 24 (2022) 102 117. [21] V. Kamysbayev, V. Srivastava, N.B. Ludwig, O.J. Borkiewicz, H. Zhang, J. Ilavsky, et al., Nanocrystals in molten salts and ionic liquids: experimental observation of ionic correlations extending beyond the debye length, ACS Nano 13 (5) (2019) 5760 5770. [22] J. Hopewell, R. Dvorak, E. Kosior, Plastics recycling: challenges and opportunities, Philos. Trans. R. Soc. Lond. B Biol. Sci. 364 (1526) (2009) 2115 2126. [23] Z. Xu, Z. He, X. Quan, D. Sun, Z. Miao, H. Yu, et al., Molecular simulations of charged complex fluids: a review, Chin. J. Chem. Eng. 31 (2021) 206 226. [24] R. Hayes, G.G. Warr, R. Atkin, Structure and nanostructure in ionic liquids, Chem. Rev. 115 (13) (2015) 6357 6426. [25] H. Heinz, C. Pramanik, O. Heinz, Y. Ding, R.K. Mishra, D. Marchon, et al., Nanoparticle decoration with surfactants: molecular interactions, assembly, and applications, Surf. Sci. Rep. 72 (1) (2017) 1 58. [26] S.S. Ray, A.O.C. Iroegbu, Nanocellulosics: benign, sustainable, and ubiquitous biomaterials for water remediation, ACS Omega 6 (7) (2021) 4511 4526. ˙ [27] I.V. Ferna´ndez, K. Druzbicki, F.F. Alonso, S. Mukhopadhyay, P. Nockemann, S.F. Parker, et al., Spectroscopic signatures of hydrogen-bonding motifs in protonic ionic liquid systems: insights from diethylammonium nitrate in the solid state, J. Phys. Chem. C 125 (44) (2021) 24463 24476. [28] P. Isosaari, V. Srivastava, M. Sillanpa¨a¨, Ionic liquid-based water treatment technologies for organic pollutants: current status and future prospects of ionic liquid mediated technologies, Sci. Total Environ. 690 (2019) 604 619. [29] K.S. Khoo, H.Y. Leong, K. Wayne, J.W. Lim, T.C. Ling, P.L. Show, et al., Liquid biphasic system: a recent bioseparation technology, Processes 8 (2) (2020) 149. [30] G.T. Wei, Z.S. Yang, C.J. Chen, Room temperature ionic liquid as a novel medium for liquid/liquid extraction of metal ions, Anal. Chim. Acta 488 (2003) 183 192. [31] N.H. Solangi, A. Anjum, F.A. Tanjung, S.A. Mazari, N.M. Mubarak, A review of recent trends and emerging perspectives of ionic liquid membranes for CO2 separation, J. Environ. Chem. Eng. 9 (2021) 105860. [32] S. Kalidhasan, A.S.K. Kumar, V. Rajesh, N. Rajesh, Enhanced adsorption of hexavalent chromium arising out of an admirable interaction between a synthetic polymer and an ionic liquid, Chem. Eng. J. 222 (2013) 454 463. [33] A. Nasrollahpour, S. Moradi, S. Moradi, Dispersive solid phase micro-extraction of mercury (II) from environmental water and vegetable samples with ionic liquid modified graphene oxide nanoparticles, J. Serb. Chem. Soc. 82 (2017) 551 565. [34] E. Bazrafshan, A.A. Zarei, L. Mohammadi, M.N. Zafar, M. Foroughi, S. Aman, et al., Efficient tetracycline removal from aqueous solutions using ionic liquid modified magnetic activated carbon (IL@mAC), J. Environ. Chem. Eng. 9 (2021) 106570. [35] M.O. Simon, C.J. Li, Green chemistry oriented organic synthesis in water, Chem. Soc. Rev. 41 (2012) 1415 1427. [36] W. Dai, S.J. Geib, D.P. Curran, 1,4-Hydroboration reactions of electron-poor aromatic rings by N-heterocyclic carbene boranes, J. Am. Chem. Soc. 1142 (13) (2020) 6261 6267. [37] S. Sen, S. Hufnagel, E.Y. Maier, I. Aguilar, J. Selvakumar, J.E.D. Vore, et al., Rationally designed redox-active Au(I) N-heterocyclic carbene: an immunogenic cell death inducer, J. Am. Chem. Soc. 142 (49) (2020) 20536 20541. [38] E.M. Phillips, A. Chan, Karl A. Scheidt, Discovering new reactions with N-heterocyclic carbene catalysis, Aldrichim. Acta 42 (3) (2009) 55 66.

Green Chemistry Approaches to Environmental Sustainability

90

4. Application of green chemistry for environmental remediation

[39] P.A. Schulte, L.T.M. Kernan, D.S. Heidel, A.H. Okun, G.S. Dotson, T.J. Lentz, et al., Occupational safety and health, green chemistry, and sustainability: a review of areas of convergence, Env. Health 12 (31) (2013). Available from: https://doi.org/10.1186/1476-069X-12-31. [40] A.D.V. Kreuder, T.H. Knight, J. Whitford, E. Ponnusamy, P. Miller, N. Jesse, et al., A method for assessing greener alternatives between chemical products following the 12 principles of green chemistry, ACS Sustain. Chem. Eng. 5 (4) (2017) 2927 2935. [41] M. Poliakoff, W. Leitner, E.S. Streng, The twelve principles of CO2, Faraday Discuss. 183 (2015) 9 17. [42] P. Anastas, N. Eghbali, Green chemistry: principles and practice, Chem. Soc. Rev. 39 (2010) 301 312. [43] S.A.M.Tofail, E.P. Koumoulos, A. Bandyopadhyay, S. Bose, L. Donoghue, C. Charitidis, Additive manufacturing: scientific and technological challenges, market uptake and opportunities, materialstoday, 21, 1, 2018, 22 37. [44] J. Amouroux, P. Siffert, J.P. Massue´, S. Cavadias, B. Trujillo, K. Hashimoto, et al., Carbon dioxide: a new material for energy storage Progress in Natural Science, Mater. Int. 24 (4) (2014) 295 304. [45] D.J.C. Constable, Green and sustainable chemistry the case for a systems-based, interdisciplinary approach, iScience 24 (12) (2021) 103489. Available from: https://doi.org/10.1016/j.isci.2021.103489. [46] J.M. Cooper, Introduction. The Asia Pacific World: A Summary and an Agenda J.S. Eades and Malcolm, Asia Pacific World 1(1), Spring 2010: 1 22. [47] R. Kandimalla, J. Vallamkondu, E.B. Corgiat, K.D. Gill, Understanding aspects of aluminum exposure in Alzheimer’s disease, Dev. Brain Pathol. 26 (2) (2016) 139 154. [48] P. Rajasulochana, V. Preethy, Comparison on efficiency of various techniques in treatment of waste and sewage water a comprehensive review, Resource-Efficient Technol. 2 (4) (2016) 175 184. [49] J. Colberg, K.K. (Mimi), Hii, S.G. Koenig, Importance of green and sustainable chemistry in the chemical industry, ACS Sustain. Chem. Eng. 10 (26) (2022) 8239 8241. [50] P.G. Jessop, F. Ahmadpour, M.A. Buczynski, T.J. Burns, N.B. Green, R. Korwin, et al., Opportunities for greener alternatives in chemical formulations, Green. Chem. 17 (2015) 2664 2678. [51] N. Evode, S.A. Qamar, M. Bilal, D. Barcelo´, H.M.N. Iqbal, Plastic waste and its management strategies for environmental sustainability, Case Stud. Chem. Environ. Eng. 4 (2021) 100142. [52] L. Mammino, CHAPTER 1: A great challenge of green chemistry education: the interface between provision of information and behaviour patterns, in Worldwide Trends in Green Chemistry Education, 2015, 1 15. Available from: https://doi.org/10.1039/9781782621942-00001; eISBN: 978-1-78262-194-2. [53] M.D. L. Guardia and S. Garrigues, Chapter 1:Past, Present and Future of Green Analytical Chemistry, in Challenges in Green Analytical Chemistry (2), 2020, 1 18. Available from: https://doi.org/10.1039/9781788016148-00001. [54] M. Kaur, K.S. Sandhu, J. Kaur, Pasting properties of Tamarind (Tamarindus indica) kernel powder in the presence of Xanthan, Carboxymethylcellulose and Locust bean gum in comparison to Rice and Potato flour, J. Food Sci. Technol. 50 (4) (2013) 809 814. [55] S. Samanta, V.K. Rangasami, N.A. Murugan, V.S. Parihar, O.P. Varghese, O.P. Oommen, An unexpected role of an extra phenolic hydroxyl on the chemical reactivity and bioactivity of catechol or gallol modified hyaluronic acid hydrogels, Polym. Chem. 12 (2021) 2987 2991. ˇ [56] A. Buˇsi´c, N. Marðetko, S. Kundas, G. Morzak, H. Belskaya, M.I. Santek, et al., Bioethanol production from renewable raw materials and its separation and purification: a review, Food Technol. Biotechnol. 56 (3) (2018) 289 311. [57] A.A.F. Husain, W. Zuha, W. Hasan, S. Shafie, M.N. Hamidon, S.S. Pandey, A review of transparent solar photovoltaic technologies, Renew. Sustain. Energy Rev. 94 (2018) 779 791. [58] R. Kumar, A. Verma, A. Shome, et al., Impacts of plastic pollution on ecosystem services, sustainable development goals, and need to focus on circular economy and policy interventions, Sustainability 13 (17) (2021) 9963. [59] H. Cui, X. Huang, Z. Yu, P. Chen, X. Cao, Application progress of enhanced coagulation in water treatment, RSC Adv. 10 (2020) 20231 22024. [60] S. Palit and C.M. Hussain, Chapter 1: Innovation in environmental remediation methods, in The Handbook of Environmental Remediation: Classic and Modern Techniques, 2020, Royal Society of Chemistry. pp. 1 23, Available from: https://doi.org/10.1039/9781788016261-00001. [61] M. Wei, B. Wang, M. Chen, H. Lyu, X. Lee, S. Wang, et al., Recent advances in the treatment of contaminated soils by ball milling technology: classification, mechanisms, and applications, J. Clean. Prod. 340 (2022) 130821. [62] M.N.F. Norrrahim, N.A.M. Kasim, V.F. Knight, M.S.M. Misenan, N. Janudin, N.A.A. Shah, et al., Nanocellulose: a bioadsorbent for chemical contaminant remediation, RSC Adv. 11 (2021) 7347 7368.

Green Chemistry Approaches to Environmental Sustainability

References

91

[63] C.S. Eckley, C.C. Gilmour, S. Janssen, T.P. Luxton, P.M. Randall, L. Whalin, et al., The assessment and remediation of mercury contaminated sites: a review of current approaches, Sci. Total Environ. 10 (707) (2020) 136031. Available from: https://doi.org/10.1016/j.scitotenv.2019.136031. [64] N.N. Solihat, T. Acter, D. Kim, A.F. Plante, S. Kim, Analyzing solid-phase natural organic matter using laser desorption ionization ultrahigh resolution mass spectrometry, Anal. Chem. 91 (1) (2019) 951 957. [65] M. Bui, C.S. Adjiman, A. Bardow, E.J. Anthony, A. Boston, S. Brown, et al., Carbon capture and storage (CCS): the way forward, Energy Environ. Sci. 11 (2018) 1062 1176. [66] J. Gesels, F. Dolle´, J. Leclercq, A. Jurado, S. Brouye`re, Groundwater quality changes in peri-urban areas of the Walloon region of Belgium, J. Contaminant Hydrol. 240 (2021) 103780. [67] L. Rani, K. Thapa, N. Kanojia, N. Sharma, S. Singh, A.S. Grewala, et al., An extensive review on the consequences of chemical pesticides on human health and environment, J. Clean. Prod. 283 (2021) 124657. [68] D. Cecconet, F. Sabba, M. Devecseri, A. Callegari, A.G. Capodaglio, In situ groundwater remediation with bioelectrochemical systems: A critical review and future perspectives, Environ. Int. 137 (2020) 105550. [69] L. Wei, H. Bu, Y. Wei, H. Wu, G. Wang, P. Chen, et al., Fractionation of natural algal organic matter and its preservation on the surfaces of clay minerals, Appl. Clay Sci. 213 (2021) 106235. [70] J.K. Komosinska, A. Dzieniszewska, W. Franus, G. Rzepa, Behavior of Ag species in presence of aquatic sediment minerals in context of aquatic environmental safety, J. Contaminant Hydrol. 232 (2020) 103606. [71] S. Wyke and R.D. Davidson, CHAPTER 1:Overview of alerting, assessing and responding to chemical public health threats, in Chemical Health Threats: Assessing and Alerting, 2018, Royal Society of Chemistry, 1 23. Available from: https://doi.org/10.1039/9781782623687-00001. [72] J. Luo, S. Zhang, M. Sun, L. Yang, S. Luo, J.C. Crittenden, A critical review on energy conversion and environmental remediation of photocatalysts with remodeling crystal lattice, surface, and interface, ACS Nano 13 (9) (2019) 9811 9840. [73] A. Bianchini, F. Cento, A. Guzzini, M. Pellegrini, C. Saccani, Sediment management in coastal infrastructures: techno-economic and environmental impact assessment of alternative technologies to dredging, J. Environ. Manag. 248 (2019) 109332. [74] S.D. Gisi, G. Lofrano, M. Grassi, M. Notarnicola, Characteristics and adsorption capacities of low-cost sorbents for wastewater treatment: a review, Sustain. Mater. Technol. 9 (2016) 10 40. [75] C.J. Miller, M.R. Morris, A.E.C. Bushrow, J.K. Straughen, T.M. Dittrich, T.R. Baker, et al., A review of volatile organic compound contamination in post-industrial urban centers: reproductive health implications using a Detroit lens, Int. J. Env. Res. Public Health 17 (23) (2020) 8755. [76] P. Sharma, K. Kostarelos, S. Lenschow, A. Christensen, P.C. de Blanc, Surfactant flooding makes a comeback: results of a full-scale, field implementation to recover mobilized NAPL, J. Contam. Hydrol. 230 (2020) 103602. Available from: https://doi.org/10.1016/j.jconhyd.2020.103602. [77] P. Marchetti, M.F.J. Solomon, G. Szekel, A.G. Livingston, Molecular separation with organic solvent nanofiltration: a critical review, Chem. Rev. 114 (21) (2014) 10735 10806. [78] D.Y.C. Leung, G. Caramanna, M.M.M. Valer, An overview of current status of carbon dioxide capture and storage technologies, Renew. Sustain. Energy Rev. 39 (2014) 426 443. [79] J. Lee, U.V. Gunten, J.H. Kim, Persulfate-based advanced oxidation: critical assessment of opportunities and roadblocks, Environ. Sci. Technol. 54 (6) (2020) 3064 3081. [80] C. Labianca, S.D. Gisi, F. Picardi, F. Todaro, M. Notarnicola, Remediation of a petroleum hydrocarboncontaminated site by soil vapor extraction: a full-scale case study, Appl. Sci. 10 (12) (2020) 4261. Available from: https://doi.org/10.3390/app10124261. [81] D. Jiang, G. Zeng, D. Huang, M. Chen, C. Zhang, C. Huang, et al., Remediation of contaminated soils by enhanced nanoscale zero valent iron, Environ. Res. 163 (2018) 217 227. [82] C.C. Azubuike, C.B. Chikere, G.C. Okpokwasili, Bioremediation techniques classification based on site of application: principles, advantages, limitations and prospects, World J. Microbiol. Biotechnol. 32 (11) (2016) 180. Available from: https://doi.org/10.1007/s11274-016-2137-x. [83] A. Agarwal, Y. Zhou, Y. Liu, Remediation of oil-contaminated sand with self-collapsing air microbubbles, Env. Sci. Pollut. Res. Int. 23 (23) (2016) 23876 23883. Available from: https://doi.org/10.1007/s11356-0167601-5.

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C H A P T E R

5 Approaches and challenges with respect to green chemistry in industries Suneeta Bhandari1, Akansha Agrwal2 and Munni Bhandari3 1

Organic Synthesis Laboratory, Department of Chemistry, G. B. Pant University of Agriculture and Technology, U.S. Nagar, Uttarakhand, India 2Department of Applied Sciences, KIET Group of Institutions, Delhi-NCR, Ghaziabad, Uttar Pradesh, India 3Department of Microbiology, H.N.B. Garhwal University, Srinagar Garhwal, Uttarakhand, India

5.1 Introduction The worldwide industry has grown tremendously during the 20th century, and lifestyles in industrialized nations have been steadily increased. With the world’s economy becoming more challenging and raw materials on the earth becoming increasingly scarce, it is essential to minimize both energy consumption and waste generation. One prominent trend that has emerged is sustainability, which allows science and technology organizations to engage that focus on the benefits and health of the consumer in a clean and sustainable environment [1]. People that work in research and development endure a slew of truly innovative challenges, since its green synthesis breakthrough. Though such failures, there is still a comparable possibility to build for using new chemistry, enhancing the overall economic growth of chemical production, and rebuilding chemistry’s damaged reputation [2]. Environmental and sustainable development concerns are gradually becoming very prominent aspects of design and manufacturing development [3]. Emerging raw material, commercial, ecological as well as environmental concerns will necessitate highly proficient, integrated chemistry and manufacturing technology. Green chemistry can solve many such obstacles by expanding the definition of its operations to maximize the desired materials while reducing the technology needed for producing safe and sustainable compounds that are intrinsically, environmentally sustainable and energyefficient [4].

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Green chemistry revolution provides several challenges to chemists, academic researchers and scientific studies [2]. Green chemistry aimed to create better, ecofriendly products by opting for the safest, more productive way to manufacture them, minimizing waste and preventing risk from the initial stage [5]. With these limitations, new opportunities emerge to develop and propose innovative chemistry, enhance chemical production efficiency, and rebuild chemistry’s compromised appearance [6]. All these will be discussed in this chapter.

5.2 Green chemistry’s impact Research provided mostly by EPA’s Toxics Release Inventory (TRI) reveals that from 2004 to 2013, lower chemical pollutants were discharged into the environment on soil, within the atmosphere and even in the water. Such results demonstrate an ever more around 60% reduction of various toxic emissions beyond this duration, especially methyl isobutyl ketone, trichloroethylene and hydrochloric acid. Its pharmaceutical sector, which has historically produced the maximum toxic waste for each kilogram of product to make complex organic compounds of high value, has seen a reduction of nearly 50% in its documented toxic waste discharges. The majority of such development, according to an EPA study, is the result of green design as well as chemistry techniques [7].

5.3 History of green chemistry It is indeed a revolutionary chemical science concerned with the use of environment friendly chemicals in numerous aspects of our lives, including industrial applications and so on. The basic requirement for avoiding the hazardous risks both physical and chemical materials caused to living creatures prompted the creation of this field of chemistry. Several chemical substances, either found in nature or generated within the laboratory, possess unfavourable impacts on human health, irrespective of their commercial value. Organic chemicals seem to be particularly noteworthy since they can effortlessly penetrate the hydrophobic cell membrane and spread throughout the body.

5.3.1 Green chemistry The paradigm of “green chemistry” appears distinct throughout the production, processing as well as utilization of various chemicals that avoid risks to the environment. Paul Anastas from Yale University, the founder of green chemistry, said their objective is to create such products as well as procedures that reduce or do away with production through the use of harmful toxins [8]. The Pollution Prevention Act of 1990, which has been managed to pass during this decade, marked a shift in regulatory reform from reducing pollution to pollution preventative measures as being the most efficient method of addressing several other environmental aspects. The 1990s have always been the era that saw the establishment of the sustainable development field [9].

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The revolutionary book Green Chemistry: Theory and Practice by Paul Anastas and John C. Warner was published in 1998 [10]. The concept presented in this book’s “12 Principles of Green Chemistry” inspired both academic and industrial chemists simultaneously while remaining somehow at the core of the revolution. Green chemistry refers to the innovation, creation, development, as well as utilization of chemical products and procedures to eliminate or reduce toxic chemicals to minimize the hazardous exposure to people and the natural environment [11]. Diverse green techniques are being used to treat wastewater, produce energy and build technology, medications, polymers and chemicals, among other products [12].

5.3.2 Twelve principles of green chemistry In 1998, Paul Anastas and John C. Warner put forth the 12 tenets of green chemistry. Fig. 5.1 contains a schematic that illustrates the 12 tenets of green chemistry [13]. It begins at its basic level and subsequently identifies its most significant operations producing products that are sustainable and ecofriendly. Several group prominent chemists discussed the impacts of industrial and commercial processes on earth’s atmosphere during the IUPAC CHEMRAWN XIV Conference on Green Chemistry: Towards Environmentally Benign Processes and Products, which was held in 2001 at the University of Colorado, Boulder. Researchers recommended using a “design-for-environment” approach to cooperate among users and improve the reliability of goods and products created using green techniques for sustainable agriculture practice [14]. The elimination or minimization of toxic chemicals from production is addressed by key principles of green chemistry. As a result, it becomes less or more unlikely to utilize

FIGURE 5.1 The 12 principles of green chemistry.

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harmful compounds for both the social environment and the ecosystem. It is not feasible to include all of the concept’s criteria in the development of a green chemistry procedure at once, although initiatives to use it are made during specific phases of synthesis [15 19]. The following benefits of using greener chemistry techniques, in particular, are listed for the 12 green chemistry principles: 1. Minimization of waste; the majority of solvents and reagents may be recycled, which can prevent waste and emissions of producing organic compounds; 2. keeping the loss of precursors and intermediate compounds to a minimum while the final material is being synthesized would maximize the economy of matter (atoms); 3. chemical processes with a lower risk that use relatively safe and nontoxic chemicals; 4. minimal as well as reliable solvents and separating reagents, including natural resources such as water natural compounds; 5. the use of alternative energy sources, with optimal circumstances being normal pressure as well as room temperature, and thus the reduction of energy consumption; 6. reducing the number of chemical substances used (fewer chemical steps or even additional compounds) to reduce waste; 7. the utilization of several effective catalysts, which increases product output; the usage of substances that degrade naturally and have no negative environmental consequences; 8. contamination control by continuous (real-time) monitoring of process phases, if feasible; 9. modest amounts of reactant molecules to avoid mishaps (fire, explosives, leaks); 10. green procedures are more affordable and efficient, frequently producing higherquality goods; and 11. green practices facilitate minimizing issues regarding numerous environmental policies.

5.4 Challenges for chemists Researchers, chemists and others have been constantly challenged with the concept of making new goods and procedures, including applications that can provide the socioeconomic and environmental needs that are now envisaged in synthetic chemistry. This introduces a particular strategy that reduces synthetic processes and products resulting from energy requirements and considerably decreases harmful chemical spread across the climate, increases usage of renewable resources, and maximizes reliability and reusability. Scientists are facing issues concerning green synthesis techniques, such as the novel and environmentally friendly solvents, efficient and environmentally benign catalysis in synthetic chemistry, dry composite synthesis, catalyst-free procedures in synthesis, together with ecologically responsible output. To accomplish social, economic and climatic goals, environmental sustainability is recognized worldwide by authorities, organizations, as well as the general public as a vital objective. Under this, chemistry plays a crucial role in preserving and enhancing the overall standard of health, the efficiency of the chemical sector, as well as the sustainability of

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the environment. In comparison to oil, gas, power, paper and pulp sectors, chemical marketing is constantly viewed as relatively less favourable. Challenges regarding the adverse effect on the environment, transportation, security as well as trash are indeed the primary justifications provided for negative perceptions upon the chemical sector. Massive amounts of garbage are being generated as a consequence of such production methods, and even the organization, government and broader population are all now focused on reducing or eliminating these wastages. Introducing new goods and procedures, including facilities that deliver significant ethical, economical or even high relevance currently demanded, seems to be a task confronting research scientists. The above urges for a novel strategy here that seeks to improve productivity along with competitive nature by decreasing the raw material and output severity of synthetic practices as well as goods, reducing or trying to minimize the consumption of nonrenewable resources, avoiding the emission of dangerous contaminants throughout the environment, driving product endurance and enhancing product recycling. The implementation of novel synthesis employing substitute compounds or several specific chemicals, the revelation of distinct experimental conditions as well as a solvent based for upgraded specificity or energy cost reduction, and indeed the layout with less noxious and essentially hygienic substances are among the issues facing chemists today. The progression of “green chemistry” is yet hampered by numerous obstacles, despite the tireless efforts of several researchers as well as business groups. The industrial sector would also need to innovate and create new techniques that have not been seen across several years to ensure the push forward into cleaner technology has resulted in an emphasis on reducing the amount of waste generated. Recent societies, where people are more concerned about climate change, would make established chemical reactions that frequently rely on technologies created during the initial half of the 20th century unacceptable. Another new generation of goods and procedures would be driven by “alternative energy”.

5.5 Application of green chemistry in industry The medicinal industry stands to benefit from green synthetic implementations and cutting-edge techniques that greatly reduce or eliminate the usage of organic solvents or otherwise improve their safety and efficacy. A rising variety of techniques to manufacture conventional petroleum-based compounds using biomaterials, frequently plant products or garbage have also been influenced by green chemistry. In the development of innovative processes for making solar cells, battery storage or battery chargers for energy storage, green chemistry is indeed extremely important.

5.6 Greener pharmaceutical industries One of the very first industries to appreciate the benefits of green chemistry was the pharmaceutical sector. Since 1996, 11 Presidential Green Chemistry Awards have been given in recognition of procedures created by or for the pharmaceutical industry [20]. Fig. 5.2 shows the benefits of green chemistry in the industry.

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FIGURE 5.2 The benefits of green chemistry in the industry.

The majority of production is being done by pharmaceutical industries. It is leading the way in significant transitions to “greener” feedstock, cleaner solvents, alternative techniques and innovative solutions. Most of these changes will raise pharmaceutical industries’ ecological existence while also reducing expenditures and material requirements for manufacturing processes, moving the industry closer to sustainability [21 24]. Green chemistry concepts can be used in the pharma industry as either responsibility or a significant opportunity to enhance our beneficial impact on the world’s population. Letermovir, an antiviral medicine (cytomegalovirus infection) that is in phase III for its clinical trials nowadays, was successfully synthesized by the US-based Merck & Co., Inc. through green chemistry perception. Common viral cytomegalovirus (CMV) infections typically have no symptoms in normal individuals and can have serious consequences for people with immunosuppressed systems. Since it has been given an Orphan Product label by Fast-Track status & European Medicine Agency by FDA also for the treatment of CMV viremia among people at high risk, it is indeed possible to assess the significance of such a medication [1]. In comparison to the previous approach, a new greener formulation for ibuprofen introduced by BASF merely requires half as many steps. Atom efficiency for this new method is nearly two times that of the previous synthesis. Bi-phasic Acid Scavenging Utilizing Ionic Liquids, or BASILTM, is a procedure that BASF designed to produce the general photoinitiator precursor alkoxy phenyl phosphine [25]. This approach was implemented to establish sustainable approaches. The yield grew by 98% with the help of this technique. The popular medication Viagra, generally referred to by one of its generic name’s sildenafil citrates, served as Pfizer’s “poster child” because of its commitment to environmental

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sustainability. Since managing to generate Viagra about the market, Pfizer’s research scientists devised a novel reaction approach that substantially decreased the quantity of solvent needed, effectively removed the reagent’s tin chloride (an environmental risk) as well as hydrogen peroxide (an extinguisher and transit fire risk), but instead generated only 25% of squandering of an initial process [26]. Additionally, Pfizer recently enhanced the method used to create its very well Lipitor (atorvastatin), a medication therapy lowering blood cholesterol, by ensuring that it makes use of an enzyme that catalyzed the biochemical processes into the aqueous medium, decreasing a requirement for potential. Zocor (simvastatin), other popular medication for lowering cholesterol, was formerly manufactured using a series of sequential steps utilizing significant quantities of risky chemicals that resulted in a substantial number of risky effluents. According to the American Chemical Society’s “Explanations of Green Chemistry”, a novel approach to making the medication employs an engineered enzyme and a cheap material that Codexis, a biocatalysis business, improved [27,28]. Its active component of Januvia, a medication for type 2 diabetes, sitagliptin, was also developed by Codexis and Merck using a greener method of synthesis. As a result of this partnership, an enzymatic method has been created that decreases wastage, boosts productivity as well as efficiency, and does away with the requirement for a metal catalyst [29]. Paclitaxel, a chemotherapeutic medicine, is indeed prominent medicine with very little waste generated presently (marketed as Taxol). The first method of making it involved isolating compounds from the bark of yew trees, a procedure that killed the tree and necessitated a large amount of additional solvent. These days, medicine is created by allowing tree cells to grow in a fermentation vat [30].

5.7 Greener solvents The usage of additional compounds, which include solvents, “should have been made unnecessary and where ever feasible and benign when employed”, according to the fifth green chemistry principle [31]. When it comes to promoting green chemistry, solvents are indeed a foremost objective although they are regularly being used and usually involve volatile organic chemicals, which increases the risk of hazardous gas production, environmental pollution and certain other health problems. One of its best methods to improve both the efficacy and safety of either a process or product should be to find safer, better effective substitutes or eliminate solvents [31]. The bleaching of fabrics seems to be a prominent example of a green solvent that is currently in commercial use. Since the dyed cloth needs to first be dried, conventional dyeing consumes a significant amount of work and demands a huge amount of water 7 gallons to bleach a T-shirt. The Dutch-based DyeCoo company is the introductory company who invented textile dyeing in industries, a water-free dying procedure associated with apparatus that uses carbon dioxide at supercritical pressure, which functions like a solvent when under pressure and at slightly elevated temperature [20]. Manufacturers of cleaning agents, aerosol cleaners, and certain other cleaning materials for such households and workplaces have recently included greener liquids to enhance their effectiveness towards the benefit of both the environment and human impacts. Tide

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Coldwater Clean will employ cellulosic ethanol made by corncobs and stalks, according to plans revealed by Procter & Gamble and DuPont. DuPont can substitute ethanol generated from corn kernels with cellulosic ethanol either from a plant it is developing in Iowa. The partners claim that by incorporating Tide Coldwater with such cellulosic ethanol, over 7000 tonnes of agrowaste is being recycled by their residues yearly while also saving enough energy for washing clothes at California in all homes for a month [32]. 1,3Propanediol, a different bio-based molecule that DuPont provides for sale, functions like an enzyme transporter, solvent and stabilizer. Ecologically responsible system trademark household products, such as an aerosol cleaner and then a powerful laundry detergent, include propanediol [32]. Butyl 3-hydroxybutyrate, popularly known as Omnia, seems to be another ecofriendly cleaning agent that has been developed by Eastman Chemical. Mostly with the assistance of computer-based simulations or even wet-lab experimentation, Eastman simplified a catalogue of almost 3000 compounds with potential as cleaning agents to just one to generate the novel solvent [32]. Earlier this year, a group at the University of Wisconsin at Madison reported an promising bio-based greener solvent [33]. Researchers converted biomass made of hemicellulose and cellulose producing high-value platform compounds as well as vehicle fuel using mineral acid catalysts as a solvent. The procedure (which was performed in a biphasic system) included solutions made from lignin that reduced secondary reactions inside the aqueous solutions, thus allowing the mineral acid catalysts to be recycled [34]. Among chemists, a novel approach for avoiding solvents that include acetonitrile distilled alcohols mixed with other substances could be utilized as a replacement in highperformance hplc analysis (HPLC) [35]. However, according to recent studies by some experts at Merck Research Laboratories, the above blending can often yield good analytical findings while being a reliable and cost-effective substitute eluent for HPLC [36]. Water, supercritical carbon dioxide, and ionic liquids are some other greener solvents that are being used more frequently [37]. An increasingly different type of certain other methods to synthesize chemicals that are typically generated through petroleum or several other nonrenewable substances has already been developed, with a major contribution coming through green chemistry.

5.8 Bio-based modifications and resources A bio-based procedure that is nowadays conveniently obtainable in 2003, the Sorona polymer from DuPont, received a Presidential Green Chemistry Accolade. This method was created by DuPont that replaces petroleum with regenerated corn starch as well as a genetically modified microbe to produce cost-effective fabrics [37]. Clothing, flooring or even packaging also can be made with the Sorona polymer. Comparing such a bio-based approach with conventional petrochemical methods, it consumes less energy, emits fewer pollutants and makes use of sustainable resources [38]. Employing a method created at Genomatica that achieved a certain application, BASF is now economically generating reusable 1,4-butanediol, which was recognized with the reward of the 2011 Presidential Green Chemistry Challenge from the EPA for “Greener

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Synthetic Pathways” (1,4-BDO) [39]. This biomaterial is employed to generate BASF’s Ecoflex recyclable polyester film, which is later combined with calcium carbonate and cassava starch to generate entirely biodegradable Ecovio bags. These Biodegradable Products Institute-certified bags decompose in commercial composting systems into water, CO2 and biomass [28]. The scientists were responsible for creating 2,4-pentanedione, commonly referred to as acetylacetone, which has some industrial uses, such as removing heavy metals, electroplating and even as a fuel additive. Additionally, scientists changed it into dienoic acid, which is often made from petrochemical sources that become beneficial as an additive in food products since it can prevent the spread of different fungi and bacteria. Hexenoic acid, a substance that has the potential to be a flavour, and γ-caprolactone component for aromatherapy as well as cosmetics, are two other chemicals that researchers claimed to have produced and employed the green synthesis of these compounds [40]. Another example is the method utilized by LanzaTech, a company based in Auckland, New Zealand, to use microbial fermentation to turn carbon monoxide-containing gases into ethanol and other compounds. Because most steel companies produce carbon monogaseous discharges, LanzaTech constructed a 100,000-gallon annual ethanol production pilot plant at Baosteel, the biggest steel producer in China, in Shanghai. Additionally, the microorganisms used by LanzaTech are capable of producing 2,3-butanediol, which may then be transformed into other substances including synthetic rubber generated through using monomer 1,3-butadiene [40]. Coskata, situated in the United States, is a different business that promotes hybrid chemical processing technologies. By thermochemically gasifying biomass or other solid materials or by catalzing the reformation of natural gas, Coskata creates syngas, a combination primarily composed of CO and hydrogen. Lowmolecular-weight alcohols are produced via the selective microbiological fermentation of syngas. A combination of wood chippings as well as many thousands of litres of ethanol can also be produced annually at a plant run by Coskata [40]. Microalgae are engineered by that same biotech firm Solazyme in California to generate substantially more oil than the 5% 10% found in naturally occurring algae. The business received the 2003 Greener Synthetic Pathways Award from the Presidential Green Chemistry Challenge, which was given out in 2014. Its outputs have included the industrial manufacture of fatty acids, and palm kernel oil, which contains the compounds C10 and C12 and are chemically comparable to the algal oils produced commercially. A laundry detergent, made by the Belgian company Ecover, for example, contains the company’s oils [41]. Solazyme and Myriant are two further famous corporations that manufacture bio-based compounds. Premised in Massachusetts, Myriant creates biobased drop-in alternatives and equivalents towards a broad range of petroleum-based chemicals, such as succinic acid, that are utilized in pigments, medicines, as well as metal plating and possesses a multibillion-dollar global industry [42].

5.9 Green synthesis To completely utilize the possibilities of renewable energy sources, green chemistry encourages the emergence of technological innovations. Green synthesis emphasizes

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exploring methods to create things using sustainable and biocompatible materials, like plants and agricultural waste, while previously many of the ingredients used to generate products have been frequently harmful or exhausted significant sources, including certain petroleum. For instance, approximately 80% of biomass that is composed of cellulose and hemicellulose can also be converted to sugars, which can subsequently be fermented to produce chemicals like alcohol, organic acids, propylene glycol and aldehydes. The innovation of such a novel class of genetically enhanced bacteria that can break down the various sugars in hemicellulose and others has made the conversion of biomass into ethanol both scientifically and economically feasible [5]. Levulinic acid frequently produced from biomass via a company named Segetis, established in the United States, distributes levulinic ketal-based components for personal regular cleaning goods and operates a pilot-scale microbially levulinic acid in Minnesota. Recently, efforts to produce levulinic acid through bioenergy were launched by different chemical firms in Italy. These companies assert that their developments will reduce prices or rather turn specialty chemicals intodesirable new materials for products applicable for protection of crop, lubricants and fuel sources. Levulinic acid is quite demanding to develop being traditionally produced via maleic anhydride, restricting its need for lowvolume usage like cosmetics and food products [43].

5.10 Alternative renewable energy science 5.10.1 Photovoltaic solar energy A recent report claims that perovskite solar cells innovation represents unprecedentedly very sustainable, decarbonized resources possessing the pair of adaptability as well as the technical proficiency to supply ever-increasing worldwide consumption of electricity [44]. Since 2000, global utilization of solar photovoltaic panels has continued to rise by 43% annually. The advent of innovative new science based on photovoltaics, perovskite solar cells incorporating quantum dots, has recently generated a lot of excitement among green renewable energy researchers. Due to their high-power yields using inexpensive substances which are comparatively easy to transform into functional devices, perovskite solar cells perform better than the majority of more established photovoltaic techniques. The word “perovskite” refers to one mineral that was first identified in the past that is primarily made up of calcium titanate (CaTiO3). These days, scientists are using the term broadly to describe a significant family of substances that, such as CaTiO3, possess ABX3 stoichiometric ratio and utilize the perovskite crystal structure. Organometaltrihalides, the most commonly studied of which is CH3 NH3 PbI3, are indeed the perovskites that have been currently attracting much more concern for the photovoltaics industry. The A group in ABX3 is CH3 NH3, for example. The efficiency of Perovskite solar devices has recently improved at an extremely high rate, which is a significant determinant of enthusiasm [45]. Through standard wet-chemistry methods, perovskite solar cells can indeed be created. In the future, solar-cell producers could be able to create photovoltaics without clean rooms or advanced industrial machinery by using straightforward benchtop procedures to

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continue making the elements of solar cells through liquid-phase chemical reactions and depositing the substances using techniques like spraying and spin coating [45]. The year 2013 saw the rapid publication of several research papers on various journal websites, each of which described a considerably distinct perovskite-structured compound, architecture, with detailed advancement in competencies. The National Renewable Energies Laboratory, which is regarded internationally as the official supervisor for photovoltaic-based energy performance, has indeed verified the efficacy of each optimized design. Perovskite needs to be produced by low-temperature technique, utilizing a revolutionary process to produce greater effectiveness, resonant, consistent photovoltaic materials which can be bonded over windows or painted on walls, according to research from the United Kingdom that was published in March 2015 [46,47]. 5.10.1.1 Quantum dots Nanocrystals of semiconductor materials, or “quantum dots”, are activated with light or an applied voltage to create a brilliant illumination of a single colour [48]. Although solar panels based on quantum dots get the possible efficiency of about 45%, several alternative energy experts are enthusiastic about them. This is possible since a single photon’s absorption by a quantum dot results in the production of many bound exciton pairs, which double the typical conversion efficiency figures observed in single-junction silicon cells [49]. Although the costs are growing, so far no one has possibly attempted to achieve a certain degree of persuasiveness. For illustration, researchers in 2014 reported how quantum-dot solar cells using ternary CuInS2 created a new benchmark of 7.04% (with certified efficiency of 6.66%) [50]. The efficient sequence of greener catalysts designed by Terry Collins from Carnegie Mellon University, based upon naturally occurring peroxidase enzymes, has the potency to minimize the environmental effect of the pharmaceutical sector [51]. Collins believes this just incorporating such catalysts into the treatment of wastewater at a later stage will be sufficient to split down many chemical wastes, such as from Lipitor, Prozac, Zoloft, other medications, and much more, once they are released into the atmosphere [52 54]. 5.10.1.2 Fuel cells Over the past 10 years, costs of fuel cells have declined; their vehicle mobility has increased, while experts have improved their potential to work in severe climatic conditions as well as in adverse circumstances [55]. The very first fuel-cell automobiles come to market in the United States in 2015, while scientists and engineers are still working to develop the technology behind the batteries used to generate electricity by combining hydrogen and oxygen with water. A Boston College research group recently developed a chemical that stores H2 but disintegrates steadily at high temperature of 150 C. Scientists have created a brand-new substance known as bis-BN cyclohexane which may be useful for many purposes like emergency generators that could also conserve electricity for a long time throughout times of emergency. Scientists discovered that it functions as either an efficient and stable catalytic system in alkaline and acidic fluids throughout the specified range of fuel-cell voltages by using palladium-silver nanoparticles based upon the high porosity of Ti0.5Cr0.5 N network.

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Analysis revealed that the substance was even more robust and energetic than typical carbon materials. 5.10.1.3 Sustainable energy storage Since these may enable the optimal utilization of the energy generated by renewable sources, sustainable energy-storage techniques become crucial. Imitating nature and its rich biodiversity is becoming more and more common in energy storage and modification systems [56]. Besides looking at the image from living chemistry, which would be driven through chemical reactions which then rely on ion flux and membrane potential, various scientists are working to design novel batteries. Scientists recently found a molecule with the formula Li2 C6 O6 that really can transiently Lithium ions having an energy density such that are introduced and removed almost double those of current lithium methyl carbonate (LiNi1/3n1/3Co1/3O2) electrodes. This compound could be produced from a renewable resource, myoinositol [57]. Electrodes are a vital part of a battery. Essentially, batteries using lithium sulphur electrodes may store four times as much electricity as those with standard lithium-ion electrodes. This would allow both extended playback durations for devices as well as a higher range of electric vehicles between charges. Some researchers assert that even these batteries are close to being commercially viable. A new layout uses components like graphene oxide with a sulphur coating has the potential to increase battery life while retaining high storage capacity [58]. The efficient class of ecofriendly green catalysts designed by Terry Collins of Carnegie Mellon University and based on naturally occurring peroxidase enzymes (TAML) has the potency to diminish the environmental risk of such a pharmaceutical sector [51]. Collins believes that utilizing such catalysts later inside the sewage-disposal plant could enable to decompose into a wide array of chemical remnants, such as problems caused either by birthcontrol pills, Prozac, Lipitor and other medications once it goes into the environment [53,54,59].

5.11 Challenges in research It is impossible to go into great depth about most of the barriers that must be resolved for research to advance new techniques and approaches. Furthermore, a review of most of the concerns gives an example of existing problems and could inspire thought about further problems that should have been included: 1. Changes made with energies instead of with material. 2. Creation of such a “toolbox” of synthetic techniques that would be both environmentally friendly and economically advantageous. 3. Polymeric materials and composites made without additives and optimized for safe decomposition. 4. Designing products with inbuilt entropy in mind to facilitate reuse and recycling considerations. 5. The emergence of “preventative toxicology” involves consistently designing industrial chemicals with more and more knowledge about multiple environmental modes of action.

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6. Production of some more effective, lower energy-intensive solar cells. 7. Introduction of power sources that do not burn fuel and do not use a lot of materials 8. Research initiatives to support the transfer of knowledge and technology between administration, industry or even research organizations.

5.12 Conclusion Green chemistry attempts to ensure the sustainability of chemistry while also lowering the generation of waste and/or developing new items using minimal environmental resource utilization. If molecular research would be to overcome the concerns of sustainable development, it must enhance the progress of green chemistry during the previous 10 years. The revolt of one day would become the new innovative orthodoxy of the next, as per a popular saying. The emphasis, revealing and designation of “green chemistry” would not be necessary until the 12 fundamentals principles of green chemistry were merely implemented as a fundamental component of regular chemistry. The field of green chemistry will be around to remain, and also in the upcoming years, its influence is expected to grow much more. The significant proportion of chemical compounds used in the industry might also be benign by design within your lifetime, depending on how promptly it has gained credibility as a science discipline and how frequently green chemistry has an impact. The positive improvements that industrial green chemistry is driving and instead will promote appraisal for our planet may also be greatly influenced by everyone.

References [1] R. Ratti, Industrial applications of green chemistry: status, challenges, and prospects, SN Appl. Sci. 2 (2020) 263. Available from: https://doi.org/10.1007/s42452-020-2019-6. [2] U. Chanshetti, Green chemistry: challenges and opportunities in sustainable development, Int. J. Curr. Res. 6 (2014) 9558 9561. [3] B. Sezen, S.Y. C ¸ ankaya, Effects of Green manufacturing and eco-innovation on sustainability performance, Proc. Soc. Behav. Sci. 99 (2013) 154 163. Available from: https://doi.org/10.1016/j.sbspro.2013.10.481. [4] S.K. Sharma, A. Mudhoo, W. Zhang, Chemistry and engineering, Green Chemistry for Environmental Sustainability, CRC Press, 2011. Available from: https://doi.org/10.1201/EBK1439824733. [5] A. Singh, S. Singh, N. Singh, Green chemistry; sustainability an innovative approach (green chemistry and sustainability), J. Appl. Chem. 2 (2014) 77 82. [6] J.H. Clark, Green chemistry: challenges and opportunities, Green Chemistry (1999). February. [7] S.K. Ritter, EPA analysis suggests green success, Chem. Eng. News. 93 (2015) 32 33. [8] P. Anastas, Twenty years of green chemistry, Chem. Eng. N. 89 (26) (2011) 62 65. [9] American Chemical Society. History of Green Chemistry. 2015, ,http://www.acs.org/content/acs/en/ greenchemistry/what-is-green-chemistry/history-of-green-chemistry.html. (accessed 26.05.15). [10] P.T. Anastas, J.C. Warner, Green Chemistry, Theory, and Practice, Oxford University Press, Oxford, 1998. [11] S. Chandrasekaran, B.C. Ranu, G.D. Yadav, S. Bhanumati, Monographs on Green Chemistry Experiments, GC Task Force, DST, 2009. [12] O.V. Kharissova, B.I. Kharisov, C.M. Oliva Gonza´lez, Y.P. Me´ndez, I. Lo´pez, Greener synthesis of chemical compounds and materials, R. Soc. Open. Sci. 6 (2019) 191378. Available from: https://doi.org/10.1098/rsos.191378. [13] M.M. Unterlass, Green synthesis of inorganic-organic hybrid materials: state of the art and future perspectives, Eur. J. Inorg. Chem. (2016) 1135 1156. Available from: https://doi.org/10.1002/ejic.201501130.

Green Chemistry Approaches to Environmental Sustainability

106

5. Approaches and challenges with respect to green chemistry in industries

[14] S. Bhandari, V. Kasana, Applications of green chemistry principles in agriculture, Green. Chem. Tech. Lett. 4 (2018) 10 12. Available from: https://doi.org/10.18510/gctl.2018.422. [15] G. Singh, S. Wakode, Green chemistry drift: a review, Sch. Acad. J. Pharm. 7 (2018) 274 279. Available from: https://doi.org/10.21276/sajp.2018.7.6.10. [16] A. Ivankovic, S. Talic, Review of 12 principles of green chemistry in practice, Int. J. Suit. Greenener 6 (2017) 39 48. Available from: https://doi.org/10.11648/j.ijrse.20170603.12. [17] R. Escobedo, R. Miranda, J. Martı´nez, Infrared irradiation: toward green chemistry, a review, Int. J. Mol. Sci. 17 (2016) 453. Available from: https://doi.org/10.3390/ijms17040453. [18] S. Manmohan, S. Arjun, S.P. Khan, S. Eram, N.K. Sachan, Green chemistry potential for past, present and future perspectives, Int. J. Res. Pharm. 3 (2012) 31 36. [19] A. Valavanidis, T. Vlachogianni, K. Fiotakis, Laboratory experiments of organic synthesis and decomposition of hazardous environmental chemicals following green chemistry principles, in: Proceedings of the International Conference Green Chemistry and Sustainable Development, Thessaloniki, 9 (2009) 25 26. Paper for Conference Proceedings. [20] S.K. Ritter, Seeing the Green Side of Innovation, Chem. Eng. News. 92 (26) (2014) 24 28. [21] S. Cichosz, A. Masek, Superiority of cellulose non-solvent chemical modification over solvent-involving treatment: solution for green chemistry (Part-I), Materials 13 (2020) 2552. Available from: https://doi.org/ 10.3390/ma13112552. PMid:32503319 PMCid:PMC7321458. [22] G.A. Lasker, K.E. Mellor, N.J. Simcox, Green chemistry & chemical stewardship certificate program: a novel, interdisciplinary approach to green chemistry and environmental health education, Green. Chem. Lett. Rev. 12 (2019) 178 186. Available from: https://doi.org/10.1080/17518253.2019.160960. [23] F. Fanelli, G. Parisi, L. Degennaro, R. Luisi, Contribution of microreactor technology and flow chemistry to the development of green and sustainable synthesis, Beilstein J. Org. Chem. 13 (2017) 520 542. Available from: https://doi.org/10.3762/bjoc.13.51. [24] J.L. Tucker, Green chemistry, a pharmaceutical perspective, Org. Process. Res. Develop. 10 (2006) 315 319. Available from: https://doi.org/10.1021/op050227k. [25] BASF SE Methods for the Separation of Acids From Chemical Reaction Mixtures Employing Ionic Fluids (2003). World Patent WO/2003/062251. [26] P.J. Dunn, S. Galvin, K. Hettenbach, The development of an environmentally benign synthesis of sildenafil citrate (Viagrat) and its assessment by Green Chemistry metrics, Green. Chem. 6 (2004) 43 48. Available from: https://doi.org/10.1039/B312329D. [27] U.S. Environmental Protection Agency. Presidential Green Chemistry Challenge Awards: 2012 Greener Synthetic Pathways Award. 2015. ,http://www2.epa.gov/green-chemistry/2012-greener-synthetic-pathways-award. (Accessed 30.06.15). [28] American Chemical Society. Examples of green chemistry. 2015. ,http://www.acs.org/content/acs/en/ greenchemistry/what-is-green-chemistry/examples.html. (Accessed 30.06.15). [29] U.S. Environmental Protection Agency. Presidential green chemistry challenge awards: 2010 greener reaction conditions award, 2015. , http://www2.epa.gov/green-chemistry/2010-greener-reaction-conditions-award . (Accessed 30.06.15). [30] U.S. Environmental Protection Agency. Presidential green chemistry challenge awards: 2004 greener synthetic pathways award, 2015. ,http://www.epa.gov/greenchemistry/pubs/pgcc/winners/gspa04.html. (Accessed 30.06.15). [31] American Chemical Society. 12 Principles of Green Chemistry. Available from: http://www.acs.org/content/acs/en/greenchemistry/what-is-green-chemistry/principles/12-principles-ofgreen-chemistry.html. [32] M. McCoy, Cleaning product makers bask in new solvents, Chem. Eng. N. 93 (3) (2015) 16 19. [33] P. Azadi, R. Carrasquillo-Flores, Y.J. Paga´n-Torres, E.I. Gu¨rbu¨z, et al., Catalytic conversion of biomass using solvents derived from lignin, Green Chem. 14 (2012) 1573 1576. [34] S.K. Ritter, Depolymerized lignin makes a good solvent, Chem. Eng. N. 90 (24) (2012) 36. [35] C.M. Cooney, Liquor-store spirits provide green alternative to HPLC solvents, Chem. Eng. News. (2015). Available from: http://cen.acs.org/articles/93/web/2015/04/Liquor-Store-Spirits-Provide-Green.html. [36] C.J. Welch, T. Nowak, L.A. Joyce, E.L. Regalado, Cocktail chromatography: enabling the migration of HPLC to nonlaboratory environments, ACS Sustain. Chem. Eng. 3 (2015) 1000 1009. Available from: https://doi. org/10.1021/acssuschemeng.5b00133.

Green Chemistry Approaches to Environmental Sustainability

References

107

[37] U.S. Environmental Protection Agency. Presidential Green Chemistry Challenge Awards: 2003, Greener Reaction Conditions Award. http://www2.epa.gov/green-chemistry/2003-greener-reaction-conditions-award. [38] E.I. du Pont de Nemours and Company. DuPont Bio-Based Polymer Platform Earns Green Chemistry Award. (2015). Available from: http://www.dupont.com/corporate-functions/our-approach/science/scientists-engineers/awards-and-recognition/articles/green-chemistry-award.html. [39] K. Laird, BASF successfully produces first commercial volumes of renewably-sourced 1,4 butanediol. Plastics Today November 27, 2013. ,http://www.plasticstoday.com/articles/basf-successfully-produces-first-commercial-volumes-renewably-sourced-14-butanediol. (Accessed 02.07.15). [40] M. Jacoby, Teaming up for bio based chemicals, Chem. Eng. N. 90 (2012) 37 38. [41] A. Scott, Making palm oil sustainable, Chem. Eng. N. 93 (9) (2015) 19 21. [42] A.H. Tullo, Hunting for biobased acrylic acid, Chem. Eng. N. 91 (46) (2013) 18 19. [43] M.M. Bomgardner, Interest in biobasedlevulinic acid grows, Chem. Eng. N. (2015). Available from: http:// cen.acs.org/articles/93/web/2015/03/Interest-BiobasedLevulinic-Acid-Grows.html. [44] J. Jean, R.B. Brown, R.L. Jaffe, T. Buonassisi, V. Bulovi´c, Perspective: pathways for solar photovoltaics, Energy Environ. Sci. 8 (2015) 1200 1219. Available from: https://doi.org/10.1039/C4EE04073B. [45] M. Jacoby, Tapping solar power with perovskites, Chem. Eng. N. 92 (2014) 10 16. [46] Y. Zhou, M. Yang, W. Wu, A.L. Vasiliev, et al., Room-temperature crystallization of hybridperovskite thin films via solvent solvent extraction for high-performance solar cells, J. Mater. Chem. A 3 (2015) 8178 8184. Available from: https://doi.org/10.1039/C5TA00477B. [47] P. Patel, New Trick Promises Perovskite Solar Films for Windows and Walls. IEEE Spectrum Jan 7, 2015. ,http://spectrum.ieee.org/energywise/green-tech/solar/new-trick-promisesperovskite-solar-films-for-windows-and-walls. (Accessed 05.07.15). [48] K. Greene, Understanding Quantum Dots from The Inside Out. IEEE Spectrum October 21, 2013 ,http:// cen.acs.org/articles/91/web/2013/10/Understanding-Quantum-Dots-Inside.html. (Accessed 05.07.15). [49] D. Johnson, Quantum Dots with Built-in Charge Could Lead to Highly Efficient Solar Cells. IEEE Spectrum 23 Jan 2012. ,http://spectrum.ieee.org/nanoclast/semiconductors/nanotechnology/quantum-dots-withbuilt-in-charge-could-lead-to-highly-efficient-solarcells. (Accessed 05.07.15). [50] Z. Pan, I. Mora-Sero, Q. Shen, H. Zhang, et al., High-efficiency “green” quantum dot solar cells, J. Am. Chem. Soc. 136 (25) (2014) 9203 9210. Available from: https://doi.org/10.1021/ja504310w. http://pubs.acs. org/doi/abs/10.1021/ja504310w. [51] W.C. Ellis, C.T. Tran, M.A. Denardo, A. Fischer, A.D. Ryabov, T.J. Collins, Communication: design of more powerful iron-TAML peroxidase enzyme mimics, J. Am. Chem. Soc. 131 (50) (2009) 18052 18053. Available from: https://doi.org/10.1021/ja9086837. [52] U.S. Environmental Protection Agency. Presidential Green Chemistry Challenge Awards: (1999) Academic Award. http://www2.epa.gov/green-chemistry/1999-academic-award. [53] S. Everts, Better living through green chemistry: pharmaceuticals, N. Scientist 15 (2010) 57. [54] N.W. Shappell, Estrogenic activity in the environment: municipal wastewater effluent, river, ponds, and wetlands, J. Environ. Qual. 35 (2006) 122 132. Available from: https://doi.org/10.1021/es7022863hazardsorganic solvents. Available from: www2.epa.gov/green-chemistry/2006. [55] M.M. Bomgardner, Making fuel cell vehicles an [almost] affordable reality, Chem. Eng. N. 92 (2014) 17 20. [56] D. Larcher, J.M. Tarascon, Towards greener and more sustainable batteries for electrical energy storage, Nat. Chem. 7 (2015) 19 29. [57] H. Chen, M. Armand, G. Demailly, F. Dolhem, P. Poizot, J.M. Tarascon, From biomass to a renewable LixC6O6 organic electrode for sustainable Li-ion batteries, ChemSusChem. 1 (4) (2008) 348 355. [58] M.K. Song, Y. Zhang, E.J. Cairns, A long-life, high-rate lithium/sulfur cell: a multifaceted approach to enhancing cell performance, Nano Lett. 13 (2013) 5891 5899. Available from: https://doi.org/10.1021/nl402793z. [59] U.S. Environmental Protection Agency. Presidential Green Chemistry Challenge Awards: 1999 Academic Award, 2015. ,http://www2.epa.gov/green-chemistry/1999-academic-award. (Accessed 05.07.15).

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C H A P T E R

6 Full blown green metrics Payal B. Joshi1,2, Nivedita Chaubal-Durve1 and Chandra Mohan3 1

Department of Basic Sciences, Mukesh Patel School of Technology Management and Engineering SVKMs NMIMS, Mumbai, Maharashtra, India 2Operations and Method Development, Shefali Research Laboratories, Mumbai, Maharashtra, India 3Department of Chemistry, School of Basic and Applied Sciences, K. R. Mangalam University, Gurugram, Haryana, India

6.1 Introduction You can’t manage what you don’t measure.—Peter F. Drucker

The above quote is poignant to support our understanding on green chemistry and its metrics. The genesis of the concept of green chemistry is threefold namely, 1. Eliminating hazardous reagents and solvents in chemical synthesis. 2. Minimal to zero waste generation during chemical processes. 3. Performing chemical reactions in an efficient manner in terms of energy, raw materials, and minimum steps to obtain the product. To achieve the above, a vigorous endeavour in synthetic chemistry is to design chemical reactions and processes that are “benign-by-design”. Since the inception of the fundamental 12 principles of green chemistry was proposed, the concept gained momentum to apply them judiciously in various chemical synthetic processes and industrial activities [1]. In early 1980s, waste generation and use of toxic materials in industrial processes were the two major challenging situations. Waste is not a product of nature, rather it is manmade and thus necessitated our obligation to solve this problem. During that time, phloroglucinol, a pharmaceutical intermediate, was manufactured with a 90% yield using 2,4,6
trinitrotoluene (explosive) and potassium dichromate-oleum mixture (oxidant). The glaring issues of explosive raw material, numerous by-products, waste generation, and carcinogenic chromium in oxidizing reagent led to a green metric called E factor. E factor

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is a green metric that takes into account the mass ratio of waste generated to the desired product of a chemical reaction [2]. At that time, the use of standard calculations on product yield and atom economy was known, but seemed insufficient. This led to surmounting work that led to measuring greenness of chemical processes and reaction using a standard measure called green metrics. Green metrics is defined as, “quantitative measure or a framework designed for chemical reactions that denote environment impact, yield, and economic viability on scale-up”. Today, efforts are taken to approach the problem by selecting renewable feedstocks as starting raw materials. Yet, it is a myopic solution, as there are many reactions that turn energy-inefficient if started with renewable materials. For example, hexamethylene diamine (HDMA) is one of the important starting materials to prepare nylon-6,6, an essential industrial polymer. Scheme 6.1 depicts the preparation of HMDA using starch and 1,3butadiene as a starting material. Dros et al. [3] reported bio-based route to synthesise HMDA that led to eutrophication as the process involved drying of hydromethylfurfural. Also, to obtain starch, one needs to grow potato and corn that requires land. It was realized that growing energy crops along with agricultural crops may cause competition for land use and thus is a nongreen and an unsustainable approach. It is axiomatic that one cannot have all problem-one solution strategy for greening the chemical processes. We must realize that most green chemistry principles that were imbibed by Environmental Protection Agency (EPA) in 1990s focused on waste prevention rather than core redesigning of chemical reactions for industrial scale-up. When moving from laboratory scale to pilot plant, green chemistry takes a different turn navigating our need to reinvent our analytical methods. Chemists and chemical engineers are making concerted effort in this direction to achieve green quotient of chemical reactions. This pressing need of redesigning existing

Starch (renewable feedstock)

enzymatic

conversion

CH2OH

OH

O

H

O

dehydration and hydrogenation

OH

HO

Hexamethylfurfural (HMF) O OH

CH2OH

OH H Fructose

oxidation, reductive amination and dehydrooxygenation NH2 H2N

Hexamethylenediamine (HMDA)

N

CH2 H2C

hydrocyanation

Ni-tri-o-tolyl phosphite catalyst

1,3-butadiene

N

adiponitrile

hydrogenation

SCHEME 6.1 Preparation of hexamethylene diamine.

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chemical reactions, environmental concerns and industrial requirements brought green analytical chemistry (GAC) into forefront. On literature review, it is evident that prior to popularization of green chemistry, engineers were consciously developing analytical methods to reduce solvents, miniaturize instruments and recycle waste. At present, GAC is pivoting towards low-cost miniature instruments, rapid real-time analysis, easy data acquisition and open data as measures towards greenness. With complex chemistries, it is impractical to look at standalone chemical reaction—as they will always seem nongreen. We need to devise green metrics and life cycle analysis that reflects overall greener quotient of entire chemical process.

6.1.1 Motivation and goal of the chapter Inspired by examples presented in the above section, this chapter discusses green metrics utilized in synthetic and analytical chemistry. Atom economy and selected energy metrics are discussed with industrially relevant examples and our review on organic synthesis greenness quotient. Next, we discuss greener analytical methods using miniature instruments and bio-based solvents. Further, we have provided an overview of sustainability metrics and their equations that shall provide an expanse to our readers on the topic. Excellent review articles are found in literature on green metrics, but there is scant coverage on comprehensive overview connecting greener approaches for synthesis, analytical processes and sustainability metrics. It is opined that these concepts are intertwined and requires a unified understanding to achieve green chemistry principles.

6.2 Greening of industrial synthesis: a compelling necessity Synthetic organic chemistry is a mature field and chemists are striving for improvising strategies for commercializing target molecules. The landscape of the industries has shifted from only-profit mode to the people, planet and profit for attaining sustainability [4]. Tucker and Faul [5] discussed a case study on drug company, Amgen, that inculcated sustainable practices in drug discovery programme by blending green chemistry principles and triple bottom line approach so as to sustain business model of industries. The major hurdle in greening organic synthesis is the resistance to change age-old protocols. Witnessing the warnings of environmental degradation, design rules must be followed by evaluating chemical processes thereby making them sustainable along with lifecycle assessment. In the next section, we have chosen only those reactions that are currently practiced and have significance in industrial applications. The green metrics calculations are applied to the chosen chemical processes and discussed.

6.2.1 Are waste metrics reliable? In synthetic chemistry, atom economy and E factor are the easy-to-apply metrics to evaluate greenness quotient of chemical reactions. These green metrics provide first-hand information without any experiments and thus easy to apply on chemical reactions whose

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greenness needs to be determined. Table 6.1 provides the different green metrics and their equations that are routinely employed to calculate greenness of chemical reactions. The use of natural feedstock/renewable resource is always preferred over synthetic raw materials to achieve green quotient. For simplicity and as a good starting point, we provide calculations of E factor, AE, and EMY. Following our discussion on HDMA synthesis, let us take another example of alcohol production from sucrose, an agricultural feedstock: It is evident from Scheme 6.2 that sucrose, hexose, ethanol, water and carbon dioxide are nontoxic in nature. So, taking into consideration their nontoxic nature and use of renewable resource, sucrose biocatalysis comes across as an ecofriendly process. However, the green metrics do portray an opposite picture even though the protocol is greener. Hence, theoretical stoichiometry cannot be always reliable. Scheme 6.3 illustrates industrial production of aniline, an important industrial bulk chemical manufactured by two chemical routes viz, Be´champ reduction and DuPont reduction. Thus it is pointed out that single-step metrics do not reflect green chemical reaction in true sense. We must reiterate that growing crops for obtaining sucrose must consider challenges of sustainable agriculture as discussed earlier in Section 6.1. Michel [11] had also argued on issues such as photosynthetic inefficiency and inefficient land usage as major challenges to foresee biofuels. Next, we move ahead to the calculations shown in Schemes 6.3 and 6.4. It is evident that DuPont reduction is greener than classic Be´champ reduction and follows green chemistry principle #9 related to catalysts versus stoichiometric reagents. Coming to answering the question in this subsection is no straightforward endeavour. This led to developing life cycle assessment to reveal the greener quotient of TABLE 6.1 Selected green metrics equations used in organic synthesis. Green metrics Atom economy (AE)

Equations MW P of desired product MW of reactants

Reference 3 100 where, MW refers to molecular weight

Trost [6]

E factor

total mass of waste; kg total mass of final product; kg

Sheldon [7]

Mass intensity (MI)

total mass in process step; kg mass of final product; kg

Constable, Curzons, and Cunningham [8]

Mass productivity (MP)

mass of product; kg total mass in process step; kg

Reaction mass efficiency (RME)

mass of final product; kg total mass of reactants; kg

Process mass intensity (PMI)

total mass in process stepðwith waterÞ; kg mass of the product; kg

Carbon efficiency (CE) Effective mass yield (EMY)

3 100

3 100

amount of carbon in product P 3 100 carbon present in reactants

amount of carbon 5

P P carbon in product 3 100 carbon in reactants

moles of product 3 moles of product 3

mass in process step; kg mass of nontoxic reactants; kg

3 100

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6.2 Greening of industrial synthesis: a compelling necessity

MW

SCHEME 6.2

C12H22O11 + H2O (342) (18)

2C6H12O6 (360)

2C2H5OH+2CO 2 (92) (88)

Biocatalysis of sucrose. E Factor :

88 92 92 5 0:957 AE : 3 100 5 25:55% EMY : 3 100 5 26:90% 92 360 342

NO2

NH2 + 2H2 O + 2FeCl3

+ 2Fe + 6HCl

aniline

nitrobenzene MW

SCHEME 6.3

(123)

(112)

(93)

(36)

(324)

Production of aniline via Be´champ reduction [10]. E Factor:

SCHEME 6.4

(219)

360 93 93 5 3:87 AE: 3 100 5 20:48% EMY: 3 100 5 75:61% 93 454 123

Production of aniline via DuPont reduction (US Patent No. US4415754A, 1983 [12]).

36 0 93 93 5 0:387 ðwith H2 OÞ; 5 0:0 ðwithout H2 OÞ AE : 3 100 5 72:09% EMY : 3 100 5 75:61% E Factor : 93 93 129 123

complete chemical process. These metrics though reveal only greenness of a single step, it is a good starting point and provides an overview to the chemists. We have discussed sustainability metrics in later part of the chapter.

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6.2.2 Current industrial processes and metrics Apart from the examples discussed in earlier section, there are other important chemical processes carried out in industries due to their good yields and wider applications. The selected chemical reactions are methanol carbonylation, benzaldehyde production, fluorination and photocatalysis. We selected these reactions due to use of non-toxic raw materials and their industrial relevance. Diels-Alder reaction and rearrangement reactions have proven atom-efficiency, thus not included in the review. Table 6.2 elucidates green metric calculations in stoichiometric amounts that may differ if considered in an industrial scale-up. In all four selected examples, it is observed that catalytic conversion is a predominant feature. Methanol carbonylation is an industrial-scale process to manufacture acetic acid commercially using iridium/iodide-based catalyst. The process of carbonylation was TABLE 6.2 Features of selected chemical reactions of industrial importance. Chemical reactions

Features

Cavita process for methanol carbonylation [13] Ir/HI CH3OH + CO CH3COOH(E factor 5 0; AE 5 100% and

Involves iridium catalyst, no waste generation

*(32)

(28)

(60)

EMY 5 100%)

Production of benzaldehyde [14] OH

Use of green Na-MnOx catalyst with long shelf-life, water as a by-product that can be recycled

O Na-MnOx,O 2

+ 0.5O2

hydrobenzoin (214)

H

2

EtOH,70°C,30min

OH

benzaldehyde (212)

(16)

+ H2O

(E

(18)

factor 5 0.08; AE 5 92.17% and EMY 5 92.17%) Fluorine is small and an atom-efficient electrophilic reagent, use of Si/C flow reactor eases handling of fluorine and nitrogen

Synthesis of flucytosine [15] O O N

NH

10% F2 in N2 (0.7mol/h), HCOOH (1M) Si/C flow reactor

H2N

N

NH

(E factor 5 0;

H2N F flucytosine (129)

cytosine (111)

AE 5 66.15% and EMY 5 86.57%) Imine formation via photocatalysis [16] NH2

TiO2, visible light

N

Photocatalysis is a greener approach, milder reaction conditions(*figures in parenthesis indicate molecular weights)

O2 (1atm), CH3CN

benzylamine (107)

2-Diphenylethan-1-imine (195)

(E factor 5 0; AE 5 91.12% and EMY 5 91.12% (assuming 2 moles of benzylamine))

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improvised by replacing rhodium-catalyst by iridium/iodide catalyst that led to reducing water usage in the process. At present, synthetic chemists are struggling to replace toxic and expensive palladium catalysts in organic synthesis. Iron, nickel, manganese, copper, cobalt and iridium-based catalyst are some examples of metal-based catalysts replacing palladium catalyst in the coming years. Benzaldehyde production via oxidative cleavage of hydrobenzoin is a typical green process that can be easily scaled-up in industrial plants. As shown in Table 6.2, hydrobenzoin is oxidized in the presence of Na-MnOx catalyst under mild conditions. Escande et al. [14] reported the preparation of heterogeneous Na-MnOx catalyst and its superior catalytic activity in oxidative cleavage of vicinal diols. The catalytic activity of Na-MnOx was compared with lead tetraacetate and sodium periodate catalysts for their greenness quotient and sustainability. It was revealed that Na-MnOx catalyst could be reused multiple times in the reaction with an E factor of 0.8 which was much better than lead tetracetate and sodium periodate catalysts. Additionally, Na-MnOx catalyst utilized ethanol as a solvent which was comparatively greener than dichloromethane and benzene which are used with lead tetracetate and sodium periodate catalysts. Next example is the synthesis of flucytosine, an antifungal drug. Fluorination is another challenging organic reaction required to prepare antifungal drugs. The major concern is safe handling of fluorine reagent in laboratory conditions and eventually its potential scale-up in industries. Another intriguing organic reaction that is extensively studied is amine oxidation using photocatalysts. TiO2-based photocatalytic oxidation is a green process that is finding its way in industrial setting. Lang et al. [16] reported the conversion of benzylamine to its imine derivative using TiO2 photocatalyst activated by visible light. Though the reaction is green, its only drawback is the use of acetonitrile solvent. TiO2 photocatalysts are well documented in published literature as green catalysts, yet its industrial scale-up is rarely discussed. Some of the major challenges of industrial scale-up of photocatalysis are use of artificial light irradiation, designing flow reactors and downstream processes. Lee et al. [17] described photocatalytic cycloaddition reaction in a flow reactor that obtained products of about 7.45 kg per day. Recently, Wan et al. [18] demonstrated flow reactors with advanced light emitting diodes to carry out direct amination of aliphatic compounds. They achieved an industrial scale-up with products of over 2 kg per day. Harper et al. [19] demonstrated trifluoromethylation of 2-chlorothiophenol using ruthenium-based catalyst and trifluoroiodomethane that yielded over 500 kg product. All these efforts express the significant interest of researchers to outgrow photocatalysis from being laboratory-scale green catalysis to a commercial process.

6.3 Overview on green analytical chemistry Analytical methods involve trace quantities of solvents and chemicals compared to organic synthesis. Thus one needs to investigate the analytical processes to disprove this myopic viewpoint. A routine high performance liquid chromatography (HPLC) analysis (with 25 cm column length, 4.6 mm internal diameter and 1.5 mL/min flowrate) generates over 1 L of effluent daily. This may become an environmental concern if one operates over 100 HPLC instruments in an industrial setting. A rigorous endeavour of an analytical

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chemist is to design analytical procedures keeping environment, health, and safety concerns to achieve the goals of GAC [20]. Malissa [21] introduced the concept of “ecological paradigm” that related analytical chemistry to environmental protection and ecosystem preservation. However, the “greener” analytical methods are not easy to quantify as organic synthesis as there is no product as an outcome with a known mass. Thus one needs to design analytical protocols such that it involves lesser solvents, be energy efficient and cause minimal waste generation. Since 1970s, novel analytical techniques were designed to meet two requirements as follows: 1. greener analytical methods that must improve analytical figures of merit. 2. to reduce waste generation and improve operator safety and energy efficiency. Earliest effort on pivoting greener approaches in analytical chemistry was brought to light when Guardia et al. [22] described miniaturization that allowed replacing toxic reagents. The experimental evidence was initiated when a carbamate pesticide, propoxur, was determined in water and the major outcome of the experiment was reduced waste. GAC gained popularity in the early 1970s due to flow methodologies. Flow methodology is an analytical technique that relies on introduction, processing and detection of samples in a flowing media [23]. It encompasses analytical techniques such as flow injection analysis, lab-on-a-chip, lab-in-a-syringe and lab-on-a-valve [24]. These analytical techniques led to the adoption of automation and miniaturization of sample analysis that had prowess of higher sample throughput. Further, flow analysis methods reduced sample consumption, reagent use, operator intervention and waste generation, thus making it a greener alternate to existing analytical methods. Today, miniaturized or portable versions of most analytical instruments have been reported under two categories, namely, miniature extraction and miniature separation techniques. Much of the emphasis of greening analytical methods relied on solvent or mobile phase changes for extraction and separation techniques, respectively. However, these measures provide only an incremental change towards GAC principles, not in entirety. Fig. 6.1 depicts the present and future scenario of GAC and suggests the use of cloud-based analytical software for open data.

FIGURE 6.1 Current and future scenario of green analytical techniques.

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Also, it represents Findable, Accessible, Interoperable, Reusable (FAIR) guidelines and metrics calculations as retained features while greening analytical techniques. It is opined that there are many bench-top based sophisticated analytical methods that need redesigning to be considered a greener technique. Earlier, it seemed overwhelming, but at present with rapid advancement in computing power, compatible detectors and diverse column sizes it has opened avenues towards portability and miniaturization.

6.3.1 Developed green analytical metrics One of the earliest known metrics that assessed greenness of an analytical procedure called NEMI was developed in 2002 by Methods and Data Comparability Board (MDCB). NEMI is a database that provides details on environmental protocols, statistical and analytical procedures [25]. It also allows chemists to compare the methods to understand all the phases of environmental monitoring. With 1209 searchable analytical methods and 19 protocols, it represents the result in a circular pictogram depicting four quadrants, each of them characterized by different criteria as listed below: 1. PBT implies presence of persistent, bioaccumulative, and toxic EPA’s TRI (Toxics Release Inventory) list of chemicals. 2. Hazardous meant that to fulfil this criterion chemicals should not fall in the category of Resource Conservation and Recovery Acts. 3. Corrosive implies that the sample pH must be of 2
12 in entire analytical operation. 4. Waste generated in the analytical process must be less than 50 g. Above points are considered such that if a criterion is met, the respective quadrant of the circular pictogram turns green or else remains colourless. NEMI is a semiquantitative tool and involves a time-consuming search that necessitates filling every quadrant of the pictogram. NEMI Greenness Profile is an improvised version that includes energy consumption metric and assigns scores 1
3 to each feature. According to Guardia and Armenta [26] NEMI pictogram was improvised by incorporating four additional quadrants, namely, chemist risk, energy, reagents consumed and volume of waste. They suggested colour codes of green, orange and red to quantify low, medium and high risks respectively possible in an analytical procedure. Even with these improvisations, NEMI suffers as a good metric due to time-consuming chemical search. Gałuszka et al. [27] proposed Analytical Eco-scale (AES) metric that assigned penalty points to each criterion that is a nongreen feature of the analytical procedure. The penalty points for waste generation, high energy input, toxic chemicals and reagents are subtracted from the base value of 100, 100 being an ideal green analytical procedure expressed as Eq. (6.1) AES 5 100 2 total penalty points

(6.1)

If the eco-scale score is closer to 100, the analytical procedure is considered as green and those scored below 50 are considered as an inadequate green method. Eco-scale was improvised further by Armenta, Guardia, and Namiesnik [28] by proposing green certificate. Using mathematical equation and classified colour codes (A to G, with A being the

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6. Full blown green metrics

greenest), penalty points are calculated. Penalty points are assigned to non-green features of the analytical processes. On plotting the penalty points against amount of waste generated or volume of consumed reagents, following mathematical relationship is established: PPR 5 ð0:16 6 0:05ÞVð0:31 6 0:02Þ

(6.2)

PPW 5 ð0:50 6 0:08ÞWð0:4 6 0:02Þ

(6.3)

and

In Eqs. (6.2) and (6.3), PPR refers to penalty points for reagents and PPW refers to generated waste. On solving the above equations, Eq. (6.4) is obtained as: Green certificate 5 100 2 total penalty points

(6.4)

Płotka-Wasylka [29] proposed a semiquantitative metric called the Green Analytical Procedure Index (GAPI). It evaluated greenness of entire analytical procedure right from sample preparation to quantification of the analyte. GAPI utilized all the features of ecoscale colour codes and pictograms of earlier metrics and designed a metric with five pentagrams. These five pentagrams incorporated 15 parameters that allowed assigning one of the three colour codes, namely, red, yellow and green that represented high, medium and low environmental impact (EI). Pena-Pereira et al. [30] proposed a comprehensive assessment tool called Analytical Greenness Metric Approach and Software (AGREE) to calculate greenness of analytical process. They obtained assessment criteria from the 12 GAC principles and converted in 0
1 metric scale. AGREE metric pictogram indicated the final score, analytical method performance in all criteria and weights assigned by the chemist. They demonstrated AGREE metrics by applying on three different procedures for determining polybrominated diphenyl ethers in soil samples. Hartman et al. [31] provided Eq. (6.5) for analytical method volume intensity (AMVI) to determine solvent consumed and effluent generated in HPLC technique. This metric utilized EI and efficiency to measure greenness of an analytical technique and calculated as follows: total solvent consumption (6.5) number of analyte peaks in a chromatogram  P solvent consumption 5 HPLC solvents1sample preparation solvents 3 replicates AMVI 5

where Eq. (6.6) Eq. (6.5) also considers the number of analyte peaks to account for the efficiency of the chromatographic separation. For example, an HPLC method consumed 1620 mL solvent and resulted in a chromatogram with 12 resolved analyte peaks, and its AMVI will be 135 mL/component. If we reduce the solvent consumption to 360 mL with same number of analyte peaks on a chromatogram, its AMVI will be 30 mL/component. Thus AMVI metric suggests that the latter analytical method is a greener alternative for HPLC analysis. As against earlier metrics, Gaber et al. [32] developed HPLC-EAT (Environmental Assessment Tool) to assess liquid chromatographic systems only. HPLC-EAT takes into

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account health, safety and EI of all the solvents employed in the HPLC method and is expressed as follows: HPLC 2 EAT 5 S1 m1 1 H1 m1 1 E1 m1 1 S2 m2 1 H2 m2 . . . 1 Sn mn 1 Hn mn 1 En mn

(6.6)

where E, H and S are environment, health and safety parameters respectively calculated as per Koller, Fischer, and Hungerbu¨hler [33] for different solvents where m and n denote mass and total number of the solvents, respectively. The final score obtained from Eq. (6.6) was validated using GlaxoSmithKline solvent selection tool. The only limitation with this method is its sole criterion on solvents as an EI of HPLC technique. However, it is not entirely incorrect to place emphasis on solvents due to the nature of HPLC analysis using large volumes of solvent. Yet, while discussing green metrics, we need to decide on multiple criteria to consider a method as greener alternative in a real sense. This brings us to move towards statistical metrics. Multicriterial decision analysis (MCDA) allows ranking of analytical methods based on their greenness quotient. Fig. 6.2 depicts various steps of decision analysis applied in analytical chemistry. MCDA follows various steps such as, defining goal of analysis, choosing quantitative parameters to elucidate the goal and identifying routes to achieve the goal. After these steps are completed, one of the MCDA algorithms is applied and ranking of different analytical methods are obtained. Some of the commonly employed MCDA tools are AHP (Analytical Hierarchical Process) [34], PROMETHEE (Preference Ranking Organization Method for Enrichment Evaluations) [35], TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) [36], MAVT (Multi Attribute Value Theory) [37], ELECTRE (ELimination and Choice Expressing Reality) [38], Simple Additive Weighting [39] and, MAUT (Multi Attribute Utility Theory) [40]. It is observed that when green metrics are applied to standard analytical protocol methods, they are found to be nongreen in a true sense. This becomes a problem as standard analytical protocols are routinely employed in analytical laboratories. MCDA comes as a

FIGURE 6.2 General principles of decision analysis in analytical chemistry.

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6. Full blown green metrics

practical statistical tool to evaluate standard analytical methods and their selection for a particular analysis. If MCDA is fed with input criteria for cost of reagents, specific analytical parameters and lack or some analytical instruments, it offers practical solutions during evaluating greenness quotient of the procedure. One of the current pressing challenges in analytical technique is determination of microplastics in different matrices and choosing the greener method of analysis. If one applies GAC principles and our current state of analytical instrumentation, it is possible to directly analyse microplastics rather than extracting them from matrices, though not possible due to complexity of matrices itself. Bellasi et al. [41] reported that microscopic imaging techniques are greener techniques that are obvious due to fewer use of reagents during sample testing. The work in the direction to optimize a greener route to microplastic analysis is elusive and hence, it is recommended to find solution to this problem. Some of the possible solutions for ecofriendly microplastic determination are microscopy, thermal analysis, and vibrational spectroscopy and automation techniques.

6.3.2 March towards miniaturization Analytical laboratories are changing and conventional instruments are downscaled to miniaturized devices. The key drivers to miniaturized analytical instruments are portability, reduced laboratory bench-space, superior analytical performance, faster analysis and energy-power economics. Apart from these driving factors, automation and environment sustainability are achieved using miniature devices. A typical microgas chromatography (μ-GC) system comprises of microcolumn, micropumps, injector and detector that allows onsite analysis of various environmental samples. When bench-top GC is miniaturized to μ-GC systems, energy consumption reduces drastically, but it comes with an issue of sensitivity and detection limits. The problem of detection limits in μ-GC systems is attributed to change of detection systems. This problem is circumvented by employing a preconcentration step to achieve sub-ppb levels of analyte detection. Preconcentration refers to increasing analyte concentration such that it is detectable and performed prior to injecting them onto the microcolumn. A critical review on μ-preconcentrators in portable GCs proposed a new analytical figure of merit called normalized preconcentration efficacy to determine device performance [42]. The next popular analytical technique is HPLC that commands ˇ extensive use of solvents as mobile phases. Slais and Preussler [43] reported the first-ever gradient μ-HPLC system to separate mixture of phenols with a reproducibility of retention times at 0.2%
0.3%. Chatzimichail et al. [44] demonstrated first-ever portable HPLC-based system equipped with a broadband spectral detector capable of fingerprinting polycyclic hydrocarbons using their absorption spectral profiles. Their method utilized statistical and automated unsupervised model to detect and isolate peaks alongwith hidden peaks. As HPLC is known for its high solvent usage, most of the work towards greening the technique involves use of safer solvents. Acetonitrile, ethanol-water, acetone-water, water-buffer and pure ambient water are commonly employed as mobile phases in HPLC systems [45]. To avoid use of organic solvents, supercritical fluids (SCFs) such as SC-CO2 and SC-H2O also made their way as mobile phases. However, these solvents demand higher energy usage and at times require use of noxious methanol [46] or alternate

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azeotropic ethanol [47] as modifier solvents. These demerits lead to utilizing other miniaturized systems such as capillary [48] and micellar HPLC-based [49] instruments. As analytes are of diverse nature, HPLC instruments are routinely hyphenated with advanced spectroscopic detection systems to analyze complex mixtures. HPLC-mass spectrometry (MS) is a versatile technique that has various applications in chemical analysis and metabolomics. If we imagine miniature mass spectrometry, it requires downscaling bulky mass analysers and vacuum systems equipped with ambient ionization techniques. When the seminal work on MS miniaturization was demonstrated, it was primarily to utilize the system in forensic investigation, medical diagnostics, environmental monitoring, space exploration and industrial process control [50]. These applications require portable devices, and rapid analysis and green approach was not in the analytical chemists’ minds at that time. Korvink et al. [51] described mini-nuclear magnetic resonance (NMR) and provided modified NMR equations relating to miniaturised systems. Another emerging technique is a smartphone-based analytical biosensor having potential applications in medicine, biochemistry and environmental analysis. Schlesner et al. [52] demonstrated the rapid analysis of sugar content in soft and tonic drinks using smartphone-based colorimetric method. Their methods were validated using chemometrics and demonstrated high sample throughput of 444 samples per hour and utilised GAPI metric tool to their method. These portable greener techniques allow reduced sample volumes, potential for automation, easy to handle, shorter response times and enhanced analytical performance. It is envisioned that as we are moving from bench-top to hand-held devices through miniaturization, GAC principles are achievable without compromise on robustness of present-day analytical techniques.

6.3.3 Bio-based solvents in synthesis and analysis In synthetic chemistry, solvent replacement is still baffling chemists. As discussed in Section 6.2.1 on the waste metrics for organic synthesis, it was clear that solvents are a major concern due to their waste generation index. Most of the organic synthesis necessitates usage of polar aprotic solvents that are now replaced by bio-based alternate solvents. Dimethylisosorbide, propylene carbonate, N-formylmorpholine, dihydrolevoglucosenone and N-butylepyrrolidinone are identified as potential greener solvents that can replace organic solvents. Next, a major challenge is to replace halogenated solvents that need an immediate attention of organic chemists. In analytical procedures, solventless approach and use of ionic liquids and SCFs have proven mettle, yet they suffer from serious limitations such as: 1. Solventless methods do not offer practicality in all analytical procedures. 2. SCFs require higher energies and complicated instruments. 3. Ionic liquids are incompatible solvents in partition chromatography due to higher viscosities that necessitates tuning the instrumentation and solvent parameters. To circumvent these problems, bio-based solvents are widely applied in analytical separation and extraction techniques. Ethanol, methanol, formic acid and acetone are routine solvents for extraction that can be obtained from lignocellulose feedstock [53]. In recent

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years, studies are proving that bio-based solvents are considered superior to conventional green solvents. For example, limonene, obtained as a by-product from citrus industries through azeotropic distillation, is considered as a green solvent. Veillet et al. [54] replaced toluene with limonene for moisture analysis in foods using Dean-Stark apparatus. However, this method compared hexane with limonene stating that hexane is a toxic solvent with no clear metrics, bringing us to square one on the problem. These methods demonstrate only marginal improvement in yields compared to toxic solvents with green metrics amiss to elucidate true greener solvent potential. Prat et al. [55] demonstrated CHEM21 solvent selection guide where limonene was ranked as a problematic solvent and toxic towards aquatic organisms. Apart from these disadvantages, limonene (bp 5 175.5 C) possesses higher boiling point than hexane (bp 5 68.7 C) and thus requires higher energy consumption during solvent recovery. By now, we are aware that solvents are a huge problem in chromatography. Acetonitrile and methanol are commonly employed as mobile phases in routine reversed phase HPLC analysis. Polypropylene carbonate is a green mobile phase in HPLC method that replaced acetonitrile in alprazolam and sertraline determination as combined dose [56]. Zhou et al. [57] performed microwave-based extraction of coumarins and flavones from plants efficiently using aqueous polyethylene glycol solution replacing methanol. 2-Methyloxolane (2MeOx) is another biosolvent employed to extract natural products and aromatic compounds from different substrates. Considered as a greener alternative solvent to THF, various applications of 2-MeOx are investigated in extraction and separation techniques. Ozturk et al. [58] demonstrated that 2-MeOx performed better at extracting limonene at about 40% efficiency from orange peel residues against hexane as a solvent. Claux et al. [59] evaluated 2-MeOx as a dry solvent and aqueous solution against hexane solvent to extract soybean oil. They demonstrated higher crude soybean oil extraction yields compared to hexane that were attributed to coextraction of isoflavones and phospholipids. Further, they also illustrated the linkage of using 2-MeOx to 11 goals of SDGs. Most of the analytical methods utilized biosolvents to obtain biologically active ingredients from plant sources. The utilization of biosolvents in analytical methods was more in extraction methods rather than as direct use in separation techniques. It must be noted that while selecting biosolvents as mobile phase in chromatography, it must not cause biosolvent impurities to elute along with major analytes. Overall, a high-purity biosolvent makes the process a daunting and an energy-intensive task, as it necessitates distilling biosolvents prior to its application.

6.4 Sustainability metrics At present, industrial attitudes towards environment have evolved beyond the strict concerns for compliance. Industrial metrics are designed to assess overall chemical processes being environmentally benign without any deviation from the productive yields. With current demands, environmental metrics must grow beyond analysing greenhouse gas (GHG) emissions and water pollution. The dire need to shift our focus from green metrics to sustainability metrics is of paramount importance. Sustainability metrics such as life cycle assessment, green aspiration levels, carbon footprints, energy and productivity

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metrics are some of the examples that take into account environment, economics and society for defining a “real green analytical method”. Some of the common sustainability metrics are discussed in this section. Global warming potential (GWP) is a metric proposed by Intergovernmental Panel on Climate Change [60] to calculate potency of GHGs relative to CO2 expressed as      NCmolecule NCCO2 GWP kgCO2 eq 5 (6.7) MW of the molecule MWCO2 where NC is the number of carbon atoms in a molecule and MW is the molecular weight. Global warming index (GWI) is expressed as: IGW 5 GWPm : Ozone depletion potential (ODP) is a numeric value expressing ability of volatile halogen compounds depleting stratospheric ozone in relation to CFC-11: X ODPðkgCFC 2 11 eqÞ 5 ODPi 3 mi (6.8) where ODPi refers to equivalency factor for substance, I (CFC-11 eq) and mi refers to emission substance [61]. To take into account tropospheric ozone, another metric is devised called photochemical ozone creation potential (POCP) expressed as follows [62]:   kgC2 H4 OIVOC (6.9) POCP 5 kgVOC OIethene where OIVOC and OIethene refer to ozone increments with volatile organic compounds (VOC) and ethene, respectively. Acidification potential (AP) is a metric for SO2 emissions, a known precursor for acid rains expressed as [63]:   α α 3 (6.10) AP kgSO2 eq 5 MW of agas MW of SO2 ; ð64:1Þ where the value 64.1 in the parenthesis is the molecular weight of SO2 and α value will be 2 due to H2SO4 formation. Acidification index (IAP) is obtained by multiplying acidification potential of by the emitted mass of the compound given as, IAP 5 AP 3 m. Eutrophication potential (EUP) is a measure of ability to enriched soil and water leading to excess algal blooms in aqueous systems and expressed as follows [64]: X EPi 3 mi (6.11) EUPðkgPO22 4 eqÞ 5 Abiotic depletion potential (ADP) calculates the risks of element depletion relative to antimony (Sb) expressed as follows [64]: XADPðTÞ (6.12) XADP where XADP is life cycle use of antimony and its equivalents per capita per year. The sustainable Sb allocation is calculated annually as YADP 5

XADPðTÞ 5

RSb 3 αADP worldpopulation 3 tsus

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(6.13)

124

6. Full blown green metrics

where RSb is recoverable resources of Sb, tsus is timescale for the sustainability assessment. Smog formation potential (SFP) is a measure of the ability of VOC to contribute to the ozone formation relative to the standard mixture of reactive gases (RG) expressed as follows [63]: SFP 5

MIR MIRRG

(6.14)

where MIR refers to maximum incremental reactivity of a compound. The smog formation index is depicted as ISF 5 SFP 3 m. These sustainability metrics provide a useful information to perform modelling studies of environmental issues.

6.5 Conclusions and future perspectives The overall green chemistry is possible with cumulative design of safe solvents, miniature instruments and incorporating sustainability metrics. Usually, chemists determine greenness of chemical process using developed green metrics such as AE, E factor, GAPI, AGREE, NEMI, etc. These metrics prove to be inefficient, if employed in a solitary manner. In organic synthesis, most of the literature reveals extensive use of oxidation methods using air or oxygen. Notably, these oxidants are relatively safe but conducted above flash points of organic reaction mixtures. This contradicts the basic premise of greenness as such processes are hazardous on industrial scale-up. Catalysis is a front-runner in greening organic synthesis in a commercial sense as most reactions are achieving kilogram scale of organic products. Based on our experience on catalysis, raw materials used in the reaction itself act as catalysts in chosen solvents. At times, even solvents act as a catalyst themselves. Many organic reactions are also promoted by rapid heating using microwave and ultrasound methods. Thus use of catalysts as an additional component in most cases is impractical. As the saying goes, “even a grain of sand if improves the situation, one must go for it”, seems to be the decision while using catalysis thereby achieving greenness. Metal-based catalysts are troublesome and are usually proposed to be replaced by enzyme catalysts. Industries are focusing on developing enzyme catalysts that are safe, sustainable, robust, recyclable and patentable. As we advocate on enzyme catalysts, it must be realized that green metrics are to be applied while assessing their greenness quotient. Water is an essential solvent for driving enzyme-mediated organic reactions. Hence, E factor and productivity metrics need to incorporate water factor when dealing with enzyme catalysis. It is argued that enzyme production consumes higher energy making it a less efficient choice for greener catalysis. This led to the genesis of E1 factor that reported huge energy consumption in a laboratory-scale fermentation process [65]. We discussed on green and statistical metrics utilized to improve greenness quotient of organic and analytical methods. It is realized that solvents are a problem in analytical methods, thereby biosolvents are critically considered. All these efforts are based on the premise of GAC principles. Recently, Nowak et al. [66] proposed white analytical chemistry to address the issue of lack of equal balance of greenness and efficiency of analytical

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Abbreviations

125

method that is presented by GAC principles. To conclude, some tough questions regarding green metrics and our reflections on the issues are as follows: 1. Reiterating Michel’s editorial on biofuels we ponder, “whether biofuels are greener and a sustainable approach”? [11]. 2. William H. Glaze ponders on green chemical reactions as, “only be assessed in the context of its scale-up, its application and its practice” [67]. “Do green metrics be practiced only to monitor industrial scale-up or for practice in laboratories”? 3. Winterton’s 12 additional principles led to genesis of 2003 original green chemistry principles [68] with an objective to solve engineering problems. “Do we need more principles besides green chemistry, green engineering and GAC to reach the goal”? As a whole, biofuels are not carbon neutral systems. It must incorporate green metrics to support their concept of environmental sustenance. Metrics such as carbon footprint, land use, GHG emissions and crop feedstock are essential parameters to be incorporated to measure greenness of biofuels. In true sense, energy, economics and productivity must not be compromised while designing greener methods to make it industrially relevant biofuel process. Reflecting on Glaze’s view, green and sustainability metrics are taken in totality both in laboratory and industrial scale. Particularly, AE and E factor have come a long way, even with criticisms of being a crude metric. Other metrics are similarly holding promise to understand sustainability of chemical processes. Finally, there is no dire need to formulate newer principles to achieve greenness of chemical processes. Green metrics are maturing and result in better understanding of designing sustainable industrial processes and their EI.

Abbreviations AHP CFC-11 E factor EI EPA FAIR FIA GAC GHGs GSK HDMA HPLC HMF IPCC LC LCA MCDA 2-MeOx µ-GC Ms MVS

analytical hierarchical process trichlorofluoromethane or freon-11 environmental factor environmental impact United States Environmental Protection Agency findable, accessible, interoperable, reusable flow injection analysis green analytical chemistry greenhouse gases GlaxoSmithKline hexamethylenediamine high performance liquid chromatography hydromethylfurfural intergovernmental panel on climate change liquid chromatography life cycle assessment multicriterial decision analysis 2-methyloxolane microgas chromatography mass spectrometry multivariate statistics

Green Chemistry Approaches to Environmental Sustainability

126 NMR PAHs PDBEs RP-HPLC SCFs SDGs THF TNT VOC WAC

6. Full blown green metrics

nuclear magnetic resonance polycyclic hydrocarbons polybrominated diphenyl ethers reversed-phase high performance liquid chromatography supercritical fluids sustainable development goals tetrahydrofuran 2,4,6
trinitrotoluene volatile organic compounds white analytical chemistry

References [1] T.P. Anastas, C.J. Warner, Green Chemistry: Theory and Practice, University Press, Oxford, 1998. [2] R.A. Sheldon, The E factor: fifteen years on, Green Chem. (2007) 1273
1283. Available from: https://doi. org/10.1039/B713736M. [3] A.B. Dros, O. Larue, A. Reimond, F.D. Campo, M. Pera-Titus, Hexamethylenediamine (HMDA) from fossilvs. bio-based routes: an economic and life cycle assessment comparative study, Green Chem. 17 (2015) 4760
4772. Available from: https://doi.org/10.1039/C5GC01549A. [4] J. Elkington, Accounting for the triple bottom line, Measuring Bus. Excell. 2 (3) (1998) 18
22. Available from: https://doi.org/10.1108/eb025539. [5] J.L. Tucker, M.M. Faul, Industrial research: drug companies must adopt green chemistry, Nature 534 (2016) 27
29. Available from: https://doi.org/10.1038/534027a. [6] B.M. Trost, The atom economy—a search for synthetic efficiency, Science 254 (1991) 1471
1477. Available from: https://doi.org/10.1126/science.1962206. [7] R.A. Sheldon, Organic synthesis: past, present and future, Chem. Ind. 23 (1992) 903
906. [8] D.J. Constable, A.D. Curzons, V.L. Cunningham, Metrics to ‘green’ chemistry—which are the best? Green Chem. 4 (2002) 521
527. Available from: https://doi.org/10.1039/B206169B. [9] T. Hudlicky, D.A. Frey, L. Koroniak, C.D. Claeboe, L.E. Brammer Jr., Toward a ‘reagent-free’ synthesis, Green Chem. 1 (1999) 57
59. Available from: https://doi.org/10.1039/A901397K. [10] A.J. Be´champ, De l’action des protosels de fer sur la nitronaphtaline et la nitrobenzine. Nouvelle me´thode de formation des bases organiques artificielles de Zinin, Annales de. Chimie et. de Phys. 42 (3) (1854) 186
196Retrieved 2022, from. Available from: https://gallica.bnf.fr/ark:/12148/bpt6k347830.image.f185. [11] H. Michel, The nonsense of biofuels, Angew. Chem. 51 (11) (2012) 2516
2518. Available from: https://doi. org/10.1002/anie.201200218. [12] F.R. Lawrence (1983, November 15). US Patent No. US4415754A. Retrieved 2022, from https://patents.google.com/patent/US4415754A/en. [13] G.J. Sunley, D.J. Watson, High productivity methanol carbonylation catalysis using iridium: the Cativat process for the manufacture of acetic acid, Catal. Today 58 (4) (2000) 293
307. Available from: https://doi.org/ 10.1016/S0920-5861(00)00263-7. [14] V. Escande, C.H. Lam, P. Coish, P.T. Anastas, Heterogeneous sodium-manganese oxide catalyzed aerobic oxidative cleavage of 1,2-diols, Angew. Chem. 56 (32) (2017) 9561
9565. Available from: https://doi.org/ 10.1002/anie.201705934. [15] A. Harsanyi, A. Conte, L. Pichon, A. Rabion, S. Grenier, G. Sandford, One-step continuous flow synthesis of antifungal WHO essential medicine flucytosine using fluorine, Org. Process. Res. Dev. 21 (2) (2017) 273
276. Available from: https://doi.org/10.1021/acs.oprd.6b00420. [16] X. Lang, W. Ma, Y. Zhao, C. Chen, H. Ji, J. Zhao, Visible-light-induced selective photocatalytic aerobic oxidation of amines into imines on TiO2, Chem. - A Eur. J. 18 (9) (2012) 2624
2631. Available from: https://doi. org/10.1002/chem.201102779. [17] D.S. Lee, M. Sharabi, R. Jefferson-Loveday, S.J. Pickering, M. Poliakoff, M.W. George, Scalable continuous vortex reactor for gram to kilo scale for UV and visible photochemistry, Organic Process Res. Development 24 (2020) 201
206. Available from: https://doi.org/10.1021/acs.oprd.9b00475.

Green Chemistry Approaches to Environmental Sustainability

References

127

[18] T. Wan, Z. Wen, G. Laudadio, L. Capaldo, R. Lammers, J. Rinco´n, et al., Accelerated and scalable C(sp3)
H amination via decatungstate photocatalysis using a flow photoreactor equipped with high-intensity LEDs, ACS Cent. Sci. 8 (1) (2022) 51
56. Available from: https://doi.org/10.1021/acscentsci.1c01109. [19] K.C. Harper, E.-X. Zhang, Z. Liu, T. Grieme, T.B. Towne, D.J. Mack, et al., Commercial-scale visible light trifluoromethylation of 2-chlorothiophenol using CF3I gas, Org. Process. Res. Dev. 26 (2) (2022) 404
412. Available from: https://doi.org/10.1021/acs.oprd.1c00436. [20] A. Gałuszka, Z. Migaszewski, J. Namie´snik, The 12 principles of green analytical chemistry and the SIGNIFICANCE mnemonic of green analytical practices, TrAC. Trends Anal. Chem. 50 (2013) 78
84. Available from: https://doi.org/10.1016/j.trac.2013.04.010. [21] H. Malissa In E. Roth, Euroanalysis VI. Reviews on Analytical Chemistry (pp. 49
64). Paris, France: Les editions de physique, 1987. [22] M. Guardia, K.D. Khalaf, V. Carbonell, A. Morales-Rubio, Clean analytical method for the determination of propoxur, Anal. Chim. Acta 308 (1995) 462
468. Available from: https://doi.org/10.1016/0003-2670(94) 00625-V. [23] E. Zagatto, A. Vida, P. Worsfold Flow analysis | Overview (3 ed.). Elsevier, 2016. Available from: https:// doi.org/10.1016/B978-0-12-409547-2.12202-4 [24] W.R. Melchert, B.F. Reis, F.R. Rocha, Green chemistry and the evolution of flow analysis. A review, Anal. Chim. Acta 714 (2012) 8
19. Available from: https://doi.org/10.1016/j.aca.2011.11.044. [25] NEMI, National Environmental Methods Index. US Environmental Protection Agency; United States Geological Survey; National Water Quality Monitoring Council;. (2022). Retrieved June 5, 2022, from https://www.nemi.gov/about/. [26] M. Guardia, S. Armenta, Practical consequences of green analytical chemistry, in: Ml Guardia, S. Armenta (Eds.), Comprehensive Analytical Chemistry, Vol. 57, Elsevier, Amsterdam, 2011, pp. 219
232. Available from: http://doi.org/10.1016/B978-0-444-53709-6.00010-0. [27] A. Gałuszka, Z.M. Migaszewski, P. Konieczka, J. Namie´snik, Analytical Eco-Scale for assessing the greenness of analytical procedures, TrAC. Trends Anal. Chem. 37 (2012) 61
72. Available from: https://doi.org/ 10.1016/j.trac.2012.03.013. [28] S. Armenta, Md Guardia, J. Namiesnik, Green microextraction, in: M. Valca´rcel, S. Ca´rdenas, R. Lucena (Eds.), Analytical Microextraction Techniques, 1 ed., Bentham Science, Spain, 2015, pp. 3
27. Available from: http://doi.org/10.2174/9781681083797117010004. [29] J. Płotka-Wasylka, A new tool for the evaluation of the analytical procedure: Green Analytical Procedure Index, Talanta 181 (2018) 204
209. Available from: https://doi.org/10.1016/j.talanta.2018.01.013. [30] F. Pena-Pereira, W. Wojnowski, M. Tobiszewski, AGREE—Analytical GREEnness Metric Approach and Software, Anal. Chem. 92 (14) (2020) 10076
10082. Available from: https://doi.org/10.1021/acs.analchem.0c01887. [31] R. Hartman, R. Helmy, M. Al-Sayah, C.J. Welch, Analytical Method Volume Intensity (AMVI): a green chemistry metric for HPLC methodology in the pharmaceutical industry, Green Chem. 13 (2011) 934
939. Available from: https://doi.org/10.1039/C0GC00524J. [32] Y. Gaber, U. To¨rnvall, M.A. Kumar, M.A. Amin, R. Hatti-Kaul, HPLC-EAT (Environmental Assessment Tool): a tool for profiling safety, health and environmental impacts of liquid chromatography methods, Green Chem. 13 (2011) 2021
2025. Available from: https://doi.org/10.1039/C0GC00667J. [33] G. Koller, U. Fischer, K. Hungerbu¨hler, Assessing Safety, Health, and Environmental Impact Early during Process Development, Ind. Eng. Chem. Res. 39 (4) (2000) 960
972. Available from: https://doi.org/10.1021/ ie990669i. [34] K.F. Pun, I.K. Hui, An analytical hierarchy process assessment of the ISO 14001 environmental management system, Integr. Manuf. Syst. 12 (5) (2001) 333
345. Available from: https://doi.org/10.1108/EUM0000000005711. [35] M. Behzadian, R.B. Kazemzadeh, A. Albadvi, M. Aghdasi, PROMETHEE: a comprehensive literature review on methodologies and applications, Eur. J. Operat. Res. 200 (1) (2010) 198
215. Available from: https://doi. org/10.1016/j.ejor.2009.01.021. [36] M. Behzadian, S.K. Otaghsara, M. Yazdani, J. Ignatius, A state-of the-art survey of TOPSIS applications, Expert. Syst. Appl. 39 (17) (2012) 13051
13069. Available from: https://doi.org/10.1016/j.eswa.2012.05.056. [37] B. Apperl, J. Andreu, T.P. Karjalainen, M. Pulido-Velazquez, Contribution of the Multi Attribute Value Theory to conflict resolution in groundwater management. Application to the Mancha Oriental groundwater

Green Chemistry Approaches to Environmental Sustainability

128

[38] [39]

[40] [41]

[42]

[43] [44]

[45]

[46]

[47]

[48]

[49]

[50]

[51] [52]

[53] [54]

[55]

[56]

6. Full blown green metrics

system, Spain, Hydrol. Earth Syst. Sci. Discuss. 11 (2014) 10235
10271. Available from: https://doi.org/ 10.5194/hessd-11-10235-2014. K. Govindan, M.B. Jepsen, ELECTRE: a comprehensive literature review on methodologies and applications, Eur. J. Operat. Res. 250 (1) (2016) 1
29. Available from: https://doi.org/10.1016/j.ejor.2015.07.019. M. Maimoun, K. Madani, D. Reinhart, Multi-level multi-criteria analysis of alternative fuels for waste collection vehicles in the United States, Sci. Total Environ. 550 (2016) 349
361. Available from: https://doi.org/ 10.1016/j.scitotenv.2015.12.154. S.J. Dee, B. Cox, R. Ogle, M. Walters, Evaluating inherently safer design with multiattribute utility theory, Process. Saf. Prog. 38 (3) (2019) e12022. Available from: https://doi.org/10.1002/prs.12022. A. Bellasi, G. Binda, A. Pozzi, G. Boldrocchi, R. Bettinetti, The extraction of microplastics from sediments: an overview of existing methods and the proposal of a new and green alternative, Chemosphere 278 (2021) 130357. Available from: https://doi.org/10.1016/j.chemosphere.2021.130357. I. Lara-Ibeas, A. Rodrı´guez Cuevas, S. Le Calve´, Recent developments and trends in miniaturized gas preconcentrators for portable gas chromatography systems: a review, Sens. Actuators B: Chem. 346 (2021) 130449. Available from: https://doi.org/10.1016/j.snb.2021.130449. ˇ A. Slais, V. Preussler, A simple miniature gradient system for micro-HPLC, J. High. Resolut. Chromatogr. 10 (2) (1987) 82
85. Available from: https://doi.org/10.1002/jhrc.1240100206. S. Chatzimichail, F. Rahimi, A. Saifuddin, A.J. Surman, S.D. Taylor-Robinson, A. Salehi-Reyhani, Handportable HPLC with broadband spectral detection enables analysis of complex polycyclic aromatic hydrocarbon mixtures, Commun. Chem. 4 (2021). Available from: https://doi.org/10.1038/s42004-021-00457-7. L.O. Duarte, B. Ferreira, G.R. Silva, A.J. Ipo´lito, F.M. de Oliveira, Validated green phenyl reversed-phase LC method using ethanol to determine MDMA in seized ecstasy tablets, J. Liq. Chromatogr. Relat. Technol. (2020) 761
769. Available from: https://doi.org/10.1080/10826076.2020.1811725. S.H. Page, S.R. Goates, M.L. Lee, Methanol/CO2 phase behavior in supercritical fluid chromatography and extraction, J. Supercrit. Fluids 4 (2) (1991) 109
117. Available from: https://doi.org/10.1016/0896-8446(91) 90038-8. D. Roy, M. Wahab, M. Talebi, D.W. Armstrong, Replacing methanol with azeotropic ethanol as the cosolvent for improved chiral separations with supercritical fluid chromatography (SFC), Green Chem. 22 (2020) 1249
1257. Available from: https://doi.org/10.1039/C9GC04207E. S.C. Lam, L.J. Coates, M. Hemida, V. Gupta, P.R. Haddad, M. Macka, et al., Miniature and fully portable gradient capillary liquid chromatograph, Anal. Chim. Acta 1101 (2020) 199
210. Available from: https://doi.org/10.1016/j.aca.2019.12.014. E. Patyra, K. Kwiatek, Analytical capabilities of micellar liquid chromatography and application to residue and contaminant analysis: a review, J. Sep. Sci. 44 (11) (2021) 2206
2220. Available from: https://doi.org/ 10.1002/jssc.202001261. A. Malcolm, S. Wright, R.R. Syms, R.W. Moseley, S. O’Prey, N. Dash, et al., A miniature mass spectrometer for liquid chromatography applications, Rapid Commun. Mass. Spectrometry 25 (21) (2011) 3281
3288. Available from: https://doi.org/10.1002/rcm.5230. J.G. Korvink, N. MacKinnon, V. Badilita, M. Jouda, “Small is beautiful” in NMR, J. Magn. Reson. 306 (2019) 112
117. Available from: https://doi.org/10.1016/j.jmr.2019.07.012. S.K. Schlesner, M. Voss, G.A. Helfer, A.B. Costa, A.J. Cichoski, R. Wagner, et al., Smartphone-based miniaturized, green and rapid methods for the colorimetric determination of sugar in soft drinks, Green Anal. Chem. 1 (2022) 100003. Available from: https://doi.org/10.1016/j.greeac.2022.100003. H.H. Khoo, W.L. Ee, V. Isoni, Bio-chemicals from lignocellulose feedstock: sustainability, LCA and the green conundrum, Green Chem. 18 (2016) 1912
1922. Available from: https://doi.org/10.1039/C5GC02065D. S. Veillet, V. Tomao, K. Ruiz, F. Chemat, Green procedure using limonene in the Dean
Stark apparatus for moisture determination in food products, Anal. Chim. Acta 674 (1) (2010) 49
52. Available from: https:// doi.org/10.1016/j.aca.2010.06.009. D. Prat, A. Wells, J. Hayler, H. Sneddon, C.R. McElroy, S. Abou-Shehada, et al., CHEM21 selection guide of classical- and less classical-solvents, Green Chem. 18 (2016) 288
296. Available from: https://doi.org/ 10.1039/C5GC01008J. V. Namboodiry, S. Bhoir, P. Verma, S. Mishra, A. Bhagwat, Replacement of acetonitrile by mixtures of propylene carbonate and methanol as organic modifier in mobile phases For RPLC separation mechanism:

Green Chemistry Approaches to Environmental Sustainability

References

[57]

[58]

[59]

[60]

[61]

[62]

[63]

[64]

[65]

[66]

[67] [68]

129

application to the assay of Alprazolam and Sertraline in combined pharmaceutical formulations, J. Liq. Chromatogr. Relat. Technol. 35 (18) (2012) 2643
2654. Available from: https://doi.org/10.1080/ 10826076.2011.637273. T. Zhou, X. Xiao, G. Li, Z.-w Cai, Study of polyethylene glycol as a green solvent in the microwave-assisted extraction of flavone and coumarin compounds from medicinal plants, J. Chromatogr. A 1218 (23) (2011) 3608
3615. Available from: https://doi.org/10.1016/j.chroma.2011.04.031. B. Ozturk, J. Winterburn, M. Gonzalez-Miquel, Orange peel waste valorisation through limonene extraction using bio-based solvents, Biochem. Eng. J. 151 (2019) 107298. Available from: https://doi.org/10.1016/j. bej.2019.107298. O. Claux, V. Rapinel, P. Goupy, N. Patouillard, M.A. Vian, L. Jacques, et al., Dry and aqueous 2-Methyloxolane as green solvents for simultaneous production of soybean oil and defatted meal, ACS Sustain. Chem. Eng. 9 (21) (2021) 7211
7223. Available from: https://doi.org/10.1021/acssuschemeng.0c09252. J.T. Houghton, B.A. Callander, S.K. Varney, The 1992 IPCC Supplement: Scientific Assessment, Cambridge University Press, Cambridge, 1992Retrieved 2022, from. Available from: https://www.ipcc.ch/report/climate-change-1992-the-supplementary-report-to-the-ipcc-scientific-assessment/. World Meteorological Organization. Ozone Deplection and Chlorine Loading Potential, Scientific Assessment of Ozone Depletion, Global Ozone Research and Monitoring Project-Report No#25. Corporate, Geneva, Switzerland, 1992. R.G. Derwent, M.E. Jenkin, Hydrocarbons and the long-range transport of ozone and pan across Europe, Atmos. Environ. Part A Gen. Top. 25 (8) (1991) 1661
1678. Available from: https://doi.org/10.1016/09601686(91)90025-3. R. Heijungs, J. Guine´e, G. Huppes, H.A. Lankreijer, H.A. Udo A Haes, W. Sleeswijk, et al., Environmental Life Cycle Assessment of Products, Chapman & Hall, Leiden, The Netherlands, 1992. Accessed 3rd September 2022. K. Hacatoglu, A Systems Approach to Assessing the Sustainability of Hybrid Community (Ph.D. thesis), University of Ontario Institute of Technology, Oshawa, 2014. Available from: http://hdl.handle.net/10155/ 472. (accessed 03.08.22). F. Tieves, F. Tonin, E. Ferna´ndez, J.M. Robbins, B. Bommarius, A.S. Bommarius, et al., Energising the E-factor: the E 1 -factor, Tetrahedron 75 (10) (2019) 1311
1314. Available from: https://doi.org/10.1016/j. tet.2019.01.065. P.M. Nowak, R. Wietecha-Posłuszny, J. Pawliszyn, White Analytical Chemistry: an approach to reconcile the principles of Green Analytical Chemistry and functionality, TrAC. Trends Anal. Chem. 138 (2021) 116223. Available from: https://doi.org/10.1016/j.trac.2021.116223. W.H. Glaze, Sustainability engineering and green chemistry, Environ. Sci. & Technol. 34 (21) (2000) 449A. Available from: https://doi.org/10.1021/es003465y. N. Winterton, Twelve more green chemistry principles, Green. Chem. 3 (2001) G73
G81. Available from: https://doi.org/10.1039/B110187K.

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C H A P T E R

7 Green anthrosphere through industrial ecology Manik Devgan1, Arshdeep Kaur1, Anuj Choudhary2, Radhika Sharma3, Harmanjot Kaur4 and Sahil Mehta5 1

Department of Plant Breeding and Genetics, Punjab Agricultural University, Ludhiana, Punjab, India 2Department of Biology and Environmental Sciences, CSKHPKV, Palampur, Himachal Pradesh, India 3Department of Soil Science, Punjab Agricultural University, Ludhiana, Punjab, India 4Department of Botany, Punjab Agricultural University, Ludhiana, Punjab, India 5 Department of Botany, Hansraj College, University of Delhi, New Delhi, Delhi, India

7.1 Introduction Anthrosphere is the part of the environment modified or made by humans and employed for their activities. The term was first implemented by Eduard Suess in the 19th century. It consists of highways, buildings, railroads, parking lots, vehicles and aircraft that people make and evolve continuously and are modified by the earth’s biosphere. All human activities have shown high relevance to global-level change. Human and environmental interactions have been elucidated due to the researcher’s activities in several related fields, which usually fall within the single discipline’s boundaries and always below the global level [1,2]. Anthrosphere is composed of structures and devices created and operated by human activities. Because of its significant effects on the majority of environmental phenomena, the anthroposphere is regarded as one of the important environmental spheres. The prodigy of the human sphere is recently introduced as the earth has transitioned from a nonindustrialized to an intensive industrial epoch. During recent years particularly with the development of industrial mechanization, fossil fuels, large machines, mining, urbanization, etc., a massive environmental impact is being induced by the prevailing anthrosphere created by human activities. Over the centuries, we have observed significant pollution emissions that are a direct result of human activities. For instance, sulphur dioxide is a pollutant produced in the anthrosphere by industrial actions such as the combustion of coal, mining, vehicular emissions, etc. SO2 is

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transported into the atmosphere and oxidized by photochemical and chemical processes to form unwanted sulphuric acid. Similarly, NxO (nitrous oxides) emissions have significantly increased over the past quartile due to regular vehicle emissions, agricultural activities such as fertilizer inputs, industries, etc. [3]. Sulphuric acid and nitrous acids fall as acidic precipitate and cause toxic effects on the trees and plants of the biosphere. It is carried by the runoff stream of rainwater in the hydrosphere of a lake or ocean and eventually it is stored in the water in solution or can be precipitated to solid sulphates and again entered the geosphere [4 6]. Paul Crutzen (prize-winning atmospheric chemist) has argued the transition of the Holocene geological epoch on Earth to a new kind known as Anthropocene. It is because human activities are quite significant to impact the earth’s environment by altering the fundamental chemistry, biology and physics [7,8]. The activity in the anthrosphere is causing detrimental stable changes and directing them toward a state of challenge through a permanent change in the global climate. During most of its time on Earth, humankind has made a lesser impact on the planet and its numerous and scattered anthrospheric artifacts, such as simple tents or huts, clearings of some forest for growing their food, rested in the long historical timeline with no impact on the global level [9]. The drastic changes are made by the development and evolution in the industrial sector and especially in recent decades where humans have made a significant contribution by enhancing the number of structures and their derived forms [10]. This has led to maximum modification in the environmental spheres, mainly the geosphere. Therefore the anthrosphere has developed the reputation of a separate sphere with influence on the environment. Developing an anthrosphere that coexists harmoniously with the other life spheres without impairing their integrity is the main factor driving scientists to study it in detail. The term “anthrosphere” refers to the totality of human activities, and since these activities have proven to be harmful, why not manipulate human activities to produce an environment that harmoniously coerces with other life spheres? The creation of “GREEN ANTHROSPHERE” is one strategy. This chapter’s objective is to propose the idea of the “Green Anthrosphere”, along with its methodologies, framework and proposal for a “GREEN ECONOMY ARCHETYPE” for future use.

7.2 Infrastructure and sociosphere of anthrosphere Infrastructure can be considered as the defining characteristic of an anthrosphere. In fact, infrastructure is the “vertebra” that supports society. Every successful society has a well-established physical as well as regulatory infrastructure. Let’s imagine that infrastructure functions like the operating system of a computer, which essentially means that every environmental activity involves and is processed by infrastructure, that is, the anthroposphere’s infrastructure regulates a variety of activities, including the gathering and processing of raw materials, their transformation into manufactured goods and their distribution. And just like a timely software update, viability and timely modernization of infrastructure according to current suitability is important for a sustainable anthrosphere to exist [11,12]. Infrastructure can help modify the connection between the anthrosphere and four spheres, that is, biosphere, lithosphere, hydrosphere and atmosphere. Over the

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past two centuries, human activities including industrial, military and agricultural infrastructures in the anthrosphere have strongly degraded the quality of the other four spheres, particularly the atmosphere and lithosphere [13,14]. Up until now, a major proportion of infrastructure has been devoted to obstruction of natural balance, which is eventually a long-term losing endeavour. Carbon emissions from the anthrosphere pose a serious threat that can alter the ecological balance in the biosphere by leading to global warming. Similarly, overgrazing, deforestations and other activities like shifting cultivations degrade the natural infrastructure of an area [15]. The damage to infrastructure by human activities such as misuse, neglect and improper techniques is another major issue at the social level that needs to be addressed. Outdated or damaged components of infrastructure lead to the deterioration of the sociosphere and have a major ill effect on several environment-related phenomena [16]. Consider the example of late 20th-century air conditioners and refrigerators which released harmful chlorofluorocarbons that depleted the ozone layer and therefore, damaged atmosphere integrity which ultimately harms human health [17]. These anthrospheric activities particularly due to degraded infrastructure interfere with the proper functioning of the environment that could be subjected to catastrophic failure. Modifying the present infrastructure to “future-proof” the environment and improve environmental quality for the benefit of humans is an enormous task ahead of us. This change requires institutional, architectural and scientific integrations that are primarily environment friendly. The institutional change includes environmental laws, rules and regulations that need to be introduced in society that can teach people about threats anthrospheric activities impose on the environment [18]. As far as the architectural and scientific changes are concerned, these can be dealt with through the adoption of ecofriendly technological innovations, for instance, the introduction of the concept of renewable energy in urban and rural areas. Sensors for monitoring carbon emissions, temperature fluctuations and other parameters can help in understanding the effect of various currently used components in damaging anthrosphere infrastructure [19]. A part and parcel of this infrastructure are nonphysical, that is, composed of laws, rules and regulations, guidelines, and operational procedures coordinated through human society, these constitute “the sociosphere”. This aspect is the main modulator of the anthrosphere, and the remote controlling this sphere is driven by one battery: ECONOMY. The economy can be considered to be held responsible for irregularity with sustainable development. The economic concept introduces the terms of financial and materialistic possession which leads to environmental manipulation. Such strategies are unacceptably taxing on the natural resources of the earth and its support systems. The imbalance that arises from this predicament has been sought to be managed through two approaches: first is through resource restriction and second through equal economic growth and care for the earth, that is, green economy (GE) [20]. Amidst the present situation, changing harmful industrial inputs currently in use to ecofriendly goods can help solve a plethora of environmentrelated issues such as pollution, metal toxicity, corrosive and radioactive elements, biodiversity loss, chemical inputs, etc. Transforming the present industrial institution in the world to environment-friendly industrial machinery through understanding and use of industrial ecology (IE) offers a practical solution to the majority of ecological disturbances [18,21].

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7.3 Impact of IE on the environment The early anthrosphere created preindustrial era caused minimum environmental degradation to other spheres of life due to smooth integration and lesser exploitation. The anthrosphere preindustrial era was itself a component of natural ecosystems. With the introduction of new technologies and the establishment of industrial civilizations, humans advanced to a new age with hardly any regard for environmental balance [22,23]. This resulted in a severe ecological disturbance leading to corruption in the present environmental machinery. A massive release of pollutants with no pretreatment or precautionary measures resulted in the introduction of different forms of pollution, predominantly, air and water pollution. This degradation was not even considered before the mid-20th century and countries competed with each other for technological supremacy. Moreover, the present infrastructure on which society operates is not sustainable enough to support ongoing operations for the future [24]. Significant attempts have been undertaken to mitigate industrial practices having negative environmental effects. These include source treatment, safe dumping, bioremediation, etc., which are based on “end-of-pipe” approaches, that is, lack any proper flow and work in a closed loop. So far, the majority of industries follow this linear production system, that is, operate individually and follow a competitive approach with other industries rather than co-functioning [25,26]. What we need is crosssectional interaction which forms an open cycle and specialized industries in each product functioning at each step of the ecological cycle. This ecological cycle will lay the foundation for IE. According to this novel viewpoint, industrial complexes ought to be constructed in such a way that they closely resemble the ecosystem of the natural world. IE is a specialized division of ecology that aims to transform this linear production system into a circular or cyclical production system that interconnects industries with each other through the introduction of practically efficient and ecofriendly approaches [27]. IE is basically a component of the GE that works in a paradigm with industrial symbiosis (IS) and a clean development mechanism (CDM). IE operating within groups of organizations that share resources and by-products, minimizing waste to the farthest extent possible illustrates IS [28]. IE firmly interconnects several important components required in functionally sound industries together, including time, space and economy. IE follows a holistic approach and focuses on all enterprises rather than focusing on individual firms; moreover, it considers the total impact of the system on input, energy consumption for processing, and output of pollution and waste followed by by-product generation. Similarly, IE operates on a CDM, that is, minimum waste, no to little pollution and circulation of by-products to minimize wastage. Properly working IE can have several positive impacts: 1. 2. 3. 4. 5. 6.

Balanced industrial input and output [29] Improved efficiency for industrial processes [30] Completely harmless and recyclable end product [31] Enhanced corporate image [20] Less environmental degradation [32] Cost savings and more income generation [33].

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So far, IE projects have been successfully demonstrated in technology and innovation parks [34,35], cities [36,37] as well as at national levels [38]. Industrial atmospheric emissions have been decreasing markedly in recent years as a result of improved technologies, more stringent regulations and increased awareness about atmospheric emissions. One such example of successfully implemented IE is the Kalundborg system Netherlands [39]. However, this system was not planned initially and developed spontaneously by the interconnection between several enterprises for resource exchange. For instance, willingness to share assets for mutual benefits, that is, simultaneous use of water resources by different industries; use of surface water (Lake Tisse) instead of groundwater resources, surface water (from the municipality of Kolundborg) with cooling water [at Novozymes (fermentary)] and cooling water (used in DONG energy power station) with wastewater (of Statoil refinery). However, currently persisting IE in the anthrosphere has several ill effects on environmental spheres. One of the most obvious is that on the atmosphere, particularly due to air pollution and carbon emissions [40]. Excessive air pollutants released by human activities such as industrial smoke, vehicular emissions, fossil fuel burning, etc., include CO, NO2, SOX, O3, etc. These gases accumulate in the atmosphere and are responsible for the greenhouse effect, global warming, acid rain, ozone depletion and several others [41]. Some tropical nations adopt “slash and burn” farming methods, which release greenhouse gases into the atmosphere. The negative impacts of IE extend to other spheres as well. The geosphere has been seriously deteriorated by activities such as coal mining, waste dumping, leaching of toxic metals, etc., over the past decades [42]. Similarly, untreated sewage from industrial and municipal waste has damaged the hydrosphere to an immeasurable extent. Several actions must be taken to alter the ongoing IE and reduce its negative impacts on the environment [40]. One aspect that has major implications for industrial applications is chemical science. The majority of produced goods and products of industries are chemical based. The majority of everyday goods, including pharmaceuticals, agricultural inputs like fertilizers, pesticides, food safeners and processing, are products of chemical science. Unfortunately, the practice of chemical inputs has been far above the threshold levels and has led to environmental deterioration. Shifting from lethal chemical practices to environmental friendliness direction requires certain principle adaptations. This branch of green anthrosphere is termed as “GREEN CHEMISTRY”.

7.4 Green chemistry and IE The term “green chemistry” refers to the development of chemical processes and products that limit the consumption and production of hazardous chemicals [43]. Green chemistry deals with the reduction or elimination of hazardous materials released from chemical processes through the introduction of new designs and replacements. Careful planning and precise design to reduce adverse consequences of harmful chemical reactions is the basic characteristic of green chemistry. When it comes to reducing chemical use in industry, the issue is not how much to cut back but rather how to create chemicals that are necessary for a sustainable civilization, and have manageable natures, ecofriendly traits and nonpolluting

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manufacturing [44]. Only through proper designing one can gain synergies—not merely trade-offs. The two most common simultaneous approaches for the reduction of chemical use in IE followed in green chemistry are risk pruning and green chemicals.

7.4.1 Risk pruning This approach focuses on reducing the toxicity effects of chemical processes functioning currently in industries by opting for techniques less dangerous to workers and less harmful to the environment. This branch deals with hazard reduction that arises either from controlled chemical processes or uncontrolled accidental leakage. Understanding the origin and nature of these hazards is an essential component of hazard reduction. One of the primary focuses of hazard reduction is the reduction of toxic waste or end products, including heavy metals, VOCs (volatile organic compounds), lipid-soluble organic solvents and corrosive compounds.

7.4.2 Heavy metals These mostly include lead, arsenic, mercury, cadmium, etc. [45]. Heavy metals enter the ecosystem as highly stable and somewhat nondegradable contaminants [46]. Heavy metals released through industrial activities such as chemical manufacturing are released as waste products in the form of sewage leading to their accumulation on the surface or groundwater resources through seepage [47]. These highly affect river water quality in which they are released, thereby corrupting the natural water cycle and therefore, aquatic life. These compounds have major effects on human health and are carcinogenic in nature. Regular water quality monitoring is necessary for checking their content in waste dumping areas. Lin et al. [48] developed a two-electrode and four-electrode made up of platinum rods to detect the presence of lead and other heavy metals with zero false response.

7.4.3 Hydrocarbons This category of pollutants includes combustible organic carbon compounds that are lipid soluble and highly evaporative in nature such as VOCs, and PCBs (polychlorinated biphenyls) that are generally used as solvents in automobile industries. These organic substances enter the food chain through biomagnification [49]. Fumes emitted by such compounds cause respiratory problems and acute pneumonia. Jan et al. [50] developed IoTbased environmental sensor to detect the contamination of water by hydrocarbons, heavy metals and other parameters.

7.4.4 Corrosive compounds This category includes quality deteriorating compounds that are corrosive in nature for other metals and even biological beings. These substances are generally released in industrial smoke that later precipitates and causes acid rain. Silicate glasses are most commonly eroded by these acid rains [51]. These substances also damage the machinery in industries

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thereby affecting the industrial infrastructure [52]. The application of naturally derived corrosion inhibitors over synthetic corrosion inhibitors has several advantages including environmental friendliness, ecological acceptability, low cost, renewability, etc. Tiwari et al. [53] prepared a cost-effective ethyl acetate extract of Musa paradisica peels (EAEMPP) for steel corrosion prevention due to acidic conditions and observed that EAEMPP limits the rate of oxidative and reductive reaction on active metal sites. In another research, biodegradable human hair extract was found to have corrosion mitigation effects under 1 M HCl concentration [54]. Green chemistry focuses on the avoidance or elimination of the use of such substances from industries and promotes transforming to hazard-proof inputs.

7.4.5 Green chemicals This approach follows replacing the harmful chemicals used in chemical reactions with nature-friendly inputs. The most common chemical components used in industries include feedstocks, solvents, chemicals/reagents and catalysts. Replacing these components with less residual green solvents offers a viable solution. There are 12 basic principles of green chemistry given by Paul Anastas and John Warner in 1998 [55] (Table 7.1). Compounds that adhere to these principles during synthesis have certain characteristics that qualify them as “green chemicals”, such as 1. 2. 3. 4. 5. 6.

low in-flammability low toxicity absence of toxic environmentally dangerous constituents low bioaccumulation faster biodegradation less erratic nature.

7.4.6 Catalysts Catalysts are compounds that used for accelerating the rate of a particular chemical reaction. They play an important role in chemical reactions by saving energy as well as producing specific end products. However, these are metal based and when disposed have hazardous effects on the environment. The concept of biocatalysts in green chemistry is an available solution to this problem [65]. Biocatalysts are nothing but whole intact organisms or isolated enzymes used in place of toxic metal catalysts in industries. These substances in comparison to normal catalysts have more selectivity, rate of reaction, less cost, and low requirements such as ambient temperature and pressure suitability [60]. Practical application of biocatalysts in industries like organic dye industries that are very toxic to human health as well as the environment by use of biogenic silver nanoparticles has been quite successful [66,67]. Similarly, biocatalysts have been used in winemaking [68] as well as the use of endophytic fungi in steroid manufacturing and perfume industries has demonstrated their effectiveness [19,69]. Besides the use of biocatalysts, certain other catalysts could be used that successfully enhance the rate of reaction; these methods are enlisted in Table 7.2.

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TABLE 7.1 Twelve principles of green chemistry. Name

Ideology

Aim

Impact

Risks concerned Reference

Waste prevention

Refined resource use

Preventing waste generation

High

Low

Sheldon [56]

Atom economy

Enhanced energy efficiency

Effective utilization of input to obtain the maximum final product

High

High

Sharma et al. [57]

Maximum safety Hazard reduction

Generating substances with minimum toxicity and environmental hazard

High

Low

Li & Trost [58]

Cautious chemical synthesis

Hazard reduction

Avoiding hazardous chemical substances

High

Low

Sheldon [59]

Catalysis

Enhanced energy efficiency

Fastening rate of chemical reactions

High

Low

Anastas & Eghbali [60]

Safer solvent and Refined auxiliaries resource use

Development of ecofriendly solvents

High

Low

Bergman et al. [61]

Renewable feedstocks

Refined resource use

Biodegradable input for waste elimination

Medium Low

Ivankovic et al. [62]

Reducing derivatives

Refined resource use

Avoiding unnecessary chemical reagents High

Medium

Sheldon [59]

Energy efficiency Enhanced energy efficiency

Reducing energy consumption

High

High

Zhang et al. [63]

Designing for depletion

Hazard reduction

Easily degrading nontoxic by-products

Medium Low

Nendza et al. [64]

Real-time pollutant monitoring

Hazard reduction

Regular inspection of pollutant release from industries

High

Low

Sharma et al. [57]

Accidents prevention

Hazard reduction

Minimizing fatal chemical accidents

High

Low

Ivankovic et al. [62]

7.4.7 Feedstock These include the basic substrates upon which chemical reaction occurs, leading to its transformation into a product. Green chemistry practices involve the use of renewable or biodegradable feedstock in place of harmful chemicals so that the product generated can follow an “end of pipe” approach. For instance, use of bioethanol in place of petroleumbased chemicals that are used in textiles, plastics and rubber industries can reduce the excessive consumption of petroleum which is nonrenewable [74]. Similarly, the use of lactic acid polymers obtained from corn in blend with polyethylene for the synthesis of plastic bottles by Coca-Cola is another example of biodegradable feedstocks [75].

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TABLE 7.2 Strategies for enhancing green chemistry reactions. Catalysts

Befitting reactions

Advantage

Disadvantages

Reference

Microwaves

1. Biginelli reaction 2. Pechmann condensation reaction 3. Mannich reaction 4. Hosomi Sakurai reaction 5. Grignard reaction

1. Quicker reaction rate 2. Easy application 3. Increased selectivity

Bassyouni et al. [70]

Sonochemistry

1. 2. 3. 4.

1. 95% selectivity 2. Less heating effect 3. Enhanced reaction rate

Electrolysis

1. Reduction 2. Oxidation

1. High-energy efficiency 2. 100% atom economy 3. Highly adjustable 4. “Matter-free catalyst”

Photochemical reactions

1. Photoacylation 2. Photooxygenations

Photocatalysis

1. Second-generation TiO2 photocatalysts for oxidationreduction reactions 2. Sterilization reactions 3. Bombardment reactions

1. Reduced reaction steps 2. Suitable at ambient temperatures 3. Suitable for highly reactive species 4. Cheap 1. Ecoharmonious catalysts 2. Adjustable absorption spectrum 3. 100% clean energy

1. Requirement of safe microwave equipment 2. Continuous microwave irradiation demand 3. Marginal effect on some reactions 1. Varied intensity requirement 2. Low reproducibility rate 3. Requirement of proper energy flow 1. Continuous current inflow required 2. Not suitable for corrosion-prone metals 1. Equipment demand 2. Decreased reaction rate

Microbial reactions oxidation reactions Hydrogenation reactions Lignocellulosic biomass conversion

1. Limited suitability 2. Adjustments such as N2 surface doping

Chatel [71]

Manahan [11]

Oelgemo¨ller et al. [72]

Masakazu et al. [73]

7.4.8 Solvents Chemical solvents used in reactions lead to environmental and health problems. Green chemistry focuses on the replacement of such chemicals by fast-degrading, zero wastegenerating solvents derived from renewable biological sources [76]. These are more sustainable and available (benign solvents derived from renewable biological sources are being given preference due to their availability and sustainability [77,78]). Biomassderived solvents have been used in pharmaceutical companies because of their suitability and higher efficiencies, for instance, the use of solvents 2-MeTHF and gamma valerolactone instead of toxic acetone and ethyl acetate [78,79].

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7.4.9 Chemical/reagents The development and use of bioreagents/green reagents for monitoring harmful metals or elements in water is another approach for controlling the emission of hazardous substances in the environment [80]. These reagents offer high product selectivity and low implementation cost. Similarly, the use of lesser toxic reagents such as dimethyl carbonate in place of dimethyl sulphate that emits carbon monoxide gas is another green alternative solution [81]. The use of organic chemistry for cycloaddition reactions in the synthesis of valuable cyclic, heterocyclic polycyclic skeletons is one well-known example of the shift from inorganic to organic reactions and positive results. This field has also recently flourished in the pursuit of highly efficient asymmetric cycloadditions, C-H bond-activated cycloadditions, photoredox catalysis-cooperated cycloadditions and several unique reaction processes [82]. Green chemistry and IE cover parallel tracks and cannot be operated effectively without coercing each other. The role of green chemistry in establishing a nonpolluting and energy-efficient IE is very crucial. The practice of green chemistry can transform current IE into an increasingly safe, environmentally friendly and sustainable operation.

7.5 Industrial ecosystems design to reduce the environmental impact The present situation for the environment demands industrial products with as much minimum negative impact as possible. A successful industrial ecosystem is well-balanced and diverse, with various enterprises that circulate products between each other instead of discarding them as waste. A good industrial ecosystem represents a synergy between industries and therefore is a function of IS. Instant replacement of inputs being used by recycled or waste products is not a straightforward approach. This requires initial trials and effect estimations. For example, using recycled products in a certain ratio, for example, blending new metal and recycled metal in a ratio of 3:1 in electrical industries [83]. Similarly, the reuse of metal-oxide inorganic wastes, that is, “red mud” from the e-waste, Zn-C batteries and metal production industries to yield nanomaterials is a new approach [84]. Nanomaterials have a higher catalytic ability and their structure can be moulded as per requirement, particularly in electric batteries [85]. Fly ash as a constituent in cement in developed countries is also an example of successful IE between two different conglomerates, that is, cement industries and thermal plants [86]. Establishing such product synergies requires a good industrial ecosystem design. Anthrophere with well-designed industrial ecosystems emits much less harmful materials to the environment than conventional industrial systems [87]. For every industrial ecosystem, there are different platform coordinators or “actors” that are classified according to individual roles [88]. These include the following: 1. Resource providers: industry that provides input to other 2. Resource consumers: an industry that transforms the input or waste into resources 3. Intermediaries: facilitate business dealings between buyers and sellers

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141

4. Coordinators: person or parties responsible for communication between two or more industries. A successful industrial ecosystem is generally a good business ecosystem, that is, it should also focus on the economic growth of industries. However, the primary focus of the industrial ecosystem should be remodelling the current anthrosphere to a “green anthrosphere”. Designing an industrial ecosystem is actually a business model that requires the following three aspects to be considered properly [87]: 1. Goal modelling: common goals for industrial ecosystem designing are waste reduction, compilation with government rules, increasing industrial efficiencies, etc. 2. Ecosystem modelling: It includes considering different ecosystem elements. 3. Platform modelling: for controlling and monitoring routine operations. Designing an IE requires extensive study to understand its viability and longevity. All aspects including platform coordinators as well as business models should be considered before its implementation. These measures, however, do not guarantee the complete success of an industrial environment, but they do assist in its implementation.

7.6 Policies and paradigm for the GE A GE can help improve the industrial ecosystem as eventually, it is nothing but an integration of three paradigms: IS, CDM and IE. A GE according to the modern concept [89] is an economic model that focuses on minimizing the negative effects of industrial development on the environment and improving human well-being and social equity. The GE aims at creating sustainable, bio-based and bio-beneficial processes capable of giving real and intangible benefits to all people today and in the future, in all parts of the world. The GE is different from the industrial economy as it follows a closed-loop approach and hence, it is also called the circular economy. It follows six basic principles: (1) regenerate, (2) loop, (3) virtualize, (4) share, (5) optimize and (6) exchange [90]. Following these regenerative green approaches, we can gain upgraded and productive industrial ecosystem approaches without overexploitation and pollution of natural resources [91]. The idea of a GE has arisen during the past 10 years as a framework for a policy that aims to reduce poverty and promote long-term growth through the use of environmentally friendly industrial operations. It is projected that by 2030, nearly 25 million people are expected to depend on the GE for their livelihood [92]. This highlights the value of a GE for the production industries, employment growth and the output of the global economy (GDP).

7.7 Conclusions The achievements in social organization in the civilized world and latest in the globalized world have been achieved in a highly efficient and impressive manner.

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7. Green anthrosphere through industrial ecology

Anthropocene is involving the continuous mimicking expansion of developmental pathways of the past century and is not a much valid option for the achievement of a sustainable future. Humanity is the interwined embedded global force in structuring the operation of the biosphere. The loss of biodiversity and climate change is the indicator of the situation. The environmental awareness and growing concern for organizations and individuals about global warming will continue to increase green technology growth. Governmental organizations are starting to invest in the businesses of green technology to decarbonize the economy and develop the countries to make them energy efficient globally. It is the right time when science is needed at its peak. Science can provide informed agreements about the facts and trade-offs of misinformation and polemics. The global challenges that visualize the governance over humanity to mobilize the best to offer for political will and sustainable futures and also competence to implement the decisions that help to sustain humanity and rest living world for our future of millennium. The urgency is needed for societies, people, economics and culture to become highly active and govern nature’s contribution toward well-being and buildings. Conclusively, it is still the right time to maintain the development of the earth by laying the foundation of human active plans within the planetary boundaries for a prosperous future (Figs 7.1 and 7.2).

FIGURE 7.1 Schematic representation regarding approaches for reduction of chemical use in industrial ecology.

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FIGURE 7.2 Advantages of greener anthrosphere through industrial ecology.

References [1] D.T. Rogers, Fundamentals of Environmental Law and Compliance, CRC Press, 2022. [2] D. Dell’Angelo, Computational chemistry and the study and design of catalysts, Green Chemistry and Computational Chemistry, Elsevier, 2022, pp. 299 332. Available from: https://www.sciencedirect.com/science/article/pii/B9780128198797000106. [3] M. Ogle, K. Butterbach-Bahl, L. Cardenas, U. Skiba, C. Scheer, From research to policy, optimizing the design of a national monitoring system to mitigate soil nitrous oxide emissions, Curr. Opin. Environ. Sus. 47 (2020) 28 36. [4] K. Jones, Stanley E. Manahan, Water Chemistry. Green science and technology of nature’s most remarkable resource, Chromatographia 73 (2011) 1039. Available from: https://doi.org/10.1007/s10337-011-1944-3. [5] K.L. McCurley, J.W. Jawitz, Hyphenated hydrology, interdisciplinary evolution of water resource science, Water. Resour. Res. 53 (2017) 2972 2982. [6] R. Wallace, A. Liebman, L. Bergmann, R.G. Wallace, Agribusiness vs. public health, disease control in resource-asymmetric conflict, Essays on Strategy and Public Health, Springer, Cham, 2022, pp. 89 118. [7] S.L. Lewis, M.A. Maslin, Defining the anthropocene, Nature 519 (2015) 171 180. ´ ngel, Y. Saito, I. Overeem, C.J. Vo¨ro¨smarty, H. Wang, et al., Earth’s sediment cycle during the [8] J. Syvitski, J.R. A Anthropocene, Nat. Rev. Earth. Env. 3 (2022) 179 196. [9] P.W. Keys, V. Galaz, M. Dyer, N. Matthews, C. Folke, M. Nystro¨m, et al., Anthropocene risk, Nat. Sustain. 2 (2019) 667 673.

Green Chemistry Approaches to Environmental Sustainability

144

7. Green anthrosphere through industrial ecology

[10] D. Maggs, J. Robinson, Recalibrating the anthropocene, sustainability in an imaginary world, Environ. Philo 13 (2016) 175 194. [11] S. Manahan, Environmental Chemistry, CRC press, Boca Raton, FL, USA, 2017. [12] U. Mining, Basic Concepts, in: Pathal Pankaj, Ranjan Rout Prangya (Eds.), Urban Mining for Waste Management and Resource Recovery, Sustainable Approaches, CRC press, 2021. [13] P. Jo¨ckel, Earth system models, challenges in a changing HPC environment. Available from: https://elib.dlr. de/75712/. [14] S.K. Bhosale, 2015. The Concept of Ecology and Environment. http://dspace.vpmthane.org:8080/jspui/bitstream/123456789/4202/1/FC%20Sem%202%20THE%20CONCEPT%20OF%20ECOLOGY%20AND% 20ENVIRONMENT.pdf. [15] S. Chand, P.R. Rout, P. Pathak, Basic concepts, potentials, and challenges of urban mining, Urban Mining for Waste Management and Resource Recovery, CRC Press, 2021, pp. 1 15. [16] P. Selcer. Anthropocene Encyclopedia of the history of science. University of Michigan, 3, 2021. https://lps. library.cmu.edu/ETHOS/article/id/483/. [17] S.E. Manahan, Industrial Ecology, Environmental Chemistry and Hazardous Waste, CRC press, Routledge, 2017. [18] D. Mulvaney, Fundamentals of energy science, Sustain. Energy Trans. (2020) 33 51. [19] T.A. Costa-Silva, A.K.F. Carvalho, C.R.F. Souza, H.F. De Castro, L. Bachmann, S. Said, et al., Immobilized enzyme-driven value enhancement of lignocellulosic based agricultural byproducts, Application in aroma synthesis, J. Clean. Prod. 284 (2020) 124728. [20] O. Lavrinenko, S. Ignatjeva, A. Ohotina, O. Rybalkin, D. Lazdans, The role of green economy in sustainable development case study, the EU states, Entrepreneurship. Sustain. 6 (2019) 1113. [21] N.J. Smith, G.W. McDonald, M.G. Patterson, Biogeochemical cycling in the anthropocene, quantifying global environment-economy exchanges, Eco.Mode 418 (2020) 108816. [22] C.C. Barton, M.O. Ainerua, Environmental toxicology, hazardous waste, Information Resources in Toxicology, Academic Press, 2020, pp. 321 329. [23] C. Mohan, N. Kumari, J. Robinson, Sustainable and environmental friendly energy materials, Mater. Today: Proc. 69 (2022) 494 498. [24] D.G. Strawn, H.L. Bohn, G.A. O’Connor. Soil Chemistry. Eds, Wiley-Blackwell, Wiley, 376, 2020. [25] P.D. Jensen, L. Basson, M. Leach, Reinterpreting industrial ecology, J. Ind. Ecol. 15 (2011) 680 692. [26] J.G. Speight. Global Climate Change Demystified. Eds, Wiley-Blackwell, Wiley, 2019. [27] Y. Mishenin, I. Koblianska, V. Medvid, Y. Maistrenko, Sustainable regional development policy formation, role of industrial ecology and logistics, Entrepreneurship. Sustain. 6 (2018) 329 341. [28] V. Albino, L. Fraccascia, T. Savino, Industrial symbiosis for a sustainable city, technical, economical and organizational issues, Procedia Eng. 118 (2015) 950 957. [29] A.P. Velenturf, P. Purnell, Principles for a sustainable circular economy, Sust. Prod. Consum. 27 (2021) 1437 1457. [30] Z. Yeo, D. Masi, J.S. Low, Y.T. Ng, P.S. Tan, S. Barnes, Tools for promoting industrial symbiosis, a systematic review, J. Ind. Ecol. 23 (2019) 1087 1108. [31] S.E. Manahan, Environmental Chemistry, 8th ed., CRC press, Boca Raton, FL, USA, 2004. CRC Press/Lewis Publishers. [32] S. Lahane, R. Kant, Investigating the sustainable development goals derived due to adoption of circular economy practices, Waste Manage 143 (2022) 1 14. [33] R. Hackl, E. Andersson, S. Harvey, Targeting for energy efficiency and improved energy collaboration between different companies using total site analysis TSA, Energy 368 (2011) 4609 4615. [34] A. Hein, M. Jankovic, R. Farel, B. Yannou. A data- and knowledge-driven methodology for generating ecoindustrial park architectures. Proceedings of the ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. Volume 4, 21st Design for Manufacturing and the Life Cycle Conference; 10th International Conference on Micro- and Nanosystems, Charlotte, North Carolina, USA. 21 24, 2016. Available from: https://doi.org/10.1115/DETC2016-59171. [35] I.J. Ronoh. Developing an Eco-Industrial Park; Structures and Policies, a Case Study of the KenGen Green Energy Park, Kenya.Doctoral dissertation, School of Science and Engineering Reykjavı´k University, Menntavegur, Reykjavı´k, Iceland, 2020.

Green Chemistry Approaches to Environmental Sustainability

References

145

[36] B. Song, Z. Yeo, P. Kohls, C. Herrmann, Industrial symbiosis, exploring big-data approach for waste stream discovery, Procedia CIRP 61 (2017) 353 358. [37] T. Togawa, T. Fujita, L. Dong, S. Ohnishi, M. Fujii, Integrating GIS databases and ICT applications for the design of energy circulation systems, J. Clean. Prod. 114 (2016) 224 232. [38] P.C. Chen, H.W. Ma, Using an industrial waste account to facilitate national level industrial symbioses by uncovering the waste exchange potential, J. Ind. Ecol. 19 (2015) 950 962. [39] R. Branson, Re-constructing Kalundborg, the reality of bilateral symbiosis and other insights, J. Clean. Prod. 12 (2016) 4344 4352. [40] J. Tian, C. Fang, J. Qiu, J. Wang, Analysis of pollution characteristics and influencing factors of main pollutants in the atmosphere of Shenyang City, Atmosphere 11 (2020) 766. [41] I. Manisalidis, E. Stavropoulou, A. Stavropoulos, E. Bezirtzoglou, Environmental and health impacts of air pollution, a review, Front. Public Health. 8 (2020) 14. [42] G. Liu, Y. Shi, G. Guo, L. Zhao, J. Niu, C. Zhang, Soil pollution characteristics and systemic environmental risk assessment of a large-scale arsenic slag contaminated site, J. Clean. Prod. 251 (2020) 119721. [43] C. Mohan, N. Kumari, Synthesis of Acid Activated and Silicotungstic Acid (STA) Intercalated Montmorillonite Clay as Green Catalyst, Mater. Today: Proc. 56 (2022) 971 975. [44] W. Abdussalam-Mohammed, A. Qasem Ali, O.A. Errayes, Green chemistry, principles, applications, and disadvantages, Chem. Methodol. 4 (2020) 408 423. [45] K. Liu, X. Guan, C. Li, et al., Global perspectives and future research directions for the phytoremediation of heavy metal-contaminated soil, a knowledge mapping analysis from 2001 to 2020, Front. Environ. Sci. Eng. 16 (2022) 73. [46] G.L. Burgess. Effects of Heavy Metals on Benthic Macroinvertebrates in the Cordillera Blanca, Peru. WWU Graduate School Collection, 414, 2015. https://cedar.wwu.edu/wwuet/414/. [47] M. Mokarram, A. Saber, V. Sheykhi, Effects of heavy metal contamination on river water quality due to release of industrial effluents, J. Clean. Prod. 277 (2020) 123380. [48] W.C. Lin, M.A. Li, A. Burns, Drinking water sensor for lead and other heavy metals, Anal. Chem. 89 (17) (2017) 8748 8756. [49] S.E. Manahan, Fundamentals of Environmental Chemistry, CRC press, Boca Raton, FL, USA, 2011. [50] F. Jan, N. Min-Allah, D. Du¨s¸ tego¨r, IoT based smart water quality monitoring: recent techniques, trends and challenges for domestic applications, Water 13 (2021) 1729. [51] N. Stone-Weiss, R.E. Youngman, R. Thorpe, N.J. Smith, E.M. Pierce, A. Goel, An Insight into the Corrosion of Alkali Aluminoborosilicate Glasses in Acidic Environments, 22, RSC, 2020, pp. 1881 1896. [52] M.S. Jellesen, A.A. Rasmussen, L.R. Hilbert, A review of metal release in the food industry, Corros. Mater. 57 (2006) 387 393. [53] P. Tiwari, M. Srivastava, R. Mishra, G. Ji, R. Prakash, Economic use of waste Musa paradisica peels for effective control of mild steel loss in aggressive acid solutions, J. Environ. Chem. Eng. 6 (4) (2018) 4773 4783. [54] V. Hemapriya, I. Chung, S. Kim, M. Prabakaran, Inhibitory effect of biowaste on copper corrosion in 1 M HCl solution, Mater. Today Comm. 27 (2021) 102249. [55] A. Maertens, Green chemistry for green toxicology, Green. Toxicology Mak. Chem. Benign Des. (2022) 1 30. Available from: https://doi.org/10.1039/9781839164392-00001. [56] R.A. Sheldon, Fundamentals of green chemistry: efficiency in reaction design, Chem. Soc. Rev. 41 (4) (2011) 1437 1451. [57] R.K. Sharma, S. Gulati, S. Mehta, Preparation of gold nanoparticles using tea: a green chemistry experiment, J. Chem. Educ. 89 (10) (2012) 1316 1318. [58] C.J. Li, M. Trost, Green chemistry for chemical synthesis, Proc. Natl. Acad. Sci. 105 (36) (2008) 13197 13202. [59] R.A. Sheldon, The E factor 25 years on: the rise of green chemistry and sustainability, Green Chem. 19 (1) (2017) 18 43. [60] P. Anastas, N. Eghbali, Green chemistry, principles and practice, Chem. Soc. Rev. 39 (2010) 301 312. [61] R. Bergman, C H activation, Nature 446 (2008) 391 393. [62] A. Ivankovi´c, A. Dronji´c, A.M. Bevanda, S. Tali´c, Review of 12 principles of green chemistry in practice, Int. J. Sustain. Green Energy 6 (3) (2017) 39 48. [63] M. Zhang, W. Wang, F. Wu, T. Zheng, J. Ashley, M. Mohammadniaei, et al., Biodegradable Poly(γ-glutamic acid) glucose oxidase carbon dot nanoparticles for simultaneous multimodal imaging and synergetic cancer therapy, Biomaterials 252 (2020) 120106.

Green Chemistry Approaches to Environmental Sustainability

146

7. Green anthrosphere through industrial ecology

[64] M. Nendza, S. Gabbert, R. Kuhne, A. Lombardo, A. Roncaglioni, E. Benfenati, et al., A comparative survey of chemistry-driven in silico methods to identify hazardous substances under REACH, Regul. Toxicol. Pharmacol. 66 (3) (2013) 301 314. [65] M. Choudhary, S. Gupta, M.K. Dhar, S. Kaul, Endophytic fungi-mediated biocatalysis and biotransformations paving the way toward green chemistry, Front. Bioeng. Biotech 9 (2021) 419. [66] L. David, B. Moldovan, Green synthesis of biogenic silver nanoparticles for efficient catalytic removal of harmful organic dyes, Nanomaterials 10 (2020) 202. [67] A. Roy, H.C. AnandaMurthy, H.M. Ahmed, M. Nazmul, P. Ram, Phytogenic synthesis of metal/metal oxide nanoparticles for degradation of dyes, J. Renew. Mater. 10 (2022) 1911 1930. [68] C. Ottone, O. Romero, C. Aburto, A. Illanes, L. Wilson, Biocatalysis in the winemaking industry, challenges and opportunities for immobilized enzymes, Compr. Rev. Food. Sci. Food. Saf. 19 (2020) 595 621. [69] A. Cano-Flores, J. Go´mez, I.S. Escalona-Torres, B. Velasco-Bejarano, Microorganisms as biocatalysts and enzyme sources, in: M. Blumenberg, M. Shaaban, A. Elgaml (Eds.), Microorganisms, 2020, pp. 275 306. [70] F.A. Bassyouni, S.M. Abu-Bakr, M.A. Rehim, Evolution of microwave irradiation and its application in green chemistry and biosciences, Res. Chem. Intermed. 38 (2012) 283 322. [71] G. Chatel, J.C. Colmenares, Sonochemistry: from basic principles to innovative applications, Top. Curr. Chem. 375 (2017) 8. [72] M. Oelgemo¨ller, C. Jung, J. Mattay, Green photochemistry: production of fine chemicals with sunlight, Pure Appl. Chem. 79 (11) (2007). [73] K. Masakazu, T. Hayakawa, G.H. Takaoka, T. Miyazaki, Structure and adhesion of hydroxyapatite films electrochemically deposited onto titanium substrates under short-pulse current in metastable calcium, Key Eng. Mater. (2008) 396 398. [74] S.E. Manahan, Environmental Science and Technology, A Sustainable Approach to Green Science and Technology, CRC press, Boca Raton, FL, USA, 2006. [75] K.M. Nampoothiri, N.R. Nair, R.P. John, An overview of the recent developments in polylactide PLA research, Bioresour. Technol. 101 (2010) 8493 8501. [76] S. Sharma, J. Das, W.M. Braje, A.K. Dash, S. Handa, A glimpse into green chemistry practices in the pharmaceutical industry, Chem. Sus. Chem. 13 (2020) 2859. [77] S. Jin, F. Byrne, C.R. McElroy, J. Sherwood, H.J. Clark, A.J. Hunt, Challenges in the development of biobased solvents, a case study on methyl 2,2-dimethyl-1,3-dioxolan-4-yl methyl carbonate as an alternative aprotic solvent, Faraday Discuss. 202 (2017) 157 173. [78] C.J. Clarke, W.C. Tu, O. Levers, A. Bro¨hl, J.P. Hallett, Green and sustainable solvents in chemical processes, Chem Rev. 118 (2018) 747 780. Available from: https://doi.org/10.1021/acs.chemrev.7b00571. [79] M. Mondal, U. Bora, Eco-friendly Suzuki Miyaura coupling of arylboronic acids to aromatic ketones catalyzed by the oxime-palladacycle in biosolvent 2-MeTHF, New. J. Chem. 40 (2016) 3119 3123. [80] N. Chakraborty, A. Banerjee, R. Pal, Biomonitoring of lead, cadmium and chromium in environmental water from Kolkata, North and South 24-Parganas using algae as bioreagent, J. Algal Biomass Utln 2 (2011) 27 41. [81] I. Patra¸scu, C.S. Bıˆldea, A.A. Kiss, Novel eco-efficient process for dimethyl carbonate production by indirect alcoholysis of urea, Chem. Eng. Res. Des. 160 (2020) 486 498. [82] J. Liu, R. Liu, Y. Wei, M. Shi, Recent developments in cyclopropane cycloaddition reactions, Trends Chem. 1 (2019) 779 793. [83] D.J. Garole, R. Hossain, V.J. Garole, V. Sahajwalla, J. Nerkar, D.P. Dubal, Recycle, recover and repurpose strategy of spent Li-ion batteries and catalysts, current status and future opportunities, Chem. Sus. Chem 13 (2020) 3079. [84] G. Bhattacharya, S.J. Fishlock, J.A. McLaughlin, S.S. Roy, Metal-oxide nanomaterials recycled from E-waste and metal industries, a concise review of applications in energy storage, catalysis, and sensing, Int. J. Energy. Res. 45 (2021) 8091 8102. Available from: https://doi.org/10.1002/er.6336. [85] R. Farzana, K. Hassan, V. Sahajwalla, Manganese oxide synthesized from spent Zn-C battery for supercapacitor electrode application, Sci. Rep. 9 (2019) 8982. [86] M.C. Vyas, J. Pitroda, Fly ash and recycled coarse aggregate in concrete, new era for construction industries a literature review, Int. J. Eng. Trends. Appl. 4 (2013) 1782 1787. [87] M. Benedict, L. Kosmol, W. Esswein, Designing industrial symbiosis platforms from platform ecosystems to industrial ecosystems, PACIS Proc. 306 (2018). https://aisel.aisnet.org/pacis2018/306.

Green Chemistry Approaches to Environmental Sustainability

References

147

[88] M. Chertow, J. Ehrenfeld, Organizing self-organizing systems, J. Ind. Ecol. 16 (2012) 13 27. [89] D. D’Amato, N. Droste, B. Allen, M. Kettunen, K. La¨htinen, J. Korhonen, et al., Green, circular, bio economy, a comparative analysis of sustainability avenues, J. Clean. Prod. 168 (2017) 716 734. [90] M. Lewandowski, Designing the business models for circular economy—towards the conceptual framework, Sustainability 8 (2016) 43. [91] P. Ghisellini, C. Cialani, S. Ulgiati, A review on circular economy, the expected transition to a balanced interplay of environmental and economic systems, J. Clean. Prod. 114 (2016) 11 32. [92] K. Shulla, B.F. Voigt, S. Cibian, G. Scandone, E. Martinez, F. Nelkovski, et al., Effects of COVID-19 on the sustainable development goals SDGs, Discover. Sus. 2 (2021) 1 19.

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C H A P T E R

8 Plant-derived compounds and their green synthesis in pharmaceuticals and nutraceuticals Babita1, Vandana Singh2 and Chandra Mohan3 1

Department of Pharmacology, School of Allied Health Sciences, Sharda University, Gr. Noida, Uttar Pradesh, India 2Department of Microbiology, School of Allied Health Sciences, Sharda University, Gr. Noida, Uttar Pradesh, India 3Department of Chemistry, School of Basic and Applied Sciences, K. R. Mangalam University, Gurugram, Haryana, India

8.1 Introduction Nanotechnology is an advanced technology in the various fields of science that is widely used in many areas including pharmaceutical and nutraceuticals. Nanotechnology is being used in drug synthesis and drug delivery particularly [1]. Medical science can be upraised by the production and application of nanotechnology in various fields which can give solutions to several severe diseases by providing treatment and diagnosis [2]. Nanotechnology is an advanced multidisciplinary field and integrates with several branches of sciences like engineering, chemistry, physics, and biotechnology as well as material science [3]. Nanoparticles (NPs) are synthesized in various shapes, size and dimensions of about 1 100 nm with different chemical compounds that can be used in pharmaceutical industries in drug manufacturing and biomedical applications for several purposes [4]. NP is a single unit to carry drugs, and it is designed to transport drugs to targeted sites. Currently, the interest towards the application of metal NPs or nanometre dimension has increased because of various properties that make it appropriate for use in medical science [5]. The surface-to-mass ratio of NPs is much larger that makes it one of the unique properties of NPs, and its larger surface area increases its ability to adsorb, attach, and carry other molecules of drugs and proteins. However, chemically synthesized NPs can be toxic in the usage to environment as well as for organisms, which result in limitation in usage of synthetic NPs [6].

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The application of nanotechnology in pharmacotherapy may offer some exciting possibilities such as one use of NPs is being widely developed for designing NPs in drug delivery to target sites of disease. Particles are designed to work on specific sites to avoid toxicity for other parts of the body and to enhance direct treatment. This technique shows beneficial effects by reducing damage to healthy cells in the body and allows early healing of diseases [7]. Researchers and scientists are working on the development of nanovesicles to deliver stem cells to damaged heart tissue. They fused cardiac stem cells to platelet nanovesicle that move towards injury after administration in patients which possess the repairing capability of parental cell types [4]. Another study was conducted in John Hopkins University to manufacture a sensor for detecting COVID-19 and other viruses [8]. Early detection of many cancers before it metastasizes is very important for early treatment, but it is generally diagnosed at advanced stages. Liquid biopsy was used to attach antibodies with nanotubes of carbon in chips that make it feasible to detect cancer cells in blood circulation in early stages [9]. Continuous research studies are required to find out more effective NPs which may carry drugs for different target sites. Scientists mentioned that two types of NPs are used in research to deliver drugs to tumours, first type target tumour cells and second one act on signal generated by first NPs [10]. One research group has found that disc-shaped NPs will attach to tumour for longer time as compared to spherical-shaped NPs that provide a well efficient transfer of therapeutic drugs [11]. Other research groups have found that rod-shaped NPs are more efficient in chemotherapy drug delivery to cancer cells of breast [12]. The potential use of nanotechnologies for nanomedicines synthesis in medical science can enhance better treatment options for cancer, diabetes, chronic pulmonary disease, and viral and fungal infections. With the introduction of nanopharmacology, the development of new medicines will be easier and worthwhile to the drug delivery system in several untreated diseases. Thus nanopharmacology is being anticipated as the foremost treatment for disease-like cancer and HIV, specifically untreatable diseases [13]. Nanomaterials have been discovered as favourable tools for the development of drugs. Several properties of NPs are applied in designing of therapeutic medicines and these properties are chemical composition of nanomaterials, shape design, size, charge on surface and its solubility. The nanomaterials properties can affect the interaction of nanostructures with biomolecules of cells [6]. Further, more research is needed to synthesize safe and effective nanocarrier/nanosensors for treatment as well as diagnosis of severe diseases. Metal NPs have been investigated widely in the past few years such as Cu (copper), Ag (silver), Au (gold) and Zn (zinc) NPs; these NPs are being tested for drug delivery in cancer and other diseases as a therapeutic solution; it has been found that NPs reduce side effects of drugs on required dosage [14]. The size of some biomolecules is similar to most of metal NPs, that is, proteins size lies between 1 2 nm, cell membrane 6 20 nm, haemoglobin 5 nm and DNA 2 nm in diameter whereas size of NPs is equal to 50 nm or less; NPs can interact with biomolecules of human cells [15]. The NPs equal to or less than 20 nm in size can circulate throughout the body and various target organs in the body including the brain by crossing blood brain barrier which is associated with possible damage in the cells at cellular and molecular level [16]. NPs can enter the brain through nasal olfactory pathway, which is the best method to bypass the blood-brain barrier to enter the brain. Nanomaterials may alter neuronal function and produce reactive oxygen species (ROS), leading to neuronal apoptosis. The NPs clearance rate is slower,

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accumulation may induce inflammation, alter function of the nervous system and finally may accelerate neurodegeneration [17]. The toxicity of NPs is not only associated to size, surface area, coating, dissolution, and shape, but synthetic chemical structure and capping agents are also responsible for it. Moreover, it has been reported that NPs may cause oxidative stress, genetic material destruction, breakage of DNA strand and mutation [6]. NPs attached with DNA directly may cause primary toxicity, whereas secondary genotoxicity may occur due to ROS/RNS species that are produced by NPs. NPs can accelerate the ROS synthesis by inducing inflammatory cells such as neutrophils [18]. Zinc oxide (ZnO) NPs are used mostly in pharmaceutical and cosmetic products for various purposes [19]. Nevertheless, some studies mentioned that ZnONPs can trigger oxidative stress which may lead to DNA damage, replication disorder in different phases of cell cycle and finally mitochondrial-mediated apoptosis [20,21]. Genotoxicity related to NPs mainly occurs due to synthesis of ROS and RNS at high level; these high amounts of oxidative stress may cause damage to genetic materials [22]. Nonmetallic NPs can trigger oxidative stress, that is, NPs made up of silica and ceramic show harmful effects at cellular level. Cytotoxic effects were observed in all vital organs, including lungs, liver, heart and even in the brain due to oxidative stress induced by ceramic NPs which is used in drug delivery, it also shows carcinogenic and teratogenic effects [23]. Similarly, silica-based NPs were found to initiate oxidative stress and NO/NOS species imbalance, resulting in inflammation [24]. Neurotoxicity can be reversible or irreversible in terms of toxicity and manipulate neuron structure and function in nervous systems. Researchers have been working to provide a smart drug delivery system for the brain, but there is no sufficient data available on neurotoxicity of NPs. The systemic toxicity has been reported in studies such as the dermal changes, sensitization, cardiac toxicity, neurotoxicity and growth toxicity due to NPs’ complete structure or its decomposition products. There is no clinical trial data available yet on toxicity of NPs that need to be addressed before working towards nanoformulation. The applications of nanomaterial compounds are clearly accepted worldwide due to promising and emerging technology. However, the toxicity of nanomaterials requires some attention to overcome its toxic effects in upcoming drug formulations. The use of synthetic and harmful chemicals for synthesis of nanostructure should be stopped, instead of this practice green synthesis should be introduced by use of several available plant sources like fungi, algae and bacteria. Green syntheses of NPs using plant extracts should promote more due to safety and nonuse of hazardous chemicals. Plant-derived NPs are nontoxic, eco-friendly, safe, easy to use and cost-effective. Plant-based NPs can be synthesized by green synthesis that can prevent and heal high-risk disease. These NPs are also utilized in food technology, cosmetics, agriculture and advance application in pharmaceuticals along with the nutraceutical field [3]. The synthesis of metallic NPs with use of biological compounds can be an eco-friendly approach to get significant attention. As per traditional knowledge on medicinal plants, some phytochemicals that have properties to cure various types of diseases and their uses in pharmaceutical industries are being raised [25]. These plant-derived phytochemicals included primary metabolites, secondary metabolites, plants products and fibres work as natural substrates, cofactors, inhibitors of enzymatic reactions, absorbents, legends, scavengers, etc. Research is supporting the beneficial effects of plant derived compounds for human health [26]. Phytochemical constituents can be converted into NPs by using nanotechnology to increase their effects on human health

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and diseases. Biodegradable nanopolymers including polyglycolic acid, poly (lactic-co-glycolic acid) and polylactide are completely dissolved. Thus it can be used in synthesis of nanocarriers that are being used in packaging of anticancer drugs to reduce toxicity [27]. These types of biodegradable biosynthesis of nanostructure are an important compound for pharmaceutical and nutraceutical application as these options provide us nontoxic, cheap, eco-friendly and effective treatment. Plants are associated with many ranges of metabolites and phytochemicals that may be utilized as stabilizing and reducing agents in green synthesis of NPs as per the requirement of application. The plant-derived pharmacologically active biomolecules can show significant therapeutics effects if used against human pathogens such as antibacterial activity.

8.2 Plant-derived nanoparticles in pharmaceuticals 8.2.1 Therapeutic applications Nanoformulation of drugs can enhance bioavailability of drugs to a greater extent. Thus therapeutic application of nanoformulation can replace many standard drugs from the market due to poor bioavailability [28]. Additionally, this treatment option may improvise pharmacokinetics of drug formulation by smooth degradation of peptides and proteins in the body. Current studies mentioned that exosome-like NPs of grape were given via oral route to mice; this treatment induces intestinal stem cells proliferation in the epithelium of the intestine. The combined knowledge of nanotechnology and phytochemicals is utilized for production of therapeutic drugs to synthesis nanocarrier or nanomedicines of green synthesis by using resources of plants [3]. The plants metabolites have shown great antimicrobial and antioxidant activities, and many plants are being used to produce medicinal NPs such as protein-based NPs, carbon-based and polysaccharide-based, adhesive, exosome-like, lipid-based and silica NPs. In addition to being safer drugs, plant-derived NPs introduce novel drug delivery options that can reduce toxicity of drugs and it can enhance significant use of plant-derived NPs in the pharmaceutical industries [29]. Various types of NPs are developed from plants based on pharmacology of compounds for therapeutic application as shown in Table 8.1.

8.3 Antibacterial activity Bacterial infection can cause mortality in multi drug-resistant patients that is still a major concern of medical field, and nanotechnology can be a new solution. Green synthesis NP complexation will be a more suitable option of treatment that may prevent biofilm formation and bacterial growth by ligand-based complexation with receptors like lipid, protein, phospholipid and lipoteichoic acid at pathogen surface. Thus treatment will be more powerful to restrict the growth of antibiotic resistant bacteria [53]. Currently, research is being conducted on biologically synthesized silver NPs which has shown effective antibacterial activity against several types of bacteria (B. subtilis, K. pneumoniae sp., E. coli and S. aureus) as compared to chemically synthesized drugs [54].

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8.3 Antibacterial activity

TABLE 8.1 Medicinal applications of plant-based nanoparticles. Plant sources

Synthesis NP types

Application

Reference

Moringa oleifera

Polyvinyl alcohol-silver nanoparticles (PVAAgNPs)

Drug-loaded PVA-AgNP arrest cervical cancer cell line (HeLa) proliferation and production an antineoplastic, (inhibit mainly DNA synthesis)

Paul et al. [30]

M. oleifera Lam.

Tungsten nanoparticles (W-NPs)

Antifungal and antibacterial activity against Fusarium exosporium and Bacillus subtilis, another property of cytotoxicity against cancer cell line of breast (MCF-7) and fibroblast cell line (3T3)

Sharma et al. [31]

Cyperus rotundus Gold nanoparticles (CR) (AuNPs)

Antibacterial activity against various Grampositive, Staphylococcus aureus, B. subtilis and Gram-negative, Salmonella paratyphi, Escherichia coli, bacterial species

Sasidharan and Pottail [32]

Morus alba (White mulberry)

AuNPs

Antibacterial, that is, Vibrio cholera and S. aureus

Adavallan and Krishnakumar [33]

Phyllanthus niruri

AgNPs

Mosquitocidal properties, against the dengue vector, Aedes aegypti species

Suresh et al. [34]

Abelmoschus moschatus

AgNPs

Antimicrobial activity (Pseudomonas aeruginosa, S. aureus, and B. subtilis)

Rane et al. [35]

Rhizophora apiculata

AgNPs

Synthesized NPs showed effective results in bone Wen et al. [36] cancer cell lines, osteosarcoma cells (MG-63) in vitro

Catharanthus roseus Linn. G.

AgNPs

Antiplasmodial activity against Plasmodium falciparum

Murugan et al. [37]

Atropa acuminata AgNPs (Indian Belladonna)

Anti-inflammatory role by controlling Rajput et al. [38] autoantigen production, cytotoxic effect work against the cervical cancer cell line, HeLa. AgNPs of belladonna shows the potential halting of Bovine Serum Albumin (BSA) protein denaturation

Atropa acuminata AgNPs

Anti-inflammatory role

Elangovan et al. [39]

Passiflora caerulea L. (Passifloraceae)

Zinc oxide Antibacterial activity against infectious disease nanoparticles (ZnONPs)

Aloe vera

AgNPs

Antibacterial activity against Kocuriavarians, epidermidis (G1) and P. aeruginosa (G2)

Tippayawat et al. [41] Campillo et al. [42]

Pelargonium graveolens

AgNPs

Antifungal activity

Nancy and Elumalai [43]

P. graveolens

AgNPs

Wound healing property and antifungal effect Bere et al. [44] against Aspergillus flavus, Candida albicans, Candida tropicalis, Aspergillus niger

Santhoshkumar et al. [40]

(Continued)

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TABLE 8.1 (Continued) Plant sources

Synthesis NP types

Application

Reference 1

Emblica Phytofabricated officinalis (Amla) selenium nanoparticles (PF-SeNPs)

Antibacterial activity for G bacteria (S. aureus MTCC 96, Enterococcus faecalis MTCC439, and L. monocytogenes MTCC657)

Gunti et al. [45]

Helianthus annuus (Sunflower) seed

Zirconium oxide nanoparticles (ZrO2NPs)

Inhibit Gram-negative bacteria growth, that is, Klebsiella pneumonia, E. coli, and P. aeruginosa

Goyal et al. [46]

Papaver somniferum L.

Iron oxide (Fe2O3) and lead oxide (PbO) nanoparticles

Antibacterial activity towards pathogenic strains Muhammad et al. such as G2 (K. pneumonia and P. aeruginosa) and [47] G1 (B. subtilis and S. epidermidis) bacterial species. Antifungal against A. flavus, Fusarium solani, Mucor mycosis, A. niger, and A. fumigates. Both NPs show highest antifungal towards F. solani. Cytotoxicity screening performed against human liver cancer, HepG2. PbO NPs show more cytotoxicity as compared to Fe2O3NPs

Basella alba L.

Metallic AgNPs

Antibacterial properties against Gram-positive bacteria, that is, S. aureus, P. aeruginosa and Gram-negative bacteria, that is, Enterococcus, E. coli

Mani et al. [48]

Jatropha curcas (JC)

AgNPs

JC-Ag NPs show action against Listeria monocytogenes, bacterial pathogen (food born)

Chauhan et al. [49]

Carica papaya

AgNPs

Antiviral activity, highly inhibit DENV-2 replication (viral inhibition percentage . 90)

Bere et al. [44]

Mangifera indica

AuNPs

At low dose, antibacterial against E. coli and S. aureus bacterial

Vimalraj et al. [50]

Passiflora caerulea L. (Passifloraceae)

ZnONPs

Antibacterial activity against K. pneumonia, Santhoshkumar Streptococcus sp., Serratia sp., E. coli, and B. subtilis et al. [40] (urinary tract infection)

Momordica charantia

Copper oxide nanoparticles (CuONPs)

It works against multidrug resistance bacteria Streptococcus mutans, B. cereus, S. viridans, Proteus vulgaris, E. coli, and P. aeruginosa

Qamar et al. [51]

Zanthoxylum armatum DC

CuONPs

Antibacterial activity

Bhavyasree and Xavier [52]

8.4 Anti-inflammatory activity Anti-inflammatory properties of natural and nontoxic plant-derived compounds are composed into NPs to target various inflammatory diseases including intestinal bowel disease (IBD) [28]. It has been shown that formulated NPs inhibit molecules of cell cycle regulation such as cyclin D1. NPs are used in leucocytes to find out the exact role in inflammation of the gut. Drug encapsulation in NPs shows better efficacy at a very lower

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concentration of drug as compared to the same drug administered in the form of tablets, capsules and other forms. Plant-derived NPs were used in treatment of IBD by drug delivery methods to target inflamed tissues and pathophysiology of disease [55].

8.5 Anticancer role Plant-derived nanomedicine shows promising anticancer agents because of the easy drug carrier property to target the site of tumour and deliver a number of molecules of drugs at same time. Studies have described that NPs of TiO2 can arrest DNA checkpoints during cell division, and this nanoformulation inhibits cell proliferation [54]. Chemotherapeutic drugs can be synthesized using Zn-TiO2-NPs, Ag-TiO2-NPs and AuTiO2-NPs nanomedicines to treat cancer, and these molecules work as genotoxic agents. Anti-cancerous properties have been found in AuNPs against various cell lines such as A549, MDA-MB, HELLA and K-562 cell lines but the same was not effective against cell lines of Vero [56]. Another study suggests that NPs like ZnO cause apoptosis in cells by inducing ROS production through releasing zinc ions in cells to cause cytotoxicity in cancer cells [57]. The radioactive probes have the ability to penetrate deep into tissues; this property can be used to treat cancer more effectively [58].

8.6 Antiviral role against COVID-19 The recent outbreak of COVID-19 characterized by pneumonia leads to respiratory failure, and in the severe condition it may cause multiorgan failure and death. The current situation of COVID-19 is that there is a requirement of drug development against this deadly virus that is attached to the host cell [59]. Phytochemicals are natural products of plants such as polyphenol, alkaloids, steroids, tannins, flavonoid and coenzymes. These secondary metabolites can be a novel therapeutics option against microorganisms (virus, fungi, bacteria, yeast) [60]. A study has shown that plant-derived vaccine of virus-like particles (VLPs) against COVID-19 works well, and it has been observed that these VLPs mimic the native structure of the virus and are easily recognized by immune cells to develop memory cells against the virus [61]. A study reported that a mask prepared against viral infection containing plant-derived silica NPs that produce ROS in a photocatalysis process may work against pathogens to reduce the SARS-Cov-2 infection [62].

8.7 Plant-derived nanostructures in nutraceuticals formulation Nutraceutical is a term derived from nutrition and pharmaceutics, which reflects its use as a nutrition in the form of medicines. These products have potential of treatment and need to be treated as similar as pharmaceuticals. Nutraceuticals products are other than nutrition and used as medicines, derived from the natural sources like plants, bacteria, fungi and virus to aid health benefits. Hence, it is defined as the substance or food part that provides us medicinal bioactive phytochemicals to maintain health. Nutraceuticals are

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divided into three different groups such as herbals, nutrients (vitamins and minerals) and dietary developments [63]. Nutraceutical products are a daily requirement in the form of medicines to improve health status, delay ageing, maintain physiology and as a prophylactic drug [64]. Plant-based nutraceuticals have strong recommendations in using nutraceutical to improve health, prevent and treat disease. Nutraceuticals serve as therapeutics on patients of specific disease, prescribed as food supplements for the general population [65]. The economical production and availability of nutraceuticals is a highly desirable objective to improve the health of the people by prophylactic in nature of nutraceutical products despite other drugs which are only used in diseases [66]. Nutraceuticals active compounds are present in nature in abundance and show therapeutic effects in achieving health benefits. However, the use of nutraceuticals products has many health benefits, though there is limitation of water insolubility and instability in respect to environmental conditions but when encapsulate in nanostructure it shows synergistic effect of nutraceuticals with material of nanostructure which increase its bioavailability. Thus it gives confirmation for application in the field of food [67]. Other challenges with nutraceuticals are that these products show poor water solubility and stability, and also susceptibility for oxygen, light with poor absorption and chemical modulation. Hence, nanotechnology could be a new approach in nutraceuticals for therapeutic purposes. The encapsulation of natural compounds by applying nanotechnology can enhance the efficacy of nutraceutical agents for various purposes like disease prevention and treatment, which can be a very promising method in nutraceuticals drug delivery to overcome the limitations of previously available drug formulation [68]. The nanoencapsulation methods can provide maximum possible protection to nutraceutical chemicals from environmental factors such as light, temperature, oxygen and pH, whereas it can increase solubility, bioavailability of substances and target site delivery with controlled release encapsulated chemical [69 71]. The various materials are being tested for drug delivery as nanostructure such as lipid, polymeric, protein but compositions should select on the basis of compound to be encapsulated to deliver on target site [72,73]. Thus nutraceutical’s nanoencapsulation may enhance the benefits on humans by reducing limitations and side effects. Several forms of nanostructure have been used in encapsulation of nutraceuticals. The polyphenol NPs show antioxidant and anti-inflammatory properties when hydrophobic curcumin encapsulated with soy β-conglycinin [74]. Citrus fruits contain hesperidin and naringin flavonoids that are extracted to encapsulate in AgNPs and AuNPs against pathogen amoebae, that is, Acanthamoeba castellanii and Naegleria fowleri which eat the brain. Hesperidin-loaded AgNPs cause complete mortality of pathogens, which shows strong antimicrobial activity due to silver combination in formulation of drug [75]. The encapsulation of polyphenolic compound resveratrol into cyclodextrin increases its water solubility and consequently, enhances anticancer properties of resveratrol on various cell lines. Researchers reported that resveratrol as a nutraceutical in the form of NPs showed anticancer effect against MCF-7 cell lines, and it also works as an antioxidant and antiinflammatory agent [64,76]. Nanocarriers and nanostructures that are made up of lipidbased compounds are being used in nutraceuticals as well as food industries [77,78]. Solid lipid-based NPs and nanostructure proved to be desirable carriers for resveratrol in oral dosage [79]. Lipid-based vesicles, liposomes, are used for hydrophobic and hydrophilic drug carriers [80]. Vitamin A metabolite, all transretinoic acid, was studied as

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nutraceutical for its anticancer property, when this compound encapsulated in the liposome, which protects it from photodegradation phenomena that can maintain its pharmacological properties. Hence, this liposomal formulation works very promising if applied in pharmaceuticals and nutraceutical industries [81]. Liposomal vesicles are widely being used for carrying phytochemicals compounds like flavonoids due to its antidiabetic, antioxidant and anti-inflammatory properties [82,83]. The flavonoid encapsulation in liposomes can protect it from degradation phenomena [84,85]. Similarly, as mentioned in the above studies, encapsulated in liposomes maintain phytochemical properties by reducing the exposure to environmental conditions [86]. Green tea polyphenols were extracted from leaves that showed several health benefits such as antioxidants, free radical scavenging, anti-inflammatory properties, and lowering bad cholesterol of the body [87]. Nanogel is another nanostructure that is made up of carboxymethyl cellulose and lysozyme with biodegradable a biocompatible drug formulation to carry polyphenol of tea; the encapsulation in nanogel may enhance its stability. Recently, a study has mentioned that nanoformulation of curcumin loaded nanogel ameliorates its anticancer activity on cancer cell lines of hepatoblastoma in humans. Curcumin loaded nanogel also has shown promising results on breast and gastric cancer in humans [88]. Overall results revealed that nanoformulation of drugs showed remarkable and stronger activity of nutraceuticals in comparison to free.

8.8 Conclusion Nanotechnology is one of the modern technologies of science with various applications in major industries such as food and medicine industries. Although NPs have a number of beneficial applications in medical science, many damaging and harmful effects are also associated with NPs. Size of NPs is similar to most biomolecules of cells which can cause alternation in cell functioning. NPs can easily cross all natural barriers of cells including blood-brain barrier [15,16]. Nanomaterials may alter neuronal function and produce ROS that leads to neuronal apoptosis. The NPs clearance rate is slower, accumulation may induce inflammation, altered function of the nervous system and finally may accelerate neurodegeneration [17]. The toxicity of NPs is not only associated size, surface area, coating, dissolution and shape, but synthetic chemical structure and capping agents are also responsible for it. Moreover, it has been reported that NPs may cause oxidative stress, genetic material destruction, breakage of DNA strand and mutation [6]. NPs attached with DNA directly may cause primary toxicity, whereas secondary genotoxicity may occur due to ROS/RNS species that are produced by NPs. NPs can accelerate the ROS synthesis by inducing inflammatory cells such as neutrophils. Nanotoxicology has emerged as a new branch of science to highlight the toxicity of nanomaterials and risk factors for human and environment. Designing of NPs is more important factor, and it should be done meticulously by considering all the factors to minimize toxicity of NPs. In this review, we have discussed some biological NPs and their several applications for pharmaceutical industry; green synthesis of NPs can be a new approach to synthesize biological NPs to formulate drugs from plant sources. Plant-derived NPs are nontoxic, ecofriendly, safe, easy to use, nonuse of hazardous chemicals and cost-effective. The traditional knowledge of plant compounds has shown great medicinal properties, and many plants are being used to produce

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drugs to show medicinal effects against several diseases. Therefore the combination of traditional knowledge of plants with modern nanotechnology may take medical sciences to the next level to fight against many challenging untreatable diseases, which may give better treatment and diagnosis options for patients in the form of target drug delivery. Moreover, nanoformulation of drugs option may improvise pharmacokinetics of drug and enhance bioavailability of drugs to a greater extent. Therapeutic perspective of plant-based NPs can prevent and heal high-risk disease and provide solution to several severe diseases. Thus green synthesis of nanocarriers is being used in packaging of anticancer drugs to reduce systemic toxicity [27]. These types of biodegradable biosynthesis of nanostructure are an important compound for pharmaceutical industries. Plant-based nutraceuticals have strong recommendations in using nutraceutical to improve health, and prevent and treat disease. Nutraceuticals serve as therapeutics on patients of specific disease, prescribed as food supplements for the general population. Hence, nanotechnology could be a new approach in nutraceuticals for therapeutic purposes. The encapsulation of natural compounds by applying nanotechnology can enhance the efficacy of nutraceutical agents for various purposes like disease prevention and treatment. Thus nutraceutical’s nanoencapsulation may enhance the benefits on humans by reducing limitations and side effects of available drugs in the market. Collectively, nanoformulation of nutraceuticals and pharmaceutical agents can be an ideal and promising option of drug delivery in various health issues and challenging diseases in the future. Nevertheless, further studies are required to establish mechanisms of action and toxicity.

References [1] X. Chen, J. Gole, A. Gore, Q. He, M. Lu, J. Min, et al., Non-invasive early detection of cancer four years before conventional diagnosis using a blood test, Nat. Commun. 11 (1) (2020) 1 10. Available from: https://doi.org/ 10.1038/s41467-020-17316-z. [2] N. Jain, P. Jain, D. Rajput, U.K. Patil, Green synthesized plant-based silver nanoparticles: therapeutic prospective for anticancer and antiviral activity, Micro Nano Syst. Lett. 9 (1) (2021). Available from: https://doi.org/ 10.1186/s40486-021-00131-6. [3] C. Hano, B.H. Abbasi, Plant-based green synthesis of nanoparticles: Production, characterization and applications, Biomolecules 12 (1) (2022) 1 9. Available from: https://doi.org/10.3390/biom12010031. [4] S. Attarilar, J. Yang, M. Ebrahimi, Q. Wang, J. Liu, Y. Tang, et al., The Toxicity phenomenon and the related occurrence in metal and metal oxide nanoparticles: a brief review from the biomedical perspective, Front. Bioeng. Biotechnol. 8 (2020)July. Available from: https://doi.org/10.3389/fbioe.2020.00822. [5] P. Sarvarian, P. Samadi, E. Gholipour, K. Shams Asenjan, M. Hojjat-Farsangi, R. Motavalli, et al., Application of emerging plant-derived nanoparticles as a novel approach for nano-drug delivery systems, Immunol. Investig. 51 (4) (2022) 1039 1059. Available from: https://doi.org/10.1080/08820139.2021.1891094. [6] C. Egbuna, V.K. Parmar, J. Jeevanandam, S.M. Ezzat, K.C. Patrick-Iwuanyanwu, C.O. Adetunji, et al., Toxicity of nanoparticles in biomedical application: nanotoxicology, J. Toxicol. 2021 (2021). Available from: https:// doi.org/10.1155/2021/9954443. [7] S. Jain, M.S. Mehata, Medicinal plant leaf extract and pure flavonoid mediated green synthesis of silver nanoparticles and their enhanced antibacterial property, Sci. Rep. 7 (1) (2017) 1 13. Available from: https://doi. org/10.1038/s41598-017-15724-8. [8] D. Paria, K.S. Kwok, P. Raj, P. Zheng, D.H. Gracias, I. Barman, Label-free spectroscopic SARS-CoV-2 detection on versatile nanoimprinted substrates, Nano Lett. (2021). Available from: https://doi.org/10.1021/acs. nanolett.1c04722.

Green Chemistry Approaches to Environmental Sustainability

References

159

[9] M.S. Loeian, S. Mehdi Aghaei, F. Farhadi, V. Rai, H.W. Yang, M.D. Johnson, et al., Liquid biopsy using the nanotube-CTC-chip: Capture of invasive CTCs with high purity using preferential adherence in breast cancer patients, Lab. Chip 19 (11) (2019) 1899 1915. Available from: https://doi.org/10.1039/c9lc00274j. [10] Y. Yao, Y. Zhou, L. Liu, Y. Xu, Q. Chen, Y. Wang, et al., Nanoparticle-based drug delivery in cancer therapy and its role in overcoming drug resistance, Front. Mol. Biosci. 7 (2020) 1 14August. Available from: https:// doi.org/10.3389/fmolb.2020.00193. [11] R. Misra, S. Acharya, S.K. Sahoo, Cancer nanotechnology: application of nanotechnology in cancer therapy, Drug. Discovery Today 15 (19 20) (2010) 842 850. Available from: https://doi.org/10.1016/j.drudis.2010.08.006. [12] X. Wang, Z. Teng, H. Wang, C. Wang, Y. Liu, Y. Tang, et al., Increasing the cytotoxicity of doxorubicin in breast cancer MCF-7 cells with multidrug resistance using a mesoporous silica nanoparticle drug delivery system, Int. J. Clin. Exp. Pathol. 7 (4) (2014) 1337 1347. [13] M. Sikkander, A. Razak, Review on nanotechnology persecute vital role of curative applications in medicinal field and its ailing effects, J. Chem. Technol. Appl. 4 (1) (2021). [14] D. Zhang, X.L. Ma, Y. Gu, H. Huang, G.W. Zhang, Green synthesis of metallic nanoparticles and their potential applications to treat cancer, Front. Chem. 8 (2020) 1 18October. Available from: https://doi.org/ 10.3389/fchem.2020.00799. [15] A. Manuscript, NIH Public Access 62 (3) (2011) 346 361. Available from: https://doi.org/10.1016/j. addr.2009.11.007.Fabrication. [16] P.H.M. Hoet, I. Bru¨ske-hohlfeld, O.V. Salata, Nanoparticles known and unknown health risks, J. Nanobiotechnol. 15 (2004) 1 15. Available from: https://doi.org/10.1186/1477-3155-2-12. [17] H. Fujimaki Nanoparticles and Neurotoxicity. 6267 6280, 2011. https://doi.org/10.3390/ijms12096267. [18] A. Manke, L. Wang, Y. Rojanasakul, Mechanisms of nanoparticle-induced oxidative stress and toxicity, Biomed. Res. Int. 2013 (2013). [19] A. Kołodziejczak-radzimska, & T. Jesionowski Zinc Oxide—From Synthesis to Application: A Review. 2833 2881, 2014. https://doi.org/10.3390/ma7042833. [20] J. Hou, H. Liu, S. Zhang, X. Liu, T. Hayat, A. Alsaedi, et al., Chemosphere mechanism of toxic effects of Nano-ZnO on cell cycle of zebra fi sh (Danio rerio), Chemosphere 229 (2019) 206 213. Available from: https://doi.org/10.1016/j.chemosphere.2019.04.217. [21] V. Sharma, D. Anderson, & A. Dhawan. Zinc Oxide Nanoparticles Induce Oxidative DNA Damage and ROSTriggered Mitochondria Mediated Apoptosis in Human Liver Cells (HepG2). 852 870, 2012. https://doi.org/ 10.1007/s10495-012-0705-6. [22] K. Mortezaee, M. Najafi, H. Samadian, H. Barabadi, A. Azarnezhad, A. Ahmadi, Chemico-biological interactions redox interactions and genotoxicity of metal-based nanoparticles: a comprehensive review, ChemicoBiological Interact. 312 (2019) 108814September. Available from: https://doi.org/10.1016/j.cbi.2019.108814. [23] Journal, A.I., Singh, D., Singh, S., Sahu, J., Srivastava, S., Singh, D., et al.. Ceramic nanoparticles: Recompense, Cellular Uptake and Toxicity Concerns Ceramic Nanoparticles: Recompense, Cellular Uptake and Toxicity Concerns, 2016. https://doi.org/10.3109/21691401.2014.955106 [24] D. Press. Silica nanoparticles induce oxidative stress, inflammation, and endothelial dysfunction in vitro via activation of the MAPK/Nrf2 pathway and nuclear factor- κ B signalling, 2015. [25] M. Mukhtar, M. Arshad, M. Ahmad, R.J. Pomerantz, B. Wigdahl, Z. Parveen, Antiviral potentials of medicinal plants, Virus Res. 131 (2) (2008) 111 120. Available from: https://doi.org/10.1016/j.virusres.2007.09.008. [26] Dillard, C.J., & German, J.B. Nutraceuticals and human health, 1756(May), 2021 https://doi.org/10.3390/ books978-3-0365-0445-2 [27] P. Blasi, Poly(lactic acid)/poly(lactic-co-glycolic acid)-based microparticles: an overview, J. Pharm. Investig. 49 (4) (2019) 337 346. Available from: https://doi.org/10.1007/s40005-019-00453-z. [28] L. Hu, X. Tang, F. Cui, Solid lipid nanoparticles (SLNs) to improve oral bioavailability of poorly soluble drugs, J. Pharm. Pharmacol. 103 (2004) 1527 1535. Available from: https://doi.org/10.1211/0022357044959. [29] S. Ju, J. Mu, T. Dokland, X. Zhuang, Q. Wang, H. Jiang, et al., Grape exosome-like nanoparticles induce intestinal stem cells and protect mice from DSS-induced colitis, Mol. Ther. 21 (7) (2013) 1345 1357. Available from: https://doi.org/10.1038/mt.2013.64. [30] S. Paul, P. Basak, R. Majumder, A. Mukherjee, J. Ghosh, S. Patra, et al., Biochemical estimation of Moringa oleifera leaf extract for synthesis of silver nanoparticle mediated drug delivery system, J. Plant Biochem. Biotechnol. 29 (1) (2020) 86 93. Available from: https://doi.org/10.1007/s13562-019-00517-z.

Green Chemistry Approaches to Environmental Sustainability

160

8. Plant-derived compounds and their green synthesis in pharmaceuticals and nutraceuticals

[31] A.K. Sharma, A.K. Swami, D. Jangir, M. Saran, T.K. Upadhyay, R.K. Prajapat, et al., An eco-friendly green synthesis of tungsten nanoparticles from Moringa oleifera lam. And their pharmacological studies, Gazi Med. J. 31 (4A) (2020) 719 725. Available from: https://doi.org/10.12996/GMJ.2020.167. [32] S. Sasidharan, L. Pottail, Antimicrobial activity of metal and non-metallic nanoparticles from Cyperus rotundus root extract on infectious disease causing pathogens, J. Plant. Biochem. Biotechnol. 29 (1) (2020) 134 143. Available from: https://doi.org/10.1007/s13562-019-00523-1. [33] K. Adavallan, N. Krishnakumar, Mulberry leaf extract mediated synthesis of gold nanoparticles and its antibacterial activity against human pathogens, Adv. Nat. Sciences: Nanosci. Nanotechnol. 5 (2) (2014). Available from: https://doi.org/10.1088/2043-6262/5/2/025018. [34] U. Suresh, K. Murugan, G. Benelli, M. Nicoletti, D.R. Barnard, C. Panneerselvam, et al., Tackling the growing threat of dengue: Phyllanthus niruri-mediated synthesis of silver nanoparticles and their mosquitocidal properties against the dengue vector Aedes aegypti (Diptera: Culicidae), Parasitol. Res. 114 (4) (2015) 1551 1562. Available from: https://doi.org/10.1007/s00436-015-4339-9. [35] R.V. Rane, K. Meenakshi, M. Shah, I.A. George, Biological synthesis of silver nanoparticles using Abelmoschus moschatus, Indian. J. Biotechnol. 13 (3) (2014) 342 346. [36] X. Wen, Q. Wang, T. Dai, J. Shao, X. Wu, Z. Jiang, et al., Identification of possible reductants in the aqueous leaf extract of mangrove plant Rhizophora apiculata for the fabrication and cytotoxicity of silver nanoparticles against human osteosarcoma MG-63 cells, Mater. Sci. Eng. C. 116 (2020) 111252July. Available from: https://doi.org/10.1016/j.msec.2020.111252. [37] K. Murugan, C. Panneerselvam, J. Subramaniam, P. Madhiyazhagan, J.S. Hwang, L. Wang, et al., Ecofriendly drugs from the marine environment: spongeweed-synthesized silver nanoparticles are highly effective on Plasmodium falciparum and its vector Anopheles stephensi, with little non-target effects on predatory copepods, Environ. Sci. Pollut. Res. 23 (16) (2016) 16671 16685. Available from: https://doi.org/ 10.1007/s11356-016-6832-9. [38] S. Rajput, D. Kumar, V. Agrawal, Green synthesis of silver nanoparticles using Indian Belladonna extract and their potential antioxidant, anti-inflammatory, anticancer and larvicidal activities, Plant. Cell Rep. 39 (7) (2020) 921 939. Available from: https://doi.org/10.1007/s00299-020-02539-7. [39] K. Elangovan, D. Elumalai, S. Anupriya, R. Shenbhagaraman, P.K. Kaleena, K. Murugesan, Phyto mediated biogenic synthesis of silver nanoparticles using leaf extract of Andrographis echioides and its bio-efficacy on anticancer and antibacterial activities, J. Photochem. Photobiol. B: Biol. 151 (2015) 118 124. Available from: https://doi.org/10.1016/j.jphotobiol.2015.05.015. [40] J. Santhoshkumar, S.V. Kumar, S. Rajeshkumar, Synthesis of zinc oxide nanoparticles using plant leaf extract against urinary tract infection pathogen, Resource-Efficient Technol. 3 (4) (2017) 459 465. Available from: https://doi.org/10.1016/j.reffit.2017.05.001. [41] P. Tippayawat, N. Phromviyo, P. Boueroy, A. Chompoosor, Green synthesis of silver nanoparticles in aloe vera plant extract prepared by a hydrothermal method and their synergistic antibacterial activity, PeerJ 2016 (10) (2016) 1 15. Available from: https://doi.org/10.7717/peerj.2589. [42] G. Campillo, G. Morales, J. Osorio, Silver nanoparticles (AgNPs) obtained by aqueous or ethanolic Aloe vera extracts: An assessing of the antibacterial activity and mercury remove capability, J. Nanomaterals 2018 (2018) 1 18. [43] B.A. Nancy, K. Elumalai, Synthesis of silver nanoparticles using Pelargonium graveolens essential oil and antifungal activity, Int. J. Pharm. Biol. Sci. 9 (2019) 176 185. [44] A.W. Bere, O. Mulati, J. Kimotho, F. Ng’Ong’A, Carica papaya leaf extract silver synthesized nanoparticles inhibit dengue type 2 viral replication in vitro, Pharmaceuticals 14 (8) (2021). Available from: https://doi. org/10.3390/ph14080718. [45] L. Gunti, R.S. Dass, N.K. Kalagatur, Phytofabrication of selenium nanoparticles from emblica officinalis fruit extract and exploring its biopotential applications: antioxidant, antimicrobial, and biocompatibility, Front. Microbiol. 10 (2019) 1 17. Available from: https://doi.org/10.3389/fmicb.2019.00931. APR. [46] P. Goyal, A. Bhardwaj, B.K. Mehta, D. Mehta, Research article green synthesis of zirconium oxide nanoparticles (ZrO2NPs) using Helianthus annuus seed and their antimicrobial effects, J. Indian Chem. Soc. 98 (8) (2021) 100089. Available from: https://doi.org/10.1016/j.jics.2021.100089. [47] W. Muhammad, M.A. Khan, M. Nazir, A. Siddiquah, S. Mushtaq, S.S. Hashmi, et al., Papaver somniferum L. mediated novel bioinspired lead oxide (PbO) and iron oxide (Fe2O3) nanoparticles: in-vitro biological

Green Chemistry Approaches to Environmental Sustainability

References

[48]

[49]

[50]

[51]

[52]

[53]

[54] [55]

[56]

[57]

[58]

[59]

[60] [61]

[62]

[63] [64]

161

applications, biocompatibility and their potential towards HepG2 cell line, Mater. Sci. Eng. C. 103 (2019) 109740May. Available from: https://doi.org/10.1016/j.msec.2019.109740. M. Mani, S. Pavithra, K. Mohanraj, S. Kumaresan, S.S. Alotaibi, M.M. Eraqi, et al., Studies on the spectrometric analysis of metallic silver nanoparticles (Ag NPs) using Basella alba leaf for the antibacterial activities, Environ. Res. 199 (2021) 111274April. Available from: https://doi.org/10.1016/j.envres.2021.111274. N. Chauhan, A.K. Tyagi, P. Kumar, A. Malik, Antibacterial potential of Jatropha curcas synthesized silver nanoparticles against food borne pathogens, Front. Microbiol. 7 (2016) 1 13NOV. Available from: https:// doi.org/10.3389/fmicb.2016.01748. S. Vimalraj, T. Ashokkumar, S. Saravanan, Biogenic gold nanoparticles synthesis mediated by Mangifera indica seed aqueous extracts exhibits antibacterial, anticancer and anti-angiogenic properties, Biomed. Pharmacotherapy 105 (2018) 440 448May. Available from: https://doi.org/10.1016/j.biopha.2018.05.151. H. Qamar, S. Rehman, D.K. Chauhan, A.K. Tiwari, V. Upmanyu, Green synthesis, characterization and antimicrobial activity of copper oxide nanomaterial derived from Momordica charantia, Int. J. Nanomed. 15 (2020) 2541 2553. Available from: https://doi.org/10.2147/IJN.S240232. P.G. Bhavyasree, T.S. Xavier, Green synthesised copper and copper oxide based nanomaterials using plant extracts and their application in antimicrobial activity: Review, Curr. Res. Green. Sustain. Chem. 5 (2022) 100249September 2021. Available from: https://doi.org/10.1016/j.crgsc.2021.100249. L. Wang, C. Hu, L. Shao, The-antimicrobial-activity-of-nanoparticles present-situati, Int. J. Nanomed. 12 (2017) 1227 1249. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5317269/pdf/ijn-121227.pdf. P.V. AshaRani, M.P. Hande, S. Valiyaveettil, Anti-proliferative activity of silver nanoparticles, BMC Cell Biol. 10 (2009) 65. Available from: https://doi.org/10.1186/1471-2121-10-65. S. Hua, M.B.C. de Matos, J.M. Metselaar, G. Storm, Current trends and challenges in the clinical translation of nanoparticulate nanomedicines: pathways for translational development and commercialization, Front. Pharmacol. 9 (2018) 1 14Issue JUL. Available from: https://doi.org/10.3389/fphar.2018.00790. R. Bhat, V.G. Sharanabasava, R. Deshpande, U. Shetti, G. Sanjeev, A. Venkataraman, Photo-bio-synthesis of irregular shaped functionalized gold nanoparticles using edible mushroom Pleurotus florida and its anticancer evaluation, J. Photochem. Photobiol. B: Biol. 125 (2013) 63 69. Available from: https://doi.org/10.1016/j. jphotobiol.2013.05.002. V. Wilhelmi, U. Fischer, H. Weighardt, K. Schulze-Osthoff, C. Nickel, B. Stahlmecke, et al., Zinc Oxide nanoparticles induce necrosis and apoptosis in macrophages in a p47phox- and Nrf2-independent manner, PLoS ONE 8 (6) (2013) 1 15. Available from: https://doi.org/10.1371/journal.pone.0065704. M.Z. Iqbal, W. Ren, M. Saeed, T. Chen, X. Ma, X. Yu, et al., A facile fabrication route for binary transition metal oxide-based Janus nanoparticles for cancer theranostic applications, Nano Res. 11 (10) (2018) 5735 5750. Available from: https://doi.org/10.1007/s12274-017-1628-x. M.N. Vu, H.G. Kelly, S.J. Kent, A.K. Wheatley, Current and future nanoparticle vaccines for COVID-19, EBioMedicine, Vol. 74, Elsevier B.V, 2021, p. 103699. Available from: https://doi.org/10.1016/j. ebiom.2021.103699. J. RC, Plant extracts based nanoparticles, potential nanomedicine in fight against COVID-19, J. Nanosci. Res. & Rep. 2 (4) (2020) 1 4. Available from: https://doi.org/10.47363/jnsrr/2020(2)116. K.J. Hager, G.P. Marc, P. Gobeil, R.S. Diaz, G. Heizer, C. Llapur, et al. Efficacy and Safety of a Plant-Based Virus-Like Particle Vaccine for COVID-19 Adjuvanted with AS03. 2022. MedRxiv, 2022.01.17.22269242. https://www.medrxiv.org/content/10.1101/2022.01.17.22269242v1%0Ahttps://www.medrxiv.org/content/ 10.1101/2022.01.17.22269242v1.abstract. S. Prabha, D. Durgalakshmi, S. Rajendran, E. Lichtfouse, Plant-derived silica nanoparticles and composites for biosensors, bioimaging, drug delivery and supercapacitors: a review, Environ. Chem. Lett. 19 (Issue 2) (2021) 1667 1691Springer International Publishing. Available from: https://doi.org/10.1007/s10311-02001123-5. S.K. Jha, P. Roy, S. Chakrabarty, Nutraceuticals with pharmaceutics: its importance and their applications, Int. J. Drug. Dev. Res. 13 (S3) (2021) 002. A.R. Singh, P.K. Desu, R.K. Nakkala, V. Kondi, S. Devi, M.S. Alam, et al., Nanotechnology-based approaches applied to nutraceuticals, Drug. Delivery Transl. Res. 12 (3) (2022) 485 499. Available from: https://doi.org/ 10.1007/s13346-021-00960-3.

Green Chemistry Approaches to Environmental Sustainability

162

8. Plant-derived compounds and their green synthesis in pharmaceuticals and nutraceuticals

[65] N. Pandey, D. Barve, T.I.T.C.O. Pharmacy, A. Nagar, M.P. Bhopal, Review paper phytochemical and pharmacological review on Annona squamosa Linn, Int. J. Res. Pharm. Biomed. Sci. 2 (4) (2011) 1404 1412. [66] E.A.N.N. Conover, N. Teratogen, I. Service, Over-the-counter products: nonprescription, Clin. Obstet. Gynecol. 45 (1) (2002) 89 98. [67] J. Huang, Q. Wang, T. Li, N. Xia, Q. Xia, Nanostructured lipid carrier (NLC) as a strategy for encapsulation of quercetin and linseed oil: preparation and in vitro characterization studies, J. Food Eng. 215 (2017) 1 12. Available from: https://doi.org/10.1016/j.jfoodeng.2017.07.002. [68] E. Assadpour, S. Mahdi Jafari, A systematic review on nanoencapsulation of food bioactive ingredients and nutraceuticals by various nanocarriers, Crit. Rev. Food Sci. Nutr. 59 (19) (2019) 3129 3151. Available from: https://doi.org/10.1080/10408398.2018.1484687. [69] M.C. Cristiano, F. Froiio, A. Mancuso, D. Cosco, L. Dini, L. Marzio, et al., Oleuropein-laded ufasomes improve the nutraceutical efficacy, Nanomaterials 11 (1) (2021) 1 16. Available from: https://doi.org/ 10.3390/nano11010105. [70] M. Fresta, A. Mancuso, M.C. Cristiano, K. Urbanek, F. Cilurzo, D. Cosco, et al., Targeting of the pilosebaceous follicle by liquid crystal nanocarriers: In vitro and in vivo effects of the entrapped minoxidil, Pharmaceutics 12 (11) (2020) 1 22. Available from: https://doi.org/10.3390/pharmaceutics12111127. [71] B. Rasti, A. Erfanian, J. Selamat, Novel nanoliposomal encapsulated omega-3 fatty acids and their applications in food, Food Chem. 230 (2017) 690 696March. Available from: https://doi.org/10.1016/j. foodchem.2017.03.089. [72] N.P. Aditya, Y.G. Espinosa, I.T. Norton, Encapsulation systems for the delivery of hydrophilic nutraceuticals: food application, Biotechnol. Adv. 35 (4) (2017) 450 457. Available from: https://doi.org/10.1016/j. biotechadv.2017.03.012. [73] A. Ali, U. Ahmad, J. Akhtar, Badruddeen, M.M. Khan, Engineered nano scale formulation strategies to augment efficiency of nutraceuticals, J. Funct. Foods 62 (2019) 103554June. Available from: https://doi.org/ 10.1016/j.jff.2019.103554. [74] P. Basnet, N. Skalko-Basnet, Curcumin: an anti-inflammatory molecule from a curry spice on the path to cancer treatment, Molecules 16 (6) (2011) 4567 4598. Available from: https://doi.org/10.3390/ molecules16064567. [75] A. Anwar, A. Masri, K. Rao, K. Rajendran, N.A. Khan, M.R. Shah, et al., Antimicrobial activities of green synthesized gums-stabilized nanoparticles loaded with flavonoids, Sci. Rep. 9 (1) (2019) 1 12. Available from: https://doi.org/10.1038/s41598-019-39528-0. [76] A.Y. Berman, R.A. Motechin, M.Y. Wiesenfeld, M.K. Holz, The therapeutic potential of resveratrol: a review of clinical trials, Npj Precis. Oncol. 1 (1) (2017). Available from: https://doi.org/10.1038/s41698-017-0038-6. [77] V. da Silva Santos, A.P. Badan Ribeiro, M.H. Andrade Santana, Solid lipid nanoparticles as carriers for lipophilic compounds for applications in foods, Food Res. Int. 122 (2019) 610 626January. Available from: https://doi.org/10.1016/j.foodres.2019.01.032. [78] F. Tamjidi, M. Shahedi, J. Varshosaz, A. Nasirpour, Nanostructured lipid carriers (NLC): a potential delivery system for bioactive food molecules, Innovative Food Sci. Emerg. Technol. 19 (2013) 29 43. Available from: https://doi.org/10.1016/j.ifset.2013.03.002. [79] A.R. Neves, S. Martins, M.A. Segundo, S. Reis, Nanoscale delivery of resveratrol towards enhancement of supplements and nutraceuticals, Nutrients 8 (3) (2016) 1 14. Available from: https://doi.org/10.3390/ nu8030131. [80] C. Has, P. Sunthar, A comprehensive review on recent preparation techniques of liposomes, J. Liposome Res. 30 (4) (2020) 336 365. Available from: https://doi.org/10.1080/08982104.2019.1668010. [81] M. Manconi, F. Marongiu, I. Castangia, M.L. Manca, C. Caddeo, C.I.G. Tuberoso, et al., Polymer-associated liposomes for the oral delivery of grape pomace extract, Colloids Surf. B: Biointerfaces 146 (2016) 910 917. Available from: https://doi.org/10.1016/j.colsurfb.2016.07.043. [82] D. Raffa, B. Maggio, M.V. Raimondi, F. Plescia, G. Daidone, Recent discoveries of anticancer flavonoids, Eur. J. Med. Chem. 142 (2017) 213 228. Available from: https://doi.org/10.1016/j.ejmech.2017.07.034. [83] R. Vinayagam, B. Xu, Antidiabetic properties of dietary flavonoids: a cellular mechanism review, Nutr. Metab. 12 (1) (2015) 1 20. Available from: https://doi.org/10.1186/s12986-015-0057-7.

Green Chemistry Approaches to Environmental Sustainability

References

163

[84] I. Ioannou, N. M’hiri, H. Chaaban, N.M. Boudhrioua, M. Ghoul, Effect of the process, temperature, light and oxygen on naringin extraction and the evolution of its antioxidant activity, Int. J. Food Sci. Technol. 53 (12) (2018) 2754 2760. Available from: https://doi.org/10.1111/ijfs.13887. [85] J. Maduni´c, I.V. Maduni´c, G. Gajski, J. Popi´c, V. Garaj-Vrhovac, Apigenin: a dietary flavonoid with diverse anticancer properties, Cancer Lett. 413 (2018) 11 22. Available from: https://doi.org/10.1016/j. canlet.2017.10.041. [86] M. Huang, E. Su, F. Zheng, C. Tan, Encapsulation of flavonoids in liposomal delivery systems: the case of quercetin, kaempferol and luteolin, Food Funct. 8 (9) (2017) 3198 3208. Available from: https://doi.org/ 10.1039/c7fo00508c. [87] S.M. Chacko, P.T. Thambi, R. Kuttan, I. Nishigaki, Beneficial effects of green tea: a literature review, Chin. Med. 5 (2010) 1 9. Available from: https://doi.org/10.1186/1749-8546-5-13. [88] A. Karthikeyan, N. Senthil, T. Min, Nanocurcumin: a promising candidate for therapeutic applications, Front. Pharmacol. 11 (2020) 1 24May. Available from: https://doi.org/10.3389/fphar.2020.00487.

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C H A P T E R

9 Radioactive waste minimization and management Pradeep Kumar1, Sushma Yadav1 and Anoop Yadav2 1

Industrial Waste Management, Department of Vocational Studies and Skill Development, Central University of Haryana, Mahendergarh, Haryana, India 2Department of Environmental Studies, Central University of Haryana, Mahendergarh, Haryana, India

9.1 Introduction Nuclear power generation, nuclear fission and various other applications, that is, research and medicine are responsible for generating radioactive waste. One major challenge humans and the environment face is properly managing the radioactive waste. Almost every industry activity produces some amount of waste. The radiations emitted by radioactive waste greatly danger the living beings, which is likely to continue for subsequent generations. The radioactive waste includes contaminated clothes, swabs, rags, filters, needles, mop heads and tissues from lab animals. Research chemicals and scintillation fluids are examples of liquid radioactive waste. From little over natural background levels to extremely radioactive, radioactivity can take many different forms. Radioisotopes included 1251 (25.5%), "P (19.1%), "H (14.5%), "C (8.7%), "S (6.2%), 1 (1.1%), "Cr (0.8%) and several others in a study of radioactive waste [1]. It is regulated by government agencies in every country to protect all forms of life and the environment. The AERB (Atomic Energy Regulatory Board) regulates the storage, management and disposal of generated radioactive waste. The major challenge with radioactive waste is the decay of radioactivity with time so the waste has to be stored in any appropriate disposal facility for a sufficient period of time until it has no threats to the environment. The radioactivity of radioactive waste may be different; depending on the radioactivity, the waste may remain radioactive for some days, months, or years. Because of the serious lack of fossil resources, man must consider alternative energy sources in order to survive. It is essential to consider an alternative source of energy given the fast-growing economies and rising energy demand. Uranium is now the only practical

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alternative fuel utilized in atomic reactors, where it is used to generate electricity through nuclear fission. Although a very small amount of this fuel can provide tremendous energy fluxes, there are additional issues that can arise while producing power from this source. The risk posed by radioactive radiation is one of the most crucial factors to take into account while designing, constructing and successfully operating a nuclear plant. The disposal of radioactive material after usage is a problem that is more prevalent than nuclear radiation. From a tiny operation comprising individuals who initially had little to no specialized expertise in radioactive pollution, the management of radioactive wastes has progressed. In certain nations, managing radioactive waste is a lucrative industry and a full-time vocation including both research and fieldwork. Since the discovery of artificial radioactivity, notably as a result of the development of the atomic bomb, hydrogen bomb and nuclear energy techniques, the threat of radioactive pollution spreading into the environment has significantly increased. In fact, waste streams and stack gases from the operations of power processing plants release this hazardous pollution into the environment. Heavy radionuclides are created by the neutron bombardment of atomic fuel and are exceedingly hazardous. Once in the environment, these radioactive elements enter eco-cycling processes before eventually entering the food chain and metabolic pathways. The ecology and the next generation are seriously threatened by radioactive pollution. However, radioactive wastes from nuclear facilities, reactors, etc., are a particular kind in that they are exceedingly dangerous to living things even in minute quantities and do not smell terrible or harm the environment like smoke. These wastes last a very long time in the environment. Nonradiation contaminants and radionuclides with short half-lives are continuously released into the atmosphere, and it is anticipated that they will disperse or decay quickly. As a result, they are not considered a threat to future pollution until their concentration goes over the limit. The same as other industrial wastes, they cannot be dumped into the environment. The disposal of the numerous types of solid and liquid radioactive waste produced by nuclear facilities, each of which contains varying levels of radioactivity, requires special consideration. Nuclear waste and radioactive pollution royal disposal techniques are needed for the management of radioactive waste. Some naturally unstable elements have a tendency to become stable during radioactivity by producing alpha, beta and gamma rays. When these rays pass through a cell, they can ionize the air and disrupt the cell’s metabolic processes. A considerably more thorough cost benefit analysis must be done when choosing a specific waste management system, such as the type of nuclear power plant to use. To convey such a verdict in numbers, however, has been impossible up until now due to a fundamental problem. A fraction must have the same units used to describe both the numerator and the denominator. The majority of nuclear power’s advantages should be able to be communicated, but if its cost is seen as a rise in the likelihood that people would contract cancer or live shorter lives, how can it be expressed in monetary terms? A true cost benefit analysis is preferable to a pipe dream, so those in charge of authorizing a new power station or a waste disposal programme must ultimately make a value judgement that is, at the very least, somewhat subjective. A national atomic energy authority is often in charge of making decisions regarding issues relating to “engaging in”, that is, carrying out anything with radioactive elements,

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electromagnetic radiation-producing apparatus and specific substances planned like heavy water. An impartial advisory group, which has the option to enlist the help of a knowledgeable staff, provides assistance to the authority in evaluating the risks associated with reactors and other installations, such as waste management systems. Compared to wastes produced by nuclear fuel cycle activities, radioactive waste generated by the healthcare industry does not present a substantial long-term waste management challenge. The short half-life and low radiotoxicity of biomedical waste are two of its most significant qualities. Biomedical waste typically has low total and specific activity, low energy content and low emissions. The amount of trash generated as well as other hazardous characteristics, such as biological and chemical concerns, should be taken into account. An efficient programme for managing biomedical radioactive waste is one that adheres to the regulatory authority’s standards for personnel and environmental protection while focusing on waste minimization and avoidance. All related risks detected in the garbage should be integrated into this management.

9.2 Sources of nuclear wastes 9.2.1 Mining and milling of uranium In addition to the typical risks connected with hard rock mining, uranium mine employees are also exposed to radon and the by-products of the ore’s radium decay. These risks can be reduced by caulking old workings, practicing general "good housekeeping", installing an effective ventilation system and using respirators as necessary. The ventilation air contains dust and radioactive particles, among which several are filtered out, if required, although radon is still present. The enormous amount of air, a stack, is used to discharge mining vents at high speeds, providing proper diffusion into the atmosphere. The mill’s final outputs are uranium oxide "tailings". The majority of the radium that was previously present in the ore is now found in the tailings and mine drainage water. One of the most dangerous radionuclides is radium, which presents a significant risk. Most of the radium is rendered insoluble through various treatment processes, such as coprecipitation with barium, and considerably more radium than permitted in drinking water is frequently present in the water draining from tailing ponds. Adequate dilution can be achieved through the design of outfalls into appropriate bodies of water, although caution is required to avoid tailings pond rupture or improper operations that would invalidate or bypass the treatment system. Initially, in the development of the sector, the risks were either underappreciated or disregarded, which led to the contamination of lakes and streams in places with active uranium mining. Today, monitoring systems for downstream water and fish analysis are ubiquitous.

9.2.2 Processing of uranium oxides The processing mills may transform the crude (70%) U, O they generate into metal, UO or UF. Hexafluoride is used to separate U 235 (a fissionable isotope of uranium with a natural abundance of 17% 0.7%). Nuclear fission would provide a significant waste issue if a

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significant amount of 235 were to unintentionally gather in one location. However, it is extremely unlikely that this can happen. The wastes are made up of uranium chips and fines, tainted clothing, contaminated respirators and dust that has accumulated in aircleaning systems, among other things. At this point, the uranium is almost completely free of radium, making it hardly a radioactive threat. Natural uranium, or 238U, has the toxicity of a poisonous metal rather than a radionuclide. Transformation of uranium oxide by reducing the dioxide to tetrafluoride, which is subsequently reduced to the uranium metal at a high temperature ( . 1300 C) with a reducing agent i.e. magnesium. Due to its limited solubility in water, the debris from this process, which includes magnesium fluoride slag and uranium metal fines from trimming the ingots, presents a typical slag disposal challenge.

9.2.3 Fuel fabrication Although there are a number of distinct types of fuel elements, only dust and damaged fuel pins or pellets are left over after their production. Usually, these elements are recycled.

9.2.4 Reactor wastes An enormous amount of fission products is present in a functioning reactor. After 180 days of operation, a 500 MW (thermal) reactor contains 400 million curies of fission products, monitored 1 day after closing. This corresponds to around 400 metric tonnes of radium activity. Initially, the fission products degrade quickly, leaving 80 million curies after 1 week, and then more gradually. The stock is down to roughly 8 million curies after a month. Nuclear power plants with an electrical rating of 1000 MW, or 3000 5000 MW thermals, are common. These plants initially appear to be massive potential suppliers of radioactive wastes, but in reality, this is not the case. A noncorrodible cladding, often made of zirconium or stainless steel, surrounds the fuel in an operational power reactor, preventing fission products from escaping unless the cladding is breached. Radiation leaks from the main cooling circuit due to leaks from a few fuel elements, yet it is still viable to run the reactor with these flaws. High radiation fields make it impossible to run a station; therefore ion exchangers are constantly purifying the main coolant. The ion exchangers must be replaced basically as soon as they reach a particular radiation threshold, to reiterate. The end result of these factors is that if there is more rupture fuel than a tiny amount in a reactor, it will need to be removed for reasons of operator safety and cost. In order to allow for the decay of transient radioactivity, discarded reactor fuel is often kept on site for a long period of time. Typically, storage facilities are large, water-filled tanks that serve as both a radiation shield and a cooling. Even if there are no cladding problems, the water in cooling ponds still becomes polluted with radioactive substances over time if there is defective fuel present. This is due to the fact that the reactor’s cladding and structure add neutron activation products (also known as corrosion products) to the cooling water and that the cladding itself always has trace amounts of uranium that fissions in

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the reactor. As a result, the pond water needs to be cleaned, typically using resin ion exchangers, and these resins end up as trash as well. Regenerated resins (acids, alkalis or salts) will manifest as a liquid waste that needs to be disposed of. In the absence of that, the resin will be handled in that container, or as a powder or slurry. The architecture of the reactor affects how radioactive the gaseous effluents from reactors are. Very significant amounts of argon-41 may be released from the stack if air flows through the core. Despite being a hard gamma emitter, Ar 41 only has a 2-hour half-life, therefore its effects are only felt inside or very close to the plant. Nitrogen and oxygen radioactive isotopes decay so quickly that they do not accumulate in the stack, and the long-lived carbon-14 is not created in quantities great enough to pose a risk at the current level of nuclear power production. The seriousness of a radioactive waste source depends on whether one is thinking about the safety of those within the facility or the general public outside. For instance, iodine and other radioactive fission products might become airborne due to ruptured fuel components or routine mechanical problems, which is a hassle for operators who must wear plastic suits and respirators while working. These sources are minor beyond the exclusion zone due to the ventilation filtration system and the atmosphere’s great dispersion capacity. However, they may substantially affect station productivity and work schedules, and they may result in significant disposals of contaminated clothing, mop heads and metal scrap due to clean-up procedures. Tritium, which collects in heavy-water reactors’ coolant and moderators, is a notable source of this kind. The optimum tritium levels in the moderator of a 1000 MW (electrical) power station are roughly 50 Ci/L. This causes very little stack discharges, but any leaks in the station’s pump seals, valves, or pipe joints would cause operational issues for those in charge of the staff’s radiation protection. Materials transported for waste disposal would not cause an issue because tritium has substantially higher maximum permitted amounts in air and water than the majority of other radionuclides. This is due in part to the fact that heavy water is recovered for economic reasons as well as the fact that tritium is a radionuclide. When compared to waste produced by a research and development facility and a spent fuel processing plant, the amount produced in power stations is negligible. This statement applies to all aspects of regular operation, including common mishaps and accidents that can be anticipated in any well-designed factory. The “maximum credible accident” effects are not included because they are so unlikely that waste management system designers rarely account for them.

9.2.5 Spent fuel processing More than 99.9% of the "waste disposal problem" is caused by wastes from processing used fuel. The fuel is de-sheathed and dissolved after being removed from the reactor and kept in storage long enough for short-lived fission products to decompose. The fission products left over after uranium and plutonium have been recovered into an organic solvent from the high-level or main waste. Medium-level wastes are created by washing the organic extractor, while low-level wastes are made up of additional liquids from different sources to count, including washings, cooling water, scrubbing water and more.

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Tritium, Bromines, Iodines, Xenon, Krypton and smaller quantities of less volatile elements like ruthenium and Cesium are all present in the gases that come from the dissolvers and storage tanks. Off-gases can be released from a tall stack after being stored for decay, cleaned and filtered. As was indicated in the section on reactors, if better containment is not provided in a timely manner at spent fuel processing sites, the expansion of fuel processing plants in the future could theoretically result in local or even eventual global atmospheric pollution (Fig. 9.1). Glasses and ceramics, which are utilized to fix the activity in high-level liquid wastes, as well as bitumen or concrete blocks containing a less active material, can be considered solid waste. Products of waste processing include radioactive materials, nitric acid dissolver and nuclear pollution. The medium-level category typically includes wastes including sludges, evaporator bottoms, incinerator ash, adsorbers, filters and scrap fuel cladding. Inoperable protective gear, clean-up supplies, damaged pipes, tanks and valves, as well as entire structures, may be contaminated to varying degrees by a range of radionuclides, making it impossible to quantify. Since the majority of these wastes need to be confined in some form and none of them are thrown into the environment, this is not a major problem, except for administrative and recording needs when quantitative reports need to be generated. Not off-gases, heterogeneous polluted scrap, or high or medium-level waste are the industry’s most challenging issues. Due to its massive volume, very low-level liquid waste is the major issue. Every year, billions of gallons of low-level and mainly unpolluted but suspect waste are produced from a variety of sources, such as cooling and final washing water, effluents from laundries and decontamination facilities, floor draining from cleanup efforts, personnel shower drainage and effluent from liquid waste filtering plants’ final stages. Although some countries massively evaporate these effluents, they are mainly

FIGURE 9.1 Diagram of fuel processing plant.

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dumped into the environment in other ways. High-level, moderate-level and low-level radioactive wastes can all be grouped together. 9.2.5.1 Health impact of radioactive pollution All of us are vulnerable to some radiation levels. The majority of background radiation is produced by radon, which is created by the rocks that make up our planet’s crust. A very small percentage (1%), including atmospheric testing of atomic weapons, comes from the nuclear industry as a whole. A lesser portion (16%) is derived from artificial sources, primarily medical exposures. The average annual dose of background radiation is about 2.4 mSv; however, the number may be as high as 50 mSv depending on the topography and elevation of the region where an individual lives. The greatest known background radiation exposure levels that significantly influence a community are in the Indian states of Kerala and Madras, where over 140 000 persons receive gamma radiation doses on average of over 15 mSv/year in addition to radon doses of a comparable magnitude. Similar amounts are present in Sudan and Brazil, where the average age exposure for many people is up to roughly 40 mSv/ year. If each person received the average annual dosage of 2 mSv, they would have collected 160 mSv of radiation from natural sources if they lived to be 80 years old. The two categories of radiation’s health effects exhibit slightly distinct connections between dose and effect. Early, deterministic or tissue effects are observed at high doses ( . 1 Sv), are linked to cell death in the exposed tissues and exhibit a dose-dependent relationship. We are accustomed to seeing these side effects in cancer patients who have received radiation treatment—vomiting, diarrhoea, hair loss, etc. Lower doses, where the dose is connected with the probability of the effect rather than the dose itself, are where the longer-term or stochastic effects are observed. Cancer is the stochastic effect that most concern the general population. The lifespan studies, which were started after the atomic bombs were dropped on Japan in 1945, provide the majority of the data on the health consequences of radiation in healthy populations. These cohorts were put together in 1950 and have been monitored for 65 years. Of the original 120,000 individuals, 54,000 were within 2.5 km of the explosion’s epicenter and 45,000 were between 2.5 and 10 km away. Approximately 40% of people are still living. The control population (26,000 people) resided in Hiroshima or Nagasaki between 1951 and 1953 but was not present during the explosions. For 92% of the population, individual dose estimates are available. Some survivors received over 2 Gy, and the mean dose was 200 mSv. Recent reviews of these research findings were published by [2]. The results from the lower dosage range of the lifespan research are supported by a number of other sizable cohort studies involving both acute and long-term radiation exposures. These include the Techa River people whose cohorts cleaned it up after the Chornobyl tragedy exposed them to radioactive waste material flowing into the river near their homes [3,4], and the National Registry of Radiation Workers (NRRW), a study of UK nuclear workers. Additionally, data from Yangjiang, a region in China with significant natural background radiation, as well as from BNFL employees, are available [5]. It should be emphasized that most estimates of excess relative risk are close to 0, especially for doses between 0 and 0.1 Sv. In most cases, the 95% confidence intervals (if provided) also fall within this range. This shows that there is not any statistical support for the effect of

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radiation at these levels being established scientifically; instead, it might just be a coincidental correlation [6]. The only radiobiological consequence of the Chernobyl accident that has been proven to have affected the general population is a rise in thyroid cancer among people who were young at the time of the disaster. Although thyroid cancer rates have returned to preaccident levels for people born after 1987, when radioactive iodine was removed from the environment, the increase was swift and is still noticeable today [7]. When compared to agematched controls, radiation-induced thyroid cancer appears to have few differences in terms of form or clinical outcome. Thyroid cancer is very treatable, and although 30% of patients may experience a relapse, just 1% may ultimately pass away from their condition. Only 15 of the approximately 6000 diagnosed cases since 1986 have so far been fatal [8].

9.3 Disposal guidelines Every human action that includes changing one thing into another must result in the trash. Energy can also be transformed from one form to another. An industry may be able to recycle some of its waste materials and transform some of them into useful forms, but there will always be a small amount of residue that cannot be kept in the system. This has to fit into the surroundings somehow. Discharging it in a method that assures sufficient dilution to render it harmless is typically the simplest procedure. If this is not feasible due to technological or political issues, it must be contained; however, generally speaking, the more effectively contained, the more expensive. Demanding a specific level of waste limitation or confinement implies acceptance of the waste management system’s cost as an important component of the process’s cost. To say that a process must be carried out with no waste is the same as saying that the process may not be carried out at all. Radioactive waste can be disposed of using one of three methods:

9.3.1 Isolation and concentration The sole extra criterion is "perpetual custody to ensure that the confinement is never broken" if wastes are actually confined, meaning that under no plausible circumstances could they be released into the environment. It is simpler to say than to do. Few commercial companies have a history of more than 100 years, political regimes have seldom lasted more than 500 years, and there are not many civilizations that have endured for more than 2000 years. What can be done to maintain permanent custody of wastes containing, for example, plutonium with a 24,000-year half-life? This question has an important implication. After our current civilization has vanished and possibly been forgotten, some of the wastes for which we are responsible will still be radioactive. As far as we are aware, there is no workable answer to the problem of solid and hazardous waste management. The most we can do is make sure that all significant disposals are documented in the closest thing we have to an eternal repository of archives, a government agency, including their kind, quantity and location.

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9.3.2 Dispersion and dilution The traditional technique that mankind has always used to dispose of their wastes is dilution and dispersion. Up until recently, the system appeared to function reasonably well unless the population became too concentrated, but it is now becoming apparent that there are so many people that the system is beginning to malfunction. It depends on the environment’s ability to dilute or detoxify the wastes to a level that is safe for people and creatures that are important to people.

9.3.3 Delay and decay It is feasible to turn some wastes into safe chemicals with very low radiation levels. Both liquid and gaseous wastes may be disposed of in this manner. It is feasible to store some wastes until their radiation level reaches a safe level as the radiation intensity gradually decreases over time. After that, it can be buried under a bunch of soil for disposal. The following three things determine whether a discharge is safe for the environment: 1. Dispersion by the use of techniques including air dilution, combining with water or spreading. 2. Fixation of radionuclides on organic debris and soil minerals. 3. Radionuclide decay, whether diffused or fixed before, may have an impact on people. Regulatory authorities have occasionally fallen into a logical fallacy with regard to the principle of dispersion. The concentration in the effluent pipe or the concentration at the stack mouth in some nations regulates the amount of liquid and gaseous waste that can be discharged. This is predicated on the notion that everything will be fine if the concentration is kept within the range of what is allowed. However, a river’s “dilution capacity” is determined by the daily water flow divided by the number of Curies that are added to the river each day. An operator only needs to double the water running through the pipe if he wants to dispose of twice as much garbage and is only constrained by the concentration in the effluent pipe. However, unless he doubled the river’s flow, the downstream consequence would be a doubling in the concentration. Because of this, restrictions must be set in Curies per unit time rather than microcuries per millilitre, and river flow volume must be considered if it varies seasonally. Only those who are close to the discharge site are protected by regulations that are based on concentration at the discharge point.

9.4 Disposal methods To assure that the primary focus is waste prevention and minimization while providing protection from all associated waste threats, a detailed preceding review is required for a comprehensive waste management programme. This evaluation will look at waste types and amounts produced, the total radionuclide inventory and use patterns, and prospective

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disposal routes. The radioactive waste generator will either hold low-level waste onsite until it has decomposed enough to be disposed of as regular trash or until there is enough to ship to a low-level waste disposal site in containers. The goal of this evaluation is to coordinate waste management practices across all divisions of a facility. The optimal time to do this review is when a facility is being planned since this will allow for the incorporation of specific elements that will improve waste management throughout the building. However, the evaluation will typically be done on an already-existing facility, which can contain individual laboratories with their own unique waste management procedures and guidelines. Harmonization of waste management practices is even more crucial in these situations. It is not possible to determine what waste minimization techniques need to be used or how waste management can be effectively structured until all radionuclide uses have been assessed.

9.4.1 Storage of liquid and solid wastes Due to the need for long-term storage of extremely large volumes (millions of gallons) of highly acidic waste, tankage and pipeline systems were developed. These systems have been resilient to harsh conditions for many years. While there have been failures, the environment has not been contaminated because of good design and well-chosen materials. Tanks are made of materials, frequently stainless steel, that won’t corrode from the solutions they’re meant to store. Catch tanks or drip trays serve as secondary containment, and enough spare tankage is maintained on hand to quickly empty a damaged tank. A monitoring device that detects leakage quickly issues an alert if radioactive liquid arrives in the catch tank. The active liquid is moved by pumping rather than by gravity to ensure that it was done on purpose and not by mistake.

9.4.2 Evaporation Evaporation is the most direct and, on the surface, the most basic technique of treatment for radioactive liquid wastes. The radioactive concentration of the distillate in a professionally constructed evaporator with an effective droplet de-entertainment system can be as little as one-millionth of that in the pot. There isn’t much in the design that is explicitly related to radioactivity, except for the possibility that operator shielding will need to be supplied, and the monitoring and potential treatment of off-gases. Evaporation is unfortunately expensive since it uses a lot of energy and the concentration it produces is still a radioactive liquid waste. Although evaporation to dryness or to the point of crystallization has been used, the residue is so soluble in water that it cannot be disposed of without further processing. The expense of evaporation may be justified by its numerous benefits in situations where the release of a significant amount of low-level waste into the environment is unacceptable. Evaporation is utilized extensively in Japan as well as Denmark and Sweden to treat nearly all liquid wastes. Evaporation leftovers can be fused with glass frit, various ceramic combinations or cement. They can also be combined with melted bitumen. After that, the product is treated as solid waste (Table 9.1).

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9.4 Disposal methods

TABLE 9.1 Represents different methods of radioactive waste disposal. Sr. no.

Method of radioactive waste disposal

Reference

1

Phytoextraction

[9]

2

Phytovolatilization

[10]

3

Phytostabilization

[11]

4

Rhizofiltration

[12]

5

Phytodegradation

[13]

9.4.3 Precipitation and flocculation Removal of the activity from some type of precipitate, either as an intrinsic component of the precipitated substance or adsorbed on its surface, is the most affordable and straightforward method for treating radioactive liquids. In most waste tanks, a sludge settles out, containing up to 90% of the activity, and upon neutralization, a thick precipitate of metallic hydroxides forms, containing up to 90% of the remaining activity. After these sludges have been separated, lime and sodium carbonate can be added to the clear effluent to further purify it. This treatment has the potential to eliminate up to 99% of the residual activity. Lime and sodium phosphate treatment is also highly efficient. The method of treatment is determined by the specific radionuclides found in the waste as well as by its overall composition, such as the pH and salt concentration of the solution. In other circumstances, clay, ferric chloride, or other additives are added at strategically placed intervals throughout the process. Specialized chemists must continuously analyse and monitor the process choice and any alterations made as the waste’s composition changes. A challenge that arises in all flocculation procedures is how to handle the sludge. The floc settles very slowly, and after it has been centrifuged or drained through filters, it is in the form of a thick cheese-like solid but still contains between 80% and 90% water. The sludge is repeatedly frozen and thawed in an effective procedure. A concentrated salt solution is left behind after the separation of pure ice crystals, and this solution causes the microscopic floc particles to congeal into a form that settles more quickly and is less prone to clog vacuum filters.

9.4.4 Ion exchange For disposal into public water, the effluent following a flocculation procedure can still contain too much activity. It can then be processed by expensive but highly effective ion exchangers. Due to the fact that adsorbing the dissolved salts would quickly deplete their ion exchange capacity, they cannot be employed profitably on solutions with high salt concentrations. In order to eliminate radioactive pollutants, the effluent from a well-managed flocculation process can be run through a cation exchanger or mixed-bed resin after being filtered to remove any remaining floc. Such a resin will remove 99.9% of the majority of radionuclides if

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it is appropriately chosen. Clinoptilolite, greensand and vermiculite are a few minerals that are effective ion exchangers. Although they are far less expensive than synthetic resins, they need longer contact durations for maximum effectiveness.

9.4.5 Glass fixation Primary wastes that are kept in stainless steel tanks that are "self-heating" to extremely high levels are too active to be handled by flocculation or ion exchange. Because liquid storage is rarely viewed as a long-term option, these wastes must be stabilized in a nonleachable solid condition that can be properly kept without risk of leakage or continuous maintenance costs. Putting high trash into a glass is one of the most encouraging solutions. Glass is a material that resists leaching and is easily fabricated. Its composition affects its quality, but it is typically not sensitive to alterations in small components. Due to its low melting point, it may easily be cast in a variety of sizes and shapes for use in various disposal techniques. Glasses are liquid, highly viscous solutions of silicates that have been supercooled. To make soda glass, silica, calcium carbonate and sodium carbonate are melted together. Other variations use potassium, potassium with lead or borate in place of some of the carbonate and sodium, respectively. Coloured glasses are created by using metallic oxides. After the nitric acid is removed and the residue is burned, such a mixture may be ideal for fixing the radioactive metallic oxides that make up the majority of "mixed fission products." Glass fixation is currently carried out on a considerable scale. The leaching of fission products corresponding to the dissolving of 10 10 g of glass per cm2 per day has been carefully studied by analysing the soil and groundwater downstream from the disposal. In 10 years, 1100 Ci has dissolved to less than 1 mCi. This means that for fairly significant amounts of garbage, burying active glass in dry soil or even disposal into a huge body of water would be acceptable. Wastes can be evaporated and then calcined using a variety of techniques. Since oxides are frequently soluble in water, compounds that will combine the oxides to form soluble complexes are typically added. A fluidized bed calciner, a spray calciner or a heated steel container can all be used for the calcination process. In essence, the pot calciner is a disposable steel pipe that has been cooked in an electric furnace. The trash is heated to roughly 900 C and combined with glass-forming fluxes like borax or lead oxide. The waste is sprayed via a nozzle at the top of a heated steel cylinder that serves as the spray calciner. A fine powder that must be stored in a dry area because it can be dissolved by water is created at a temperature of 875 C. Extensive off-gas treatment systems are necessary for all waste fixation procedures including evaporation, sintering and fusing in order to avoid dust and flammable radionuclides contaminating the environment. The gas purification plant is always complicated, complex and expensive, while the concentrating equipment itself is essentially simple and frequently not expensive to manufacture.

9.5 Fracturing of rocks In order to encourage the transportation of oil or gas through a formation and towards a well, the oil industry has devised techniques for making cracks in the rock. The disposal of medium-level wastes has been accommodated by this procedure. Drilled to a depth of

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9.5 Fracturing of rocks

FIGURE 9.2 Various disposal methods of radioactive wastes.

several thousand feet, a horizontally bedded deposit shale has been employed up till now. The well casing is cut through by a high-pressure jet of sand and water that also reaches the bottom of the hole and between the strata. The rock is then divided between the bedding planes by the high-pressure water that is then driven down the well after it has been sealed. The garbage is then added, along with cement, sugar and other chemicals, after the water. After a few hours, the mixture forms a thin horizontal sheet that solidifies. The thickness of the sheet is usually around half an inch (Fig. 9.2). The technique has been used to dispose of a significant amount of garbage. Although the method can be used on a large scale, the equipment, which includes large bins for the cement mix’s ingredients, mixing equipment, a drilling rig and a very powerful pump, is expensive. This is because successive sheets can be injected through the depth of the bedded rock formation at intervals of a few feet.

9.5.1 Salt mines The risk that must be addressed by the majority of radioactive waste management systems is the pollution of public waters that may result in man’s intake of radionuclides either directly or indirectly. Therefore the ideal disposal scenario would be one in which water contact and public access were both impossible. The deep salt mine offers the closest approach to these circumstances. The presence of salt guarantees that water has not been present in the salt bed for millions of years, and geological research can provide assurance that water is not rapidly penetrating into the salt bed. The salt mines’ exhumed galleries are sizable, stable tunnels that can be used for storage and have ample space for risk-free work with moving loads.

9.5.2 Solids The safe handling of the high-volume, low-activity waste is the most difficult issue, just like with liquid wastes. The high activity waste appears to be more harmful at first, yet safe custody is not technically challenging, even though it may be expensive. The majority of low-level waste is made up of “garbage-contaminated clothing, equipment and structural

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material; broken glassware, clean-up materials like cloths and mops; and a significant amount of potentially contaminated” materials like packing and paper that must be handled as active just because it originates in an active area. By burning or baling under intense pressure, a large portion of this material can have its volume decreased. The ash and baled trash must still be dealt with, but the fumes and smoke from incinerators as well as the dusty air from balling factories, are cleaned up using techniques covered under gases. Radioactive material cannot be buried in the ground in some nations due to legal or topographical restrictions. Ground burial is favoured in other places. Bales and noncombustible garbage are likely to be buried in areas with a little population in the latter case. Low-level wastes can be buried without any volume reduction techniques if the land is inexpensive.

9.5.3 Conditioning “Conditioning” refers to the pretreatment of garbage before final disposal. The general goal is to immobilize radionuclides and, if possible, reduce volume. The practices vary greatly from one country to the next. Fixation in bitumen or asphalt is a very efficient conditioning procedure. Bitumen has a low melting temperature and is water-resistant, is highly radiation resistant and has some mechanical flexibility. Bitumen that contains radionuclides or even mixes them with others progressively leaches into the water. When sludges are combined with melted bitumen, the water content is reduced, greatly reducing the volume of the disposals. When it comes to “fixing” otherwise mobile waste radionuclides, bitumen is increasingly preferred over concrete. A liquid discharge’s activity is generally constrained by two factors: 1. The regulating authority establishes absolute discharge limits to guarantee that no member of the public receives a dosage higher than the upper limit set by international recommendations and that the average dose to the population as a whole does not exceed a lower limit. 2. The activity is to be as low as reasonably possible below these limits. It can take extensive research and calculations to determine how radioactivity can get to the most exposed people, or the “critical group”, for example, by concentrating on aquatic species that are subsequently consumed. Identifying what is “In order to make sure that money spent on more complex clean-up methods is justified in terms of the radioactive damage avoided, it might also be essential to pursue a hypothetical economic balance under (2)”. However, the absolute limits (1), which must be met at any cost, are not subject to this type of calculation. Similar to other places, the receiving water body can help dilution to achieve acceptable quantities, but treatment will frequently be required. Concentrating the majority of activity in the smallest volume possible is one of the treatment’s declared goals, and that is frequently the goal of the liquid treatment plant used alone. The ultimate goal is to isolate the activity from the environment because the majority of the environmentally damaging organisms that originate in nuclear effluents are not potentially usable for recovery and recycling, even if it were economically feasible to do so. For radioactive species with considerable half-lives, this isolation from the biosphere necessitates that the activity that is so concentrated be immobilized and then stored in a remote

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9.6 Protection and radiation control

TABLE 9.2 Represents different types of radioactive waste management techniques. Sr. no. 1 2 3 4

Radioactive material 235/238

Uranium (U

90

Strontium ( Sr) 137

Caesium (

Plutonium (

Cs)

239

Pu)

)

Microorganisms

References

Geobacter sulfurrenducens

[14,15]

Micrococcus luteus

[16,17]

Escherichia coli

[18]

Shewanella putrefaciens, G. metallireducens

[19,20]

location, such as an underground repository. It should be emphasized that there are other potential radiation exposure pathways for humans besides the liquid effluent from the plant. The total return to the biosphere, as determined by criteria (1) and (2), must be minimized during all operations, including immobilization, storage, disposal and treatment. This also means minimizing the dose to the operators themselves. A wait time before discharge may be the optimum course of action for an activity with a somewhat short halflife, though this frequently necessitates preconcentration of the activity due to financial considerations (Table 9.2).

9.6 Protection and radiation control Natural sources of radiation are uncontrollable; however, serious efforts can be made to reduce the amount of pollution coming from manmade sources. Therefore quick action must be made to prevent the environment from becoming dangerously over-radiated.

9.6.1 Maximum allowable dose for radiation protection A “tolerance dose” is a dose that a worker can withstand for a long time without experiencing any discernible physical harm. The tolerance dose was determined at 100 Roentgen (R) per year by the International Commission on Radiological Protection (ICRP). In line with ICRP, “The dose that has a negligible chance of causing serious somatic or genetic harm is the one that is considered appropriate for an individual”. Because of the dose, any effects that do occur more frequently are usually mild and won’t be deemed unacceptable by the exposed person or the appropriate medical authorities.

9.6.2 Radiation protection precautions To reduce the impacts of both naturally occurring radiation and artificially induced occupational exposure, radiation prevention methods should have a double-edged strategy. The following precautions should be taken: 1. Airborne explosions of nuclear devices should never occur. These actions should be blown up underground if they are absolutely essential.

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2. To prevent extraneous activation products in nuclear reactors, closed-cycle coolant systems with gaseous coolants of extremely high purification may be employed in it. 3. The use of contaminants is another option for reducing radioactive emissions. Closed cycle systems and tightly sealed boxes can be used to accomplish this. 4. Radioisotope production should be kept to a minimum because once created, there is no way to make them harmless other than with the passage of time. 5. To reduce radio pollutant emissions, a minimum number of nuclear installations should be put into operation. 6. Since human activity cannot go unaffected by the rate of radionuclide decay and subsequent radiation emission, fission reactions should be kept to a minimum. 7. Radio-isotopes can be employed in the nuclear and chemical industries instead of in powder or gaseous form, under a jet of soil or water. 8. Wet drilling and underground drainage may both be used in nuclear mines. 9. The disposal of industrial wastes contaminated with radionuclides should be done with extreme caution. 10. Radiation therapy and nuclear drugs should only be used rarely and when absolutely essential. 11. In workplaces with high radioactive contamination, use high chimneys and ventilation. It appears to be a successful method for distributing radioactive contaminants. 12. The greatest technique to disperse radioactive pollution is through dispersal methods. By using these techniques, the pollutant in a small area is spread out over a vast area, weakening the pollution and minimizing its consequences.

9.6.3 Radiation-based regulation There has always been some environmental influence from human activity. As a result, finding uninhabited areas is fairly challenging. The current efforts to raise living standards and comforts and to fulfill the increasing demand for energy from natural resources will unavoidably have a far longer-term impact on the environment in the years to come. Therefore finding sources other than the traditional ones is urgently needed to reduce radiation dangers. The following actions should be taken to control radiation: 1. Nuclear projects should carefully evaluate a number of factors, including the practice of site selection, its design, building, commissioning, functioning and decommissioning, as well as their short- and long-term impacts. 2. Before choosing and building a major nuclear industry, consideration should be given to environmental aspects such as micrometeorological data, hydrological data, identification of key demographic groups anticipated to be exposed to radioactivity at a higher rate, foundation conditions and the area’s seismicity. 3. The preoperational information that has been gathered should be used to establish the radioactive gas release limitations. The discharge of radio-isotopes from the nuclear power plant should be closely monitored by the monitoring stations. 4. It is necessary to identify the environmental sectors that can safely take radioactive substances.

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5. In order to meet our energy needs and lessen our reliance on current fusion, fissionbased nuclear reactors, every effort must be made to make solar energy and fusion reactors practical.

9.6.4 Limiting workplace radiation exposure Individual contamination is significantly worse in the event of occupational radiation exposure, nuclear waste and radioactive pollution. The following actions could be taken to reduce the risk of external radiation: 1. Operations involving radioactivity can be carried out as long as you maintain a safe distance from the source. 2. Radiation of any kind, including X-rays, is deadly to life. Therefore radiation and the use of X-rays for diagnostic purposes should be done with sufficient care to safeguard the reproductive organs. 3. It is challenging to lower the radiation hazard for individuals working with radioactive materials in the nuclear sector. Therefore the amount of exposure can be reduced by working swiftly and in shifts. 4. When working with radionuclides, shielding can reduce radiation exposure. 5. The ICRP or the country’s board for radioactive waste management should review the primary exposure levels for both the general public and the workplace. The maximum permissible concentration (MPC) limits for certain radioisotopes in air and water have also been established by ICRP. For occupational exposure, the MPC for ingestion and inhalation is 168 hours per week, while 10 of this number is regarded as acceptable for the general population. 6. Despite the difficulty of reducing the risk, radioactive isotope ingestion or inhalation can be avoided with good work practices and sanitary circumstances. These procedures include routine surface inspection and cleaning, cautious hand washing while leaving the experiment room, and no eating or drinking in clean areas. 7. Hoods, boots, caps, gloves and coveralls can all be worn safely to reduce the danger of skin harm and internal contamination. 8. Applying appropriate preventative measures and refraining from allowing radiation pollution to exceed the maximum allowable limits are the best ways to safeguard the body because ingesting long-lived radionuclides might have catastrophic implications. 9. To safeguard living things and their surroundings from the dangers of ionizing radiation, systematic and organized studies should be conducted as part of the scientific advancements made in the field of peaceful applications of nuclear energy.

9.6.5 Security A facility for the storage of radioactive waste needs to be carefully guarded against unauthorized human entry. It needs to be built, run and maintained in a way that prevents the illegal removal of radioactive waste. To prevent unwanted access, a suitable locking mechanism should be offered. It is advised that intruder alarm systems and physical obstacles like fencing be put in place. In the event of an intrusion, security

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measures should guarantee that any unauthorized trash disposal would be quickly found and that effective efforts would be initiated to retrieve the lost material.

9.6.6 Defence against fire It is essential to take precautions to reduce the possibility of an accidental fire while evaluating the overall safety of a radioactive waste storage facility. This risk will be significantly decreased by the careful use of nonflammable building materials while constructing the radioactive waste storage facility. No highly reactive or flammable items should be kept in the radioactive waste storage facility. The use of gas or oil-fired burners for heating is prohibited, and any existing supply pipes for these fuels should be shut off far from the waste storage facility. Packages shouldn’t be exposed to heating in any way. It is vital to communicate with the local firefighting authority. Their opinion should be obtained regarding the placement of firefighting supplies close to the radioactive waste storage facility. Organic scintillation fluids in vials are an example of potentially flammable waste that needs to be stored. These fluids should be adequately packed in heavy-gauge plastic bags and kept in metal drums with covers. The facility should designate a specific location for the storage of these flammable wastes, keeping it physically apart from the other wastes and outfitting it with a top-notch fire detection and suppression system.

9.6.7 Defence against insects and rodents The containment of packed radioactive wastes can be seriously threatened by rats and insects, particularly in facilities for short-term storage where plastic bags may be widely used. Wherever biohazardous radioactive wastes are deposited, protection from insect and rodent infestation is especially important. Both radio1active contamination and potentially pathogenic materials may spread as a result of their intake and dispersal through insect and rodent excretions. A waste storage facility’s insect/rodent management programme should be implemented in coordination with the local health department or another organization with the authority to address these issues, and it must also adhere to all applicable hygienic standards. It is important to accurately identify insect and rodent infestation issues, including their scope. It is necessary to take action to lessen the entry points for rats and insects into the radioactive waste storage facility. Construction materials should be rectified if they have any flaws. A stiff bristle or metallic sealing strip should be used to close any gaps at the bottom of the entrance of the radioactive waste storage facility. If locations for storing food or food waste are found next to a facility for storing radioactive waste, these areas need to be moved since they could serve as breeding grounds for insects and rats. There are commercially accessible poisons that are frequently packaged in prepared trays. These ought to be positioned both within and outside the storage facility for radioactive waste. The presence of radioactivity should be checked in any dead insects or rodents that are discovered. Commercially, a variety of insect and rodent traps are offered. Where insect or rodent populations may have become resistant to chemical techniques of pest management, their use should be taken into consideration. If there is evidence that these visitors are spreading pollution, trapping may be preferable to poisoning.

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9.6.8 Protection from high temperatures Storage of waste should account for any potential temperature extremes that should be avoided. Extreme heat can make biomedical waste putrefy, raising the risk of infectious diseases, the possibility of container rupture and offensive odours. Extreme cold is not as dangerous as extreme heat, but liquid aqueous waste still needs to be protected from frost to prevent aqueous liquid containers from breaking. In a place where temperature extremes are known to happen, like a waste storage facility, temperature management is essential.

9.7 Conclusion Radionuclides utilized in medicine, research and defense have a wide range of properties. Prior to effective waste management, sources must be properly defined in radiological, chemical, biological and physical terms, as well as within their diagnostic, therapeutic and research applications. The waste management programme’s main objective should be the proper management of waste, as well as its avoidance and minimization. For radioactive waste, other nonradiological risks such as physical, infectious and chemical risks must be taken into account in addition to radiological health protection measures. It is necessary to combine the use of universal precautions. A programme for effective waste management must start with the selective collection and separation of garbage at the source. Some Member States might take into account clearance levels obtained by dilution to lower particular activity levels. Before implementing such measures, it is crucial to evaluate the environmental impact. Most radionuclides that are employed in medicine, particularly those that are utilized for diagnostic purposes, have half lifetimes that are normally less than 10 days but can be up to 100 days. Therefore it is important to make full use of onsite decay techniques so that trash can be disposed of at the clearance levels permitted by the applicable regulatory agency based on risk assessment.

References [1] R. Emery, J. Marcus, D. Sprau, Characterization of low-level radioactive waste generated by a large university/hospital complex, Health Phys. 62 (1992) 183 185. [2] K. Kamiya, K. Ozasa, S. Akiba, et al., Long-term effects of radiation exposure on health, Lancet. 386 (9992) (2015) 469 478. [3] C.R. Muirhead, J.A. O’Hagan, R.G. Haylock, et al., Mortality and cancer incidence following occupational radiation exposure:third analysis of the National Registry for Radiation Workers, Br. J. Cancer 100 (1) (2009) 206 212. [4] S.J. Schonfeld, L.Y. Krestinina, S. Epifanova, M.O. Degteva, A.V. Akleyev, D.L. Preston, Solid cancer mortality in the Techa rivercohort (1950 2007), Radiat. Res. 179 (2) (2013) 183 189. [5] Z. Tao, S. Akiba, Y. Zha, et al., Cancer and non-cancer mortality among inhabitants in the high background radiation area of Yangjiang, China (1979 1998), Health Phys. 102 (2) (2012) 173 181. [6] M. Gillies, R. Haylock, The cancer mortality and incidence experience of workers at British Nuclear Fuels plc, 1946 2005, J. Radiol. Prot. 34 (3) (2014) 595 623. [7] R.M. Tuttle, F. Vaisman, M.D. Tronko, Clinical presentation and clinical outcomes in Chernobyl-related paediatric thyroidcancers: what do we know now? What can we expect in the future? Clin. Oncol. (R. Coll. Radiol.) 23 (4) (2011) 268 275.

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[8] UNSCEAR Report to the General Assembly of the United Nations. Annex D. Health Effects Due to Radiation From the Chernobyl Accident. 2008. [9] S. Eapen, S. Singh, V. Throat, C.P. Kaushik, K. Raj, S.F. D’Souza, Phytoremediation of radiostrontium (90Sr) and radiocesium (137Cs) using giant milky weed (Caltotropisgigantea R.Br.) plants, Chemosphere 65 (2006) 2071 2073. [10] H.M. Saleh, Water hyacinth for phytoremediation of radioactive waste simulate contaminated with cesium and cobalt radionuclides, Nucl. Eng. Des. 242 (2012) 425 432. [11] N. Terry, C. Carlson, T.K. Raab, A.M. Zayed, Rates of selenium volatilization among crop species, J. Env. Qual. 21 (1992) 341 344. [12] ErneM, B. Smodis, M. Strok, Uptake of radionuclides by a common reed (Phragmites Australia (Cav.) Trin. exSteud.) grown in the vicinity of the former uranium mine at Zirovskivrh, Nucl. Eng. Des. 241 (2011) 1282 1286. [13] G.E. Boyajian, L.H. Carreira, Phytoremediation: a clean transition from laboratory to marketplace? Nat. Biotechnol. 15 (1997) 127 128. [14] J.D. Istok, J.M. Senko, D.R. Krumholz, D. Watson, M.A. Bogle, A. Peacock, et al., In situ bioreduction of technetium and uranium in a nitrate-contaminated aquifer, Env. Sci. Technol. 38 (2004) 468 475. [15] Y. Suzuki, S.D. Kelly, K.M. Kemner, J.F. Banfield, Direct microbial reduction and subsequent preservation of uranium in natural nearsurface sediment, Appl. Env. Microbiol. 71 (4) (2005) 1790 1797. [16] C.L. Thorpe, J.R. Lloyd, G.T.W. Law, L.T. Burke, S. Shaw, N.D. Bryan, et al., Strontium sorption and precipitation behaviour during bioreduction in nitrate impacted sediments, Chem. Geol. 306/307 (2012) 114. [17] B.D. Faison, C.A. Cancel, S.N. Lewis, H.I. Adler, Binding of dissolved strontiumby Micrococcus luteus, Appl. Env. Microbiol. 56 (1990) 3649. [18] L.E. Macaskie, The application of biotechnology to the treatment of wastes produced from the nuclear fuel cycle: biodegradation and bioaccumulation as a means of treating radionuclide-containing streams, Crit. Rev. Biotechnol. 11 (1991) 41 112. [19] M.P. Neu, G.A. Icopini, H. Boukhalfa, Plutonium speciation affected by environmental bacteria, Radiochim. Acta 93 (2005) 705 706. [20] S.G. John, C.E. Ruggiero, L.E. Hersman, C.S. Tung, M.P. Neu, Siderophore medi a t e d plutonium accumulation by Microbacterium flavescens (JG-9), Env. Sci. Technol. 35 (2001) 2942.

Green Chemistry Approaches to Environmental Sustainability

C H A P T E R

10 Renewable and sustainable energy from CO2 following the green process Shashank Bahri1, Sreedevi Upadhyayula1 and Firdaus Parveen2 1

Heterogeneous Catalysis and Reaction Engineering Laboratory, Department of Chemical Engineering, Indian Institute of Technology Delhi, New Delhi, India 2Department of Chemistry, University of Liverpool, Liverpool, United Kingdom

10.1 Introduction The Fischer
Tropsch (FT) synthesis is a surface polymerization reaction capable of converting coal, biomass and natural gas-derived syngas, typically a mixture of CO and H2, into synthetic fuel range hydrocarbons. FT reaction can produce a wide range of hydrocarbons depending upon the operating conditions and nature of the catalyst. In 1902, Sabatier and Senderens were the first to report hydrogenation reactions to produce methane over nickel catalyst [1]. Syngas conversion to hydrocarbons (mainly oxygenates) over alkali promoted cobalt oxide or osmium at 300 C
400 C, and pressure above 100 bars was first patented by Badische Anilin and Sodafabrik (BASF) [2]. During this time, many efforts were made to transform plentiful coal reserves into liquid fuels and chemicals. The two remarkable discoveries of this era include the direct liquefaction of coal and coal derived-syngas hydrogenation to produce synthetic fuel. Friedrich Bergius was the first to report coal liquefaction via direct hydrogenation of high volatile bituminous coal at 477 C and high pressure up to 700 bars over iron catalyst [3]. In the 1920s, Franz Fischer and Hans Tropsch patented liquid fuel (mainly oxygenates) production from coal gasified syngas over the iron catalyst at 400 C
450 C and 100
150 bars pressure [4]. Later they succeeded in producing hydrocarbons using cobalt and iron catalyst at a milder reaction condition of one bar and 200 C
350 C [5]. FT process was first commercialized in Germany in 1936 and reached a production capacity of 1 million tons per annum in 1940 [6]. During World War II, FT technology marked its great success by supplying fuel to Germany, having no crude reserves of its own. During wartime, the energy insecurity developed an interest in

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the iron-catalysed FT process of producing synthetic fuel. Based on the knowledge acquired from Germany, an FT plant with 0.36 million tons per annum from methanederived syngas was built in Brownsville, Texas, in the 1950s [7]. The syngas feedstock used in this plant was generated from methane reforming. However, soon this plant was ceased due to higher production costs ascribing to the elevated price of methane. Simultaneously, crude oil prices drop due to new vast crude reserves discoveries in Middle East countries. The abundant crude availability slows down the research interest in FT fuel. Meanwhile, the Arab and Israel war in the early 1970s led to an oil embargo mainly imposed over the United States, South Africa, Netherland and Portugal, resulting in an oil shortage. This oil crisis again developed an urge to produce synthetic fuel. Coalto-liquid (CTL) has emerged as an immediate solution to cater increasing oil demands. South Africa expanded its Sasolburg FT plant and installed two additional CTL plants to generate liquid fuel [8]. The combined production capacity of these three plants was 6 million tons per annum. Simultaneous efforts were made in gas-to-liquid technology using natural gas instead of coal for syngas production. The first large-scale GTL plants were installed in Bintulu, Malaysia, by Shell and Mossel Bay, South Africa, by PetroSA. The high profitability of the GTL process ascribing to the increasing crude oil price and abundant availability of natural gas has attracted massive investment from many oil companies (Shell, ExxonMobil, Sasol, Rentech, BP, Syntroleum and ConocoPhillips). OryxGTL (Qatar Petroleum- Sasol) and PearlGTL (Qatar Petroleum- Shell) are the largest GTL plants. Currently, utilization of syngas generated from gasification of waste biomass and agricultural waste in conventional FT synthesis, commonly known as the BTL process, has become a novel route for renewable fuel production. Low operational cost and cleaner emissions are the two advantages of the BTL process. In 1996, the first BTL plant was installed by Choren industries in Freiberg, Germany, with an annual production of 1.5 3 1022 million tons [9]. The production capacity of BTL plants is still smaller than the CTL and GTL technologies. BTL is an emerging technology as biomass is the only available long-term carbon-containing renewable resource. Therefore more significant efforts are required in the field of renewable fuel production using the BTL route.

10.2 Sustainable and renewable energy from CO2 derived renewable biomass A commercial FT has three main sections syngas generation and purification, FT synthesis unit, and product upgradation section (Fig. 10.1). The syngas is a mixture of H2 and CO produced either from gasification or by reforming carbonaceous materials. Syngas production and clean-up is the main section of an FT process, accounting for 60%
70% of the total capital cost of the process [7]. The raw syngas coming from out of gasifiers/ reformers mainly contains H2, CO, CO2 and small amount CH4, nitrogen compounds (NH3, HCN), sulphur compounds (H2S, COS), halides (HCl, HF), argon and carbonyls of Ni and Fe as undesirable impurities. In recent years, significant efforts have been made to reduce contamination levels in raw syngas. The cleaned syngas is H2 deficient and contains a significant amount of CO2, leading to a lower Ribblet ratio (RR , 1). An additional energy-intensive pre-treatment unit is installed before FT reactors to balance the Ribblet ratio of syngas by absorbing excess CO2. The FT synthesis section involves FT reactor, recycles and separating unit for gaseous and

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FIGURE 10.1 Generic representation of a typical Fischer
Tropsch process.

condensed products. Managing heat produced during highly exothermic FT reaction and separating large hydrocarbons with various boiling points are the main challenges of this section. FT synthesis section contributes approximately 20% of the capital costs. The condensed product mixture from the reactor consists of a wide range of hydrocarbons, thus requiring an upgradation section. The upgradation section involves similar technologies of conventional petroleum refining processes and costs 12% of overall capital.

10.2.1 Composition of syngas The composition of syngas depends on the carbon source and the gasification or reforming technology. In a GTL plant, syngas is produced through reforming (steam reforming, dry reforming, partial oxidation or autothermal reforming) natural gas [10]. Reforming natural gas produces syngas with a high H2/CO ratio, but significant CO2 impurity decreases the overall Ribblet ratio (Fig. 10.2). In contrast, CTL and BTL process produces syngas by a thermochemical conversion at 500 C
1200 C in the presence of a gasifying agent (air, O2, steam, CO2). The gasifying agent used has a significant impact on the composition of syngas. Air is a low-cost and abundantly available gasifying agent, but it produces syngas with high N2 concentrations, adversely affecting FT activity. The issue

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FIGURE 10.2

10. Renewable and sustainable energy from CO2 following the green process

Syngas composition from different feedstocks [13].

of N2 dilution can be overcome by using pure O2 as a gasifying agent. However, an additional O2 separation plant requirement increases the production costs [11]. Steam has emerged as a popular gasifying agent because of its ease of availability, economical and ability to improve H2 concentration in syngas [12]. Fig. 10.2 shows that Lurgi gasifiers produce coal-derived syngas with higher hydrogen to carbon monoxide ratios (B2.07). However, the significant concentration of CO2 (B29.7%) in syngas decreases the overall Ribblet ratio (B0.31). Based on the stoichiometry (Ribblet ratio), one mole of H2 is required to effectively convert two moles of CO and three moles of CO2 to produce one unit of hydrocarbon monomer. The composition of syngas mixture is considered as H2 balanced when the Ribblet ratio value reaches unity. However, the cleaned syngas obtained after removing undesirable impurities of CH4, NH3, HCN, H2S, COS, HCl, HF, argon and carbonyls of Ni and Fe from all the routes (reforming and gasification) is either hydrogen lean or contain an excess CO2 concentration. Therefore excess CO2 in the syngas is captured to achieve a desirable H2/CO ratio for FT synthesis. Subsequent sequestration of captured CO2 is essential to mitigate the anthropologic effects of CO2 emissions. Absorption technologies using mono and diethyl amines are the most efficient technology for capturing CO2 from syngas. However, absorption technology’s additional cost and high energy requirement develop a research interest in the direct utilization of syngas with a low Ribblet ratio.

10.2.2 Plausible reaction networks FT synthesis is a complex reaction wherein CO and H2 dissociate on the catalyst surface and form a CH2 monomer. These monomers are subsequently polymerized into a broad

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spectrum of hydrocarbons with C1-C351 carbon numbers. The various intermediate steps involved in FT reactions are as follows: Diffusion of reactants: The reactant molecule diffuses to the catalyst’s external surface from its bulk phase. Reactant adsorption: CO and H2 adsorbed on the active sites. CO 1 T-COT

(10.1)

H2 1 2T-2HT

(10.2)

Chain initiation: The adsorbed reactants dissociate and react to form intermediate species initiating the hydrocarbon chain. COT 1 4HT-CHT2 1 H2 O

(10.3)

Chain propagation: The CH2 monomer reacts further to form long-chain hydrocarbons.
CHT2 n 1 COT 1 4HT-CHT2 1H2 O (10.4) Chain termination and desorption: The growing hydrocarbon chains can either be terminated as paraffin or olefins and desorb from the surface.
To paraffin: CHT2 n 1 2HT-Cn H2n12 (10.5)
(10.6) To olefins: CHT2 n -Cn H2n Secondary hydrogenation: The olefin formed can participate in the secondary reaction to form higher hydrocarbons.
Cn H2n 1H2 - CHT2 n (10.7) Re-adsorption: The olefins formed can be re-adsorbed on the surface and form higher chain hydrocarbons.
Cn H2n - CHT2 n (10.8) The overall FT reaction is written as Eq. (10.9). Water
gas shift (WGS) reaction is an equilibrium-controlled reaction that also takes place on most of the FT active sites. WGS reaction is beneficial for altering the hydrogen to carbon ratio under FT reaction conditions [14]. Direct CO2 hydrogenation is an additional reaction for reaction feed containing H2/ CO/CO2 mixture. Hydrocarbon formation from syngas is a highly exothermic reaction. Therefore FT reactors must be designed to prevent the nonuniform temperature distribution resulting from the large amount of heat generated from the reaction. FT reaction: CO 1 2nH2 -ð
CH22 Þn 1 nH2 O; ΔHo 25 C 5 2 166 kJmol
1 WGS reaction: CO 1 H2 O"CO2 1 H2 ; ΔHo25 C 5 2 41 kJmol
1

(10.9) (10.10)

CO2 hydrogenation: CO2 1 3nH2 -ð
CH22 Þn 12nH2 OΔHo25 C 5
125 kJmol
1

(10.11)

Oxygenates formation: nCO12nH2 1 -Cn H2n11 OH 1 ðn
1ÞH2 O

(10.12)

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10. Renewable and sustainable energy from CO2 following the green process

Boudouard reaction: 2CO-CO2 1 C; ΔHo25 C 5
172 kJmol
1

(10.13)

Oxygenates forming reaction and Boudouard reaction leading to carbon deposition may also occur as the side reactions over FT active sites. According to thermodynamics, the trend of product selectivity follows alkanes . alkene . oxygenates. However, the product selectivity can be tuned by the catalyst design and type of the reactor.

10.2.3 Product distribution during the process It is widely believed that FT product distribution follows the classical Anderson
Schulz
Flory (ASF) model based on the chain-growth probability ascribing to the stepwise addition of -CH2- monomer spices with a high degree of repetition to form long-chain hydrocarbons [15]. The chain growth probability (α) can be defined as the ratio of chain growth rate to total turnover rate: αn 5

rp;n rt;n 1rp;n

(10.14)

where n is the carbon number; rp;n is the rate of chain propagation and rt;n is the rate of chain termination. The chain growth probability (α) mainly depends upon reaction conditions (temperature, pressure, feed composition) and the nature of the catalysts. Based on the constant chain growth, the ASF model idealized the product distribution as follows: Mn 5 ð1 2 αÞαðn21Þ   12α ln Mn 5 n ln α 1 ln α

(10.15) (10.16)

where Mn is the mole fraction of the component with n carbon number; α is the chain growth probability and n is the carbon number. Fig. 10.3A shows the theoretical product selectivity as a function of chain growth probability. According to the ASF distribution model, the maximum amount of the C5-C11 range of hydrocarbons is formed when the chain growth probability (α) value lies between 0.7 and 0.85. However, a gradual decrease in the formation of C5-C11 range hydrocarbons was observed over increasing α value beyond 0.9. Thus it is believed that the FT process must maintain higher α values for higher fuel range hydrocarbons selectivity. 10.2.3.1 Deviations from ideal ASF distribution Different precise and predictive product distribution models were explored in the last two decades to elucidate the non-ASF product distribution. The assumption of constant chain growth probability arises discrepancies between ideal ASF distribution and experimental data. Fig. 10.3B illustrates the typical deviations of the ASF plot. In general, the ASF model underestimates CH4 concentration [17]. A positive deviation at C1 hydrocarbon is observed due to the higher CH4 formation rate. Thermodynamic feasibility of CH4 formation than C-C bond formation, secondary hydrogenolysis by demethylation at higher reaction temperature ( . 275 C) and formation of a hot spot in fixed-bed reaction mainly result in higher CH4 formation than

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FIGURE 10.3 (A) Carbon number distribution based on the ideal ASF distribution and (B) Deviations from classical ASF distribution model [16].

predicted by ASF model [18]. The positive deviation at C1 is accompanied by a negative deviation at C2 hydrocarbon. The higher possibilities of C2H4 readsorption on catalyst surface to form higher hydrocarbons results in rapid consumption of C2 hydrocarbon leading to the negative deviation. A similar negative deviation but to a lower extent is also observed in the distribution of C3 hydrocarbon. Further, the secondary reaction involving re-insertion of α-olefins into chain growth leads to a deviation from the ASF model as chain growth probability increases with growing chain length. A double alpha model also interprets the deviation in the distribution of higher chain hydrocarbons based on the superposition of the two independent chain growth probabilities [19]. However, the double
alpha model only predicts total hydrocarbon formation and instability to explain the experimental changes related to an olefin to paraffin ratios. The readsorption of α-olefins and their subsequent participation in secondary reactions affected by vapour
liquid equilibrium or active sites also elucidates the nonASF behaviour. Another explanation is based on chain length-dependent desorption [20]. It is hypothesized that long-chain hydrocarbons have a stronger interaction with catalyst surface and requires higher desorption energy. Therefore chain growth probability and degree of saturation linearly depend on carbon number. The lack of adequacy to describe C1 and C2 hydrocarbon distribution is still an issue in this model. Later, Fortsch et al. proposed an analytical extension of the ideal ASF model with five parameters each linked with the chain growth probability at both low and high carbon numbers, re-adsorption probability of C2 hydrocarbon, enhancement factor of C1 and parameter describing the deviation at higher carbon numbers [15].

10.2.4 Possibilities of using low Ribblet ratio syngas in Fischer-Tropsch reaction The FT process using H2/CO/CO2 syngas involves CO2 in reactants and product streams. Thus it is crucial to understand the influence of CO2 upon FT kinetics. Few

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10. Renewable and sustainable energy from CO2 following the green process

researchers reported CO2 as a nonreactive gas under FT conditions, while others reported a detrimental effect of CO2 upon CO conversion and C51 selectivity attributing to the mild oxidizing effect of CO2 [21
26]. Therefore CO2 removal from syngas is emphasized to improve the FT synthesis kinetics. On the other hand, the addition of CO2 in the syngas is reported to minimize CO2 formation rates. During FT conditions, the oxygen species formed through C-O bond dissociation can be rejected as CO2 or H2O. The presence of CO2 in syngas increases the reverse rates of WGS to attain equilibrium and results in preferential rejection oxygen as H2O [27]. Liu et al. also reported the increased H2O formation rates upon co-feeding CO2 in a syngas mixture [28]. The isotropic study over WGS active catalyst reveals that CO is more involved in hydrocarbons chain growth than CO2 in H2/12CO /13CO2 feed mixture. However, as WGS approaches equilibrium under FT conditions, the interconversion of CO and CO2 becomes much faster than the hydrocarbon formation reaction. Therefore it is evidenced that CO2 can contribute to hydrocarbon formation in two steps [27]. The CO2 is rapidly converted to CO via reverse WGS reaction, followed by CO conversion to hydrocarbons by the conventional FT route. Therefore, the WGS reaction has a significant role in balancing the hydrogen to carbon ratio and determining CO2 formation and utilization. In contrast, 14 CO2 labelled study conducted over a catalyst with low WGS activity does not provide evidence for two-step CO2 consumption as 14CO2 in the syngas mixture has neither CO via reverse WGS nor participated in chain growth to form liquid hydrocarbons [29]. However, traces of radioactive 14C were detected in gas phase hydrocarbons (C1
C4), indicating the possibility of direct CO2 hydrogenation under FT conditions. Henceforth, it may be concluded that syngas composition does not affect product distribution upon employing WGS active catalysts, while selectivity shifts towards the gas phase hydrocarbons over low WGS activity catalyst. Hall et al. incorporated labelled CO2 in syngas during FT synthesis over an iron-based catalyst at 240 C and reported a little conversion of CO2 converted to CO [30]. Krishnamoorthy et al. reported that adding 13CO2 in H2/12CO does not lead to significant isotopic enrichment in hydrocarbon products, indicating that CO2 is much less reactive than CO in chain initiation and growth hydrocarbons [27]. 14C tracer studies have also been indicated the possibilities of a direct methanol formation route from CO2 syngas feedstock [31]. On the other hand, 13CO2 tracer experiments conducted by Badoga et al. found 13C enrichment in CO and C1-C4 lower hydrocarbons and concluded that small concentration CO2 B1.8 vol% in syngas may hydrogenated to hydrocarbons by the reverse WGS reaction [32]. Later, the concept of the critical ratio required for positive CO2 conversion in H2/CO/ CO2 mixture is introduced in the literature. Wang et al. and Yao et al. reported a critical ratio (CO2/CO 1 CO2) of 0.45 and 0.75 for converting a CO2-containing syngas over supported iron catalyst [33,34]. The positive conversion of CO2 signifies the possible utilization of CO2 in hydrocarbon blocks formation, while the negative CO2 conversion indicates the formation of CO2 during the FT process. Therefore syngas with a low Ribblet ratio can directly be fed to the FT reactor by designing an efficient catalyst with intrinsic FTS and WGS activity. High carbon utilization in the FT process will improve efficiency, reduce production costs and enhance industrial sustainability as the enormous amount of CO2 released during syngas generation and from the FT tail-gas is added back to the FT reactor feedstock.

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10.2.5 Enriching the energy value for liquid product Controlling carbon chain growth in a surface polymerized FT reaction is still a research challenge. Typically, 20%
45% (wt.%) of hydrocarbons produced in the conventional FT process has a boiling point above 360 C [35]. The predominant selectivity towards higher molecular weight wax reduces the probability of an FT process. Therefore the complex long-chain hydrocarbons are upgraded to a specific liquid fuel (gasoline, diesel or jet fuel) via various downstream processes. The wax upgradation process consists of similar technologies involved in crude-based petroleum refineries [36]. However, FT syncrude can be refined at much milder conditions (temperature, pressure, H2/feed ratio) than petroleumbased crude oil [37]. 10.2.5.1 Hydrocracking Cracking is an upgradation technique that involves carbon-carbon bond cleavage for converting long-chain-hydrocarbons into middle distillates. Hydrocracking, catalytic cracking and thermal cracking are the main types of cracking reactions. Hydrocracking is catalytic cracking that takes place in the presence of the H2 atmosphere. Fig. 10.4 illustrates the most accepted monomolecular mechanism of linear long-chain hydrocarbons [38]. According to the monomolecular mechanism, n-paraffins are dehydrogenated to form

FIGURE 10.4 Monomolecular and bimolecular mechanisms for hydrocracking saturated hydrocarbons [38]. Reproduced from S. Sartipi, M. Makkee, F. Kapteijn, J. Gascon, Catalysis engineering of bifunctional solids for the one-step synthesis of liquid fuels from syngas: A review, Catal. Sci. Technol. 4 (2014) 893
907. https://doi.org/10.1039/c3cy01021j.

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10. Renewable and sustainable energy from CO2 following the green process

olefins over metallic sites. A carbocation is easily formed once the olefins are adsorbed on the Bronsted acidic sites. Prior to carbon
carbon bond cleavage, carbocation is isomerized to form isocarbocation by secondary carbocation rearrangement through protonated dialkylcyclopropane. The carbon
carbon bond is cleaved from the β-position of a carbocation and forms lighter carbocations. The carbocations are deprotonated and transformed into olefins. At last, these olefins get hydrogenated over the metallic surface to produce lower carbon number saturated hydrocarbons. A balance between acidic and metallic sites in the hydrocracking catalysts is required to minimize the cracking of C11-C20 hydrocarbons and promote isoparaffins’ formation, which improves the cold-flow properties of an FT fuel [39,40]. In another mechanism of hydrocracking (Fig. 10.4), the olefin gets protonated over Bronsted acidic sites and oligomerized with another olefin to form a dimer. The carbocation formed can produce an olefin by returning proton to the acidic sites or cracking to smaller hydrocarbons. The product stream of an FT process contains a large number of α-olefins which may be in-situ protonated over-acidic sites even in the absence of dehydrogenation functionality. Thus, designing an efficient bifunctional catalyst with functionalities for FT synthesis and acidic sites is suitable to decrease the additional energy demands of additional hydrocracking units. However, the hindrance offered by the CO and H2O to hydrocracking components under FT reaction conditions is still a significant challenge for hydrocracking. 10.2.5.2 Other acid-catalysed reactions under Fischer-Tropsch conditions Besides hydrocracking reaction, the acidic sites may also catalyse oligomerization, hydroisomerization, aromatization and alcohol dehydration reactions. An isomerization reaction involves the change in the orientation of a molecule leading to a branched structure, while the molecular formula remains constant [41]. Oligomerization of olefins is another route of increasing carbon number. Oligomerizing ethylene and propylene overacidic sites can produce hydrocarbons with a carbon number up to C13. Both hydroisomerization and oligomerization reactions are also involved in hydrocracking. Therefore the components of hydroisomerization and oligomerization reactions are also involved in the bifunctional catalyst designed for hydrocracking reaction, and the extent of these reactions can be controlled through reaction temperature, acidic strength and the metal to acidic site ratio. The medium strength acidic sites are beneficial to isomerization, while the acidic sites with strong strength are active for hydrocracking reactions [42]. It is reported that alone isomerization activity might decrease the chain-growth probability as the branched hydrocarbons formed do not actively participate in chain propagation compared to the linear hydrocarbons [43]. Meanwhile, the possibility of aromatization is negligible under low-temperature FT conditions [42].

10.3 Catalysts for sustainable conversion of CO2 to energy Iron and cobalt are the two active metals used as commercial FT catalysts [44]. Fe-based catalysts are cost-effective, selective to lower olefins, and operate over a wider temperature range (220 C
360 C). The intrinsic WGS activity of Fe makes it operational for H2-deficient syngas. In FT reaction, iron can exist as oxides (Fe3O4, Fe2O3), metallic state Fe0 and

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195

carbides (χ-Fe5C2; θ-Fe3C; Fe7C3 and ε-Fe2C) depending on reaction conditions [45]. Most studies consider Ha¨gg carbide (χ-Fe5C2) as FT active phase [44
46]. Conversely, χ-Fe5C2 sites promote Boudouard reaction, which often hiders the FT activity and catalyst stability [47]. Owing to such issues, Co has become the preferred choice, even being costlier than Fe. Cobalt-based catalysts provide higher single-pass conversion and selectively produce saturated long-chain hydrocarbons in a milder reaction temperature range (200 C
260 C). They are also more resilient to deactivation than Fe catalysts [48]. However, the negligible WGS activity of Co metal limits their application to syngas with a balanced Ribblet ratio. Many researchers have agreed that Co-based catalysts’ scope could be widened by introducing auxiliary Fe possessing intrinsic WGS activity [49]. Therefore the bimetallic combination of iron and cobalt could escape energy-intense syngas pretreatment for balancing the Ribblet ratio.

10.3.1 Bimetallic catalyst composition Many studies report a significant change in the catalytic performance upon changing the composition of Fe-Co bimetallic catalyst in the FT process [50,51]. The recent Fe-Co bimetallic catalysts used in FT reaction are summarized in Table 10.1. Arai et al. found a superior catalytic performance of Fe-Co/TiO2 than other bimetallic combinations Fe-Ni/ TiO2, Co-Ni/TiO2 and monometallic catalysts (Fe/TiO2, Co/TiO2 and Ni/TiO2) [52]. They also reported a higher selectivity towards the C51 range of hydrocarbons when an equal amount of Fe-Co was supported over TiO2. In another study, adding Fe-2Co/SiO2 catalyst increased the CO consumption rate, and the C2-C4 range of hydrocarbons became the primary product at 260 C [51]. Amelse et al. reported the highest olefins concentration and excellent capability to reincorporate olefins in a growing chain as a synergy arising from alloying 3.41Fe/0.83Co [50]. The enhanced activity of bimetallic catalysts is attributed to the changed electronic interaction between metal species [53]. It was also observed that the addition of Fe enhances Co reducibility, which increases Co-active sites and leads to higher CO conversion. However, the author did not observe any significant effect upon product distribution. Ma et al. reported that adding zirconium (15%) in bimetallic Fe-5Co/SiO2 weaken metal
metal and metal
support interactions resulting in ease of metal reducibility and improved catalytic performance. In contrast, adding potassium (0.05%
5%) led to stronger metal
metal and metal
support interactions, promoting the secondary hydrogenation reactions [54]. The time-on-stream of over 50 hours showed that the iron-rich bimetallic catalyst requires a higher reaction temperature to reach catalytic performance similar to Co rich bimetallic catalyst. Similarly, a higher C2-C4 olefin (B26.1%) and total C4 hydrocarbons selectivity (B16.2%) was reported for 3.71Fe-8.76Co/ZrO2 than a single metal Fe/ZrO2 catalyst [55]. Lin and co-workers reported that the 3.85Fe/1.02Co bimetallic catalyst supported over Y-zeolites exhibits the activity characteristics similarities between 4.94Fe/HY and 3.85Fe-1.02Co/HY in terms of high olefin to paraffin ratio in the lower range of hydrocarbons [56]. Duvenhage and Coville reported the superior performance of bimetallic Fe-Co/TiO2 than monometallic Fe-TiO2 [64]. However, monometallic Co-TiO2 still has better activity than the bimetallic combination. Increasing iron content in a bimetallic system shifts the

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TABLE 10.1 Summary of bimetallic catalyst employed in Fischer
Tropsch synthesis. Author Leal et al. [57]

Ismail et al. [58]

Zhai et al. (2016) [59]

Braganc¸a et al. [60]

Tavasoli et al. [61]

Lo¨gdberg et al. [62]

Catalyst composition 3Fe-7Co/SBA

5.3Fe-5.4Co/CNT

(Fe1Co9)50Al50 (Ternary Alloy)

15Co-13Fe/SBA-15

0.5Co-10Fe/CNT

1.8Fe-10.2Co/γ-Al2O3

Reaction conditions

Conversion (%)



T: 350 C P: 20 bar H2/CO: 2

T: 240 C P: 20 bar H2/CO: 2 SV: 2000h-1

T: 220 C P: 20 bar H2/CO: 2 SV: 1800h-1



T: 220 C P: 20 bar H2/CO: 2



T: 210 C P: 20 bar H2/CO: 1

CH4

52

CO

35

C2
4

7

CO2

n/a

C51

34

CO2

5



T: 350 C P: 1 bar H2/CO: 1 SV: 1900h-1

Selectivity (%)

CH4

34

CO

55

C2
4

51

CO2

n/a

C51

15

CO2

n/a

CH4

17.1

CO

72.5

C2
4

24.1

CO2

n/a

C51

58.8

CO2

5.4

CH4

25.8

CO

3.6

COH

17.4

CO2

n/a

C51

20

CO2

2.4

CH4

9.4

H2

n/a

CO

52

C2
4

3.5

CO2

n/a

C51

85

CO2

2.1

H2

n/a

CH4

9.3

CO

22

C2
4

n/a

CO2

n/a

C51

78.3

CO2

2.9

Remarks High C1 selectivity

High C1 selectivity. Time on stream is only 40 h

High C1 selectivity. Only up to C8 are formed

More selective to oxygenates High C1 selectivity

Oxygenates formation. Unstable time-on-stream after 100 h

Alloying Co with small amounts of Fe improved the activity

Ma et al. [54]

O’Shea et al. [51]

Duvenhage et.al. [63]

Lin et al. [56]

2Fe-10Co- 15Zr/SiO2

Fe-2Co/SiO2

3Co-Fe/TiO2

3.9Fe-1Co/HY

T: 250 C P: 10 bar H2/CO: 1.6

H2

n/a

CH4

15.9

CO

88.3

C2
4

10.5

CO2

n/a

C51

73.6

CO2

2.6

CH4

12



T: 260 C P: 20 bar H2/CO: 1

CO

60

C2
4

30

CO2

n/a

C51

45

CO2

2



T: 220 C P: 10 bar H2/CO: 2 SV: 350h21

T: 220 C P: 10 bar H2/CO: 2 SV: 350h21

CH4

18.4

CO

37

C2
4

13.7

CO2

n/a

C51

67.9

CH4

52

CO

3

C2
4

38.7

CO2

n/a

C51

7.5

Pore volume decrease. Increase carbon deposition

Adding Fe to CO increased CO conv., but C51 select. is still low

CO conv. is low. Low metal surface dispersion

The similar activity of Fe/HY and Fe-Co/HY

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product selectivity towards the lower chain hydrocarbons. Amelse et al. reported a moderate activity of Ni-Fe/SiO2 than the monometallic catalysts [50]. In contrast, a similar catalyst with 10% loading of Ni-Fe on SiO2 resulted in higher C51 selectivity and lowered CH4 formation than the monometallic catalyst [50,52]. These contradicting results develop a consensus that the bimetallic system has a nonlinear relationship between catalytic activity and catalyst compositions. Tavasoli et al. defined 0.5 wt.% of Fe in the CNT supported FeCo bimetallic system as a breakthrough point beyond which the CO conversion value decreases [61]. The cobalt metal increased the chain-growth probability, while iron metal has an intrinsic property of promoting lower olefin formation. In contrast, adding a small amount of Fe in Co-based catalysts does not alter the product distribution. However, a catalyst with a higher Fe: Co ratio produces an excess of CH4 and reduced C51 selectivity. Lodgberg et al. demonstrated that alloying a small to moderate amount of Fe in a Cobased catalyst improved Co/γ-Al2O3 performance under H2-deficient syngas [62]. The higher activity of the Fe-Co catalyst was achieved without increasing WGS activity. On the other hand, alloying a small to moderate amount of Co to Fe-based catalyst resulted in relatively higher WGS activity and lower FT performance than a single metal catalyst. The bimetallic catalyst does not claim any synergy with hydrocarbon selectivity and olefin to paraffin ratio. Also, a more pronounced deactivation was observed in Fe-rich bimetallic combination. Few researchers found co-feeding H2O water beneficial to improve the WGS activity [60,65]. The presence of H2O leads to more pronounced catalyst deactivation. However, these studies are not enough to provide comprehensive information about simultaneous FT and WGS activity over the surface of a bimetallic catalyst. Bragance et al. reported the impact of the Co/Fe ratio and pore distribution of support upon the reducibility of the active metal sites [60]. The higher Co to Fe ratio and the smaller pore size of HMS support resulted in an increased number of FT active sites. However, in this study, the selectivity of CH4 in bimetallic was higher than in monometallic catalysts. The product distribution trend mainly depends on the active phase of the bimetallic catalyst. A small change in the active phase can tremendously affect the catalyst performance. The catalyst preparation route, types of precursor, pretreatment and the nature of support are the significant parameters affecting the active phase of the bimetallic catalyst. Duvenhage and Coville believed that higher metal loading enhances the probability of FeCo alloy formation upon SiO2, TiO2 and Ag2O3 [64]. The monometallic Co/TiO2 either attains face-centred cubic or hexagonal close packing, while pure Fe/TiO2 has a bcc packing. FeCo alloy of bimetallic Fe-Co/TiO2 exhibits the bcc structure for both Fe and Co. However, the face-centred cubic structure of Co is retained at a low Fe to Co ratio. Further to understand the performance of FeCo alloy in FT synthesis, a ternary alloy (Fe1Co9)50Al50 was developed [59]. In order to determine the composition of the active phase and avoid the metal
support interaction effect, bare (Fe1Co9)50Al50 ternary alloy with a specific surface area were loaded on the reactor. The results obtained show that alloys with a Fe/Co ratio of 0.43 could promote C51 selectivity. Moreover, the selectivity of C1 (12%
26%) under all Fe/Co ratios was usually higher than the monometallic catalyst. In general, the literature available on bimetallic FT catalysts is very scanty and does not provide a direct structural activity relationship. The lack of in-depth systematic studies of actual Fe-Co surface composition is leading to contradicting results. Most of these studies reported catalyst performance after a few hours of time-

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199

on-stream ( , 100 hours). Since FT involves a surface reconstruction under FT reaction conditions, a continuous experiment should be performed for more than 100 hours of timeon-stream to gather more insights into surface segregation.

10.3.2 Structural activity relationship A bimetallic Fe-Co catalyst can be synthesized using coprecipitation, solvothermal, dual-impregnation and precipitation deposition methods. Duvenhage et al. compared the performance of Fe-Co bimetallic catalyst with a similar composition prepared from a coprecipitation of nitrate salts and impregnation of metal carbonyl complexes [63]. The FeCo catalyst prepared from dual-impregnation shows better performance than the coprecipitation route. The selectivity trends of these two bimetallic catalysts are entirely different. The dual-impregnated Fe-Co/TiO2 catalyst shows dependency upon the impregnation sequence instead of the concentration of individual metal. In contrast, the coprecipitation catalyst illustrates a correlation with the most abundant metal. Fe and Co may exist in a bimetallic system as individual oxides, spinel structure or in the form of an alloy depending upon the synthesis route. O’Shea et al. reported a physical mixture of Fe3O4 and Co3O4 with no alloy traces, giving higher selectivity (29%) to alcohols [66]. The bimetallic combination is also explored in the dual-bed configuration in which two monometallic catalyst beds are arranged in such a way that the product stream from the first bed directly enters the second catalyst bed. An increase of 19.7% C51 hydrocarbons selectivity with an 11% drop in CH4 selectivity was observed upon stacking Fe on Co in dual bed configuration [67]. Recently, the selectivity towards lighter olefins (C25-C45) in CO2 hydrogenation was boosted upon replacing one Fe cation of Fe3O4 by Co ion in a stoichiometric ratio of ferrite spinel structure (Co11xFe2-xO4) [68]. In continuation, Ismail et al. studied the synergy between Fe and Co ions in colloidally synthesized spinel structured cobalt ferrites (CoFe2O4) nanoparticles targeting lower hydrocarbons (C2-C4) under extreme FT reaction temperatures [58]. The high temperature (HTFT: 350 C) reaction was conducted to target the individual activity of Fe yielding olefins while Co species were activated at low temperature (LTFT: 220 C) for producing long-chain saturated hydrocarbons. The C51 selectivity in LTFT (220 C) is more than double that achieved in HTFT (350 C) conditions. The spent catalyst of LTFT reveals the formation of Fe-Co Janus structured alloy as the dominant phase, while the emergence of carbide phases was seen at the high reaction temperature. Later, Kim et al. also observed the formation of bimetallic alloy carbide (Fe12xCox)5C2 at elevated reaction temperature (340 C) [69]. These alloy carbides have a similar structure with Ha¨gg carbides and are reported as active sites for selective CO2 hydrogenation to lower olefins (C2-C4). Till date, the literature considering the structural activity relationship of bimetallic Fe-Co in FT reaction is limited to lighter olefins (C25
C45).

10.3.3 Deactivation behaviour of Fe-Co bimetallic catalyst Understanding the possible mechanism by which Fe-Co bimetallic catalysts may lose their catalytic activity has a significant role in designing an efficient catalyst. The combination of the relative catalyst cost and improved stability adds competitiveness to the

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technology. The various possible causes of catalyst deactivation in typical FT conditions are as follows: 1. Oxidation of active sites: Water is the main by-product of both FT and WGS reactions. Oxidation of active metal sites by H2O is widely accepted as a cause of catalyst deactivation [70]. It has been reported that the particle size of 4
5 nm does not undergo rapid oxidation under FT reaction conditions [71]. 2. Sintering of active sites: It has been reported in many articles that Co particles may agglomerate during FT conditions and result in activity loss [72]. 3. Deposition of wax: The LTFT process employing Co catalyst produces wax which may hinder the diffusion rate of reactants over the active sites and leads to deactivation [73]. 4. Deposition of amorphous carbon: χ-Fe5C2 phase of Fe formed at higher reaction temperature is responsible for carbon deposition, which causes the permanent deactivation of Fe-Co catalyst [47]. 5. Surface reconstruction: Ascribing to the complex reaction network of FT reaction, the active surface can undergo an intrusive rearrange, leading to a more stable configuration that may decrease overall activity [74]. The literature reporting the deactivation behaviour of Fe-Co bimetallic catalyst in FT reaction is inconsistent. Duvenhage and Coville reported a similar trend of activity loss trend after 50 hours of time-on-stream catalytic run in monometallic and bimetallic catalysts [64]. Few researchers linked the catalyst deactivation with the Fe content of the bimetallic catalyst [75]. According to them, activity loss becomes more noticeable at high conversion upon increasing Fe content in a bimetallic catalyst. In contrast, at lower conversion, Fe-Co bimetallic catalyst attains time-on-stream stability. The formation of a χ-Fe5C2 phase of Fe at a higher reaction temperature is the main reason for the permanent deactivation of the Fe-Co catalyst. Lodgberg et al. reported that the bimetallic Fe-Co combination is more stable than that single metal catalyst [62]. However, the H2O formed at higher CO conversion leads to rapid deactivation of the Fe-Co catalyst.

10.3.4 Catalyst for low Ribblet ratio syngas The syngas lower Ribblet ratio ( , 1) value signifies the H2 deficiency and high CO2 contamination. Currently, direct utilization of low Ribblet syngas as a feedstock has become an aspect of consideration. High carbon utilization in the FT process will improve its efficiency, reduce production costs and enhance industrial sustainability as the enormous amount of CO2 released during syngas generation and from the FT tail gas is added back to the FT reactor feedstock summarized in Table 10.2. The consumption of CO2 in the low Ribblet ratio syngas is still debatable. Visconti et al. proposed that CO2 behaves as inert in the presence of CO, responsible for the slower adsorption of CO2 than CO over coactive sites [21]. Gnanamani et al. also reported the similar inert behaviour of CO2 over a Co-based catalyst at a higher partial pressure of CO [22]. Further, a more pronounced deactivation of Co/γ-Al2O3 catalyst was reported upon co-feeding CO2 in syngas mixture [24]. The mild oxidizing effect of CO2 was speculated as the cause of deactivation in Cobased catalysts. Later, Yali et al. reported that hydrogenation of CO2 along with CO over

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TABLE 10.2 Author Sonal et al. [78]

Lu et al. [79]

Rafati et al. [80]

Li et.al. [81]

Yan et al. [82]

Dı´az et al. [77]

Summary of catalyst employed in Fischer
Tropsch synthesis using low Ribblet ratio syngas.

Catalyst Fe-2Co/SiO2

Carbon-encapsulate iron carbide /iron nanoparticles

FeCuKSiAl

Co-0.4%Mn/SiO2

Pd-Fe/HZSM-5

Co/CNF

Yan et al. [83]

K-Fe-Co-Mo/γ-Al2O3

Yan et al. [84]

Carbon encapsulate Fe

Gnanamani et.al. [22]

Yao et al. [34]

Yao et al. [76]

Co-Pt/γ-Al2O3

Fe/TiO2

Co/TiO2

Reaction conditions and syngas composition 

T: 240 C P: 20 bar RR: 0.5 CR: 0.35 

T: 310 C P: 69 bar RR: 0.23 CR: 0.36 

T: 300 C P: 20 bar RR: 0.5 CR: 0.74 

T: 240 C P: 20 bar RR: 0.41 CR: 0.13 

T: 310 C P: 86.2 bar RR: 0.23 CR: 0.36

T: 250 C P: 20 bar RR: 0.68 CR: 0.28

T: 250 C P: 69 bar RR: 0.24 CR: 0.36 T: 250 C P: 67 bar RR: 0.24 CR: 0.38

T: 220 CP: 20 bar RR: 0.87 CR: 0.30 

T: 259 C P: 20 bar RR: 0.97 CR: 0.63 

T: 200 C P: 20 bar RR: 1 CR: 0.64

RR, Ribblet ratio 5 H2/(2CO 1 3CO2); CR, critical ratio 5 CO2/(CO 1 CO2).

Conversion Selectivity (%) (%) H2

n/a

CH4

CO

82

C2
4 34

18

CO2
40.2 C51

48

H2

85.5

CH4

8.3

CO

88

C2
4 25.8

CO2 12

C51

65.9 7.6

H2

n/a

CH4

CO

89.6

C2
4 20.5

CO2 25.2

C51

71.9 8.1

H2

76.1

CH4

CO

47.8

C2
4 5.8

CO2 11.9

C51

86.1

H2

n/a

CH4

17.4

CO

75.7

C2
4 22.3

CO2 n/a

C51 CO2

38.9 21.4

H2

67.1

CH4

56.1

CO

64.1

C2
4 1.7

CO2 n/a

C51 CO2

37.9 4.3

H2

n/a

CH4

6.9

CO

53.4

C2
4 26.3

CO2 13.7

C51

66.8

H2

n/a

CH4

5.7

CO

85.2

C2
4 12.9

CO2 n/a

C51 CO2

71.3 10.1 13.7

H2

61.3

CH4

CO

81.6

C2
4 9.1

CO2 0

C51

77.2 23.3

H2

n/a

CH4

CO

70.5

C2
4 72.7

CO2
0.3

C51

n/a 49.8

H2

n/a

CH4

CO

82.6

C2
4 50.2

CO2 8.4

C51

n/a

Remarks Negative CO2 conv. High C1 selectivity

Pressure too high Thermal instability (30% loss)

No time on stream data is provided

Deactivates after 72 h

CO2 is product Pressure too high High C1 selectivity

CO2 is product. High C1 selectivity Deactivates after 48 h

Pressure too high

CO2 forms Selectivity is CO2 free basis

CO2 behaves as inert Platinum promoter is costly

Selective towards lower hydrocarbons CO2 conv. negative

Selectivity towards C1 is very high Balanced hydrogen condition

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Co-based catalyst follows a typical ASF product distribution providing the critical ratio (CO2/(CO 1 CO2)) was higher than 50% [76]. The carbon nanofibre supported cobalt catalyst was also tested for syngas with a Ribblet ratio of 0.68 [77]. The co-feeding of CO2 leads to a lower CO conversion and shifts selectivity to lower chain hydrocarbons. However, CO2 addition was found to increase the selectivity towards undesirable CH4. Unlike monometallic Co-based catalysts, Fe catalysts can convert CO2 to hydrocarbons via reverse WGS reaction. In the case of bimetallic FeMn catalyst, CO2 in feed increased the reverse rate of WGS reaction leading to decreased hydrogen surface concentration and producing more H2O, which promotes olefin formation [28]. Further, Li et al. reported the influence of adding Mn promoter in Co/SiO2 catalyst [81]. With the addition of 0.4 Mn, a CO and CO2 conversion of 47.8% and 11.9%, along with a C51 hydrocarbon selectivity of 86.1% under syngas of 0.41 Ribblet ratio was achieved. The addition of Mn promoter increases the surface dispersion of Co and also weakens the metal-support interaction leading to ease of Co reducibility. However, Mn addition does not show any synergistic effect upon time-on-stream. A steady decrease in activity was observed beyond the continuous 12 hours of the catalytic run. Therefore more emphasis is given to a bimetallic system comprising activity for both FT and WGS reactions. Yali and co-workers speculated that the equilibrium constant determines whether CO is converted to CO2 or CO2 to CO based on the thermodynamic calculations and its experimental validation over Fe catalyst under LTFT conditions [34]. Yan et al. demonstrated a continuous process involving syngas with a low Ribblet ratio (B0.24) produced from gasification of Oak-tree wood chips to produce synthetic turbine aviation fuel [83]. A positive CO2 (B13.7%) and CO (B53.4%) conversion with 66.8% C51 hydrocarbons were achieved over a multifunctional K-Fe-Co-Mo/γ-Al2O3 catalyst. However, the requirement of 69 bars reaction pressure is the limitation of the process. Rafati et al. developed a similar FeCuKSiAl catalyst and reported 89.6% CO and 25.2% CO2 conversion at a much lower reactor pressure of 20 bars using syngas with a 0.5 Ribblet ratio [80]. The author claims that balancing the Ribblet ratio could increase the CH4 selectivity at the expense of liquid hydrocarbons formation. However, long-duration time-on-stream stability runs were missing in the article. In another study, Yan et al. used the waste biochar to synthesize carbon encapsulated iron nanoparticles and demonstrated catalyst time-on-stream stability of more than 1500 hours at 310 C and 67 bar reactor pressure [84]. CO2 formation instead of consumption in the entire reaction temperature range (250 C
350 C) is the major drawback of the catalyst design. In continuation, Lu et al. modified carbon encapsulated iron catalyst to carbon encapsulated iron carbides/iron nanoparticles (CEICINs) consisting α-Fe, θ-Fe3C and Fe15.1C [79]. The CEICINs core-shell nanostructure catalyst achieved CO (B88%) and CO2 (B12%) conversion with 65.9% selectivity towards C51 range of hydrocarbons using a syngas with 0.23 Ribblet ratio at 310 C reaction temperature and 69 bar reactor pressure. However, a 30% weight loss observed in the thermogravimetric indicates the thermal instability of the iron impregnated carbon black. Further, Pd promoted Fe/HZSM-5 catalyst was developed to produce aromatic-rich gasoline from syngas with a 0.23 Ribblet ratio [82]. The Pd added as a promoter enhanced the production of aromatic hydrocarbons. The higher reaction temperature facilitates higher aromatic selectivity (29%
45%) at the expense of high CH4 and CO2 selectivity. Henceforth, high CH4 selectivity, lower CO conversion, instability in

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203

longer time-on-stream, CO2 consumption and formation pathways and lower chaingrowth are still the major issues involved in utilizing syngas with low Ribblet ratio in the conventional FT process.

10.4 Reaction mechanics and kinetics 10.4.1 Fischer-Tropsch mechanism The reaction mechanism of FT synthesis is a matter of extensive research for more than 90 years ascribing to the complex CO adsorption and the involvement of a broad spectrum of products. The FT reaction can generally be divided into five elementary steps involving adsorption of CO and H2, chain initiation, chain propagation, chain termination and desorption of hydrocarbons. CO adsorption is the first and most crucial step for initiating FT reaction wherein CO and H2 adsorb, dissociate and react to form a CH2 monomer. The CO adsorption could be associative or dissociative, and CO can be dissociated with and without the assistance of H2. The state of hydrogen during a reaction is still a matter of research. It may be in the gaseous phase or adsorbed state on the catalyst surface. Therefore, a molecular scale understanding of the surface chemistry of CO consumption pathways is required to improve the existing catalyst design. A detailed description of the four most prominent monomer formation and chain-growth pathways is discussed in this section. 10.4.1.1 Alkyl mechanism The alkyl mechanism is the oldest and widely used mechanism. Fischer and Tropsch first proposed it, and since then, it has undergone various revisions [5]. This mechanism is also known as carbide, carbine or CHx insertion mechanism. Fig. 10.5 shows the alkyl mechanism. In this mechanism, CO adsorbed over active sites could dissociate with and without H2 assistance to form surface carbides. The oxygen atom of CO can either be rejected as CO2 or H2O. The surface carbides are then hydrogenated to form CH2. These CH2 intermediate spices are the monomer unit of the FT hydrocarbons. Further, CH2 is hydrogenated to form chain initiators CH3 species and chain-growth propagates by successive addition of CHx alkyl species. Finally, these growing chains are terminated by hydrogenation, dehydrogenation or hydroxylate to form n-paraffin, olefin and alcohol, respectively. The alkyl mechanism is a continuation of the carbide mechanism. Brady and Pettit provided experimental evidence of the presence of intermediates involved in an alkyl mechanism and confirmed that CH2 acts as a monomer during the chain growth of hydrocarbons [85]. The termination of the growing chain in the alkyl mechanism mainly produces n-paraffin and α-olefins. The inability to explain branched alkanes and oxygenate formation in FT are the main weakness of the alkyl mechanism. Initially, re-insertion of olefins is believed to be pathway of branched alkanes formation. However, the experimental results illustrate that the amount of branched alkanes is higher than the expected for olefin reinsertion route [85]. On the other hand, Johnston and Joyner hypothesized that hydroxyl groups could be responsible for oxygenate formation [86]. However, the experimental validation of the involvement of the surface hydroxyl group in alcohol formation is still not available in the literature.

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FIGURE 10.5

10. Renewable and sustainable energy from CO2 following the green process

Schematics of the alkyl mechanism.

10.4.1.2 Alkenyl mechanism Maitlis et al. proposed an alkenyl mechanism for α-olefin prediction in the FT process [87
89]. According to this mechanism, methylidyne (CH) and methylene (CH2) react and form vinyl spices (CH 5 CH2). These vinyl groups formed are considered as chain initiators of the FT product (Fig. 10.6). In the alkenyl mechanism, the hydrocarbon chain grows via successive addition of methylene (CH2) to surface vinyl spices (CH 5 CH2) and leads to surface allyl species (-CH2CH 5 CH2R) formation. The further reaction proceeds with the allyl-vinyl isomerization and forms alkenyl species (CH 5 CHCH2R). The growing chains are terminated via hydrogenation of alkenyl species (CH 5 CHCH2R), and finally, α-olefins (CH2 5 CHCH2R) is desorbed from the catalyst surface. The alkenyl reaction mechanism fails to explain the formation of n-paraffins for which additional pathways is required. 10.4.1.3 Enol mechanism Storch et al. derived alternative pathways of FT product formation wherein oxygencontaining enol species are involved in the mechanism [90]. In this mechanism, enol species (-CHO) are formed through the hydrogenation of adsorbed CO. The chain propagates through the condensation reaction between CHOH and RCOH species, and H2O is eliminated. The growing chain termination and product desorption yields oxygenate (alcohols and aldehydes) and α-olefins as a product. In this mechanism, n-paraffin formation is considered the secondary reaction of α-olefins, and the primary formation of n-paraffins requires an additional reaction pathway.

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FIGURE 10.6 Schematics of alkenyl mechanism.

10.4.1.4 CO insertion mechanism Pichler and Schulz developed a reaction mechanism in which adsorbed CO acts as a monomer, and the intermediate surface methyl groups act as a chain initiator [91]. The chain growth propagates with the adsorbed CO insertion into the metal alkyl bond and forms surface acyl intermediate species (C-OR). The oxygen atom of acyl species is rejected in H2O, and intermediate alkyl species are formed (Fig. 10.7). Similar to the alkyl mechanism, the CO insertion mechanism also terminated through hydrogenation reaction for nparaffins ad dehydrogenation to form α-olefins. The predictability of oxygenates in the FT product distribution is the main advantage of this mechanism. Many researchers consider the “CO-insertion” mechanism as a significant route leading to oxygenation formation under FT reaction conditions [92,93].

10.4.2 Fischer-Tropsch kinetics From the perspective of chemical engineering, understanding reaction kinetics is a prerequisite for developing a mathematical model for reactor design and scaling-up technology to a commercial level. The kinetic expressions and estimated thermokinetic parameters provide quantitative information such as reactant disappearance rates and product formation rates, essential for achieving optimal performance in a process. 10.4.2.1 CO activation in Fischer-Tropsch active sites The FT kinetics is mainly divided into three categories. The first category focuses only upon the consumption rate of H2 and CO, while the second category targets the formation rate of the hydrocarbon products. The third category provides the comprehensive model comprising both the reactants consumption rate and product formation rate. In all three

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FIGURE 10.7

10. Renewable and sustainable energy from CO2 following the green process

Schematics of CO insertion mechanism.

categories, empirical power law, semi-empirical and mechanistic approaches can be applied to derive the rate expression. The mechanistic models are developed considering the sequential pathways with an assumption of a rate-controlling step. The rate of CO consumption is found dependent upon CO adsorption, dissociation and monomer formation. Anderson et al. proposed the earliest and simplest model to predict the FT reaction over Fe-based catalyst by assuming first-order linear dependency upon H2 partial pressure [94]. The applicability is limited to 60% syngas (CO 1 H2) conversion and high WGS activity. Later, Anderson proposed an empirical model with an inhibition effect of water. Huff and Satterfield derived a similar rate expression based on the LHHW approach [95]. Van Der Laan and Benackers derived several rate expressions based on the different reaction mechanisms using the LHHW approach and postulated that similar rate expressions could be derived from entirely different reaction mechanisms [96]. Among several mechanisms, the combined enol/carbide mechanism shows high goodness of fit of the experimental data. The overall FT activation energy for iron-based catalysts lies between 50 and 105 kJmol21 [17]. The majority of the FT kinetics experiments were reported over Fe-based catalyst, while only a few rate expressions were developed over Co-based catalysts. Zennaro et al. proposed an empirical rate expression for FT reaction rate considering promoting H2 and inhibiting effect of CO over Co-based catalysts [97]. LHHW and ER approaches were also explored in the derivation of rate expressions over Co-based catalysts. Outili et al. proposed a rate expression based on the carbide mechanism and CH2 formation as the rate-limiting step, overactive sites of the cobalt catalysts [98]. In continuation, Wojciechowski et al. proposed rate expression based on the carbide and enol/carbide mechanism considering hydrogenation of intermediate formyl to form carbon and water as the rate-determining step [99]. Later, Yates and Satterfield coined CO as the most abundant species on the catalyst surface [100]. Thus the CO inhibition

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10.4 Reaction mechanics and kinetics

term must be included in the denominator of the rate expression. Other models reported over cobalt catalysts include unassisted and H2 assisted CO dissociation [17,101]. Most experimental data reported that bimetallic catalysts fit kinetic behaviour based on the enol/carbide mechanism [102
104]. Ojeda et al. reported the formation of CH2T monomer from the dissociation of intermediate formyl species (HCOT) as a favourable route for the hydrocarbon chain initiation step due to its lower energy barrier (106 kJmol21) as compared to unassisted CO dissociation having a higher energy barrier of 367 kJmol21 [105]. The intermediate hydroxycarbene (HCHOT) condensation is also reported as a possible rate-determining step for CH2 monomer formation [106
108]. A summary of various rate expressions is summarized in Table 10.3. TABLE 10.3 catalysts.

Literature rate expressions and activation energy in FT reaction over bimetallic/ trimetallic Activation energy (kJmol21)

Reference

Catalyst/ reactor

RDS/rate expression

Reaction conditions

Ni-Co/ HMS Fixed-bed reactor

COT 1 HT"HCOT 1 T

T 5 533
573K P 5 1
5 bar SV 5 3600 h21 H2/CO 5 2

64.21

[103]

T 5 523
553 K P 5 1
12 bar SV 5 3600 h21 H2/CO 5 1
2

82.22

[102]

rFT 5 Fe-Ni-Co/ MgO Fixed-bed reactor

kp ðbCO PCO Þ0:5 ðbH2 PH2 Þ0:5 ð1 1 bCO PCO 1 ðbH2 PH2 Þ0:5 Þ2

COT 1 HT"HCOT 1 T rFT 5

kp bCO PCO ðbH2 PH2 Þ

ð1 1 bCO PCO 1 ðbH2 PH2 Þ0:5 Þ2

Fe-Ni/ Al2O3 Fixed-bed reactor

CHT 1 HT"CH2 T

Co-Ru/SBA 3D printed microchannel microreactor

COT 1 HT"C1H2 O 1 2T

Fe-Ni-Ce Fixed bed microreactor Co-Mn/ TiO2 Fixed bed reactor

Co-Ni/ Al2O3 Fixed bed reactor

0:5

APCO ðPH2 Þ0:5 rFT 5 ð11kCO PCO 1bH2O PH2O Þ2

rFT 5

kK1 PCO K2 PH2 ð11K1 PCO 1K2 PH2 Þ2

COT 1 OT 1 4HT"C1H2 O 1 2T kp bCO PCO ðbH2 PH2 Þ

2

rFT 5

ð1 1 2ðbCO PCO Þ0:5 1 ðbH2 PH2 Þ0:5 Þ6

COT 1 H2 "HCOHT kp bCO PCO PH2 rFT 5 1 1 bCO PCO COT 1 HT"HCOT 1 T rFT 5

APCO PH2 2 ð11bCO P0:5 H2 PCO Þ

T 5 493
533K 103.82 P 5 1
12 bar SV 5 2100
7000cm3h21g21 H2/CO 5 1.5
2

[109]

T 5 483
543K P 5 1 bar SV 5 3.15
25.2 kgcathkmol21 H2/CO 5 2

32.21

[110]

T 5 503
523K P 5 2
10 bar SV 5 3000 h21 H2/CO 5 2

60.4

[111]

T 5 463
553K P 5 1
10 bar SV 5 2700 h21 H2/CO 5 1
3

35.13

[106]

T 5 503
543K P 5 2
12 bar SV 5 2000h21 H2/CO 5 1
3

78.7

[108]

(Continued)

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TABLE 10.3 (Continued) Activation energy (kJmol21)

Reference

T 5 493
513K P 5 5
15 bar H2/CO 5 1.5
3.5

93
95

[100]

T 5 553
653K P 5 1
12 bar SV 5 2000 h21 H2/CO 5 1
2.1

40

[104]

T 5 473
553K P 5 10
30 bar SV 5 1800
6600 mLh21g21 H2/CO 5 1
2.1

82.34

[112]

T 5 543
603K P 5 17 bar SV 5 10.4 NLh21g21 H2/CO 5 1
2.1

104

[113]

20:05 rFT 5 aP0:6 H2 PCO

T 5 473
553K P 5 10 bar SV 5 400
700 h21 H2/CO 5 1
3

92

[114]

COT 1 H2 "HCOHT

T 5 523
543K P 5 1
7 bar SV 5 6000 h21 H2/CO 5 1
2.5

82.4

[115]

T 5 473
553K P 5 10 bar SV 5 400
700 h21 H2/CO 5 1
3

85.18

[116]

Catalyst/ reactor

RDS/rate expression

Co-MgO/ SiO2 Slurry

rFT 5

FeMn-K/ Al2O3 Fixed bed

Fe-Co-Ni Fixed bed

Fe-Co-Mn Fixed bed

ð11bCO PCO Þ2

kPCO P0:5 H2 ð11aPH2 1bCO PCO Þ2

COT 1 H2 "HCOHT rFT 5

Fe-K/Al2O3 Berty fixed bed

APCO P0:5 H2

COT 1 HT"HCOT 1 T rFT 5

Fe-Cu/SiO2 Spinning basket

APCO PH2 1 1 bCO PCO

COT 1 HT"HCOT 1 T rFT 5

Fe-Co /SiO2 Fixed bed

Reaction conditions

aPCO bPH2 ðbCO PCO 1cPH2O Þ2

kaPCO bPH2 rFT 5 ð11bCO PCO 1bH2 PH2 Þ2 CT 1 OT 1 4HT"CH2 T 1 H2 O 1 T rFT 5

kaPCO ðbH2 PH2 Þ ð112ðbCO PCO Þ0:5 1ðbH2 PH2 Þ0:5 Þ6 2

The intermediate HCHOT species can either react with molecular H2 or with surface adsorbed atomic H. Moreover, most of the available literature only investigates the kinetics mechanism of the FT reactions or the WGS reaction model. A comprehensive model (RFT 5 -RCO-RWGS) describing the simultaneous CO consumption in FT and WGS reactions under a complex FT synthesis reaction network is still missing in the literature. 10.4.2.2 Inhibition effect of H2O and CO2 Anderson et al. postulated that the FT reaction rate is proportional to the partial pressure of H2 up to the 60% CO conversion [117]. The discrepancies arising at the higher conversion are attributed to the catalyst oxidation effect of higher partial pressure of H2O or CO2. Thus the FT reaction rate is proportional to the fraction of the reduced iron determined from the catalyst reduction by CO or its oxidation by H2O. Based on this

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hypothesis, a rate expression was developed considering first-order kinetics in hydrogen with the weighted CO and H2O ratio [117]. The variation of estimated parameters along with syngas composition at constant temperature was the major drawback of this model. WGS reaction can alter the FT reaction rate by changing the concentration of reactants and products. Therefore several models were developed considering the H2O and CO2 partial pressure terms [118
120]. In general, the inhibition effect of H2O is much stronger than CO2 inhibition ascribing to the significant difference in adsorption coefficients [118]. According to LHHW rate expression, the more potent inhibition of H2O is rationalized by the competitive adsorption effect between H2O and CO [121]. Ledakowicz et al. introduced a CO2 inhibition term to describe the rate data in which almost all H2O formed by the FT is converted to CO2 due to the high WGS activity [122]. The applicability of this molecular hydrogen model was extended to a low H2/COB0.8 ratio syngas composition where H2O concentration is negligible [122]. In continuation, Yates et al. conducted experiments by co-feeding CO2 in the syngas mixture with H2/COB 0.67
0.72 and reported that the inhibition ascribed to CO2 was caused by the H2O produced by the reverse WGS reaction [123]. Botes et al. proposed a dual-site rate expression including CO, H2O and vacant sites squared terms in the denominator and evaluated the goodness of fit of the various literature reported data over iron catalyst [124]. However, the effect of H2O inhibition was found statistically insignificant. Later, Zhou et al. proposed CO2 and H2O terms as a vacant site term instead of inhibiting term and considered CO concentration and vacant site as an essential deriving parameter of FT kinetics over Fe catalyst [125]. In contrast, most of the cobalt catalysed FT reactions with low WGS activity consider CO consumption as a function of the partial pressure of CO and H2. Wojciechowski et al. concluded the rate of FT reaction equivalent to the rate of CO consumption ascribing to the low WGS activity of Co-based catalyst [99]. However, cobalt-manganese oxide exhibits typical kinetics of iron-based catalyst with a considerable WGS activity showing the firstorder dependency to account for CO2 formation [126]. Das et al. studied the effect of cofeeding water on Co/Al2O3 catalyst [127]. No significant effect of water addition up to 25% (vol %). However, an increase in H2O concentration beyond 20% negatively affects the FT kinetics. A semiempirical model with the H2O inhibition term fits well with the negative reversible effect of H2O. Recenlty, Ma et al. postulated that the inhibition effect acts differently at high ( . 70%) and low ( , 70%) CO conversions over Fe-based catalyst [128]. Based on the fitting of 83 set of experimental data set, H2O inhibition effect was found insignificant while CO2 inhibits only at the higher CO conversion. 10.4.2.3 CO activation in WGS active sites It is widely believed that the CO2 of the H2/CO/CO2 mixture is converted to hydrocarbons in two steps [129]. Firstly, CO2 is reduced to CO through reverse WGS reaction. Subsequently, the CO produced is transformed to hydrocarbons via the FT reaction. Meanwhile, few researchers report possible direct hydrogenation of CO2 as an additional reaction [130]. Henceforth, developing a comprehensive kinetic model that can describe the combination of both FT and WGS reactions is imperative for understanding the reaction mechanism. The oxygen atom during cleavage of the C-O bond can be transformed into H2O or CO2 under FT reaction conditions. The H-assisted CO activation involves hydroxyls (OHT) formation through dissociation of HxCO intermediate species, which preferentially reacts

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10. Renewable and sustainable energy from CO2 following the green process

with chemisorbed HT and rejects O-atom as H2O. In Fe catalysed reactions, co-occurrence of unassisted CO dissociation and H-assisted pathway of CO activation are responsible for rejecting O atom as CO2 [105]. Ledakowicz et al. adopted an enol mechanism over Fe catalyst considering the inhibition effect of CO2 and H2O and developed a syngas disappearCO PH2 ance rate expression rsyngas 5 ð1 1 1 KkP [122]. Later, experimental and theoretical 1 PH2O 1 K2 PCO2 Þ studies indexed the negligible inhibition of H2O on the reaction, while CO2 inhibition only happens at high CO conversion ( . 65%) [122]. Using CO2 containing syngas mixture as feedstock will shift WGS equilibrium in the reverse direction, resulting in enhanced CO2 conversion to CO and subsequent CO conversion to hydrocarbons. Therefore understanding the WGS mechanism coinciding with FT reaction is significant, mainly when syngas with a low Ribblet ratio is used as a feedstock. Regenerative redox and formate mechanisms or empirical equations are commonly used for developing WGS rate expression [96,122]. In-situ infrared analysis in DRIFTS mode evidenced the feasibility of intermediate HCOOT species formation over transitional metals resulting in a better fit of experimental data in formate-based mechanisms than the direct redox mechanism [131,132]. The adsorption of CO2 and H2 is assumed relatively negligible than CO and H2O over WGS active sites. Gerard P. van der Lan et al. proposed a rate expression based on the formate mechanism by considering a reaction between an associative water molecule and adsorbed carbon monoxide to form intermediate formate species as a rate-determining step (COT 1 H2O" HCOOT 1 HT) [96]. In another model, rate expression was developed by assuming the reaction between adsorbed carbon monoxide and hydroxyl group produced by H2O dissociation (COT 1 OHT" HCOOT 1 T) as a rate-determining step. The discrimination between associative (H2O) water and dissociative hydroxyl (OHT) form of water has no significance when CO2 formation through formate dissociation is considered the slowest step. Later, Ma et al. reported a generalized empirical rate expression for WGS reaction with CO2 inhibition [128]. This empirical rate expression lumping the adsorption/desorption of H2 and CO2 results in an improved data fitting due to the insignificant order of PH2 at low CO conversion. Till date majority of the reported studies only investigated the kinetics of either FT or WGS reaction, leading to a scarcity of a comprehensive model capable of elucidating simultaneous dual-site consumption of CO molecule in FT and WGS reaction over a bifunctional catalyst.

10.5 Conclusion Although a lot of research has been done on FT synthesis using Fe-Co bimetallic catalyst, there is still limited literature on the activity and stability of low-cost bimetallic FT catalyst supported on hierarchical porous zeolites for diesel fuel synthesis from FT reaction, especially when the feed syngas has a low Ribblet ratio. The detailed study is required on FT reaction using hierarchical zeolite supported catalysts for higher carbon number fuels using low Ribblet ratio feed syngas and their structure activity relationship. Achieving catalyst stability with negligible deactivation during a long time-on-stream and minimizing the methane formation is still a challenge.

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References

211

References [1] P. Sabatier, J.B. Senderens, Hydrogenation of CO over nickel to produce methane, J. Soc. Chim. Ind. 21 (1902) 504
506. [2] R.G. Herman, Classical and non-classical routes for alcohol synthesis, Stud. Surf. Sci. Catal. 64 (1991) 265
349. [3] A.N. Stranges, Friedrich Bergius and the rise of the German Synthetic Fuel Industry, Chic. J. 75 (1984) 643
667. [4] F. Fischer, H. Tropsch, About the production of synthetic oil mixtures (Synthol) by building up from carbon oxide and hydrogen, Brennstoff-Chem 4 (1923) 276. [5] F. Fischer, H. Tropsch, The synthesis of petroleum at atmospheric pressures from gasification products of coal, Brennstoff-Chem 7 (1926) 97. [6] D. Leckel, Diesel production from Fischer - Tropsch: the past, the present, and new concepts, Energy Fuels 23 (2009) 2342
2358. Available from: https://doi.org/10.1021/ef900064c. [7] M.E. Dry, The Fischer-Tropsch process: 1950
2000, Catal. Today. 71 (2002) 227
241. Available from: https://doi.org/10.1016/S0920-5861(01)00453-9. [8] M.E. Dry, The production of hydrocarbons from coal, Endeavour 8 (1984) 2
4. Available from: https://doi. org/10.1016/0160-9327(84)90121-2. [9] S.S. Ail, S. Dasappa, Biomass to liquid transportation fuel via Fischer Tropsch synthesis - Technology review and current scenario, Renew. Sustain. Energy Rev. 58 (2016) 267
286. Available from: https://doi.org/ 10.1016/j.rser.2015.12.143. [10] T.G. Kreutz, E.D. Larson, G. Liu, R.H. Williams, Fischer-Tropsch Fuels from Coal and Biomass, in: Proceedings of the Twenty-Fifth Annual International Pittsburgh Coal Conference, PCC - Proceedings, 2008. [11] M.J.A. Tijmensen, A.P.C. Faaij, C.N. Hamelinck, M.R.M. van Hardeveld, Exploration of the possibilities for production of Fischer Tropsch liquids and power via biomass gasification, Biomass Bioenergy 23 (2002) 129. Available from: https://doi.org/10.1093/nq/s6-VI.150.396-c. [12] K. Go¨ransson, U. So¨derlind, J. He, W. Zhang, Review of syngas production via biomass DFBGs, Renew. Sustain. Energy Rev. 15 (2011) 482
492. Available from: https://doi.org/10.1016/j.rser.2010.09.032. [13] O.O. James, A.M. Mesubi, T.C. Ako, S. Maity, Increasing carbon utilization in Fischer-Tropsch synthesis using H2-deficient or CO2-rich syngas feeds, Fuel Process. Technol. 91 (2010) 136
144. Available from: https://doi.org/10.1016/j.fuproc.2009.09.017. [14] D.S. Newsome, The water-gas shift reaction, Catal. Rev. 21 (1980) 275
318. Available from: https://doi.org/ 10.1080/03602458008067535. [15] D. Fo¨rtsch, K. Pabst, E. Groß-Hardt, The product distribution in Fischer-Tropsch synthesis: an extension of the ASF model to describe common deviations, Chem. Eng. Sci. 138 (2015) 333
346. Available from: https:// doi.org/10.1016/j.ces.2015.07.005. [16] O.O. James, B. Chowdhury, M.A. Mesubi, S. Maity, Reflections on the chemistry of the Fischer-Tropsch synthesis, RSC Adv. 2 (2012) 7347
7366. Available from: https://doi.org/10.1039/c2ra20519j. [17] G.P. Van Der Laan, A.A.C.M. Beenackers, Kinetics and selectivity of the Fischer-Tropsch synthesis: a literature review, Catal. Rev. Sci. Eng. 41 (1999) 255
318. Available from: https://doi.org/10.1081/CR-100101170. [18] H. Kuipers, E.W. Vinkenburg, I.H. Oosterbeek, Chain length dependence of alpha-olefins readsorption in Fischer-tropsh synthesis, J. Catal. 152 (1995) 137
146. [19] R.J. Madon, W.F. Taylor, Fischer-Tropsch synthesis on a precipitated iron catalyst, J. Catal. 69 (1981) 32
43. [20] F.G. Botes, Proposal of a new product characterization model for the iron-based low-temperature FischerTropsch synthesis, Energy Fuels 21 (2007) 1379
1389. Available from: https://doi.org/10.1021/ef060483d. [21] E. Visconti, C. Giorgio, L. Luca, T. Enrico, F. Pio, R. Zennaro, et al., Fischer
Tropsch synthesis on a Co/ Al2O3 catalyst with CO2 containing syngas, Appl Catal A Gen 355 (2009) 61
68. [22] M.K. Gnanamani, W.D. Shafer, D.E. Sparks, B.H. Davis, Fischer-Tropsch synthesis: effect of CO2 containing syngas over Pt promoted Co/γ-Al2O3 and K-promoted Fe catalysts, Catal. Commun. 12 (2011) 936
939. Available from: https://doi.org/10.1016/j.catcom.2011.03.002. [23] Y. Zhang, G. Jacobs, D.E. Sparks, M.E. Dry, B.H. Davis, CO and CO2 hydrogenation study on supported cobalt Fischer-Tropsch synthesis catalystsin:Catal. Today 71 (2002). Available from: https://doi.org/10.1016/ S0920-5861(01)00468-0.

Green Chemistry Approaches to Environmental Sustainability

212

10. Renewable and sustainable energy from CO2 following the green process

[24] S.M. Kim, J.W. Bae, Y.J. Lee, K.W. Jun, Effect of CO2 in the feed stream on the deactivation of Co/??-Al2O3 Fischer-Tropsch catalyst, Catal. Commun. 9 (2008) 2269
2273. Available from: https://doi.org/10.1016/j. catcom.2008.05.016. [25] S. Bahri, A.M. Venezia, S. Upadhyayula, Utilization of greenhouse gas carbon dioxide for cleaner FischerTropsch diesel production, J. Clean. Prod. 228 (2019) 1013
1024. Available from: https://doi.org/10.1016/j. jclepro.2019.04.310. [26] S. Bahri, T. Patra, S. Sonal, et al., Synergistic effect of bifunctional mesoporous ZSM-5 supported Fe-Co catalyst for selective conversion of syngas with low Ribblet ratio into synthetic fuel, Microporous Mesoporous Mater. 275 (2019) 1
13. Available from: https://doi.org/10.1016/j.micromeso.2018.08.004. [27] S. Krishnamoorthy, A. Li, E. Iglesia, Pathways for CO2 formation and conversion during Fischer 6 Tropsch synthesis on iron-based catalysts, Catal. Lett. 80 (2002) 77
86. Available from: https://doi.org/10.1023/ A:1015382811877. [28] Y. Liu, C.H. Zhang, Y. Wang, Y. Li, X. Hao, L. Bai, et al., Effect of co-feeding carbon dioxide on FischerTropsch synthesis over an iron-manganese catalyst in a spinning basket reactor, Fuel Process. Technol. 89 (2008) 234
241. Available from: https://doi.org/10.1016/j.fuproc.2007.11.002. [29] D. Chakrabarti, A. De Klerk, V. Prasad, M.K. Gnanamani, W.D. Shafer, G. Jacobs, et al., Conversion of CO2 over a Co-Based Fischer 2 Tropsch Catalyst, Ind. Eng. Chem. Res. 54 (2015) 1189
1196. Available from: https://doi.org/10.1021/ie503496m. [30] W.K. Hall, R.J. Kokes, P.H. Emmett, Mechanism studies of the Fischer-Tropsch synthesis. The addition of radioactive methanol, carbon dioxide and gaseous formaldehyde, J. Am. Chem. Soc. 79 (1957). [31] D. Chakrabarti, Investigation of Pathways of CO and CO2 in a Fischer-Tropsch System Using Tracer Studies, Development of Reaction Mechanism and Kinetic Expressions, 2015. [32] S. Badoga, M. Martinelli, M.K. Gnanamani, Y. Koh, W.D. Shafer, New mechanism insight for the hydrogenation of CO/CO2 gas mixtures to hydrocarbons over iron-based catalyst, Catal. Commun. 152 (2021) 106284. Available from: https://doi.org/10.1016/j.catcom.2021.106284. [33] Z.X. Wang, T. Dong, L.X. Yuan, T. Kan, X.F. Zhu, Y. Torimoto, et al., Characteristics of bio-oil-syngas and its utilization in Fischer-Tropsch synthesis, Energy Fuels 21 (2007) 2421
2432. Available from: https://doi.org/ 10.1021/ef0700275. [34] Y. Yao, X. Liu, D. Hildebrandt, D. Glasser, Fischer-Tropsch synthesis using H2/CO/CO2 syngas mixtures over an iron catalyst, Ind. Eng. Chem. Res. 50 (2011) 11002
11012. Available from: https://doi.org/10.1021/ ie200690y. [35] S. Tomasek, F. Lonyi, J. Valyon, A. Wollmann, J. Hancso´k, Hydrocracking of Fischer-Tropsch paraffin mixtures over strong acid bifunctional catalysts to engine fuels, ACS Omega 5 (2020) 26413
26420. Available from: https://doi.org/10.1021/acsomega.0c02711. [36] A. De Klerk, Fischer-Tropsch fuels refinery design, Energy Env. Sci. 4 (2011) 1177
1205. Available from: https://doi.org/10.1039/c0ee00692k. [37] D. Leckel, Low-pressure hydrocracking of coal-derived Fischer-Tropsch waxes to diesel, Energy Fuels 21 (2007) 1425
1431. Available from: https://doi.org/10.1021/ef060601x. [38] S. Sartipi, M. Makkee, F. Kapteijn, J. Gascon, Catalysis engineering of bifunctional solids for the one-step synthesis of liquid fuels from syngas: a review, Catal. Sci. Technol. 4 (2014) 893
907. Available from: https:// doi.org/10.1039/c3cy01021j. [39] C. Bouchy, G. Hastoy, E. Guillon, J.A. Martens, Fischer-Tropsch waxes upgrading via hydrocracking and selective hydroisomerization, Oil Gas. Sci. Technol. 64 (2009) 91
112. Available from: https://doi.org/ 10.2516/ogst/2008047. [40] S. Gamba, L.A. Pellegrini, V. Calemma, C. Gambaro, Liquid fuels from Fischer-Tropsch wax hydrocracking: Isomer distribution, Catal. Today 156 (2010) 58
64. Available from: https://doi.org/10.1016/j.cattod.2010.01.009. [41] H. Weyda, E. Ko¨hler, Modern refining concepts - an update on naphtha-isomerization to modern gasoline manufacture, Catal. Today 81 (2003) 51
55. Available from: https://doi.org/10.1016/S0920-5861(03)00101-9. [42] A. De Klerk, E. Furimsky, Catalysis in the refining of fischer-tropsch syncrude, 2011. https://doi.org/ 10.1595/147106711X593717. [43] S. Sartipi, M. Alberts, M.J. Meijerink, T.C. Keller, J. Pe´rez-Ramı´rez, J. Gascon, et al., Towards liquid fuels from biosyngas: effect of zeolite structure in hierarchical-zeolite-supported cobalt catalysts, ChemSusChem 6 (2013) 1646
1650. Available from: https://doi.org/10.1002/cssc.201300339.

Green Chemistry Approaches to Environmental Sustainability

References

213

[44] H. Schulz, Short history and present trends of Fischer-Tropsch synthesis, Appl. Catal. A Gen. 186 (1999) 3
12. Available from: https://doi.org/10.1016/S0926-860X(99)00160-X. [45] J. Zhang, M. Abbas, J. Chen, The evolution of Fe phases of a fused iron catalyst during reduction and Fischer-Tropsch synthesis, Catal. Sci. Technol. 7 (2017) 3626
3636. Available from: https://doi.org/10.1039/ c7cy01001j. [46] T.H. Pham, Y. Qi, J. Yang, X. Duan, G. Qian, X. Zhou, et al., Insights into Ha¨gg iron-carbide-catalyzed Fischer-Tropsch synthesis: suppression of CH4 formation and enhancement of C-C coupling on χ-Fe5C2 (510), ACS Catal. 5 (2015) 2203
2208. Available from: https://doi.org/10.1021/cs501668g. [47] B. Liu, W. Li, J. Zheng, Q. Lin, X. Zhang, J. Zhang, et al., CO2 formation mechanism in Fischer-Tropsch synthesis over iron-based catalysts: a combined experimental and theoretical study, Catal. Sci. Technol. 8 (2018) 5288
5301. Available from: https://doi.org/10.1039/c8cy01621f. [48] H. Jahangiri, J. Bennett, P. Mahjoubi, K. Wilson, S. Gu, A review of advanced catalyst development for Fischer-Tropsch synthesis of hydrocarbons from biomass derived syn-gas, Catal. Sci. Technol. 4 (2014) 2210
2229. Available from: https://doi.org/10.1039/c4cy00327f. [49] V.R. Calderone, N.R. Shiju, D.C. Ferre´, G. Rothenberg, Bimetallic catalysts for the Fischer-Tropsch reaction, Green. Chem. 13 (2011) 1950
1959. Available from: https://doi.org/10.1039/c0gc00919a. [50] J.A. Amelse, L.H. Schwartz, J.B. Butt, Iron alloy Fischer-Tropsch catalysts III. conversion dependence of selectivity and Water-Gas Shift, J. Catal. 72 (1981) 95
110. ´ lvarez-Galva´n, J.M. Campos-Martı´n, J.L.G. Fierro, Fischer-Tropsch synthesis [51] V.A. de la Pen˜a O’Shea, M.C. A on mono- and bimetallic Co and Fe catalysts in fixed-bed and slurry reactors, Appl. Catal. A Gen. 326 (2007) 65
73. Available from: https://doi.org/10.1016/j.apcata.2007.03.037. [52] H. Arai, K. Mitsuishi, T. Seiyama, TiO2-suported Fe-Co, Co-Ni and Ni-Fe alloy catalysts for Fischer-Tropsch synthesis, Chem. Lett. 13 (1984) 1291
1294. [53] T. Ishihara, K. Eguchi, H. Arai, Hydrogenation of Carbon monoxide over SiO2- supported Fe-Co, Co-Ni and Ni-Fe bimetallic catalysts, Appl. Catal. 30 (1987) 225. [54] X. Ma, Q. Sun, W. Ying, D. Fang, Effects of promoters on catalytic performance of Fe-Co/SiO2 catalyst for Fischer-Tropsch synthesis, J. Nat. Gas. Chem. 18 (2009) 354
358. Available from: https://doi.org/10.1016/ S1003-9953(08)60115-2. [55] Y. Bi, A.K. Dalai, Selective Production of C4 Hydrocarbons from syngas using Fe-CO/ZrO2 and SO42-/ZrO2 catalysts, Can. J. Chem. Eng. 81 (2003) 230
242. [56] T.A. Lin, L.H. Schwartz, J.B. Butt, Iron alloy Fischer-Tropsch catalysts V. FeCo on Y zeolite, J. Catal. 187 (1986) 177
187. [57] C.F. Tonco´n-Leal, J.F. Mu´nera, J.J. Arroyo-Go´mez, K. Sapag, Fe, Co and Fe/Co catalysts supported on SBA15 for Fischer-Tropsch Synthesis, Catal. Today (2021). Available from: https://doi.org/10.1016/j. cattod.2021.07.023. [58] A.S.M. Ismail, M. Casavola, B. Liu, A. Gloter, T.W. Van Deelen, M. Versluijs, et al., Atomic-scale investigation of the structural and electronic properties of cobalt-iron bimetallic Fischer-Tropsch catalysts, ACS Catal. 9 (2019) 7998
8011. Available from: https://doi.org/10.1021/acscatal.8b04334. [59] Y. Zhai, Y. Xue, Z. Chen, M. Chen, B. Wang, J. Chen, Study on Fe-Co alloy role over RANEY Fe-Co bimetallic catalysts in Fischer-Tropsch synthesis, RSC Adv. 6 (2016) 101683
101687. Available from: https://doi.org/ 10.1039/C6RA22785F. [60] L.F.F.P.G. Braganca, M. Ojeda, J.L.G. Fierro, M.I.P. Da Silva, Bimetallic Co-Fe nanocrystals deposited on SBA-15 and HMS mesoporous silicas as catalysts for Fischer-Tropsch synthesis, Appl. Catal. A Gen. 423 424 (2012) 146
153. Available from: https://doi.org/10.1016/j.apcata.2012.02.031. [61] A. Tavasoli, M. Tre´panier, R.M. Malek Abbaslou, A.K. Dalai, N. Abatzoglou, Fischer-Tropsch synthesis on mono- and bimetallic Co and Fe catalysts supported on carbon nanotubes, Fuel Process. Technol. 90 (2009) 1486
1494. Available from: https://doi.org/10.1016/j.fuproc.2009.07.007. [62] S. Lo¨gdberg, D. Tristantini, Ø. Borg, L. Ilver, B. Gevert, S. Ja¨ra˚s, et al., Hydrocarbon production via FischerTropsch synthesis from H2-poor syngas over different Fe-Co/γ-Al2O3 bimetallic catalysts, Appl. Catal. B 89 (2009) 167
182. Available from: https://doi.org/10.1016/j.apcatb.2008.11.037. [63] D.J. Duvenhage, N.J. Coville, Fe:Co/TiO2 bimetallic catalysts for the Fischer-Tropsch reaction: Part 4: a study of nitrate and carbonyl derived FT catalysts, J. Mol. Catal. A Chem 235 (2005) 230
239. Available from: https://doi.org/10.1016/j.molcata.2005.04.029.

Green Chemistry Approaches to Environmental Sustainability

214

10. Renewable and sustainable energy from CO2 following the green process

[64] N.J.C.D.J. Duvenhage, Fe:Co/TiO2 bimetallic catalysts for the Fischer-Tropsch reaction I. Characterization and reactor studies, Appl Catal A Gen 153 (1997) 43
67. [65] M.E. Dry, Fischer-Tropsch reactions and the environment, Appl. Catal. A Gen. 189 (1999) 185
190. Available from: https://doi.org/10.1016/S0926-860X(99)00275-6. [66] V.A. De la Pen˜a O’Shea, N.N. Mene´ndez, J.D. Tornero, J.L.G. Fierro, Unusually high selectivity to C2 1 alcohols on bimetallic CoFe catalysts during CO hydrogenation, Catal. Lett. 88 (2003) 123
128. Available from: https://doi.org/10.1023/A:1024097319352. [67] S. Jam, M.G. Ahangary, A. Tavasoli, K. Sadaghiani, A. Nakhaei Pour, Enhancement of distillate selectivity in Fischer-Tropsch synthesis by using iron and cobalt catalysts in a novel dual-bed reactor, React. Kinetics Catal. Lett. 89 (2006) 71
79. Available from: https://doi.org/10.1007/s11144-006-0088-1. [68] F. Yuan, G. Zhang, J. Zhu, F. Ding, A. Zhang, C. Song, et al., Boosting light olefin selectivity in CO2 hydrogenation by adding Co to Fe catalysts within close proximity, Catal. Today (2020). Available from: https:// doi.org/10.1016/j.cattod.2020.07.072. [69] K.Y. Kim, H. Lee, W.Y. Noh, J. Shin, S.J. Han, S.K. Kim, et al., Cobalt ferrite nanoparticles to form a catalytic Co-Fe Alloy carbide phase for selective CO2 hydrogenation to light olefins, ACS Catal. 10 (2020) 8660
8671. Available from: https://doi.org/10.1021/acscatal.0c01417. [70] P.J. Van Berge, J. Van De Loosdrecht, S. Barradas, A.M. Van Der Kraan, Oxidation of cobalt based FischerTropsch catalysts as a deactivation mechanism, Catal. Today 58 (2000) 321
334. Available from: https://doi. org/10.1016/S0920-5861(00)00265-0. [71] A.M. Saib, A. Borgna, J. van de Loosdrecht, P.J. van Berge, J.W. Niemantsverdriet, XANES study of the susceptibility of nano-sized cobalt crystallites to oxidation during realistic Fischer-Tropsch synthesis, Appl. Catal. A Gen. 312 (2006) 12
19. Available from: https://doi.org/10.1016/j.apcata.2006.06.009. [72] G.Z. Bian, N. Fujishita, T. Mochizuki, W.S. Ning, M. Yamada, Investigations on the structural changes of two Co/SiO2 catalysts by performing Fischer-Tropsch synthesis, Appl. Catal. A Gen. 252 (2003) 251
260. Available from: https://doi.org/10.1016/S0926-860X(03)00470-8. [73] B. Jager, P. van Berge, A.P. Steynberg, Developments in Fischer-Tropsch technology and its application, Stud. Surf. Sci. Catal. 136 (2001) 63. [74] M.D. Strømsheim, I.H. Svenum, M.H. Farstad, C.J.K.J. Weststrate, A. Borg, H.J. Venvik, CO-induced surface reconstruction of the Co(11
20) surface - a combined theoretical and experimental investigation, J. Phys. Chem. C. 124 (2020) 28488
28499. Available from: https://doi.org/10.1021/acs.jpcc.0c07852. [75] J.B. Butt, L.H. Schwartz, M. Baerns, R. Malessa, Comparison of activity and selectivity maintenance for supported Fe and FeCo Fischer-Tropsch catalysts, Ind. Eng. Chem. Product. Res. Dev. 23 (1984) 51
56. Available from: https://doi.org/10.1021/i300013a010. [76] Y. Yao, D. Hildebrandt, D. Glasser, X. Liu, Fischer-tropsch synthesis using H2/CO/CO2 syngas mixtures over a cobalt catalyst, Ind. Eng. Chem. Res. 49 (2010) 11061
11066. Available from: https://doi.org/10.1021/ie100414y. [77] J.A. Dı´az, A.R. De La Osa, P. Sa´nchez, A. Romero, J.L. Valverde, Influence of CO2 co-feeding on FischerTropsch fuels production over carbon nanofibers supported cobalt catalyst, Catal. Commun. 44 (2014) 57
61. Available from: https://doi.org/10.1016/j.catcom.2013.07.033. [78] E. Sonal, S. Ahmad, K.K.P. Upadhyayula, Biomass-derived CO2 rich syngas conversion to higher hydrocarbon via Fischer-Tropsch process over Fe
Co bimetallic catalyst, Int. J. Hydrog. Energy 44 (2019) 27741
27748. Available from: https://doi.org/10.1016/j.ijhydene.2019.09.015. [79] Y. Lu, Q. Yan, J. Han, B. Cao, J. Street, F. Yu, Fischer-Tropsch synthesis of olefin-rich liquid hydrocarbons from biomass-derived syngas over carbon-encapsulated iron carbide / iron nanoparticles catalyst, Fuel 193 (2017) 369
384. Available from: https://doi.org/10.1016/j.fuel.2016.12.061. [80] M. Rafati, L. Wang, A. Shahbazi, Effect of silica and alumina promoters on co-precipitated Fe-Cu-K based catalysts for the enhancement of CO2 utilization during Fischer-Tropsch synthesis, J. CO2 Utilization 12 (2015) 34
42. Available from: https://doi.org/10.1016/j.jcou.2015.10.002. [81] Y. Li, X. Qin, T. Wang, L. Ma, L. Chen, N. Tsubaki, Fischer Tropsch synthesis from H2-deficient biosyngas over Mn added Co/SiO2 catalysts, Fuel 136 (2014) 130
135. Available from: https://doi.org/10.1016/j. fuel.2014.06.048. [82] Q. Yan, Y. Lu, C. Wan, J. Han, J. Rodriguez, J.J. Yin, et al., Synthesis of aromatic-rich gasoline-range hydrocarbons from biomass-derived syngas over a pd-promoted Fe/HZSM-5 catalyst, Energy Fuels 28 (2014) 2027
2034. Available from: https://doi.org/10.1021/ef402507u.

Green Chemistry Approaches to Environmental Sustainability

References

215

[83] Q. Yan, F. Yu, J. Liu, J. Street, J. Gao, Z. Cai, et al., Catalytic conversion wood syngas to synthetic aviation turbine fuels over a multifunctional catalyst, Bioresour. Technol. 127 (2013) 281
290. Available from: https://doi.org/10.1016/j.biortech.2012.09.069. [84] Q. Yan, C. Wan, J. Liu, J. Gao, F. Yu, J. Zhang, et al., Iron nanoparticles in situ encapsulated in biocharbased carbon as an effective catalyst for the conversion of biomass-derived syngas to liquid hydrocarbons, Green. Chem. 15 (2013) 1631
1640. Available from: https://doi.org/10.1039/c3gc37107g. [85] R.C. Brady, R. Pettit, On the mechanism of the Fischer-Tropsch Reaction. The chain propagation step, J. Am. Chem. Soc. 103 (1981) 1287
1289. Available from: https://doi.org/10.1021/ja00395a081. [86] P. Johnston, R.W. Joyner, Structure-Function Relationships in Heterogeneous Catalysis: The Embedded Surface Molecule Approach and Its Applications, Stud. Surf. Sci. Catal. 75 (1993) 165
180. Available from: https://doi.org/10.1016/S0167-2991(08)64008-2. [87] P.M. Maitlis, R. Quyoum, H.C. Long, M.L. Turner, Towards a chemical understanding of the FischerTropsch reaction: alkene formation, Appl. Catal. A Gen. 186 (1999) 363
374. Available from: https://doi. org/10.1016/S0926-860X(99)00155-6. [88] P.M. Maitlis, Fischer-Tropsch, organometallics, and other friends, J. Organomet. Chem. 689 (2004) 4366
4374. Available from: https://doi.org/10.1016/j.jorganchem.2004.05.037. [89] P.M. Maitlis, H.C. Long, R. Quyoum, M.L. Turner, Z.Q. Wang, Heterogeneous catalysis of C-C bond formation: Black art or organometallic science? Chem. Commun. (1996) 1
8. Available from: https://doi.org/ 10.1039/CC9960000001. [90] H.H. Storch, The Fischer-Tropsch and related processes for synthesis of hydrocarbons by hydrogenation of carbon monoxide, Adv. Catal. 1 (1948) 115
156. Available from: https://doi.org/10.1016/S0360-0564(08)60674-4. [91] H. Pichler, H. Schulz, Recent findings in the synthesis of hydrocarbons from CO and H2, Chem. Ing. Tech. 42 (1970) 1164
1174. [92] M.E. Dry, The Fischer-Tropsch process - commercial aspects, Catal. Today 6 (1990) 183
206. Available from: https://doi.org/10.1016/0920-5861(90)85002-6. [93] K.G. Anderson, J.G. Ekerdt, Study of Fischer-Tropsch synthesis over Fe SiO2: effect of diethylamine on hydrocarbon and alcohol production, J. Catal. 95 (1985) 602
604. Available from: https://doi.org/10.1016/ 0021-9517(85)90138-1. [94] R.B. Anderson, Catalysis Vol. IV, Hydrocarbon Synthesis, Hydrogenation and Cyclization, 1956. [95] G.A. Huff, C.N. Satterfield, Intrinsic kinetics of the Flscher-Tropsch synthesis fused-magnetite catalyst, Ind. Eng. Chem. Process. Des. Dev. 23 (1984) 696
705. [96] G.P. Van Der Laan, A.A.C.M. Beenackers, Intrinsic kinetics of the gas-solid Fischer-Tropsch and water gas shift reactions over a precipitated iron catalyst, Appl. Catal. A Gen. 193 (2000) 39
53. Available from: https://doi.org/10.1016/S0926-860X(99)00412-3. [97] R. Zennaro, M. Tagliabue, C.H. Bartholomew, Kinetics of Fischer-Tropsch synthesis on titania-supported cobalt, Catal. Today 58 (2000) 309
319. Available from: https://doi.org/10.1016/S0920-5861(00)00264-9. [98] A. Outi, I. Rautavuoma, H.S. van der Baan, Kinetics and Mechanism of the Fischer-Tropsch hydrocarbon synthesis on a cobalt on alumina catalyst, Appl. Catal. 1 (1981) 247
272. Available from: https://doi.org/ 10.1016/0166-9834(81)80031-0. [99] B. Sarup, B.W. Wojciechowski, Studies of the fischer-tropsch synthesis on a cobalt catalyst i. Evaluation of product distribution parameters from experimental data, Can. J. Chem. Eng. 66 (1988) 831
842. Available from: https://doi.org/10.1002/cjce.5450660518. [100] I.C. Yates, C.N. Satterfield, Intrinsic Kinetics of the Fischer-Tropsch synthesis on a cobalt catalyst, Energy Fuels 5 (1991) 168
173. Available from: https://doi.org/10.1021/ef00025a029. [101] T. Bhatelia, W. Ma, B. Davis, G. Jacobs, G. Drabukur, Kinetics of the Fischer-Tropsch reaction over a Rupromoted Co/Al2O3 catalyst, Chem. Eng. Trans. 25 (2011) 707
712. Available from: https://doi.org/ 10.3303/CET1125118. [102] S. Vahid, A.A. Mirzaei, An investigation of the kinetics and mechanism of Fischer-Tropsch synthesis on FeCo-Ni supported catalyst, J. Ind. Eng. Chem. 20 (2014) 2166
2173. Available from: https://doi.org/ 10.1016/j.jiec.2013.09.047. [103] A. Eshraghi, A.A. Mirzaei, R. Rahimi, H. Atashi, Effect of Ni
Co morphology on kinetics for Fischer
Tropsch reaction in a fixed-bed reactor, J. Taiwan. Inst. Chem. Eng. 105 (2019) 104
114. Available from: https://doi.org/10.1016/j.jtice.2019.09.014.

Green Chemistry Approaches to Environmental Sustainability

216

10. Renewable and sustainable energy from CO2 following the green process

[104] F. Fazlollahi, M. Sarkari, H. Gharebaghi, H. Atashi, M.M. Zarei, A.A. Mirzaei, et al., Preparation of Fe-Mn/ K/Al2O3 Fischer-Tropsch catalyst and its Catalytic Kinetics for the Hydrogenation of Carbon Monoxide, Chin. J. Chem. Eng. 21 (2013) 507
519. Available from: https://doi.org/10.1016/S1004-9541(13)60503-0. [105] M. Ojeda, R. Nabar, A.U. Nilekar, A. Ishikawa, M. Mavrikakis, E. Iglesia, CO activation pathways and the mechanism of Fischer-Tropsch synthesis, J. Catal. 272 (2010) 287
297. Available from: https://doi.org/ 10.1016/j.jcat.2010.04.012. [106] H. Atashi, F. Siami, A.A. Mirzaei, M. Sarkari, Kinetic study of Fischer-Tropsch process on titania-supported cobalt-manganese catalyst, J. Ind. Eng. Chem. 16 (2010) 952
961. Available from: https://doi.org/10.1016/j. jiec.2010.04.005. [107] K. Sonal, K.K. Kondamudi, S. Pant, Upadhyayula, Synergistic effect of Fe-Co bimetallic catalyst on FTS and WGS Activity in the Fischer-Tropsch Process: A Kinetic Study, Ind. Eng. Chem. Res. 56 (2017) 4659
4671. Available from: https://doi.org/10.1021/acs.iecr.6b04517. [108] F. Fazlollahi, M. Sarkari, A. Zare, A.A. Mirzaei, H. Atashi, Development of a kinetic model for FischerTropsch synthesis over Co/Ni/Al2O3 catalyst, J. Ind. Eng. Chem. 18 (2012) 1223
1232. Available from: https://doi.org/10.1016/j.jiec.2011.10.011. [109] M. Sarkari, F. Fazlollahi, H. Atashi, A.A. Mirzaei, V. Hosseinpour, Fischer-Tropsch synthesis: development of kinetic expression for a sol-gel Fe-Ni/Al2O3 catalyst, Fuel Process. Technol. 97 (2012) 130
139. Available from: https://doi.org/10.1016/j.fuproc.2012.01.008. [110] N. Mohammad, S. Bepari, S. Aravamudhan, D. Kuila, Kinetics of Fischer-Tropsch synthesis in a 3-D printed stainless steel microreactor using a different mesoporous silica supported Co-Ru catalysts, Catalysts. 9 (2019) 872. [111] M. Abbasi, A.A. Mirzaei, H. Atashi, The mechanism and kinetics study of Fischer-Tropsch reaction over iron-nickel-cerium nano-structure catalyst, Int. J. Hydrog. Energy 44 (2019) 24667
24679. Available from: https://doi.org/10.1016/j.ijhydene.2019.07.222. [112] K. Sonal, K.K. Kondamudi, S. Pant, Upadhyayula, Synergistic effect of Fe-Co bimetallic catalyst on FTS and WGS activity in the Fischer-Tropsch process: a kinetic study, Ind. Eng. Chem. Res. 56 (2017) 4659
4671. Available from: https://doi.org/10.1021/acs.iecr.6b04517. [113] A.N. Pour, M.R. Housaindokht, J. Zarkesh, M. Irani, E.G. Babakhani, Kinetics study of CO hydrogenation on a precipitated iron catalyst, J. Ind. Eng. Chem. 18 (2012) 597
603. Available from: https://doi.org/ 10.1016/j.jiec.2011.11.080. [114] S.A. Eliason, C.H. Bartholomew, Reaction and deactivation kinetics for Fischer-Tropsch synthesis on unpromoted and potassium-promoted iron catalysts, Appl. Catal. A Gen. 186 (1999) 229
243. Available from: https://doi.org/10.1016/S0926-860X(99)00146-5. [115] A.A. Mirzaei, R. Sarani, H.R. Azizi, S. Vahid, H.O. Torshizi, Kinetics modeling of Fischer-Tropsch synthesis on the unsupported Fe-Co-Ni (ternary) catalyst prepared using co-precipitation procedure, Fuel 140 (2015) 701
710. Available from: https://doi.org/10.1016/j.fuel.2014.09.093. [116] S. Golestan, A.A. Mirzaei, H. Atashi, Kinetic and mechanistic studies of Fischer-Tropsch synthesis over the nano-structured iron
cobalt
manganese catalyst prepared by hydrothermal procedure, Fuel 200 (2017) 407
418. Available from: https://doi.org/10.1016/j.fuel.2017.03.087. [117] R.B. Anderson, F.S. Karn, J.F. Shultz, Kinetics of the Fischer-Tropsch Synthesis on Iron Catalysts, 1964. https://doi.org/10.1021/j150567a004. [118] W.H. Zimmerman, D.B. Bukur, Reaction kinetics over iron catalysts used for the Fischer-Tropsch synthesis, Can. J. Chem. Eng. 68 (1990) 292
301. Available from: https://doi.org/10.1002/cjce.5450680215. [119] F.G. Botes, The effects of water and CO2 on the reaction kinetics in the iron-based low-temperature FischerTropsch synthesis: a literature review, Catal. Rev. Sci. Eng. 50 (2008) 471
491. Available from: https://doi. org/10.1080/01614940802477250. [120] B. Sarup, B.W. Wojciechowski, Studies of the fischer-tropsch synthesis on a cobalt catalyst II. Kinetics of carbon monoxide conversion to methane and to higher hydrocarbons, Can. J. Chem. Eng. 67 (1989) 62
74. Available from: https://doi.org/10.1002/cjce.5450670110. [121] M.E. Dry, Practical and theoretical aspects of the catalytic Fischer-Tropsch process, Appl. Catal. A Gen. 138 (1996) 319
344. Available from: https://doi.org/10.1016/0926-860X(95)00306-1. [122] S. Ledakowic, H. Nettelhoff, R. Kokuum, W.-D. Deckwer, Kinetics of the Fiscehr-Trospch synthesis in the slurry phase on a pottasium-promoted iron catalyst, Ind. Eng. Chem. Process. Des. Dev. 24 (1985) 1043
1049.

Green Chemistry Approaches to Environmental Sustainability

References

217

[123] I.C. Yates, C.N. Satterfield, Effect of carbon dioxide on the kinetics of the Fischer-Tropsch synthesis on iron catalysts, Ind. Eng. Chem. Res. 28 (1989) 9
12. Available from: https://doi.org/10.1021/ie00085a003. [124] F.G. Botes, B.B. Breman, Development of a new kinetic expression for the iron-based Fischer-Tropsch reaction, AIChE Annual Meeting, Conference Proceedings. (2006) 7415
7426. [125] L.P. Zhou, X. Hao, J.H. Gao, Y. Yang, B.S. Wu, J. Xu, et al., Studies and discriminations of the kinetic models for the iron-based Fischer-Tropsch catalytic reaction in a recycle slurry reactor, Energy Fuels 25 (2011) 52
59. Available from: https://doi.org/10.1021/ef101270u. [126] M.J. Keyser, R.C. Everson, R.L. Espinoza, Fischer-Tropsch kinetic studies with cobalt-manganese oxide catalysts, Ind. Eng. Chem. Res. 39 (2000) 48
54. Available from: https://doi.org/10.1021/ie990236f. [127] T.K. Das, X. Zhan, J. Li, G. Jacobs, M.E. Dry, B.H. Davis, Fischer-Tropsch synthesis: kinetics and effect of water for a Co/Al2O3 catalyst, Stud. Surf. Sci. Catal. 163 (2007) 289. Available from: https://doi.org/ 10.1142/9789812793331_0135. [128] W. Ma, G. Jacobs, D.E. Sparks, J.L.S. Klettlinger, C.H. Yen, B.H. Davis, Fischer
Tropsch synthesis and water gas shift kinetics for a precipitated iron catalyst, Catal. Today 275 (2016) 49
58. Available from: https:// doi.org/10.1016/j.cattod.2016.01.006. [129] S. Ghosh, V. Uday, A. Giri, S. Srinivas, Biogas to methanol: a comparison of conversion processes involving direct carbon dioxide hydrogenation and via reverse water gas shift reaction, J. Clean. Prod. 217 (2019) 615
626. Available from: https://doi.org/10.1016/j.jclepro.2019.01.171. [130] T. Riedel, M. Claeys, H. Schulz, et al., Comparative study of Fischer
Tropsch synthesis with H2/CO and H2/CO2 syngas using Fe- and Co- based catalysts, Appl. Catal. A Gen. 186 (1999) 201
213. [131] V. Perrichon, M. Pijolat, M. Primet, Surface species involved during the hydrogenation of CO or CO2 on iron-alumina catalysts, J. Mol. Catal. 25 (1984) 207
217. Available from: https://doi.org/10.1016/0304-5102 (84)80044-9. [132] G. Jacobs, E. Chenu, P.M. Patterson, L. Williams, D. Sparks, G. Thomas, et al., Water-gas shift: comparative screening of metal promoters for metal/ceria systems and role of the metal, Appl. Catal. A Gen. 258 (2004) 203
214. Available from: https://doi.org/10.1016/j.apcata.2003.09.007.

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C H A P T E R

11 Use of renewable feedstocks for chemical synthesis Shivani Verma1, Sanjeev Verma2, Akansha Agrwal3 and Saurabh Kumar4 1

Department of Chemistry, G. B. Pant University, Pantnagar, Uttarakhand, India 2Department of Chemical Engineering & Technology, IIT(BHU) Varanasi, Varanasi, Uttar Pradesh, India 3 Department of Applied Sciences, KIET Group of Institutions, Delhi-NCR, Ghaziabad, Uttar Pradesh, India 4Department of Electronics and Communication Engineering, NIT Hamirpur, Hamirpur, Himachal Pradesh, India

11.1 Introduction Chemistry has a long history of producing necessary and helpful products via environmental friendly methodology with improved performances; unfortunately, this technical advancement has frequently been achieved using a restricted definition of function that ignores negative implications [1]. Many chemical industries focus on designing of chemical products and processes through performance metrics, not on the phenomenon of persistence on water and soil, degrading water and food causing bioaccumulation in our bodies and the biosphere [2 4]; however, this strategy is not enough. Therefore we need transformational, disruptive solutions to fulfil all ecofriendly conditions on a long-term basis to obtain desired product. To find solutions that do not have impacts or have unintended implications elsewhere, systems must be addressed in their entirety [5,6]. Mainly, scientific challenges facing the chemical industry when building a sustainable environment is not whether its products will be formed, because they will undoubtedly be. Rather, what will be the nature, character, production procedures and synthesis steps of synthetic products required for a long-term sustainability? Currently, a desired chemical reagent involves mainly two goals: (1) maintenance and considerably enhancement of performance for particular path of reaction [7,8] (2) decreasing or eliminating the negative consequences that undermine human and planetary well-being [9 11]. Today’s chemical industry follows a linear simple pathway (Fig. 11.1, left), in which finite and fossil

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FIGURE 11.1

11. Use of renewable feedstocks for chemical synthesis

Present and future status of chemical industries.

feedstocks are going through a generation pathway that are designed to be highly reactive but their persistence or toxic nature creates risk factor to living beings. These processes create waste (e.g., toxic material, persistent phenomenon, and bioaccumulation processes) at higher rates than the final result, especially when products are complex in nature. So, we must change not just the settings and circumstances under which we create and utilize chemical products, but also the intrinsic character of chemical reactants and products across the whole stepwise chain, from feedstock to final application (Fig. 11.1) [12]. This necessitates a shift in the notion of “performance” from “function alone” to “function and sustainability”, which can achieve via careful consideration of the molecules’ fundamental features and changes. The chemical industry’s economic model is directly affected by the redefining of performance, because one aspect of the strategy for decreasing negative effects is to minimize the amount of material required, hence decreasing damage potential over the whole life cycle. Future goal of chemical industries is to enhance function while decreasing harmful chemical and material bulk. Of course, reducing mass is meant to be lowering the quantity of feedstock material, methodology and transportation energy, manufacturing waste by-products, and reusability with management. This lowers total production costs and prioritizes efficiency and their efficacy in that ways which optimize profitability while being sustainable (Fig. 11.1, Right) [13,14]. The chemical industry has become highly regulated in recent decades in order to limit harmful emissions and effluents while also ensuring worker safety. The industry has discovered that working with environmental legislators is often the best option. Therefore green chemistry aims to make entire chemical processes less wasteful and harmful to the environment. The need for sustainable resource usage, environmentally safe processes and products will become more essential as the world population grows and living standards in developing countries [15]. Despite other things, the continuous development and

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awareness in the field of chemistry during 18th to 21st century is the golden era of chemistry in the form of green chemistry, addressing directly to introduce new technologies for the formation of chemical products that can reduce hazardous substances elimination [16,17].

11.2 Green chemistry Synthetic chemistry is the discipline of chemical research concerned with creating new molecules and improving methods of synthesizing existing ones [18]. The engagement of synthetic chemists in environmental chemistry is an important aspect of green chemistry. There are two general and often complementary approaches to implementing green chemistry in chemical synthesis, both of which test chemists’ and chemical engineers’ ideas and ingenuity. The first is to utilize existing feedstocks but produce them through more environmentally friendly, “greener” processes. The second option is to substitute different feedstocks produced in environmentally friendly ways. In other circumstances, a hybrid of the two approaches is employed. Incredible developments being made in the field of green chemistry on a daily basis is quickly gaining popularity in the world. It primarily concentrates on issues related to waste minimization in the synthesis of products, particularly when using alternative solvent like supercritical carbon dioxide and ionic liquids. It also focuses on without solvent reaction, oxidation process, catalysis, renewable energy sources and energy usage, enhancing atom efficiency and toxicity reduction. There have been numerous accomplishments in the domains of green chemistry and their engineering that show better performance and functionality of our chemical processes with decreasing adverse effects [9,19,20]. To succeed, we must change not just the circumstances under which we create and utilize chemical products, but also the nature of desired chemical products and intermediates across the entire chain system, from initial process to final application. This requires not only performance and sustainability but also modified intrinsic properties of reactants, involving pathway and their transformations. The term “green chemistry” refers to “the invention, design and application of chemical products and processes to reduce or to eliminate the use and generation of hazardous substance” [18,21]. It relates to the protection of environment and associated environmental factors from hazardous substances by protecting and monitoring conditions of water, air and soil. Paul Anastas and John Warner introduced the Green Chemistry Twelve Principles in 1998. They currently serve as a framework for the synthesis of new methodology of chemical processes, encompassing all aspects of the whole cycle, from raw materials to final product transformation with improved efficiency and higher efficacy with reduced toxicity factor and biodegradability of the final products [22]. Recently, they were condensed into more convenient abbreviation PRODUCTIVELY [23]. The green chemistry principles are: (1) Prevention, and avoiding waste formation is preferable to cleaning up after it has already formed. Depending on its type, toxicity, quantity or method of release, waste can take various forms and have varying effects on the environment. A process will unavoidably produce waste, which is by definition unwanted, if significant amounts of the starting materials employed in the reaction process are lost due to the old design.

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Environmental impact factor, often known as E-factor, is a notion that makes it easier to determine how much waste is generated per kilogram of product. It decides, if a manufacturing process is “environmentally acceptable”. (2) Atom economy, atom efficiency (AE) is another name for atom economy. It refers to the idea of utilizing raw materials as efficiently as possible so that the finished product has most atoms from the reactants. All the atoms of the reactants should be included in the perfect reaction. (3) Chemical synthesis with less hazardous or by-products release, synthetic designing methodologies are neither dangerous to humans nor the environment up to final product formation. (4) Design safer and less hazardous chemicals, chemical substances should be created to maintain function efficacy while lowering toxicity. Sustainability depends on our capacity to comprehend how molecular characteristics affect the environment and how the biosphere changes. Chemistry can create molecules that are safer for people and the environment. (5) Safer solvents and auxiliaries, the most active area of study in green chemistry is solvents. They pose a significant obstacle for green chemistry since they frequently make up the bulk of the mass lost during synthesis and processing. They have caused significant mishaps and resulted in increased risk of workers because of their volatility and solubility, which have also contributed to air, water and land contamination. Chemists have started search for safer alternatives to solve all of these issues. (6) Designing of energy efficient method, chemical processes energy efficiency explained in terms of their effects on the environment and economy. Synthetic procedures can be carried out if it can work at desired pressure and room temperature. (7) Use of renewable feedstocks, wherever it is technically and economically viable, a raw material or feedstock should be renewable rather than finite. It is now more important than ever to switch to renewable feedstocks for both fuel and building materials. Biomass, the substance derived from living creatures, is the primary renewable feedstock on the planet for both material and energy. This comprises food, agricultural waste, timber and other materials. (8) Reduce derivatization, use of blocking, protection/deprotection groups with temporary alteration of physical or chemical processes exhibit unnecessary derivatization that should be reduced or avoided whenever feasible since they need advanced methodology and knowledge. (9) Catalysis, the conventional use of a stoichiometric quantity of chemicals is frequently associated with the creation of waste. One significant strategy to increase the effectiveness of the synthetic toolkit is to switch from stoichiometric techniques to catalytic procedures. By reducing the amount of energy needed, eliminating the usage of stoichiometric amounts of chemicals and increasing product selectivity, catalysis can increase a reaction’s efficiency [24]. (10) Design for easy degradation, final desired product should be made or design on that way, which easily degrades into nontoxic degradation products. (11) Real-time examination for pollution control, in which process monitoring and control before the creation of hazardous compounds, used methodologies and technologies can be improved. (12) Chemicals and the form of a material used in a chemical process should be chosen carefully to avoid the likelihood of chemical accidents, such as leaks, explosions and fires. (Fig. 11.2). Role of sustainability in catalytic, synthetic, photochemistry and analytical chemistry, which is a major approach of green chemistry to change in future perspective of environment concern [25 32]. In this chapter, we discuss details about the seventh “Principle of green chemistry” that can be utilized as renewable feedstock in synthetic chemistry.

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11.3 Renewable feedstocks and renewable energy

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FIGURE 11.2 Green chemistry principles.

11.3 Renewable feedstocks and renewable energy Renewable feedstocks are the raw materials that can be reusable rather than depleted. The major challenge comes in such a way to develop the nontoxic, energy conservative, cost-effective and reduction of waste pathways for chemical processes by the use of renewable or sustainable resources. The minimum energy associated with chemical processes occurs via renewable feedstocks called renewable energy. Due to emission of greenhouse gases by the use of petroleum, development of renewable resources like biomass as the renewable feedstock for the chemical industries is the essential criteria. The designing of used chemical products from renewable sources, like biomass, is clear and wide to our daily lives and our environment. An important global project for putting the planet on a sustainable trajectory is the switch to using biomass as a renewable green feedstock and an energy source [20]. Biomass-based chemicals will serve as a “supply chain” for the chemical synthetic industry to change into a wide variety of molecules. These will undoubtedly be based on green chemistry, making use of the earlier attention paid to the subject as outlined above as well as ongoing discoveries. The aforementioned “waste” ought to be viewed as a useful resource for emerging innovations. In actuality, all types of biomass, including the leftovers from their chemical processing, have the potential to be renewable sources of energy. The transition to biomass-based renewable feedstocks is a daunting task, and much work remains to be done. Despite this, little attention has been paid to programme involving the utilization of biomass [33]. Any naturally occurring compound having minimally processed, high-value added energy fuel, which was utilized for the synthesis of desired products and further used as the same feedstock process for future final products, is known as a feedstock. It mainly

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11. Use of renewable feedstocks for chemical synthesis

belongs to the raw materials. Besides this, we can use waste of fisheries, agriculture, aquaculture and plantations, as well as biomass from crops grown just for biomass. The use of natural resources from animals, plants, marine organisms and microorganisms as renewable feedstocks in the chemical synthetic industry having important aspects towards human beings as well as for healthy environment [34,35]. These naturally occurring sources involve drugs, metabolites, essential oils, polymers, biofuels, renewable solvents and energy-based compounds [36 38]. The chemical industry is focusing on the use of raw materials produced from renewable feedstock since vegetable oils are one of the most essential platform chemicals due to their universal availability, intrinsic biodegradability and low cost [39]. Any material derived from living organisms, most frequently plants, is referred to as biomass, which is a renewable feedstock. We can easily create more plants once we have used them up to maintain a consistent supply, unlike depleting feedstocks like petroleum. Our goal of having a consistent, dependable supply of resources in future will be one step closer if we can use biobased chemicals to carry out the same tasks as petrochemicals. The chemical industry consumes a lot of raw materials and energy [40]. Because of the shortage of fossil resources, rising oil prices and the need to minimize greenhouse gas emissions, renewable feed stocks have become a more critical concern for the business in present era. Around 10% of the fundamental materials used in the chemical industry come from renewable resources, primarily plant materials [33,41]. In the past 10 years, much research has been conducted to transform renewable feedstock into fuels and chemicals. The majority of research is focused on the development of active and selective catalysts, with much less emphasis paid to their long-term stability [42]. Renewable carbon feedstocks such as biomass and CO2 are critical components of the future circular economy. Carbon dioxide is a readily available, low-cost and renewable carbon source for synthesis. Current interest in carbon dioxide valorization is focused on new, emerging technologies that can provide new opportunities to convert waste into profit [43]. Biomass, in particular as a highly functionalized feedstock, offers numerous options for translation into appealing platform chemicals [44]. It is now more important than ever to shift to renewable feedstocks for both material and fuel. Biomass, the substance obtainable from living organisms, is the world’s most important renewable feedstock for both material and energy. This comprises timber, crops, agricultural waste, food and so on. In the coming years, biomass attains maximum interest as renewable carbon source. Plants absorb CO2 during respiration, which is further released when these biomass-based products like biofuels are burned. As a result, biomass as a feedstock has the potential to generate CO2-neutral value chains and products. This chapter focuses on the utilization of renewable feedstock in the chemical industry and the formation of sustainable environment.

11.4 Requirements of renewable and sustainable feedstocks Currently, the growing renewability and sustainability in the modern era has reverberated through research and development in the field of chemical synthetic industry [45]. Practically applied 12 principles of green chemistry in chemical industry, Anastas and Zimmermann have reported 12 principles of green engineering as the motive of green

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chemistry [20,46]. Both catalogues are intended to serve as recommendations for the designing of more environmentally friendly synthesis, techniques, science and methodologies that may be applied to a variety of aspects of chemical research and production. However, there is no mention of biocatalysis’ significant promise for “green” chemical synthesis. Furthermore, a metrics of sustainability and “greenness” of a reaction process or medium have been established in the field of chemistry via green chemistry branches [47]. Trost’s Atom Economy notion was the first metric to be proposed, and it was quickly followed by Sheldon’s environmental (E) factor. According to the stoichiometric equation, the ratio of the desired product’s molar mass to the sum total of the molecular masses of all substances is generated. Later, the mass ratio of total waste to product exhibits process efficiency and environmental effect [48,49]. Chemical raw materials are presently manufactured almost entirely from fossil fuels like coal, petroleum and natural gas. The reduction of subterranean reserves, rising environmental dangers connected with production and the consequent imbalance of carbon in the ecosphere due to the use of these feedstocks make them less useful. Additionally, accessibility of various chemicals from these resources is limited firstly, resulting in sometimes long manufacturing methods as well as a very limiting product scenario of hydrocarbons. Moreover, functionalization via heteroatoms like nitrogen, oxygen, sulphur, halogens or phosphorous addition to avoid multistep cascade in chemical industry has led to enhanced demand with less energy consumption. Despite these flaws, there has been little motivation to alter the traditional route and irreversible chemical reaction carbon flow [50,51]. Biomass-derived sustainable starting materials exhibit higher degree of functionalization (heteroatoms and stereocenters) and permit high degree of multifunctionality in organic reaction. The nature-derived target molecules transform them into acceptable or desirable synthetic building route may be lower than for their petrochemical equivalents. Benefit of bio-based starting materials shows sustainable renewability and the ability to end the carbon cycle [52,53].

11.5 Renewable feedstock as catalytic system The catalytic materials designed from available natural resources and their effective use in organic transformation has become an expanding field of research in the catalysis sector over the last few decades. This green synthetic method is both cost-effective and environmentally friendly [54,55]. Catalysts are the crown jewels of chemical reactions. Chemical process industries make extensive use of them. According to a recent assessment, catalysis is used to make 95% of products (volume) and 70% of products (weight). In the chemical sector, over 80% catalytic reactions are demanding [56]. Since 1970, the demand for ecofriendly catalysts has been rising in order to save the environment with healthy living standards. The industrial area constantly focuses on the lookout for new catalysts that will minimize pollution, lower designing costs and are energy-efficient, harmless and reusable [57]. The present industrial demand for environmentally acceptable catalysts, catalytic compounds derived from natural resources has emerged as a viable alternative to traditional catalytic systems. Natural feedstock is used for the formation of different catalytic system that acts as sustainable renewable resource in catalytic industry. Natural feedstock

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material as productive catalysts, supporting system of catalyst or solvents can help to overcome a significant waste disposal problem while reducing the risk of contamination. Another advantage of this raw material is that synthetic procedures may become economically viable due to their natural abundance. The natural feedstocks as a source of catalysts act as part of a sustainable strategy that has aroused curiosity [58,59]. Catalysts obtained from natural feedstocks can improve the efficiency of chemical processes. This article discusses the organic transitions based on feedstock catalysts that have proved effective and successful, and economic and have environmental advantages of these systems over traditional catalytic systems [60,61]. Countless tons of garbage is produced every day throughout the world from a variety of industries, including agriculture, the food business, the pulp and fruit industry, as well as from dead plant and animal debris. Management of waste is a problem that affects everyone, and if it is not effectively handled, waste deposition can cause serious problems. The process of turning garbage into usable items has received a lot of attention lately. Waste materials are a source for both alternative renewable feedstock and catalyst production in the organic transformations. Catalysts based on waste materials have the potential to enhance the overall reaction rate and atom efficiency of both established and novel chemical methodology. Catalytic compounds created from various renewable resources are now an alternative to traditional catalyst systems due to the present need of the industrial sector for ecofriendly acceptable catalysts. The significant waste disposal issue and potential environmental damage can be significantly reduced by investing in feedstock as natural material for the creation of effective catalysts, catalytic supports or solvents. Because of this basic material’s abundant supply in nature, synthetic procedures may soon become commercially viable.

11.6 Different renewable resources used in organic synthetic chemistry 11.6.1 Using heterogeneous catalytic system Scientists studying catalysis have led the way in tackling issues including pollution and climate change with sustainable energy over the past 10 years [62]. Because of its outstanding ability to accelerate the reactions rate having low cost, easy conversion and selectivity of product, heterogeneous catalysis is at the core of catalysis science and powers many crucial industrial processes. Heterogeneous catalysts’ capacity to be recycled allows for environmentally friendly and sustainable manufacturing while also preventing the issue of secondary contamination. Around 80% of all synthetic products produced worldwide involve the use of heterogeneous catalytic system. Pillar industries like energy, environmental protection, precision chemical synthesis and bulk chemical production are examples of the rising demand for catalysts. Unquestionably, every breakthrough made in the field of heterogeneous catalysis has improved our daily lives and led to economic success for the major world economies [63]. High level global issues in energy and the environment are made possible by the heterogeneous catalysis community. According to science, the three fundamental steps, such as adsorption, desorption and surface reactions, connected to a solid support are what controls a successful heterogeneous catalytic reaction.

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As a result, the development of heterogeneous catalysis is inextricably linked to our understanding of surface and interface science, necessitating answers to three major big challenges: designing of catalyst and synthesis, in situ characterization and complexity of catalysis. To increase production follows environment friendly techniques, by using catalytic components on catalyst support requires efficient synthesis techniques and practices [64 67]. In order to inspire and stimulate the community, the heterogeneous catalysis specialist is a part of catalytic chemistry and it attempts to compile the most recent significant research in the field of synthetic organic chemistry [68]. Catalytic materials having selective static surface and bulky structures, with different structure function correlations of heterogeneous catalysts, have shown. Instead, they are dynamic objects that can alter their morphology or surface composition according to the local reaction conditions. Chemical characteristics also change as a result of such atomic-level modifications. As shown by various examples in Fig. 11.3, heterogeneous catalysts undergo a variety of structural modifications throughout reactions. Fig. 11.3A represents supported nanoparticles as heterogeneous catalytic system resulting in structural change with changing reaction conditions (e.g., pressure, temperature

FIGURE 11.3 Different mechanism of catalyst supported on solid surface. (A) Formulation of molecular species/supported metal complexes, (B) Sintering/redispersion, (C) Composite formation, (D) Morphological changes, (E) Surface alloying/Segregation, (F) Phase change, (G) Dissolution/leaching.

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and reaction medium etc.) around organometallic centres [69]. This type of reaction occurs in case of Rh catalyst in form of RhI(CO)2 for the methane partial oxidation reaction [70,71]. Fig. 11.3B represents the aggregation of nanoparticles, resulting due to decrease of the catalyst activity. This type of the aggregation creates problem in heterogeneous catalytic activity [72,73]. Fig. 11.3C represents composite formation with reactants. Fig. 11.3D describes strong support interaction via adhesion between particles and support leads to morphological changes. Depending on the reaction circumstances, bimetallic systems may exhibit segregation on the surface (Fig. 11.3E), which could result in the formation of cagelike structures, like PdRh-based nanoparticles catalytic system that exhibits segregation of Rh in NO oxidation process [74]. Another illustration is the complex based on intermetallic system like Pd2Ga for hydrogenation reaction, where surface breakdown occurs by oxygen impurities results in the catalyst active phase based on Ga-depleted Pd phase as Ga2O3 [75]. A common event in electro- and heterogeneous catalysis has phase change properties by oxidation process [76,77] or by the synthesis of carbides [78] (Fig. 11.3F). Such as in electrocatalysis process particularly under conditions, the material activity lost by metal particles dissolution (Fig. 11.3G) is experienced. The morphological changes of Cu/ZnO catalysts in the hydrogenation process of CO2 to methanol in CO/CO2/H2 reaction mixtures with varied redox potentials are a well-known example of how metal nanoparticles respond to fluctuations in the redox potential. These illustrations unequivocally demonstrate that structural alterations brought on by reaction strategy or by interactions with reactant particles, intermediates or desired products are crucial components of the identity of catalyst. Furthermore, due to the interesting relationship between structural alterations and catalytic activity, it is necessary to simultaneously gather spectroscopic data in order to correlate structural information. Therefore understanding the mechanism occurring at the surface of a catalyst and in the bulk material side are essential criteria for the designing of novel materials. To do this, appropriate modulate catalysts must be chosen and carefully studied using spectroscopic techniques. It can offer the details on electrical and structural effects, allowing for the creation of better catalyst candidates (Fig. 11.4) [79 81]. Heterogeneous catalytic system carried out isomerization, acetalization, hydrogenation, knoevenagel condensation, etc. [82 84].

FIGURE 11.4

Proposed mechanism of catalytic system (R 5 reactant, P 5 product).

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11.6.2 Using bioproducts The use of bioproducts based on plants, animals and dead organism plays crucial role in synthetic chemistry as renewable feedstocks for the synthesis of significant organic complex molecules and natural products. Another fascinating topic in chemical transformations that are applicable to the industry is the use of molecules that are bioderived as solvents. Utilizing both highly environmentally friendly technologies along with the use of renewable materials has a significant impact on production house of organic synthetic industries, which derived from finite resources, thereby rerouting the scope of increasing environmental sustainability. Banana peel ash, in addition to small amounts of various metallic and nonmetallic materials, contains considerable levels of sodium and potassium carbonates, potassium chlorides and oxide [85]. Pomegranate peel ash, the aqueous solution of pomegranate ash-assisted aryl halides Ullmann coupling reaction, was created by Lakshmidevi et al. Oac [86]. By using X-ray photoelectron spectroscopy and energydispersive X-ray (EDX) analysis, it was found that the water extract of pomegranate peel ash had significant amounts of chlorine, oxygen, calcium, magnesium, carbon and potassium. It has been reported via EDX study of rice straw ash and shown to include calcium, magnesium, sodium and potassium in rice-based ashes [87]. In a rice straw ash extract, Saikia and Borah discovered a sustained Dakin reaction of aryl aldehydes employing H2O2 as an external oxidant [88]. The benefits of this approach include the use of renewable resources, a wide range of catalyst, ambient settings, excellent yields around 85% 98% of the desired products in about 2 3 hours, and simple catalyst synthesis using rice straw ash extract. Papaya-based ashes, ion-exchange chromatographic and EDX examination of papaya bark ash revealed the existence of oxygen, copper, calcium, potassium, magnesium and sodium reported by Sarmah et al. [89]. Gohain et al. reported that EDX examination of papaya-based ash revealed the presence of significant amounts of sodium, calcium and potassium together with trace amounts of silica and magnesium [90]. The condensation Knoevenagel reaction of malononitrile and aryl aldehydes was carried out at 55 C in absolute ethanol using papaya stem ash. With 95.23% and 93.33% conversion utilizing CH3OH/oil (9:1) at 60 C for 3 hours, papaya ash (2wt.%) was also treated as sustainable like catalyst for the manufacture of biodiesel from Scenedesmus obliquus lipid and used oil. In the generation of biodiesel and the Knoevenagel reaction, the catalyst’s reusability was shown to be up to 5 6 cycles. According to Patil et al., the century plant (Agave Americana) leaf contains significant levels of magnesium, potassium, calcium, salt, zinc and phosphorus [91]. The Himalayan people also utilize the ash from these leaves, which has a basic composition, to wash their garments. Water hyacinth ash, the EDX study of the ash from the water hyacinth (Eichhornia crassipes), a very common aquatic weed, revealed the presence of significant amounts of potassium, magnesium, calcium and copper, by Sarmah et al. [92]. Natural or bio-based fibres such as flax, hemp, kenaf, sisal, pineapple leaf and henequen in combination with different natural polymers formed the desired products as renewable resources in the form of biocomposites. These composites are known to enhance performance in different fields. In the current century, the biodegradable nature of bio-based composites with lesser harmful effects opens more opportunities in various applications [93].

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11.6.3 Using natural products Natural products have long provided a source of inspiration for the creation of novel medicines, insecticides, herbicides and dyes, and complete synthesis is frequently the only means to get large amounts of such chemicals for prolonged research, much alone commercial endeavours [94,95]. This links total synthesis, natural product isolation and structural elucidation. New analytical techniques were created in response to the search for novel compounds with intriguing chemical or biological properties, and research chemists could be used to handle a target molecule. The more difficult the target molecules, on the other hand, the more work was put into developing novel procedures, technologies and theoretical ideas to enable their creation [96]. Formation of starting materials from natural resources comes under new generation of synthetic chemistry [35]. Biomass-derived feedstocks were never totally phased out, despite the move to petrochemicals as new starting materials. For many years, the main resource of building blocks and enantiopure catalysts was the chiral pool, made of amino acids, chiral terpenes, carbohydrates, and so on, found in nature [97]. This is based on the notion that people will understand the fundamental significance of synthetic green chemistry and that this field won’t be impacted by any future developments to economy, forming any feedstock adaptation to a higher level of sustainability essential. It follows that the application of natural renewable feedstocks in any organic synthesis process, which had vanished into obscurity more than a century ago, is being revived by academics. The primary goal of this study is to highlight synthetic procedures comprising sustainable chemistry practices and renewable carbon sources. The primary criteria for inclusion of total synthesis were the renewability of the starting materials and origin of the carbon atoms. The use of safe solvents, the use of catalytic procedures rather than the avoidance of protecting groups, stoichiometric transformations, and step efficiency or essential reactants are some other aspects of environmentally friendly chemistry that will be discussed. (1) Wood/lignin, as the greatest source of aromatics on earth and a significant component of lignocellulose, as wood-based biomass contains approximately 35% of lignin (Scheme 11.1A). It is an amorphous, cross-linking biopolymer that gives plants their structural integrity when combined with cellulose and hemicellulose. It acts as major alternative of petroleum resources. Lignin is a side waste product of paper manufacture process that may be made from wood pulp. It is created biochemically from three monomers of phenyl propanoid monolignol that merely vary in their oxidation. Vanillin, a platform chemical that has been found to be shown effective for the natural products synthesis, may be produced using a variety of methods for lignin depolymerization (oxidative, reductive, pyrolysis, hydrogenolysis and deoxygenation). (Scheme 11.1B). The goal of continuing research is to develop more sophisticated lignin valorization techniques that have the potential to transform agricultural or industrial waste made of wood into carbon-based renewable building blocks. A number of concerns need to be addressed, including lignin repolymerization, low efficiency, heterogeneity of structure, and difficulty in separation and purification process of product [98,99]. (2) Cellulose, dry biomass (up to 80%) of the plants, is composed of cellulose and hemicelluloses, which are the building blocks of plant cell walls.

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SCHEME 11.1

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(A) Monomer of lignin. (B) Lignin-derived compound used in natural product synthesis.

Although chemical compositions of hemicelluloses are quite diverse, cellulose only contains β (1-4) poly-D glucose, rendering it inedible to humans. It is a highly plentiful, renewable feedstock that shows promise as a source of chemical raw materials. Glucose obtained from cellulose and employed for the natural products synthesis [35,100]. (3) Chitin and chitosan form the cell walls of fungi, molluscan, and the exoskeletons of crustaceans and insects. This makes it the most prevalent biopolymer on earth that contains nitrogen and the second most common biopolymer after cellulose. Chitin has a linear polysaccharide structure similar to that of cellulose, but unlike cellulose, it is made up of 2acetamido-2-de-oxy D-glucopyranose monomer unit that are β (1-4) linked. The substance with a higher percentage of acetylated amino groups is known as chitin, whereas the compound with a lower quantity of N-acetylation is called chitosan. It is used for the manufacture of biofuel, functional compounds, raw materials, and for the applications in chemistry and pharmaceutical industry. The area of chitin valorization is still in its infancy, despite the fact that this is a particularly attractive feedstock due to its quantity, accessibility as a leftover from the food industry and special promise as a source of nitrogen-containing raw materials. [101 103]. (4) Fats and oils, either of plant or animal origin, appear as mono, di- and triglycerides with varying compositions of fatty acids depending on their origin. A perfect renewable feedstock for the manufacture of fuel and polymers as well as raw materials for chemical reaction in synthetic chemistry would be fats and oils. The bio-based fuels synthesis like biodiesel carried out by the use of fats and oils [104,105]. (5) Terpenes have long been used for the natural products synthesis because they are plentiful, renewable, affordable and adaptable chiral starting materials. They are hydrocarbon substances that involve one or more carbon-carbon double bonds with lower oxygen content. Since isoprene units with five carbon atoms are the primary precursors of

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all the terpenes, they may be separated into subgroups with names based on their carbon content [106]. Additionally, following green synthesis guidelines and methods throughout the entire sequence is not always practicable; in these cases, a traditional approach must be used. Both synthesis of pieces and construction using at least some biomass-derived raw materials are effective steps in the correct path.

11.7 Advantages of renewability factors in organic synthesis Synthetic chemists may be enticed to explore this sustainable technology for industrially important transformations of chemical, valorization of waste and energy-based applications by the described processes presented in this study, as well as the vast potential possibilities. Combining highly environmentally friendly technologies like the use of renewable materials has significant impact on reducing the need for volatile organic materials, which are based on depleting sources, thereby rerouting the scope of increased environmental sustainability and offering a remedy for the linear economy brought on by rapid urbanization, industrialization, population growth, and enhancing livelihoods. By reducing waste and providing inexpensive media, catalysts and bases, these processes can become very environmentally friendly processes. The researchers are concentrating on increased investigation of this approach in industrially or academically significant technology and chemical processes. Designing selective catalysts is crucial for the future of green chemistry since increased catalysis can decrease the number of stages in a particular process and hence lessen its environmental impact. A varied cross section of the scientific community must be involved in green chemistry in order to deliver within the requisite time frame [28]. By utilizing biorenewable ingredients in chemical synthesis and biodiesel generation, it is a sustainable method.

11.8 Future challenges and outlooks The use of ecofriendly reagents, solvents and methods in conjunction with renewable feedstocks as starting materials can result in processes that have little or no negative effects on our ecosystem. Therefore it is necessary to continually review current procedures, synthetic pathways and processes. Economic competitiveness has a significant role in determining whether or how fast those innovations will be deployed on a broad scale. Additionally, the pharmaceutical and agricultural chemical industries have started using bio-based raw materials. Leading examples of this finding include the creation of fenoprofen and norfenefrine from nut cashew shell liquid extracted cardanol as well as the creation of ranitidine and the insecticide prothrin from 5-(Chloromethyl)furfural (CMF). To enhance reusability cycle, more reactions are challenging and associated with future perspectives.

11.9 Conclusion The numerous and various challenges of organic synthesis impart a “feel” for chemical compound activity as well as a thorough comprehension of how to create more knowledge

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from the literature to address the several issues encountered along the way to the objective faced along the path to the goal. Synthetic methods and products were devised based on the components available from those sources. The selection of an ideal active ingredient to generate the desired chemistry in catalysis is known as catalyst design and synthesis. As per increasing public demand of synthetic chemicals as drugs, pesticides, cosmetics, households, etc., there is more interest of synthetic chemist and industry in ecofriendly ways. In the whole scenario, the renewability factor plays an important role for catalyst designing. This criterion not only depends on natural or bioproducts, it can also be heterogeneous catalyst that may be related to the reusability. The designing of new catalytic system having more efficiency and efficacy with short reaction time and lesser by-product formation may result in advanced methodology and technology in green chemistry.

References [1] Renewables and Green Chemistry, Green. Chem. 7 (2) (2005) 57. Available from: https://doi.org/10.1039/ b500769k. [2] N.V. Fedoroff, D.S. Battisti, R.N. Beachy, P.J.M. Cooper, D.A. Fischhoff, C.N. Hodges, et al., Radically rethinking agriculture for the 21st century, Science 327 (5967) (2010) 833 834. Available from: https://doi. org/10.1126/science.1186834. [3] K.C. Jones, P. de Voogt, Persistent organic pollutants (POPs): state of the science, Environ. Pollut. 100 (1 3) (1999) 209 221. Available from: https://doi.org/10.1016/S0269-7491(99)00098-6. [4] K. Ku¨mmerer, Antibiotics in the aquatic environment a review part II, Chemosphere 75 (4) (2009) 435 441. Available from: https://doi.org/10.1016/j.chemosphere.2008.12.006. [5] A. Agrwal, R. Saini, S. Bhandri, S. Verma, P. Srivastava, O. Prakash, Synthesis, ADMET, drug likeness and in silico activities of benzimidazole derivative, Mater. Today Proc. 67 (2022). Available from: https://doi.org/ 10.1016/j.matpr.2022.05.344. [6] S.A. Matlin, G. Mehta, H. Hopf, A. Krief, One-world chemistry and systems thinking, Nat. Chem. 8 (5) (2016) 393 398. Available from: https://doi.org/10.1038/nchem.2498. [7] B.S. Karki, S. Verma, A. Agrwal One Pot Three Component Organocatalyzed Synthesis Of Octahydroquinazolinones One Pot Three Component Organocatalyzed Synthesis Of Octahydroquinazolinones. 2017. [8] K.L. Pant, S. Verma, & V. Kasana L-Lactic Acid Catalyzed Facile One Pot Three Component Solventless Synthesis of α -Amino Phosphonates. 5(3), 2017, 12 16. [9] H.C. Erythropel, J.B. Zimmerman, T.M. de Winter, L. Petitjean, F. Melnikov, C.H. Lam, et al., The Green ChemisTREE: 20 years after taking root with the 12 principles, Green. Chem. 20 (9) (2018) 1929 1961. Available from: https://doi.org/10.1039/C8GC00482J. [10] A. Agrwal, A. Verma, N. Chantola, S. Verma, V. Kasana, Synthesis, molecular docking and extensive structure activity relationship of substituted DHP derivatives: a new class of herbicides, J. Environ. Sci. Health - Part. B Pesticides, Food Contaminants, Agric. Wastes 0 (0) (2022) 1 42. Available from: https://doi.org/10.1080/ 03601234.2022.2062188. [11] S. Verma, T. Das, V.K. Pandey, B. Verma, Nanoarchitectonics of GO/PANI/CoFe2O4 (Graphene Oxide/polyaniline/Cobalt Ferrite) based hybrid composite and its use in fabricating symmetric supercapacitor devices, J. Mol. Structure 1266 (2022) 133515. Available from: https://doi.org/10.1016/j.molstruc.2022.133515. [12] H. Derivatives, A. Hussain, S. Verma, S. Bhandari, V. Kasana. Calcium Chloride Dihydrate : An Efficient Catalyst for the Synthesis of Calcium Chloride Dihydrate : An Efficient Catalyst for the Synthesis of Hexahydropyrimidine Derivatives. 7(October), 2018, 926 940. [13] J.B. Zimmerman, P.T. Anastas, H.C. Erythropel, W. Leitner, Designing for a green chemistry future, Science 367 (6476) (2020) 397 400. Available from: https://doi.org/10.1126/science.aay3060. [14] S. Verma, T. Das, V.K. Pandey, B. Verma, Facile and scalable synthesis of reduced-graphene oxide using different green reducing agents and its characterizations, Diam. Relat. Mater. 129 (2022) 109361. Available from: https://doi.org/10.1016/j.diamond.2022.109361.

Green Chemistry Approaches to Environmental Sustainability

234

11. Use of renewable feedstocks for chemical synthesis

[15] J.H. Clark, Chemistry goes green, Nat. Chem. 1 (1) (2009) 12 13. Available from: https://doi.org/10.1038/ nchem.146. [16] J. Fahrenkamp-Uppenbrink, Chemistry goes green, Science 297 (5582) (2002) 798. Available from: https:// doi.org/10.1126/science.297.5582.798. [17] S. Verma, V.K. Pandey, B. Verma, Synthesis and supercapacitor performance studies of graphene oxide based ternary composite, Mater. Technol. (2022) 1 17. Available from: https://doi.org/10.1080/ 10667857.2022.2086767. [18] J.O. Metzger, Green Chemistry. Designing Chemistry for the Environment. Herausgegeben von P. T. Anastas und T. S. Williamson. American Chemical Society, Wahington, D. C., 1996. 251 S., geb. 89.95 d.-ISBN 0 84123399-3, Angew. Chem. 109 (7) (1997) 812 813. Available from: https://doi.org/10.1002/ANGE.19971090736. [19] Z. Wang, Green chemistry : recent advances in developing catalytic processes in environmentally-benign solvent systems, Front. Chem. (2008) 1 43. [20] P.T. Anastas, J.B. Zimmerman, Design through the 12 principles of green engineering, IEEE Eng. Manag. Rev. 35 (3) (2007) 16. Available from: https://doi.org/10.1109/EMR.2007.4296421. [21] P.T. Anastas, J.C. Warner, Green Chemistry : Theory and Practice, Oxford University Press, 1998. [22] P. Anastas, N. Eghbali, Green chemistry: principles and practice, Chem. Soc. Rev. 39 (1) (2010) 301 312. Available from: https://doi.org/10.1039/b918763b. [23] S.L.Y. Tang, R.L. Smith, M. Poliakoff, Principles of green chemistry: PRODUCTIVELY, Green. Chem. 7 (11) (2005) 761 762. Available from: https://doi.org/10.1039/B513020B. [24] S. Verma, V. Kasana, Development of novel herbicidal ionic liquids, Int. Res. J. Pure Appl. Chem. 15 (1) (2017) 1 8. Available from: https://doi.org/10.9734/irjpac/2017/36792. [25] T. Deligeorgiev, N. Gadjev, A. Vasilev, S. Kaloyanova, J.J. Vaquero Green Chemistry in Organic Synthesis Green Chemistry in Organic Synthesis. 2010. [26] M.M. Kirchhoff Origins, Current Status, and Future Challenges of Green. 35(9), 2002, 686 694. [27] M. Koel, M. Kaljurand Application of the Principles of Green Chemistry in Analytical Chemistry*. 78(11), 2006, 1993 2002. Available from: https://doi.org/10.1351/pac200678111993. [28] M. Poliakoff, J.M. Fitzpatrick, T.R. Farren, P.T. Anastas, Chemistry: Sci. Change of 297 (2002) 807 810. AUGUST. [29] D. Ravelli, D. Dondi, A. Albini. Photocatalysis. A Multi-Faceted Concept for Green Chemistry. 2011, 1999 2011. Available from: https://doi.org/10.1039/b714786b. [30] R.A. Sheldon. Cutting-Edge Research for a Greener Sustainable Future the E Factor: Fifteen Years On. 9(12) 2007. https://doi.org/10.1039/b713736m. [31] L. Singh, S. Ravichandran Green Chemistry: The Future Pillars Green Chemistry: The Future Pillars. 2022, 4 7. [32] M. Tobiszewski Green Chemistry Metrics with Special Reference to Green Analytical Chemistry. 2015, 10928 10946. Available from: https://doi.org/10.3390/molecules200610928 [33] C. Raston, Renewables and green chemistry, Green. Chem. 7 (2) (2005) 57. Available from: https://doi.org/ 10.1039/B500769K. [34] Adv Synth Catal (n.d.). Available from: https://doi.org/10.1002/adsc.202000634. [35] J. Groß, T. Opatz Natural Product Reports Making Natural Products from Renewable Feedstocks: Back to the Roots? 2020, 380 424. Available from: https://doi.org/10.1039/c9np00040b. [36] K.K. Bansal, J.M. Rosenholm Synthetic Polymers From Renewable Feedstocks: An Alternative to Fossil-Based Materials in Biomedical Applications, 2020. [37] A. Al-jumaili, A. Kumar, K. Bazaka, M.V. Jacob Plant Secondary Metabolite-Derived Polymers : A Potential Approach to Develop Antimicrobial Films. 2018. Available from: https://doi.org/10.3390/polym10050515. [38] S. Spierling, E. Knu¨pffer, H. Behnsen, M. Mudersbach, H. Krieg, S. Springer, et al., Bio-based plastics - a review of environmental, social and economic impact assessments, J. Clean. Prod. 185 (2018) 476 491. Available from: https://doi.org/10.1016/j.jclepro.2018.03.014. [39] G. Lligadas, J.C. Ronda, M. Galia`, V. Ca´diz, Oleic and undecylenic acids as renewable feedstocks in the synthesis of polyols and polyurethanes, Polymers 2 (4) (2010) 440 453. Available from: https://doi.org/ 10.3390/POLYM2040440. [40] S. Verma, B. Verma. Graphene-Based Nanomaterial for Supercapacitor Application, 2022, pp. 221 244. Available from: https://doi.org/10.1007/978-3-030-99302-3_11.

Green Chemistry Approaches to Environmental Sustainability

References

235

[41] J.C.J. Bart, E. Gucciardi, S. Cavallaro, Renewable lubricants, Biolubricants, Woodhead Publishing, 2013, pp. 1 9. Available from: https://doi.org/10.1533/9780857096326.1. [42] J.P. Lange, Renewable feedstocks: the problem of catalyst deactivation and its mitigation, Angew. Chem. Int. Ed. 54 (45) (2015) 13186 13197. Available from: https://doi.org/10.1002/ANIE.201503595. [43] B. Grignard, S. Gennen, C. Je´roˆme, A.W. Kleij, C. Detrembleur, Advances in the use of CO2 as a renewable feedstock for the synthesis of polymers, Chem. Soc. Rev. 48 (16) (2019) 4466 4514. Available from: https:// doi.org/10.1039/C9CS00047J. [44] R. Palkovits, I. Delidovich, Efficient utilization of renewable feedstocks: the role of catalysis and process design, Philos. Trans. R. Soc. A: Mathematical, Phys. Eng. Sci. 376 (2110) (2018). Available from: https://doi. org/10.1098/RSTA.2017.0064. [45] M. Eissen, J.O. Metzger, E. Schmidt, U. Schneidewind, 10 years after rio-concepts on the contribution of chemistry to a sustainable development, Angew. Chem. Int. Ed. 41 (3) (2002) 414 436. Available from: https://doi.org/10.1002/1521-3773(20020201)41:3 , 414::AID-ANIE414 . 3.0.CO;2-N. [46] G. Engineering The European Information Society: Taking Geoinformation Science One Step Further. Lecture Notes in Geoinformation and Cartography, 2008. [47] R.A. Sheldon, Metrics of green chemistry and sustainability: past, present, and future, ACS Sustain. Chem. Eng. 6 (1) (2018) 32 48. Available from: https://doi.org/10.1021/acssuschemeng.7b03505. [48] R.A. Sheldon, The E factor: fifteen years on, Green. Chem. 9 (12) (2007) 1273. Available from: https://doi. org/10.1039/b713736m. [49] B. Trost, The atom economy—a search for synthetic efficiency, Science 254 (5037) (1991) 1471 1477. Available from: https://doi.org/10.1126/science.1962206. [50] N. Brun, P. Hesemann, D. Esposito Chemical Science Expanding the Biomass Derived Chemical Space. 2017, 4724 4738. Available from: https://doi.org/10.1039/c7sc00936d. [51] A. Corma, S. Iborra, A. Velty Chemical Routes for the Transformation of Biomass into Chemicals, 2007. [52] H. Yang, N. Yan Sustainable Routes for the Synthesis of Renewable Heteroatom- Containing Chemicals, 2018. Available from: https://doi.org/10.1021/acssuschemeng.8b00612. [53] A. Nzihou Toward the Valorization of Waste and Biomass. February, 2010, 3 7. Available from: https://doi.org/ 10.1007/s12649-010-9014-x. [54] S. Verma, V. Kasana Tetrabutylammonium Prolinate : A Catalytic Moiety for the Synthesis of One Pot Five Component Synthesis of Octahydroquinazolinone-1, 3-Dicarbaldehyde Tetrabutylammonium prolinate: A Catalytic Moiety for the Synthesis of One Pot Five Component Synthesis. 2017. [55] H. Duan, D. Wang, Y. Li, Green chemistry for nanoparticle synthesis, Chem. Soc. Rev. 44 (16) (2015) 5778 5792. Available from: https://doi.org/10.1039/C4CS00363B. [56] R.K. Neff, D.E. Frantz, Recent advances in the catalytic syntheses of allenes: a critical assessment, ACS Catal. 4 (2) (2014) 519 528. Available from: https://doi.org/10.1021/cs401007m. [57] V. Polshettiwar, R.S. Varma, Green chemistry by nano-catalysis, Green. Chem. 12 (5) (2010) 743. Available from: https://doi.org/10.1039/b921171c. [58] J. Hancso´k, T. Kasza, S. Kova´cs, P. Solymosi, A. Hollo´, Production of bioparaffins by the catalytic hydrogenation of natural triglycerides, J. Clean. Prod. 34 (2012) 76 81. Available from: https://doi.org/10.1016/j. jclepro.2012.01.036. [59] Y. Kim, C.-J. Li, Perspectives on green synthesis and catalysis, Green. Synth. Catal. 1 (1) (2020) 1 11. Available from: https://doi.org/10.1016/j.gresc.2020.06.002. [60] B.C. Gates, G.W. Huber, C.L. Marshall, P.N. Ross, J. Siirola, Y. Wang, Catalysts for emerging energy applications, MRS Bull. 33 (4) (2008) 429 435. Available from: https://doi.org/10.1557/mrs2008.85. [61] U.P. Patil, S.S. Patil, Natural feedstock in catalysis: a sustainable route towards organic transformations, Top. Curr. Chem. 379 (5) (2021) 36. Available from: https://doi.org/10.1007/s41061-021-00346-6. [62] S. Verma, V.K. Pandey, B. Verma, Facile synthesis of graphene oxide-polyaniline-copper cobaltite (GO/ PANI/CuCo2O4) hybrid nanocomposite for supercapacitor applications, Synthetic Metals, 286, 2022March. Available from: https://doi.org/10.1016/j.synthmet.2022.117036. [63] S. Verma, & V. Kasana One Pot Synthesis of β -Phosphonomalonates at Room Temperature Using Tetrabutylammonium Bromide as an Efficient Catalyst One Pot Synthesis of β -Phosphonomalonates at Room Temperature Using Tetrabutylammonium Bromide as an Efficient Catalyst. 2017b.

Green Chemistry Approaches to Environmental Sustainability

236

11. Use of renewable feedstocks for chemical synthesis

[64] A.T. Adeleye, A.A. Akande, C.K. Odoh, M. Philip, T.T. Fidelis, P.I. Amos, et al., Efficient synthesis of biobased activated carbon (AC) for catalytic systems: a green and sustainable approach, J. Ind. Eng. Chem. 96 (2021) 59 75. Available from: https://doi.org/10.1016/j.jiec.2021.01.044. [65] R. Klaewkla, M. Arend, W. F A Review of Mass Transfer Controlling the Reaction Rate in Heterogeneous Catalytic Systems. Mass Transfer - Advanced Aspects, 2011. https://doi.org/10.5772/22962. [66] J. Mahatthananchai, A.M. Dumas, J.W. Bode, Catalytic selective synthesis, Angew. Chem. Int. Ed. 51 (44) (2012) 10954 10990. Available from: https://doi.org/10.1002/anie.201201787. [67] M. Sankar, N. Dimitratos, P.J. Miedziak, P.P. Wells, C.J. Kiely, G.J. Hutchings, Designing bimetallic catalysts for a green and sustainable future, Chem. Soc. Rev. 41 (24) (2012) 8099. Available from: https://doi.org/ 10.1039/c2cs35296f. [68] X. Hu, A.C. K. Yip Heterogeneous Catalysis: Enabling a Sustainable Future. 1(March), 2021, 1 3. Available from: https://doi.org/10.3389/fctls.2021.667675. [69] L. Liu, A. Corma, Metal catalysts for heterogeneous catalysis: from single atoms to nanoclusters and nanoparticles, Chem. Rev. 118 (10) (2018) 4981 5079. Available from: https://doi.org/10.1021/acs.chemrev.7b00776. [70] L. Basini, A. Guarinoni, A. Aragno, Molecular and temperature aspects in catalytic partial oxidation of methane, J. Catal. 190 (2) (2000) 284 295. Available from: https://doi.org/10.1006/jcat.1999.2745. [71] J.-D. Grunwaldt, L. Basini, B.S. Clausen, In situ EXAFS study of Rh/Al2O3 catalysts for catalytic partial oxidation of methane, J. Catal. 200 (2) (2001) 321 329. Available from: https://doi.org/10.1006/jcat.2001.3211. [72] J.-D. Grunwaldt, A. Molenbroek, N.-Y. Topsøe, H. Topsøe, B. Clausen, In situ investigations of structural changes in Cu/ZnO catalysts, J. Catal. 194 (2) (2000) 452 460. Available from: https://doi.org/10.1006/ jcat.2000.2930. [73] Y. Nishihata, J. Mizuki, T. Akao, H. Tanaka, M. Uenishi, M. Kimura, et al., Self-regeneration of a Pdperovskite catalyst for automotive emissions control, Nature 418 (6894) (2002) 164 167. Available from: https://doi.org/10.1038/nature00893. [74] F. Tao, M.E. Grass, Y. Zhang, D.R. Butcher, J.R. Renzas, Z. Liu, et al., Reaction-driven restructuring of Rh-Pd and Pt-Pd core-shell nanoparticles, Science 322 (5903) (2008) 932 934. Available from: https://doi.org/ 10.1126/science.1164170. [75] A. Ota, J. Kro¨hnert, G. Weinberg, I. Kasatkin, E.L. Kunkes, D. Ferri, et al., Dynamic surface processes of nanostructured Pd 2 Ga catalysts derived from hydrotalcite-like precursors, ACS Catal. 4 (6) (2014) 2048 2059. Available from: https://doi.org/10.1021/cs500465r. [76] E. Lira, L.R. Merte, F. Behafarid, L.K. Ono, L. Zhang, B. Roldan Cuenya, Role and evolution of nanoparticle structure and chemical state during the oxidation of NO over size- and shape-controlled Pt/γ-Al 2 O 3 catalysts under operando conditions, ACS Catal. 4 (6) (2014) 1875 1884. Available from: https://doi.org/ 10.1021/cs500137r. [77] C.J. Pelliccione, E.V. Timofeeva, J.P. Katsoudas, C.U. Segre, In situ Ru K-edge X-ray absorption spectroscopy study of methanol oxidation mechanisms on model submonolayer Ru on Pt nanoparticle electrocatalyst, J. Phys. Chem. C. 117 (37) (2013) 18904 18912. Available from: https://doi.org/10.1021/jp404342z. [78] M.W. Tew, M. Nachtegaal, M. Janousch, T. Huthwelker, J.A. van Bokhoven, The irreversible formation of palladium carbide during hydrogenation of 1-pentyne over silica-supported palladium nanoparticles: in situ Pd K and L3 edge XAS, Phys. Chem. Chem. Phys. 14 (16) (2012) 5761. Available from: https://doi.org/ 10.1039/c2cp24068h. [79] A. Vojvodic, J.K. Nørskov, New design paradigm for heterogeneous catalysts, Natl Sci. Rev. 2 (2) (2015) 140 143. Available from: https://doi.org/10.1093/nsr/nwv023. [80] K.F. Kalz, R. Kraehnert, M. Dvoyashkin, R. Dittmeyer. Future Challenges in Heterogeneous Catalysis : Understanding Catalysts under Dynamic Reaction Conditions. 2017, 17 29. Available from: https://doi.org/10.1002/cctc.201600996. [81] J.K. Nørskov, T. Bligaard, J. Rossmeisl, C.H. Christensen, Towards the computational design of solid catalysts, Nat. Chem. 1 (1) (2009) 37 46. Available from: https://doi.org/10.1038/nchem.121. [82] X. Zhao, L. Wei, S. Cheng, J. Julson Review of Heterogeneous Catalysts for Catalytically Upgrading Vegetable Oils into Hydrocarbon Biofuels, 2017. Available from: https://doi.org/10.3390/catal7030083. [83] H. Hartati, P.B.D. Firda, H. Bahruji, M.B. Bakar, Review on heterogeneous catalysts for the synthesis of perfumery chemicals via isomerization, acetalization and hydrogenation, Flavour. Fragr. J. 36 (5) (2021) 509 525. Available from: https://doi.org/10.1002/ffj.3671.

Green Chemistry Approaches to Environmental Sustainability

References

237

[84] J.N. Appaturi, R. Ratti, L. Phoon Catalysts for Knoevenagel condensation. 2021, pp. 4445 4469. Available from: https://doi.org/10.1039/d1dt00456e. [85] K. Venkateswarlu, Ashes from organic waste as reagents in synthetic chemistry : a review, Environ. Chem. Lett. 19 (Issue 5) (2021)Springer International Publishing. Available from: https://doi.org/10.1007/s10311021-01253-4. [86] P. Oac WEPA: A Bio-Derived Medium for Added Base, Π-Acid and Ligand Free Ullmann Coupling of Aryl Halides Using Pd(OAc)2. 2018, 12333 12336. Available from: https://doi.org/10.1039/c8cc06940a. [87] A. Mahanta, M. Mondal, A. Jyoti, U. Bora, An improved Suzuki Miyaura cross-coupling reaction with the aid of in situ generated PdNPs : evidence for enhancing effect with biphasic system, Tetrahedron Lett. 57 (29) (2016) 3091 3095. Available from: https://doi.org/10.1016/j.tetlet.2016.05.098. [88] B. Saikia, P. Borah RSC Advances. 2015, pp. 105583 105586. Available from: https://doi.org/10.1039/c5ra20133k. [89] M. Sarmah, A. Dewan, M. Mondal, A.J. Thakur, U. Bora RSC Advances Ash and Its Implications as an In Situ Base in the Ligand-Free Recyclable Suzuki Miyaura Coupling Reaction. 2016, pp. 28981 28985. Available from: https://doi.org/10.1039/c6ra00454g. [90] M. Gohain, K. Laskar, A. Kumar, N. Daimary, Carica papaya stem : A source of versatile heterogeneous catalyst for biodiesel production and C e C bond formation, Renew. Energy 147 (2020) 541 555. Available from: https://doi.org/10.1016/j.renene.2019.09.016. [91] U.P. Patil An Eco-friendly Catalytic System for One-pot Multicomponent Synthesis of Diverse and Densely Functionalized Pyranopyrazole and Benzochromene Derivatives. 2019, Available from: https://doi.org/10.1002/ jhet.3564. [92] M. Sarmah, A. Dewan, A.J. Thakur, U. Bora Extraction of Base from Eichhornia crassipes and Its Implication in Palladium-Catalyzed Suzuki Cross-Coupling Reaction. 2017, pp. 7091 7095. Available from: https://doi.org/ 10.1002/slct.201701057. [93] A.K. Mohanty, M. Misra, L.T. Drzal Sustainable Bio-Composites from Renewable Resources: Opportunities and Challenges in the Green Materials World. 10, 2020, 19 26. [94] K.C. Morrison, P.J. Hergenrother Of Complex and Diverse Compounds. 2014, pp. 6 14. Available from: https://doi.org/10.1039/c3np70063a. [95] D.J. Newman, G.M. Cragg, K.M. Snader Natural Products as Sources of New Drugs over the Period 1981 2002. 2003, pp. 1022 1037. [96] P.S. Baran Themed Issue: Natural Product Synthesis, 2014. 31(4). Available from: https://doi.org/10.1039/ c3np70090a. [97] Z.G. Brill, M.L. Condakes, C.P. Ting, T.J. Maimone Navigating the Chiral Pool in the Total Synthesis of Complex Terpene Natural Products. 2017, Available from: https://doi.org/10.1021/acs.chemrev.6b00834. [98] J. Zakzeski, P.C. A. Bruijnincx, A.L. Jongerius, B.M. Weckhuysen The Catalytic Valorization of Lignin for the Production of Renewable Chemicals. 2010, pp. 3552 3599. [99] M. Carrier, A. Loppinet-serani, D. Denux, J. Lasnier Thermogravimetric Analysis as a New Method to Determine the Lignocellulosic Composition of Biomass. 2010, 5, pp. 1 10. Available from: https://doi.org/10.1016/j. biombioe.2010.08.067. ˜ , S. Hosokawa Total Syntheses of Bioactive Natural Products from Carbohydrates [100] K. Tatsuta, S. Hosokawa, K.T. A Total Syntheses of Bioactive Natural Products from Carbohydrates. 2006, 6996. Available from: https://doi.org/ 10.1016/j.stam.2006.05.001. [101] X. Chen, Y. Gao, L. Wang, H. Chen, N. Yan Effect of Treatment Methods on Chitin Structure and Its Transformation into Nitrogen-Containing Chemicals. 2015, pp. 1565 1572. Available from: https://doi.org/ 10.1002/cplu.201500326. [102] M.J. Hu ScienceDirect Shell biorefinery : A comprehensive introduction. 3, 2018, pp. 318 327. Available from: https://doi.org/10.1016/j.gee.2018.07.007. [103] P.P. M. K Don’t Waste Seafood Waste, n.d., pp. 5 7. [104] H. Baumann, M. Biihler, H. Fochem, F. Hirsinger, H. Zoebelein, B.H. Baumann, et al., Int. Ed. Engl. 27 (1) (1998) 41 62. [105] H. Bra¨nnstro¨m, H. Kumar Current and Potential Biofuel Production from Plant Oils. 2018, pp. 592 613. [106] W. Schwab, C. Fuchs, F. Huang,Review Article Transformation of Terpenes into Fine Chemicals. 2013, pp. 3 8. Available from: https://doi.org/10.1002/ejlt.201200157.

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C H A P T E R

12 A green approach: living nanofactories Vandana Singh1 and Babita2 1

Department of Microbiology, School of Allied Health Sciences, Sharda University, Gr. Noida, Uttar Pradesh, India 2Department of Pharmacology, School of Allied Health Sciences, Sharda University, Gr. Noida, Uttar Pradesh, India

12.1 Introduction A unique idea and branch of nanotechnology known as nanobiotechnology has attracted worldwide interest. The best strategy for minimizing the consequences of nanomaterial production and enhancing its application while lowering the risks of problems rose on is green nanotechnology [1]. Fig. 12.1 shows the biological synthesis of nanoparticles (NPs). Green nanotechnology involves the utilization of NPs, which are small in size and a huge surface area compared to their counter and bulk forms and above all produced through living nanofactories. Chemical, optical and thermal processes are few of the attributes that nanomaterials possess. Nanomaterials have been thought of as a viable substitute in response for implementation in a wide variety of biological applications. Researchers have been looking at a variety of methods, including chemical, physical and biological ones, to create these NPs, but the biological technique—also known as green synthesis technology—has proven to be the most efficient, economical and environmentally benign [2,3]. The production of NPs via green synthesis techniques employs biological agents such as human cells, viruses, bacterial strains, fungus, algae, plants extracts and yeast. Biological agents (bacteria, fungi, plants and viruses) also do not obstruct the usage of synthesized NPs and are non-pathogenic in nature too [4]. This chapter mainly emphasizes on the different method for “green” synthesis of nanomaterial and related elements which will benefit scientists conducting research in this field and also serve as a helpful resource for readers generally interested in the topic. NPs are commonly have a lots of uses in biological, medicinal, environmental and engineering applications due to their characteristics known as biocompatibility, antibacterial

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12. A green approach: living nanofactories

Green synthesis of nanoparticles by biological factories and their applications.

action, anti-inflammatory properties, efficient drug delivery, bioavailability, bioactivity, tumour targeting and easy biological absorptions [5]. These potential of NPs have attracted a lot of attention and also being explored in a variety of industries, including medicine, material science/chemistry, IT (information technology), agricultural sciences, pharmaceutical industries, optical industries, electronics, environment, sensors, etc. Copper, silver, zinc, iron, titanium, magnesium, cerium and zirconium oxide are just a few of the metallic NPs that belong to this category [6]. Living nanofactories are a green approach to manufacturing and production that utilizes tiny, self-sustaining, biological machines to create materials and products. These nanofactories operate at the molecular level, utilizing organic, renewable resources and biodegradable materials to create products without the need for harmful chemicals or energy-intensive processes. The benefits of living nanofactories include the following: 1. Reduced environmental impact: By using renewable resources and biodegradable materials, living nanofactories minimize the environmental impact of production processes. 2. Increased efficiency: Because they operate at the molecular level, living nanofactories can create products faster and more efficiently than traditional manufacturing methods.

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3. Customization: Because living nanofactories can be programmed to produce specific materials and products, they offer the ability to create customized products on demand. 4. Cost savings: By utilizing renewable resources and biodegradable materials, living nanofactories can reduce the cost of production compared to traditional manufacturing methods. Overall, living nanofactories offer a sustainable and ecofriendly approach to production that can help reduce our reliance on harmful chemicals and energy-intensive processes. NPs have attracted a lot of attention due to their remarkable properties, which are regulated by the geometry of their structural shape. Both chemical and physical methods have been utilized in numerous studies to create NPs and among all the common procedure is bottom up and top down approach. In a bottom up technique, the smaller components are broken apart, whereas a -down approach breaks a large component into nano size. Fig. 12.2 depicts the “top down” and “bottom up” approaches of synthesizing NPs. In top down method, such as sputtering, lithography, mechanical (such as grinding, milling, etc.), chemical-based etching, laser-based ablation, thermal evaporation and phototrophic reduction, bulk materials are broken down into tiny particles to create NPs. Cost, shape and size are the major benefits of a top down strategy. The monodisperse NPs produced by this technology have higher yields and consistency in terms of shape, geometry and size. Additionally, it also increases the effectiveness of medication encapsulation and stability. Top down techniques are important for building macroscopic links and long-range ordered systems. In contrast, a major hitch of the top down technique is the incompleteness of nanosurface structure [7].

FIGURE 12.2 The “top-down” and “bottom-up” approaches of synthesizing nanoparticles.

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Wet-chemical methodologies (such as chemical-based oxidation/reduction of metal ions), co-precipitation, solid-gel chemistry, microemulsion, hydrothermal, chemical vapour deposition, radiation-induced, pyrolysis, electrodeposition and solvothermal methods are part of bottom up approach. Bottom up process of synthesis is the process of creating NPs from smaller particles such as molecules and atoms. The bottom up strategies often rely on atomic change and molecule condensation [8]. These, however, incur from the utilization of by-products that take a long time to react, more expensive, are eco-toxic and potentially hazardous [9]. The majority of chemical processes employ hazardous reducing agents like sodium borohydride (NaBH4), ethylene glycol, sodium citrate, hydrazine, etc.; however, these processes produce particles with poor size and distribution, necessitating the use of additional capping agents like dendrimers, polymers and surfactants (e.g., sodium-dodecyl-sulfate and cetyl-trimethoxysilane). When the stabilizing and reducing agent is removed from the surface of the NP, it is possible that the active site of the particle will be limited, resulting in a reduced surface area and lower product reactivity [10]. Thermal annealing is also required to achieve good crystalline sample. The high cost and toxic qualities of this synthetic approach may restrict its use on a large scale. Additionally, the products produced by this method have poor efficiency. Metal atoms form clusters and finally NPs during the environmentally friendly process of biosynthesis, which works from the bottom up method. Chemical reduction is linked to the idea of biosynthetics although environmentally friendly biological materials are used to make NPs instead of expensive and dangerous chemicals. Researchers used adverse reaction monitoring to discriminate between chemical-based degradation of NPs produced using green methodologies and a conventional wet-chemistry method [9]. In chemical-based production, factors such as temperature, incubation duration and pH can affect reactions and alter the structural characteristics of NPs, for instance symmetry, size, shape, forms, etc. [10]. Green NPs are naturally safe and have wide range of biomedical applications, particularly in the field of oncology, as their cytotoxicity and phytotoxicity were measured much lower than the chemically synthesized NPs. Because of these reasons and growing recognition of its significance, biosynthesis has been hailed as a promising green alternative that appears to offer the best methodology or results among the various green chemistry approaches [9]. The most known NPs synthesizing biological agents or green nanofactories found in nature are plants, viruses, algae, human cells, fungi, yeast and bacterial cells. The constitution of living entities has a considerable impact on the structure and appearance of synthesized NPs. A useful paradigm for the creation of NPs is the fascinating range of NPs (which vary in forms and sizes) that emerged from the diversity of biological entities [11]. Biological agent such as Lonicera japonica flower extract was explored for the production of quasi-spherical, face-centred cubic, hexagonal and trilateral, gold (Au) NPs of a size 8.01 nm. Seaweeds and algal cells are among two most recently discovered biologicalreducing agents that are regarded to have tremendous promise for the treatment of colorectal cancer. Protein concentrations and the concentration of platinum (Pt) salts both affect the shape and size of Pt NPs produced by biogenesis. Some researchers also explored fungi as biological agent and a promising “scale-up” agent used in production of Pt-NPs [10]. Similar to that, NPs were also organically created by employing plant extracts that contained phytochemical components that serve as capping agents. Studies offer a multitude of benefits and show the diversity of biological entities that exist naturally. NP

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synthesis is possible by changing variables including temperature, plant extracts, acidity, boiling time, extract ageing effects and plant extracts. Due to the abundance of biomolecules, affordability, stability, lack of harmful chemicals and ease of use, biological synthesis is the best method [12]. Furthermore, researchers also employed viruses to create synthetic nanocrystals such as silicon dioxide, cadmium sulphide, zinc sulphide, ferrous oxide, etc. The use of whole viruses to synthesize nanomaterials has been studied from the past few decades. The outer layer of capsid protein of the viruses aids in the formation of NPs by forming a highly reactive metallic ion-binding surface [13]. For example, the outer cell surface of the tobacco mosaic virus (TMV) has 2130 capsid proteins with capsomers. These peptides act as connectors for notches to deposit or build 3-D vessels which help in the formation of NPs and used for a variety of medical applications [14]. The creation of NPs from various biological sources is an emerging field that has researchers’ interest in the field of green chemistry. Due to economic and environmental toxicity concerns, the chemical and physical methods of synthesizing NPs are gradually making way for environmentally benign biological alternatives. As an alternative to the traditional physical and chemical methods of synthesising NPs, living organisms or their biomass may be used [15]. The biological production of NPs also enables its simple centrifugation-based scale-up or separation from the reaction environment. In addition, compared to chemically synthesised NPs, biologically produced NPs with a covering of biological molecules on their surface are more biocompatible [16].

12.2 Biological nanofactories Many resources have been explored for the production of NPs employing a variety of living organisms. These living things can act as biological nanofactories to manufacture nanomaterials because of their widespread dispersion along ecological limits, ease of accessibility, safety in handling and existence of a large variety of metabolites. Moreover, size and form of NPs are influenced by the makeup of biological substances, their quantities and the type of organic reducing agents present. Additionally, factors in the growing media, including as pH, salt concentration, temperature and exposure period, have a significant impact on the size of NPs [10]. These biological agents possess reducing agents that act on the metal precursors to form required NPs with desired shape and size. Moreover, the biological agents also have capping and stabilizing chemicals, which are necessary to stop the growth and hinder the aggregation/agglomeration process. Due to the enormous potential of microbes and plants as sources, biological synthesis can be used as an environmentally friendly way in place of conventional methods to create NPs. Following are the green nanofactories for the synthesis of NPs [16].

12.2.1 Bacteria Prokaryotes have many benefits over eukaryotes for the synthesis of NPs, including high level growth rate and innate mechanisms to combat with tremendous lethality of heavy metals that comprises the majority of these NPs. These mechanisms consist of methods like

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metal nanoarrays that are harmless or less toxic and are produced through reduction and/or precipitation [17]. In order to produce metallic NPs, microorganisms have been widely used due to its relative accessibility of manipulation. Bacterial strains and their species have been used widely in industrial processes such as bioleaching, genetic alteration and environmental remediation. Bacteria are one of the interesting possibilities for the biomanufacture of NPs because they can reduce metal ions easily [18]. Numerous studies have been illustrated on the synthesis of metal and metal-oxide NPs using prokaryotes and actinomycetes [19]. The modification of solubility and toxicity via biosorption, bioaccumulation, extracellular intercalation, metals precipitation and redox reaction are among some of the potential mechanisms by which bacteria produce desired NPs [12]. Microbes are also explored as a biocatalyst for synthesizing inorganic components, bioprocess for mineralization or a direct contributor to the manufacturing of nanomaterials. Bacteria in broth medium can produce extracellular or intracellular nanomaterials during an incubation phase [20]. Bacterial biosynthesis of NPs, which is a by-product of this procedure, is a practical, adaptable and acceptable choice for high production. It is still largely unknown how biosynthetic metal oxides at the nanoscale are produced. The main cause of this is that most of the biosynthesis-related enzymes are unexplored. Although it has been demonstrated that biological synthesis can produce harmless metal oxides, controlling crystal size, shape and crystallinity in this process needs proper cell culture [21]. NPs made by bacteria have been used because they are relatively simple to manage. Researchers have explored and also stated the possibility for NPs synthesis in both Gram-negative and positive bacteria [22]. The examples of bacterial strains employed in the synthesis of these NPs are Pseudomonas proteolytica, Bacillus indicus, B. cecembensis, B. amyloliquefaciens, Phaeocystis antarctica, B. cecem, Geobacter spp., Enterobacter cloacae, Klebsiella pneumoniae, Morganella sp., Pseudomonas putida, etc. Similarly, in order to produce titanium dioxide NPs, Lactobacillus sp. and B. subtilis are well quoted. Furthermore, Rhodopseudomonas capsulata, P. aeruginosa, B. subtilis, Escherichia coli and B. licheniformis are known for producing gold NPs, and similarly, many researchers also stated about R. palustris, E. coli and Clostridium thermoaceticum for producing cadmium NPs [10,23]. Table 12.1 contains few examples of bacterial and actinomycetes strains that produce various kinds of NPs. 12.2.1.1 Viruses Viruses are single celled intracellular parasites that sabotage the host cell’s replication mechanism and halt the majority of innate cellular activity. Their structure comprises a protein capsid with only one type of nucleic material (either RNA or DNA never both) that may or may not have an envelope surrounding. The ability of viruses to connect and assemble distinct nanosized components holds considerable potential for the development of structured NP assemblies [40]. Viruses constitute an excellent scaffold for molecular assembly into nanodevices because of their tiny dimensions, monodispersity, distinctive structure and range of biochemical assemblies accessible for modification. The capacity of virus-based nanobiocomposites to associate into desirable forms, besides a variety of morphologies, makes them valuable as smart engineered material for development of adaptive nanoobjects. Viruses serve as an excellent model for synthesizing nanoconjugates containing metal nanos. The monodispersed components that these biologically inspired devices form are very responsive to genomic and biochemical alterations. As nanosized assemblies, these viruses exhibit complex yet well-formed structural characteristics that can be comprehensively

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12.2 Biological nanofactories

TABLE 12.1

List of living nanofactories (few examples) used for green synthesis of nanoparticles.

Plant group

Nanoparticles

Size (nm)

Reference

Riccia sp.

Silver

20 50

[24]

Anthoceros

Silver

20 50

[25]

Fissidens minutus

Silver

-

[26]

Campylopus flexuosus

Silver

50 70

[24]

Salvinia minima

Lead

17.2

[27]

Salvinia molesta

Silver

10

[24]

Pteris tripartita

Silver

32

[28]

Gleichenia pectinate

Silver

7.51

[24]

Pteridium aquilinum

Silver

1 50

[29]

Dicranopteris linearis

Silver

40 60

[30]

Azolla microphylla

Gold

3 20

[31]

Adiantum philippense

Gold, silver

10 18

[32]

Cycas sp.

Silver

2 6

[33]

Ginkgo biloba

Silver

15 500

[24]

Juniperus communis

Gold

40 70

[24]

Pinus densiflora

Silver

30 80

[24]

Ephedra procera

Silver

20.4

[24]

Taxus yunnanensis

Silver

6.4 27.2

[24]

Berberis aristata

ZnO

20 40

[24]

Diospyros paniculata

Silver

17

[24]

Hyssops officinalis

ZnO

10 100

[34]

Ipomoea batatas

Silver

Papaver somniferum

PbO, Fe2O3

23, 38

Caulerpa serrulata

Silver

10

Cladosiphon okamuranus

Gold

8 10

[24]

Cystoseira trinodis

Copper oxide

6 7.8

[24]

Bryophytes

Pteridophytes

Gymnosperms

Angiosperms

[35] [36]

Algae

(Continued)

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TABLE 12.1 (Continued) Plant group

Nanoparticles

Size (nm)

Reference

Galaxaura elongata

Gold

3.85 77.13

[3]

Rhizoclonium

Gold

16

[3]

Bacillus brevis

Silver

10 18

[24]

Clostridium pasteurianum

Molybdenum

5 20

[37]

Gluconobacter roseus

Silver

10

[24]

Lactobacillus rhamnosus

Silver

233

[4]

Vibrio natriegens

Selenium

100 400

[24]

Xanthomonas oryzae

Silver

15

[24]

Streptomyces sp.

Silver

5 10

[14]

Rhodococcus sp.

Silver

10 15

[14]

Alternaria alternata

Gold

12

[11]

Aspergillus niger

ZnO

53 69

[15]

Epicoccum nigrum

Silver

1 22

[15]

Macrophomina phaseolina

Silver

5 40

[4]

Phanerochaete chrysosporium

Silver

34 90

[38]

Trichoderma longibrachiatum

Silver

10

[11]

Tobacco mosaic virus (TMV)

CdS, SiO2, Fe2O3, PbS

45 80

[39]

Bacteriophage (M13)

CdS, ZnS

50 100

[39]

SiHa

Gold

20 100

[39]

HeLa

Gold

20 100

[39]

SKNSH

Gold

20 100

[39]

HEK-293

Gold

20 100

[39]

Bacteria

Fungi

Viruses

Human cells

studied by modern structural biological methods [41]. Furthermore, the animal viruses have long been bred to be use in gene therapy, material science and gene delivery. Due to their relative structural component along with chemical stability, ease in production and lack of toxicity or pathogenicity in humans or animals, these viruses (such as plant viruses and bacteriophages) are also being used more and more in nanobiotechnology. Furthermore, over

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the decades, viruses have been used to make quantum dots, a type of nanomaterial. The virus’s outer capsid protein serves an appealing purpose in the synthesis of NPs by providing a strong reactive surface that interacts with the metallic ions. For instance, the size, monodispersity and variety of chemical groups that may be modified in a Cowpea mosaic virus (CPMV) make it a good scaffold for molecular assembly into nanosized devices. Similar to this, TMV, which resembles a linear tube, was explored to be used as a biotemplate for the synthesis of several NPs forms from both inner and outer side of the tubes. TMV was also stated to be used in synthesizing nanowires through the process of metallization. It has been very well reported that the viruses have the ability to produce diverse types of nanoscaled structures called NPs [13]. They distribute inorganic materials like cadmium-sulphide, silicon-dioxide, zinc-sulphide, iron-oxide, etc. Table 12.1 contains few examples of NPs that viruses have produced. 12.2.1.2 Fungi and yeast Due of its widespread use in fields like electronics, medicine, antimicrobials, etc., the synthesis of NPs by fungal strains has become the subject of extensive research. In comparison to bacteria, competent fungi may produce more NPs. They possesses superior abiotic components with intracellular enzymes which help in the synthesis of metals and their oxide NPs. Compared to other microbial species, fungi have a substantial advantage since they have enzymes, biochemicals (peptides) and well-defined reductive components. The most likely method for producing metal NPs is enzymatic reduction by reductase enzyme present in cell walls. In addition, biochemical enzymes present in fungal strains boost the synthesis of stable NPs via reductive characteristics and in large amount. Extracellularly produced NPs are frequently thought to be less or harmless. When compared to other microbes, fungi are more helpful in several respects. In contrast to plant and bacterial cellular components, fungi mycelial matrix can endure flow, temperature, pressure, mixing, agitation and other circumstances in bioreactors or other assemblies. These are diligent to grow, easy to manage and simple to manufacture. Fungal reductive proteins secrete more of them extracellularly, and this makes it simple for downstream processing and other processes. The NPs that precipitated outside of the cells are free of extraneous cellular components and can be employed right away in a variety of applications. Fungi secrete particular enzymes that facilitate in the formation of NPs, which could open the way for genetically modified microbes to overexpress the specific reducing molecules as well as capping agents to regulate the size and structure of the biogenic NPs [42]. In contrast to prokaryotic cells, fungal strains require more effort to be genetically manipulated for the overexpression of particular enzymes that aid in the synthesis of NPs. Fungi may be used for both intracellular and extracellular biological production of metal NPs. Generally, the metal precursors are first added to the fungal culture as part of intracellular synthesis; the metal are later ingested in the biomass. As a result, the extraction of the NPs requires pharmacological techniques, centrifugation sedimentation and filtration methods to shatter the biomass [38]. The green synthesis of NPs through fungi mainly involves a number of enzymes, such as ADH-dependent nitrate reductase, nicotinamide adenine dinucleotide (NADH), oxidoreductases, nitrate/nitrite reductase, hydrolases, sulphate/sulphite reductase, etc. Generally, the key mechanism in fungal strain to produce NPs is the cell wall’s enzymes break down the adsorbed metal ions, creating metal nuclei that further subsequently formed by reducing specific metal ions [42].

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As an example, for the synthesis of NPs, a fungus called Fusarium sp. has been frequently used since it is a ubiquitous, polymorphic filamentous and easily found in water, soil, subterranean or aerial parts of plant, plant detritus and other organic matters. It has been demonstrated that the Fusarium oxysporum can produce Ag-NPs of size ranging from 5 to 15 nm, which are stabilized by mycological proteins that are coated on top of them. Similarly, intracellular synthesis of Au, Ag, cadmium, Zn and molybdenum NPs has also been observed with F. oxysporum. Additionally, some researchers also stated that the fungal strains may need a specific temperature to produce desire NPs [23]. Similarly, Neurospora crassa was used to manufacture intracellularly synthesized Pt-NPs having diameters ranging from 4.5 to 35 nm. Additionally, they have the capacity to create sphere-shaped nanoagglomerates with sizes between 20 and 110 nm. Furthermore, it was also demonstrated that F. oxysporum can make Pt-NPs both extracellularly and intracellularly, although optimal amounts are synthesized when produced intracellularly. The phytopathogenic fungal strain, F. oxysporum, and the endophytic fungal strain called Verticillium sp. have also been explored for synthesize magnetite (common ferrous oxide) NPs intracellularly. The primary drawback of employing fungi to produce NPs is the pathogenicity of the filamentous fungus, which has been widely employed to produce extracellular biomass-free synthesis [23]. For the method to be commercialized, the processing and disposal of the biomass is a significant source of inconvenience. Therefore, there is a need for the creation of novel strategies that make use of non-pathogenic species in order to successfully synthesize and capping of nanosized particles. Nonpathogenic fungi like Neurospora and Trichoderma have been used to make significant progress in this direction. Table 12.1 lists the various kinds of NPs that fungi species have produced. 12.2.1.3 Algae The ability of algae to absorb heavy metals from their environment and produce metallic NPs has been demonstrated well by many researchers. A polyphyletic, artificial assemblage of photosynthetic and noncohesive organisms that evolve to use oxygen is referred as algae. These oxygenic photosynthesizers, which exclude embryophyte land vegetation, are widely attributed and have enormous ecological relevance. Algae have gained popularity in recent years for synthesizing NPs due to their accessibility and efficiency. The enzymes and amino or carboxyl functional groups found in algal cell wall work as reducing agents in ambient settings and provoke synthesis of metal and metal oxide NPs. Almost all algal strains, including blue-green algae, diatoms, green algae, brown algae and red algae, have been observed to produce NPs [42]. The concentration of algal extract or biomass, pH of medium, temperature, incubation time and the type of metal salt used all affect the production of metal and metal oxide NPs. Thus the use of algal strains for NP synthesis offers an affordable, environmentally acceptable alternative to the hazardous chemicals and high energy requirements associated with physiochemical manufacturing. Pigments, polypeptides, polysaccharides, amines, alcohols, amino acids, carboxylic acids, etc., are only a few examples of the diverse biomolecules that have been demonstrated as reducing agents [43]. In addition, these bioactive components also act as a stabilizing and capping agent which lower down the interfacial energy and help in the synthesis of

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249

desired NPs. Marine microalgae have a great potential of converting metal salts of marine to nanoform particles since they are more frequently exposed with salts of marine water than the soil algae. However, a significant obstacle to their use is the creation of monodispersed NPs, which is difficult to form as algae also possess surfactant molecules. Algae as “bio-nano factories” can synthesize metallic NPs from live/swarming and dead biomass (dry) [44]. For example, the capacity of the brown alga Fucus vesiculosus to bioreduce and biosorb Au ions were well stated by researcher. Similarly, Chlorella vulgaris dried algal cells were used to produce Au NPs using reduced tetra-chloroaurate ions. Microalgae are filamentous, colonial, photosynthetic organisms that fall within the Chlorophyta, Charophyta and Bacillariophyta divisions. They contribute significantly to the biodiversity of the globe. An ocean alga called Sargassum wightii produced extracellular Au, Ag and bimetallic (Au/Ag) NPs as well [43]. Algae are simpler to deal with, less dangerous to the environment, and can be produced at ambient temperature and pressure, in regular moist ambiance, albeit with a moderate acidity [44]. For the creation of NPs, diverse strains of algae species being utilized and some of them are enlisted in Table 12.1. 12.2.1.4 Plants Alkaloids, flavonoids, terpenoids, steroids and other bioactive substances found in plants act as perfect reducing agents while synthesizing NPs. Numerous plant parts, such as roots, branches, leaves, petals, fruit, pollen, seeds, pulps, bark, stems and peels, have been explored for the synthesis of NPs. Generally, three main processes are involved in the mechanism for producing NPs utilizing plants. Metal ions are reduced, sometimes referred to as the activation stage, and the reduced metal atoms are then formed [45]. Following that, the growth phase starts, during which tiny nanoentities spontaneously combine to form larger NPs with improved thermodynamic stability. The penultimate stage, referred to as the termination phase, determines the developed NPs of desired shape [16]. Recent studies have used a variety of plants, such as Acalypha indica, Zingiber officinale, Passiflora foetida, Ficus benghalensis, Plumbago zeylanica, Parthenium hysterophorus, Centella asictica, Sapindus rarak, etc., are among examples, to synthesize different kinds of NPs. Plant extracts are more advantageous for the manufacture of green NPs than microbial agent, since it is a one-step, non-pathogenic and economical procedure [42]. Table 12.1 lists the various kinds of NPs that plants have produced. Pteridophytes, Bryophytes, Gymnosperms and Angiosperms are four different groups of plants that are involved in the synthesis of NPs. 1. Pteridophytes are a group of vascular plants that do not produce seeds and reproduce through spores. Examples of pteridophytes include ferns and horsetails. These plants have been shown to produce NPs through the accumulation of metals in their cells. For example, a study of the fern Pteris vittata found that the plant was able to accumulate high levels of cadmium and zinc, which were then converted into NPs through the plant’s metabolic processes [24]. 2. Bryophytes are a group of nonvascular plants that include mosses and liverworts. These plants lack the specialized tissues found in vascular plants, such as xylem and phloem, and rely on diffusion for the transport of water and nutrients. Bryophytes have

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12. A green approach: living nanofactories

been shown to produce NPs through the accumulation of metals in their cells. For example, a study of the moss Bryum argenteum found that the plant was able to accumulate high levels of copper, which was then converted into NPs through the plant’s metabolic processes [46]. 3. Gymnosperms are a group of seed plants that do not produce fruits and have naked seeds. Examples of gymnosperms include conifers and cycads. These plants have been shown to produce NPs through the accumulation of metals in their cells. For example, a study of the gymnosperm Pinus radiata found that the plant was able to accumulate high levels of silver, which was then converted into NPs through the plant’s metabolic processes [24]. 4. Angiosperms are a group of seed plants that produce fruits and have enclosed seeds. Examples of angiosperms include flowering plants and trees. These plants have been shown to produce NPs through the accumulation of metals in their cells. For example, a study of the angiosperm Brassica juncea found that the plant was able to accumulate high levels of gold, which was then converted into NPs through the plant’s metabolic processes [24]. Plant-based NPs, also known as phytosomes, have a wide range of applications in various fields. Some of the key applications are as follows: 1. Drug delivery: Phytosomes are biocompatible and biodegradable, making them suitable for drug delivery applications. They can be used to target specific areas in the body and release drugs at a controlled rate, improving the efficacy and reducing the side effects of the drugs. 2. Food and beverage industry: Phytosomes can be used as natural emulsifiers, stabilizers and thickening agents in food and beverage products. They can improve the texture and stability of the products, and also enhance their nutritional value. 3. Cosmetics and personal care: Phytosomes can be used in skincare and haircare products to improve their moisturizing and anti-ageing properties. They can also be used in sunscreens and other protective creams to provide better UV protection. 4. Agriculture and pest control: Phytosomes can be used as natural pesticides and herbicides in agriculture. They can be more effective and less toxic than synthetic pesticides, and can also reduce the environmental impact of agricultural practices. 5. Environmental remediation: Phytosomes can be used in the clean-up of contaminated soils and waters. They can adsorb heavy metals and other toxic pollutants, and can also biodegrade into harmless by-products. 6. Diagnostics and imaging: Phytosomes can be used as contrast agents in medical imaging procedures, such as magnetic resonance imaging (MRI) and CT scans. They can improve the visibility of the tissues and organs being imaged, and can also help detect abnormalities and diagnose diseases. 7. Biomedical research: Phytosomes can be used in various types of biomedical research, such as tissue engineering and drug discovery. They can provide a natural and biocompatible platform for the growth of cells and the testing of drugs, and can also help improve our understanding of biological processes.

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251

Overall, plant-based NPs have the potential to revolutionize many different fields, from healthcare to agriculture and environmental protection. They offer a natural and sustainable alternative to synthetic NPs, and can provide a wide range of benefits and applications. Additionally to aiding in the fine-tuning of NP size, it helps to remove harmful byproducts. The bioactive macromolecules and phytonutrients (such as phenolics, flavonoids, terpenes, phenolic acids, ethyl alcohol, etc.) content of plant extracts reduces and stabilizes the nanoform metals. These macromolecules are divided into two groups: one capping agents for non-agglomeration and postsurface modification of NPs, and second, redoxed intermediaries for metal reductions. Additionally, the generated NPs are clean and appropriate for applications involving physiologically mediated processes. For example, there have been several researches which stated about the use of various plant’s components and bioactive molecules to synthesize NPs such as Vitex trifolia is known for synthesis of silver NP, which has been shown to have strong antimicrobial properties. Another example is a carbon NP derived from the plant’s leaves, which can be used as a conductive material in electronic devices. Similarly, Benth, or banyan tree, has been used to synthesize NPs such as gold NPs and copper oxide NPs. These NPs have been shown to have antioxidant and antiinflammatory properties, making them potential therapeutic agents for various diseases. Another example, Swertia. chirayita or chirata, has been used to synthesize zinc oxide NPs, which have been shown to have strong antioxidant and antimicrobial properties. These NPs can be used in various applications such as food preservation and wound healing. Cassia alata, or winged coriander, has been used to synthesize iron oxide NPs, which have been shown to have strong magnetic properties and can be used in magnetic resonance imaging. Scadoxus multiflorus, or bitter gourd, has been used to synthesize copper NPs, which have been shown to have strong anti-cancer properties and can be used in targeted drug delivery. Eichhornia crassipes, or water hyacinth, has been used to synthesize silica NPs, which have been shown to have strong adsorption properties and can be used in water purification and waste management. Agathosma betulina, or birch, has been used to synthesize titanium dioxide NPs, which have been shown to have strong UV absorption properties and can be used in sunscreen and other skin care products. Azadirachta indica, or neem, has been used to synthesize gold NPs, which have been shown to have strong antimicrobial and antiinflammatory properties [24]. 12.2.1.5 Human cell line Human cells are heterotrophic in nutrition. For them to survive, continuous energy must be supplied. In vitro circumstances that mimicked their actual cellular environment resulted in the intracellular synthesis of certain metal NPs by both malignant and noncancerous human cells. With an incubation of 1 mM of tetrachloroaurate solution, cancer cells (SiHa an malignant form of cervical-epithelial cells), SKNSH a human neuroblastoma and HeLa malignant cervical epithelial cells, as well as noncancer cells (such as HEK-293nonmalignant human embryonic kidney cells) synthesized gold NPs having size range of 20 100 nm. These NPs were found in the cytoplasm and nucleus of the cell. Compared to the cytoplasmic NPs, the size of these particles was smaller in the nucleus [39]. Table 12.1 enlists some examples of NPs, synthesized by using human cell line.

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12.3 Applications of biologically synthesized nanoparticles The advantages of nanotechnology are rapidly expanding in a variety of sectors. The process of NP formation by biological means is highly efficient and eco-friendly, as it does not involve the use of harmful chemicals and produces minimal waste. The resulting NPs have unique properties and characteristics, such as high surface area, high reactivity and enhanced drug delivery capabilities, which make them useful in various applications such as drug delivery, environmental remediation and renewable energy production. 1. Medicine and healthcare: Biologically synthesized NPs have been extensively used in the medical field for drug delivery and targeted therapy. For instance, gold NPs have been used to deliver cancer drugs directly to tumour cells, increasing their effectiveness and reducing side effects. Additionally, NPs can be used for imaging and diagnostics, such as MRI and fluorescence imaging. 2. Agriculture: Biologically synthesized NPs have been used in the agricultural sector for improving crop yield and quality. For example, silver NPs have been shown to have antibacterial and antifungal properties, making them effective in preventing diseases in plants. Additionally, NPs can be used for nutrient delivery and soil remediation. 3. Environmental protection: Biologically synthesized NPs have been used for water purification and air pollution control. For instance, gold NPs have been used to remove heavy metals from water, and iron oxide NPs have been used for carbon dioxide removal from the air. 4. Energy: Biologically synthesized NPs have been used for energy storage and conversion. For example, gold NPs have been used in solar cells to increase their efficiency, and titanium dioxide NPs have been used in fuel cells to improve their performance. 5. Food and nutrition: Biologically synthesized NPs have been used in the food industry for improving the bioavailability and stability of nutrients. For instance, silver NPs have been used to preserve food, and gold NPs have been used to enhance the absorption of vitamins and minerals in the body. 6. Cosmetics and personal care: Biologically synthesized NPs have been used in the cosmetics and personal care industry for improving the effectiveness and safety of products. For example, gold NPs have been used in sunscreens to block harmful UV rays, and silver NPs have been used in toothpaste to prevent bacterial growth. NP synthesis using biological methods has numerous applications in various sectors. Some of these applications are highlighted in Table 12.2. Furthermore, green NPs are used in many emerging technologies; examples of manufactured goods include moisturisers, desalination, sun filters, inks, stain-resistant cloths, agriculture and medico-pharmaceuticals industries, fabrics industries and wound treatments [39]. NP’s characteristics have sparked a lot of interest in biomedical research. Cancer therapy, medication and gene delivery, pathogen biodetection, tissue engineering, and regenerative medicine are some of the biological applications of NPs. For biomedical applications, biologically generated NPs have been shown to be more effective and biocompatible than physiochemical NPs [22]. Fig. 12.3 shows some important mechanisms that help biologically synthesized NPs to enhance its applications. Moreover, biologically

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12.4 Factors affecting nanoparticle synthesis

TABLE 12.2

253

Applications of biologically synthesized nanoparticles in different sectors.

Sector

Application

Medical sector

Biologically synthesized nanoparticles can be used for drug delivery, imaging and therapy. They can also be used for the detection and treatment of cancer, cardiovascular diseases and infections.

Agriculture industry

Nanoparticles synthesized from plant extracts can be used as natural pesticides and fertilizers. They can also be used for the improvement of plant growth and development.

Food industry

Biologically synthesized nanoparticles can be used as natural food additives and preservatives. They can also be used for the improvement of food quality and safety.

Environmental protection

Nanoparticles synthesized from microorganisms can be used for the remediation of contaminated soil and water. They can also be used for the degradation of pollutants and the production of clean energy.

Cosmetics

Biologically synthesized nanoparticles can be used as natural ingredients in cosmetics and personal care products. They can also be used for the improvement of skin and hair health.

Energy

Nanoparticles synthesized from microorganisms can be used for the production of biofuels and other renewable energy sources. They can also be used for the development of advanced energy storage technologies.

Textile industry

Biologically synthesized nanoparticles can be used as natural dyes and finishing agents in the textile industry. They can also be used for the improvement of textile performance and durability.

Packaging

Nanoparticles synthesized from plant extracts can be used as natural barriers and coatings in packaging materials. They can also be used for the preservation of food and other perishable products.

Construction

Biologically synthesized nanoparticles can be used as natural binders and additives in construction materials. They can also be used for the improvement of the mechanical, thermal, and chemical properties of concrete, bricks, and other building materials.

synthesized NPs from green living factories are ecofriendly, biocompactible and costeffective. In addition, several studies have examined the effectiveness of plant-derived NPs in controlling mosquitoes that transmit diseases including malarial fever, dengue and yellow fever at low concentrations (1 30 ppm), with less hazardous side effects on aquatic life. Some of the biological uses of NPs include drug delivery, cancer treatment, antimicrobial agents, implantation and wound healing, theragnostic, etc. Furthermore, the use of microorganisms and plants as nanofactories for biogenic synthesis has provided a staunch, sustainable, non-toxic and environmentally acceptable method for nanosynthesis [47].

12.4 Factors affecting nanoparticle synthesis The production, characterization and use of NPs are influenced by a number of factors. Numerous studies have shown that the type of adsorbate and the activity of the catalysts

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Human cells Intracellular and extracellular formation occurs with different sizes and which does not require any reducing reagents

Fungi Capability to secrete a large number of enzymes Scalability is made simple

Plants There are numerous secondary metabolites. There are numerous sources available. Cheap and simple to use

Biogenic nanoparticles Virus Uses as nanocages for the entrapment of substances (metals) resulting in metalized or mineralized building blocks and target drug delivery

FIGURE 12.3

Bacteria Adaptability in extreme conditions Brief life-cycle Algae Cheap raw material

Biogenic nanofactories and their unique features.

used in the synthesis process can alter the nature of the NPs that are produced. Some of them have described the synthesized NP dynamic nature as having multiple types of symptoms and implications that alter with time, environment and other factors. The pH of the medium, environment, temperature, particle size, the concentration and quantity of the extracts utilized, pore size, the amount of the natural resources used and proximity, above all the protocols employed for the synthesis process are additional significant parameters that affect the synthesis of NPs. These include: 1. Type of biological agent: The type of biological agent used can have a significant impact on the synthesis of NPs. For example, bacteria and fungi are commonly used for this purpose due to their ability to produce NPs through the secretion of extracellular enzymes. However, other biological agents such as plant cells, algae and yeast can also be used for NP synthesis.

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255

2. Substrate concentration: The concentration of the substrate used for NP synthesis can affect the size, shape and composition of the resulting NPs. Higher concentrations of the substrate can result in larger NPs, while lower concentrations can result in smaller NPs. 3. Temperature and pH: The temperature and pH of the synthesis environment can also affect the synthesis of NPs. In general, higher temperatures and more acidic pH values can result in faster NP synthesis, while lower temperatures and more alkaline pH values can slow down the synthesis process. 4. Reaction time: The length of time that the synthesis reaction is allowed to run can also affect the size, shape and composition of the resulting NPs. In general, longer reaction times can result in larger NPs, while shorter reaction times can result in smaller NPs. 5. Agitation: The level of agitation or mixing in the synthesis reaction can also affect the size, shape and composition of the resulting NPs. Higher levels of agitation can result in more uniform NPs, while lower levels of agitation can result in more irregular NPs. 6. Additives: The addition of certain chemicals or additives to the synthesis reaction can affect the size, shape and composition of the resulting NPs. For example, the addition of surfactants can help to control the size and shape of the NPs, while the addition of stabilizers can help to prevent the aggregation or clumping of the NPs. 7. Surface charge: The surface charge of the NPs can also affect their synthesis and stability. Positively charged NPs can be synthesized using cationic surfactants, while negatively charged NPs can be synthesized using anionic surfactants. 8. Growth conditions: The growth conditions of the biological organism, such as temperature, pH, nutrient availability and oxygen levels, can greatly affect the synthesis of NPs. For example, high temperature and low pH can inhibit NP synthesis, while optimal nutrient availability and oxygen levels can promote it. 9. Precursor materials: The type and concentration of precursor materials used in the synthesis process can affect the size, shape and composition of the resulting NPs. For example, using a high concentration of a specific metal can produce larger and more uniform NPs compared to using a low concentration. 10. Processing methods: The processing methods used during the synthesis process, such as ultrasonication, stirring or heating, can affect the size, shape and composition of the resulting NPs. For example, using ultrasonication can produce smaller and more uniform NPs compared to stirring. 11. Surface modifications: Surface modifications, such as coating or functionalization, can affect the properties and stability of the resulting NPs. For example, coating NPs with a specific polymer can increase their stability and enhance their bioactivity. 12. Storage conditions: The storage conditions of the NPs, such as temperature, humidity and light exposure, can affect their stability and performance. For example, storing NPs at high temperature and high humidity can cause them to aggregate and lose their activity, while storing them in a cool and dark environment can preserve their properties. 13. Final application: The final application of the NPs can also affect their synthesis and properties. For example, synthesizing NPs for drug delivery requires different size, shape and surface modifications compared to synthesizing NPs for solar cell applications.

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12. A green approach: living nanofactories

Overall, the synthesis of NPs by biological means is influenced by various factors and parameters, including the type of biological organism used, growth conditions, precursor materials, processing methods, surface modifications, storage conditions and final application. Optimizing these factors and parameters can enhance the synthesis and performance of NPs for various applications [48,49].

12.5 Future prospects The future of green or biologically synthesized NPs is very promising. These NPs have the potential to revolutionize the way we approach many different fields, including medicine, energy and environmental protection. One of the key benefits of green or biologically synthesised NPs is their biocompatibility. These NPs are derived from natural sources such as plants or bacteria, and are therefore nontoxic and safe for use in the human body. This makes them ideal for use in medical applications, such as drug delivery or imaging. Another major advantage of green or biologically synthesized NPs is their low cost and eco-friendly production methods. Traditional NPs are often synthesized using complex and expensive chemical processes that can generate hazardous waste. In contrast, green or biologically synthesized NPs are produced using simple and sustainable techniques, such as fermentation or plant extraction. This not only reduces the environmental impact of NP production, but also makes it more accessible and affordable. One area where green or biologically synthesized NPs are already making an impact is in renewable energy. These NPs can be used to improve the efficiency of solar cells and batteries, making them more cost-effective and sustainable. For example, titanium dioxide NPs derived from plants have been shown to increase the conversion efficiency of solar cells by up to 25%. Similarly, bacterial-derived cobalt oxide NPs have been used to improve the performance of lithium-ion batteries. In addition, green or biologically synthesized NPs are also being explored for their potential to clean up hazardous waste and pollution. For instance, bacterial-derived iron oxide NPs have been used to remove heavy metals from contaminated water. These NPs can also be used to break down pollutants in the air, such as volatile organic compounds, which are harmful to human health and the environment. Overall, the future of green or biologically synthesized NPs is very bright. With their biocompatibility, low cost and eco-friendly production methods, these NPs have the potential to revolutionize a wide range of industries, from medicine to renewable energy. As research and development in this field continues to advance, we can expect to see even more exciting and innovative applications of these NPs in the future.

12.6 Conclusion With the ability to produce and employ harmless NPs, green NP synthesis is expected to gain prominence. Contributions from numerous domains, including physics, chemistry and biology, are anticipated to lead to the development of novel green NP synthesis techniques. The industry has a lot of promise, despite the numerous challenges that must be solved. Understanding the precise mechanisms could aid in the long-term advancement of green

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nanotechnology. In the past few decades, there has been a lot of research on the “green” manufacturing of metals and the NPs made from their oxides. Numerous biocomponents, including bacteria, fungus, yeast, plants, algae and even viruses, are frequently employed for the synthesis of different NPs. This chapter mainly concentrated on the creation of different NPs from various biological factories and their uses in a variety of disciplines. For a more environmentally friendly way to create NPs, unsafe substances such sodium borohydride and diazane (N2H4) must be avoided as well as more reliable and secure reducing, sustainable and capping agents must be incorporated. The following are the main issues that came up when creating NPs in a green manner: pH, salt content, contact time and temperature are just a few of the factors that affect how stable high-yielding NPs. The biological entities that are used affect these variables. The compounds found in the filtrate of organic material should be carefully investigated in order to identify the characteristics of each individual component in NPs produced biologically. Additional optimization research is needed for green synthesis methods of a certain size and shape. Additionally, more study is required, especially for biological applications, in the synthesis of NPs with specific physicochemical features. Scaling up production with ecologically sustainable methods is a problem when trying to commercialize NPs. The mechanistic component of producing NPs with green technologies requires more research. The green NPs synthesized from biofactories may be useful for a variety of applications, including immunoassays, the administration of therapeutic drugs, cancer therapies, chemotherapeutics, and sterile agents, biomedicine, biotechnology, biomaterials, phytopathogen management, biosensing, bioremediation, as well as bandages, pharmaceuticals and consumer goods. A deeper understanding of green chemistry as a process for creating NPs thus opens up new opportunities.

References [1] J. Jeevanandam, A. Barhoum, Y.S. Chan, A. Dufresne, M.K. Danquah, Review on nanoparticles and nanostructured materials: history, sources, toxicity and regulations, Beilstein J. Nanotechnol. 9 (2018) 1050 1074. Available from: https://doi.org/10.3762/bjnano.9.98. [2] M. Nasrollahzadeh, M. Sajjadi, S.M. Sajadi, Z. Issaabadi, Green Nanotechnology, First ed., Interface Science and Technology, Vol. 28, Elsevier Ltd., 2019. Available from: https://doi.org/10.1016/B978-0-12-8135860.00005-5. [3] T. Thunugunta, A.C. Reddy, D.C. Lakshmana Reddy, Green synthesis of nanoparticles: current prospectus, Nanotechnol. Rev. 4 (2015) 303 323. Available from: https://doi.org/10.1515/ntrev-2015-0023. [4] K.N. Thakkar, S.S. Mhatre, R.Y. Parikh, Biological synthesis of metallic nanoparticles, Nanomed. Nanotechnol. Biol. Med. 6 (2010) 257 262. Available from: https://doi.org/10.1016/j.nano.2009.07.002. [5] I. Hussain, N.B. Singh, A. Singh, H. Singh, S.C. Singh, Green synthesis of nanoparticles and its potential application, Biotechnol. Lett. 38 (2016) 545 560. Available from: https://doi.org/10.1007/s10529-015-2026-7. [6] S.A. Khan, C.S. Lee, Green biological synthesis of nanoparticles and their biomedical applications. In: Nanotechnology in the Life Sciences (2020). https://doi.org/10.1007/978-3-030-44176-0_10. [7] X. Fu, J. Cai, X. Zhang, W. Di, H. Ge, Y. Hu, Top-down fabrication of shape-controlled, monodisperse nanoparticles for biomedical applications, Adv. Drug. Delivery Rev. 132 (2018) 169 187. Available from: https:// doi.org/10.1016/j.addr.2018.07.006. [8] A.M. Ealias, M.P. Saravanakumar, A review on the classification, characterisation, synthesis of nanoparticles and their application, IOP Conf. Series: Mater. Sci. Eng. 263 (2017). Available from: https://doi.org/10.1088/ 1757-899X/263/3/032019. [9] K. Parveen, V. Banse, L. Ledwani, Green synthesis of nanoparticles: their advantages and disadvantages, AIP Conf. Proc. 1724 (2016). Available from: https://doi.org/10.1063/1.4945168.

Green Chemistry Approaches to Environmental Sustainability

258

12. A green approach: living nanofactories

[10] C. Pandit, A. Roy, S. Ghotekar, A. Khusro, M.N. Islam, T. Bin, et al., Biological agents for synthesis of nanoparticles and their applications, J. King Saud. Univ. - Sci. 34 (2022) 101869. Available from: https://doi.org/ 10.1016/j.jksus.2022.101869. [11] A. Gour, N.K. Jain, Advances in green synthesis of nanoparticles, Artif. Cells, Nanomed. Biotechnol. 47 (2019) 844 851. Available from: https://doi.org/10.1080/21691401.2019.1577878. [12] N.I. Hulkoti, T.C. Taranath, Biosynthesis of nanoparticles using microbes-a review, Colloids Surf. B: Biointerfaces 121 (2014) 474 483. Available from: https://doi.org/10.1016/j.colsurfb.2014.05.027. [13] A.S. Gubarev, A.A. Lezov, M.E. Mikhailova, A.S. Senchukova, N.G. Mikusheva, V.Y. Sobolev, et al., Green synthesis of silver nanoparticles with the tobacco mosaic virus, Rev. Adv. Chem. 11 (2021) 189 196. Available from: https://doi.org/10.1134/s207997802103002x. [14] G. Gahlawat, A.R. Choudhury, A review on the biosynthesis of metal and metal salt nanoparticles by microbes, RSC Adv. 9 (2019) 12944 12967. Available from: https://doi.org/10.1039/c8ra10483b. [15] N.S. Ahmad, S. Munir, N. Zeb, J. Ali, M. Bilal, M. Omer, et al., Green nanotechnology: a review on green synthesis of silver nanoparticles-an ecofriendly approach, Int. J. Nanomed. (2019) 5087 5107. [16] S. Jadoun, R. Arif, N.K. Jangid, R.K. Meena, Green synthesis of nanoparticles using plant extracts: a review, Environ. Chem. Lett. 19 (2021) 355 374. Available from: https://doi.org/10.1007/s10311-020-01074-x. [17] J. Singh, T. Dutta, K.H. Kim, M. Rawat, P. Samddar, P. Kumar, “Green” synthesis of metals and their oxide nanoparticles: applications for environmental remediation, J. Nanobiotechnol. 16 (2018) 1 24. Available from: https://doi.org/10.1186/s12951-018-0408-4. [18] D.O. Plaza, C. Gallardo, Y.D. Straub, D. Bravo, J.M. Pe´rez-Donoso, Biological synthesis of fluorescent nanoparticles by cadmium and tellurite resistant Antarctic bacteria: exploring novel natural nanofactories, Microb. Cell Factories 15 (2016) 1 11. Available from: https://doi.org/10.1186/s12934-016-0477-8. [19] P. Golinska, M. Wypij, A.P. Ingle, I. Gupta, H. Dahm, M. Rai, Biogenic synthesis of metal nanoparticles from actinomycetes: biomedical applications and cytotoxicity, Appl. Microbiology Biotechnol. 98 (2014) 8083 8097. Available from: https://doi.org/10.1007/s00253-014-5953-7. [20] P. Singh, Y.J. Kim, D. Zhang, D.C. Yang, Biological synthesis of nanoparticles from plants and microorganisms, Trends Biotechnol. 34 (2016) 588 599. Available from: https://doi.org/10.1016/j.tibtech.2016.02.006. [21] P.R. Leduc, M.S. Wong, P.M. Ferreira, R.E. Groff, K. Haslinger, M.P. Koonce, et al., Towards an in vivo biologically inspired nanofactory, Nat. Nanotechnol. 2 (2007) 3 7. Available from: https://doi.org/10.1038/ nnano.2006.180. [22] V.S.A.A. Tiwari, Combating pathogenic microbes through E. Coli based silver nano tools Vandana, Int. J. Pharma Bio Sci. 7 (2016) 367 375. [23] M. Shah, D. Fawcett, S. Sharma, S.K. Tripathy, G.E.J. Poinern, Green synthesis of metallic nanoparticles via biological entities, Mater. 8 (2015). Available from: https://doi.org/10.3390/ma8115377. [24] S. Srivastava, Z. Usmani, A.G. Atanasov, V.K. Singh, N.P. Singh, A.M. Abdel-Azeem, et al., Biological nanofactories: using living forms for metal nanoparticle synthesis, Mini-Rev. Med. Chem. 21 (2020) 245 265. Available from: https://doi.org/10.2174/1389557520999201116163012. [25] F.W. Li, T. Nishiyama, M. Waller, E. Frangedakis, J. Keller, Z. Li, et al., Anthoceros genomes illuminate the origin of land plants and the unique biology of hornworts, Nat. Plants 6 (2020) 259 272. Available from: https://doi.org/10.1038/s41477-020-0618-2. [26] T. Kautz, S. Rob Gradstein, On the ecology and conservation of Spruceanthus theobromae (Lejeuneaceae, hepaticae) from western Ecuador, Bryologist 104 (2001) 607 612. Available from: https://doi.org/10.1639/ 0007-2745. [27] T. Hoffmann, C. Kutter, J.M. Santamarı´a, Capacity of Salvinia minima baker to tolerate and accumulate As and Pb, Eng. Life Sci. 4 (2004) 61 65. Available from: https://doi.org/10.1002/elsc.200400008. [28] X. Baskaran, A.V.G. Vigila, T. Parimelazhagan, D. Muralidhara-Rao, S. Zhang, Biosynthesis, characterization, and evaluation of bioactivities of leaf extract-mediated biocompatible silver nanoparticles from an early tracheophyte, Pteris tripartita Sw, Int. J. Nanomed. 11 (2016) 5789 5805. Available from: https://doi.org/10.2147/IJN.S108208. [29] R.H. Marrs, A.S. Watt, Biological flora of the British Isles: Pteridium aquilinum (L.) Kuhn, J. Ecol. 94 (2006) 1272 1321. Available from: https://doi.org/10.1111/j.1365-2745.2006.01177.x. [30] Z.A. Zakaria, Z.D.F. Abdul Ghani, R.N.S. Raden Nur, H.K. Gopalan, M.R. Sulaiman, A.M. Mat Jais, et al., Antinociceptive, anti-inflammatory, and antipyretic properties of an aqueous extract of Dicranopteris linearis leaves in experimental animal models, J. Nat. Med. 62 (2008) 179 187. Available from: https://doi.org/ 10.1007/s11418-007-0224-x.

Green Chemistry Approaches to Environmental Sustainability

References

259

[31] A. Arora, S. Saxena, Cultivation of Azolla microphylla biomass on secondary-treated Delhi municipal effluents, Biomass Bioenergy 29 (2005) 60 64. Available from: https://doi.org/10.1016/j.biombioe.2005.02.002. [32] D.G. Sant, T.R. Gujarathi, S.R. Harne, S. Ghosh, R. Kitture, S. Kale, et al., Adiantum philippense L. Frond assisted rapid green synthesis of gold and silver nanoparticles, J. Nanopart. (2013) 1 9. Available from: https://doi.org/10.1155/2013/182320. [33] K. Su, C. Quan, Y.S. Liu, Cycas fushunensis sp. nov. (Cycadaceae) from the Eocene of northeast China, Rev. Palaeobotany Palynology 204 (2014) 43 49. Available from: https://doi.org/10.1016/j.revpalbo.2014.02.008. [34] F. Fathiazad, S. Hamedeyazdan, A review on Hyssopus officinalis L: composition and biological activities, Afr. J. Pharm. Pharmacol. 5 (2011) 1959 1966. Available from: https://doi.org/10.5897/AJPP11.527. [35] M.K. Alam, A comprehensive review of sweet potato (Ipomoea batatas (L.] Lam): revisiting the associated health benefits, Trends Food Sci. Technol. 115 (2021) 512 529. Available from: https://doi.org/10.1016/j. tifs.2021.07.001. [36] F. Labanca, J. Ovesna`, L. Milella, Papaver somniferum L. taxonomy, uses and new insight in poppy alkaloid pathways, Phytochemistry Rev. 17 (2018) 853 871. Available from: https://doi.org/10.1007/s11101-0189563-3. [37] H. Biebl, Fermentation of glycerol by Clostridium pasteurianum - Batch and continuous culture studies, J. Ind. Microbiol. Biotechnol. 27 (2001) 18 26. Available from: https://doi.org/10.1038/sj.jim.7000155. [38] I. Kumar, M. Mondal, N. Sakthivel, Green synthesis of phytogenic nanoparticles, Green Synthesis, Characterization and Applications of Nanoparticles, Elsevier Inc, 2019. Available from: https://doi.org/ 10.1016/b978-0-08-102579-6.00003-4. [39] P. Velusamy, G.V. Kumar, V. Jeyanthi, J. Das, R. Pachaiappan, Bio-inspired green nanoparticles: synthesis, mechanism, and antibacterial application, Toxicol. Res. 32 (2016) 95 102. Available from: https://doi.org/ 10.5487/TR.2016.32.2.095. [40] A. Rana, K. Yadav, S. Jagadevan, A comprehensive review on green synthesis of nature-inspired metal nanoparticles: mechanism, application and toxicity, J. Clean. Prod. 272 (2020) 122880. Available from: https://doi. org/10.1016/j.jclepro.2020.122880. [41] J. Purohit, A. Chattopadhyay, N.K. Singh, Green synthesis of microbial nanoparticle: approaches to application, Nanotechnol. Life Sci. (2019) 35 60. Available from: https://doi.org/10.1007/978-3-030-16534-5_3. ̇ ˘ [42] H. Nadaroglu, A. Alayli Gu¨ngo¨r, S. Ince, Synthesis of nanoparticles by green synthesis method, Int. J. Innovat. Res. Rev. 1 (2017) 6 9. Available from: http://www.injirr.com/article/view/4. [43] D. Parial, H.K. Patra, A.K.R. Dasgupta, R. Pal, Screening of different algae for green synthesis of gold nanoparticles, Eur. J. Phycol. 47 (2012) 22 29. Available from: https://doi.org/10.1080/09670262.2011.653406. [44] D. Chugh, V.S. Viswamalya, B. Das, Green synthesis of silver nanoparticles with algae and the importance of capping agents in the process, J. Genet. Eng. Biotechnol. 19 (2021). Available from: https://doi.org/10.1186/ s43141-021-00228-w. [45] M. Rai, A. Yadav, Plants as potential synthesiser of precious metal nanoparticles: Progress and prospects, IET Nanobiotechnol. 7 (2013) 117 124. Available from: https://doi.org/10.1049/iet-nbt.2012.0031. [46] H. Bird, Moss (bryophyte) mediated synthesis and characterization of silver nanoparticles from Campylopus flexuosus, J. Pharm. Sci. Res. 9 (2017) 292 297. [47] P. Kuppusamy, M.M. Yusoff, G.P. Maniam, N. Govindan, Biosynthesis of metallic nanoparticles using plant derivatives and their new avenues in pharmacological applications an updated report, Saudi Pharm. J. 24 (2016) 473 484. Available from: https://doi.org/10.1016/j.jsps.2014.11.013. [48] J.K. Patra, K.H. Baek, Green nanobiotechnology: factors affecting synthesis and characterization techniques, J. Nanomater. (2014). Available from: https://doi.org/10.1155/2014/417305. [49] A.A. Yaqoob, K. Umar, M.N.M. Ibrahim, Silver nanoparticles: various methods of synthesis, size affecting factors and their potential applications a review, Appl. Nanosci. (Switz.) 10 (2020) 1369 1378. Available from: https://doi.org/10.1007/s13204-020-01318-w.

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C H A P T E R

13 Green energy and green fuels technologies Ranjan Kumar Basak1 and Ashish Kumar Asatkar2 1

Department of Chemistry, Shivharsh Kisan P.G. College Basti, Basti, Uttar Pradesh, India 2 Department of Chemistry, Satyanarayan Agarwal Govt. Arts & Commerce College, Kohka-Newra (Tilda), Dist. Raipur, Chhattisgarh, India

13.1 Introduction Green fuels are the type of fuels that are either ecofriendly or are environmentally benign. These fuels do not pose serious threat to the sustainability of the environment and to the lives of plants and animals. Fossil fuels that make up approximately 80% of the total energy consumption by mankind presently are exhaustible [1] in nature and produce greenhouse gases, for example, COx, SOx and NOx. More than two-third of greenhouse gases are generated from fossil fuels. According to a study the fossil fuels may last for atmost one more century. The greenhouse gases are bringing about global warming, melting of the glaciers of the poles and the mountains, erratic rainfall and droughts, depletion of the ozone layer, etc. The ultimate source of energy of all the green fuels is the sun either directly or indirectly. Most of the green fuels are considered replenishable/renewable except for geothermal energy. Sustainability and replenishablity of the green fuels are on human usage time scales. However, on larger time scales geothermal energy is replenishable. Green fuels are also clean fuels [2] except the nuclear fuels. The clean fuels are substances or modes of energy generation that do not produce environmentally harmful waste products. The green fuels do not produce waste products as only the kinetic and potential energy stored in natural substances is used for generation of electricity and heat. Generally, green fuel technologies do not involve chemical changes rather only utilize the physical changes in order to harness the stored energies in the natural resources like wind, water, tides, waves, etc. The only exception to this generality is the chemical reactions used in fuel cells where the product is water along with other gases. However, the nuclear energy extraction produces radioactive wastes and poses a serious threat to its management and disposal.

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Heavy dependence on fossil fuels for various energy needs has rendered our environment fragile and unsustainable even in the short run. The usage of fossil fuels has increased the proportions of CO2, CO, NOx, SOx and particulate matter in the atmosphere that have led to global warming, frequent droughts, floods, rising sea level, depleting ground water table, depletion of the ozone layer, acid rains, smog, drying up of rivers, depleting soil fertility and other problems as well. Most of these problems can be fixed by shifting from usage of fossil fuels towards green energy technologies and green fuels. Sustainable development of our civilization on Earth is possible only if our environment and the planet remain healthy. This chapter discusses most of the green energy technologies and green fuels.

13.2 Green fuels Humans have been using solar energy for heating of water, disinfection, drying of cloths and food items since prehistoric times. Similarly, wind energy has been used for rowing of boats, drying purposes, etc. Cattle dung has been used as fuel for cooking and fertilizers. Tides have been used for rowing/sailing of big boats in shallow coastal regions. In various regions of earth, the natural resources like sunlight, wind, wave energy, cattle dung, flowing water and rainwater have been used in several ways. However, in the modern times need of energy has risen enormously and the use of fossil fuels is unsustainable both environmentally and dwindling natural reserves of the fuel. Coupled with rising fossil fuel prices and geopolitical issues that affect its availability, there is an urgent need to completely switch to alternative sources of energy either fully or even partially. The various alternative or nonconventional or renewable sources of energy are listed as follows

13.2.1 Solar energy 13.2.1.1 Introduction The Earth receives more energy from the sun in an hour than total energy consumed by the whole mankind from all the sources of energy throughout the year [3]. Life without solar energy is not possible on Earth. Sun is the ultimate source of energy for Earth in all aspects. Except geothermal energy all the forms of energy here on Earth are obtained directly or indirectly from the Sun. This energy is consumed by mankind for transportation, industrial production, domestic purposes, commercial use and miscellaneous uses. Solar radiation carries energy throughout its electromagnetic spectrum. However, mankind utilizes the infrared part and UV-Vis part only of the spectrum to harness energy for its use. 13.2.1.2 Use of solar power However, the mankind uses only a very small fraction of solar energy. Solar energy is utilized by mankind in three major ways [4] for his energy needs.

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1. Heating effect: The infrared rays of the spectrum produces heating sensation in our body. The solar heating of the infrared part of the spectrum is utilized in the following ways. a. The heating effect is used for cooking in solar cookers. b. Heating water for usage at home and industries through solar water heaters. c. Production of electricity by concentrating solar heat [5] falling over a larger area of the earth surface to comparatively a very small area by the using large mirrors and lenses. The high temperature produced at the samll area is used to heat up oil or a fluid or melting of salts and store the thermal energy. This stored heat is used to generate electricity during the hour of need by turning turbines through various ways. This method of generation of electricity requires large area and infrastructure with huge investment. Concentrating solar power generators are showing a very slow growth due to heavy investment. Most of the recently added concentrating solar power generation capacity addition has occurred in China. 2. Use of photovoltaics to generate electricity: This is a more widely used process of generation of electricity worldwide. This process has been put to commercial use very widely. The process is based on photovoltaic effect. The solar cells are made up of photosensitive semiconductors that are usually based on silicon and germanium. A doped n-type semiconductor and p-type semiconductor are put together, thereby producing p-n junction at the interface. The material is electrically neutral but the ntype semiconductor has excess electron and the p-type has excess holes. When light shines on the solar cell a flow of electron from n-type semiconductor to the p-type semiconductor occurs, thus producing an electric field across the p-n junction. This voltage difference across the p-n junction is used by inserting electrodes across the p-n junction to extract current to an external circuit. This current from the solar cell being DC is converted to AC through a inverter and used for various purposes. The flow of current/voltage across the p-n junction is proportional to the intensity of solar light falling on the solar cells. The greater the intensity of solar radiation falling on the solar cells, the greater the current produced. The solar cells produce electricity even on cloudy days when diffused sunlight falls on the solar cells. The solar cells are rated based on the electricity generated on exposure of full sunlight in terms of KWP, that is, power generated at peak sunlight. As such voltage generated by a solar cells is very little so that a number of solar cells are assembled on a framework which is called solar module. The solar cells are connected in series to generate a greater voltage. A number of modules placed on a preinstalled framework that is ready to be installed is called a solar panel. A number of solar panels installed in a solar system for generating electricity is called solar array. Average potential generated by individual solar cells is 0.5 to 0.6 V. Usually solar cells have an efficiency around 20%, that is, they can convert around 20% of the solar energy falling on the cell to electricity [6]. Usually the solar modules have 60 or 72 solar cells arranged in lattice fashion as shown in the figure. The solar modules have a power rating of 250 400 W, that is, they produce 250 400 W of power per hour. The electricity produced by solar cell may be stored in the battery for later use or directly fed into the electricity grid or the main power transmission line of the area to be used elsewhere. This method of power generation has been adopted by number of countries including India, China, United States, Brazil, etc. (Fig. 13.1).

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FIGURE 13.1 Representation of solar cells, solar module and solar system. Source: From https://energyresearch. ucf.edu/wp-content/uploads/2017/01/pv-cell-to-array-800x572.png

Chapin et al. invented the solar cells at Bell Labs, United States in 1954 [7]. The solar cells being used presently are of first- and second-generation solar cells. However, there are three generations of solar cells. The first-generation cells are made up of monocrystalline and polycrystalline silicon [8]. The second-generation solar cells are layer/layers of photovoltaic material deposited on solid surfaces such as glass, plastics, etc. The third-generation solar cells are in a phase of development. They include organic-inorganic perovskite (CH3NH3PbI3) solar cells, inorganic solar cells, quantum dot solar cells, organic tandem solar cells and dye-sensitized solar cells. Perovskite solar cells have shown a promising efficiency of 25.5% recently [9,10]. Perovskite materials are of general formula MAPbX3 (where MA 5 CH3NH31, X 5 Cl, Br, I) [11]. Perovskite materials being a very cost-effective thus is very attractive for using it in solar cells. The stability of the device and its functions over a considerable period is low and requires much R&D before full-scale commercialization. The solar cells operate under full sunshine thus has to bear rising temperature during sun hours and has to bear the low temperatures of night and the cold seasons [12]. Thus solar cells of perovskite must be made resistant to temperature variations on daily basis as well as seasonally. Also the solar cells must be chemically inert to effect of O2 and moisture. Perovskite solar cells must also stable to UV radiations of sun rays as well.

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The silicon-based first- and second-generation solar cells are very stable towards fluctuations of temperature, moisture, oxygen and UV radiations, and thus are in commercial use presently. However, silicon-based solar cells suffer from degradation over a long periods of use due to mechanical fractures of the silicon sheets, corrosion of the electrodes and module elements. The solar panels are encapsulated with ethylene vinyl acetate material that protects the solar cells from moisture. Cerium-doped glass encapsulation of the solar panels safeguards the solar cells from UV rays. India had a target of achieving power generation of 175 GW by 2022 through renewable energy sources [13]. But by the end of year 2022, the installed capacity of power generation through renewable resources stands out at 120.90 with 26.53% of the total power generation capacity installed in the country. India now stands at fourth position globally in installed capacity of power generation through renewable resources. The power generation capacity through solar photovoltaic (PV) cells stands out at 46 GW out of 175 GW power generation capacity from renewable sources. The tariff rates for power generation from solar PV projects are at a very low at Rs 1.99 per unit. Presently, India has established 34 solar parks spanning in 21 states with an aggregate capacity of 20 GW of installed capacity. India has established a solar alliance on 30 November 2015, and in partnership with France launched International Solar Alliance in Paris climate summit (COP-21) [14] to harness solar energy by the tropical countries. There are 123 signatories to the solar alliance. It is an alliance based on treaty and inter-governmental body would work towards reducing dependence on use of fossil fuels over time. India has established a number of solar parks by installing solar PV cells to generate electricity. The biggest solar park of India is in Rewa, Madhya Pradesh. 3. Use of solar energy in producing solar fuels: Solar energy is also utilized in producing fuels that are storable and transportable. The fuels that can be obtained using solar energy are H2, MeOH, CH4, HCOOH, HCOH, N2H4 and NH3 employing various processes [15,16]. These fuels can be used on demand just like fossil fuels. Solar energy is used to extract fuels from biomass. Thermochemical and biochemical techniques are used to extract biochar, bio-oil and gases that can be used as fuels [17,18]. The biomasses such as bagasse, cotton stalk, coconut shells, tea and coffee wastes, groundnut shells, soya husk, de-oiled cakes, saw dust, jute wastes mahua, Jatropha, curcas, etc., are subjected to thermochemical processes like combustion or gasification or pyrolysis to obtain various types of fuels [19]. Combustion is burning of biomass in full supply of air/oxygen. The process yields heat energy to be used directly or can be stored in some form to be used on demand. Gasification is burning of biomass in limited supply of air/oxygen. The process yields methane and syngas (CO 1 H2), which are fuels and can be used in various forms. Pyrolysis is burning of biomass in absence of air/oxygen. The process yields bio-oil, biochar and pyrolytic gases. These thermochemical processes can be done using solar energy in the form of thermal energy or heating by using electricity generated from solar PV cells or even in the form of microwave heating. Biochemical decomposition of biomass can be done either by digestion process or fermentation. Digestion process generates fuel gases like methane, while fermentation generates bioethanol and biodiesel. The energy and fuels obtained from biomass degradation are used for transportation, power generation and also in the agricultural sector.

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Fuels and chemicals can also be obtained from reduction of CO2 using energy obtained from the solar radiation [20]. CO2 can be thermochemically or photochemically reduced in the presence of certain catalysts to methanol, formic acid, formaldehyde, methane and carbon monoxide. These chemicals are used in industries as well as fuels for certain combustion engines and fuel cells [10,21,22]. The various methods of reduction of CO2 and their respective products obtained are as follows. Biophotosynthetically: formic acid, methanol and methane Photothermally: methanol and methane Microbial photochemically: methane, acetate (CH3COO-) Photosynthetically and photocatalytically: methanol, carbon monoxide and methane Photoelectrochemically: formic acid, methane, methanol and carbon monoxide Photovoltaic and electrochemically: formic acid, ethene and carbon monoxide. CO2 being very stable thermodynamically requires a lot of energy for its reduction. However, during its reduction a number of products can be obtained depending upon the amount of energy supplied [23 25]. Production of various fuels and chemicals using solar energy requires the following reduction potentials (Fig. 13.2) [26]. Among the fuels obtained from CO2 reduction, formic acid and methanol are liquids at room temperature and thus can be used as fuels in liquid fuel cells to obtain energy (Fig. 13.3). Formaldehyde being soluble in water can be used as aqueous solution as fuels in liquid fuel cells. Besides solar reduction of carbon dioxide to obtain carbon-based fuels, molecular nitrogen can also be reduced electrochemically to obtain hydrazine and ammonia (Fig. 13.4). Hydrazine is liquid at room temperature and therefore can be used as fuel in liquid fuel cells. However, ammonia being highly soluble in water can be used as liquid fuels in aqueous form. The EMF obtained from the oxidation of the nitrogen-based fuels is as given in Fig. 13.5. Hydrazine hydrate (N2H4.H2O) [27 29] remains in liquid state between the temperature range of 60 C to 119 C (i.e., 213K to 392K). It has a hydrogen density of

FIGURE 13.2

Reduction potentials of CO2 to obtain various fuels.

FIGURE 13.3 EMF obtained from fuels in the fuels cell operation.

FIGURE 13.4 Reduction of molecular nitrogen using energy from solar radiation.

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FIGURE 13.5 EMF obtained from fuels in the fuel cell operation.

FIGURE 13.6

Fuel cell operation in hydrogen

peroxide.

FIGURE 13.7 Fuel cell operation in ethyl alcohol and ethylene glycol.

8% by weight, which is considerably high. Hydrated hydrazine can be safely stored and transported. Therefore it has a high potential of being used as a fuel in vehicular transport. However, anhydrous hydrazine suffers from drawback of flammability of vapour and detonation in absence of air [30]. Thus high degree of precaution must be exercised in handling anhydrous hydrazine. Dilution of anhydrous hydrazine reduces risk of accidents. Although with the increase of dilution, the probability of accidents reduces but a balance must be sought between safety, cost and damage to the environment. Ammonia is also a good alternative to hydrogen for use in solid oxide fuel cells (SOFC) [31]. It has a high hydrogen density of 17.8% by weight and a carbon neutral source of energy [32,33]. Ammonia decomposes to produce only hydrogen and nitrogen gases. The products of ammonia-based cell operation do not evolve greenhouse gases [34]. Ammonia is easily storable and transportable and comparatively less flammable than other fuel gases [35]. Its leakages are easily detectable due to its pungent and offensive odour [36]. Apart from the carbon and nitrogen-based fuels for the fuel cells, hydrogen peroxide is also an interesting option for generation of power from liquid fuel cells. Hydrogen peroxide is produced from reduction of molecular oxygen (Fig. 13.6) and is liquid over at ambient temperature. H2O2 produced from the reduction of O2 can be used to generate electricity from fuel cells. H2O2 is a promising fuel for the fuel cells as the by-products are H2O and O2. However, the concentration of hydrogen peroxide solution to be used in fuel cells is above 80% [37]. The good thing is H2O2 can be stored and transported in gasoline storage infrastructure but caution is required as highly concentrated hydrogen peroxide decomposes on catalysis by metal. The energy generated from H2O2 decomposition has already been used in rocket propulsion [38,39]. H2O2 fuel cells can operate in the absence of O2. Modern-day H2O2 usage comes from industrial production by palladium catalyzed hydrogenation of anthaquinone followed by oxidation by O2 [40,41]. Besides methanol discussed as above, other alcohols that are potential options to be used in fuels cells are ethanol, ethylene glycol and glycerol [42,43]. Ethanol can be obtained in huge amounts from fermentation of biomass as being done industrially. Ethylene glycol can be obtained industrially from ethene through epoxidation followed by other chemical manipulations. Ethylene glycol can also be obtained from carbon monoxide as well. Glycerol can be obtained very economically as a by-product of saponification reaction as well as from biodiesel production. Electrochemical oxidation of ethanol in alkaline medium occurs according to Fig. 13.7 [43]. Similarly, ethylene glycol oxidizes electrochemically to produce EMF of 1.09 V [44].

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FIGURE 13.8 Steam methane reforming.

Besides above-mentioned solar fuels, a very important and significant fuel is hydrogen which can be obtained from splitting of water utilizing solar energy. However, presently commercialization of splitting of water using solar energy is not possible as the process is too costly. Presently, hydrogen being used for industrial processes is obtained from cracking of fossil fuels in the presence of catalysts like nickel supported over ceramic oxide (Fig. 13.8). The process is specifically called steam methane reforming, where methane or natural gas is used as a feedstock. The energy released in the process is ΔHo is 206 KJ/mol. The process of hydrogen production and its usage in combustion engines as well as in fuel cells will be taken up in the hydrogen fuel section. 13.2.1.3 Advantages of solar energy 1. Abundant amount of solar energy is available almost everywhere and also in the tropical and subtropical regions of Earth which can be effectively used for generation of power and fuels. 2. Its usage is environmental friendly and cheap. The cost is incurred on fuels for generation of power. The only cost is incurred on the infrastructure to absorb solar energy and convert solar energy to fruitful use. 3. Solar energy is used in a number of ways such as heating of water, industrial heating, residential heating, desalination of water, vehicular transport through batteries and solar fuels, generation of power with minimum production of greenhouse gases and other environmental pollution. 13.2.1.4 Disadvantages of solar energy 1. Although life of solar cells are said to be 15 20 years but in common practice its efficiency reduces even before 15 years. 2. Solar panels are not exactly ecofriendly materials as its disposal poses environmental problems because the solar panels contain toxic materials like gallium arsenide, copperindium-gallium diselenide, etc. [45]. 3. Solar panels occupy a considerable amount of space making it inconvenient to be fitted and used. Presently, the efficiency of commercial solar panels is 25% at max. The efficiency of solar cells can still be enhanced which may reduce the size of solar panels. 13.2.1.5 Conclusion Solar energy has the potential of being the replacement of fossil fuels in energy-rich regions especially the tropics. Not only it is directly used for generating electricity through concentrated solar power (CSP) and PV cells but are used for producing green fuels which can be used for vehicular transport. Owing to immense potential newer technologies are emerging to utilize the solar energy like solar arrays. Floating solar arrays are solar cells that are built over the water reservoirs, irrigation canals, remediation ponds, etc. These systems utilize areas previously left unused. Newer ideas and technologies are under R&D to capture as much as possible solar radiation and use it for as much variable uses as

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possible. As per International Renewable Energy Agency (IRENA), solar PV cells are the fastest growing renewable energy technology. The total installed capacity of solar PV reached 710 GW globally at the end of 2020.

13.2.2 Wind energy 1. Wind blows between two regions because of difference of pressure between them. The wind moves from high pressure. Introduction: Wind is movement of a certain big mass of air in a particular direction. The kinetic energy of wind has been used by the mankind since very long time. Historical evidences indicate that since Harappan civilization, 2500 BCE, wind has been used in sailing of boats to travel through seas. The kinetic energy of the wind can be utilized for generation of electricity through wind mills in sufficiently windy regions. The wind turns the blades of the big fans on the wind mills which are in turn connected to turbines to generate electricity. The greater the wind speed and denser the air, the greater is the kinetic energy and hence, larger the amount of electricity produced. At the low altitudes, that is, near the surface of the earth a low pressure region is created due to heating of the surface. The hot air from the region moves up creating a low pressure region at the surface . In order to fill the low pressure region, air from the surrounding areas moves in and thus wind is generated. The greater the difference of pressure between the high pressure region and the low pressure region, the greater would be the wind speed. The extreme case of winds are cyclones and tornadoes, which are well-known examples when wind speed exceeds 100 kmph and causes havoc in the region of low pressure area. As heating and cooling of the surface of Earth is an ongoing process and occurs alternately through the day, the wind power is considered renewable. Along the coastal regions, the direction of winds alters from day to night. During the day time, heating of the earth surface is quicker than the water of the seas and thus creating low pressure over the land masses along the coast and high pressure region over the nearby seas. Thus wind blows from the seas towards the landmass during the day time. However, during night landmass cools quickly while the sea water cools slowly and thus creating high pressure over the landmass and low pressure over the sea. Thus during the day the direction of wind is from sea to the landmass while it is reversed in the night time. Thus coastal areas are the excellent places of harnessing wind energy. However, wind blows at very high speed between the 40 N 60 N and 40 S 60 S latitudes over both the hemispheres of the globe. The winds are stronger on the southern hemisphere in the above-mentioned latitudinal regions because of the absence of landmasses and continuous stretch of ocean. 13.2.2.1 Generation of electricity Harnessing wind energy is considered to be sustainable as it is environmentally benign process and almost no harm is incurred by the environment. The winds being of natural origin are available without usage of any fuel. Wind mills/wind turbines are installed in open unpopulated area as well as in built up areas of urban regions [46]. In the built-up areas, the wind turbines can be installed on vertical axis or on horizontal axis which are essentially small wind turbines (SWT). In the former case, it may be called as vertical axis

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wind turbine (VAWT) and the latter one may be called as horizontal axis wind turbine (HAWT). The power generation from the SWT in the built-up area depends upon cut-in wind speed, flexibility of installed fans and turbines and the height at which installation has been done. Tracking of wind direction is required for HAWT for the fan of the turbine to generate maximum power. (Fig. 13.9). For installation of wind turbines in the built-up area, the technical factors like wind profile in the region and design of turbine components in order to deal with the increase turbulence of winds need to be taken into consideration. Issues of safety, noise due to vibration of the turbines, etc. are major concerns while installation of wind turbines in the urban regions. The built-up areas in the urban places have lower annual mean wind speeds due to tall buildings acting as obstacles as compared to open areas of rural regions. Thus wind turbines are installed according to safety, durability and performance standards of IEC 61400 which is a accepted international standard. The standard specifies the wind field models, occurrence of wind turbulence and other extreme events. These parameters are needed by the wind turbine manufacturers for design of turbines. The failure of the wind turbines in the urban area is due to insufficient data of the atmospheric turbulence and inappropriate design of the wind turbines. The factors that reduce the performance of the wind turbines are morphology of the built-up area which reduces the wind speeds, low mean annual wind speed, sudden change in wind direction, extreme wind speed fluctuations, atmospheric instability and unusual wind shear. The urban wind flows are affected by morphology of the buildings, relative position of the turbines, roughness of the terrain, interacting air flows, local heat flows, wind shadow areas and street canyon effect on the wind speeds. The best height for installing SWT is 30% 50% above the building height in order to avoid the turbulence effect. In order to minimize wind turbulence effect and speed of the winds, the shapes of roof tops have been evaluated for maximum power generation. The shapes of roof tops that have been evaluated are flat shaped, wedged, gabled, pyramidal, barrel shaped and spherical. The best roof top for maximum power generation is spherical shaped and barrel vaulted [47]. It has been suggested that

FIGURE 13.9 Wind turbines installed in the urban areas. Sources: From https://ases.org/wp-content/uploads/2017/ 04/urban-turbines.jpg, https://media-cldnry.s-nbcnews.com/image/upload/t_fit-1500w,f_auto,q_auto:best/msnbc/Components/ Photos/060104/060104_windpower_hmed.jpg

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rounded roof tops produces lower air turbulence intensity and high power density compared to rectangular roof tops [48]. The turbulence of the local wind regime is most importance factor in determining the energy output and durability of the turbines. Studies have shown that ambient turbulence can either enhance or decrease the turbine power output along with wind speed. In order to harness greater power from the wind, a number of wind mills are constructed in a region and all are connected to the same grid. This kind of arrangement is called wind farms, which can be categorized into two types based on location of wind farms. 1. On-shore wind farms: When wind farms are located on land, they are called onshore wind farms (Fig. 13.10). These are cheaper to construct and operate than offshore wind farms. The wind farms are built in an area where wind speeds are considerable and wind energy can be harnessed viably. The wind mills can be constructed and operated in isolation to generate a small amount of power. However, when a number of wind mills are built in bigger region and are connected to a common grid, it is called a wind farm or wind park. These wind farms may have a couple of wind mills or may have hundreds of mills spread over a very wide area. Large-scale wind farms occupy a huge land area which poses significant challenge in availability of such locations near populated areas. However, such locations are available at desolate areas but power losses during transmission poses another challenge. Usually they are located near sea shores, and other windy regions. United States and China are the leading wind power generating countries and host big wind farms. China has the largest on-shore wind farm at Gansu with a power generation capacity of 6000 MW in 2012. 2. Off-shore wind farms: When wind farms are located over the large water bodies, they are generally referred to as off-shore wind farms. These are constructed on the shallow continental shelf and are generally costly to construct and operate [49]. However, winds are more steadier and stronger over the large water bodies and the generation of electricity from off-shore wind farms becomes economically profitable.

FIGURE 13.10 On-shore windfarm. Source: From https://www.azocleantech.com/news.aspx? newsID 5 30200

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As the distance of wind farms increases from the point of consumption of electricity, the loss of power increases significantly. Thus the wind farms must be located near the consumption centres to remain economically viable. As the winds are not steady with respect to speed so the wind farm electricity must be supplemented with power from other sources as well in order to maintain a constant power supply throughout. Hydroelectricity supplements the wind power very well. On days of stronger winds, the hydroelectric power may be reduced while it may be increased on days with low wind speeds. Wind power is complementary to solar power to a certain extent on day-to-day basis. High pressure regions (i.e., low wind regions) have clear skies (i.e., sufficient solar energy), while low pressure regions (i.e., strong wind regions) have cloudy skies (i.e., insufficient solar energy). However, seasonally the solar energy remains available in ample amounts in the summers, while the winds are weaker and the situation is just reversed in the winters. 13.2.2.2 Construction of wind mills Wind mills are constructed as shown in Fig. 13.11. A big fan of two or three blades is generally constructed over a tall tower of appropriate height. The direction of the blades of the fan is kept perpendicular to the direction of the wind. The direction of the blades is adjustable so that wind blowing from any direction could be utilized for power generation. The motor of the wind mill is connected to the turbine of the generator. All the wind mills are individually connected to a common grid from where power is supplied to the consumption centres. The estimated average operational lifetime of wind mills is 20 years. Generators are the major components of wind mills which convert the mechanical energy of the wind to electrical energy. There are mainly three types of wind turbine generators: DC generators, AC synchronous generators and AC asynchronous generators [50]. AC synchronous generators are generally preferred for SWTs, while the AC asynchronous generators are used in medium to large wind turbines. China and United States are the global leaders in harnessing wind power. However, India is also catching up fast to replace its fossil fuel based power production system with renewable sources of energy like wind. Global wind atlas provided by the Technical University of Denmark along with World Bank helps in planning the construction of wind farms. Total amount of power extractable viably from the wind is considerably greater than the present usage throughout the globe and thus has huge potential to tap this renewable energy resource in future. 13.2.2.3 Advantages of wind mills 1. Generation of power from wind mills is a very low cost affair as no fuels is required during its operation. 2. Renewable and sustainable source of energy. 3. Wind farms can be built on farm lands and on ranches. The area around wind mills can be used for farming.

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FIGURE 13.11 Construction of a wind mill. Source: From https://www.istockphoto.com/vector/wind-turbine-workprinciple-with-mechanical-inner-structure-outline-diagram-gm1353539090-428607754

13.2.2.4 Disadvantages of wind mills Although power generation from wind mills is very economical and environmentally benign, it has its own disadvantages too.

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1. Wind power cannot be harnessed from anywhere. Such wind speeds are available at certain specific regions only. So wind power generation is not ubiquitous. 2. Wind speeds are not steady throughout the day and 365 days round the year. So the power generation from wind mills needs to be supplements from other sources of power as well in order to provide uninterrupted power supply with constant voltage. 3. Construction of wind mills and farms covers a lot of area and takes more area than solar PV panels. 4. Construction of the wind farms leads to destruction of wildlife due to loss of their habitat. 5. High altitude of the wind mills causes disturbance in flying aeroplanes. 6. Loss of lives of birds and insects is caused due to rotation of the blades. 7. Some minor sound pollution also happens by the operation of wind mills which may be disturbing to the nearby population and also to the animals. 13.2.2.5 Conclusion Extraction of energy from winds is possible only in areas where wind speeds are considerable and steady. This source of power generation is not as ubiquitous as solar energy. However, wind energy technologies are matured enough for its commercial application is marketable. Infact most of the renewable energy installations done in the last decade are in solar and wind energy generation. However, there lies a huge potential to be tapped fruitfully for supplementing the other renewable sources of energy and supplanting the environmentally detrimental fossil fuels. The leading nations investing in wind energy generation are China, United States and west European nations. According to IRENA, wind power generation installations have increased significantly in the last two decades. The wind power generation has increased from 7.5 GW in 1997 to 733 GW in 2018. The generation capacity has increased both in on-shore and off-shore wind power installation capacity. The power generation capacity has increased from 178 GW and 3.1 GW in 2010 and to 699 GW and 34.4 GW in 2020. Generally, the best locations for wind power generation are in remote locations.

13.2.3 Geothermal power 13.2.3.1 Introduction Geothermal energy is the heat energy obtained from deep inside the earth surface in the form of hot magma and lava. This hot magma heats up the adjoining rocks and the water trapped in those rock masses seated deep below the surface of earth. The superhot water and steam from these places below the surface of earth makes its way to the surface in the form of hot springs and geysers. This heated water and water vapour under high pressure are utilized for various purposes. The mechanism of transfer of heat from the mantle and core of the earth is brought to the surface through the convection currents of the magma. The hot magma rises and reaches the lower surface of the crust through convection currents. There it heats up the adjoining rocks along with the water trapped between the rocks. After losing heat to the rocks and water, the magma subsides below and another portion of hot magma rises and takes the place of cooled magma. This way heat from the interior of the earth is continuously brought

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to the surface of the earth. In this way, the interior of the earth is slowly cooling down over the geological timescale. The origin of heating inside the earth has a number of theories but the most acceptable theory is due to rubbing of rocks against one another under huge pressure and radioactive decay of the huge amount of radioactive substances trapped below the crust of the earth. The geothermal energy has been used since very long time in history in the form of hot water baths, having therapeutic significance as in case of hot sulphur springs, heating of homes, cooking, etc. Presently, water from hot springs is being used for heating of homes in cold regions, used in spas, industrial purposes, desalination and in agriculture besides generation of electricity. 13.2.3.2 Generation of electricity This huge energy when used to generate electricity is called geothermal electricity. The first geothermal power station was built at Larderello, Italy in 1911 [51]. Second such power plant was built in New Zealand in 1958. Later, in 1960, Pacific Gas and Electric company began geothermal power plant in United States. Global installed of geothermal energy was 14.3 GWe in 2017. As per technology roadmap for geothermal heat and power reported by International Energy Agency, the geothermal energy generation would reach 1400 TWh per year by 2050 [52] which will be about 3.5% of the total power generated at that time. As of 2017, the largest installed capacity of geothermal power generation was led by United States with 3.72 GW followed by Philippines (1.93 GW), Indonesia (1.86 GW), Turkey (1.06 GW), etc. [53]. The thermal energy of the interior of the earth is brought to the surface in the form of hot and pressurized water and also in the form of steam at the geothermal sources. These geothermal sources are generally located near the tectonic plate boundaries. Such boundaries on the earth are demarcated by Ring of Fire, that is, Circum Pacific belt. It is not only the rim of the pacific ocean rather it extends through the boundaries of continents as well. This thermal energy in the form of steam is used to drive turbines and thus generate electricity. There are various modes of power generation from the hot and pressurized steam from the geothermal resources which mainly depends upon the type of geothermal resource. Brines coming out from geothermal resources greater than 150 C are used for power generation in dry steam and flash-based power stations. When the temperature of the brine is lesser than 150 C, then enhanced geothermal techniques are used for generation of power. Otherwise temperature below 150 C is used for direct heating purposes. 13.2.3.3 Types of geothermal resources There are three types of geothermal resources based on temperature range and available form of hot water at the geothermal site [54]. All these being commercially exploited for the generation of power using dry steam plants, flash steam plants and binary cycle power station. However, other techniques of extraction of power from geothermal resources are in the R&D phase. One of the techniques that does not produce brine during extraction of thermal energy from the geothermal sites is wellbore heat exchanger technique [55]. In this technique, two co-axially fitted cylinders are inserted into the well dug for the purpose. A heat exchanger fluid, which is generally an organic fluid with lower boiling point than water, is injected through the external cylinder. As the fluid descends down, the temperature increases and it vapourizes. The organic vapour moves into the inner cylinder

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through the bottom hole and moves up with great force. This organic vapour with great energy is used to drive the turbine fitted at the surface of earth. The technique suffers from low efficiency of heat extraction compared to other steam and liquid-based geothermal power stations. However, the advantage of this technique being nonproduction of contaminated brines that are produced in other conventional geothermal power stations. Other types or conventional types of geothermal resources are as follows. 1. Vapour dominated geothermal reservoirs: The temperature range in these type of sites is 240 C 300 C. They have superheated steam stored at these sites, for example, The Geysers (United States) and Lorderello (Italy). These are only few in number globally and uses simplest technique for generation of power among geothermal power generation techniques. 2. Liquid dominated geothermal reservoir: These type of reservoirs are more common in occurrence. The temperatures at these sites are greater than 200 C. They are found near young volcanoes, for example, around Pacific ocean and in the rift zones. Flash plants are employed to generate electricity from these sites. Most wells made at these sites generate 2 10 MW of electricity. Cerro Prieto in Mexico which is a liquid dominated site generates about 750 MW of electricity up till 2013. The Salton sea field, in southern California, United States, is also a liquid dominated site and offers fair potential of generation of electricity. Lower temperature liquid dominated geothermal reservoirs have a temperature range of 120 C 200 C and requires pumps for the extraction of hydrothermal resource. These type of reservoirs are found in terrains where the heating of water occurs due to circulation of water along the faults lines placed deep down the surface as in western United States. 3. Enhanced geothermal reservoirs: These are engineered geothermal resources where the temperature of the hot water inside is relatively cooler than other two types of geothermal resources. At these sites water is injected into the reservoir wells and hot water is pumped back. For utilizing heat stored in such sites an injection well is drilled to the hot basement rock that has very little fluid content. This type of almost dry hot basement rock is sometimes referred to as hot dry rock. Water is injected at sufficient pressure through the drilled well to create fractures in the hot basement rock. A second well is drilled at some distance to the injection well in order to pump out the heated water back. Such well is called the production well. 13.2.3.4 Techniques of extraction of heat resource Based on the type geothermal reservoirs, there are mainly three types of techniques by which geothermal energy is converted to electricity. 1. Dry steam power plants: These are the simplest technique among the three. Here, steam from the hot geothermal resource is directly used to drive the turbine to generate electricity (Fig. 13.12). The steam after losing its heat condenses to liquid water which is again fed back in to injection well in order to replenish the lost water of the reservoir to some extent. First of this kind of power plant was built in Larderello, Italy, in 1904. 2. Flash steam power station: Hot water at high pressure coming out of the production well is brought to the surface by digging up wells. While coming up some of the water gets cooled, while rest remains as steam which is used to run turbines to generate

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FIGURE 13.12

plant.gif.

Dry steam power plant. Source: From https://www.eia.gov/energyexplained/geothermal/images/flash-

Flash steam power plant Flash tank

Load Turbine

Generator

FIGURE 13.13 Flash steam power plant. Source: https://www.eia.gov/energyexplained/ geothermal/images/flashplant.gif

Rock layers Production well

Injection well

electricity (Fig. 13.13). The cooled and liquified steam is again channelled back into the hot reservoir through the injection well. Most of the geothermal power plants are of this type. 3. Binary cycle power station: These geothermal power plants were first developed in USSR in 1960s. Presently, this technology is widely used worldwide. This type of power

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stations are developed at sites where the temperature of the resource is relatively lower. In this type of power plant, hot water from the hot reservoir is made to run parallel to an organic fluid with a lower boiling point than water, contained in a separate pipeline (Fig. 13.14). This process helps in exchange of heat between the hot water of the reservoir and the organic fluid of the instrument which functions as a working fluid. The hot working fluid of the generator drives the generator turbine to generate electricity. 4. Enhanced geothermal power station: In these type of power stations, the underground geothermal reservoir is fractured artificially by injection of fluid and rock simulation. Different types of hydraulic fracturing fluids have been used, such as polyallylamine [56] and supercritical CO2 [57 59]. These type of power stations are majorly of two types based on depth of the available resource. 1. Shallow depth geothermal resource: These sites have wells drilled up to a depth of 1000 to 2000 m. The temperature range of these sites is between 100 C and 300 C. These type of sites are being used for electricity production commercially. 2. Deep depth geothermal resource: The wells at these sites are drilled up to a depth of 3000 5000 m. The temperature range of the hot water at these is 300 C 600 C. Few of these sites are used for commercial production of electricity, while others are at R&D phase. Enhanced geothermal resources generate power more efficiently than other geothermal resources [60]. The first commercial production of power from enhanced geothermal power station occurred at Habanero, Australia in 2013 [61]. The concept for the development of enhanced geothermal system occurred at Los Almos national Laboratory, United States in 1974 [62]. The most reliable method of determining the location of geothermal resource is drilling the particular region and checking the temperature of the deep underground water. FIGURE 13.14

Binary cycle power plant Turbine

Load

Generator

Binary cycle geothermal plant. Source: https://www.eia.gov/energyexplained/geothermal/images/binaryplant.gif

Heat exchanger with working fluid

Rock layers Production well

Injection well

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Geothermal power stations are generally built on the boundaries of tectonic plates as the hot water resources are available over there. However, with advancement of drilling technology and evolution of binary cycle power plants the geographical spread of availability of the geothermal resources has increased hugely. A few number of sites are located in the intratectonic plate rift zones [63]. These tectonic plate boundaries and intratectonic rift zones have been used to some extent, and power plants have been developed by countries like United States, Philippines, Indonesia, etc. United States leads in terms of installed capacity with a geothermal power generation of 3700 MW as of 2020, which makes 0.4% of the total electricity produced in the country. It also accounts for 29% of the global geothermal power production. Indonesia produces 2135 MW of geothermal electricity as of 2020, which makes 3.7% of the total power produced by the country. Philippines has installed capacity of 1920 MW as of 2020, which is 27% of the total electricity produced by the country. Geothermal energy are used to supplement biomass energy production plants and solar power plants. Biomass-geothermal hybrid plants and solar-geothermal hybrid power plants have been developed to supplement the biomass power generation plants and solar power plants. 13.2.3.5 Industrial applications of underground hot water The thermal energy of the geothermal resource is used for production of electricity, cooling and direct use of heat energy. For more efficient utilization of the heat energy obtained from geothermal resource, a concept of cascade utilization of the energy is used [64]. Accordingly, the geothermal energy utilization systems are designed to generate electricity, produce cooling and use heating of the directly for several purposes. The cooling produced by the geothermal energy systems is used for cold storages, air conditioners and other refrigerations. The heat is used for fish farming, heating of swimming pools, greenhouse warming, warming for animal husbandry uses, space heating, drying of stock fish, drying and curing of cement blocks, dehydration of agricultural products, desalination, dehydration and canning of food items, digestion of paper pulp, pasteurization of milk, gold mining, etc. 13.2.3.6 Advantages of geothermal energy 1. Environmental pollution is meagre as compared to fossil fuel usage. 2. No cost is incurred on fuels so the process is very economical. The heavy investment is incurred only on establishment the power plant. 3. Power generation is sustainable and the source is renewable. 13.2.3.7 Disadvantages of geothermal energy 1. Geothermal energy is nonubiquitous in nature. It is not available everywhere and are located only near the tectonic plate boundaries and rift zones. 2. At present the level of technology to harness geothermal energy is not well developed and not well established so the large-scale commercialization of geothermal energy is not widespread. 3. The tectonic plate boundaries are prone to frequent earthquakes and therefore the geothermal power plants may always run the risk of damage.

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4. Power generation is not sustainable as it has been observed that over few decades of power generation the undersurface site of extraction of geothermal energy starts to cool down and the underground water table depletes. Rejuvenation of the site requires injection of water from outside and also the natural underground sources of water maintains the water table if left unused for some time. The undersurface magma also heats up slowly if the site is left unused for some time. 5. Greenhouse gas emission of geothermal power houses is very low as compared to fossil fuels [65] but still COx, SOx, NOx, H2S, NH3 and volatile organic matter are evolved from the geothermal heat extraction sites [66]. The proportion of the gases released to the atmosphere varies from place to place because of the composition of magma varies from place to place. 6. Along with polluting gases some toxic chemicals like mercury, antimony, bismuth and arsenic, lithium, boron, chlorine are also released in the water during the exchange of heat between water and the hot dry rock [67]. 7. Hydraulic fracturing of the basement rock involved in the process may induce earthquakes. It has been observed at Wairakei geothermal field reinjection of used water at a huge pressure induced a minor earth quake. However, reinjection of water at lower pressure produced no observable seismicity. 8. Undesirable temperature changes severely affects the aquatic life and water quality. 9. Geothermal power plant establishment takes along period in preliminary survey, exploration of site, test drilling, field development, power plant construction, its operation and management. 13.2.3.8 Conclusion Geothermal power generation can be viably obtained along the tectonic plate boundaries and with the progress of technologies it can be obtained in intraplate regions as well. These power generation systems can be very fruitfully used to supplement the other power generation systems like solar, wind and hydroelectric power projects sustainably. The technologies are matured enough to be used in order to supplant fossil fuels in certain regions of the globe. As of 2019, the global geothermal power generation capacity was 15.4 GW. Countries like Indonesia and Philippines are already meeting a significant proportion of their energy needs through geothermal energy. They have plans to ramp up their infrastructure further to increase the proportion of power generation from it. Other countries like United States, Turkey, Mexico, New Zealand and Iceland have huge potentials to obtain geothermal energy and reduce dependence on fossil fuels.

13.2.4 Wave energy 13.2.4.1 Introduction Power of waves to do some useful had been recognized since times immemorial for rowing of big boats and ships. However, presently energy of waves is being harnessed to generate electricity and desalination of water as well. Waves on water surface are generated because of the pushing/frictional force applied on the surface of water by the winds passing over. If the speed of the winds is not significantly higher than the speed of the flowing water, the waves generated will be of very low magnitude. For strong waves the

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air blowing over the surface should be significantly higher. The energy of waves depends upon speed of waves, wavelength and density of the medium. In general, the bigger waves have larger energy. The regions of earth where strong waves are found in the oceans are between 40 N 60 N and 40 S 60 S. This is due to strong winds blowing between these latitudes. The origin of strong waves is due high pressure belts in this region prevailing on the surface of the earth because air descends from the higher atmosphere between these latitudes. The waves are stronger in the southern hemisphere than the northern hemisphere between these belts because of uninterrupted stretches of water body devoid of any intervening landmasses. Till now the power of waves has not been harnessed on a significant commercial scale as has been done with solar energy, wind energy and hydroelectricity. First commercial scale wave power plant Islay LIMPET was installed on the coast of Islay, Scotland, in 2000. However, in 2008, in Portugal an experimental wave power plant was installed. 13.2.4.2 Generation of electricity In general kinetic energy, pressure difference created by waves and oscillating motion of waves are harnessed for generation of electricity. However, other modes of generating electricity are under various stages of development [68 70] and have not been commercialized yet. These devices in general are referred to as wave energy converters (WEC). Power generation from modern devices starts from Masuda device [71] which is essentially an early from of a buoy. This gets its name from a Japanese navy officer Yoshio Masuda (1925 2009), who developed a buoy with an air turbine. The device obtained energy from the oscillating motion of the waves to drive its turbine. He may be regarded as the father of modern wave energy technologies. These type of devices were deployed in large numbers in Japan by 1965 and later the same was done in United States. However, these devices being named as oscillating-wave-by-column (OCW) devices by 1978 onwards. Masuda devices (OWC) form the major class of WEC to be deployed and studied most widely among the WECs. The OCWs are still the favourite and promising devices amongst the WECs for generation of power. However, OCWs are one among a number of devices under R&D. WECs may be categorized based on following. 1. Classification based on location of deployment: The WECs may be deployed on-shore, near shore and off-shore. a. On-shore devices: As the name suggests, the devices are installed at the shore. The installation may be on a cliff or in a dam, above the water surface. The devices are easy to install and maintenance is economical. These devices can be easily integrated to a grid and are nearer to the power consumption centres. However, the waves at the shore are less energetic than the waves in open seas; therefore the power generation is lesser. b. Near shore devices: These devices are installed at a distance of a few hundreds of metres from the shore at moderate depths of around 10 25 m. These instruments are installed on seabed therefore does not require mooring devices for anchorage [72,73]. c. Off-shore devices: These are installed in deeper waters at a depths greater than 40 m. The systems may be installed on submarine structures or are floating devices while being anchored to the seabed by mooring cables. Waves at these distances from the shore are energetic so that maximum power is obtainable. However, installation and

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maintenance of the devices are costly and the system suffers from significant losses in transmission to the grid. 2. Classification based on type of power take-off system: This classification of WECs is based on the mode of extracting energy from the waves. They may be categorized into the following a. Attenuators: These devices are long structures as compared to the wavelength of the waves. The device is arranged in parallel fashion to the waves, and is thus arranged in perpendicular direction to the motion of the waves. There are a number of such devices all arranged in a row and connected to one another longitudinally. The name attenuator signifies the working principle based on which the instrument works. It attenuates the amplitude of the waves which strikes the device. b. Point absorbers: These devices are essentially Masuda devices or its modification. These are floating objects anchored to the seabed through mooring cables. It collects energy from the oscillatory motion of the waves. c. Terminators: These devices are very similar to the attenuators; however, it works by almost terminating the waves rather than just attenuating them. These are long devices arranged perpendicularly to the direction of motion of the waves. 3. Classification based on working principle: The various modes of harnessing electricity from waves are as follows: 1. Floating devices: Floating devices floats on the surface of water and utilizes movement of the device to obtain energy. The vertical oscillatory motion of water due to waves is converted into rotatory motion of the turbines and generates power. The power generation from vertical motion of the device is utilized by buoys, that is, Masuda devices. These devices are anchored to the fixed submarine surface below by mooring cables and the potential energy stored in the device due to its vertical motion with respect to the seafloor is utilized for power generation [74,75]. The lower end of the buoy is fitted with a broad piston covering a cylinder (Fig. 13.15). When the buoy rises under the effect of a wave, the piston also rises and draws water along with it in the turbine thus driving it. When the buoy moves down it pushes the water into the turbine chamber, thus driving the turbine generator and producing electricity. Many such buoys installed at a place are connected to a common grid. The power from the common grid is supplied to consumption centres. Buoys can be installed at various depths and distance from the shore. 2. Surface attenuators: Surface attenuators [76] are floating devices that use rises and falls waves to create flexing of one cylindrical section of the device with respect to another (Fig. 13.16). The flexible hinged joints that connect the several cylindrical sections to one another longitudinally drives the hydraulic pumps to generate electricity. There are a number of such surface attenuators arranged parallely to the direction of motion of waves. All the attenuators are connected to a grid and thus produces greater power. 3. Oscillating wave surge converters: These devices float on the surface of water, while the lower end is anchored to the seafloor. These structures are made up of flaps, floats and membranes which are designed to move horizontally along with the movement of waves. The floating part moves like a pendulum under the effect of wave motion. The pendulum like motion compresses and relaxes the linear piston of a generator thus generating electricity (Fig. 13.17).

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FIGURE 13.15 Buoy. Sources: From https://www.google.com/search?q 5 buoys&sxsrf 5 ALiCzsY7Kc6S41MGpHc VPHEQhreuDe9xVQ:1661983410156&source 5 lnms&tbm 5 isch&sa 5 X&ved 5 2ahUKEwjAv6PWivL5AhWzBrcAHa5nCYUQ_AUoAXoECAIQAw&biw 5 1536&bih 5 656&dpr 5 1.25#imgrc 5 Y3YUpDTNtp70gM, https://www.mdpi.com/20711050/12/6/2178.

FIGURE 13.16 Surface attenuators. Sources: From https://www.google.com/url?sa 5 i&url 5 https%3A%2F%2F http://www.researchgate.net%2Ffigure%2FWorking-principle-of-Attenuator-Pelamis-25_fig2_271949918&psig 5 AOvVaw3gZloSff6H-c74OvS6Sb9Y&ust 5 1672033716069000&source 5 images&cd 5 vfe&ved 5 0CBEQjhxq FwoTCID0sJKJlPwCFQAAAAAdAAAAABAE, https://www.mdpi.com/2071-1050/12/6/2178.

4. Overtopping devices: These are long floating devices and used to create artificial reservoir in the main water body. The water brought by waves is collected by these floating devices and an artificial lake is created (Fig. 13.18) [77,78]. This lake has higher level of water than the surrounding water body. Thus a difference of pressure is created between the artificial reservoir and the main water body. This difference of pressure is used to drive the turbine attached and generate electricity. These devices are installed either at on-shore sites or off-shore locations.

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FIGURE 13.17

Oscillating wave con-

verter device.

Sea Water “IN”

Low Head

Reservoir TG

R

am

p

Water Impoundment Floating Structure

Sea Water “OUT” through Turbine

FIGURE 13.18 Overtopping device. Source: https://www.alternative-energy-tutorials.com/wave-energy/wave-energydevices.html; http://coastalenergyandenvironment.web.unc.edu/wp-content/uploads/sites/276/2012/07/wave-drag1.jpg

5. Pressure differentials: These type of devices uses the pressure difference created by the crests and troughs of the waves to generate electricity [79]. The devices may be installed below the water surface or half submerged. Submerged pressure differential devices: These devices are installed on the seabed at some distance from the shore. When the wave crest is over the device, the device is compressed below. While under the influence of a trough the device rises up. This vertical oscillatory motion of the device is used to drive a linear generator for electricity generation. A number of such devices are connected to a grid to generate sufficient power for the consumption centres (Fig. 13.19). Half submerged devices: The devices are installed on the shore. These devices have hollow air filled chambers floating on the surface of water body. When the wave crest gets into the hollow chambers the air above the water surface is compressed which is channelled into the turbine in order to generate electricity (Fig. 13.20). When the wave trough is in the device the air is sucked back through the turbine.

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FIGURE 13.19 Submerged pressure differential device. Source: https://www.enr.com/ext/resources/Issues/ National_Issues/2016/Dec-2016/26-Dec/how_it_works2016_ENRready.jpg

13.2.4.3 Advantages of electricity from waves 1. Waves are renewable and harnessing energy from them is environmentally benign. 2. The installation of the plant is comparatively economical as compared to other nonconventional sources of energy. No cost of fuel is required during production of power. 3. WECs can generate energy 90% of the time, while the same for solar devices and wind devices is 20% 30% of the time [80].

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FIGURE 13.20 Oscillating air column devices. Source: https://media.springernature.com/lw685/springer-static/ image/art%3A10.1007%2Fs40032 021 00730 7/MediaObjects/40032_2021_730_Fig2_HTML.png

13.2.4.4 Disadvantages of electricity from waves 1. This source of energy is only available at the sea shore and in the open seas and not on the landmasses. 2. Disturbs marine life to certain extent. 3. The average power of the waves is 0.1 Hz and thus need to be raised to 50 Hz to be compatible with the general usage of electrical power. 4. The atmospheric conditions on the seas are many a times are extreme due to which protection and maintenance of the power generation system is necessary. 5. The wave energy is not uniform throughout the globe. Generally near the coasts wave energy is less, while at high seas its maximum. Also, highest wave energy is between 40 C and 60 C latitudes in both the hemispheres. Moreover, southern hemisphere is richer in wave energy as compared to the northern hemisphere. 6. Technology to harness wave energy is not well established yet. Thus commercial plants are still not popular yet.

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13.2.4.5 Conclusion WECs are at various stages of development; however, none of the wave energy installations/technologies have reached commercialization and marketable stage. The wave power generation is financially viable only along the coasts and is little farther. However, in the inland regions the wave power is not financially viable. Among the WEC technologies, only the point absorber buoy technology has reached a certain level of maturity to be funded for commercial and marketable applications.

13.2.5 Tidal energy 13.2.5.1 Introduction Tides have been known to the mankind from prehistoric times and have been used for the purpose of docking ships and sailing through shallow waters. Tidal mills were in use even in the middle ages [81]. However, the potential for generation of electricity from tidal current was foreseen for Severn estuary. Worlds first tidal power plant was established in 1966 at La Rance, France, with an installed capacity of 240 MW [82]. There have been a good number of tidal power plants installed in various countries ever since. Recently, Sihwa lake tidal power plant, South Korea, started functioning in 2011 with an output power capacity of 254 MW. It is the largest tidal power plant installed till date. Another tidal power plant, MeyGen project, with an installed capacity of 398 MW is under construction at Pentland Firth in northern Scotland [83]. Tides are vertical displacement of water observed in the large water bodies like seas, oceans, bays, etc. The effect of tides in small water bodies like ponds, lakes and rivers is too small to be observed. Tides are caused due to gravitational pull of moon and the sun. The gravitational pull of moon is greater than that of sun because of former being nearer to the earth. Roughly, tides move along with the moon with a little and variable time lag between the motion of moon and that of tides. At any given place there are two high tides and two low tides during the 24-hour duration. The two high and low tides at a place are not of equal amplitude. The magnitude/amplitude of tides vary with position of sun and moon with respect to earth (neap and spring tides). It also depends upon the distance of moon and sun from earth (perigee and apogee). The shape of coastline (bathymetry) also affects the tidal amplitude and periodicity. The high and low tides at a place are predicted by recording time of tides for a considerable length of period. The actual time and amplitude of tides depend on the above given factors along with the intensity and direction of winds along with atmospheric pressures. Tides are much more predictable and reliable than solar energy and wind energy prediction [84,85] and occur with excellent regularity. Tides are the only renewable energy source that do not obtain its energy from solar radiation. Rest all the renewable sources of energy, namely solar, wind, waves, bioenergy, hydroelectricity, etc. have their ultimate source of energy to be the solar radiation. Tides are more energetic than winds. Tides at 10 miles/h (i.e., 16 km/h) have an impact equal to wind of 90 miles/h (i.e., 140 km/h) [86].

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FIGURE 13.21

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Tidal barrage. Source: From http://tidalenergyshc.weebly.com/uploads/4/8/0/5/48051121/header_images/

13.2.5.2 Generation of electricity In recent times, tidal energy has been used to generate electricity. There are two modes by which energy of tides are used to generate electricity: kinetic energy of flowing water and potential energy of water stored behind huge barrages during the high tides [87]. Generation of electricity is not possible all along the coast. Land constrictions like straits and inlets into land speeds up the water which can be used to power turbines for generation of electricity. For economically viable generation of electricity, a sufficient tidal range is required so that stored water has the potential energy to power turbines and generate electricity. The tidal range is the difference of height of water between low tide and high tide. The efficiency of electricity generation depends upon the tidal range and tidal velocity. The greater the tidal range and greater the velocity of tides, the greater is the efficiency of generation of electricity. In general, there are two methods of harnessing tidal energy into electricity. 1. Tidal stream generator: The tidal stream generator uses the kinetic energy of the moving water of the tides to drive the turbines to generate electricity. All the coastal regions are not equally fit for using the kinetic energy. Those regions that have narrow entry and exit points for water are the best suited regions for this method of generation of electricity. The narrow entry and exit points increase the velocity of entering water and the exiting water. 2. Tidal barrage: This method of generation of electricity uses the potential energy of the stored water behind a dam. This is essentially generation of electricity by building a dam across the full width of the passage (Fig. 13.21). When the high tide water recedes during the low tide phase, water is released from the barrage over the turbines and power generation occurs. Tidal current turbines can be classified broadly into majorly three categories: horizontal axis turbines, vertical axis turbines and ducted turbines [88]. These turbines convert the

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kinetic energy of the tidal current into electricity. The tidal current technologies can be categorized broadly into six categories: horizontal axis turbines, vertical axis turbines, oscillating hydrofoils, ducted turbines, Archimedes screw and tidal kites. 13.2.5.3 Advantages of tidal power 1. It is a renewable and environmentally benign source of energy. 2. The economy cost of the process lies in the fact that investment in fuel is not required. Only investment is the initial installation of the infrastructure to generate electricity. 3. The tidal energy is more predictable and reliable than the solar energy and the wind energy. 13.2.5.4 Disadvantages of tidal power 1. This source of power is available only at certain specific sites along the coast and not at any place of the coast. 2. It kills and disturbs the marine life due to the rotating turbine. 3. Construction of barrages may change the shape of coastline within the bay or the estuary. 4. Corrosion of the metallic part of the of the device especially the turbine due to salty water of the oceans is a big issue. However, rate of corrosion may be reduced by using corrosion resistant materials like stainless steel, copper-nickel alloy, and titanium in the metallic parts of the system. 5. Leakage of fluids and other chemicals like lubricants from the system may pollute the marine life. 6. High cost of installation of the system and its maintenance is prohibiting its popularization. 7. Technology is not matured enough for its wholesale commercialization. 13.2.5.5 Conclusion Although generation of electricity from tidal energy has been in use since 1966 but its widespread commercialization has yet not taken place because of prohibitory cost of installation and maintenance. Moreover, the technology of harnessing tidal energy is still not matured enough for its popularization. However, the technology is undergoing good deal of research and development in Europe, United States, South Korea, Japan, Russia and elsewhere to use this source of renewable energy. Although it is not a huge source of energy, it can supplement the other sources of renewable energy to fulfil the local demands.

13.2.6 Hydroelectricity 13.2.6.1 Introduction Hydroelectric power is the largest and most widely used source of renewable energy being used for more than 150 years. However, the first hydroelectric power project was established in England at Northumberland in 1878 by William Armstrong. It accounts for largest source of renewable power used presently [89]. The proportion of contribution of power through hydroelectric source is around 70%, which is more than the contribution of

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power generated from rest of the renewable sources combined. Hydroelectricity makes more than 85% of the total power produced by few countries like Norway, Republic of Congo and Brazil. Hydroelectricity accounts for almost 16% of the total power produced from all other sources, namely, fossil fuels (natural gas and coal), nuclear and renewable sources [90]. In the present times, the largest hydropower projects are the Three Gorges Dam (China), Itaipu Dam (Brazil), Xiluodu Dam (China), Belo Monte Dam (Brazil) and Guri Dam (Venezuela) with installed capacity of 22.5 GW, 14 GW, 13.86 GW, 11.23 GW and 10.2 GW, respectively. 13.2.6.2 Generation of electricity Electricity is generated from river streams using the kinetic energy of the running water or the potential energy of the stored water behind a dam. The most widely used principle underlying is the generation of electricity using the potential energy of the stored water behind a dam constructed for the purpose. The stored water when released from the dam converts the stored potential energy to mechanical energy which is used to drive turbines to generate electricity. However, there are hydroelectric projects that use kinetic energy of the running water directly for driving the turbine. Power generation from a turbine depends upon the height from which the water is falling on the turbine and the volume of water falling on the turbine. The greater the height and volume of the water falling on the turbine, the greater the power generation. The dam are of varied sizes starting from very small dams to big to mega dams with power production capacity corresponding to its size. Large hydropower projects are those having generation capacity of more than 25 MW. Small power projects with generating capacity between 100 kW and 25 MW, micro power projects with generation capacity 5 KW 100 KW and pico power projects with generation capacity of less than 5 KW. Power generation from small projects are considered more ecofriendly and socially acceptable [91]. These projects need small reservoir and lesser area for installation. Thus lesser land area is submerged under the water and flora and fauna is harmed to a lesser extent [92 94]. Hydropower projects are categorized into three types based on the mode of power generation. 1. Storage type: These power projects store the running water of river in a big reservoir by construction of a dam. The stored water is allowed to fall on turbines for the generation of electricity. Most of the dam are of this type. Large and small power projects are of this type. 2. Pumped storage type: In order to meet peak demands of power, this type of dams are built. In this mode of power generation during lower demand times, excess power generated from a power project is used to pump excess water in the reservoir to another reservoir at a higher elevation. The water at higher elevation is released through the turbines during peak demand times in order to generate power just like the storage type power projects. 3. Run-of-the river type: These type of power projects use kinetic energy of the running stream to generate power. The excess power generated is wasted and cannot be stored for future use. Micro and picosized power projects are of this type.

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13.2.6.3 Advantages of hydroelectric power projects 1. Hydroelectricity is a renewable source of electricity with positive effects on environment like raising the water table in and around the reservoir. 2. The hydroelectric dam can be switched off any time in a very short notice or its production can be increased or decreased within minutes. Another advantage is that the dam can be restarted, and it achieves full production load in 10 minutes time duration which is not possible with solar, wind, nuclear and even fossil fuel based power plants. 3. The reservoir provides water for irrigation, fishing, water for household and industrial usage. It also provides picnic spots and water resorts for entertainment. 4. Small power projects are environmentally and socially more acceptable. Lesser infrastructure and land is used for its installation. 5. Countries lying in the mountainous regions like Nepal, Bhutan and Lesotho can meet almost all of their power demands from hydropower projects. 13.2.6.4 Disadvantages of hydroelectric power projects 1. Large dams have been associated with earthquakes. The water stored in the reservoirs of large dams has a correlation with occurrence of earthquake because of the shear weight of the stored water on the tectonic plates below the dam. 2. The reservoir inundates a big area in the upstream region and disturbs the habitat of wildlife and other human settlements. 3. The dam causes severe siltation in the upstream region while the downstream region gets devoid of nutrients and other minerals necessary for soil productivity and aquatic life. 4. Accidents in the dams may cause floods in the downstream area. Also during heavy rainfall when the pressure of water increases beyond endurance capacity of the dam, the water is released suddenly to save the dam. Such situations causes flash floods in the downstream regions resulting into loss of life and property. 5. In the lean period of very low rainfall the downstream river almost dries up due to scarcity of water. 6. The reservoir of the dam contains still water so the aquatic life present there dies and decomposes and releases methane into the atmosphere which is greenhouse gas. 7. Generally potential for installation of hydropower projects lies in remote regions far away from big human settlements and industrial regions and the private institutions show less interest in investing in such projects.

13.2.7 Biodiesel 13.2.7.1 Introduction Biodiesel is an alternative fuel to fossil fuels that are compatible with modern day combustion engines [95,96]. These fuels are obtained from animal fat and plant oils. Chemically biodiesels are esters of long chain fatty acids with simple alcohols like methanol, ethanol, propanol, etc. It works as a replacement of fossil fuels in the combustion engines. First biodiesel was prepared by Rudolf Diesel in 1897 from peanut oil for the

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combustion engine. Thus these engines are also called diesel engines. However, direct use of vegetable oils in ignition engines creates numerous problems due to high viscosity, high carbon deposits, etc. [97]. Various modes have been employed to improve the compatibility of the vegetable oils with the combustion engines like dilution, pyrolysis, transesterification and microemulsification. Among these methods, transesterification has emerged as the most popular mode of improving the quality of biodiesels [98]. Esterification of fatty acids and transesterification of oils/fats requires heterogeneous or homogeneous acidic or alkaline catalysts. Heterogeneous catalysts are preferred over homogeneous catalysts owing to ease of handling. Heterogeneous catalysts being easily separable from the reaction mixture thus can be reused for another catalytic cycle [99,100]. These catalysts have high catalytic activity and create lesser pollution. Nafion and amberlyst heterogeneous catalysts have already been used but have their own drawbacks. Biodiesels can be used independently or in combination with petrodiesels in various proportions in the present day combustion engines used in vehicles and elsewhere [101]. Biodiesels have been used in vehicular transport especially in Europe and United States. Besides transportation it has also been utilized in operation of machinery and marine operations [102]. Other potential uses of biodiesels are heating oil, lubricants, plasticizers and solvents. When biodiesel is used in pure form or as mixture with petrodiesels in higher than 20% of biodiesel, the combustion engines need modification for proper functioning. However, lower proportions of biodiesel may be used directly in the combustion engines. Usage of various proportions of biodiesels in combustion engines has led to higher consumption of fuel combined with higher percentage emission of NOx, and lower emission of CO, unburnt hydrocarbons and particulate matter. Biodiesel combinations with petrodiesels suffers from high viscosity and low volatility. Solidification of fatty acids and crystal formation also occurs at low temperatures which are undesirable. The fuel properties can be improved by using various combinations of alcohols with biodiesels [103,104]. Ethanol in combination with biodiesel reduces the viscosity of the fuel [105 107]. Combination of ethanol also reduces the emission of NOx and particulate matter but increases the emission of CO and hydrocarbons. Biodiesels are obtained from esterification of long chain fatty acids or transesterification of plant oils and animal fats [108]. Esterification of fatty acids can be performed in presence of homogeneous or heterogeneous catalysts. Heterogeneous catalysts like metal oxides and their derivatives are highly active and selective in the reaction. The animal fats and plant origin oils gets transesterified with simple alkyl alcohols. Quality of biodiesels depends upon the feedstock used to obtain fatty acids. There are two ways of determining the quality of biodiesels [109]. First method determines the quality through checking the physical properties of biodiesel like density, viscosity, cetane number, flash point, neutralization number, carbon residue, etc. The second method is by checking the chemical properties like chemical composition of the biodiesel, purity of biodiesel, content of alcohol, glycerol content, etc. However, still homogeneous catalysts are being used for industrial preparation of biodiesels. Recently, sulphonated carbon acid based catalysts have shown some promising results and have the potential to replace the homogeneous catalysts [110 112]. The quality of biodiesel depends on the feedstock from which it is obtained. There are more than 350 crops that bear oil and thus are potential biodiesel sources [113]. Out of these few plant oil are edible, while others are nonedible. There are four types of sources

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from which biodiesels are obtained: edible oil sources (e.g., soybean, peanut, canola, palm, sunflower), nonedible oil sources (e.g., Jatropha, Calophyllum, Moringo oleifera), animal fat (chicken fat, pork, lard, beef, tallow, poultry fat) and waste cooking oil (WCO) sources. The use of edible oil as feedstock has limited supply because of being a food stuff. The nonedible oil plants compete with agricultural crops for land usage. The animal fat is also in limited supply. The WCO is however can be obtained cheaply. The disposal of WCO is a big problem and its usage for biodiesel production solves the problem in a very profitable way. WCO are produced from household kitchens, restaurants, food processing industries etc. Around 100 million gallons/day of WCO is produced is produced in United States [114]. Japan nearly produces 0.4 0.6 million tons of WCO annually [115]. WCO production in different countries is enormous which can be used for biodiesel production [116]. 13.2.7.2 Working of biodiesel fuels B100 fuels require modification of engines of the vehicles at a big scale. However, usage of B20 or lower fuels still requires modification of the engines. Maintenance and performance issues of biodiesels machinery would be at a higher costs. However, blending of biodiesels with petrodiesels is quite easy as it can be done before supply to the retail gas stations in a simple manner. Biodiesels dissolve rubber and as a result the rubber gaskets and rubber made hoses in the combustion engines need to be replaced with of resistant material before use, for example, fluorine kautschuk material (FKM) . Despite the difficulty faced by the vehicle manufacturers in the modifications and upgradation of their vehicles government of several nations like United Kingdom, United States and other nations have brought in laws regarding compulsory use of biodiesel combination fuels in the transport vehicles. Accordingly big vehicle manufacturers have introduced modifications in their products. The combination of biodiesel with that of petrodiesels is prepared and represented as follows 1. 2. 3. 4. 5.

B100—Pure biodiesel B2% 2% Biodiesel 1 98% Petrodiesel (v/v) B5% 5% Biodiesel 1 95% Petrodiesel (v/v) B10% 10% Biodiesel 1 90% Petrodiesel (v/v) B20% 20% Biodiesel 1 80% Petrodiesel (v/v)

13.2.7.3 Properties of biodiesels Colour of the biodiesel varies from golden to dark brown depending upon the composition of biodiesel and method of its production. Biodiesels are only slightly miscible with water. These oils have higher boiling point of around 340 C to 375 C and thus have low vapour pressures. The flash point of these fuels is around 130 C as compared to petrodiesel of 52 C. The calorific value of petrodiesel is about 45 MJ/kg, while that of biodiesel is about 32.3 MJ/kg. Biodiesels are heavier than petrodiesels having specific gravities as 0.88 g/cm3 and 0.85 g/cm3 respectively. The lubrication property of biodiesel is more than petrodiesel thus increases the life of the machine. These fuels are hygroscopic in nature although being immiscible with water.

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13.2.7.4 Advantages of biodiesels 1. It is a renewable source of energy and reduces the amount of CO2 released per litre of fossil fuel used. Additionally, there is no pollution of NOx and SOx. 2. Reduces cost incurred on using fossil fuels. Additionally, usage of biodiesel increases the period for which fossil fuels will be available in future for various purposes. 3. The lubrication property of biodiesels is more than that of fossil fuels, and hence its usage increases the life of the engine. 4. Production of biodiesel is more ubiquitous than fossil fuels which has limited deposits concentrated in particular regions of the globe. Thus the prices of biodiesels would be less affected by geopolitical issues. 5. Production of biodiesels requires oil crop production like rapeseeds, canola, soybean, etc. Thus it should boost the employment in the farming sector. 6. Biodiesels can be obtained from WCO which is cheaply available. 13.2.7.5 Disadvantages of biodiesels 1. The calorific value of the biodiesel fuels is lower than fossil fuels. Hence, more fuel compared to fossil fuels is required in order to produce same amount of energy. 2. Production of biodiesels requires oil crops. Therefore agricultural land may be put to use for production of biodiesels. This may result in increased cost of food items and in extreme conditions may result in scarcity of food. 3. For converting to biodiesel-based transportation mode, the combustion engines of the vehicles would need a complete makeover thus costs of vehicles will shoot up. 4. Increases wear and tear of engines. 5. WCO is difficult to collect at one place for production of biodiesel. 13.2.7.6 Conclusion Biodiesels are an excellent option to replace or atleast reduce the use of fossil fuels. The use of biodiesel in combination with petrodiesel requires very little modification in the combustion engine infrastructures. Moreover, production of biodiesels from WCO solves the problem of disposal of WCO which is a big problem.

13.2.8 Gasohol 13.2.8.1 Introduction It is primarily a mixture of ethanol with unleaded gasoline. The percentage of ethanol in gasohol is usually 10% 15%, while the rest is gasoline. It is another biofuel being used as replacement of fossil fuel. Up to 10% ethanol in gasoline can be used in combustion engines without modification. However, above 10% ethanol combination requires modification in the engines for fuel to be compatible. These fuels are in demand as it reduces the consumption of fossil fuels along with reduced of environmental pollution [117]. The use of gasohol leads to reduced emission of CO2 and CO thus being more ecofriendly. Currently, feedstocks being used for industrial production of ethanol are food crops such as sugarcane, maize, corn and wheat. About 40% of the bioethanol production is being done from sugarcane and sugar beet. However, usage of food crops for fuel

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production may generate food crisis and inflation in food prices. Additionally, agricultural land may have to be diverted for fuel production. There is a huge potential in second generation feedstock, for example, lignin, cellulose, xylans, lignocellulose and hemicellulose [118] for ethanol production [119]. These being nonedible part of the plants may not affect the food prices or cause shortage of foods. However, conversion rate of cellulosic material into ethanol is lower than from food crop based feedstock. 13.2.8.2 Working of the fuel Presently, biomass-based fuels constitute 9% 13% of the global energy supply. In 2008, bioethanol-based fuel met almost 1.8% of the fuel demand for transportation [120]. Global bioethanol production was 100 billion litres in 2016 which is projected to rise to 134 billion litres by 2024 [121]. Presently, United States is the leading producer of bioethanol with a share of 42%, while the second position is held by Brazil with a share of 31%. Although 10% 15% ethanol in combination with 90% 85% gasoline as a fuel is more common; however, there are engines that can work on 85% ethanol and 15% gasoline combination termed as E85. The naming system for gasohol is similar to the method used for naming of biodiesels. 13.2.8.3 Advantages of gasohol 1. Ethanol-based gasohol has higher octane number and thus burns without using anticrack agents. Efficiency of the fuel is higher than the normal gasoline fuels and hence reduces the release of greenhouse gases. 2. Biofuel-based fuels can boost the agriculture-based economy and increase its employability. 3. Biofuel reduces the use of fossil fuels to certain extent. 4. The use of this biofuels off-sets some of the price rise in the fossil fuels. 5. These fuels are less affected by geopolitical issues as the availability of these fuels is wide spread as compared to availability of fossil fuels in some concentrated pockets of the world. 13.2.8.4 Disadvantages of gasohol 1. Ethanol-based fuels can damage certain parts of the combustion engines, methanolbased fuels are toxic and formaldehyde-based fuels are carcinogenic. 2. The diversion of agricultural land for production of fuels may render shortage of food for humans as well as the pets and bovines. 13.2.8.5 Conclusion Bioethanol technology is well developed and should be utilized in order to reduce the usage of fossil fuels. In Europe, Brazil and United States, this blended fuel is being used successfully and must be brought into practice in other places around the globe. However small but this effort will reduce the emission of greenhouse gases (GHGs). Technology must be developed to use E100 fuels in the combustion engines.

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13.2.9 Biogas power 13.2.9.1 Introduction Biogas is a mixture of gases with major composition of methane (60%), CO2 (38%) and H2S along with minor to negligible percentage of water vapour and other gases. The gas is used domestically as well as industrially. Primarily the das is used for lighting flames, running vehicles and producing electricity. However, the percentage composition of methane is not as much as it is found in natural gas. Therefore for operating vehicles and producing electricity, the percentage of methane (the main fuel in the gas) needs to be increased. Biogas is obtained from anaerobic decomposition of agricultural wastes, animal wastes, drainage wastes, manure wastes and other organic wastes. Biogas can be compressed after removal of CO2 and H2S to produce CNG (compressed natural gas) which are used for vehicular transport and industrial purposes. 13.2.9.2 Biogas plant Biogas plants are specially designed structures for the purpose of creating anaerobic conditions. The organic wastes from various sources are converted in to biogas (Fig. 13.22). The residue is mainly a mixture of inorganic substances which is used as an excellent manure for crops. Biogas is produced by microorganisms, for example, methanogens and sulphate reducing bacteria which are anaerobic bacteria. Biogas plant provides anaerobic conditions which are used by the methanogen to produce methane. However, the percentage of methane and carbon dioxide in a biogas sample depends upon organic matter being disposed [122]. Formation of biogas is a two-stage process wherein the first step is decomposition of the organic wastes into acidic substances by the action of acidic bacteria. In the second stage, the organic acids are acted upon by the methanogenic

FIGURE 13.22 Biogas plant. Source: From https://www.topperlearning.com/answer/explain-the-structure-of-bio-gasgobargas-plant-in-brief-with-schematic-diagram/1jd65mm

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bacteria to produce methane and CO2. The residue left after evolution of biogas is called digestate, which has both solid and liquid portions. The solid part is used as manure/ fertilizer. 13.2.9.3 Advantages of biogas 1. It is a renewable source of energy and using it as fuel leads to emission of environmentally benign substances. 2. It can be produced wherever and whenever needed from organic wastes. 3. It can be used for cooking, as a vehicular fuel and for producing electricity. 4. Biogas can be compressed in to CNG gas used for vehicular transport as well as other purposes. 13.2.9.4 Disadvantages of biogas 1. The mixture of biogas with air is highly combustible so needs care during handling. 2. It takes time to produce biogas from organic wastes. It cannot be produced in a short notice. 3. The production of biogas is not a very efficient process and the gas need to be purified before using for vehicular transport and for production of electricity. 13.2.9.5 Conclusion Biogas is an excellent fuel for household burning. This is an alternative fuel technology which can be installed at local societies specially in the rural area. It can be used to supplement other main sources of power generation. The major progress has been observed in Europe in the last three decades [123].

13.2.10 Hydrogen fuel 13.2.10.1 Introduction Hydrogen is considered as a very promising alternate fuel. It has high density of energy as compared to fossil fuels. The energy content of H2 and gasoline are 120 KJ/kg and 44 KJ/kg, respectively. Moreover, the oxidation product of hydrogen is water a highly desirable product. Hydrogen has been considered to be the fuel of the future and appropriate replacement of fossil fuels [124]. As per the recommendations of International Energy Agency (IEA), hydrogen has the potential of solving critical challenges of fuel for long haul transportation of heavy vehicles. It can meet the energy requirements of chemical, iron & steel, cement and other heavy industries. As no carbon is involved in burning hydrogen, it can very effectively solve the problem of GHG emission. It can enhance energy security. Hydrogen can be produced from water through electrolysis using energy from renewable sources like solar, wind, geothermal, etc. It can be produced, stored and transported through pipelines and by ships in various forms. Currently, hydrogen is mainly used for ammonia, fertilizer productions and oil refining industries. Energy from hydrogen has a lot of potential for use in other areas where heavy power is required like transportation, powering machinery and engineering tools, domestic use and electricity generation where it is completely absent at present. However, production of hydrogen

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from electrolysis of water is quite costly at present. Most of the hydrogen obtained industrially is from reforming of fossil fuels. Intense research is underway for efficient production, storage and distribution of hydrogen so that it can be effectively used as a fuel. The interest in hydrogen emanates from the fact that it can be made available from hydrolysis of water which is present in ample amounts. 13.2.10.2 Methods of production of hydrogen Although hydrogen is so much abundant on earth, its commercial extraction process is limited and not very efficient. The main methods of production of hydrogen gas are as follows: 1. Steam reforming: Steam reforming or steam methane reforming [125] is mixing super heated steam with natural gas (which is mainly methane) to produce synthesis gas (CO 1 H2), which is a mixture of carbon monoxide and molecular hydrogen. The process yields highest percentage of hydrogen gas from per unit mass of feedstock used amongst all the industrial processes in use currently [126]. Out of the total global production of hydrogen, almost 48% of the production comes from natural gas and 18% from coal [127]. The process is highly endothermic and occurs at temperature of 1000 C 1200 C and above (Fig. 13.23, equation 1). However, if the reaction is carried out in the presence of catalyst the reaction occurs at around 600 C 800 C (Fig. 13.23, equation 2). The preferred catalyst is nickel. However, other transition metal catalysts have been used like iron and cobalt. For the maximum production of hydrogen, an another mole of water is added to produce one more mole of hydrogen (Fig. 13.23, equation 3). The whole reaction may be represented as given in Fig. 13.23, equation 4. This reaction 4 may be called as water gas shift reaction. This reaction is highly endothermic ΔH 5 165 KJ/mol. 2. Gasification of coal: Gasification of coal is a process similar to steam reforming of natural gas process. About 18% of the hydrogen produced comes from coal. The only difference is that in gasification process coal is mixed with steam at high temperatures of around 700 C. The process results in the production of synthesis gas (CO 1 H2) along with the CO2, CH4 and H2O (Fig. 13.24, equation 1). For production of maximum amount of hydrogen, a water gas shift reaction can be performed (Fig. 13.24, equation 2). FIGURE 13.23

Steam reforming or methane steam

reforming.

FIGURE 13.24 Gasification of coal.

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3. Electrolysis of water: Electrolysis of water is carried out using energy from solar radiation, wind and other forms of renewable sources of energies as well as nonrenewable sources of energy like the fossil fuel. Out of the total production of hydrogen, only 4% is obtained from electrolysis of water. A potential difference is applied across a pair of electrodes dipped in a electrolytic cell with alkaline aqueous solution as the electrolyte. Theoretically a potential difference of atleast 1.23 V is required to carry out the reaction. But in actual practice due to over voltage problems, a little higher voltage is applied across the electrodes. The electrodes are made up of an inert material like platinum. When a potential difference is applied across the electrodes, oxidation of water occurs at the anode producing oxygen gas and 4 protons and 4 electrons from 2 moles of water (Fig. 13.25, equation 1). The electron moves through the anode to the external circuit and traces back to the cathode. The protons produced oxidation of water travels through the electrolyte solution to meet electrons coming from the external circuit at the cathode. The overall reaction may be represented as shown in Fig. 13.25, equation 3. The hydrogen obtained is used for various purposes. Besides above three methods of hydrogen production which are used industrially, there are other methods as well which are under R&D. Some of the promising methods are as follows. 4. Steam gasification of biomass and waste plastics: Hydrogen gas can be obtained from steam gasification of biomass and waste plastics [128 131]. Steam gasification of biomass yields hydrogen gas in 5% 7% by weight [132], while waste plastics yield about 10% by weight [133]. The biomass or plastic after gasification pyrolysis yields a residue called bio oil and a mixture of gases named as volatiles (Fig. 13.26). The bio oil is much more energy dense than the original biomass and can be transported at much lesser cost. The gaseous residues, that is, volatiles on catalytic reforming at 600 C 800 C, yield hydrogen. Nickel [134,135] has shown to be good catalyst among other metal catalysts. The volatile material may be pyrolysed and reformed separately or may be done in the same setup. The yield of hydrogen produced through this process is dependent of the feedstock biomass and plastic used. Pyrolysis is done at a FIGURE 13.25

FIGURE 13.26

Electrolysis of water.

Steam gasification.

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minimum temperature of 500 C which is the minimum temperature for volatilisation of the biomass or the plastic components. The catalytic reforming is done at a temperature range of 600 C 800 C. Above 800 C, the catalyst starts to become deactivated or starts to get poisoned. 5. Pyrolysis of methane: Pyrolysis of methane (natural gas) can be used to generate hydrogen [136]. The pyrolysis occurs at around 1200 C (Fig. 13.27) with ΔH 5 74.85 KJ/mol of methane. However, in the presence of catalyst it takes place at 600 C. The catalysts used for the purpose are nickel, [137,138] iron, cobalt, carbon catalysts, platinum and palladium. These are supported on Al2O3, MgO, SiO2, etc. Among the catalysts, nickel works best followed by cobalt. The energy for pyrolysis can be obtained from fossil fuels or conventional sources of energy. 6. Artificial photosynthesis: Artificial photosynthesis is the term being used for production of hydrogen in the presence of sunlight (Fig. 13.28) from electrolysis of water [139]. The process can be roughly divided into three steps. a. Using light by the catalyst for creating charge separation and transfer of the energy to the reactive centres of the catalyst. b. Transfer of electron between redox cofactors within the photosynthetic chain in the catalyst. c. Redox catalysis of water leading to generation of H2 and O2 by the dinuclear metal cluster sites. 7. Microbial electrolysis: Electrolysis of organic substrates using microbes in a electrolytic cell under a potential difference produces hydrogen gas at the cathode and substrates get oxidized at the anode [140]. The electrolysis works in the usual way by oxidizing organic matter that produces proton and electron and oxidized product of the substrate. The electron moves out to the external circuit through the anode. The proton flows towards the cathode through the electrolyte hydrogen at the cathode. At the cathode reunion of proton and the electron occurs producing hydrogen gas. The whole process occurs under a potential gradient applied across the electrodes and under normal temperature and pressure. The pH of the system is at 7. Microbial electrolysis of an acetate ion (Fig. 13.29) produces bicarbonate ion at the anode (Fig. 13.29, equation 1) and hydrogen gas at the cathode (Fig. 13.29, equation 2). The glycerol has been used as substrate to produce 0.77 mol of H2 per mole of glycerol [141]. Other substrates like lignocellulose, acetic acid, butyric acid, lactic acid, valeric acid and propanoic acid have been used. FIGURE 13.27

Methane pyrolysis.

FIGURE 13.28

Artificial photosynthesis.

FIGURE 13.29

Microbial electrolysis of

acetate ion.

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13.2.10.3 Advantages of hydrogen as fuel 1. The sources of hydrogen are abundantly available. 2. It is a clean and environment friendly fuel. 3. It can be used for cooking, in internal combustion engines, industrial usage and also for generation of electricity. 4. Its efficiency as a fuel is two to three times more than that of fossil fuels. 13.2.10.4 Disadvantages of hydrogen as fuel 1. 2. 3. 4.

It is highly inflammable. Its extraction process is still not very efficient and economical. Its storage and transportation is difficult. Currently, it is almost produced from fossil fuels which is not sustainable.

13.2.10.5 Conclusion Hydrogen as a fuel holds the highest potential among all other sources of energy from being ecofriendly and availability. However, the technologies for its production from renewable sources are not matured enough to be economically viable. Still there is a lot of R&D required in this area along with policy initiatives from the government for its promotion to be effective enough to replace fossil fuels as the primary source of energy.

13.2.11 Fuel cells 13.2.11.1 Introduction Electrochemical cells use a reaction between a fuel and an oxidizing agent to produce electrical energy are called fuel cells. Power is obtained from fuel cells by connecting external load to the pair of electrodes. The fuel most commonly employed is H2(g). However, other fuels like methanol, gasoline, natural gas, dimethyl ether, ammonia [142], etc., have also be used in fuel cells. Low temperature fuel cells (LTFC) can achieve high power efficiency if hydrogen is used as fuel. However, on using hydrocarbons as fuels the efficiency of the cells reduces significantly. High temperature fuel cells (HTFC) show high tolerance for impurities with the fuel or the oxidizer. At high temperature, the impurities like CO get converted to CO2 and is not able to poison the electrodes as seen in the SOFC. HTFCs have higher potentials of reducing the emission of GHGs even if fossil fuels are used as fuels. This is due to higher efficiency of the HTFCs. The fuel gets oxidized at the anode, and the reduction process occurs at the cathode. The positively charged ion and the negative ion flow through the electrolyte to reach the opposite electrodes. The choice of fuel to be used depends on the electrolytes being used in the cell. The power in the fuel cell is generated from the oxidation of the fuel and the oxidation products being volatile are emitted out of the cell. The same type of reaction occurs in burning of the fuel too but the withdrawable energy of the fuel is much less in burning (20% 35%) as compared to oxidation in fuels cells (60% 80%). The FCs work in the same way as the electrochemical cells; however, the only difference being the FC keeps on generating power till fuel is supplied to it. Fuels have already been used to successfully

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power residential buildings with natural gas as fuel with 60% efficiency [143,144]. They can be used for vehicular transportation, industrial powering, residential applications and commercial applications. Due to these reasons, fuel cells have been called as the energy sources of the future [145]. A single fuel cell generates too little a power to be of any practical significance so a number of fuel cells are connected in series or in parallel and the arrangement is generally called as cell stack. Although many developments have been made in fuel cells, they still have only been employed in scientific work like producing energy in space missions and have not been commercialized yet. There are practical difficulties of high temperature requirement during operation of the fuel cells and high cost incurred in its manufacture. These issues need to be addressed before commercialization of fuel cells can be done. 13.2.11.2 Working of a fuel cell Fuel cell works in almost similar fashion as electrochemical cells. It consists of a pair of oppositely charged electrodes suspended in an electrode (Fig. 13.30). Oxidation of the fuels occurs at the anode. The resulting free electron goes to the cathode through external circuit, while the cation moves through the electrolyte to reach the cathode. At the cathode recombination of free electron and cation occurs. Electrical energy is obtained from the movement of electrons through the external circuit moving under a potential gradient between the electrodes. The recombination of cation, electron and the anion can also occur at the anode depending upon the type of electrolyte being used. However, there are five types of fuel cells commonly used based on electrolytes used [146]. 1. Alkali fuel cells (AFC): These cells have some aqueous alkali working as an electrolyte, for example, KOH solution [147]. H2(g)-based fuel cells are the best examples of these types of cells where O2 is used as an oxidizing agent. However, the fuel and the oxidizer required are high purity. The anode is made up of nickel, while the cathode is made up of silver. Electrode is made up of platinum. The electrodes used are made up of platinum which is quite costly. Operating temperature in such cells is between 100 C and 120 C. The energy efficiency is 70%. The output obtained in such cells is between

FIGURE 13.30 Alkali fuel cell. Source: Self drawn

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300 W and 5 KW. The cell suffers from leakage issues. The fuel cell does not tolerate presence of carbon dioxide either in the fuel or in the oxygen. Therefore both fuel and the oxidizer should be of high purity. The presence of carbon dioxide forms carbonates in the presence of alkaline media. The carbonates (e.g., K2CO3) block the pores of the cathode irreversibly and thereby decrease the conductivity of the electrolyte. The lowering of conductivity occurs at the ambient temperatures while at higher temperature lowering of performance does not take place. Thus at ambient temperatures the low solubility of the carbonate salts is the main issue. Thus carbon dioxide poisoning of the AFCs at ambient temperatures is the biggest hurdle in commercialization. The working of the cell is shown in Fig. 13.30. 2. Molten carbonate fuel cells (MCFC): In these fuel cells, the electrolyte employed is molten alkali or alkaline salts of carbonate, for example, Na2CO3, MgCO3, Li2CO3, etc. The carbonate salts melt at above 500 C. Thus the cell works at temperatures in the range 650 C [148] and higher. The energy efficiency of such cells is in the range of 60% 80%. The power output obtained is from 2 MW to 100 MW. The electrodes are made of nickel and thus are cheap as compared to other types of fuel cells with platinum electrode. The high operating temperature of the cell protects the electrodes from getting poisoned by carbon monoxide. Due to high operating temperatures, hydrocarbon fuels get reformed under the catalytic effect of Ni used in the electrodes. Thus a number of hydrocarbon fuels may be used in MCFCs. The waste heat can be recycled to generate additional electricity or for other purposes. As noble metals are not used for the electrodes, thus MCFC operation is not as costly. However, due to high operating temperatures the starting up of the fuel cell and switching off the cell cannot be done in a short notice. The pumping of carbon dioxide at the cathode poses a big operational challenge [149]. Another drawback of MCFCs is that its operational life is short of about few thousands of hours. However, operational life time of fuel cell is expected to be 40,000 hours. In these cells anode is injected with H2(g), while cathode is pumped with O2(g) (Fig. 13.31). However, CO2 is also pumped at the cathode to make up for the loss of carbonate ions at the anode. In this cell carbonate ion moves from cathode to the anode where combination of 2 H1 and CO32- occurs and water and CO2 are evolved. CO2 is again used up for the formation of carbonate ions at the cathode. The water is expelled out of the cell. 3. Phosphoric acid fuel cell (PAFC): Concentrated phosphoric acid is used as the electrolyte in this type of cell [150]. PAFCs have been used in high-power generators. The generators are commercially successful. However, due to high cost of production and operation the interest in these cells has faded in recent times. The electrolyte is a corrosive liquid and thus reduces its competitiveness with respect to other fuel cells [151]. In these cells water pressure management is not a big issue because phosphoric acid is used as an electrolyte. PAFCs have lower energy efficiency as compared to other fuel cells [152]. The cell operates in the range 150 C 200 C with an efficiency range of 40% 80%. The outputs obtained in these type of fuel cells are in the range of 200 KW to 11 MW. The anode is pumped with H2(g), while the cathode is pumped with O2(g). The operation is similar to the alkali-based fuel cells with H2O being produces as the product at the cathode which is eliminated out (Fig. 13.32). The electrodes are made up of platinum dispersed in graphite.

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Electric load Electrons Anode (–)

Cathode (+) Oxygen

Hydrogen

CO32¯

H2(g) + CO32–

0.5O2(g) + CO2(g) + 2e¯ CO32¯

H2O(g) + CO2(g) + 2e– CO2(g)

CO2(g) + H2O(g)

Heat rejection

Carbon dioxide recovery unit

H2O(l)

FIGURE 13.31 Molten carbonate fuel cell. B9780123838605000043-f04 31 9780123838605.jpg

Source:

From

https://ars.els-cdn.com/content/image/3-s2.0-

FIGURE 13.32 Phosphoric acid fuel cell. Source: From https://img.fuelcellsworks.com/wp-content/uploads/2018/09/ technology_pem_pafc.jpg

4. Proton exchange membrane fuel cell (PEMFC): Here the electrolyte used is a solid and permeable membrane sheet of a polymer [153,154]. The polymer exchange membranes are made up of perfluorosulphonic acids, for example, Nafion, Flemion, etc. However, these polymers suffer from high cost and high fuel cross-over (i.e., fuel permeability), decreasing ionic conductivity at higher temperatures, low humidity at higher temperatures, etc. Currently, one of the major focus areas in PEMFC research is

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developing novel polymer material with high proton conductivity, durability, thermal stability, maximum power density and low fuel cross-over (i.e., low fuel permeability) and low cost. Besides polysulfonic acid polymer materials, hybrid organic-inorganic composite membranes have emerged as a promising option. These organic-inorganic composites offer better electrical properties, processability, thermal stability, chemical stability, diminished fuel permeability and high proton conductivity at high temperatures. The composite materials are highly variable in composition, and methods of modification [155 161]. Other polymer materials under development are polyether ether ketone, polyethersulfone and polybenzimidazole [162 165]. Despite challenges in PEMFCs, they have few advantages over other fuel cells of having low operating temperature, low noise, shorter starting up time, lighter in weight and high power density [166]. High temperature PEMFCs (HT-PEMFCs) operate at a higher temperature range of 160 C 180 C than conventional PEMFCs using Nafion as the polymer electrolyte operating at 80 C. HT-PEMFCs have shown higher tolerance for impurities like carbon monoxide found in fuels and oxidizers [167]. Thus they provide the opportunity of using fuel and oxidizer of lower purity level. Fuels that are used in PEMFCs are hydrogen gas, methanol and ethanol. The hydrogen gets oxidized at the anode resulting in proton and an electron (Fig. 13.33). The proton moves through the polymer electrolyte to the cathode. The electron moves through the external circuit reduces the oxygen. The combination of proton and resulting oxide at the cathode produces water which is expelled out of the cell. Operating temperature of this type of cell is low with around 80 C. The energy

FIGURE 13.33 Polymer exchange membrane fuel cell. Source: From https://www.researchgate.net/publication/ 325059721/figure/fig1/AS:625113472983040@1526050074485/Cross-sectional-view-of-polymer-electrolyte-membrane-fuelcell.png

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FIGURE 13.34 Solid oxide fuel cell. Source: From https://www.researchgate.net/publication/270172308/figure/fig1/ AS:652602610024457@1532603995692/Solid-oxide-fuel-cell-SOFC-components-principles-of-operation-and-the-corresponding.png; https://www.h2epower.net/wp-content/uploads/2020/10/sofc-1.png

efficiency is in the range 40% 50%. The outputs obtained from the operation of the cell are in quite low range of 50 250 KW. However, platinum is used in both the electrodes. 5. SOFC: The electrolyte used here is solid zirconium oxide or calcium oxide. H2(g) is pumped at the anode which undergoes oxidation, while O2(g) is pumped at the cathode which undergoes reduction (Fig. 13.34). The oxygen after reduction at the cathode and the resulting oxide ions moves through the electrolyte to reach the anode. Recombination of the anion and cation occurs at the anode and water (figure) is produced as the product which gets eliminated out [168]. In this type of cell, both anion and cation can flow through the electrolyte and thus increases the fuel diversity. Besides hydrogen gas being used as fuel, hydrocarbons also can be used as fuel. When hydrocarbons are used as fuel, due to high temperature in the cell and presence of nickel at the anode, steam reforming of hydrocarbons occurs on its own. The byproduct CO produced from steam reforming is consumed in the cell. Thus the anode is saved from being poisoned [169,170]. The energy efficiency of the cell is about 60% with an output of only 100 KW. The operating temperature is about 700 C 1000 C. SOFCs with ceramic oxide-alkaline earth metal carbonate as electrolyte operate at lower temperature of 300 C 700 C with excellent electrolyte ionic conductivity [171 174]. Based on the geometry, SOFCs can be categorized into several groups of which two major groups are planar and tubular. Tubular SOFCs have few advantages of faster start-up, easier sealing and better thermal cycling [175,176]. However, tubular SOFCs have their own drawbacks of lower power density and higher internal resistance. In order to reduce internal resistance and increase the power density, the diameter of the tubular structure is reduced to few millimetres or even lesser to make microtubular SOFC (MT-SOFC) [180]. The MT-SOFC can be heated from outside in order to reach the operating temperature in 120 seconds. Thus MT-SOFCs are more time efficient than traditional SOFCs [181]. The mechanical strength of the MT-SOFC is greater than other SOFC, and its strength increases with an increase in the wall thickness to the diameter of the tubule.

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13.2.11.3 Advantages of a fuel cell 1. Low or zero emissions of greenhouse gases. 2. High energy efficiency of fuel cells has attracted a lot of research interest. 3. A number of fuels can be employed like H2, methanol, gasoline, ether, ammonia, etc. for the generation of electricity. 4. It can operate over a very long duration without voltage fluctuations. 5. It has a long active life. 6. It can be constructed on varied number of sizes. 7. It operation does not create sound pollution. It operates without making noise or other disturbances. 8. Fuel cells have been used for commercial, residential and industrial primary power supply and also as backup power. 9. FCs can be employed to power generation from mW to MW range for cell phones, laptops, transportation to industrial power supply. 10. FCs offer higher energy efficiency than other technologies of energy. 11. PEMFC and SOFC have reached the stage of commercialization but popularity among entrepreneurs is not seen because these are not yet marketable. a. SOFCs offer greater flexibility in terms of multiple fuel usage, operating temperatures, cell stock design and fabrication. 13.2.11.4 Disadvantage of a fuel cell 1. It has not been able to be commercialized yet even after lot of research. Although H2, O2-based fuels cells have been used in space mission to power up instruments and produce pure water for drinking and other uses by the astronauts. 2. Its operating temperature are quite high to very high for use at home. 3. It is still quite costly to construct fuel cells. 4. The purity of fuels and the oxidizing agents required are quite high which is a big hurdle in its popularity and acceptance. 5. Diminishing of performance of FCs is a major hurdle in its widespread commercialization. 13.2.11.5 Conclusion Fuel cells have emerged as an extremely wide range of power source. They have potential to supply power to cell phones to big machines. They may be used for power back up system, residential power supply, industrial power supply and commercial power supply. However, PEMFCs and SOFCs have emerged as the most promising fuel cells because of their solid electrolyte, and thus no issues of leakage. The only major drawback is the temperature of operation which is substantially high for safe use at residential places as well as homes. Also LTFCs suffer from the requirement of highly pure fuels and oxidizer needs.

13.3 Conclusion The above discussion about green energy technologies and green fuels makes it clear that all the forms and sources of renewable energies reduce the emission of greenhouse

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gases. However, none of forms of these sources of energy can singly meet all the energy needs of humans. They are also not ubiquitous and thus are not available everywhere and all the time. The wind energy, solar energy, geothermal energy, hydroelectric energy, wave energy and tidal energy are localized and thus cannot be obtained at any desired location. The sources of energy like biodiesel, gasohol and biogas are limited by their scale of production and also their usage produces greenhouse gases. The usage of nuclear energy may seem inexhaustible over a few hundreds of years but a longer sustenance of this fuel is not feasible due to its availability. Moreover, nuclear fuel generates radioactive residues and by-products whose disposal poses another serious threat to the environment. However, hydrogen as a gaseous fuel and also in fuel cell appears to be a promising viable source of energy over a very long period of time. However, overdependence on a particular source of energy may be counterproductive in a number of ways. Therefore a prudent mix of varied sources of renewable energy seems to be a viable option for a very long sustenance.

References [1] H.A. Maddah, V. Berry, S.K. Behura, Biomolecular photosensitizers for dyesensitized solar cells: recent developments and critical insights, Renew. Sustain. Energy Rev. 121 (2020) 109678. Available from: https:// doi.org/10.1016/j.rser.2019.109678. [2] Clean fuel: Defining clean fuels and technologies (who.int) (2023). [3] S. Nathan, Lewis, Science 315 (2007) 798 801. [4] Energy usage from solar energy: solar-fuels-2012.pdf (rsc.org), 2012. [5] Electricity from sunlight: https://www.energy.gov/eere/solar/how-does-solar-work#:B:text 5 Solar% 20technologies%20convert%20sunlight%20into,in%20batteries%20or%20thermal%20storage [6] ,https://news.energysage.com/what-is-the-power-output-of-a-solar-panel/ . (2021). [7] D.M. Chapin, C.S. Fuller, G.L. Pearson, J. Appl. Phys. 25 (1954) 676 677. [8] D. Devadiga, M. Selvakumar, P. Shetty, M.S. Santosh, J. Power Sources 493 (2021) 229698. Available from: https://doi.org/10.1016/j.jpowersour.2021.229698. and references cited therein. [9] J. Li, R. Xia, W. Qi, X. Zhou, J. Cheng, Y. Chen, et al., J. Power Sources 485 (2021) 229313. Available from: https://doi.org/10.1016/j.jpowsour.2020.229313. [10] C. Clement Raj, R. Prashanth, J. Power Sources 317 (2016) 120 132. [11] U.A. Charles, M.A. Ibrahim, M.A.M. Teridi, J. Power Sources 378 (2018) 717 731. [12] J. Chen, X. Cia, D. Yang, D. Dong, J. Wang, J. Jiang, A. Ma, S. Lv, M.Z. Hu, C. Ni, J. Power Sources 355 (2017) 98 133. [13] Ministry of New and Renewable energy, India: (2023). Available from: https://mnre.gov.in [14] International Solar Allainance, (2023). Available from: https://isolaralliance.org/ [15] V. Balzani, G. Pacchioni, M. Prato, A. Zecchina, Rendiconti Lincei. Scienze Fisiche e Naturali 30 (2019) 443 452. [16] E.S. Andreiadis, M. Chavarot-Kerlidou, M. Fonticave, V. Artero, Potochem. Photobiol. 87 (2011) 946 964. [17] K.P. Shadangi, K. Mohanty, Fuel 117 (part A) (2014) 372 380. [18] D. Pradhan, et al., Energy Convers. Manag 108 (2016) 529 538. [19] V. Chintala, Renew. Sustain. Energy Rev. 90 (2018) 120 130. [20] A. Francis, S. Shanmuga Priya, S. Harish Kumar, S. Sudhakar, M. Tahir, J. CO2. Util. 47 (2021) 101515. [21] N. Shehzad, M. Tahir, K. Johri, T. Murugesan, M. Hussain, J. CO2 Util. 26 (2018) 98 122. [22] S. Das, W.M.A. Wan Daud, RSC Adv. 4 (2014) 20856 20893. [23] J. Kim, E.E. Kwon, J. CO2 Util. 33 (2019) 72 82. [24] J.L. White, M.F. Baruch, J.E. Pander, Y. Hu, I.C. Fortmeyer, J.E. Park, et al., Chem. Rev. 115 (23) (2015) 12888 12935. [25] X.X. Chang, T. Wang, J.L. Gong, Semicond. Semimet. 97 (2017) 429 467.

Green Chemistry Approaches to Environmental Sustainability

References

[26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45] [46] [47] [48] [49]

[50] [51]

[52] [53] [54] [55] [56] [57] [58] [59] [60] [61] [62] [63] [64]

309

S. Fukuzumi, Joule 1 (2017) 1 50. S.K. Singh, X.-B. Zhang, Q. Xu, J. Am. Chem. Soc. 131 (2009) 9894 9895. S.K. Singh, Q. Xu, J. Am. Chem. Soc. 131 (2009) 18032 18033. J. Wang, X.-Bo Zhang, Z.-L. Wang, L.-M. Wang, Y. Zhang, Energy Environ. Sci. 5 (2012) 6885 6888. J.K. Niemeier, D.P. Kjell, Org. Process. Res. Dev. 17 (2013) 1580 1590. A. Klerke, C.H. Christensen, J.K. Nørskov, T. Vegge, J. Mater. Chem. 18 (2008) 2304 2310. R. Lan, J.T.S. Irvine, S. Tao, Energy Environ. Sci. 5 (2012) 6278 6289. T.E. Bell, L. Torrente-Murciano, Top. Catal. 59 (2016) 1438 1457. S.F. Yin, B.Q. Xu, X.P. Zhou, C.T. Au, Appl. Catal. A. Gen. 277 (2004) 1 9. M. Ni, M.K.H. Leung, Int. J. Energy Res. 33 (2009) 943 959. A. Afif, N. Radenahmad, Q. Cheok, S. Shams, J.H. Kim, A.K. Azad, Renew. Sustain. Energy Rev. 60 (2016) 822 835. S. Fukuzumi; Biochimica et Biophysica Acta (BBA)-Bioenergetics, 2016, 1857 (5), 604 611. Available from: https://doi.org/10.1016/j.bbabio.2015.08.012. S. Bonifacio, G. Festa, A.R. Sorge, J. Propul. Power 29 (2013) 1130 1137. B. Li, M. Jonsson, M. Algotsson, J. Bood, Z.S. Li, O. Johansson, et al., Proc. Combust. Inst. 34 (2013) 3573 3581. J.M. Campos-Martin, G. Blanco-Brieva, J.L.G. Fierro, Angew. Chem., Int. Ed. 45 (2006) 6962 6984. J. Garcia-Serna, T. Moreno, P. Biasi, M.J. Cocero, J. P. Mikkolab, T.O. Salmi, Green. Chem. 16 (2014) 2320 2343. C. Bianchini, P.K. Shen, Chem. Rev. 109 (2009) 4183 4206. L. An, T.S. Zhao, J. Power Sourses 341 (2017) 199 211. L. An, R. Chen, J. Power Sources 329 (2016) 484 501. Dangerous chemicals in solar PV cells: (2013). Available from: https://www.ucsusa.org/resources/environmental-impacts-solar-power. A. KC, J. Whale, T. Urmee, Urban wind conditions and small wind turbines in the built environment: A review, Renew. Energy (2018). Available from: https://doi.org/10.1016/j.renene.2018.07.050. I. Abohela, N. Hamza, S. Dudek, Renew. Energy 50 (2013) 1106 1118. A.-S. Yang, Y.-M. Su, C.-Y. Wen, Y.-H. Juan, Appl. Energy 171 (2016) 213 236. D.J. Willis, C. Niezrecki, D. Kuchma, E. Hines, S. Arwade, R.J. Barthelmie, et al., Wind energy research: stateof-the-art and future research directions, Renew. Energy (2018). Available from: https://doi.org/10.1016/j. renene.2018.02.049. J.F. Manwell, J.G. McGowan, A.L. Rogers, Second ed., Wind Energy Explained: Theory, 1570 Design and Application, xii, Wiley, Chichester, U.K., 2009, p. 689. S.-Y. Pan, M. Gao, K.J. Shah, J. Zheng, S.-L. Pei, P.-C. Chiang, Establishment of enhanced geothermal energy utilization plans: barriers and strategies, Renew. Energy (2018). Available from: https://doi.org/10.1016/j. renene.2018.07.126. IEA, Technology Roadmap - Geothermal Heat and Power, 715, International Energy Agency, Paris, France, 2011. BP, BP Statistical Review of World Energy: Renewable Energy, in: BP p.l.c. (Ed.) UK, 2018. Geothermal power plants: Geothermal Power Plants -. U.S. Energy Information Administration (EIA).pdf. 2022. C. Alimonti, E. Soldo, D. Bocchetti, D. Berardi, THE Wellbore heat exchangers: a technical review, Renew. Energy (2018). Available from: https://doi.org/10.1016/j.renene.2018.02.055. H. Shao, S. Kabilan, S. Stephens, N. Suresh, A.N. Beck, T. Varga, et al., Geothermics 58 (2015) 22 31. J.B. Randolph, M.O. Saar, Geophys. Res. Lett. 38 (10) (2011). n/a-n/a. J. Biagi, R. Agarwal, Z. Zhang, Energy 86 (2015) 627 637. F.-Z. Zhang, R.-N. Xu, P.-X. Jiang, Appl. Therm. Eng. 99 (2016) 1277 1285. X. Song, Y. Shi, G. Li, R. Yang, G. Wang, R. Zheng, et al., Appl. Energy 218 (2018) 325 337. D. Chen, D. Wyborn, GRC Trans. 33 (2009) 159 164. P. Olasolo, M.C. Jua´rez, M.P. Morales, S. DAmico, I.A. Liarte, Renew. Sustain. Energy Rev. 56 (2016) 133 144. Y. Feng, X. Chen, X.F. Xu, Renew. Sustain. Energy Rev. 33 (2014) 214 223. C. Rubio-Maya, V.M. Ambrı´z Dı´az, E. Pastor Martı´nez, J.M. Belman-Flores, Renew. Sustain. Energy Rev. 52 (2015) 689 716.

Green Chemistry Approaches to Environmental Sustainability

310 [65] [66] [67] [68] [69] [70] [71] [72] [73] [74] [75] [76] [77] [78] [79] [80] [81] [82] [83] [84] [85] [86] [87] [88] [89] [90] [91] [92] [93] [94] [95] [96] [97] [98] [99] [100] [101] [102] [103] [104] [105] [106] [107] [108] [109]

13. Green energy and green fuels technologies

A. Kagel, K. Gawell, Electricity J. 18 (7) (2005) 90 99. V.G. Gude, Renew. Sustain. Energy Rev. 57 (2016) 1038 1065. B.J. Purnomo, T. Pichler, J. 851 Volcanology Geotherm. Res. 285 (2014) 47 59. Electricity from Wave energy: Wave power -. U.S. Energy Information Administration (EIA).pdf, 2022. A.F.O. Falcao, J.C.C. Henriques, Renew. Energy (2015) 1 34. Available from: https://doi.org/10.1016/j. renene.2015.07.086. I. Lo´pez, J. Andreu, S. Ceballos, I.M. de Alegrı´a, I. Kortabarria, Renew. Sustain. Energy Rev. 27 (2013) 413 434. A. Falcao, Renew. Sustain. Energy Rev. 14 (2010) 899 918. B. Drew, A. Plummer, M. Sahinkaya, J. Power Energy 223 (2009) 887 902. B. Czech, P. Bauer, IEEE Indust. Elec. Mag. 6 (2) (2012) 4 16. J.P. Kofoed, P. Frigaad, E. Friis-Madsen, H.C. Sorensen, Renew. Energy 31 (2) (2006) 181 189. Bouys: Buoy_Seabased wave technology.pdf Modes of generation of electricity from waves: Wave _ Tethys_electricity generation devices.pdf D. Vicinanza, L. Margheritini, J.P. Kofoed, M. Buccino, Energies 5 (2) (2012) 193 226. A. kurniawan, D. Greaves, J. Chaplin, Proc. R. Soc. A 470 (2014) 20140559. R. Pelc, R.M. Fujita, Mar. Policy 26 (2002) 471 479. S.P. Neill, A. Angeloudis, P.E. Robins, I. Walkington, S.L. Ward, I. Masters, et al., Renew. Energy (2018). Available from: https://doi.org/10.1016/j.renene.2018.05.007. R.H. Charlier, Renew. Sustain. Energy Rev. 11 (9) (2007) 2032 2057. M. Nachtane, M. Tarfaoui, I. Goda, M. Rouway, Renew. Energy 157 (2020) 1274 1288. Y. Dai, Z. Ren, K. Wang, W. Li, Z. Li, W. Yan, IEEE Trans. Sustain. Energy 9 (2018) 168 177. Available from: https://doi.org/10.1109/TSTE.2017.2719042. J. Domenech, T. Eveleigh, B. Tanju, Renew. Sustain. Energy Rev. 81 (2018) 723 730. Available from: https://doi.org/10.1016/j.rser.2017.07.063. Alternative Energy Tutorials, Tidal Energy, https://www.alternative-energy-tutorials.com/tidal-energy/ tidal-energy.html, 2023. M.I. Yuce, A. Muratoglu, Renew. Sustain. Energy Rev. 43 (2015) 72 82. Available from: https://doi.org/ 10.1016/j.rser.2014.10.037. M.J. Khan, G. Bhuyan, M.T. Iqbal, J.E. Quaicoe, Appl. Energy 86 (2009) 1823 1835. Solar-fuels & Technologies-IEA, (2022). Available from: https://www.iea.org/fuels-and-technologies/solar. M. Bilgili, H. Bilirgen, A. Ozbek, F. Ekinci, T. Demirdelen, Renew. Energy 126 (2018) 755 764. A.K. Sharma, N.S. Thakur, Renew. Sustain. Energy Rev. 80 (2017) 679 693. S. Tahseen, B.W. Karney, Renew. Energy 67 (2017) 225 234. V. Ratna Reddy, J.I. Uitto, D.R. Frans, N. Martin, Energy Policy 34 (2006) 4069 4080. D. Kumar, S.S. Katoch, Renew. Energy 93 (2016) 599 607. A. Krishnasamy, K.R. Bukkarapu, Fuel 302 (121085) (2021) 1 29. A. Gautam, P.R. Bhagat, S. Kumar, D.S. Patle, Chem. Eng. Res. Des. 174 (2021) 365 385. F. Motasemi, F.N. Ani, Renew. Sustain. Energy Rev. 13 (9) (2009) 2205 2224. C. Enweremadu, M. Mbarawa, Renew. Sustain. Energy Rev. 13 (9) (2009) 2205 2224. K. Ngaosuwan, J.G. Goodwin, P. Prasertdham, Renew. Energy 86 (2016) 262 269. L. Wei, C.S. Cheung, Z. Ning, Energy (2018). Available from: https://doi.org/10.1016/j.energy.2018.05.049. H.M. Mahmudul, F.Y. Hagos, R. Mamat, A.A. Adam, W.F.W. Ishak, R. Alenezi, Renew. Sustain. Energy Rev. 72 (2017) 497 509. M.S.M. Zaharin, N.R. Abdullah, G. Najafi, H. Sharudin, T. Yusaf, Renew. Sustain. Energy Rev. 79 (2017) 475 493. M. Lapuerta, J. Rodrı´guez-Ferna´ndez, D. Ferna´ndez-Rodrı´guez, R. Patin˜o-Camino, Fuel 199 (2017) 332 338. H. Liu, C.-F. Lee, M. Huo, M. Yao, Energy Fuels 25 (2011) 1837 1846. P.V. Bhale, N.V. Deshpande, S.B. Thombre, Renew. Energy 34 (2009) 794 800. L. Zhu, C.S. Cheung, W.G. Zhang, Z. Huang, Fuel 90 (2011) 1743 1750. Z. Zailan, M. Tahir, M. Jusoh, Z.Y. Zakaria, Renew. Energy 175 (2021) 430 452. P.D. Rocha, L.S. Oliveira, A.S. Franca, Renew. Energy 143 (2019) 1710 1716. W.-Y. Lou, M.-H. Zong, Z.-Q. Duan, Bioresour. Technol. 99 (18) (2008) 8752 8758. B.L. Oliveira, V. Teixeira da Silva, Catal. Today 234 (2014) 257 263.

Green Chemistry Approaches to Environmental Sustainability

References

[110] [111] [112] [113] [114] [115] [116] [117] [118] [119] [120] [121] [122] [123] [124] [125] [126] [127] [128] [129] [130] [131] [132] [133] [134] [135] [136] [137] [138] [139] [140] [141] [142] [143] [144] [145] [146] [147] [148] [149] [150] [151] [152]

311

M.F. Othmana, A. Adama, G. Najafic, R. Mamat, Renew. Sustain. Energy Rev. 80 (2017) 694 709. A.B. Chhetri, K.W. Islam, Energies 1 (1) (2008) 3 18. Z. Utlu, Energy Sources, Part. A: Recovery, Util. Env. Eff. 29 (14) (2007) 1295 1304. Z. Yaakob, et al., Renew. Sustain. Energy Rev. 18 (2013) 184 193. F. Akram, Iu Haq, W. Imran, H. Mukhtar, Renew. Energy (2018). Available from: https://doi.org/10.1016/ j.renene.2018.01.095. H. Long, X. Li, H. Wang, J. Jia, Renew. Sustain. Energy. Rev. 26 (2013) 344 352. E. Derman, R. Abdulla, H. Marbawi, M.K. Sabullah, Renew. Energy (2018). Available from: https://doi. org/10.1016/j.renene.2018.06.003. S. Bringezu, H. Schu¨tz, M. OBrien, L. Kauppi, R.W. Howarth, J. McNeely; Towards sustainable production and 625 use of resources: Assessing biofuels. UNEP; http://www.unep.org/PDF/Assessing_Biofuels.pdf. 2009. World Bioenergy Association, WBA Global Bioenergy Statistics, 2017 http://www.worldbioenergy.org/ global-bioenergy-statistics. M. Negri, J. Bacenetti, A. Manfredini, D. Lovarelli, M. Fiala, T.M. Maggiaore, et al., Biomass Bioenergy 67 (2014) 339 346. C. Ingrao, J. Bacenetti, J. Adamczyk, V. Ferrante, A. Messineo, D. Huisingh, Renew. Energy 136 (2019) 296 307. The Future of Hydrogen, IEA, June, 2019; https://www.iea.org, https://www.iea.org/topics/hydrogen/. M. Msheik, S. Rodat, S. Abanades, Energies 14 (2021) 3107. A. Aba´nades, Agron. Res. 10 (2012) 11 16. L.S. Gartzen Lopez, E. Fernandez, M. Cortazara, A. Arregi, M. Olazar, J. Bilbao, Energy & Fuels (2021). Available from: https://doi.org/10.1021/acs.energyfuels.1c01666. H. Balat, E. Kirtay, Int. J. Hydrog. Energy 35 (2010) 7416 7426. S. Rezania, M.F.M. Din, S.M. Taib, J. Sohaili, S. Chelliapan, H. Kamyab, et al., Int. J. Hydrog. Energy 42 (2017) 20955 20969. J. Karl, T. Pro¨ll, Renew. Sustain. Energy Rev. 98 (2018) 64 78. P.T. Williams, Waste Biomass Valoriz. 12 (2021) 1 28. A. Molino, S. Chianese, D.J. Musmarra, J. Energy Chem. 25 (2016) 10 25. A. Erkiaga, G. Lopez, M. Amutio, J. Bilbao, M. Olazar, Fuel 109 (2013) 461 469. F. Huang, R. Wang, C. Yang, H. Driss, W. Chu, H. Zhang, J. Energy Chem. 25 (2016) 709 719. L. Santamaria, A. Arregi, J. Alvarez, M. Artetxe, M. Amutio, G. Lopez, et al., J. Anal. Appl. Pyrolysis 136 (2018) 222 231. N. Sa´nchez-Bastardo, R. Schlo¨gl, H. Ruland, Ind. Eng. Chem. Res. 60 (2021) 11855 11881. M. Pudukudy, Z. Yaakob, Q.M. Jia, M.S. Takriff, N. J. Chem. 42 (18) (2018) 14843 14856. S. Schneider, S. Bajohr, F. Graf, T. Kolb, ChemBioEng Rev. 7 (5) (2020) 150 158. E.S. Andreiadis, M. Chavarot-Kerlidou, M. Fontecave, V. Artero, Photochem. Photobiol. 87 (2011) 946 964. A. Kadier, Y. Simayi, M.S. Kalil, P. Abdeshahian, A.A. Hamid, Renew. Energy 71 (2014) 466 472. S. Sakai, T. Yagishita, Biotechnol. Bioeng. 98 (2007) 340 348. L.v anBiert, M. Godjevac, K. Visser, P.V. Aravind, J. Power Sources 327 (2016) 345 364. R. Payne, J. Love, M. Kah, ECS Trans. 25 (2) (2009) 213 219. H. Patel, T. Woudstra, P. Aravind, Fuel Cell 12 (6) (2012) 1115 1128. A.B. Stambouli, E. Traversa, Renew. Sustain. Energy Rev. 6 (3) (2002) 295 304. M. Winter, R.J. Brodd, Chem. Rev. 104 (2004) 4245 4270. A. Tewari, V. Sambhy, M. Urquidi Macdonald, A. Sen, J. Power Sources 153 (2006) 1 10. V. Das, S. Padmanaban, K. Venkitusamy, R. Selvamuthukumaran, F. Blaabjerg, P. Sianoe, Renew. Sustain. Energy Rev. 73 (2017) 10 18. A. Arshada, H.M. Ali, A. Habib, M.A. Bashir, M. Jabbal, Y. Yan, Therm. Sci. Eng. Prog. 9 (2019) 308 321. H. Hirata, T. Aoki, K. Nakajima, J. Power Sources 199 (2012) 110 116. S. Wang, S.P. Jiang, Natl. Sci. Rev. 4 (2017) 163 166. R.K. Pachauri, Y.K. Chauhan, Renew. Sustain. Energy Rev. 43 (2015) 1301 1319. Y. Liu, W. Lehnert, H. Janβen, R.C. Samsun, D. Stolten, J. Power Sources 311 (2016) 91 102. D.J. Kim, M.J. Jo, S.Y. Nam, J. Ind. Eng. Chem. 21 (2015) 36 52. M.M. Ayad, A.A. El-Nasr, J. Stejskal, J. Ind. Eng. Chem. 18 (2012) 1964 1969.

Green Chemistry Approaches to Environmental Sustainability

312 [153] [154] [155] [156] [157] [158] [159] [160] [161] [162] [163] [164] [165] [166] [167] [168] [169] [170] [171] [172] [173] [174] [175] [176]

13. Green energy and green fuels technologies

T.H. Liou, H.S. Lin, J. Ind. Eng. Chem. 18 (2012) 1428 1437. Y.G. Lee, C.Y. Park, K.H. Song, S.S. Kim, S.G. Oh, J. Ind. Eng. Chem. 18 (2012) 744 751. S.M. Park, Y.W. Lim, C.H. Kim, D.J. Kim, W.J. Moon, J.H. Kim, et al., J. Ind. Eng. Chem. 19 (2013) 712 719. M. Khajenoori, M. Rezaei, B. Nematollahi, J. Ind. Eng. Chem. 19 (2013) 981 986. S.M. Hosseini, S.S. Madaeni, A. Zendehnam, A.R. Moghadassi, A.R. Khodabakhshi, H. Sanaeepur, J. Ind. Eng. Chem. 19 (2013) 854 862. S.J. Peighambardoust, S. Rowshanzamir, M. Amjadi, Int. J. Hydrog. Energy 35 (2010) 9349 9384. O. Tongzhai, S.J. Oh, Membr. J. 16 (2006) 9 15. S.J. Lee, N.D. Quam, J.M. Hwang, S.D. Lee, H.G. Kim, H.J. Lee, et al., J. Ind. Eng. Chem. 12 (2006) 175 183. S.K. Oh, H.Y. Hwang, H.J. Kim, S.Y. Nam, Membr. J. 20 (2010) 159 168. K.K. Lee, T.H. Kim, T.S. Hwang, T.S. Hong, Membr. J. 20 (2010) 278 289. W.R.W. Daud, R.E. Rosli, E. Majlan, S.A.A. Hamid, R. Mohamed, Renew. Energy (2017). Available from: https://doi.org/10.1016/j/renene.2017.06.027. Y. Liu, W. Lehnert, H. Janβer, R.C. Samsun, D. Stolten, J. Power Sources 311 (2016) 91 102. X. Zhang, Y. Jin, D. Li, Y. Xiong, J. Power Sources 506 (2021) 230135. B.B. Skabelund, H. Nakamura, T. Tezuka, K. Maruta, J. Ahn, R.J. Milcarek, et al., Sources 477 (2020) 229007. M. Ab Rahman, M.H.D. Othman, Y. Wibisono, Z. Harem, A.F. Omar, H.A. Shabri, et al., Int. J. Energy Res. 45 (2020) 2837 2855. Y.S.Y. Wang, N. Cai, X. Ye, S. Wang, ECS Trans. 68 (2015) 2237 2243. R. Raza, M.A. Ahmad, J. Iqbal, N. Akram, Z. Gao, S. Javed, et al., Int. J. Energy. Res. 38 (2014) 524 529. L. Zhang, R. Lan, C.T.G. Petit, S. Tao, Int. J. Hydrog. Energy 35 (2010) 6934 6940. I.A. Amar, R. Lan, C.T.G. Petit, V. Arrighi, S. Tao, Solid. State Ion. 182 (2011) 133 138. W. Kong, W. Zhang, S. Zhang, Q. Zhang, S. Su, Int. J. Energy Res. 41 (2016) 16173 16180. M. Ab Rahman, M.H.D. Othman, H. Fansuri, Z. Harun, A.F. Omar, H.A. Shabri, et al., J. Power Soruces 467 (2020) 228345. A. Donazzi, G. Cordaro, A. Barricci, Z. B. Ding, M. Maestri, Electrochim. Acta 335 (2020) 135620. M. Afzal, R. Raza, S. Du, R. Lima, B. Zhu, Electrochim. Acta. 178 (2015) 385 391. D. Yang, G. Chen, L. Zhang, Z. Chen, R. Zhang, M.I. Asghar, et al., J. Power Sources 503 (2021) 230070.

Green Chemistry Approaches to Environmental Sustainability

C H A P T E R

14 Green approaches for the valorization of olive mill wastewater Pawan Kumar Rose1, Mohd. Kashif Kidwai1 and Pinky Kantiwal2 1

Department of Energy and Environmental Sciences, Chaudhary Devi Lal University, Sirsa, Haryana, India 2Department of Vocational Studies and Skill Development, Central University of Haryana, Mahendergarh, Haryana, India

14.1 Introduction The environmental concern caused by fossil fuel usage has been the primary topic of debate in most worldwide gatherings and events, with most governments sending out alarming warnings about depleting oil supplies in the face of a rising population. The devastating study and alert from the UN Intergovernmental Panel on Climate Change require a more structured approach for other sustainable renewable energy [1]. Globally, enormous quantities of investment and resources are spent each year to clean billions of litres of wastewater, and utilizing significant amounts of energy. Worldwide annual olive mill wastewater (OMWW) production ranges between 7 and 30 million m3, counting around 22 million (persons per year) of organic load [2]. OMWW contains significant organic loads, i.e., biochemical oxygen demand (BOD) of 89 100 g/L and chemical oxygen demand (COD) of 80 200 g/L, which pose significant environmental problems. As a result, there is a need to expand the use of cost-effective bioremediation technologies that reduce the organic load and generate capital in terms of value-added products [3,4]. Several biological techniques such as aerobic; composting and vermicomposting and anaerobic; anaerobic digestion (AD) have been attempted and evaluated to decrease the organic load in OMWW and biotransformation into valuable products [5]. OMWW is rich in carbon sources, organic compounds and minerals, making it a valuable resource from a biotechnological perspective that might be valorised as a substrate in several different bioprocesses [6,7]. The initial stage of residue valorization include collection of data on the type, quantity and characteristics of the residue. Next, traditional and prospective

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microbial techniques for the processing these waste streams and production of high-value components must be examined. Alternative areas of valorization have been researched all over the globe utilizing OMWW as raw material. OMWW was utilized to make bioplastics such as polyhydroxyalkanoates. OMWW exhibits low to moderate nitrogen, sugar, volatile acid, polyalcohol and fat levels, making it a viable raw material for bioenergy and biofuel production [8]. Finally, in recent years, several researchers have used OMWW to generate biofuels such as bioethanol, biodiesel, biohydrogen biomethane and manure. The primary objective of this chapter is to provide information on green approaches for the sustainable treatment and biovalorization of OMWW and foresee potential future improvements.

14.2 OMWW: production and characteristics The majority of the world’s olive oil (Olea Europaea L.) is produced in Mediterranean countries, which account for 98% of global production. Each olive tree can produce anywhere from 15 to 40 kg of olives per year, from which the olive oil is extracted. Approximately 23,640,307 tonnes of olives were produced in 2020, most of them were in the Mediterranean area. Countries like Spain, Italy and Tunisia produce the most olives, along with Morocco, Turkey, Algeria and Egypt. Olives are grown throughout the Middle East, the United States, Argentina and Australia, in addition to the Mediterranean Basin (Figs 14.1 and 14.2) [9]. Olive oil production consists of various mechanical or physical approaches, such as washing,

FIGURE 14.1

Olive cultivation across the world in 2020 (FAO, 2022).

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FIGURE 14.2 Production of olive (A) by region and (B) by nation (top 10) in 2020 (FAO, 2022).

decanting, centrifugation and filtering, which maintain the oil originality. Olive oil extraction procedures range from conventional batch pressing to more contemporary continuous centrifugation (three-phase and two-phase). The three-phase method was adopted in the 1970s to increase extraction yields, but it generate considerable amount of wastewater that require Green Chemistry Approaches to Environmental Sustainability

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treatment. During this process, the olive oil is wash with hot water. This procedure has three distinct phases: oil, solid residue in olive cake (olive pulp and stones) and OMWW. The decanter is used to separate the solid residue from two other phases. After that, the liquid phase is centrifuged vertically to separate the olive oil from the OMWW. The significant quantity of water is required in three-phase method (1.25% 1.75% higher than press extraction method) results in a substantial volume of wastewater [10]. In the 1990s, two-phase centrifugation technology was introduced to reduce water use and the resulting effluent. Twophase technology disintegrates the olive paste in olive oil and two-phase olive-mill waste (TPOMW). TPOMW is a mixture of olive husk and OMWW [5]. In contrast, the continuous three-phase technique generates a solid waste known as olive husk or olive pomace and two liquid phases, i.e., oil and OMWW. Further, inconveniences associated with the three-phase technique include high installation costs, energy demand and considerably high OMWW production (80 120 L/100 kg olives). Though the TPOMW (10 L/100 kg olives) produced by the two-phase technique is lower, but has distinctive physicochemical characteristics due to the concentrated contaminants, making its management more challenging (Fig. 14.3) [8]. Several factors, including the variety of olives, fruit ripeness and water used, and the method of extraction (press or centrifuge), significantly affect the OMWW final composition. The primary challenge in olive oil production is the disposal and management of OMWW in an environmentally sustainable and economically feasible manner. OMWW consists of organic substances such as organic acids, lipids, alcohols and polyphenols, which can be transform into potentially harmful phytotoxic chemicals for plants [11]. The discharge of untreated OMWW has serious environmental consequences. The negative effect of OMWW discharge into soil includes seed germination suppression, decreased plant development, decreased microbial metabolism and increased soil hydrophobicity [12]. However, OMWW itself a resource that can be utilized to boost soil fertility and production, due to the presence of organic matter and several minerals, notably potassium. Therefore can be a viable approach to completing the residue-resource cycle. According to the outcomes of the many studies performed on the different kinds of OMWW, 130 lipolytic microbes (56 fungi, 22 yeasts and 52 bacteria), cellulolytic bacteria and pectinolytic fungi have been identified [11]. Among the biological treatments for OMWW; AD, composting and treatments with fungus, bacteria and algae have been recommended as viable approaches for the biovalorization of OMWW. However, numerous challenges still remain, including the growth suppression of methanogenic archaea by phenolic chemicals, acidic pH, low nitrogen content, etc. Additionally, pretreatment is necessary to eliminate toxic components in certain circumstances, such as the wastewater from an olive mill [13,14].

14.3 Green approaches for OMWW treatment 14.3.1 AD In AD, the microorganisms decompose and stabilize organic materials under anaerobic environments, and produce biogas [a mixture of methane (CH4) and carbon dioxide (CO2)] and microbial biomass. The AD is accomplished via four diverse groups of

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FIGURE 14.3 Schematic flowchart of industrial olive oil extraction and composition of wastewater.

microorganisms; fermentative, syntrophic, acetogenic and methanogenic bacteria. In AD, the acid-forming and methane-forming microbes vary in physiology, dietary requirements, growth kinetics and sensitivity to environmental variables. The performance and efficiency of AD is the balance between these two groups of microorganisms [15]. Due to its high organic load, the most commonly employed and attractive biological treatment for OMWW is AD. The primary end products of AD are biogas and digestate. Biogas utility includes fuel for cooking and heating, transportation and generating electricity. Digestate is a nutrient-rich solid or liquid material used as fertilizers, soil amendments, livestock

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bedding, etc. However, efficient AD of OMWW has been hindered by (1) very high BOD and COD value; (2) low pH; (3) the presence of lipid, antimicrobial phenolic compound and formation of long-chain volatile fatty acids during storage which is not only difficult to degrade but also exhibit an inhibitory effect on methanogens; and (4) deficient in nitrogen causes high carbon/nitrogen (C/N) ratio (i.e., above 120, whereas the optimum range for AD is 25 30) [16 18]. According to some studies, a consortium of microbes, acclimatization, individual concentration and combinations of inhibitory substances are also more complicated parameters [19]. These problems can be rectified using different strategies (solo or combinations of two or more in adequate sequence) such as dilution, pretreatment, composition adjustment, pH correction, nutrient addition, co-digestion, inhibitor sequestration, integration of different digestors, etc. [20,21]. The AD is unstable with raw OMWW due to inhibitory ingredients (polyphenols and potassium), poor alkalinity and the absence of ammonia [22]. Therefore 70% 100% dilution has been commonly employed for AD of OMWW. Approximately 80% and 85% organic removal efficiencies with diluted OMWW at 35oC were reported in preliminary laboratory and pilot-scale experimental studies [18]. However, dilution is found unsuitable for a large amount of wastewater which raises the cost of the treatment. A highly organic load (above 10 g/L) and phenolic content (above 2 g/L) have been demonstrated to inhibit the AD process of OMWW [23]. There are various materials and methods employed as pretreatment to remove the phenolic compounds to reduce the toxicity of microorganisms, such as activated carbon, sand filtration, coagulation-flocculation compounds, electro-Fenton method, enzymatic removal, microbial degradation by fungi and algae, etc. [20,24]. Fenton oxidation as chemical pretreatment, removes organic materials from the wastewater without any potential for recovery, and imbalanced the usage of hydrogen peroxide (H2O2) can lead to negative effects due to the generation of more radical and iron sludge [25,26]. Although these processes can reduce phenolic compound, but create other complications, such as more difficult operation conditions with extra cost and the generation of more toxic phenolic derivatives [27]. The most common alkalinity correction method uses NaHCO3, NaOH or Ca(OH)2 [22]. However, chemical additions are not environmentally friendly and cost-effective. Magbanua et al. [28] proposed that the swine manure can improve nitrogen availability and buffer capacity for AD of OMWW. In the anaerobic co-digestion process, two types of waste are mixed and digested in a single reactor to compensate for the deficiency of a certain compound in one waste by its copiousness in another waste, which ultimately enhances biodegradation and CH4 production. Aboelfetoh et al. [19] investigated the codigestion of olive mill waste with dairy manure and observed that the 2:1 ratio and thermophilic AD significantly lowered the digestion period and improved the CH4 production. The study also recommends the thermophilic digestion (55oC) over ambient (16oC 27oC) and mesophilic (35oC) AD. However, poorly treated swine wastewater and manure are highly contaminated with pathogens and antibiotics, which can negatively affect digestion process [29]. Hachicha et al. [30] co-composted OMWW sludge and sesame bark and observed a 52.72% and 72% reduction in total organic matter and hydrophilic phenol degradation, respectively. However, the composting process took 210 days to completely eradicate the polyphenolic compounds, which exhibit long duration and loss of energy recovery aspects associated with AD. The co-digestion of raw OMWW and

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sewage sludge in contact bioreactors seems to be a suitable solution. However, the portion of wastewater in the mixture is the limiting factor due to inhibitory ingredients. The codigestion of raw OMWW and residual solids in a batch reactor exhibited 85.4% 93.4% COD removal efficiencies along with the production of 57.1 6 1.5 Lmethane/LOMWW [31]. Treating diluted OMWW in up-flow anaerobic sludge blanket (UASB) reactors is most advisable over the fixed-bed filters [18]. UASB reactors, in comparison with traditional digesters, are high-rate systems (high organic load rate) that perform anaerobic reactions with reduced hydraulic retention times (HRT) with low energy input [32]. Granular sludge in a UASB reactor maintains extremely active biomass with remarkable settling abilities, resulting in an extremely low sludge volume index that promotes efficient sludge-effluent separation [33,34]. Several factors must be considered to maximize the effectiveness of the UASB reactor to treat wastewater from olive oil production (Fig. 14.4). OMWW containing a high concentration of lipids which needs special attention during UASB treatment due to numerous problems such as clogging, sludge floatation, foams formation, odour emission and biomass washout. Moreover, phenolic compound negatively impacts the granular sludge structure and performance efficiency of UASB. However, carbohydrates (0.42 L CH4/g) and proteins (0.63 L CH4/g) have lower CH4 potential than wastewatercontaining lipids (0.99 L CH4/g), such as OMWW [35]. Azbar et al. [18] recommended a UASB reactor for OMWW treatment having 10 20 g/L of COD value. However, pretreatment is necessary for OMWW before anaerobic treatment. The nitrogen and phosphorus content of OMWW is often low and to ensure the right C:N ratio, chemical supplementation or co-AD with a nutrient-rich feedstock is commonly recommended to enhance process conditions when the AD of OMWW is undertaken [21].

FIGURE 14.4 Factor influencing the UASB reactor efficiency for OMWW. Substrate characteristics

Up-flow velocity

Temperature

Parameters that influence UASB performance Organic Loading Rate (OLR)

pH

Hydraulic Retention Time (HRT)

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14.3.2 Composting Composting is a regulated approach that employs a natural bioxidative activity on organic components to produce a stabilized and sanitized organic substance known as compost via the action of aerobes microorganisms found in the environment and the biomass matrices. The composting process comprises two stages: active composting time (thermophilic stage) and curing (mesophilic stage). The initial phase of composting is mesophilic, where carbon-rich biomass is degraded by mesophilic fungi and bacteria. Fungi first decompose the complex organic matrix into simple components, which are later breakdown by bacteria. Due to this change, the pH drops, and temperature rises, ushering in the thermophilic phase of the composting process. In this phase, thermophiles replace mesophiles, and temperature rise between 40oC and 80oC. As the thermophilic phase progresses, degradation activities become more oriented towards readily fermentable organic components and biomass temperature reach up to 65 C, which facilitate its hygienization. Depending on the biomass matrix, the thermophilic phase may take 21 28 days to mature the compost in piles that are turned or not turned and with and without manually aeration or 14 16 days to mature in bioreactors that use a more complicated system. The humic-like compounds are synthesized during the curing (maturation) phase. In the maturation phase, the temperature drops below 25oC, thermophile activity ceases, mesophiles reappear, oxygen intake decreases and fungi degrade residual organic matter. Over the course of the process (more than 45 days), the composting requires less oxygen and heat sink [11,36]. The composting process is most effective when the optimal parameters for its operation, including the compost temperature, oxygen content, moisture content, aeration rate, turning rate, C/N ratio and particle size, are carefully managed. Olive mill wastes, especially OMWW and olive husk, are shown to be composting suitability. Because of their high stickiness, lignocellulosic materials can be added to provide the ideal physical conditions for OMWW composting. At the end of the thermophilic stage, OMWW can be added to the solid substrate to compensate for water lost during evaporation. This process extended the composting time; however, the solid substrate is enriched with organic matter which is necessary for microbial development. OMWW sludge has higher humification rates, stability and maturity than sludge from evaporation ponds, although either may be employed. However OMWW is low in nitrogen content and slightly acid, which requires carriers with high nitrogen content to compensate and reduce nitrogen losses during composting process. Cotton waste, maize straw, sugarcane bagasse, wheat straw, barley straw, grape marc, rice hulls and solid olive and olive tree waste are only a few of the plant-based waste carriers that have been investigated [37]. There has also been researched on the potential benefits of using nitrogen-rich municipal wastes and animal manure from cattle and poultry farming [37,38]. Although less ecologically desirable, fertilizers amendment such as urea has also been reported [38]. Composting with manure has been suggested by Cayuela et al. [39] as an effective way to revalorize its waste in the region around the olive mills. The OMWW-based compost has a high degree of humification, no phytotoxic impact and a significant concentration of minerals. Composting has been proposed as an economical approach for recycling olive oil wastes with comprehensive detoxification of starting ingredients [40].

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Vlyssides et al. [41] used OMWW as a continuous feed wastewater source and solid residue from olive extraction as bulking material. The composting system was fed with 263 m3 of wastewater over 23 days in the thermophilic phase, for an average rate of 11.4 m3/day (2.9 kg wastewater per kg solid residue). The product was further stabilized in the mesophilic phase for 3 months until it reached room temperature. Zorpas and Inglezakis [42] applied a combination approach using chemical oxidation (using Fenton method), reed beds and composting to treat the highly contaminated wastewater from the olive mill. The COD elimination efficiency using Fenton method was 65% which was further reduced to 28% using reed bed. The last step was composting. OOSR (olive oil solid residue) and treated OMWW create a co-composted material with ideal qualities, agricultural applicability and according to European standards. Composting produces fertilizer via the biodegradation of wastes, frequently mixed with a solid substrate. Composting appears to reduce COD by about 38.2% and phenolic content as much as 83.51%, making the resultant compost suitable for use as fertilizer [43]. The composting of OMWW yields a high-quality compost with a high nutritional content, mostly organically bound nitrogen (1.553%), a high degree of humification (78%) and no phytotoxicity [44]. Hachicha et al. [30] investigated the co-compositing of OMWW sludge with sesame bark. After 7 months of processing, total organic matter was reduced by 52.72%, whereas water-soluble phenol degradation was reduced by 72%. The finished product has been an excellent soil fertilizer. Aviani et al. [45] performed two composting cycles having five different combinations of olive mill solid wastes (OMSW) and moistened with either freshwater or OMWW. Composts made with as much as 0.3 m3 of OMWW per m3 of starting materials exhibited no deterioration in their original chemical, physical or horticultural qualities. Barley straw soaked in OMWW results in compost with acceptable analytical characteristics. At the end of the stabilization and maturation phases, the total organic matter was reduced by 25% and 52%, and phenol degradation reached up to 54% and 95%, respectively. The toxicity of OMWW was disappeared after 2 months of composting [46]. Galliou et al. [47] applied an innovative, easy and inexpensive sun drying and composting approach for OMWW treatment. First, OMWW was dried on swine manure (bulking agent) using a solar greenhouse chamber. For a drying period of 6 months, the average evaporation rate was 5.2 kgwater/m2/day with high phenol loss (75%). In contrast, nitrogen (15%) and carbon (15%) loss were low. Even after sun drying, a large amount of phenols (18.4 g/kg) remained in the compost, along with other nutrients such as nitrogen (27.8 g/kg), phosphorous (7.3 g/kg) and potassium (81.6 g/kg). Composting was performed with grape marc to detoxify the final product, and 1:1 ratio (solar drying product: grape marc) exhibited a higher compost temperature profile (60 C). The compost had the features of organic fertilizer (57% organic carbon) with a better nutritional profile (nitrogen: 3.5%, phosphorous: 1.1%) and low phenol content (2.9 g/kg). It was found to be comparable to commercial NPK fertilizers. OMWW composting necessitates the proper control of pH, temperature, moisture, oxygenation and nutrients for microbial communities to thrive optimally. High pH level ( . 9) is usual during TPOMW composting due to the presence of by-products generated via decarboxylation of organic anions. Therefore, reduces its application in soil, however can be rectified by adding elemental sulphur in the composting process. Lengthy thermophilic period is another problem associated with TPOMW composting, which may be shortened with suitable bulking agents. Odour and the need to treat drainage water are the biggest

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challenges to the widespread use of composting with olive by-products. The use of biofilters to handle the gas generated by compost heaps contributes to the rising expense of this technology [38]. Compositing is a viable technique for the small mill as they can recycle their effluents into environmentally friendly, high-quality organic amenders and fertilizers. Natural evaporation in storage ponds followed by direct dispersion or composting of leftover solid phase is one of the most widely recognized large-scale OMWW management strategies. However, this approach requires a large area and has related issues such as strong odour and insect growth [48]. Microorganisms partially breakdown the organic fraction of OMWW to CO2 and water during composting, while the other portion undergoes humification, resulting in a stable compost with appropriate properties for use as a biofertilizer. However, the composting process should be designed according to product quality and environmental sustainability. If an acceptable product is to be developed from the composting of OMWW and system efficiency is to be maximized, proper system assessment is essential.

14.3.3 Vermicomposting Similar to composting, vermicomposting stabilizes organic matter through a biooxidative process. However, unlike composting, which requires a thermophilic phase (temperature exceeding 35 C is lethal to earthworms), vermicomposting relies on the coupled activities of earthworms and microbial communities. Microbes in the system are accountable for the biochemical decomposition of organic matter, while earthworms are involved in substrate conditioning and the modification of biological activity. Simply earthworms are responsible for aeration, fragmentation and turning. Vermicomposting proceeds best with a moisture level of 70% 90% compared to composting, i.e., 40% 60%). Because vermicomposting does not include a thermophilic phase, it cannot be relied upon to eliminate all human pathogens from the finished product. Vermicompost, which has a higher nutritional content, more active microorganisms and a more appealing visual aspect, has a larger market share than compost. However, vermicomposting has certain drawbacks, including the need for wide spaces for industrial-scale production when using traditional methods like ground beds to disperse the raw material and to avoid high temperature that would kill the earthworms [49,50]. Microorganisms break down the organic matter within and outside the earthworm’s digestive tract. Since most organic matter transformation occurs in the earthworm digestive tract, the finished product (vermicompost) has a low-temperature profile. Earthworm increases the transition of organic phosphorus into mineral forms and reduces the fixation of released phosphorus into insoluble inorganic forms, hence increase the phosphorus availability. The extent of the transformation of phosphorous into a more accessible form (organic to inorganic state) in earthworm (Eisenia fetida)-inoculated organic wastes (kitchen waste, cow dung, poultry droppings, municipal waste and dry leaves) was significantly high [51]. Literature demonstrated that earthworm capacity to survive in industrial waste is considerably low; therefore it is necessary to combine industrial wastes with a nutrient-rich organic source, such as cow dung, biogas plant slurry or poultry droppings, to improve the efficiency of vermicomposting process [49,52]. Several studies have identified that cow dung is most suitable organic

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additive to enhance the vermicomposting process [53,54]. The nitrogen, potassium, calcium and sulphur levels in earthworm-modified waste material has been found similar to those in commercial organic manure. The use of earthworms in dry olive cake biomass was supported by Nogales et al. [55]. Generally, olive oil processing waste is deficient in nitrogen. Adding cattle manure and sewage sludge to the dried olive cake significantly improved earthworm growth and reproduction rate [52]. Several studies revealed the potential of olive oil industry solid waste as a suitable substrate with organic amendments such as sheep manure [56], municipal biosolids [57], cattle manure [58], etc., for the vermicomposting. Moreno et al. [59] investigated the viability of vermicomposting using various by-products from the olive oil industry (wet, semi-dry, and dry cakes, cake pulp and concentrated mill effluent). Only the dry olive cakes, alone or in combination with cow manure, and the precomposted semi-dry olive cakes were found appropriate for vermicomposting. Vermicomposting over 56 days lowered C:N ratios, enhanced chemical characteristics and significantly reduced phytotoxicity of materials. Vermicomposting is an effective method for bioconverting wet olive cake, however requires precomposting which significantly decreased the amount of hazardous chemicals (such as polyphenols) and demonstrated greater initial stability than fresh wet olive cake [60]. However, utilization of the liquid portion of olive oil industry waste is limited due to high phenolic and lignin concentrations. Ganesh et al. [61] observed that OMWW is rich in phenols fraction and lignin concentration and found it inappropriate for the proper growth of most earthworm species. However, the difference in body mass increase among the earthworms species may be related to the influence of earthworm acclimatization. Moreover, the daily growth rate, measured in milligrammes of biomass, was deemed an excellent metric for evaluating earthworm growth among substrates [62]. Kharbouch et al. [63] acclimated the Eisenia andrei for 6 months by introducing modest OMWW concentrations to a mixture of olive pomace, horse manure and wheat straw. The study demonstrated that the E. andrei flourished and multiplied when grown in olive pomace (600 g) supplemented with horse manure (300 g), wheat straw (100 g) and diluted OMWW (0%, 10%, 25%, 50%) in a sock. E. andrei, when acclimated, shown faster reproductive rate and a better rate of OMWW detoxification than non-acclimated earthworms. The 72% decrease in phenols achieved with acclimatized earthworms exemplifies the usefulness of this process at 10% OMWW. After 7 days of incubation, earthworm mortality has been occurred when the OMW ratio approached 50%. The decrease in phenol content was greater in the mixture with 0% OMWW (91%) than in the other combinations (72% in 10% OMWW and 54% in 25% OMWW) [64]. Acclimatization of earthworms can improve their potential adaption to high concentrations of OMWW, despite OMWW being a refractory organic by-product for decomposition. Macci et al. [65] used a lignocellulosic solid matrix saturated with OMWW. A 13-week-long laboratory experiment using 30 mature earthworms of the E. fetida species shown that the almost 90% of the earthworms had reached sexual maturity after 2 weeks. The decrease in total organic carbon (approximately 35%), C:N ratio (from 31.2 to 12.3) and biochemical parameters (hydrolytic enzymes averagely 40% and dehydrogenase 23%), as well as the increase in humification rate indicated the mineralization and stabilization of organic matter. Masciandaro et al. [66] evaluated the viability of utilizing a precomposting technique using straw chip as bulking materials, earthworms (Eisenia fetida) and oat seedlings (Avena

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TABLE 14.1 The advantages and limitations of standard biological methods used to treat OMWW. Methods

Advantages

Limitations

Anaerobic biodegradation

Biogas production, organic matter removal

Start-up inoculum, antimicrobial chemicals, predilution/filtration, source additions, large OMWW quantities, prevent freezing temperatures, wastewater disposal, distinctive equipment, high costs

Composting

High-quality organic fertilizer, nitrogen-rich product, phytotoxic and antibacterial compound degradation, practical

Long maturation duration, required bulking agent such as agricultural waste, high pH compost limit agricultural use

Vermicomposting Vermicompost has high popularity than composts, high nutrient quality, high microbial activities, high nitrogen and phosphorus content

No guarantee of human pathogen elimination, large-scale for commercial production, long duration process (depending on raw material), no thermophilic treatment, initial volatile compound attributed odour, Vermicomposting demands more attention than traditional composting, vermicomposting does not kill weed seeds, vermicompost piles may attract fruit flies, centipedes, millipedes and flies

sativa L.) to increase the value and decrease the phytotoxicity of OMWW. After 3 months, the precomposted material exhibited chemical-physical and biological characteristics comparable to a partly digested compost. Chemical (total organic carbon, water-extractable organic carbon, total nitrogen) and biological (dehydrogenase enzyme activity) parameters were significantly reduced with earthworm treatment. Humic compounds and accessible nitrogen forms were significantly increased. Additionally, the drop in phenolic compounds decreased the phytotoxicity by roughly 50% than the precomposted material, therefore improved the germination index (Table 14.1).

14.4 Biovalorization of OMWW into biofuel 14.4.1 Bioethanol OMWW is also a promising feedstock for bioethanol production because of its abundant organic materials. Some approaches have also been recommended to take advantage of OMW carbohydrate content. However, the phenolic compound must be removed or reduced before utilizing its carbohydrate components. Since OMWW is sugar deficient, blends of external glucose must be evaluated for the process’s economic efficiency. Instead of expensive commercial glucose, wastewater rich in concentrated sugar diluted with OMWW can provide a more economically feasible solution [67]. The Saccharomyces cerevisiae MAK-1 has shown ability to grow in medium with high quantities of phenolic compounds [68]. Under nonsterile conditions, S. cerevisiae can also generate bioethanol, and

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detoxified OMWW. OMWWs presence increased the biomass production in glucose-based flask sterile cultures compared to control cultures. In a batch bioreactor, nonsterilized experiment using OMWW-glucose enriched medium as substrate, the highest bioethanol quantity produced was 52 g/L (conversion yield per sugar ingested of 0.46 g/g). Along with this, OMW was successfully decoloured (63%) and phenol was removed (34%) [68]. Dourou et al. [6] reported that Candida tropicalis LFMB 16 and Saccharomyces cerevisiae MAK-1 generates 21.9 and 31.3 g/L of bioethanol, respectively, when cultured in nonaseptic bioreactor conditions on an OMWW medium supplemented with glucose (65 g/L) for 46 and 16 hours, respectively. Candida tropicalis and S. cerevisiae strains demonstrated remarkable phenol elimination, i.e. 16.5% and 12.9%, respectively. Finally, when flask and bioreactor cultures were compared, bioreactor cultures produced more bioethanol, most likely owing to the low concentration of dissolved oxygen in the bioreactor. In another study, Sarris et al. [69] cultured S. cerevisiae MAK-1 on a molasses-based medium supplemented with OMWW and observed a non-significant reduction in bioethanol and biomass production when compared to control (without OMWW) in non-sterile shake-flask studies under aerated conditions. Under these conditions, significant bioethanol production (34.3 g/L), decolourization (up to 60%) and phenolic component elimination (up to 28%) were observed. When non-sterile aerated bioreactor trials were compared with the nonaerated bioreactor, bioethanol and biomass production was increased to some extent in the latter scenario. Moreover, OMWW as co-substrates for bioethanol synthesis by S. cerevisiae may reduce the expensive of dilution of molasses in large-scale systems. Jamai and Ettayebi [70] reported direct bioethanol production from raw OMW in 90 hours utilizing a fed-batch method of fermentation by C. tropicalis YMEC24 with no previous chemical, physical or enzymatic treatment. Since both strains were grown at acidic pH (C. tropicalis at 4.5 and S. cerevisiae at 3.5), the culture may be free from bacterial contamination and are therefore suitable for large-scale applications. Pretreatment of olive pulp with wet oxidation and enzymatic hydrolysis increased the glucose and xylose bioavailability for fermentation. Enzymatic pretreatment, however, was more efficient [71]. Massadeh and Modallal [72] investigated bioethanol production from OMWW after thermal preconditioning and biological treatment with the fungal strain of Pleurotus sajor-caju. The study reported 68% elimination of the phenolic chemicals in OMWW. Subsequently, 48 hours of fermentation of 50% diluted OMWW with S. cerevisiae L-6 yielded 14.2 g/L of bioethanol.

14.4.2 Biodiesel Through thermochemical processes, olive oil waste can be converted into biofuel such as biodiesel. Olive oil waste-derived biodiesel has negligible sulphur content, therefore significantly reduce the environmental impact [73]. Furthermore, the fatty acids composition of olive mill waste is similar to that of rapeseed oil since both oils contain a high amount of mono-unsaturated fatty acids, mainly oleic acid (C18:1, more than 60%). In addition, the amount of unsaturation fatty acids in olive mill waste oil (84.5%) is comparable to soy (91.5%) and rapeseed oils (83.8%) [74]. Therefore the olive mill waste oil-based biodiesel may comply with international biodiesel standards. Willson et al. [73] reported 5.57% and 1.16% average oil yields (wet basis, Soxhlet extraction method) from the olive mill pomace and wastewater, respectively, which indicate a significant potential of olive mill pomace

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for biodiesel production due to less than 50% of moisture content. El Haijjaji et al. [75] investigated the potential of OMWW and olive pomace as feedstock in triglycerides transesterification into fatty acid methyl esters. The extraction yield was 9.0% and 8.3% for OMWW and olive pomace, respectively. The highest biodiesel yield, i.e. 71% was obtain with olive oil. Two different catalysts, potassium hydroxide and sodium methoxide, were used to convert olive oil waste into biodiesel with 47% and 71% yield. Single-cell oils from oleaginous microorganisms have received increased interest in recent years as a sustainable feedstock for biodiesel synthesis due to the fatty acid chain length and saturation degree being similar to that of vegetable oils [76] as well as the high value of lipid accumulation, i.e., above 20% [77]. Yeasts have several advantages among the tested oleaginous microorganisms due to their higher lipid content, shorter life cycle, easier manipulation, and independence from the season and climate factors [78]. Yousuf et al. [79] reported that a yeast strain (Lipomyces starkeyi) can utilize OMWW and transform it into lipids for biodiesel synthesis. The examined yeast proliferated in the undiluted OMWW and no addition of external organic compounds was required. L. starkeyi significantly reduces the total organic carbon and phenols contents. The lipid output increased to 28.6% with 50% dilution of OMWW compared to 22.4% with undiluted OMWW. The fatty acid profiles demonstrated a high quantity of oleic acid, which exhibits the yeast capability to retain lipids and is appropriate for second-generation biodiesel synthesis. The enzyme produced by Zygomycetes fungi can digest many complex substrates such as starch, cellulose, phytic acid and proteins, which are vital in the industrial sector. These enzymes are capable of catalysing different processes involved in biodiesel production and corticosteroid drug manufacturing [80]. Bellou et al. [81] first time used Zygomycetes strains to convert OMWW into high-value lipids, including polyunsaturated fatty acids. Further OMWW did not affect the development of Mortierella isabellina and Mortierella ramanniana, Cunninghamella echinulata, Mucor sp., Thamnidium elegans and Zygorhynchus moelleri on solidified media up to 50% concentration (v/v). The aquatic Thamnidium elegans and the terrestrial Zygorhynchus moelleri thrived on solid media containing 50% (v/v) OMWW and developed cell masses containing over 60% (w/w) lipids content in surface and submerged culture in liquid condition. Further, the fatty acids profile indicated the presence of oleic and palmitic. Zygorhynchus moelleri contained up to 17.7% (w/w) gamma-linolenic acid in submerged culture with OMWW as the only carbon source. Yarrowia lipolytica thrived in OMWW (supplemented with commercial glucose) with a high phenolic compound concentration and produced lipid-enriched biomass and citric acid. Therefore OMWW addition promotes lipids storage and acts as a "lipogenic" substrate. Yarrowia lipolytica strains can accumulate 15% 25% (w/w) of fat when grown with OMWW [82].

14.4.3 Biohydrogen The most pressing challenges associated with olive mills is the high organic content in raw OMWW and its dark colour. However, olive pulp contains a lot of phenolic compounds, but only 2% are present in olive oil, while the rest are found in OMWW (about 53%) and pomace (45%) [2]. OMWW is an excellent feedstock for biohydrogen production; however, preprocessing is necessary to eliminate inhibitory substances such as polyphenols [83]. Direct and indirect photolysis, photofermentation and dark fermentation are

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commonly used methods for biohydrogen production. The term “dark fermentation” refers to acidogenic fermentation. It is a shortened form of AD in which the AD does not continue to methanogenesis phase, yielding biohydrogen as the final product [3]. Generally, bacteria are used for biohydrogen production through single or multiple catabolic routes, each has its own specific physiological and metabolic characteristics. The organic acids in wastewater are used as a substrate in the photofermentation process, which produces biohydrogen and CO2 gas. The theoretical capability of biohydrogen generation from organic acids by photofermentation has been found effective. Since OMWW has low nitrogen content, it exhibits suitability for biohydrogen production through photofermentative procedure [84]. This approach represents the association between biohydrogen production and wastewaste treatment, overcoming the economic constraints imposed by the expensive culture medium of biohydrogen production [5]. However, the dark colour of OMWW is the major hurdle in biohydrogen production using photosynthetic bacteria. High dilution rates of OMWW have been recommended to address this issue [8]. The OMWW with the high organic load and C/N molar ratio produces more biohydrogen via photofermentation. Alternatively, if OMWW has a low C/N ratio or is diluted, its organic carbon and C/N ratio must be enhanced by utilizing domestic or agroindustrial wastewaters for effective biohydrogen production. Several researchers attempted to assess the use of untreated and diluted OMWW as a substrate for biohydrogen generation. At 2% OMWW, the maximum biohydrogen production potential was 13.9 Lhydrogen/LOMWW by Rhodobacter sphaeroides O.U.001. During biohydrogen production, the COD and the BOD of the diluted wastewater were also reduced by 65.45% and 42.10%. Furthermore, important by-products were also produced, including carotenoid (40 mg/LOMWW) and polyhydroxybutyrate (60 mg/LOMWW) [85]. Almost pure biohydrogen was generated, which allowing it to be used with current energy generation systems. Later, research on linked biological systems found that a clay treatment before photofermentation using R. sphaeroides can significantly increased the productivity of photobiological biohydrogen production. This process produced 35 Lhydrogen/LOMWW and a COD conversion efficiency of 52% [86]. Padovani et al. [87] used four adsorbent matrices: Azolla, granular active carbon, resin and zeolite, for removing polyphenols (first step) from stored OMW followed by a photofermentative procedure (second step) using Rhodopseudomonas palustri sp. to produce biohydrogen. The pretreatment with granular activated carbon and a photofermenter holding 25% of the effluent shown a maximum biohydrogen generation rate of 14.31 mL/L/h. Pretreated OMWW at 50% dilution with synthetic TAP media (tris-acetate-phosphate) was employed as a substrate for Chlamydomonas reinhardtii biohydrogen production [88]. According to the results, TAP-OMW culture generated 37% more biohydrogen (150 mLhydrogen/Lculture) than TAP medium alone (100 mLhydrogen/Lculture). Pintucci et al. [89] employed two culture broths for biohydrogen generation by Rhodopseudomonas palustris 6 A; (1) a sugar (glucose and fructose) enriched synthetic medium and (2) a pretreated (dry-Azolla and granular active carbon) and diluted (30% v/v) fresh OMWW. The specific biohydrogen photoevolution rate in the broth containing diluted OMWW was 13.5 mL/g(dw)/h and 11.8 mL/g(dw)/ h in the synthetic medium. Although the practical utilization of biohydrogen production by photosynthetic microorganisms is still some way off, but has significant potential as a promising renewable energy source [90].

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14.4.4 Biomethane Biohydrogen has a greater heating value than methane and bioethanol, making its application more promising but still impractical. CH4 is an excellent renewable energy source since it produces less CO2 per unit of energy and other pollutants. As a result, its usage in power production, industrial applications and the transportation sector are expected to grow [90]. AD is a well-established waste treatment process, with the end products of digestate (nutrient-rich residual mixtures) and biogas, which is mainly constituted of CH4 (55% 75%) and CO2 (25% 45%), with H2S (0% 1.5%) and NH3 (0% 0.05%). The organic composition, particularly the oil component, is responsible for speculative energy potential of OMWW. If processing issues are overcome, biogas generation from OMWW may be cost-effective. One of them is phenolic toxicity toward microorganisms [5]. Pretreatment is a prevalent practice to reduce phenolic toxicity. Azbar et al. [91] attempted to enhance anaerobic biological degradation for the biogas generation by pretreating OMWW with acid, followed by a coagulation-flocculation process using Al2SO4, FeSO4 and FeCl3. The study proposed that the pretreatment (acid 1 Al2SO4) can significantly improved biogas production (80%) compared to untreated OMWW. The co-digestion of OMWW with other organic waste can be an economically viable alternative for biogas generation instead of the environmentally hazardous chemical pretreatment procedure. Codigestion is an efficient waste treatment system that combines and digests diverse organic substrates in a single anaerobic reactor. This practice provides several significant benefits, such as plant profitability, CH4 yield and consistent operation throughout the year [13]. AD of 20% OMWW and 80% of liquid cow dung under mesophilic conditions was performed utilizing a two-stage process with an HRT of 19 days and found CH4 generation up to 0.91 L/LOMWW/day at a steady-state rate [92]. Maamri and Amrani [93] reported high CH4 (71%) generation at a mixing share of 87.5:12.5 of waste-activated sludge: OMWW at a thermophilic temperature (55 C) for 32 days. Further, fungi have proven to be ideal pretreatment option for OMWW prior to AD. Hamdi [94] pretreated OMWW with Aspergillus niger and observed that CH4 generated in the subsequent AD was twice as high. Borja et al. [95] pretreated OMWW with the fungus Aspergillus terreus and observed CH4 volumetric output of 1.1 Lmethane/LOMWW/day for pretreated OMWW and 0.6 L for untreated OMWW. The aerobically prefermented effluent shown dramatical decrease in phenolic compound content and biotoxicity while increase in the CH4 generation up to 83%. AD can be performed in two phases rather than just one. Intermediate chemicals such as volatile fatty acids (VFA) and alcohol are produced in the first stage by acidogenic bacteria from various complex organic substrates, including carbohydrate, protein, lipid and amino acid chains. Methanogens or archaea then biotransform these compounds into CH4 and CO2 in the second step. Fezzani and Cheikh [96] used two semicontinuous digesters at a mesophilic temperature to explore the two-phase AD potential for OMWW and olive cake mixture combination. The initial stage (acidifier) was carried out over 14 and 24 days, with organic loading rates ranging from 5.54 to 14 g COD/L/day. The final stage (methanizer) was operated at HRTs of 18, 24 and 36 days, with organic loading rates ranging from 2.28 to 9.17 g COD/L/day. VFA concentrations increased with HRT or feed concentrations, and CH4 production was double that of a one-phase reactor [97]. The biogas

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can be used to generate electricity, and residue liquid and solid portion (digestate) can be used in soil because of the abundance of various nutrients such as phosphorus, trace elements and nitrogen. Gonza´lez-Gonza´lez and Cuadros [98] revealed that a 5 days pretreatment provided the optimal conditions for a COD removal of 65% and a CH4 output of 390 Lmethane/kgCOD, representing roughly 72% of total COD to CH4 conversion. Hence, 5 days of the aerobic stage preceding AD resulted in a 143% increase in CH4 generation. The OMWW has been found to produce up to 419 Lmethane/kgVS during monodigestion operations [99], whereas 740 Lmethane/kgVS was produced during the co-digestion of OMSW, OMWW and milk whey [100].

14.5 Concluding remarks and future prospects There is no exaggeration to say that olive oil is a vital agricultural commodity; however, inadequacy in OMWW management causes serious environmental deterioration. So far, no single treatment method has been shown to be compelling enough for an olive oil processing plant. OMWW are currently managed in one of two ways: detained in storage lagoons or disposed into receiving bodies. Neither of these options is preferable, and a chronic and progressive approach is essential for the optimum treatment of OMWW. Therefore any preferred technique must be thoroughly evaluated for its technical viability and possible economic and environmental effects. Technique can involves a biological stage that may incorporate various biotreatments such as AD, composting, vermicomposting, etc. However, these techniques requires innovative engineering to adequately manage OMWW. Among these, the best treatment option can be AD which has ability to reduce pollutants and organic load while simultaneously producing biogas or biomethane for clean energy generation. However, there are still considerable obstacles associated with OMWW treatment, including the low biodegradability of waste, the acidic nature of OMWW, and the presence of inhibitory and recalcitrant substances such as polyphenols. Further, AD of OMWW is currently limited to the research and development stage since most olive processing plants across the world are very modest in size and distributed unevenly across the regions. The energy recovery during treatment and generation of high-value green products during AD, make this process a viable, sustainable alternative to OMWW. An optimal inoculum, pretreatment and co-digestion can improve AD performance. The co-digestion of OMWW with organic wastes indicate an economically effective alternative to the ecologically harmful chemical pretreatment technique for biogas (biomethane) production. Fungi based pretreatment solutions are also efficient for OMWW prior to AD. Biological pretreatment exhibits superiority over physiochemical methods. However, the primary drawback of biological pretreatment is the extended residence periods which increase energy demands. When recycling industrial waste, earthworms are quite helpful since they convert these wastes into valuable goods, such as vermicompost. Several agricultural benefits may be gained by producing high-quality vermicompost by introducing many appropriate earthworms into an industrial waste based substrate and maintaining the optimal conditions

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for their growth. However, not much effective in reducing human pathogen and the requirement of a large area are the major obstacles in the vermicomposting field. Further OMWW has a significant phenolic and lignin contents, making it unsuitable for the growth of most earthworm species, limiting its usefulness in vermicomposting. However, earthworms can adapt to high OMWW concentrations through acclimatization (thermophilic precomposting of OMWW before vermicomposting). OMWW is deficit in nitrogen, but can be made usable by mixing with nitrogen-rich organic materials such as animal manure which also act as a bulking agent. Moreover, OMWW can easily stick to lignocellulosic materials (agricultural residue), providing the ideal physical conditions for composting and vermicomposting. OMWW provides organic matter and makes up water lost via evaporation during composting. OMWW-based compost has a high nutrient content, high humification and negligible phytotoxicity. The use of composting has been suggested as a cost-effective solution for OMWW. However, issues such as high pH ( . 9), long thermophilic phase, odour and the requirement to treat drainage water are the most significant barriers in OMWW-based composting. Olive oil waste is also a suitable feedstock for bioethanol and biodiesel production because of its carbohydrate concentration and high quantity of mono-unsaturated fatty acids, mainly oleic acid (C18:1, over 60%), respectively. However, the phenolic compound must be eliminated or decreased before its utilization. Further, OMWW lacks sugar but can be mix with concentrated sugar-containing wastewater for bioethanol production. Olive oil waste-derived biodiesel has low sulphur content. Because of its improved fuel characteristics, olive mill waste may be an appropriate feedstock for biodiesel production. Due to its low nitrogen concentration, photofermentative biohydrogen generation is a viable option for OMWW management. This concept establishes a link between biohydrogen generation and waste management, eliminating the economic limits imposed by costly growth medium. However, like other biofuels, preprocessing is necessary to remove inhibiting compounds like polyphenols. Since biohydrogen production requires photosynthetic bacteria, the dark colour of OMWW is a significant hindrance, but increase in dilution rate have been recommended to address this issue. Unfortunately, dilution is not a viable option for treating vast amounts of wastewater since it drives up treatment costs. Overall AD, composting and vermicomposting can be technically and economically feasible treatment options for OMWW. Additional revenue from high-value green products such as biofuels and manure might aid in the spread of OMWW bioremediation and biovalorisation. Further improvement in government policy is required to boost the production and commercial application of biofuels and other value-added products. The triangle between producer (farmers), innovator (research institution) and beneficiary (industries) is mutually dependent on their interaction. It requires support from government regulations for the successful commercialization of olive oil waste-based green products. Further, these products can be harvested throughout the bioconversion process, making olive oil waste a complete utility for bioconversion to biofuels and other valueadded products. The commercial usability of these green products can increase the economic feasibility of olive oil waste management by delivering extra money from waste resources and promoting the circular economy.

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References [1] O. Olatunji, S. Akinlabi, N. Madushele, Application of lignocellulosic biomass (LCB), Valorization of Biomass to Value-Added Commodities, Springer, Cham, 2020, pp. 3 19. Available from: https://doi.org/10.1007/ 978-3-030-38032-8_1. [2] J.J. Mateo, S. Maicas, Valorisation of winery and oil mill wastes by microbial technologies, Food Res. Int. 73 (2015) 13 25. Available from: https://doi.org/10.1016/j.foodres.2015.03.007. [3] A. ElMekawy, G. Mohanakrishna, S. Srikanth, D. Pant. The role of bioreactors in industrial wastewater treatment. In Ram Chandra, Environ. Waste Manag. 2015, pp. 157 183 [4] P.K. Rose, Bioconversion of agricultural residue into biofuel and high-value biochemicals: recent advancement, in: Y.K. Nandabalan, V.K. Garg, N.K. Labhsetwar, A. Singh (Eds.), Zero Waste Biorefinery. Energy, Environment, and Sustainability, Springer, Singapore, 2022, pp. 233 268. Available from: https://doi.org/ 10.1007/978-981-16-8682-5_9. [5] A. ElMekawy, L. Diels, L. Bertin, H. De Wever, D. Pant, Potential biovalorization techniques for olive mill biorefinery wastewater, Biofuels, Bioprod. Bioref. 8 (2) (2014) 283 293. Available from: https://doi.org/ 10.1002/bbb.1450. [6] M. Dourou, A. Kancelista, P. Juszczyk, D. Sarris, S. Bellou, I.E. Triantaphyllidou, et al., Bioconversion of olive mill wastewater into high-added value products, J. Clean. Prod. 139 (2016) 957 969. Available from: https://doi.org/10.1016/j.jclepro.2016.08.133. [7] R. Lanciotti, A. Gianotti, D. Baldi, R. Angrisani, G. Suzzi, D. Mastrocola, et al., Use of Yarrowia lipolytica strains for the treatment of olive mill wastewater, Bioresour. Technol. 96 (3) (2005) 317 322. Available from: https://doi.org/10.1016/j.biortech.2004.04.009. [8] P.M. Ahmed, P.M. Ferna´ndez, L.I. Castellanos, H.F. Pajot, Exploitation alternatives of olive mill wastewater: production of value-added compounds useful for industry and agriculture, Biofuel Res. J. 22 (2019) 980 994. Available from: https://doi.org/10.18331/BRJ2019.6.2.4. [9] FAOSTAT, 2022. Food and Agriculture Organization Corporate Statistical Database. Food and Agriculture Organization of the United Nations (FAO). World Production/Crops. http://www.fao.org/faostat/en/? #data/QC , last accessed 2022/08/09. [10] S. Souilem, A. El-Abbassi, H. Kiai, A. Hafidi, S. Sayadi, C.M. Galanakis, Olive oil production sector: environmental effects and sustainability challenges, Olive Mill Waste, Academic Press, 2017, pp. 1 28. Available from: https://doi.org/10.1016/B978-0-12-805314-0.00001-7. [11] P. Toscano, F. Montemurro, ’Olive mill by-products management’, in: I. Muzzalupo (Ed.), Olive Germplasm - The Olive Cultivation, Table Olive and Olive Oil Industry in Italy, IntechOpen, London, 2012. [12] A. Piotrowska, M.A. Rao, R. Scotti, L. Gianfreda, Changes in soil chemical and biochemical properties following amendment with crude and dephenolized olive mill waste water (OMW, Geoderma 161 (1 2) (2011) 8 17. Available from: https://doi.org/10.1016/j.geoderma.2010.11.011. [13] S. Dermeche, M. Nadour, C. Larroche, F. Moulti-Mati, P. Michaud, Olive mill wastes: biochemical characterizations and valorization strategies, Process. Biochem. 48 (10) (2013) 1532 1552. Available from: https://doi. org/10.1016/j.procbio.2013.07.010. [14] S. Plazzotta, L. Manzocco, Food waste valorization, Saving Food, Academic Press, 2019, pp. 279 313. Available from: https://doi.org/10.1016/B978-0-12-815357-4.00010-9. [15] Y. Chen, J.J. Cheng, K.S. Creamer, Inhibition of anaerobic digestion process: a review, Bioresour. Technol. 99 (10) (2008) 4044 4064. Available from: https://doi.org/10.1016/j.biortech.2007.01.057. [16] G. Di Giacomo, P. Romano, Evolution of the olive oil industry along the entire production chain and related waste management, Energies 15 (2) (2022) 465. Available from: https://doi.org/10.3390/en15020465. [17] C. Meziti, A. Boukerroui, Regeneration of a solid waste from an edible oil refinery, Ceram. Int. 37 (6) (2011) 1953 1957. Available from: https://doi.org/10.1016/j.ceramint.2011.02.016. [18] N. Azbar, A. Bayram, A. Filibeli, A. Muezzinoglu, F. Sengul, A. Ozer, A review of waste management options in olive oil production, Crit. Rev. Environ. Sci. Technol. 34 (3) (2004) 209 247. Available from: https://doi.org/10.1080/10643380490279932. [19] M. Aboelfetoh, A. Hassanein, M. Ragab, M. El-kassas, E.R. Marzouk, Olive mill waste-based anaerobic digestion as a source of local renewable energy and nutrients, Sustainability 14 (3) (2022) 1402. Available from: https://doi.org/10.3390/su14031402.

Green Chemistry Approaches to Environmental Sustainability

332

14. Green approaches for the valorization of olive mill wastewater

[20] A. Hassan, J. Jeries, Co-digestion of olive mill wastewater and swine manure using up-flow anaerobic sludge blanket reactor for biogas production, J. Water Resour. Prot. 2 (2010) 314 321. Available from: https://doi. org/10.4236/jwarp.2010.24036. [21] A. Messineo, M.P. Maniscalco, R. Volpe, Biomethane recovery from olive mill residues through anaerobic digestion: a review of the state of the art technology, Sci. Total Environ. 703 (2020) 135508. Available from: https://doi.org/10.1016/j.scitotenv.2019.135508. [22] Y. El Gnaoui, F. Sounni, M. Bakraoui, F. Karouach, M. Benlemlih, M. Barz, et al., Anaerobic co-digestion assessment of olive mill wastewater and food waste: effect of mixture ratio on methane production and process stability, J. Environ. Chem. Eng. 8 (4) (2020) 103874. Available from: https://doi.org/10.1016/j.jece. 2020.103874. [23] K. Tsigkou, M. Sakarika, M. Kornaros, Inoculum origin and waste solid content influence the biochemical methane potential of olive mill wastewater under mesophilic and thermophilic conditions, Biochemical Eng. J. 151 (2019) 107301. Available from: https://doi.org/10.1016/j.bej.2019.107301. [24] S. Shabir, N. Ilyas, M.S. Ahmad, M.M. Al-Ansari, L. Al-Humaid, M.S. Reddy, Designing of pretreatment filter technique for reduction of phenolic constituents from olive-mill wastewater and testing its impact on wheat germination, Chemosphere 299 (2022) 134438. Available from: https://doi.org/10.1016/j.chemosphere. 2022.134438. [25] K. Bampalioutas, A. Vlysidis, G. Lyberatos, A. Vlyssides, Detoxification and methane production kinetics from three-phase olive mill wastewater using Fenton’s reagent followed by anaerobic digestion, J. Chem. Technol. Biotechnol. 94 (1) (2019) 265 275. Available from: https://doi.org/10.1002/jctb.5772. [26] A. Serrano, F.G. Fermoso, B. Alonso-Farin˜as, G. Rodrı´guez-Gutie´rrez, S. Lo´pez, J. Fernandez-Bolan˜os, et al., Performance evaluation of mesophilic semi-continuous anaerobic digestion of high-temperature thermally pre-treated olive mill solid waste, Waste Manag. 87 (2019) 250 257. Available from: https://doi.org/ 10.1016/j.wasman.2019.02.003. [27] A. Tsioulpas, D. Dimou, D. Iconomou, G. Aggelis, Phenolic removal in olive oil mill wastewater by strains of Pleurotus spp. in respect to their phenol oxidase (laccase) activity, Bioresour. Technol. 84 (3) (2002) 251 257. Available from: https://doi.org/10.1016/S0960-8524(02)00043-3. [28] B.S. Magbanua Jr, T.T. Adams, P. Johnston, Anaerobic codigestion of hog and poultry waste, Bioresour. Technol. 76 (2) (2001) 165 168. Available from: https://doi.org/10.1016/S0960-8524(00)00087-0. [29] N.T. Malintan, M.A. Mohd, Determination of sulfonamides in selected Malaysian swine wastewater by highperformance liquid chromatography, J. Chromatogr. A 1127 (1 2) (2006) 154 160. Available from: https:// doi.org/10.1016/j.chroma.2006.06.005. [30] S. Hachicha, J. Cegarra, F. Sellami, R. Hachicha, N. Drira, K. Medhioub, et al., Elimination of polyphenols toxicity from olive mill wastewater sludge by its co-composting with sesame bark, J. Hazard. Mater. 161 (2 3) (2009) 1131 1139. Available from: https://doi.org/10.1016/j.jhazmat.2008.04.066. [31] T.H. Ergu¨der, E. Gu¨ven, G.N. Demirer, Anaerobic treatment of olive mill wastes in batch reactors, Process. Biochem. 36 (3) (2000) 243 248. Available from: https://doi.org/10.1016/S0032-9592(00)00205-3. [32] F. Tufaner, Evaluation of COD and color removals of effluents from UASB reactor treating olive oil mill wastewater by Fenton process, Sep. Sci. Technol. 55 (18) (2020) 3455 3466. Available from: https://doi.org/ 10.1080/01496395.2019.1682611. [33] S. Chong, T.K. Sen, A. Kayaalp, H.M. Ang, The performance enhancements of upflow anaerobic sludge blanket (UASB) reactors for domestic sludge treatment a state-of-the-art review, Water Res. 46 (11) (2012) 3434 3470. Available from: https://doi.org/10.1016/j.watres.2012.03.066. [34] M. Mainardis, M. Buttazzoni, D. Goi, Up-flow anaerobic sludge blanket (UASB) technology for energy recovery: a review on state-of-the-art and recent technological advances, Bioengineering 7 (2) (2020) 43. Available from: https://doi.org/10.3390/bioengineering7020043. [35] K. Nakasaki, K.K. Nguyen, F.C. Ballesteros Jr, T. Maekawa, M. Koyama, Characterizing the microbial community involved in anaerobic digestion of lipid-rich wastewater to produce methane gas, Anaerobe 61 (2020) 102082. Available from: https://doi.org/10.1016/j.anaerobe.2019.102082. [36] K. Palaniveloo, M.A. Amran, N.A. Norhashim, N. Mohamad-Fauzi, F. Peng-Hui, L. Hui-Wen, et al., Food waste composting and microbial community structure profiling, Processes 8 (6) (2020) 723. Available from: https://doi.org/10.3390/pr8060723.

Green Chemistry Approaches to Environmental Sustainability

References

333

[37] E. Tsagaraki, H.N. Lazarides, K.B. Petrotos, Olive mill wastewater treatment, in: V. Oreopoulou, W. Russ (Eds.), Utilization of By-Products and Treatment of Waste in the Food Industry, 3, Springer, Boston, MA, 2007, pp. 133 157. Available from: https://doi.org/10.1007/978-0-387-35766-9_8. [38] J.A. Morillo, B. Antizar-Ladislao, M. Monteoliva-Sa´nchez, A. Ramos-Cormenzana, N.J. Russell, Bioremediation and biovalorisation of olive-mill wastes, Appl. Microbiology Biotechnol. 82 (1) (2009) 25 39. Available from: https://doi.org/10.1007/s00253-008-1801-y. [39] M.L. Cayuela, M.P. Bernal, A. Roig, Composting olive mill waste and sheep manure for orchard use, Compost. Sci. Utilization 12 (2) (2004) 130 136. Available from: https://doi.org/10.1080/1065657X. 2004.10702171. [40] L. Baeta-Hall, M.C. Sa`a´gua, M.L. Bartolomeu, A.M. Anselmo, M.F. Rosa, Bio-degradation of olive oil husks in composting aerated piles, Bioresour. Technol. 96 (1) (2005) 69 78. Available from: https://doi.org/ 10.1016/j.biortech.2003.06.007. [41] A.G. Vlyssides, D.L. Bouranis, M. Loizidou, G. Karvouni, Study of a demonstration plant for the cocomposting of olive-oil-processing wastewater and solid residue, Bioresour. Technol. 56 (2 3) (1996) 187 193. Available from: https://doi.org/10.1016/0960-8524(96)00010-7. [42] A.A. Zorpas, V.J. Inglezakis, Intergraded applied methodology for the treatment of heavy polluted waste waters from olive oil industries, Appl. Environ. Soil. Sci. (2011) 1 14. Available from: https://doi.org/ 10.1155/2011/537814. [43] Paraskeva, C.A., Zagklis, D.P., Arvaniti, E.C., Papadakis, V.G., October. Olive mill wastewater treatment methods: sustainability and benchmarking. In Prosodol Symposium on ‘Olive Mill Wastes and Environmental Protection, 2012, pp. 16 18). [44] U. Tomati, E. Galli, F. Fiorelli, L. Pasetti, Fertilizers from composting of olive-mill wastewaters, Int. Biodeterior. Biodegrad. 38 (3 4) (1996) 155 162. Available from: https://doi.org/10.1016/S0964-8305(96) 00044-3. [45] I. Aviani, Y. Laor, S. Medina, A. Krassnovsky, M. Raviv, Co-composting of solid and liquid olive mill wastes: management aspects and the horticultural value of the resulting composts, Bioresour. Technol. 101 (17) (2010) 6699 6706. Available from: https://doi.org/10.1016/j.biortech.2010.03.096. [46] B. Zenjari, H. El Hajjouji, G.A. Baddi, J.R. Bailly, J.C. Revel, A. Nejmeddine, et al., Eliminating toxic compounds by composting olive mill wastewater straw mixtures, J. Hazard. Mater. 138 (3) (2006) 433 437. Available from: https://doi.org/10.1016/j.jhazmat.2006.05.071. [47] F. Galliou, N. Markakis, M.S. Fountoulakis, N. Nikolaidis, T. Manios, Production of organic fertiliser from olive mill wastewater by combining solar greenhouse drying and composting, Waste Manag. 75 (2018) 305 311. Available from: https://doi.org/10.1016/j.wasman.2018.01.020. [48] G. Alfano, G. Lustrato, G. Lima, G. Ranalli, Present and future perspectives of olive residues composting in the Mediterranean Basin (CompMed), Dynamic Soil, Dynamic Plant, Global Science Books, Isleworth, UK, 2009, pp. 39 56. [49] Y. Zhou, R. Xiao, T. Klammsteiner, X. Kong, B. Yan, F.C. Mihai, et al., Recent trends and advances in composting and vermicomposting technologies: a review, Bioresour. Technol. (2022) 127591. Available from: https://doi.org/10.1016/j.biortech.2022.127591. [50] C. Tognetti, F. Laos, M.J. Mazzarino, M.T. Hernandez, Composting vs. vermicomposting: a comparison of end product quality, Compost. Sci. Utilization 13 (1) (2005) 6 13. Available from: https://doi.org/10.1080/ 1065657X.2005.10702212. [51] M. Ghosh, G.N. Chattopadhyay, K. Baral, Transformation of phosphorus during vermicomposting, Bioresour. Technol. 69 (2) (1999) 149 154. Available from: https://doi.org/10.1016/S0960-8524(99)80001-7. [52] A. Yadav, V.K. Garg, Industrial wastes and sludges management by vermicomposting, Rev. Environ. Sci. Bio/Technology 10 (3) (2011) 243 276. Available from: https://doi.org/10.1007/s11157-011-9242-y. [53] U. Ali, N. Sajid, A. Khalid, L. Riaz, M.M. Rabbani, J.H. Syed, et al., A review on vermicomposting of organic wastes, Environ. Prog. Sustain. Energy 34 (4) (2015) 1050 1062. Available from: https://doi.org/10.1002/ ep.12100. [54] M. Mago, R. Gupta, A. Yadav, V.K. Garg, Sustainable treatment and nutrient recovery from leafy waste through vermicomposting, Bioresour. Technol. 347 (2022) 126390. Available from: https://doi.org/10.1016/j. biortech.2021.126390.

Green Chemistry Approaches to Environmental Sustainability

334

14. Green approaches for the valorization of olive mill wastewater

[55] R. Nogales, R. Thompson, A. Calmet, E. Benitez, M. Go´mez, C. Elvira, Feasibility of vermicomposting residues from olive oil production obtained using two stage centrifugation, J. Environ. Sci. Health Part. A 33 (7) (1998) 1491 1506. Available from: https://doi.org/10.1080/10934529809376800. [56] A. Vivas, B. Moreno, S. Garcia-Rodriguez, E. Benitez, Assessing the impact of composting and vermicomposting on bacterial community size and structure, and microbial functional diversity of an olive-mill waste, Bioresour. Technol. 100 (3) (2009) 1319 1326. Available from: https://doi.org/10.1016/j.biortech.2008.08.014. [57] E. Benitez, H. Sainz, R. Nogales, Hydrolytic enzyme activities of extracted humic substances during the vermicomposting of a lignocellulosic olive waste, Bioresour. Technol. 96 (7) (2005) 785 790. Available from: https://doi.org/10.1016/j.biortech.2004.08.010. [58] C. Plaza, R. Nogales, N. Senesi, E. Benitez, A. Polo, Organic matter humification by vermicomposting of cattle manure alone and mixed with two-phase olive pomace, Bioresour. Technol. 99 (11) (2008) 5085 5089. Available from: https://doi.org/10.1016/j.biortech.2007.09.079. [59] R. Moreno, E. Benitez, R. Melgar, A. Polo, M. Gomez, R. Nogales, Vermicomposting as an alternative for reusing by-products from the olive oil industry, Fresenius Environ. Bull. 9 (1/2) (2000) 001 008. [60] R. Melgar, E. Benitez, R. Nogales, Bioconversion of wastes from olive oil industries by vermicomposting process using the epigeic earthworm Eisenia andrei, J. Environ. Sci. Health, Part. B 44 (5) (2009) 488 495. Available from: https://doi.org/10.1080/03601230902935444. [61] P.S. Ganesh, S. Gajalakshmi, S.A. Abbasi, Vermicomposting of the leaf litter of acacia (Acacia auriculiformis): possible roles of reactor geometry, polyphenols, and lignin, Bioresour. Technol. 100 (5) (2009) 1819 1827. Available from: https://doi.org/10.1016/j.biortech.2008.09.051. [62] C.A. Edwards, N.Q. Arancon, The use of earthworms in the breakdown of organic wastes to produce vermicomposts and animal feed protein, Earthworm Ecol. 2 (2004) 345 380. [63] B. Kharbouch, H. Lakhtar, S. Amat, S. Roussos, N. Dupuy, A.E. Mousadik, Effect of Acclimatization on Earthworm’s (Eisenia Andrei) Potential on Olive Mill Wastewaters Detoxification, in: A. Kallel, M. Ksibi, H. Ben Dhia, N. Khe´lifi (Eds.), Recent Advances in Environmental Science from the Euro-Mediterranean and Surrounding Regions. EMCEI 2017. Advances in Science, Technology & Innovation, Springer, Cham, 2018, pp. 955 957. Available from: https://doi.org/10.1007/978-3-319-70548-4_277. [64] Kharbouch, B., Lakhtar, H., Amat, S., Roussos, S., Perissol, C., Criquet, S., et al. August. Nutrient recovery from olive by-products through vermicomposting with Eisenia andrei. In 15th International Conference on Environmental Science and Technology, 2017. [65] C. Macci, G. Masciandaro, B. Ceccanti, Vermicomposting of olive oil mill wastewaters, Waste Manag. Res. 28 (8) (2010) 738 747. Available from: https://doi.org/10.1177/0734242X09345278. [66] G. Masciandaro, C. Macci, S. Doni, B. Ceccanti, Use of earthworms (Eisenia fetida) to reduce phytotoxicity and promote humification of pre-composted olive oil mill wastewater, J. Sci. Food Agric. 90 (11) (2010) 1879 1885. Available from: https://doi.org/10.1002/jsfa.4028. [67] D. Sarris, S. Papanikolaou, Biotechnological production of ethanol: biochemistry, processes and technologies, Eng. Life Sci. 16 (4) (2016) 307 329. Available from: https://doi.org/10.1002/elsc.201400199. [68] D. Sarris, M. Giannakis, A. Philippoussis, M. Komaitis, A.A. Koutinas, S. Papanikolaou, Conversions of olive mill wastewater-based media by Saccharomyces cerevisiae through sterile and non-sterile bioprocesses, J. Chem. Technol. Biotechnol. 88 (5) (2013) 958 969. Available from: https://doi.org/10.1002/jctb.3931. [69] D. Sarris, L. Matsakas, G. Aggelis, A.A. Koutinas, S. Papanikolaou, Aerated vs non-aerated conversions of molasses and olive mill wastewaters blends into bioethanol by Saccharomyces cerevisiae under non-aseptic conditions, Ind. Crop. Products 56 (2014) 83 93. Available from: https://doi.org/10.1016/j. indcrop.2014.02.040. [70] Jamai, L., Ettayebi, M. Production of bioethanol during the bioremediation of olive mill wastewater at high temperatures. In Proceedings of the Third International Renewable and Sustainable Energy Conference (IRSEC), 2015. pp. 1 6. Available from: https://doi.org/10.1109/IRSEC.2015.7455034. [71] P.K. Rose, S.B. Dhull, M.K. Kidwai, Cultivation of wild mushrooms using lignocellulosic biomass-based residue as a substrate, in: S.B. Dhull, A. Bains, P. Chawla, P.K. Sadh (Eds.), Wild Mushrooms: Characteristics, Nutrition, and Processing, CRC Press, 2022, pp. 493 520. Available from: https://doi.org/10.1201/9781003152583. [72] M.I. Massadeh, N. Modallal, Ethanol production from olive mill wastewater (OMW) pretreated with Pleurotus sajor-caju, Energy Fuels 22 (1) (2008) 150 154. Available from: https://doi.org/10.1021/ef7004145.

Green Chemistry Approaches to Environmental Sustainability

References

335

[73] R.M. Willson, Z. Wiesman, A. Brenner, Analyzing alternative bio-waste feedstocks for potential biodiesel production using time domain (TD)-NMR, Waste Manag. 30 (10) (2010) 1881 1888. Available from: https:// doi.org/10.1016/j.wasman.2010.03.008. [74] B.P. Chapagain, Z. Wiesman, MALDI-TOF/MS fingerprinting of triacylglycerols (TAGs) in olive oils produced in the Israeli Negev desert, J. Agric. food Chem. 57 (4) (2009) 1135 1142. Available from: https://doi. org/10.1021/jf8025277. [75] S. El Haijjaji, C. Bouladab, I.A. Belkasmi, S. Hinnach, Valorization of diverse low-value wastes into biodiesel, J. Mater. Environ. Sci. 7 (12) (2016) 4502. [76] S. Bellou, I.E. Triantaphyllidou, P. Mizerakis, G. Aggelis, High lipid accumulation in Yarrowia lipolytica cultivated under double limitation of nitrogen and magnesium, J. Biotechnol. 234 (2016) 116 126. Available from: https://doi.org/10.1016/j.jbiotec.2016.08.001. [77] I.A. Nascimento, S.S.I. Marques, I.T.D. Cabanelas, S.A. Pereira, J.I. Druzian, C.O. de Souza, et al., Screening microalgae strains for biodiesel production: lipid productivity and estimation of fuel quality based on fatty acids profiles as selective criteria, Bioenergy Res. 6 (1) (2013) 1 13. Available from: https://doi.org/10.1007/ s12155-012-9222-2. [78] J.M. Ageitos, J.A. Vallejo, P. Veiga-Crespo, T.G. Villa, Oily yeasts as oleaginous cell factories, Appl. Microbiology Biotechnol. 90 (4) (2011) 1219 1227. Available from: https://doi.org/10.1007/s00253-011-3200-z. [79] A. Yousuf, F. Sannino, V. Addorisio, D. Pirozzi, Microbial conversion of olive oil mill wastewaters into lipids suitable for biodiesel production, J. Agric. food Chem. 58 (15) (2010) 8630 8635. Available from: https://doi. org/10.1021/jf101282t. [80] J.A. Ferreira, P.R. Lennartsson, L. Edebo, M.J. Taherzadeh, Zygomycetes-based biorefinery: present status and future prospects, Bioresour. Technol. 135 (2013) 523 532. Available from: https://doi.org/10.1016/j. biortech.2012.09.064. [81] S. Bellou, A. Makri, D. Sarris, K. Michos, P. Rentoumi, A. Celik, et al., The olive mill wastewater as substrate for single cell oil production by Zygomycetes, J. Biotechnol. 170 (2014) 50 59. Available from: https://doi. org/10.1016/j.jbiotec.2013.11.015. [82] D. Sarris, N.G. Stoforos, A. Mallouchos, I.K. Kookos, A.A. Koutinas, G. Aggelis, et al., Production of addedvalue metabolites by Yarrowia lipolytica growing in olive mill wastewater-based media under aseptic and non-aseptic conditions, Eng. Life Sci. 17 (6) (2017) 695 709. Available from: https://doi.org/10.1002/ elsc.201600225. [83] B. Debnath, S.K. Ghosh, Hydrogen generation from biorefinery waste: Recent advancements and sustainability perspectives, Waste Valorisation and Recycling, Springer, Singapore, 2019, pp. 557 572. Available from: https://doi.org/10.1007/978-981-13-2784-1_53. ˙ Eroglu, ˘ [84] B. Uyar, G. Kars, I. M. Yu¨cel, U. Gu¨ndu¨z, Hydrogen production via photofermentation, in: N. Azbar, D.B. Levin (Eds.), State of the Art and Progress in Production of Biohydrogen, Bentham Science Publishers, United Arab Emirates, 2012, p. 54. ˙ Eroglu, ˘ ˘ [85] E. Eroglu, U. Gu¨ndu¨z, M. Yu¨cel, L. Tu¨rker, I. Photobiological hydrogen production by using olive mill wastewater as a sole substrate source, Int. J. Hydrog. Energy 29 (2) (2004) 163 171. Available from: https://doi.org/10.1016/S0360-3199(03)00110-1. ˙ Eroglu, ˘ ˘ [86] E. Eroglu, I. U. Gu¨ndu¨z, L. Tu¨rker, M. Yu¨cel, Biological hydrogen production from olive mill wastewater with two-stage processes, Int. J. Hydrog. energy 31 (11) (2006) 1527 1535. Available from: https://doi. org/10.1016/j.ijhydene.2006.06.020. [87] G. Padovani, C. Pintucci, P. Carlozzi, Dephenolization of stored olive-mill wastewater, using four different adsorbing matrices to attain a low-cost feedstock for hydrogen photo-production, Bioresour. Technol. 138 (2013) 172 179. Available from: https://doi.org/10.1016/j.biortech.2013.03.155. [88] C. Faraloni, A. Ena, C. Pintucci, G. Torzillo, Enhanced hydrogen production by means of sulfur-deprived Chlamydomonas reinhardtii cultures grown in pretreated olive mill wastewater, Int. J. Hydrog. energy 36 (10) (2011) 5920 5931. Available from: https://doi.org/10.1016/j.ijhydene.2011.02.007. [89] C. Pintucci, G. Padovani, A. Giovannelli, M.L. Traversi, A. Ena, B. Pushparaj, et al., Hydrogen photoevolution by Rhodopseudomonas palustris 6A using pretreated olive mill wastewater and a synthetic medium containing sugars, Energy Convers. Manag. 90 (2015) 499 505. Available from: https://doi.org/ 10.1016/j.enconman.2014.11.045.

Green Chemistry Approaches to Environmental Sustainability

336

14. Green approaches for the valorization of olive mill wastewater

[90] C. Kourmentza, E. Koutra, N. Venetsaneas, M. Kornaros, Integrated biorefinery approach for the valorization of olive mill waste streams towards sustainable biofuels and bio-based products, in: V. Kalia, P. Kumar (Eds.), Microbial Applications, 1, Springer, Cham, 2017, pp. 211 238. Available from: https://doi.org/ 10.1007/978-3-319-52666-9_10. [91] N. Azbar, T. Keskin, E.C. Catalkaya, Improvement in anaerobic degradation of olive mill effluent (OME) by chemical pretreatment using batch systems, Biochem. Eng. J. 38 (3) (2008) 379 383. Available from: https:// doi.org/10.1016/j.bej.2007.08.005. [92] M.A. Dareioti, S.N. Dokianakis, K. Stamatelatou, C. Zafiri, M. Kornaros, Exploitation of olive mill wastewater and liquid cow manure for biogas production, Waste Manag. 30 (10) (2010) 1841 1848. Available from: https://doi.org/10.1016/j.wasman.2010.02.035. [93] S. Maamri, M. Amrani, Evaluation and modelling of methane yield efficiency from co-digestion of waste activated sludge and olive mill wastewater, Appl. Ecol. Env. Res. 17 (2) (2019) 5259 5274. Available from: https://doi.org/10.15666/aeer/1702_52595274. [94] M. Hamdi, Effects of agitation and pretreatment on the batch anaerobic digestion of olive mil, Bioresour. Technol. 36 (2) (1991) 173 178. Available from: https://doi.org/10.1016/0960-8524(91)90176-K. [95] R. Borja, J. Alba, S.E. Garrido, L. Martinez, M.P. Garcia, C. Incerti, et al., Comparative study of anaerobic digestion of olive mill wastewater (OMW) and OMW previously fermented with Aspergillus terreus, Bioprocess. Eng. 13 (6) (1995) 317 322. Available from: https://doi.org/10.1007/BF00369564. [96] B. Fezzani, R.B. Cheikh, Two-phase anaerobic co-digestion of olive mill wastes in semi-continuous digesters at mesophilic temperature, Bioresour. Technol. 101 (6) (2010) 1628 1634. Available from: https://doi.org/ 10.1016/j.biortech.2009.09.067. [97] F. Boubaker, B.C. Ridha, Anaerobic co-digestion of olive mill wastewater with olive mill solid waste in a tubular digester at mesophilic temperature, Bioresour. Technol. 98 (4) (2007) 769 774. Available from: https://doi.org/10.1016/j.biortech.2006.04.020. [98] A. Gonza´lez-Gonza´lez, F. Cuadros, Effect of aerobic pretreatment on anaerobic digestion of olive mill wastewater (OMWW): an ecoefficient treatment, Food Bioprod. Process. 95 (2015) 339 345. Available from: https://doi.org/10.1016/j.fbp.2014.10.005. [99] P.S. Calabro`, A. Fo`lino, V. Tamburino, G. Zappia, D.A. Zema, Increasing the tolerance to polyphenols of the anaerobic digestion of olive wastewater through microbial adaptation, Biosyst. Eng. (2018). Available from: https://doi.org/10.1016/j.biosystemseng.2018.05.010. [100] F. Battista, D. Fino, F. Erriquens, G. Mancini, B. Ruggeri, Scaled-up experimental biogas production from two agro-food waste mixtures having high inhibitory compound concentrations, Renew. Energy. (2015). Available from: https://doi.org/10.1016/j.renene.2015.03.007.

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C H A P T E R

15 Depolymerization of waste plastics and chemicals Archana Kumari1, Sarmistha Debbarma2, Prabhakar Maurya3 and Vivek Anand4 1

Shriram Institute for Industrial research, New Delhi, India 2Animal Resources Development Department, Gurkhabusti, Tripura, India 3Consultancy for Environmental & Human Toxicology and Risk Assessment (Fr), India Office, New Delhi, India 4Department of Chemistry, University Institute of Science, Chandigarh University, Gharuan, Mohali, Punjab, India

15.1 Introduction Plastic consumption is at peak at current times, and every single minute in the world about 1 million plastic bottles are purchased, and every year about 5 trillion plastic bags are used. In total, half of the manufactured plastics are meant for single use [1]. In fact, due to the massive accumulation of plastics and microplastics in the ecosystem, one more component has been added to the ecosphere coined as “plastisphere.” During the era of 1950s to the 1970s, the relative management of plastic wastes was relatively easier. However, from 1990s onwards, an exponential surge has been seen in the generation of plastic waste and it has risen to almost triple the earlier levels, and in early 2000s the amount of plastic waste generated in a single decade was more than what it was in the previous four decades [2]. In the present scenario, we produce an amount of plastic waste equivalent to the entire weight of human population on earth, that is, about 300 million tonnes. In addition, the production of plastic is much more than that of any other manmade material. Notably, it is showing sharp shift towards single use plastic products, which is quite worrisome. During the period of 1950 to 2017, approximately 76% of plastics produced turned into waste which amounts to about 7000 million tonnes out of 9200 million tonnes. According to global production of primary plastic forecast, by 2050 the world will be reaching 34 billion tonnes. As the present scenario is concerned, plastic products have become significant part of human lives. Hence, we are now facing two critical

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issues. Firstly, lowering the volume of waste stream of uncontrolled and mismanaged plastic into environment and secondly, enhancing the recycling levels of plastic leftover. Therefore we need to slow down the flow of plastic at its source itself as well as improvement in the organization of plastic contamination is also required. The different types of commercial plastics and their applications in different walks of life are depicted in Fig. 15.1.

15.2 Plastic and their classifications Plastics are polymers formed by the bonding of long chain of monomers, which can be easily modified and shaped. Broadly plastics can be categorized into three categories based on source of origin: natural, synthetic plastics and semisynthetic.

15.2.1 Natural plastics Natural plastics are naturally occurring materials that can be moulded into different shapes by the application of heat. One of the primitive plastics is amber which is a form of resin from fossilized pine trees. Other examples are animal bones, horns, wax from bees, linen, tortoise shell casein and so on.

FIGURE 15.1

Types of commercially useful plastics and their uses.

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15.2.2 Semisynthetic plastics These are obtained by the modification of the naturally occurring materials. One of the common examples is cellulose acetate, which is used in making films. This polymer is produced by the reaction of cellulose fibre with acetic acid.

15.2.3 Synthetic plastics This category of plastic is produced by the cracking or breaking down of organic materials like coal, crude oil or gas. Mostly, such reactions are carried out in petrochemical refineries under high temperature and pressure. Furthermore, plastics are broadly divided into thermosets and thermoplastic. Thermoplastics are the class of polymers that can be reheated, reshaped and hardened repeatedly. Therefore their properties make them mechanically fit for recycling. Thermosets, on the other hand, are also synthetic plastics which when exposed to different heat treatments pass through a series of physicochemical transformation processes, and thus a three-dimensional network is created within the structural framework. Hence, they are irreversible plastics. In thermoset class of plastics, a change in physical state is possible, that is, from liquids with low viscosity to solids with a high m.p. To maximize and optimize the functionality of plastics, different additives such as binders, pigments, fillers and plasticizers are supplemented with these polymers. The broad division of plastics on the basis of their source of origin and properties is shown in Fig. 15.2. On the basis of size, plastics can be classified as nano (1 μm size range), micro (21 μm 5 mm size range), meso (5 mm 5 cm size range), macro (5 50 cm size range) and mega ( . 50 cm size range) as shown in Fig. 15.3.

FIGURE 15.2 Division of plastics on the basis of their origin and properties.

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FIGURE 15.3

15. Depolymerization of waste plastics and chemicals

Classification of plastics on the basis of their size.

15.3 History of plastics From earlier times, many natural polymers are in use, among them animal bones, sap from tropical trees, wax from bees are few. In 1972, Papier mache was patented as plastic with mouldable properties. In that century, Gutta percha was also extracted from tropical trees, which find wide range of application in household items and in insulation of submarine telegraph cable. In 1838, first semisynthetic material called vulcanite was invented by mixing of heated latex rubber with sulphur. Vulcanite was used to make match stick holders moulded into pipe system and mouth pieces for musical instruments. In France, a polymer/plastic Bois Durci made of cellulose blended with albumen from cow’s blood was patented in 1855. The compression moulded Bois Durci was often used in making inlaid wood plaque. In 1862, immense interest was laid on parkesine plastic material which was invented by Alexander Parkes by mixing cellulose wood flour and cotton waste in nitric acid. In 1869, commercial doping of cellulose nitrate was done by mixing camphor. The commercial name assigned to the material was celluloid. In those days, celluloid was used in making billiard balls and nowadays it is used in manufacturing tennis balls. In fact, celluloid was the first mass produced plastics. In the year 1898, polyethylene (PE) was synthesized by Hans von Pechmann, a German chemist. Since then, it has been one of the most widely used polymer in plastic manufacturing industry, as it is highly resistant to acids as well as alkalis and many organic solvents and displays property of being water proof. In 1907, Bakelite (chemical name phenol formaldehyde) was developed in Belgium. Bakelite was the first pure synthetic plastic, which is heat resistant, durable and finds multiple applications. In those days, it was mostly used in electrical appliances. However, nowadays it has become enormously popular plastic material for domestic products [3]. Interestingly, the early development in polymer technology occurred without much knowledge of the molecular structure of polymers. However, in 1901 by the enormous

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effort of Emil Fisher, the linkage between the chains of amino acids in the formation of protein (natural polymer) was discovered. Moreover, first synthetic fibre Nylon was prepared in 1938 and its structure was correctly predicted by Hermon Staudinger. With the advent of wood in many commercial applications, it replaced metal as a cheaper alternative. Indeed, plastic products have got entrance in almost all the fields we can think off from tooth brush to RxF1 (applied in space ship) [3].

15.4 Harmful effects of plastic waste Pollution refers to harmful by-products rejected to the environment after usage of the material. Plastic wastes, since decades, have toxified the lands with degraded chemicals of organic and inorganic origin, which can penetrate into the soil and can alter its acidity and alkalinity [4]. The degraded microplastics, through primarily and secondary source, easily get entry into the environment not only in soils but their load is also accumulated in air as well in aquatic environment. Poor waste disposal often led to leachable being extracted out from the plastics and reaches the water bodies and get distributed in aquatic as well as terrestrial regions. Plastics are often composed of carbon compounds such as phthalates, polyfluorinated flame retardants and antimony trioxide, all having potential toxicity [5]. Moreover, plastic residues often contain other complex contaminants. Most prominent application of plastic materials is in the packaging (40%) of stock and packaged finished products in different sectors of manufacturing [6]. Because of their sustainable, costeffective and energy-efficient characteristics, plastics have found diversified packaging applicability in industries for the packaging of food, pharmaceutical products, personal care products and so on. Nevertheless, at the end, overburden of post-utilization wastes loads up as processing of plastic wastes is lagging behind significantly as compared to the production pace. On a parallel note, more than 90% of raw plastics is still manufactured using fossil fuels (natural gas or oil). The synthesized macromolecules are converted to plastics by injection, blow moulding or heat forming [1]. Depolymerization to its monomers helps in recovery of hydrocarbon oil and gases and it has enormous potential in easing plastic waste load and solving energy crisis both in a single run [7,8].

15.5 Complexity associated with plastic waste Commercial products obtained from plastics are composed of about 70% polypropylene (PP) fibres and 14% thermosets, adhesives, coatings and sealants [9]. These material properties limit the recyclability and even when recyclability is possible, there is a limitation on the recyclability cycle. Additionally, the incineration of waste plastics leads to the emission of poisonous gases, which is a serious threat in overburdening out air pollutant load. Bioplastics, most touted as ecofriendly, are obtained from renewable biomass sources. Therefore they are to a large extent biodegradable and biocompatible to the environment [10,11]. By 2019, it was estimated that only 55% of the bioplastics were biodegradable. In fact, biodegradability of the bioplastics requires optimum condition to reach the desired fate in the environment [12]. Moreover, blending of bioplastics with other materials to

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meet the commercial requirements often renders them to unknown environmental fate [13]. Therefore the blends need careful postconsumption management and therefore should be safely released into the environment [14 16]. On the onset of latest COVID-19 epidemic, places such as households, quarantine centres and other healthcare centres have acted as a source point for exorbitant generation of plastic wastes [17,18]. Thus the pandemic amplified the burden of waste from basic protective equipment such as face mask, gloves, cleaning products and sanitizers [19]. There are reports revealing how millions of synthetic face mask and gloves have been disposed post COVID on already polluted cities [20 22]. The diverse types of plastic wastes and their distribution in the environment are shown in Fig. 15.4.

15.6 Management strategies to control plastic waste pollution In addition to natural processes, anthropogenic activities of humans are the major contributor of waste generation. Wastes can be biodegradable and thus environment friendly or non-biodegradable which are harmful for the environment as they do not convert to basic elements such as C, H, N and O from which they are actually formed and persist for very long duration of times, sometimes even more than thousands of years. Several scientific waste management strategies have been established, among them recycling, incineration, bioremediation and landfills have drawn significant attention.

FIGURE 15.4

Distribution of plastic waste on the basis of their chemical origin.

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15.6.1 Recycling This process comprises six steps including collection, sorting, arranging into categories, washing away impurities, shredding and resizing [23]. Various methods both mechanical and chemical or recycling methodologies are used to treat plastic wastes, and some of these methods such as closed-loop recycling (primary), mechanical recycling (secondary), chemical recycling and incineration (tertiary) are applied. This method of waste management promotes sustainable lifestyle and reduces waste load of the terrestrial ecosystem [24]. However, the method is not best suited for environment air pollution. Moreover, the method often ends up producing secondary unconsumable plastic wastes because this plastic has now become unfit for another round of recycling [25,26]. 15.6.1.1 Primary recycling It is a closed-loop process and involves subjecting of sorted discarded plastic to grinding, washing, remodeling and extrudtion, to make fresh products with similar quality applications [27]. 15.6.1.2 Secondary recycling It involves mechanical reprocessing of initial plastic leftover materials. Processing takes place by subjecting the polymer to high degree temperatures and mechanical processes, resulting in formation of low-grade plastics having inferior properties in terms of thermal stability or mechanical strength. Secondary recycling is also termed as downcycling because of the deteriorated performance of the reprocessed materials [9]. 15.6.1.3 Tertiary recycling Tertiary recycling involves recycling by using chemical processing techniques like depolymerization, gasification and pyrolysis. Pyrolysis includes the process of chemical supported thermolysis, catalyst-induced cracking and liquefication of the waste plastics, which convert them into gases, liquids and waxes [28 30]. This is a process to recover the crude petroleum and hydrocarbon by-products. Pyrolysis method is classified into three broad categories: high temperature (higher than 800 C), medium temperature (600 C 800 C) and low temperature ( # 600 C) process, depending on the temperature applied to destruct the plastic wastes. The by-products obtained from pyrolysis depend on various factors such as type of reactor, residue, condensation, feeding and the range of temperature. For traditional pyrolysis, it is very important to avoid side reactions and also narrowing product distribution, as there is poor control over reaction pathway. The drawback associated with this method is the investment of huge amount of money during the instalment and running of the processing plants. Nevertheless, it is an efficient waste management technology. Gasification is another chemical recycling method, which process the waste plastic under high temperature in the presence of gasifying agents like air or oxygen. Depolymerization is another method included in tertiary recycling which converts the polymers to monomers or oligomers by disrupting and breaking certain bonds. Chemical recycling is low on cost benefit ration in terms of time required and energy consumed. Further, it is not suitable for all kind of plastics such as polyolefins with robust chemical

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bonds. Reduced performance of reprocessed products is due to presence of plasticizers, inks, dyes and adhesives, making the process of recycling process exhaustive. 15.6.1.4 Incineration Incineration refers to the end-of-life treatment of plastic mixed waste at a sizable scale. It is considered as an all-purpose technology and is employed without the need of separation [31 33]. The various types of recycling technologies prevalent nowadays are shown in Fig. 15.5.

15.6.2 Landfills Landfills are the places where disposal plastic wastes (post utilization) are buried under the earth surface. However, full precautions are taken while burring so that no pollution occurs to the ground water and soil. In this process, first step is the selection of a safer area to protect all dimensions of the ecosystem [34,35]. Different polymer wastes take different time periods to decompose due to differences in their biochemical and structural properties. In addition, different climatic conditions such as sunlight and wind are also responsible for the time required for degradation. Landfills can also serve as a source of energy due to the formation of gases during biodegradation such as methane (CH4) and carbon dioxide (CO2). Although landfills work as a means to keep cities clean, its disadvantages include generation of methane gas as a by-product, which is partially responsible for climate change.

FIGURE 15.5

Recycling technologies available for plastic management.

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15.6.3 Bioremediation It refers to the process of waste decomposition with the aid of microorganisms. In order to facilitate the growth of microorganisms, the culture medium requires optimization of different culture conditions such as nutrients, enzymes, pressure and temperature [36]. Enzymes like oxidoreductase, oxygenase, lactase, peroxidase, hydrolase and lipase of microbial origin act as catalyst by reducing the activation energy and hence mediate the conversion of substrate into the product [37,38]. The previously discussed methods involving degradation using physical or chemical techniques have some undesirable consequences to the environment. Therefore look out for biological methods, that is, biodegradation utilizing microorganisms and its metabolic specificity has increased prominence [39]. Specific bacterial or fungal strains metabolize the plastic through aid of metabolites secreted by them. Secretion of metabolites (poly hydroxyl alkanoate depolymerases) combined with abiotic factors coordinates in the breakdown of plastics into simpler forms such as monomers or dimers or into smaller molecules such as water and gases through combination of multiple processes such as depolymerization and fragmentation. For instance, Ideonella sakaiensis, a bacteria extracted from landfills, has been found to be efficient at degrading polyethylene terephthalate (PET). Some other specific strains with potential to degrade plastic wastes are Aspergillus, Penicillium, Moraxella, Nocardia and Alcanivorax borkumensis. These microbial stains have been proved to be very good candidates for efficient degradation of petroleum-based plastics. Species like Arenibacter latericius and Marinobacter can metabolize PET (also abbreviated PETE) and low-density polyethylene (LDPE). It has been observed that after incubation for 6 months, strains of Pseudomonas results in 28.42% and 37.09% degradation of plastics and polythene wastes, respectively. Research findings showed that when comparison was made in strains of fungi and bacteria, Streptomyces has higher potential for degrading plastics especially polyethylene. Studies showed that hydrocarbonoplastic microorganisms such as Arcobacter and Colwellia are the best candidates for aquatic eco-restoration at pelagic and benthic levels, as they can efficiently degrade the hydrocarbons. It has been reported that out of 100 plastic degrading fungi, Oomycota spp. was characterized as the most efficient. Marasmius oreades and Agaricus bisporus that are saprotrophic strains have been found to be the most efficient at degrading polyurethane (PU) and polyethylene. Biotechnological methods using enzymatic degradation wherein enzymes were produced from biological messengers have been found to be very time efficient methods for plastic degradation. Further research calls for harmonization of innovation advocating improved techniques for breakdown, degradation and remediation of plastics [40 42]

15.6.4 Upcycling by depolymerization By the year 2015 estimates, 79% of plastic waste generated enters landfills or accumulates in the environment and 12% of plastic waste is incinerated and only a minor quantity, that is, 9% is recycled and that too was downcycled to low value products which were low in recyclability. Upcycling is a more environmental friendly and attractive method for recycling of plastic wastes [43 45]. Upcycling is basically the method employed to convert low price plentiful polymer wastes into high-quality products in the

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form of chemical energy, carbon, hydrogen or polymeric structures [46]. Upcycling is going to ease our plastic waste load significantly by way of generation of products having high value. 15.6.4.1 Upcycling to chemical monomers Catalytic decomposition of the polymers to monomers is dependent on the strength of molecular bonds in the plastics. For instance, PET is relatively facile because of the possibility of ester haemolysis. Catalytic depolymerization back to original monomers is not easy because plastics have strong chemical linkages that are not broken by normal techniques of degradation. Moreover, activation of unstrained ethers is required in many polymers. Amongst the polyamides (PAs), only Nylon-6 (manufactured from 7-membered ε-caprolactam ring) is appropriate for depolymerization back to monomers with higher yields and selectivity [47]. Similarly, biotechnology is offering path for depolymerization of the polymers to their monomers. Moreover, nanoscopically dispersed enzymes on polyester have been proved to improve substance accessibility and promote nearly complete depolymerization of the polyester. 15.6.4.2 Catalysis hydrogenolysis Hydrogenolysis is a type of depolymerization in which carbon bonds are disrupted with the assistance of hydrogen. This method is mainly applicable to PET and PE. Compared to other depolymerization processes, hydrogenolysis is more promising and accessible. However, after repeated application, the method losses its efficiency because of the layering of carbon over the surface of catalyst. However, the activity can be restored by calcination in oxygen followed by reduction with hydrogen. PAs resist catalytic hydrogenation because of the strong H-bonds present within the polymer chain. Nevertheless, DMSO solvent assisted catalytic hydrogenation in the presence of ruthenium catalyst depolymerizes Nylon-6 to amino alcohol [48,49]. The role of dimethyl sulfoxide (DMSO) is to rupture the H-bonding and stabilize the uncoordinated state of the metal centre. 15.6.4.3 Upcycling to fuels Upcycling of very common prevailing plastic wastes like high-density polyethene (HDPE) from milk containers, LDPE from plastic bags, polypropylene (PP) from food wraps and polystyrene (PS) from polymer foam to high grade hydrogen gas and high value carbon products has been achieved by microwave-induced catalysis. Carbon and hydrocarbon content in petroleum hydrocarbons is close to that of many plastics like polyolefins [50,51]. Moreover, the caloric values of wastes from plastic are comparable to those of currently used liquid fuels. Therefore the fuel obtained from plastic wastes are considered as a potential substitute fuel production source [52,53]. Conventional methods like gasification and pyrolysis convert plastic waste to fuels. However, the fuels obtained by these methods require tedious processes of upgrading so that they can be used for commercial purposes. In contrast, upcycling produces high-performance fuels directly, therefore, it has tremendous potential in circumventing energy needs by utilizing useless plastic wastes.

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15.6.4.4 Upcycling to hydrogen Photoreforming is a solar supported technology that converts organic compounds and water to H2 [54]. Photoreforming of polymer was initially endeavoured in 1981 using platinized TiO2 in an aqueous solution of sodium hydroxide (5 M). This catalytic process attained hydrogen gas production rate of 64.3 6 14.7, 3.42 6 0.87 and 0.85 6 0.28 nmol H2 gcds21 from polylactic acid (PLA), PET and polyurethane (PUR), respectively. Strong alkali condition plays vital role in partial solubilization and hydrolysis, which significantly improved the photoreforming efficiently. The factors responsible for effective conversion are (1) generation of heat, (2) heat transfer from catalyst to plastic, (3) initiation of scissioning of C-H bond over the catalyst surface by the microwave, (4) Fe3C generated by FeAlOx after partial carbon species reaction assists in formation of multiwalled carbon nanotubes (CNTs). Compared to conventional heating process, specific heating of the catalyst may promote the desorption of H2 from active site avoiding other basic side reactions. 15.6.4.5 Upcycling to alkane Pt nanoparticles-based catalyst selectively cleaves the carbon bonds in PE at regular intervals. The polymer bounds on the surface of nanocatalyst through polymer surface interaction, after which the cleavage occurs. Small molecules (mostly alkanes of different chain lengths) are thus released from the catalyst surface due to the weakening of interaction between the catalyst and small molecules. Nowadays, tandem catalysis is emerging as an effective approach towards the upcycling technology, which does not consume external hydrogen [55]. Gross metathesis using low value short alkanes enables perfect conversion of different types of polyethene to waxes and liquid fuels under relatively milder condition of temperature (B175 C). Moreover, Re2O7/Al2O3 catalyses the breaking of PE chain by decomposing the double bonds. Thus Ir-H2 complex hydrogenates alkene to saturated alkane. Short hydrocarbon is generated after reaction of PE fragments of long chain with high alkane via multiple cross-alkane metathesis process. Due to oxygen content closeness in plastics and liquid fuel, upcycling of plastic has the advantages of consuming very small amount of external H2. Catalytic hydrogenolysis can convert polyethylene and polypropylene into hydrocarbon products including waxes, lubricants, diesel and other lighter hydrocarbon gaseous fuels [56 58]. 15.6.4.6 Upcycling to carbon materials Conversion of plastic wastes to multifarious carbon materials like carbon dots, carbon microsphere, carbon nanofibres, carbon nanosheets, 3D porous carbon, CNTs, graphite and graphene by using carbon sequestration is gaining considerable attention nowadays [59,60]. For instance, conversion of polyolefin plastics including polyethene and polypropylene to CNT has been accomplished by two steps. First, the plastics are converted to gaseous products, which in turn are transformed to CNTs over nickel or Fe supported catalysts [61]. Plastic waste generated carbon materials have potential applications as absorbents, electro-catalysts, super capacitors, batteries and solar vapour generating materials. Sulfonated carbon scaffold is achieved by microwave-assisted sulfonation of LDPE pyrolysis at 900 C. This scaffold can be applied as interlayer material in Li sulphur batteries [62 65].

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15.6.5 Polymerization The monomers obtained from plastic depolymerization can be upcycled to highperformance plastics. For instance, the plastic bisphenol A polycarbonate (BPA-PC) is polycondensed with diarly fluorides to give a upcycled product polyaryl ether sulfone (PSUs), which is an active phenoxide. Plastic valourization with biomass resources is a crucial strategy in the upscaling of plastics. For example, the mixture of partially glycolyzed PET and bio-based monomers upcycled PET by-products into high value composite materials over a titanium butoxide based catalyst [66]. The use of polymer waste as feedstock in animal additives lays out a sustainable pathway for upcycling towards a circular economy. Advanced oxidation process (AOPs) including photocatalytic oxidation has a potential for catalytic oxidation of polymer wastes. These methods were primarily designed for the decomposition of low molecular weight soluble organic wastes such as bisphenol and phthalate plasticizers. In this method, hydrolyzable plastics are first depolymerized to their monomers and then treated in the form of molecule by AOP. Ester bonds are depolymerized by reacting 80% hydrazine hydrate with sodium hydroxide. Then the reaction product is treated by Fenton reagent. AOP and hydrothermal hydrolysis degrade polyethylene-based microplastics into a biodegradable organic intermediate in H2O. Magnetic N-doped nanocarbon catalyst degrades microplastics with excellent efficiency. The degraded product can be used as carbon source for algae cultivation. Electro-Fenton system promotes the degradation of polyvinyl chloride (PVC) microplastics by cooperation of reduction and oxidation reaction using TiO2/graphite as cathode versus Ag/AgCl as reference at 100 C for 6 h with dechlorination efficiency of 75%. Complete mineralization of PE, PP and PVC into CO2 was attained via photocatalytic degradation using single unit cell thick Nb2O5 layered catalyst under stimulated environmental conditions. Conversion of plastic to acetic acid in the presence of Nb2O5 catalyst is achieved through a sequential photoinduced C-C bond cleavage and coupling pathway, and the by-product obtained was employed as promising high-energy density C2 fuels. The degradation of HDPE microsphere in an aqueous solution over hydroxyl rich, ultrathin BiOCl catalyst under stimulated solar light for 5 h resulted in a weight loss of 5.38%. The degradation efficiency of microplastic at solid solid interface is relatively higher than that in liquid phase. This is because reactive species can directly attack polymers in absence of hindrance, offered by direct contact of the solid surfaces. 100% mineralization by formation of CO2 with total moles close to the carbon content in the feedstock under stimulated environment conditions is inspiring as it has not been achieved by other AOP. 15.6.5.1 Polymer depolymerization methods It refers to degradation of oxygen containing plastics to its monomers and then repolymerization to yield high-quality plastic with suitability of recycling. These methods have been employed for various types of plastics such as for the depolymerization of PET, polyolefins, PVC, PS, Nylon and acrylonitrile butadiene styrene (ABS) polymer. 15.6.5.2 Liquid and Gaseous hydrocarbon fuel production With the growing population, energy crisis is a major global concern. Generation of fuel in the form of oils from plastic wastes is an important area with potential to mitigate

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energy crisis. Degradation and repolymerization process of plastics such as PET in presence of oxygen results in the production of high-quality plastics. Two major methods applied in the conversion of polyolefin into fuels are pyrolysis and supercritical water depolymerization. Pyrolysis typically requires much more energy than supercritical water depolymerization and the oil produced by pyrolysis needs upgradation for the improvement of the product quality. Moreover, acid catalysts are often required to carry out the conversion. Acid catalysts possessing meso- and micropores give better conversion. Strong catalysts result in the production of lower hydrocarbon, in the range of C3 C5 hydrocarbon chain. In pyrolysis, the salient features of employing suitable catalysts are (1) requirement of reduced temperature, (2) production of iso-alkanes and aromatics in the range of C5 C10 which are highly demanded gasoline range hydrocarbons [67]. Super critical water depolymerization, a thermochemical process, requires temperature more than 374.15 C along with a pressure of more than 22.129 MPa. On reaching critical point of water, the physicochemical rapidly changes and these alterations are reflected in the molecular diffusivity and viscosity of water [68,69]. These changes enable the method to exhibit fast selection and efficient conversion rate in the transformation of organic wastes to oil. As compared to the thermal cracking method, the yield in the supercritical water depolymerization is high and coke production is small [70 72]. For instance, oils derived from polypropylene have the potential to be used as gasoline blend stocks or feedstocks for other chemicals. Recycling of PS by thermal or thermocatalytic decomposition, on the other hand, generates oil of C6 C12 aromatic hydrocarbon range along with gaseous fraction and solid residue [73].

15.6.6 Bioplastics The problem associated with conventional plastics is slow degradability and thus persistence in the environment creating scope for long-term environmental toxicity [74]. Moreover, even recycling of the plastic is not often feasible and cause negative ecobalance. Thus, the extensive use of plastics and further creation of environmental implication ushered us into a new and exciting era of bioplastics. Bioplastics are either biobased polymers or biodegradable synthetic polymers or both. The synthesis and design of bioplastics is a sub-division of green chemistry. Green chemistry is a branch of chemistry focussed on designing environmental and health friendly products and processes [75]. Basically, the principle behind the sustainability is maintenance of conditions under which human and nature, co-exist harmoniously, where the present needs do not jeopardize the future in terms of health and environmental sustainability [76]. The important biopolymers having widespread commercial applications are bio-based PE, bio-based PET, bio-based PC and bio-based PU. Few important bioplastics are discussed in the following sections. 15.6.6.1 Polylactic acid Polylactic acid is made from the monomer lactic acid which is either microbial origin catalysed fermentation product of sugar or starch derived from corn, sugarcane and tapioca. Engineered Escherichia coli and woven bamboo fabric can also be used to produce polylactic acid or its copolymers.

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15.6.6.2 Polyhydroxyalkanoates Under anaerobic conditions, anaerobic bacteria can produce polyhydroxyalkanoates (PHAs) through polyhydroxy fatty acids utilizing sugar or lipids. Agro and food wastes can also be used for PHA production. 15.6.6.3 Alginate Alginate is a polysaccharide and is obtained from brown algae cell walls and is used for films and coatings of edible products. 15.6.6.4 Polytrimethylene terephthalate Polytrimethylene terephthalate is a type of polyester prepared from 1, 3-propanediol through aerobic fermentation of glucose or glycol. 15.6.6.5 Polyglycolic acid Polyglycolic acid is a biodegradable, thermoplastic polymer constituting simple linear, aliphatic polyester derived from glucose. The classification of different types of biodegradable plastics is shown in Fig. 15.6.

15.6.7 Bio-based additives Performance of plastic is improved by addition of different materials to it to increase its various properties. Such additives may include plasticizers, flame retardants, pigments,

FIGURE 15.6

Different types of biodegradable polymers.

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UV stabilizers and mineral fillers; these are used either as single additive or in combination. Most of these additives are ecotoxic and so renewable alternatives to these additives are being explored [77,78]. Few bio-based additives are natural lubricants, esterified glucose based PVC plasticizers, renewable air release additives, and renewable dimethyl succinate based pigments and UV stabilizers.

15.6.8 Microplastics After degradation by various mechanisms, the plastics get rendered to varied sizes such as nanoplastics, microplastics, mesoplastics, macroplastic and megaplastics. Microplastics are smaller fragments with a size range of 5 100 nm in the form of granules, fibres, fragments and pellets with high persistence in environmental media [79 81]. Due to weathering of plastic debris, they get broken down to minute particles and time duration required for the degradation may vary from 50 to 600 years and even more. Furthermore, only weathering phenomenon is not responsible for the generation of microplastics and their nano forms. Along with this, disposal of consumer products, industrial wastes also possess full potential in the generation of microplastics. Their broad specific surface area invites organic and inorganic pollutant, resulting in indirect toxicity. Moreover, different types of microplastics have great affinity for polycyclic aromatic hydrocarbons (PAH), persistant organic pollutants (POPs), polychlorinated biphenyls, dichloro-diphenyltrichloroethane, nonyl phenol and dioxins. Microplastics may cause deleterious impact on the living organisms and environment after getting loaded with toxicity causing chemicals such as PAH, or heavy metals such as Pb, Cd as well as pathogenic organisms. Microplastics are now uniformly spread across water bodies of earth whether it is freshwater estuaries or seas and oceans, and are even present in soil. Prime risk factors associated with microplastics is their highly stable nature causing long-term presence in the environment. It has been claimed that microplastics combine with hydrophobic contaminants and through the food chain gain entry into animal body. Microplastic pollution is emerging exponentially and is estimated to outnumber the numbers of fishes by 2050. The reason behind this is haphazard usage and poor management of post consumed plastic products and their ingredients, which chiefly originates from textile, fertilizer, pharmaceuticals and cosmetics industries. For the removal of microplastics, its identification is very crucial, although the task at hand is complicated too. For identification of microplastics, various separation techniques as well as sorting by visual or filtration techniques are commonly used. Moreover, spectroscopic techniques such Raman spectroscopy or IR spectroscopy are suitable for microplastics detection ranging between the size of 20 to 100 μm. Apart from this, Fourier transform infra-red spectroscopy is most commonly used for the detection of chemical composition of the microplastics. Other promising alternatives for the elaborate characterization and identification of microplastics are microscopic techniques such as transmission electron, atomic force, scanning electron and stereomicroscopy and X-ray based spectroscopic techniques such as photoelectron and energy disperse methods. Removal of microplastics can be approached by physical, chemical and biological methods. Physical removal can be achieved by adsorption on microalgae, dynamic membrane filtration, membrane bioreactor, tertiary treatment technologies and membrane

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bioreactors combined with conventional activated sludge. Chemical methods include classic coagulation and agglomeration method along with electrocoagulation. Biological approach, on the other hand, for the removal of microplastics includes the digestion and degradation of particles by marine organisms and bacteria [82]. However, among these methods, biological removal approach has the lowest efficiency rate and research is still underway to find more efficient technologies.

15.7 Conclusion In this chapter, the classification of plastics has been briefly discussed and an effort has been made understand the impact of plastics on environmental and health impact considering the physical and chemical properties of plastics and issues associated with their biodegradability. Finally, the management strategies by recycling, depolymerization, bioremediation and upcycling have been reflected. From these studies, it may be concluded that as compared to the conventional recycling methods, the upcycling methods results in high quality end products with potential for advanced applications. Moreover, valourization of plastic wastes to energy fuels, chemicals and macromolecules not only minimizes the unwanted side products but also drastically reduces energy consumption. Upcycling methods have increased conversion efficiency to a greater extent and have proven their superiority in handling contaminated plastic by decreasing process complexity. Upcycling by catalytic degradation and depolymerization processes target towards setting a sustainable and much superior method of reducing half-life and undesired products. In attaining the specified goals, some of the promising options are the development of catalysts such as quantum dot, enzyme mimetic, homogenous and tandem catalysis strategies as well as stabilization chemistry. Catalysts with high tolerance for moisture, air and contaminants such as organic or metallic salts are potential options for solving the bottlenecks in valuation pathway. Furthermore, as a result of integration of technologies for upcycling of plastics with oil refining, biorefinery and processes of use of CO2, and strategies like chemical bond activation, enzymatic decomposition mechanism and photoreforming process, the upcycling process has found successful application in conversion of plastic and biomass to much valuable products. Though numerous recycling and depolymerization methods have been designed at laboratory condition from renewable sources, but an ideal integration of sustainability, degradability at low cost is still a big challenge. Therefore, much effort is required for the development of more selective and speedy degradation technologies.

References [1] A.K. van der Vegt, From Polymers to Plastics, VSSD, 2002, p. 268. Available from: http://www.vssd.nl/hlf/ m008.htm, http://www.vssd.nl/hlf/m028.htm. [2] M. Gilbert, Plastics materials: introduction and historical development, Brydson’s Plastics Materials,, eighth ed., Elsevier, 2016, pp. 2 18. Available from: https://doi.org/10.1016/B978-0-323-35824-8.00001-3. [3] S. Huang, H. Wang, W. Ahmad, A. Ahmad, N. Ivanovich Vatin, A.M. Mohamed, et al., Plastic waste management strategies and their environmental aspects: a scientometric analysis and comprehensive review, Int. J. Environ. Res. Public. health 19 (8) (2022) 4556. Available from: https://doi.org/10.3390/ijerph19084556.

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References

353

[4] S.A. Mason, D. Garneau, R. Sutton, Y. Chu, K. Ehmann, J. Barnes, et al., Microplastic pollution is widely detected in US municipal wastewater treatment plant effluent, Environ. Pollut. (Barking, Essex: 1987) 218 (2016) 1045 1054. Available from: https://doi.org/10.1016/J.ENVPOL.2016.08.056. [5] J.N. Hahladakis, C.A. Velis, R. Weber, E. Iacovidou, P. Purnell, An overview of chemical additives present in plastics: migration, release, fate and environmental impact during their use, disposal and recycling, J. Hazard. Mater. 344 (2018) 179 199. Available from: https://doi.org/10.1016/J.JHAZMAT.2017.10.014. [6] D. Hoornweg, P. Bhada-Tata, What a waste: global review 2012. World Bank, Washinton DC, 2012. [7] A.L. Andrady, M.A. Neal, Applications and societal benefits of plastics, Philos. Trans. R. Soc. B: Biol. Sci. 364 (1526) (2009) 1977 1984. Available from: https://doi.org/10.1098/RSTB.2008.0304. [8] Y.B. Sonawane, M.R. Shindikar, M.Y. Khaladkar, Onsite conversion of thermoplastic waste into fuel by catalytic pyrolysis, Int. J. Innovative Res. Science, Eng. Technol. (An. ISO) 3297 (9) (2007) 2319 8753. Available from: https://doi.org/10.15680/IJIRSET.2014.0309016. [9] J. Hopewell, R. Dvorak, E. Kosior, Plastics recycling: challenges and opportunities, Philos. Trans. R. Soc. B: Biol. Sci. 364 (1526) (2009) 2115 2126. Available from: https://doi.org/10.1098/RSTB.2008.0311. [10] K. Ragaert, L. Delva, K. Van Geem, Mechanical and chemical recycling of solid plastic waste, Waste Manag. 69 (2017) 24 58. Available from: https://doi.org/10.1016/J.WASMAN.2017.07.044. [11] C. Renee, The truth about bioplastics. https://news.climate.columbia.edu/2017/12/13/the-truth-about-bioplastics/, 2022 (retrieved 04.07.22). [12] T. Narancic, S. Verstichel, S. Reddy Chaganti, L. Morales-Gamez, S.T. Kenny, B. De Wilde, et al., Biodegradable plastic blends create new possibilities for end-of-life management of plastics but they are not a panacea for plastic pollution, Environ. Sci. & Technol. 52 (18) (2018) 10441 10452. Available from: https:// doi.org/10.1021/ACS.EST.8B02963. [13] C.C. Chen, L. Dai, L. Ma, R.T. Guo, Enzymatic degradation of plant biomass and synthetic polymers, Nat. Rev. Chem. 4 (3) (2020) 114 126. Available from: https://doi.org/10.1038/s41570-020-0163-6. 2020 4:3. [14] G.W. Coates, Y.D.Y.L. Getzler, Chemical recycling to monomer for an ideal, circular polymer economy, Nat. Rev. Mater. 5 (7) (2020) 501 516. Available from: https://doi.org/10.1038/s41578-020-0190-4. 2020 5:7. [15] J.J. Klemeˇs, Y. Fan, Van, R.R. Tan, P. Jiang, Minimising the present and future plastic waste, energy and environmental footprints related to COVID-19, Renew. Sustain. Energy Rev. 127 (2020) 109883. Available from: https://doi.org/10.1016/J.RSER.2020.109883. [16] R. Wei, T. Tiso, J. Bertling, K. O’Connor, L.M. Blank, U.T. Bornscheuer, Possibilities and limitations of biotechnological plastic degradation and recycling, Nat. Catal. 3 (11) (2020) 867 871. Available from: https:// doi.org/10.1038/s41929-020-00521-w. 2020 3:11. [17] C.N. Pe´pin, C. Abou, E. Pe´pin, V. Nault, L. Valiquette, Health-care waste, https://www.who.int/newsroom/fact-sheets/detail/health-care-waste, 2022 (retrieved 04.07.2022). [18] H.B. Sharma, K.R. Vanapalli, V.S. Cheela, V.P. Ranjan, A.K. Jaglan, B. Dubey, et al., Challenges, opportunities, and innovations for effective solid waste management during and post COVID-19 pandemic, Resources, Conservation, Recycling (2020) 162. Available from: https://doi.org/10.1016/J.RESCONREC. 2020.105052. [19] N.U. Benson, O.H. Fred-Ahmadu, D.E. Bassey, A.A. Atayero, COVID-19 pandemic and emerging plasticbased personal protective equipment waste pollution and management in Africa, J. Environ. Chem. Eng. 9 (3) (2021) 105222. Available from: https://doi.org/10.1016/J.JECE.2021.105222. [20] J.M. Garcı´a, Catalyst: design challenges for the future of plastics recycling, Chem 1 (6) (2016) 813 815. Available from: https://doi.org/10.1016/J.CHEMPR.2016.11.003. [21] X. Sun, M. Chwatko, D.H. Lee, J.L. Bachman, J.F. Reuther, N.A. Lynd, et al., Chemically triggered synthesis, remodeling, and degradation of soft materials, J. Am. Chem. Soc. 142 (8) (2020) 3913 3922. Available from: https://doi.org/10.1021/JACS.9B12122/SUPPL_FILE/JA9B12122_SI_002.PDF. [22] C. Zhou, W. Fang, W. Xu, A. Cao, R. Wang, Characteristics and the recovery potential of plastic wastes obtained from landfill mining, J. Clean. Prod. 80 (2014) 80 86. Available from: https://doi.org/10.1016/J. JCLEPRO.2014.05.083. [23] J.R. Seay, W-T. Chen, M.E. Ternes, Waste plastic: challenges and opportunities for the Chemical Industry AIChE, https://www.aiche.org/resources/publications/cep/2020/november/waste-plastic-challenges-andopportunities-chemical-industry, 2022 (retrieved 04.07.22).

Green Chemistry Approaches to Environmental Sustainability

354

15. Depolymerization of waste plastics and chemicals

[24] R. Geyer, J.R. Jambeck, K.L. Law, Production, use, and fate of all plastics ever made, Sci. Adv. 3 (7) (2017). Available from: https://doi.org/10.1126/SCIADV.1700782/SUPPL_FILE/1700782_SM.PDF. [25] A. David, O. Oluwayomi Joel, Design and construction of a plastic shredder machine for recycling and management of plastic wastes, Int. J. Sci. & Eng. Res. 9 (5) (2018). Available from: http://www.ijser.org. [26] L. Lebreton, A. Andrady, Future scenarios of global plastic waste generation and disposal, Palgrave Commun. 5 (1) (2019) 1 11. Available from: https://doi.org/10.1057/s41599-018-0212-7. 2019 5:1. [27] P.O. Awoyera, A. Adesina, Plastic wastes to construction products: Status, limitations and future perspective, Case Stud. Constr. Mater. 12 (2020) e00330. Available from: https://doi.org/10.1016/J.CSCM.2020.E00330. [28] R. Miandad, M.A. Barakat, A.S. Aburiazaiza, M. Rehan, A.S. Nizami, Catalytic pyrolysis of plastic waste: a review, Process. Saf. Environ. Prot. 102 (2016) 822 838. Available from: https://doi.org/10.1016/J. PSEP.2016.06.022. [29] M.S. Qureshi, A. Oasmaa, H. Pihkola, I. Deviatkin, A. Tenhunen, J. Mannila, et al., Pyrolysis of plastic waste: opportunities and challenges, J. Anal. Appl. Pyrolysis 152 (2020) 104804. Available from: https://doi.org/ 10.1016/J.JAAP.2020.104804. [30] H. Shent, R.J. Pugh, E. Forssberg, A review of plastics waste recycling and the flotation of plastics, Resources, Conserv. Recycling 25 (2) (1999) 85 109. Available from: https://doi.org/10.1016/S0921-3449(98)00017-2. [31] L. De Weerdt, T. Sasao, T. Compernolle, S. Van Passel, S. De Jaeger (2022). The effect of waste incineration taxation on industrial plastic waste generation: a panel analysis. [32] N. Miskolczi, A. Angyal, L. Bartha, I. Valkai, Fuels by pyrolysis of waste plastics from agricultural and packaging sectors in a pilot scale reactor, Fuel Process. Technol. 90 (7 8) (2009) 1032 1040. Available from: https://doi.org/10.1016/J.FUPROC.2009.04.019. [33] C. Netzer, T. Li, T. Løva˚s, Surrogate reaction mechanism for waste incineration and pollutant formation, Energy Fuels 35 (9) (2021) 7030 7049. Available from: https://doi.org/10.1021/ACS.ENERGYFUELS.0C03485/ SUPPL_FILE/EF0C03485_SI_004.TXT. [34] J. Ru, Y. Huo, Y. Yang, Microbial degradation and valorization of plastic wastes, Front. Microbiology 11 (2020) 442. Available from: https://doi.org/10.3389/FMICB.2020.00442/BIBTEX. [35] D.K.A. Barnes, F. Galgani, R.C. Thompson, M. Barlaz, Accumulation and fragmentation of plastic debris in global environments, Philos. Trans. R. Soc. B: Biol. Sci. 364 (1526) (2009) 1985 1998. Available from: https:// doi.org/10.1098/RSTB.2008.0205. [36] Elahi A. Zeenat, D.A. Bukhari, S. Shamim, A. Rehman, Plastics degradation by microbes: a sustainable approach, J. King Saud. Univ. - Sci. 33 (6) (2021) 101538. Available from: https://doi.org/10.1016/J. JKSUS.2021.101538. [37] R.V. Moharir, S. Kumar, Challenges associated with plastic waste disposal and allied microbial routes for its effective degradation: a comprehensive review, J. Clean. Prod. 208 (2019) 65 76. Available from: https://doi. org/10.1016/J.JCLEPRO.2018.10.059. [38] S. Mukherjee, S. Chatterjee, Microorganisms isolated from hydrocarbon effluent enriched soil, Int.J.Curr. Microbiol.App.Sci 3 (5) (2014) 318 325. Available from: http://www.ijcmas.com. [39] J.E. Pegram, A.L. Andrady, Outdoor weathering of selected polymeric materials under marine exposure conditions, Polym. Degrad. Stab. 26 (4) (1989) 333 345. Available from: https://doi.org/10.1016/0141-3910(89)90112-2. [40] M. Asgher, I. Nasir, N. Khalid, S.A. Qamar, Development of biocomposites based on bacterial cellulose reinforced delignified rice husk-PVA plasticized with glycerol, J. Polym. Res. 27 (11) (2020). Available from: https://doi.org/10.1007/S10965-020-02314-Y. [41] S.A. Qamar, M. Asgher, M. Bilal, Sustainable production, optimization, and partial characterization of exopolysaccharides by Macrococcus brunensis, Waste Biomass Valoriz. 12 (12) (2021) 6847 6859. Available from: https://doi.org/10.1007/S12649-021-01479-X. [42] S.A. Qamar, M. Qamar, M. Bilal, R.N. Bharagava, L.F.R. Ferreira, F. Sher, et al., Cellulose-deconstruction potential of nano-biocatalytic systems: a strategic drive from designing to sustainable applications of immobilized cellulases, Int. J. Biol. Macromolecules 185 (2021) 1 19. Available from: https://doi.org/10.1016/J. IJBIOMAC.2021.06.079. [43] M.A. Hillmyer, The promise of plastics from plants, Sci. (N. York, N.Y.) 358 (6365) (2017) 868 870. Available from: https://doi.org/10.1126/SCIENCE.AAO6711. [44] H. Sardon, A.P. Dove, Plastics recycling with a difference, Sci. (N. York, N.Y.) 360 (6387) (2018) 380 381. Available from: https://doi.org/10.1126/SCIENCE.AAT4997.

Green Chemistry Approaches to Environmental Sustainability

References

355

[45] I. Vollmer, M.J.F. Jenks, M.C.P. Roelands, R.J. White, T. van Harmelen, P. de Wild, et al., Beyond mechanical recycling: giving new life to plastic waste, Angew. Chem. (Int. Ed. Engl.) 59 (36) (2020) 15402 15423. Available from: https://doi.org/10.1002/ANIE.201915651. [46] Y. Zhu, C. Romain, C.K. Williams, Sustainable polymers from renewable resources, Nature 540 (7633) (2016) 354 362. Available from: https://doi.org/10.1038/nature21001. 2016 540:7633. [47] A. Kumar, N. Von Wolff, M. Rauch, Y.Q. Zou, G. Shmul, Y. Ben-David, et al., Hydrogenative depolymerization of nylons, J. Am. Chem. Soc. 142 (33) (2020) 14267 14275. Available from: https://doi.org/10.1021/JACS.0C05675. [48] M. Mehrabzadeh, S.T. Shodjaei, M. Khosravi, Chemical recycling of polyethylene terephthalate, Iran. Polym. J. (Engl. Ed.) 9 (1) (2000) 37 40. [49] T. Wei, Z. Zhang, Z. Zhu, X. Zhou, Y. Wang, Y. Wang, et al., Recycling of waste plastics and scalable preparation of Si/CNF/C composite as anode material for lithium-ion batteries, Ionics 25 (4) (2019) 1523 1529. Available from: https://doi.org/10.1007/S11581-019-02892-Y. [50] J. Min, X. Wen, T. Tang, X. Chen, K. Huo, J. Gong, et al., A general approach towards carbonization of plastic waste into a well-designed 3D porous carbon framework for super lithium-ion batteries, Chem. Commun. 56 (64) (2020) 9142 9145. Available from: https://doi.org/10.1039/D0CC03236K. [51] A. Tennakoon, X. Wu, A.L. Paterson, S. Patnaik, Y. Pei, A.M. LaPointe, et al., Catalytic upcycling of highdensity polyethylene via a processive mechanism, Nat. Catal. 3 (11) (2020) 893 901. Available from: https:// doi.org/10.1038/s41929-020-00519-4. 2020 3:11. [52] S. Lu, Y. Jing, B. Feng, Y. Guo, X. Liu, Y. Wang, H2-free plastic conversion: converting PET back to BTX by unlocking hidden hydrogen, ChemSusChem 14 (19) (2021) 4242 4250. Available from: https://doi.org/ 10.1002/CSSC.202100196. [53] A.A. Peterson, F. Vogel, R.P. Lachance, M. Fro¨ling, M.J. Antal, J.W. Tester, Thermochemical biofuel production in hydrothermal media: a review of sub- and supercritical water technologies, Energy & Environ. Sci. 1 (1) (2008) 32 65. Available from: https://doi.org/10.1039/B810100K. [54] I. Vollmer, M.J.F. Jenks, R. Mayorga Gonza´lez, F. Meirer, B.M. Weckhuysen, Plastic waste conversion over a refinery waste catalyst, Angew. Chem. - Int. Ed. 60 (29) (2021) 16101 16108. Available from: https://doi. org/10.1002/ANIE.202104110. [55] D. Guironnet, B. Peters, Tandem catalysts for polyethylene upcycling: a simple kinetic model, J. Phys. Chem. A 124 (19) (2020) 3935 3942. Available from: https://doi.org/10.1021/ACS.JPCA.0C01363/ASSET/ IMAGES/MEDIUM/JP0C01363_0009.GIF. [56] G. Elordi, M. Olazar, G. Lopez, M. Amutio, M. Artetxe, R. Aguado, et al., Catalytic pyrolysis of HDPE in continuous mode over zeolite catalysts in a conical spouted bed reactor, J. Anal. Appl. Pyrolysis 85 (1 2) (2009) 345 351. Available from: https://doi.org/10.1016/J.JAAP.2008.10.015. [57] Y. Ishihara, H. Nanbu, K. Saido, T. Ikemura, T. Takesue, T. Kuroki, Mechanism of gas formation in catalytic decomposition of polypropylene, Fuel 72 (8) (1993) 1115 1119. Available from: https://doi.org/10.1016/ 0016-2361(93)90318-V. [58] B.K. Sharma, B.R. Moser, K.E. Vermillion, K.M. Doll, N. Rajagopalan, Production, characterization and fuel properties of alternative diesel fuel from pyrolysis of waste plastic grocery bags, Fuel Process. Technol. 122 (2014) 79 90. Available from: https://doi.org/10.1016/J.FUPROC.2014.01.019. [59] S. Chaudhary, M. Kumari, P. Chauhan, G. Ram Chaudhary, Upcycling of plastic waste into fluorescent carbon dots: an environmentally viable transformation to biocompatible C-dots with potential prospective in analytical applications, Waste Manag. (N. York, N.Y.) 120 (2021) 675 686. Available from: https://doi.org/ 10.1016/J.WASMAN.2020.10.038. [60] J. Gong, J. Liu, Z. Jiang, X. Chen, X. Wen, E. Mijowska, et al., Converting mixed plastics into mesoporous hollow carbon spheres with controllable diameter, Appl. Catal. B: Environ. 152 153 (1) (2014) 289 299. Available from: https://doi.org/10.1016/J.APCATB.2014.01.051. [61] E. Ba¨ckstro¨m, K. Odelius, M. Hakkarainen, Designed from recycled: turning polyethylene waste to covalently attached polylactide plasticizers, ACS Sustain. Chem. Eng. 7 (12) (2019) 11004 11013. Available from: https://doi. org/10.1021/ACSSUSCHEMENG.9B02092/ASSET/IMAGES/LARGE/SC-2019-02092U_0011.JPEG. [62] H. Jiang, L. Ye, Y. Wang, L. Ma, D. Cui, T. Tang, Synthesis and characterization of polypropylene-based polyurethanes, Macromolecules 53 (9) (2020) 3349 3357. Available from: https://doi.org/10.1021/ACS. MACROMOL.0C00159/SUPPL_FILE/MA0C00159_SI_001.PDF.

Green Chemistry Approaches to Environmental Sustainability

356

15. Depolymerization of waste plastics and chemicals

[63] S. Joo, I.J. Cho, H. Seo, H.F. Son, H.Y. Sagong, T.J. Shin, et al., Structural insight into molecular mechanism of poly(ethylene terephthalate) degradation, Nat. Commun. 9 (1) (2018) 1 12. Available from: https://doi.org/ 10.1038/s41467-018-02881-1. 2018 9:1. [64] P.J. Kim, H.D. Fontecha, K. Kim, V.G. Pol, Toward high-performance lithium-sulfur batteries: upcycling of LDPE plastic into sulfonated carbon scaffold via microwave-promoted sulfonation, ACS Appl. Mater. Interfaces 10 (17) (2018) 14827 14834. Available from: https://doi.org/10.1021/ACSAMI.8B03959/ SUPPL_FILE/AM8B03959_SI_001.PDF. [65] X. Liu, C. Ma, Y. Wen, X. Chen, X. Zhao, T. Tang, et al., Highly efficient conversion of waste plastic into thin carbon nanosheets for superior capacitive energy storage, Carbon 171 (2021) 819 828. Available from: https://doi.org/10.1016/J.CARBON.2020.09.057. [66] K. Jin, P. Vozka, G. Kilaz, W.T. Chen, N.H.L. Wang, Conversion of polyethylene waste into clean fuels and waxes via hydrothermal processing (HTP, Fuel (2020) 273. Available from: https://doi.org/10.1016/J. FUEL.2020.117726. [67] Y. Sakata, M.A. Uddin, K. Koizumi, K. Murata, Catalytic degradation of polypropylene into liquid hydrocarbons using silica-alumina catalyst, Chem. Lett. 3 (1996) 245 246. Available from: https://doi.org/10.1246/CL.1996.245. [68] X. Jia, C. Qin, T. Friedberger, Z. Guan, Z. Huang, Efficient and selective degradation of polyethylenes into liquid fuels and waxes under mild conditions, Sci. Adv. 2 (6) (2016). Available from: https://doi.org/ 10.1126/SCIADV.1501591/SUPPL_FILE/1501591_SM.PDF. [69] F. Zhang, M. Zeng, R.D. Yappert, J. Sun, Y.H. Lee, A.M. LaPointe, et al., Polyethylene upcycling to longchain alkylaromatics by tandem hydrogenolysis/aromatization, Science 370 (6515) (2020). Available from: https://doi.org/10.1126/SCIENCE.ABC5441/SUPPL_FILE/ABC5441_ZHANG_SM.PDF. [70] W.T. Chen, K. Jin, N.H. Linda Wang, Use of supercritical water for the liquefaction of polypropylene into oil, ACS Sustain. Chem. Eng. 7 (4) (2019) 3749 3758. Available from: https://doi.org/10.1021/ ACSSUSCHEMENG.8B03841/SUPPL_FILE/SC8B03841_SI_001.PDF. [71] Y. Miao, A. von Jouanne, A. Yokochi, Current technologies in depolymerization process and the road ahead, Polymers 13 (3) (2021) 1 17. Available from: https://doi.org/10.3390/polym13030449. [72] M. Watanabe, H. Hirakoso, S. Sawamoto, Adschiri Tadafumi, K. Arai, Polyethylene conversion in supercritical water, J. Supercrit. Fluids 13 (1 3) (1998) 247 252. Available from: https://doi.org/10.1016/S0896-8446(98)00058-8. [73] M.S. Seshasayee, P.E. Savage, Oil from plastic via hydrothermal liquefaction: Production and characterization, Appl. Energy (2020) 278. Available from: https://doi.org/10.1016/J.APENERGY.2020.115673. [74] A.C. Albertsson, M. Hakkarainen, Designed to degrade, Sci. (N. York, N.Y.) 358 (6365) (2017) 872 873. Available from: https://doi.org/10.1126/SCIENCE.AAP8115. [75] I. Vollmer, M.J.F. Jenks, M.C.P. Roelands, R.J. White, T. van Harmelen, P. de Wild, et al., Beyond mechanical recycling: giving new life to plastic waste, Angew. Chem. Int. Ed. 59 (36) (2020) 15402 15423. Available from: https://doi.org/10.1002/ANIE.201915651. [76] C. Horejs, Solutions to plastic pollution, Nat. Rev. Mater. 5 (9) (2020) 641. Available from: https://doi.org/ 10.1038/S41578-020-00237-0. [77] M.C. Krueger, H. Harms, D. Schlosser, Prospects for microbiological solutions to environmental pollution with plastics, Appl. Microbiology Biotechnol. 99 (21) (2015) 8857 8874. Available from: https://doi.org/ 10.1007/S00253-015-6879-4. [78] O. Saad Jumaah, Screening of plastic degrading bacteria from dumped soil area, IOSR J. Environ. Sci. 11 (5) (2017) 93 98. Available from: https://doi.org/10.9790/2402-1105029398. [79] A.L. Andrady, Microplastics in the marine environment, Mar. Pollut. Bull. 62 (8) (2011) 1596 1605. Available from: https://doi.org/10.1016/J.MARPOLBUL.2011.05.030. [80] K.L. Law, Plast. Mar. Environ. 9 (1) (2017) 205 229. Available from: https://doi.org/10.1146/ANNUREVMARINE-010816-060409, https://doi.org/10.1146/Annurev-Marine-010816 060409. [81] C.G. Avio, S. Gorbi, F. Regoli, Plastics and microplastics in the oceans: From emerging pollutants to emerged threat, Mar. Environ. Res. 128 (2017) 2 11. Available from: https://doi.org/10.1016/J.MARENVRES.2016.05.012. [82] A.A. Horton, A. Walton, D.J. Spurgeon, E. Lahive, C. Svendsen, Microplastics in freshwater and terrestrial environments: evaluating the current understanding to identify the knowledge gaps and future research priorities, Sci. Total. Environ. 586 (2017) 127 141. Available from: https://doi.org/10.1016/J. SCITOTENV.2017.01.190.

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C H A P T E R

16 Sustainable Development Goals for addressing environmental challenges Chandra Mohan1, Jenifer Robinson2, Lata Vodwal3 and Neeraj Kumari1 1

Department of Chemistry, School of Basic and Applied Sciences, K. R. Mangalam University, Gurugram, Haryana, India 2Department of Science and French, Indian School Al Wadi Al Kabir, Muscat, Sultanate of Oman 3Department of Chemistry, Maitreyi College, New Delhi, India

16.1 Introduction Sustainable development has become the need of the hour. Resources around us are being depleted at unrecoverable rates. It’s high time we learn to use these resources judiciously. This needs to be followed not just in one or two countries, but in all the countries across the world. The United Nations has urged all partner countries to complete 17 Sustainable Development Goals (SDGs) by the end of 2030. All 193 United Nations partner countries have come together to make it possible. The 17 goals that United Nations aims to achieve following [1 3]: Ending poverty in all forms Achieving food security and promoting sustainable agriculture Ensuring healthy living and well-being for all age groups Ensuring equality in education and promoting lifelong learning Achieving gender equality Ensuring availability and sustainable management of water resources Ensuring access to sustainable energy for all Promoting sustainable economic growth, that is, making employment opportunities for all 9. Creating sustainable industrialization 10. Reducing inequality among countries 11. Making human settlements sustainable 1. 2. 3. 4. 5. 6. 7. 8.

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358 12. 13. 14. 15. 16. 17.

16. Sustainable Development Goals for addressing environmental challenges

Ensuring sustainable production and consumption Combating climate change Ensuring sustainable use of marine resources Sustainable management of forests and ecosystems Promoting peaceful and inclusive societies Revamping global partnerships to achieve SDGs

These goals show that the United Nations aims to achieve sustainable living in all different spheres of life. It has not restricted itself to the environment alone. However, the majority of it is related to the environment as all living on this planet is being made possible by the environment and the resources that it provides to us. Therefore, this chapter will focus on the goals targeted at the conservation of natural resources and therefore address some of the most important environmental challenges. These include ensuring that farmers around the world follow sustainable agricultural practices, water resources are being managed sustainably, sustainable energy sources are available for use, sustainable management of marine and forest resources, and combating climate change. To incorporate sustainability in dealing with environmental challenges, we need to switch to a green chemistry approach of dispensing minimum hazardous waste. These include the use of enzymes in place of reagents, using renewable raw materials, etc. Along with adopting green chemistry, we also need to mitigate the already existing pollutants. Microorganisms and plants, with or without manoeuvring, are being looked upon as powerful tools for the removal of pollutants and cleaning of precious resources along with conserving them. Unlike chemical remediation methods, bioremediation is a very environment-friendly approach, leaving nearly zero toxicity behind, and is also relatively inexpensive. For example, the use of corexit in chemical remediation of oil spills leaves behind chemicals that affect life under the ocean, whereas bioremediation of oil spills has shown no potential harm to marine life [4 7].

16.2 Sustainable management of clean water and sanitation Water is one of the most precious resources on this planet. On average, a person uses 101.5 gallons (384.22 L) of water each day [8]. Research at MIT states that consumption of water at the current pace can leave most regions of the earth water stressed by the end of 2050. Water consumption is not as big a problem as the availability of clean water. Increasing consumption and poor water cleaning facilities form a vicious loop. Every year millions of people lose their lives to diseases associated with diarrhoeal conditions caused due to poor drinking water and sanitation facilities. By the end of 2030, the UN partner countries are resolute to provide universal access to clean and safe drinking water and sanitation. They aim to end open defecation across the world. In order to provide safe water facilities, strict monitoring and regulation of waste disposal by industries needs to be done. For this, norms for minimal discharge of hazardous industrial waste need to be laid and strictly implemented. Water use across countries should be made judicious and efficient. To ensure an adequate supply of fresh water, the maintenance of freshwater ecosystem elements, namely, mountains, wetlands, forests, rivers, aquifers, etc., needs to be

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done [9,10]. Developing countries need to focus on water harvesting for capacity building, the development of desalination technologies, and increasing efficiency and standards of wastewater treatment. All this cannot be done by governments alone. Local communities need to be made aware and sensitized towards water management [11].

16.3 Ensuring access to sustainable energy Access to energy is important for the growth and development of a nation. Energy is fuel for cooking, electricity, railways, cars, buses, etc. The challenge is that currently available fuel sources are either not clean (biomass combustion), limited (nuclear), or both (coal). Heart disease, lung and respiratory infection, and even death can result if the cooking fuel emits soot. According to research done in 2016, around 39% of homes are still devoid of clean fuel for cooking. To solve these issues, the world needs to look for renewable and clean sources of energy. Solar energy is one such source. Other examples include wind energy where turbines move due to wind and drive generators. The electricity thus produced is fed into grids. Similarly, the turbine can be moved using water made to fall from a height in a dam. The electricity generated this way is referred to as hydroelectricity. The heat from beneath the earth’s surface can also be used to move the turbine. The electricity thus produced is called geothermal energy. Biomass is also relatively clean keeping in mind that the carbon dioxide being consumed by the plant during its lifetime is nearly equivalent to what it produces when combusted. Therefore, it is a carbon-neutral source of energy. The United Nations aims to ensure universal access to affordable, clean and renewable energy by the end of 2030. The current share of these clean and renewable energy resources in the global mix is only 15%. This needs to be increased substantially by the end of 2030. Before we look into alternative sources of energy, it is important that each and everyone has access to energy and that the current technology is optimized. To achieve this, first, electricity delivery to poor or underdeveloped countries needs to be accelerated as 13% of the world’s population is still devoid of electricity. Secondly, energy efficiency needs to be increased, and lastly, clean, safe and renewable sources of energy need to be explored as around 3 billion people rely on high carbon-emitting sources like wood, coal, charcoal and animal wastes for cooking fuel requirements. These fuels emit harmful greenhouse gases that can be fatal when inhaled excessively. In 2012, around 4.3 million deaths were reported due to respiratory failure associated with the inhalation of these gases. Since most women and girls work in household kitchens, 6 out of 10 deaths were of women or girls. The world is slowly switching to cleaner and renewable sources of energy. These include solar energy, wind energy, hydroelectricity, geothermal energy, etc. Each of these sources has its own advantages and disadvantages. While one can harvest infinite energy from the sun, the capital investment required is quite high. Also, not every place on the planet receives enough sunlight for the generation of the required electricity. Similarly, for wind energy, a huge mass of land is required for the installation of huge windmills. Also, sufficient wind velocity needs to be there to rotate the windmill and therefore the turbines for electricity generation. This comes up as a limitation for not being able to use wind

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energy in places with no or less wind and with low land availability. For hydroelectricity generation, huge dams need to be built so that water falls from a height that is high enough to make the turbine rotate at a high speed for energy generation. Despite these limitations, the above-mentioned sources of energy are clean and renewable. Therefore, if we can overcome the aforementioned challenges, we should definitely switch to these sources. From 2012 to 2016 the share of these renewable natural energy sources in the total energy generation pool increased by 0.24% to reach a total of 17.5%. This has been made possible due to rapid advancement and growth in solar, wind and hydropower energy harvesting technologies.

16.3.1 Building sustainable chemistry to combat climate change In past, water vapour, carbon dioxide, methane and nitrous oxide were the four major naturally occurring greenhouse gases in the Earth’s atmosphere [12,13] of which optimum levels of carbon dioxide contributed as fuels to lush growth and stored in the form of fossil fuels. However, in this industrial era, the percentage of carbon dioxide has increased resulting in the long trapping of carbon dioxide back into the atmosphere making the Earth warmer. Methane is released naturally under the sea beds in the form of methane hydrates and reaches the surface in the form of atmospheric methane, thereby mixing with other greenhouse gases. Nitrous oxides are usually produced by vehicles, burning of fossil fuels and during agricultural practices. Being long-lived, nitrous oxide also contributes significantly to global warming [14,15]. Here is the evidence of climate change challenges faced globally. • The Agassiz Glaciers in Montana and Pasterze Glaciers in Austria melting rapidly are being observed using remote sensing kits by researchers who found that there is a considerable reduction in their surface area since the 19th century [16,17]. • The ice core data from Antarctica and Greenland comparing the variation in temperature due to the high rise of atmospheric carbon dioxide levels help scientists to estimate accurately from centuries ago. • Tree-Ring Data Bank provides sufficient studies on climate change. Variations in the measurement of full ring widths of trees and the nature of primary wood and new growth rings show a warming trend in recent investigations. • The European butterflies are becoming extinct indicating the climatic risk of a 4 C rise, the British birds found migrating towards the north by an average of 19 km, and abnormal flowering of plants at Arnold Arboretum are the predominant signs of startling climate changes. • The first-ever red warning due to remarkable heat forecasted by the UK researchers, increased water demand, a threat to food safety related to heat waves, droughts and other social issues, disappearance of global heritage sites across Europe, alter in bird colouration—are all due to rapid climate change. • Global warnings in Spain as the rate of warming have hastened over the years and France being vulnerable to climate change impact with an increase in temperature, risk of heat radiations, extreme rainfall, floods and severe storms have set a firm policy of a net-zero carbon by 2050.

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• Due to the rapidly growing population and huge dependence on fossil fuels, the climate change estimation report of India discovered that there is an expected temperature rise of 4 C by 2100. • Reporters in 2021 confirmed that China is presently the world’s chief emitter of greenhouse gases and is posing threat to climate change. • The wildfires in Australia, California and Spain were declared among the worst catastrophes in modern climate threats. Climate Action—SDG 13—a call for crucial action not only to fight climate change and its consequences but also to build tolerance towards climate-related calamities (Table 16.1). In 2021, a lot of measures were taken to reduce greenhouse gas emissions towards limiting global warming by 2030 and reaching net-zero carbon emissions by 2050. The COVID19 [18] epidemic considerably decreased human activities in 2020 and 2021 leading to a decrease in GHG emissions by 4%. But as soon as the world improved from the pandemic situation, emissions rose higher than expected and yet again led to challenging tasks for all the researchers towards carbon neutrality. It’s time for every individual to take precautions and adjust to the changing climate which is evident in the form of heat waves, sudden cyclones, droughts, floods, etc. Developed countries should render maximum financial support to developing countries to attain a low-emission and climate-resilient future directed through Green Climate Fund (Table 16.2). The sustainable green chemistry [19] approach will pave the way to take critical action to battle climate change with significant strategies like the establishment of the scientific basis for sustainable management, inculcating scientific understanding among the young buddies and researchers, introducing long-term scientific questionnaires and surveys and structuring up scientific aptitude and competency. Effective utilization of GHGs for the synthesis of novel green material, including carbon dioxide in catalytic reactions, electrochemical, photoelectrochemical and biological conversions of GHGs into synthetic fuels, organic useful and green products and collaboration of sustainable chemists with climate scientists would upkeep the future of the planet Earth to attain net-zero carbon emissions by 2100 [20].

16.3.2 Building a sustainable ecosystem on land The United Nations defines Sustainable Land Management (SLM) as using the present land resources to fulfil human needs while ensuring their long-term productive potential for future generations. Integral landscape management, natural resource management, soil management and water management are part of sustainable land management. Ideal sustainable land management helps maximal economic and social utilization of land along with supporting the land ecologically. The interaction of climate, human activities and land resources determines land management, use and productivity. A few significant principles may help in achieving holistic management of land. These include incentivizing locals to use land resources for profit in return for taking care of the available resources. For example, there are certain regions in the forest that are designated as buffer zones. It is in these regions that locals and abiotic and biotic components of the land ecosystem live in harmony. The locals can take care of the resources and are entitled to use them in order to

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TABLE 16.1 A comparative study of the SDGs progress reports from 2016 to 2020. Climate change Year consequences

New improvements

Sectors to monitor

Projects undertaken

2016 A steady rise in carbon emissions An increase in global temperatures Hottest on record (2011 2015) Reduction in sea ice Coral bleaching Threat to coral reefs

Lessen climate change Low-carbon future Strengthen global responses Identify intended nationally determined contributions (INDCs) Tracking of Global stocktaking exercise every 5 years

Water, agriculture, health, natural disasters

Climate change adaptation, environmental impact assessment, integrated planning

2017 A steady rise in carbon emissions An increase in global temperatures A rise in greenhouse gas emissions One of the three warmest on record

Bring nations together Reduce global temperature rise Climate-resilient pathways Actionable strategies Focus on financial flows, technologies, supporting most vulnerable countries

NDCs related targets & policies Intensive disasters, economic, social, health and environmental resilience

National Adaptation Plan (NAP) Development planning processes and strategies Green Climate Fund Land Management

2018 North Atlantic hurricane season on record Rising sea levels Extreme weather conditions Increasing concentrations of Greenhouse gases (GHGs)

Paris Agreement was World made officially signed by Meteorological the majority of countries systems and NDCs Developed countries to address the needs of developing countries

2019 Atmospheric CO2 reached 405.5 ppm Greenhouse gas emissions

Global carbon emissions to fall by 45% Net-zero emissions by 2050 Investment in disaster risk reduction Investment in renewable energy

Climate-related disasters Sendai Framework

Preparing new NDCs SDGs and climate change coherent plans, third biennial assessment Green Climate Fund Readiness and Preparatory Support Programme, Least Developed Countries

2020 GHG emissions in developing countries are up by 43.2% Increased industrialization Enhanced economic output COVID-19 pandemic situation

Reduction of global warming by 1.5 C Global carbon emissions to fall by 45% NDCs to UNFCCC

COVID-19 pandemic-related areas The energy sectors related to fossil fuels, the severity of natural disasters Sendai Framework

18 National Adaptation plans 2 Adaptation communication plans Green Climate Fund COVID-19 integrates biohazard risk management and risk reduction strategies at the national and local levels

National Adaptation Plans

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Forecast of climate change and climate action.

Climate change

Climate action

• Increased heat waves, droughts and floods • High rise of energy-related carbon dioxide emissions • Frequent climate catastrophes • Global emissions to increase by approximately 15%

• Due to global conflicts, speeding up climate action is a necessary task • Improvised policies on disaster risk reduction plans • Climate-resilient future through appropriate funds

make money. Stakeholders at multiple levels: the land users, technical experts and policymakers should work together for the sustainable management of land. At the level of farmers, practices like the use of natural predators instead of pesticides can help maintain the ecosystem harmony along with keeping the land and water table free from pollution. This way the integrated approach involving multiple strategies should be used to achieve SLM.

16.3.3 Building a sustainable ecosystem in the water Water is one of the most precious resources on this planet. One cannot imagine life without water. Water is used everywhere: from everyday chores like bathing, washing, etc. to industries that use water as a raw material or coolant, for irrigation of crops, and most importantly for drinking. There is no alternative to water. The rate at which we consume water is way more than the rate at which our treatment plants can clean it for reuse. This way ends up degrading water quality with use. This can, in the future, lead to an increase in cases of water-borne diseases. These can be fairly dealt with if we increase the efficiency of wastewater treatment plants. One can do this by upgrading the techniques and technologies being used by a plant. But despite all the technological advancements applied, one cannot treat water beyond a limit. Therefore, water conservation is something that should always be followed. There are several ways that we can conserve water. Both of the strategies adopted together can help maintain sustainable water management. A sustainable ecosystem can be maintained in the water bodies if certain principles are followed. These include no regulated discharge of chemicals in the water bodies, rainwater harvesting for the creation of more water bodies, using drip irrigation if possible, and using organic insecticides and pesticides so that the water table is not polluted. Also, practices like not fishing during monsoons or around the time when the aquatic animals breed can help maintain and enrich the species’ richness and diversity.

16.3.4 Ensuring the availability of cleaner fuel choices Apart from electricity-generating sources, we should also start looking into cleaner petroleum alternatives. Biofuels can provide us with a cleaner alternative. Essentially biofuels are liquid or gaseous fuels made from biomass. Wood, biogas, ethanol and biodiesel are a few examples of biofuels. Unlike petroleum products, biofuels are biodegradable. Based on the feedstock and production process, biofuels are divided into first generation, second generation and third generation biofuels (Table 16.3).

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TABLE 16.3 Types of biofuels. Category

Biofuel

Feedstock

Production process

First generation

Biobutanol

Sugar crops

Fermentation

Biodiesel

Oil crops

Transesterification

Bioethanol

Sugar crops

Fermentation

Bioethanol

Lignocellulosic materials

Enzymatic hydrolysis and fermentation

Biomethanol

Lignocellulosic materials

Gasification, catalytic cracking

Dimethyl ether

Lignocellulosic materials

Gasification, catalytic cracking

Biogas

Lignocellulosic materials

Gasification, catalytic cracking

Biohydrogen

Lignocellulosic materials

Gasification, catalytic cracking

Vegetable oil/biodiesel

Algae

Transesterification

Second generation

Third generation

16.3.5 Building next-generation energy sources 16.3.5.1 Next-generation fuels Hydrogen technology [21] involves the transformation of hydrocarbon-based power generation into hydrogen-based energy production. The new innovative next-generation hydrogen fuel cell electric vehicles (HFCEVs) would be a feasible substitute for the overall fuel problems faced by the world. When hydrogen gas is mixed with air, the chemical energy released could produce approximately 60% efficient electrical energy. These hydrogen-powered electric vehicles could drive about 600 km with zero carbon emissions in the future. “Hydrogen economy” refers to the consumption of hydrogen gas as a commercial fuel and made available for hydrogen technology abiding by government plans and policies. The solar-powered water electrolysis plants, the establishment of hydrogen refuelling stations, the development of the infrastructure of hydrogen stations, the manufacture of HFCEVs in enormous quantities, government investments, etc. are the signs of electric competition with cost-effective and more efficient HFCEVs in the business market and would changeover hydrocarbon-based technology shortly [14] (Fig. 16.1). In the Sultanate of Oman, green fuel developers [15] are working towards zero-carbon green hydrogen using renewable solar and wind energy sources. Synthetic fuels made from green hydrogen would support to a larger extent in the transportation sectors. The brine from the seawater will act as the major intake for electrolysis to produce clean energy at a scale that is cost-competitive with fossil fuels significantly prioritizing the reduction in global greenhouse emissions, environmental and social considerations, financial standards and finally creating positive returns to the next-generation society [12]. 16.3.5.2 Next-generation sustainable batteries A revolution has been noticed in battery research in the last decade, especially in the development of Li-ion batteries [13]. Nowadays, several industries are working constantly to ensure battery development, technologies, lasting supply plans, maximum protection

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FIGURE 16.1 Splitting of water molecules into hydrogen and oxygen gases.

measures in manufacturing sectors, energy competence, transportation and applications of sustainable batteries. Lithium is a common element with the chemical symbol Li. Its atomic number (Z) is 3. It is a soft, silvery-white alkali light metal. Li-ion battery [16] is a rechargeable battery available in many different shapes and sizes. Each cell comprises the following battery materials. The carbon rod with packed lithium as the anode whereas lithium oxide is the cathode. From the anode, the lithium ions are carried by the electrolyte to the cathode and vice versa with the help of the separator. Thus, the charging or discharging of the gadgets is fully controlled by the movement of the lithium ions. The main advantages of lithium-ion batteries are tiny in size, are lighter, have remarkable energy storage, are ecofriendly and have long lifespans and hence found applications in health care devices like pacemakers, wearable biosensors, surgical tools, gastric stimulators and medical device monitors. Metal-air batteries [17], the better performance with greater energy storage capacity, are completely safe, cheap and mechanically rechargeable with a longer lifetime. More research projects are in progress to resolve the unwanted crystal growth which decreases the efficiency of these batteries. Overcoming this issue, metal-air batteries could provide a better battery source for electric vehicles in place of the present gasoline and diesel (Fig. 16.2). In Oman, the support for secure recycling of lead-acid batteries by green chemists to protect the environment for a better world today and in the future. These batteries will be recycled into sustainable products thereby conserving nature for next-generation humanity [12]. 16.3.5.3 Next-generation waste-to-recyclates Generally, the rotor blades of wind turbines are made of fibre-reinforced plastics (FRPs) which cannot be recycled easily. This leads to an enormous global environmental problem and the accumulation of total waste resources. Blade recycling [14] is a top priority for the

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FIGURE 16.2 The working of a metal-air battery.

wind energy production industries. Though lighter and longer wind turbine blades made from FRP materials show a considerable performance of wind energy production globally, the landfilling of these blades has led to extreme environmental discussions in the present era. The introduction of patented low-cost agglomeration technology to employ recycled FRP wastes [22] obtained from wood wastes, plastics Polyethylene (PE) or Polypropylene (PP) wastes, glass FRP wastes and additives through various processes like shredding, regrinding and compounding. The eco-bulk composite panels become stronger, stiffer and more cost-effective as compared to traditional non-recyclable FRPs [23] (Fig. 16.3). In Oman [24], an investigation is in progress on the existing recycling methods of rotor blades through co-processing in the cement industry which is the only economical option at present for handling large amounts of waste materials. The End-of-Life (EoL) wind turbine blades could be recycled by three major practices—mechanical recycling, thermal recycling and chemical recycling. Chemical recycling involves the processes like solvolysis and high voltage pulse fragmentation. In solvolysis, a suitable solvent (water, alcohol or acid) could break down the crosslinked polymers into recovered FRPs under appropriate temperature and pressure conditions, without much alteration of their properties and obtain viable by-products. In high voltage pulse fragmentation, pressure waves are created that induce fragmentation of thermoset composites into useful next-generation recyclates. 16.3.5.4 Next-generation green catalysts Green catalysts [25] are recoverable chemical substances or easily prepared from readily available substrates that generally lower the activation energy and improve the reaction rates. The conversion of biomass into biogas energy production is facilitated by an enzyme keratinase produced during its fermentation (Fig. 16.4).

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FIGURE 16.3 Recycled fibre-reinforced plastics.

FIGURE 16.4 Conversion of biomass into biofuel energy production.

The keratinase [18] acts as a biodecomposer that involves biomass waste degradation followed by hydrolysation resulting in fractionation into feasible products along with biogas energy production. Table 16.4 represents the list of green catalysts and their specific applications for green energy production.

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TABLE 16.4 List of green catalysts, their properties and catalytic applications. S. no. Green catalysts

Properties

Catalytic applications

1

Mesoporous silica nanomaterials (M41S)

Large surface area, mesoporosity, tunable pore size, pore structure and morphology

Catalytic fast pyrolysis—In this method, undesirable properties of biomass are completely removed to obtain high quality and good yield of biooil for energy production.

2

Molybdenumcontaining SBA-15 mesoporous silica catalysts

Efficient, reusable catalysts with high specific surface area with uniform mesoporous channels

General alcoholysis reaction catalysed by Mo-SBA-15 where molybdenum is loaded in the catalysts enhanced the alcoholysis of cyclohexene oxide with ethanol catalysed by catalyst synthesized under different hydrothermal treatments and containing different amounts of molybdenum.

3

Production of valueadded furans and phenols from biomass through catalytic fast pyrolysis of pine using molybdenum supported on KIT-5 mesoporous silica

3-dimensional pore structures have better mass transfer properties than 2D pore structures. Equivalent to noble metal properties, but cost-effective

Molybdenum has been extensively studied and is widely used in the petroleum industry for fuel upgrading reactions such as hydrodeoxygenation, hydrodenitrogenation and hydrodesulfurization.

4

β-zeolites with silica-toalumina ratios (SAR) ZSM-5

More yield of aromatic hydrocarbons in acid sites

A fully active β-zeolite catalyst forms olefins and aromatic hydrocarbons. Fresh β-zeolites initially form one- and two-ring aromatics and the formation of furans, benzofurans, phenol, cresols and naphthalenols is observed. Further, all catalysts had a similar hydrocarbon/coke branching ratio.

In Oman, biofuels [19] researchers are in progress with projects that involve the conversion of huge tons of biomass into useful green products. The teamwork of experts from nationwide laboratories, research organizations and manufacturing sectors is crucial to moving biofuel energy production technologies into the marketplace. The government plans and policies are keen on the production of various wide-reaching biofuels which are listed in Table 16.5. Biofuels ensure more promising fuel transport at the hard time of declining oil fields worldwide to safeguard the next-generation demands. 16.3.5.5 Next-generation green ammonia The real answer to more sustainable green energy production is “green ammonia synthesis” [20] to reach net-zero carbon emissions. Mostly, agricultural wastes may contain a high percentage of nitrogen content which could be used for ammonia production. Even though during ammonia production, there is a substantial release of greenhouse gases, keeping in mind to tackle the global carbon challenge, research on green ammonia production agrees internationally to get reasonable and cost-effective clean energy shortly. The availability of almost 78% of the nitrogen in the atmospheric air triggers green chemists to produce green ammonia without the use of coal and petroleum. Finally, the

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TABLE 16.5

The list of biofuels, their sources and advantages.

Biofuels

Biomass sources

Advantages

Ethanol

Corn, sugarcane, sawdust and agricultural wastes

• Highly renewable • Blending gasoline with high octane

Green diesel

Vegetable wastes, crude oil

• Increased lubricity • Reduction in toxic emissions

Butanol

Corn, wheat, sugarcane

• • • •

Hydrocarbons

All types of carbohydrates

• Synthetic gasoline using green catalysts

Jet fuel extracts

Microalgae

• High yield of biofuels • Reuse and carbon dioxide capture

Low volatility High energy density Water tolerant Alternate fuel

FIGURE 16.5 Production of green ammonia.

production is carbon-free ammonia and the result is the major raw material for green fertilizers [26,27]. In the Sultanate of Oman, green ammonia is the most competitive technology, with small-scale plant establishment, high reliability, reduction in carbon footprints, and collaboration of electrolysis of water with existing nitric acid and urea technologies. Overall, green ammonia [28] producers are still working significantly on high yields with minimum functioning expenses (Fig. 16.5).

16.4 Bioremediation and phytoremediation Bioremediation is essentially making use of living organisms for the removal of pollutants and toxins. The living organisms are usually bacteria and microbes which are used with or without encapsulation. The normal metabolism of these microbes is generally the trait that is exploited. The pollutants in this case act as the carbon source for the microbes. The microbe acts on them to convert or digest the waste to its simpler forms. Also, sometimes these microbes are armed with certain specific genes to digest pollutants that may

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not be a part of their normal metabolism. It is then that recombinant DNA technology comes into play. At some site in the microbial plasmid or genomic DNA the degrading gene is inserted. The recombinants are selected and left at the site where toxins or pollutants are accumulated. The microbe now easily acts upon the pollutant and degrades it. This site could be a landfill site where lots of garbage has accumulated over years and a part of it has never degraded. It could also be the effluent sites of various industries like textile, leather, etc. that release harmful non-degradable substances into the environment. This problem especially persists with the dyes used in textile industries. The aromatic dyes don’t degrade beyond a point and have become a major pollutant of surrounding water bodies. Microbes can be encapsulated and left in these water bodies for curation. Bioremediation is of three types, namely biostimulation, intrinsic bioremediation and bioaugmentation. In biostimulation, the microbes in their natural habitat are used to clean up their immediate surroundings. These microbes are supported by providing nutrient media from outside which can help stimulate their growth. In bioaugmentation, on the other hand, microbes from outside are introduced at a site for cleanup. In places where leaks are difficult to detect or underground spots, the remediation that is employed is referred to as intrinsic bioremediation. Bioremediation is done either in situ, that is, at the contamination site or ex situ, that is, when contaminated material is moved from the contamination site to the treatment site. Phytoremediation is another technique that can be used for similar purposes. Phytoremediation is defined as the use of green plants for the removal of toxins and pollutants from the environment. An extended definition of phytoremediation employs the microbes associated with the plant along with the plant for the removal of pollutants. Plants like Cannabis sativa and populus are accumulators of heavy metals in soil [29]. Another example of phytoremediation could be the use of agricultural wastes like sugarcane bagasse, orange peels, etc. in the absorption of dyes and heavy metal wastes in water. This way we could not only treat the polluted water, but also effectively manage agricultural waste that could otherwise land in a dumping site.

16.4.1 Advantages of bioremediation and phytoremediation The usage of easily cultural microbes and aggressively growing plants (or low maintenance species) for the removal of wastes has proven to be cost-effective over other techniques. These techniques are environmentally friendly and help in effective waste management and remediation. The plants grown as hyperaccumulators for the removal of toxins and wastes can be further used for biofuel production. For example, sorghum accumulates phosphorus and can be converted to a biofuel intermediate thereafter by pyrolysis-gas chromatography. Bioremediation and/or phytoremediation can also be used to clean up petroleum products. Farms using excessive chemical pesticides and insecticides can make use of bioremediation strategies for maintaining a sustainable ecosystem. Also, the lumber processing plants make use of wood preservatives which leach into groundwater and soil thereby polluting them. Bioremediation can be employed at these sites for pollution control. With zero side effects, bioremediation and phytoremediation stand as the safest, clean and minimally invasive waste treatment strategies. No large and not many equipment are required to carry out the processes. Little or no energy is

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consumed in these processes as compared to incineration. Public acceptance of such techniques is high as they are purely organic and involve no disturbance. Using in situ bioremediation offers the advantage of not moving the contaminated material from the contamination site to some treatment site. Also, mostly these remediation strategies offer the advantage of complete destruction or conversion of a harmful substance to a harmless substance. This means that no further treatment needs to be administered [30,31].

16.5 Application of biotechnology in achieving Sustainable Development Goals and mitigating environmental challenges Biotechnology is a branch of science that makes use of living organisms and products of living organisms to achieve the desired objective. In each of the SDGs, biotechnology can come up with innovative achievable solutions. Since biotechnology revolves around living organisms, the solutions offered would be clean, safe and environment-friendly. For cleaner water, biotechnology has tools like bioremediation and phytoremediation to its dispense. There are microbes that release enzymes for the digestion of harmful cenobitic wastes in the wastewater. Several biosorbents are available that can be used to adsorb heavy metals, dyes, oil, etc., from wastewater and render it clean. Similarly, biotechnology can also help in providing economical energy resources. Biomass combustion can be made cost-effective if techniques like micropropagation are used. Cleaner landmass can be rendered by the use of bio- and photoremediation. Land and water ecosystems are maintained if we use biotechnology for making innovative alternatives to chemicals. For example, in agriculture, one can incorporate insect resistant or pest-resistant genes into the crop itself so that reliance on insecticides and pesticides is decreased. Recombinant technology comes into play in strengthening the remediating properties of microbes and plants [32]. This way biotechnology has a lot to offer. Aligning resources for supporting research and development in the field of biotechnology can help make SDGs more achievable and with the least harm to the environment.

16.6 Case studies A lot of researchers have done actual field work supporting various environmentfriendly solutions for sustainable management of the ecosystem. One of the earliest works includes the invention of bioremediation. This was done in the 1960s by George Robinson who could experimentally suggest a microbe mix in water that was polluted by petroleum discharge in California where he worked as a petroleum engineer. It was sometime later that another scientist Dr. Anand Mohan Chakraborty filed a patent for the invention of a genetically modified organism that could clear oil spills. It was Pseudomonas putida, a hydrocarbon (especially toluene) degrading bacteria. Dr. Anand Chakraborty was awarded the Nobel prize for the same in the year 1980. It was the first ever issued bacterial patent. In the late 90s, a company named Phytotech used hemp plants for toxin removal. It planted these in several polluted sites in Ukraine, including the Chernobyl site which was

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contaminated with radioactive waste. Also, the remediating action of hemp was seen in Australia, where the fields were rendered useless and contaminated due to mining activities. At around the same time, Berkheya coddii was used in South Africa for the treatment of soil contaminated with nickel. Each plant could absorb nickel equal to 2% 3% of its dry weight. In the Al-Najah province in Saudi Arabia, it was seen that silver levels in soil decreased from 3.31 to 2.56 ppm in areas where Atriplex nummularia was planted. Mustard or Brassica juncea is also used as a hyperaccumulator for remediating soil with lead. Its use has also been tested for the removal of gold like heavy metals from mining sites.

16.7 Conclusion In 2015, the United Nations member countries adopted 17 SDGs, which are a blueprint for a prosperous planet, now and in the future. They aim to achieve these goals by the end of 2030. The key prospects of these goals include the conservation of the environment, building a healthy ecosystem on land and in the water, reducing inequality, providing health and education for all, dealing with climate change and accelerating economic growth. The United Nations brings out an SDG progress report each year to highlight its achievements in this direction. The latest report (June, 2022) puts forward some of the following statistics: • The global poverty has decreased from 10.1% in 2015 to 9.2% in 2020. • Unfortunately, the number of people suffering from food insecurity is rising. This is attributed to the pandemic and the prevailing conditions of war in Ukraine. • From 77% in 2014, now 84% of births are assisted by professionals. • The infant mortality rate fell by 14%, from 43 deaths per 1000 live births in 2015 to 17 deaths per 1000 live births in 2020. • The adolescent birth rate has decreased from 56 births per thousand adolescents (15 19 years of age) to 41 births per thousand adolescents. • Deaths due to AIDS-related causes have declined by 39%. • The incidence of tuberculosis (TB) infection is decreasing by 2% each year. Between 2018 and 2020, the treatment for TB reached 20 million people. • The deaths related to non-communicable diseases have declined from 19.9% to 17.8%. • The percentage of people completing upper secondary school increased from 54% in 2015 to 58% in 2020. • From 2010 to 2020, the number of households gaining access to electricity has increased by 8% (from 83% to 91%). • The forest cover area fell from 31.9% in 2000 to 31.2% in 2020. • The global homicide has declined by 5.2%.

References [1] United Nations, Transforming our world: The 2030 agenda for sustainable development | department of economic and social affairs. United Nations, n.d., from https://sdgs.un.org/2030agenda (retrieved 21.06.22).

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References

373

[2] P. Kaur, S. Sharma, F.M. Albarakaty, A. Kalia, M.M. Hassan, K.A. Abd-Elsalam, Biosorption and bioleaching of heavy metals from electronic waste varied with microbial genera, Sustainability 14 (2022) 935. Available from: https://doi.org/10.3390/su14020935. [3] S.J. Arantza, M.R. Hiram, K. Erika, M.N. Cha´vez-Avile´s, J.I. Valiente-Banuet, G. Fierros-Romero, Bio- and phytoremediation: plants and microbes to the rescue of heavy metal polluted soils, SN Appl. Sci. 4 (2022). Available from: https://doi.org/10.1007/s42452-021-04911-y. [4] D.P. Silva, H.D.M. Villela, H.F. Santos, G.A.S. Duarte, J.R. Ribeiro, A.M. Ghizelini, et al., Multi-domain probiotic consortium as an alternative to chemical remediation of oil spills at coral reefs and adjacent sites, Microbiome 9 (2021). Available from: https://doi.org/10.1186/s40168-021-01041-w. [5] M.U. Siqueira, B. Contin, P.R.B. Fernandes, R. Ruschel-Soares, P.U. Siqueira, J. Baruque-Ramos, Brazilian agro-industrial wastes as potential textile and other raw materials: a sustainable approach, Mater. Circular Economy 4 (2022). Available from: https://doi.org/10.1007/s42824-021-00050-2. [6] A. Saravanan, P.S. Kumar, S. Jeevanantham, P. Harikumar, V. Bhuvaneswari, S. Indraganti, Identification and sequencing of bacteria from crop field: application of bacteria—agro-waste biosorbent for rapid pesticide removal, Environ. Technol. & Innov. 25 (2022) 102116. Available from: https://doi.org/10.1016/j. eti.2021.102116. [7] D.T.C. Nguyen, T.V. Tran, P.S. Kumar, A.T.M. Din, A.A. Jalil, D.V.N. Vo, Invasive plants as biosorbents for environmental remediation: a review, Environ. Chem. Lett. (2022). Available from: https://doi.org/10.1007/ s10311-021-01377-7. [8] Gallons used per person per day - Philadelphia, n.d., from https://water.phila.gov/pool/files/home-wateruse-ig5.pdf (retrieved 20.06.22) [9] C. Mohan, N. Kumari, J. Robinson, Sustainable and environmental friendly energy materials, Mater. Today: Proc. 69 (2022) 494 498. [10] C. Mohan, N. Kumari, Synthesis of acid activated and silicotungstic acid (STA) intercalated montmorillonite clay as green catalyst, Mater. Today: Proc. 56 (2022) 971 975. [11] United Nations, Clean water and sanitation projects | SDG 6 UN India. United Nations, n.d., from https://in.one.un.org/page/sustainable-development-goals/clean-water-sanitation-sdg-6/ (retrieved 20.06.22). [12] P. Calliope, G. Sonja, K. Paraskevi, Advanced biofuels to decarbonize European transport by 2030: Markets, challenges, and policies that impact their successful market uptake, Energy Strategy Rev. 34 (2021) 100633. [13] H. Yang, Z. Sida, H. Yi, Sustainable value chain of retired lithium-ion batteries for electric vehicles, J. Power Sources 478 (2020) 228753. [14] A. Al-Hinai, Y. Charabi, S.H.A. Kaboli, Offshore wind energy resource assessment across the Territory of Oman: a spatial-temporal data analysis, Sustainability 13 (2021) 2862. [15] O. Vincent, W. Siebren, B. Kornelis, Fuel cell electric vehicles and hydrogen balancing 100 percent renewable and integrated national transportation and energy systems, Energy Convers. Management: X 9 (2021) 100077. [16] K. Jai, R. Rana, P. Jaewon, Recent progress in sustainable recycling of LiFePO4-type lithium-ion batteries: strategies for highly selective lithium recovery, Chem. Eng. J. 431 (2022) 133993. [17] C. Kai, H. Gang, Z. Xin, Efforts towards practical and sustainable Li/Na-air batteries, Chin. J. Chem. 39 (2021) 32 42. [18] L. Lene, H. Yuhong, K. Peter, Microbial decomposition of keratin in nature—a new hypothesis of industrial relevance, Appl. Microbiol. Biotechnol. 100 (2016) 2083 2096. [19] C. Latafat, M. Haris, V. Archana, Biological degradation of keratin by microbial keratinase for effective waste management and potent industrial applications, Curr. Protein Peptide Sci. 22 (2021). [20] N.L. Richard, B.A. Rene, I. Wilkinson, “Green” ammonia: impact of renewable energy intermittency on plant sizing and levelized cost of ammonia, Ind. Eng. Chem. Res. 57 (2018) 14607 14616. [21] C. Gabriele, I. Gaetano, S. Perathoner, Chemical engineering role in the use of renewable energy and alternative carbon sources in chemical production, BMC Chem. Eng. 1 (2019) 5. [22] A.K. Jassim, Recycling of polyethylene waste to produce plastic cement, Procedia Manuf. 8 (2017) 635 642. [23] R. Helen, B. Steven, M. Jamie, Factors related to recycling plastic packaging in Finland’s new waste management scheme, Waste Manag. 131 (2021) 88 97. [24] H. Chen, K. Wan, Z. Yayun, Waste to wealth: chemical recycling and chemical upcycling of waste plastics for a great future, Chem. Europe 14 (2021) 4123 4136. [25] F. Adam, Green Catalysts, Res. Gate (2017) 467 489.

Green Chemistry Approaches to Environmental Sustainability

374

16. Sustainable Development Goals for addressing environmental challenges

[26] Z. Hanxin, M.K. Linda, L. Zofia, The potential of green ammonia production to reduce renewable power curtailment and encourage the energy transition in China, Int. J. Hydrog. Energy 47 (2022) 18935 18954. [27] N. Salmon, B.A. Rene, Green ammonia as a spatial energy vector; a review, Sustainable Energy & Fuels 11 (2021). [28] O. Stephen, Green ammonia could produce climate-friendly ways to store energy and fertilize farms, PNAS 118 (2021). e2119584118. [29] Hemp Farms Australia. Go to Hemp Farms Australia, n.d., from https://hempfarmsaustralia.com.au/heavymetals-trapped-in-our-soils-is-hemp-a-simple-solution/ (retrieved 30.06.22) [30] FAO, Land | Land & Water | Food and Agriculture Organization of the United Nations | Land & Water | Food and Agriculture Organization of the United Nations, 2022. https://www.fao.org/land-water/land/en/. [31] FAO, Water | Land & Water | Food and Agriculture Organization of the United Nations | Land & Water | Food and Agriculture Organization of the United Nations, 2022. https://www.fao.org/land-water/water/en/. [32] Enova Energy Group, Which types of energy source produces the most pollution?, n.d., from https://www. enovaenergygroup.com/which-types-of-energy-source-produces-the-most-pollution/ (retrieved 21.06.22).

Green Chemistry Approaches to Environmental Sustainability

Index Note: Page numbers followed by “f” and “t” refer to figures and tables, respectively.

A Abiotic depletion potential (ADP), 123 124 Abiotic forms, 23 25 Absorption technologies, 188 Acalypha indica, 249 Acanthamoeba castellanii, 156 157 Acenaphthene, 43, 44t Acenaphthylene, 43, 44t 2-acetamido-2-de-oxy D-glucopyranose, 231 232 Acetone, 139 Acetonitrile, 122 Acid catalyst, 17 Acidification potential (AP), 123 Acid rains, 135 137 Acinetobacter radioresistens, 57 Acorus calamus, 56 Acrylonitrile butadiene styrene (ABS), 348 AD. See Anaerobic digestion (AD) Additives, 255 ADP. See Abiotic depletion potential (ADP) Advanced oxidation process (AOPs), 348 AE. See Atom economy (AE) Aerobic mode, 57 AES. See Analytical Eco-scale (AES) AFC. See Alkali fuel cells (AFC) Agaricus bisporus, 345 Agathosma betulina, 251 Agitation, 255 AGREE. See Analytical Greenness Metric Approach and Software (AGREE) Agricultural lands, 35 Agriculture and pest control, 250 AHP. See Analytical Hierarchical Process (AHP) Air pollution, 25 26, 38t effects of, 26 27 possible solutions, 27 28 Air quality index, 26 27 Alcaligenes, 57 58 Alcanivorax borkumensis, 345 α-olefins, 189 190 Algae, 248 249 Alginate, 350 Alkali fuel cells (AFC), 302 303

Alkaloids, 155, 249 Allelochemicals, 4 Alum, 76 77 Alzheimer’s disease, 80 Ambient ionization techniques, 121 Amines, 248 249 Ammonia, 266 267 Ammonium, 69 70 Amphibians, 53 AMVI. See Analytical method volume intensity (AMVI) Anaerobic biodegradation, 324t Anaerobic co-digestion process, 316 319 Anaerobic digestion (AD), 313 314, 316 319 Anaerobic mode, 57 Analytical chemistry, 18 Analytical Eco-scale (AES), 117 Analytical Greenness Metric Approach and Software (AGREE), 118, 124 Analytical Hierarchical Process (AHP), 119 Analytical methods, 110, 115 116 Analytical method volume intensity (AMVI), 118 Anastas, 5 Anderson Schulz Flory (ASF) model, 190 Angiosperms, 250 Animal studies, 51 Anthracene, 43, 44t, 48 Anthropocene, 132, 141 142 Anthropogenic activities, 39, 43 Anthrosphere, 131 132 green chemistry and IE, 135 140 catalysts, 137 chemical/reagents, 140 corrosive compounds, 136 137 feedstock, 138 green chemicals, 137 heavy metals, 136 hydrocarbons, 136 risk pruning, 136 solvents, 139 impact of IE on environment, 134 135 industrial ecosystems design to reduce environmental impact, 140 141 infrastructure and sociosphere of, 132 133

375

376 Antibacterial activity, 151 153 Anticancer drugs, 151 152 Anti-inflammatory activity, 154 155 Antimony (Sb), 123 124 AOPs. See Advanced oxidation process (AOPs) Aqueous medium, 98 99 Arabidopsis thaliana, 55 56 Artificial lighting, 36 37 Artificial photosynthesis, 300 Artificial radioactivity, 166 Ash, 26 Aspergillus, 345 Aspergillus niger, 328 329 Atherosclerosis, 52 Atmosphere, 132 133 Atmospheric chemistry, 3 4 Atmospheric noise, 32 Atom economy (AE), 11, 112t, 221 222 Atom efficiency (AE), 11, 98, 221 222 Atomic Energy Regulatory Board (AERB), 165 Atriplex nummularia, 372 Atropa acuminata, 153t AuNPs. See Gold nanoparticles (AuNPs) Automated unsupervised model, 120 121 Automation techniques, 119 120 Azadirachta indica, 251

B

Bacillus cereus, 58 Bacillus circulans, 57 Bacillus indicus, 243 244 Bacillus megaterium YB3, 57 58 Bacteria, 152, 243 251 Badische Anilin and Sodafabrik (BASF), 185 186 Banana peel ash, 229 Basella alba L., 153t BASILTM, 98 Be´champ reduction, 112, 113f Benz[a]anthracene, 43, 44t Benzaldehyde production, 114 115 Benzene, 115 Berkheya coddii, 371 372 Big Bang theory, 1 Bimetallic catalyst composition, 195 199 Bioaccumulation processes, 219 220 Bioaugmentation, 57 58 Bio-based additives, 350 351 Biocatalysts, 17, 68, 137 Biocatalytic conversion, 17 Biochemical decomposition, 265 Biodegradable nanopolymers, 151 152 Biodiesel, 265, 290 294, 313 314, 325 326 advantages of, 294

Index

disadvantages of, 294 properties of, 293 working of biodiesel fuels, 293 Bioethanol, 265, 313 314, 324 325 Biofuels, 324 329, 368 biodiesel, 325 326 bioethanol, 324 325 biohydrogen, 326 327 biomethane, 328 329 production, 8 9 types of, 364t Biogas power, 296 297 advantages of, 297 biogas plant, 296 297, 296f disadvantages of, 297 Biohydrogen, 313 314, 326 327 Biomass, 139, 224, 359 Biomass-based chemicals, 223 Biomass-derived feedstocks, 230 Biomaterials, 97 Biomedical research, 250 Biomedical waste, 166 167 Biomethane, 313 314, 328 329 Bio oil, 299 300 Bioplastics, 349 350 alginate, 350 polyglycolic acid, 350 polyhydroxyalkanoates, 350 polylactic acid, 349 polytrimethylene terephthalate, 350 Bioproducts, 229 Bioremediation, 57 58, 87, 134, 345, 358, 369 371 advantages of, 370 371 bioaugmentation, 58 biostimulation, 58 Biosorption, 57 Biosphere, 132 133 Biostimulation, 57 58 Biotic forms, 23 25 Bisphenol A polycarbonate (BPA-PC), 348 Blood brain barrier, 150 151, 157 158 Bluegills (Lepomis macrochirus), 54 Bottom up approach, 241, 241f Boudouard reaction, 190 Brassica juncea, 250, 372 Bromines, 170 Bryophytes, 249 250 Bryum argenteum, 249 250 Burkholderia, 57 58 Burkholderia cepacia, 57 58 1,3-butadiene, 110 1,4-butanediol, 100 101

Index

Butyl 3-hydroxybutyrate, 100 1-butyl-3-methylimidazolium hexafluorophosphate, 73

C Cadmium, 71 73 Cadmium-sulphide, 244 247 Caesium, 170, 179t Candida tropicalis, 324 325 Cannabis sativa, 369 370 Carbocation, 193 194 Carbohydrates, 230 Carbon carbon bond, 193 194 Carbon cycle, 225 Carbon dioxide (CO2), 26, 75, 224, 344 Carbon efficiency (CE), 112t Carbon emissions, 132 133 Carbon encapsulated iron carbides/iron nanoparticles (CEICINs), 202 Carbon monoxide, 26 Carbon number, 190, 191f Carbon tetrachloride, 14 Carboxymethyl cellulose, 156 157 Carcinogenicity, 51 Cardiotoxicity, 52 Cardiovascular health, 26 27 Carica papaya, 153t Catalysis, 68, 221 Catalysis hydrogenolysis, 346 Catalysts, 16 17, 137, 225 226, 352 acid catalyst, 17 biocatalysts, 17 phase transfer catalysts, 17 photocatalysts, 17 polymer supported catalyst, 17 for sustainable conversion of CO2 to energy, 194 203 bimetallic catalyst composition, 195 199 catalyst for low Ribblet ratio syngas, 200 203 deactivation behaviour of Fe-Co bimetallic catalyst, 199 200 structural activity relationship, 199 Catalytic cracking, 193 194 Catalytic materials, 226 227 Catalytic system, 225 226 Cattle dung, 262 CCEH. See Centre for Children’s Environmental Health (CCEH) CDM. See Clean development mechanism (CDM) CE. See Carbon efficiency (CE) Cell stack, 301 302 Celluloid, 340 Cellulose, 230

377

Centre for Children’s Environmental Health (CCEH), 51 52 Century plant (Agave Americana), 229 Cetyl-trimethoxysilane, 242 CFCs. See Chlorofluorocarbons (CFCs) Charophyta, 248 249 Chemical-based etching, 241 Chemical industry, 220 221 Chemical/reagents, 140 Chemical synthesis, 221 222 Chemists, 12 14, 110 111 challenges for, 96 97 Chemotherapeutic medicine, 99 Chicken (Gallus gallus), 53 Chiral terpenes, 230 Chitin, 231 232 Chitosan, 231 232 Chlorella vulgaris, 248 249 Chlorofluorocarbons (CFCs), 14, 26 Chloroform, 14 Chlorophyta, 248 249 2-chlorothiphenol, 115 Chromatography, 14 Chronic pulmonary disease, 150 151 Chrysene, 44t Circular economy, 141 Circular pictogram, 117 Cladonia gracilis, 55 Clean development mechanism (CDM), 134 135 Clinoptilolite, 175 176 Clostridium thermoaceticum, 243 244 CMV. See Cytomegalovirus (CMV) Coal, 25 Coal tar, 47 Coal-to-liquid (CTL), 185 186 Cobalt ferrites (CoFe2O4), 199 Co-based catalysts, 195 198 Coenzymes, 155 Collapsing air microbubbles, 87 Combustion, 265 Composting, 320 322, 324t Contamination, 4 5 Copper, 71 73, 239 240 Corrosion products, 168 169 Corrosive compounds, 136 137 Cosmetics and personal care, 250 Cost benefit analysis, 166 Cotton waste, 320 Cowpea mosaic virus (CPMV), 244 247 Curcumin, 156 157 Cutting-edge techniques, 97 Cycloclasticus sp., 57 58 CYP. See Cytochrome P450 (CYP)

378 Cyperus rotundus (CR), 153t Cytochrome P450 (CYP), 50 Cytomegalovirus (CMV), 98 Cytotoxic effects, 150 151 Cytotoxicity, 242

D

DDT. See Dichlorodiphenyltrichloroethane (DDT) Dean-Stark apparatus, 121 122 Deep depth geothermal resource, 278 Deoxyribonucleic acid (DNA), 2 acetylation, 52 methylation, 52 phosphorylation, 52 Desertification, 36 Diabetes, 34, 150 151 Diagnostics, 250 Dichlorodiphenyltrichloroethane (DDT), 17 18 Dichloromethane, 115 Diels Alder reactions, 11, 12f, 73 74, 114 115 Diesel engines, 290 Digestate, 296 297 Digestion process, 265 Dihydrolevoglucosenone, 121 Dimethylisosorbide, 121 Dimethyl sulfoxide (DMSO), 346 Dimethyl sulphate, 140 Dioxygenases hydroxylate, 57 Disease-causing microorganisms, 29 Disposal methods, 173 176 evaporation, 174 glass fixation, 176 ion exchange, 175 176 precipitation and flocculation, 175 storage of liquid and solid wastes, 174 DNA. See Deoxyribonucleic acid (DNA) Double alpha model, 189 190 Drug delivery, 150 151, 250, 252 Drug discovery programme, 111 DuPont reduction, 112, 113f Dynamic membrane filtration, 351 352

E

EAEMPP. See Ethyl acetate extract of Musa paradisica peels (EAEMPP) Earth’s atmosphere, 360 361 Earth’s crust, 26 Ecological paradigm, 115 116 Economic competitiveness, 232 Economy and business, green chemistry, 78 Ecosystem modelling, 141 Ecosystem preservation, 115 116 Ecosystems, 29

Index

Ecotoxicity, 53 E-factor, 109 110, 112t, 124, 221 222 Effective mass yield (EMY), 112t EGO. See Exfoliated graphene oxide (EGO) Eichhornia crassipes, 251 Electric vehicles, 104 Electrochemical cells, 301 Electrodes, 104 Electrolysis, 139t, 299 Electromagnetic radiation, 166 167 ELimination and Choice Expressing Reality (ELECTRE), 119 Emblica officinalis, 153t EMY. See Effective mass yield (EMY) Enantiopure catalysts, 230 Endocrine system disorders, 34 End-of-Life (EoL), 366 Energy-dispersive X-ray (EDX) analysis, 229 Enterobacter cloacae, 243 244 Environment, green chemistry and, 78, 96 97 Environmental acceptability, 9 10 Environmental chemistry, 1 5, 8, 221 components of, 3f contamination and pollution, 4 5 formation of crust and atmosphere, 2 importance of, 3 4 origin and evolution of earth, 2 origin of life and atmosphere, 2 3 Environmental degradation, 39, 111 Environmental impact (EI), 9 10, 118, 221 222 Environmentally friendly transportation, 38 39 Environmental noise, 32 Environmental pollution, 6, 23 switching to sustainable energy requirement for safer environment, 38 39 types of pollution, 25 38 air pollution, 25 26 light pollution, 36 37 noise pollution, 31 32 plastic pollution, 33 34 radioactive pollution, 30 soil pollution, 35 water pollution, 28 Environmental protection, 115 116 Environmental Protection Agency (EPA), 110 Environmental protocols, 117 Environmental remediation, 83 87, 85f, 250 sedimentation technologies, 85 87 bioremediation, 87 collapsing air microbubbles, 87 excavation or dredging, 85 nanoremediation, 87 pump and treat, 85

Index

in situ oxidation, 86 soil vapour extraction, 86 87 solidification and stabilization, 85 surfactant enhanced aquifer remediation, 85 thermal desorption, 85 steps, 84 Environmental sustainability, 23 25 Enzymes, 16 EPA. See Environmental Protection Agency (EPA) Escherichia coli, 243 244 Ethyl acetate, 139 Ethyl acetate extract of Musa paradisica peels (EAEMPP), 136 137 Ethylene glycol, 242, 267 Ethylene oxide, 10, 11f Eutrophication potential (EUP), 123 Evaporation, 174 Excavation or dredging, 85 Exfoliated graphene oxide (EGO), 73 Ex-situ remediation technologies, 84f Extreme cold, 183 Extreme heat, 183

F Face-centred cubic structure, 198 FAIR. See Findable, Accessible, Interoperable, Reusable (FAIR) Father of Green Chemistry, 5 Fe-Co catalyst, 198 Feedstock, 138, 223 224 Fertilizers, 35 Fibre-reinforced plastics (FRPs), 365 366 Ficus benghalensis, 249 Findable, Accessible, Interoperable, Reusable (FAIR), 117 First-generation solar cells, 263 265 Fischer-Tropsch kinetics, 205 210 CO activation in Fischer-Tropsch active sites, 205 208 CO activation in WGS active sites, 209 210 inhibition effect of H2O and CO2, 208 209 Fischer-Tropsch mechanism, 203 205 alkenyl mechanism, 204 alkyl mechanism, 203, 204f CO insertion mechanism, 205 enol mechanism, 204 Fischer Tropsch reactions chain initiation, 189 chain propagation, 189 chain termination and desorption, 189 reactant adsorption, 189 re-adsorption, 189 secondary hydrogenation, 189

379

Fischer Tropsch (FT) synthesis, 185 186 Flavonoids, 155, 249 Floating solar arrays, 268 269 Flocculation, 175 Fluorene, 43, 44t Fluorination, 115 Food and beverage industry, 250 Forensic investigation, 121 Formaldehyde, 266 Fossil fuels, 25, 261 Fourier transform infra-red spectroscopy, 351 352 Freshwater green algae (Selenastrum capricornutum), 57 58 FRPs. See Fibre-reinforced plastics (FRPs) Fucus vesiculosus, 248 249 Fuel cells, 103 104, 301 307 advantages of, 307 disadvantage of, 307 working of, 302 306 Fuel fabrication, 168 Fuel processing plant, 170f Fungal reductive proteins secrete, 247 Fungi and yeast, 247 248 Fusarium oxysporum, 248 Fusarium sp., 248

G

GAC. See Green analytical chemistry (GAC) GAPI. See Green Analytical Procedure Index (GAPI) Gasification, 265, 298, 343 344 Gasohol, 294 295 advantages of, 295 disadvantages of, 295 working of the fuel, 295 Gastrointestinal tract, 54 GDP, 141 GE. See Green economy (GE) Generators, 272 Genotoxicity, 52, 150 151 Geosphere, 131 132 Geothermal electricity, 275 Geothermal energy, 38 39, 274 280, 359 360 advantages of, 279 disadvantages of, 279 280 generation of electricity, 275 industrial applications of underground hot water, 279 techniques of extraction of heat resource, 276 279 types of geothermal resources, 275 276 Geothermal reservoirs, 276 278 binary cycle power station, 277 278, 278f dry steam power plants, 276, 277f enhanced geothermal power station, 278

380

Index

Geothermal reservoirs (Continued) flash steam power station, 276 277, 277f Geothermal resources enhanced geothermal reservoirs, 276 liquid dominated geothermal reservoir, 276 types of, 275 276 vapour dominated geothermal reservoirs, 276 Glass fixation, 176 GlaxoSmithKline solvent selection tool, 118 119 Global warming, 1, 23 25, 135, 141 142 Global warming index (GWI), 123 Global warming potential (GWP), 123 Global warnings, 360 Glucose, 79 Glutathione-S-transferase, 54 Glycerol, 267 GO. See Graphene oxide (GO) Goal modelling, 141 Gold nanoparticles (AuNPs), 153t Governmental organizations, 141 142 Graphene oxide (GO), 73 Green ammonia, 369f Green analytical chemistry (GAC), 110 111, 115 122, 124 125 Green Analytical Procedure Index (GAPI), 118, 124 Green analytical techniques, 116f Green anthrosphere, 132 Green approaches for valorization of OMWW, 316 324 anaerobic digestion, 316 319 biovalorization of OMWW into biofuel, 324 329 biodiesel, 325 326 bioethanol, 324 325 biohydrogen, 326 327 biomethane, 328 329 composting of, 320 322 vermicomposting of, 322 324 Green catalysts, 366 Green chemicals, 137 Green chemistry, 3 5, 6f, 67, 93 95, 109, 135, 220 222, 349, 358 advantages of, 77 78 economy and business, 78 environment, 78 human health, 77 78 alternative renewable energy science, 102 104 photovoltaic solar energy, 102 104 application of, 97 basic principles atom economy, 11 catalysis, 16 17 design for degradation, 17 18 design for energy efficiency, 15 16 designing safer chemicals, 12 14

inherently safer chemistry for accident prevention, 18 less hazardous chemical synthesis, 11 12 real-time analysis for pollution prevention, 18 reducing derivatives, 16 safer solvents and auxiliaries, 14 15 use of renewable feedstocks, 16 waste prevention, 9 11 benefits of, 74 75, 74f bio-based modifications and resources, 100 101 challenges for chemists, 96 97 challenges in research, 104 105 concept of, 69 in day-to-day life, 78 80 environmental problems, 75 76 environmental remediation, 83 87, 85f sedimentation technologies, 85 87 steps, 84 future challenges, 18 19 integrative system consideration, 19 multifunctional catalysts, 19 twelve principles as consistent approach, 18 working on uncertain interaction/ forces of chemical products, 19 greener pharmaceutical industries, 97 99 greener solvents, 99 100 green solution to turn turbid water clear, 80 groundwater and surface water remediation, 82 history and origin of, 6 19, 68, 94 96 impact of, 94 implementation of, 8f need of, 8 9 opportunities for, 75 principles, 223f progression of, 97 remediation of sediments, 83 soil remediation, 80 81 and sustainable chemistry, 75 synthetic chemistry and, 7 8 three primary environmental restoration and cleanup methods, 80 twelve principles of, 10f, 75, 76f, 95 96, 95f, 138t water as solvent for organic reactions, 73 74 water treatments, 76 77 Green Chemistry Twelve Principles, 221 222 Green construction, 38 39 Green dry cleaning, 78 Green economy (GE), 133 policies and paradigm for, 141 GREEN ECONOMY ARCHETYPE, 132 Greener pharmaceutical industries, 97 99 Greener solvents, 99 100 Green fuels, 261 307

Index

biodiesel, 291 294 advantages of, 294 disadvantages of, 294 properties of, 293 working of biodiesel fuels, 293 biogas power, 296 297 advantages of, 297 biogas plant, 296 297, 296f disadvantages of, 297 fuel cells, 301 307 advantages of, 307 disadvantage of, 307 working of, 302 306 gasohol, 294 295 advantages of, 295 disadvantages of, 295 working of the fuel, 295 geothermal power, 274 280 advantages of, 279 disadvantages of, 279 280 generation of electricity, 275 industrial applications of underground hot water, 279 techniques of extraction of heat resource, 276 279 types of geothermal resources, 275 276 hydroelectricity, 289 291 advantages of, 291 disadvantages of, 291 generation of electricity, 290 hydrogen fuel, 297 301 advantages of, 301 disadvantages of, 301 methods of production of hydrogen, 298 300 solar energy, 262 269 advantages of, 268 disadvantages of, 268 heating effect, 263 use of photovoltaics to generate electricity, 263 265 use of solar power, 262 268 tidal energy, 287 289 advantages of, 289 disadvantages of, 289 generation of electricity, 288 289 wave energy, 280 287 advantages of electricity from waves, 285 disadvantages of electricity from waves, 286 generation of electricity, 281 284 wind energy, 269 274 Green house effect, 135 Greenhouse gas (GHG) emissions, 27, 122 123, 135, 223, 261, 280, 361 Green materials, 67

381

Green metrics, 109 110 green analytical chemistry, 115 122 bio-based solvents in synthesis and analysis, 121 122 developed green analytical metrics, 117 120 march towards miniaturization, 120 121 greening of industrial synthesis, 111 115 current industrial processes and metrics, 114 115 waste metrics, 111 113 motivation and goal of, 111 sustainability metrics, 122 124 Green nanotechnology, 239 Green NPs, 242 Green plastics, 34 35 Green process catalysts for sustainable conversion of CO2 to energy, 194 203 bimetallic catalyst composition, 195 199 catalyst for low Ribblet ratio syngas, 200 203 deactivation behaviour of Fe-Co bimetallic catalyst, 199 200 structural activity relationship, 199 reaction mechanics and kinetics, 203 210 Fischer-Tropsch kinetics, 205 210 Fischer-Tropsch mechanism, 203 205 sustainable and renewable energy from CO2 derived renewable biomass, 186 194 composition of syngas, 187 188, 188f energy value for liquid product, 193 194 Plausible reaction networks, 188 190 possibilities of using low Ribblet ratio syngas in Fischer-Tropsch reaction, 191 192 product distribution during process, 190 191 Green synthesis, 239 applications of biologically synthesized nanoparticles, 252 253 biological nanofactories, 243 251 bacteria, 243 251 factors affecting nanoparticle synthesis, 253 256 of nanoparticles, 245t Green synthetic implementations, 97 Green tea polyphenols, 156 157 Grignard reaction, 11 Gross metathesis, 347 Groundwater, 82 Gutta percha, 340 GWI. See Global warming index (GWI) GWP. See Global warming potential (GWP) Gymnosperms, 249 250

H Harnessing wind energy, 269 270 Hazardous industrial waste, 358 359

382

Index

HDMA. See Hexamethylene diamine (HDMA) Heat exchanger technique, 275 276 Heavy metals, 5, 136 Helianthus annuus, 153t Hemicelluloses, 231 232 Hesperidin, 156 157 Heterocyclic polycyclic skeletons, 140 Heterogeneous catalysts, 290, 292 Heterogeneous catalytic system, 226 228 Hexafluoride, 167 168 Hexamethylene diamine (HDMA), 110, 110f HFCEVs. See Hydrogen fuel cell electric vehicles (HFCEVs) High molecular weight (HMW), 43 High performance liquid chromatography (HPLC), 100, 115 116, 118 119 High temperature fuel cells (HTFC), 301 High temperature PEMFCs (HT-PEMFCs), 304 306 HMW. See High molecular weight (HMW) HOC. See Hydrophobic organic contaminants (HOC) Homogeneous catalysts, 292 HPLC. See High performance liquid chromatography (HPLC) HTFC. See High temperature fuel cells (HTFC) Human cell line, 251 Human health, green chemistry and, 77 78 Humanity, 141 142 Hydrazine, 242, 266 267 Hydrocarbons, 5, 26, 136 Hydrochloric acid, 94 Hydrocracking, 193 194, 193f Hydroelectricity, 289 291, 359 360 advantages of, 291 disadvantages of, 291 generation of electricity, 290 Hydrogen fuel, 297 301 advantages of, 301 disadvantages of, 301 methods of production of hydrogen, 298 300 Hydrogen fuel cell electric vehicles (HFCEVs), 364 Hydrogenolysis, 346 Hydrogen peroxide (H2O2), 98 99, 267, 316 319 Hydrolase, 345 Hydrophobic cell membrane, 94 Hydrophobic organic contaminants (HOC), 49 Hydrosphere, 131 133

I

IAEA. See International Atomic Energy Agency (IAEA) IBD. See Intestinal bowel disease (IBD) Ideonella sakaiensis, 345 IE. See Industrial ecology (IE) ILs. See Ionic liquids (ILs)

Imidazolium, 69 70 Indian Standard Institute (ISI), 28 Industrial chemistry, 9 Industrial ecology (IE), 133 Industrial symbiosis (IS), 134 135 Industry noise, 32 Inorganic solar cells, 263 265 In situ oxidation, 86 In situ technologies, 83f Integrative system consideration, 19 International Atomic Energy Agency (IAEA), 31 International Commission on Radiological Protection (ICRP), 31, 179 International Energy Agency, 275 International Renewable Energy Agency (IRENA), 268 269 Intestinal bowel disease (IBD), 154 155 Intracellular parasites, 244 247 Iodines, 170 Ion exchange, 175 176 Ion-exchange chromatographic, 229 Ionic liquids (ILs), 14, 68 73, 69f, 121, 221 application of, 72f characteristics of, 71 73 industrials uses of, 72f Iron-oxide, 244 247 IS. See Industrial symbiosis (IS) ISI. See Indian Standard Institute (ISI) Isoflavones, 122 Isomerization reaction, 194

J

Jatropha curcas (JC), 153t

K Keratinase, 367 Klebsiella pneumoniae, 243 244 Knoevenagel reaction, 229 Krypton, 170 Kyoto Protocol, 27 28

L Lab-in-a syringe, 116 Lab-on-a-chip, 116 Lab-on-a-valve, 116 Lactase, 345 Landfills, 344 Larynx, 51 Laser-based ablation, 241 Less hazardous chemical synthesis, 11 12 Letermovir, 98 Levulinic acid, 102 Life cycle assessment, 112 113

Index

Light emitting diodes, 115 Light pollution, 36 37, 38t effects of, 37 possible solutions, 37 38 Lignin, 230 Lignocellulose feedstock, 121 122 Limonene, 121 122 Lipid-soluble organic solvents, 136 Lipitor, 103 Liposomal vesicles, 156 157 Liquid biopsy, 150 151 Liquid wastes, 174 Lithium, 365 Lithography, 241 Lithosphere, 132 133 Living nanofactories, 240 241 cost savings, 241 customization, 241 increased efficiency, 240 reduced environmental impact, 240 LMW. See Low molecular weight (LMW) Lonicera japonica, 242 243 Low molecular weight (LMW), 43 Low temperature fuel cells (LTFC), 301 LTFC. See Low temperature fuel cells (LTFC) Lurgi gasifiers, 188 Lysozyme, 156 157

M

Mallard (Anas platyrhynchos), 53 Mangifera indica, 153t Marasmius oreades, 345 Marine microalgae, 248 249 Marine organisms, 223 224 Mass intensity (MI), 112t Mass productivity (MP), 112t Mass spectrometry (MS), 121 MAUT. See Multi Attribute Utility Theory (MAUT) MAVT. See Multi Attribute Value Theory (MAVT) “Maximum credible accident” effects, 169 Maximum permissible concentration (MPC), 181 MCDA. See Multicriterial decision analysis (MCDA) MCFC. See Molten carbonate fuel cells (MCFC) MDCB. See Methods and Data Comparability Board (MDCB) Medicago sativa, 56 Melt process, 12 Membrane bioreactor, 351 352 Metal-air batteries, 365 Metal NPs, 150 151 Methane (CH4), 344, 360 361 Methanol, 122 Methanol carbonylation, 114 115

383

Methods and Data Comparability Board (MDCB), 117 Methylene chloride, 12, 14 Methyl isobutyl ketone, 94 2-Methyloxolane (2-MeOx), 122 MeyGen project, 287 Microalgae, 351 352 Microbial electrolysis, 300 Microgas chromatography (μ-GC), 120 121 Microorganisms, 57, 223 224, 322 323, 358 Microplastics, 33 34, 351 352 Microscopic imaging techniques, 119 120 Microscopy, 119 120 Microtubular SOFC (MT-SOFC), 306 Microwaves, 139t Molten carbonate fuel cells (MCFC), 303 Momordica charantia, 153t Monometallic catalyst, 195 198 Monooxygenase, 57 Montreal Protocol, 27 28 Moraxella, 345 Moringa oleifera, 153t MPE. See Multiphase extraction (MPE) MS. See Mass spectrometry (MS) Multi Attribute Utility Theory (MAUT), 119 Multi Attribute Value Theory (MAVT), 119 Multicriterial decision analysis (MCDA), 119 120 Multifunctional catalysts, 19 Multiphase extraction (MPE), 86 87 Multiwalled carbon nanotubes (MWCNTs), 347 Mycobacterium, 57 58 Mycoremediation, 36

N N-acetylation, 231 232 Naegleria fowleri, 156 157 Nanobiotechnology, 239 Nanocarriers, 156 157 Nanoformulation, 152 Nanomaterials, 140 141, 150 151, 157 158, 239 Nanoparticles (NPs), 149, 239 240, 244 247. See also Nanoparticles (NPs) drug encapsulation in, 154 155 green syntheses of, 151 152 toxicity of, 150 151 Nanopharmacology, 150 151 Nanoplastics, 34 Nanoremediation, 87 Nanostructures, 156 157 Nanotechnology, 149 151, 157 158 Nanotoxicology, 157 158 Naphthalene, 43, 44t, 57 58 National Interim Primary Drinking Water Standards (NIPDWS), 28

384 National Registry of Radiation Workers (NRRW), 171 172 National Renewable Energies Laboratory, 103 Natural feedstock, 225 226 Natural gas, 25, 187 188 Natural plastics, 338 Natural products, 230 232 N-butylepyrrolidinone, 121 NEMI, 117, 124 Neurospora, 248 Neurospora crassa, 248 Neurotoxicity, 150 151 Neutral tube defects (NTDs), 51 52 Next-generation fuels, 364 Next-generation green ammonia, 368 369 Next-generation green catalysts, 366 368 Next-generation sustainable batteries, 364 365 Next-generation waste-to-recyclates, 365 366 N-formylmorpholine, 121 Nicotinamide adenine dinucleotide (NADH), 247 NIPDWS. See National Interim Primary Drinking Water Standards (NIPDWS) Nitric acid, 35 Nitrogen, 168 169 Nitrous oxides (NxO), 131 132, 360 361 NMR. See Nuclear magnetic resonance (NMR) Nocardia, 345 Noise pollution, 31 32, 38t atmospheric noise, 32 effect of, 32 33 environmental noise, 32 occupational noise, 32 possible solutions, 33 Noncorrodible cladding, 168 Nonmetallic NPs, 150 151 Nonpathogenic fungi, 248 Nonpoint source, 23, 24f NTDs. See Neutral tube defects (NTDs) n-type semiconductor, 263 265 Nuclear fission, 165, 167 168 Nuclear magnetic resonance (NMR), 121 Nuclear power generation, 165 Nuclear power plants, 168 Nuclear waste, 166 Nutraceuticals, 149, 155 157 Nylon-6, 346

O Obesity, 34 Occupational noise, 32 Odour emissions, 321 322 ODP. See Ozone depletion potential (ODP) Oesophagus, 51

Index

Off-shore wind farms, 271 Oil spills, 47 48 Oligomerizing ethylene, 194 Olive husk, 316 Olive mill solid wastes (OMSW), 321 Olive mill wastewater (OMWW), 313 anaerobic digestion, 316 319 composting of, 320 322 production and characteristics, 314 316 vermicomposting of, 322 324 Olive oil (Olea Europaea L.), 314 316 Olive oil solid residue (OOSR), 321 Olive pomace, 316 On-shore wind farms, 271 Organic farming, 36 Organic reactions, 14 in aqueous media, 15f Organic solvents, 14, 120 121 Organic synthesis, 116 Organometals, 5 Organometaltrihalides, 102 Oropharynx, 51 OryxGTL (Qatar Petroleum- Sasol), 185 186 Oscillating-wave-by-column (OCW) devices, 281 282 Oxidation process, 221 Oxidative stress, 150 151 Oxidoreductase, 345 Oxygenase, 345 Oxygenates forming reaction, 190 Ozone (O3), 2 Ozone depletion potential (ODP), 123, 135

P Paclitaxel, 99 PAFC. See Phosphoric acid fuel cell (PAFC) PAHs. See Polycyclic aromatic hydrocarbons (PAHs) Papaver somniferum L., 153t Parthenium hysterophorus, 249 Partition coefficient, 71 73 Passiflora caerulea L., 153t Passiflora foetida, 249 Pasteurella, 57 58 Pathogenesis related protein (PR1), 56 Pathogens, 29 PCBs. See Polychlorinated biphenyls (PCBs) PearlGTL (Qatar Petroleum- Shell), 185 186 Pelargonium graveolens, 153t PEMFC. See Proton exchange membrane fuel cell (PEMFC) Penicillium, 345 Perchloroethylene, 78 Perovskite materials, 263 265 Perovskite solar devices, 102

Index

Peroxidase, 345 Pesticides, 5, 35 PET. See Polyethylene terephthalate (PET) Pfizer’s research scientists, 98 99 pH, 255 Phaeocystis antarctica, 243 244 Pharmaceutical and agricultural chemical industries, 232 Pharmaceutical industry, 67 68, 98 Pharmaceuticals antibacterial activity, 152 153 anticancer role, 155 anti-inflammatory activity, 154 155 antiviral role against COVID-19, 155 plant-derived nanoparticles in, 152 plant-derived nanostructures in nutraceuticals formulation, 155 157 Phase transfer catalysts (PTCs), 17 Phenanthrene, 43, 44t, 56 57 Phosgene, 12 Phospholipids, 122 Phosphonium, 69 70 Phosphoric acid fuel cell (PAFC), 303 Photocatalysts, 17, 114 115, 139t Photocatalytic cycloaddition reaction, 115 Photocatalytic reactions, 68 Photochemical ozone creation potential (POCP), 123 Photochemical process, 2 Photochemical reactions, 139t Photoreforming, 347 Photosensitive compounds, 55 Photosynthesis process, 2, 37 Photosynthetic activity, 56 57 Photovoltaic method, 79 Photovoltaic solar energy, 102 104 fuel cells, 103 104 quantum dots, 103 sustainable energy storage, 104 Phytoremediation, 36, 57, 369 371 Phytosomes, 250 251 Phytotech, 371 372 Phytotoxicity, 242 Pigments, 248 249 Pink salmon (Oncorhynchus gorbuscha), 52 Pinus radiata, 250 Plant-based NPs, 151 152, 250 251 Plant-derived nanomedicine, 155 Plant-derived nanoparticles, 152, 153t Plant-derived phytochemicals, 151 152 Plant growth, 56 Plant life, 37 Plants metabolites, 152

385

in synthesis of NPs, 249 251 Plastic consumption, 337 338 Plastic pollution, 33 34, 38t effects of, 34 possible solutions, 34 35 Plastic waste, 34 35 Plastics classifications, 338 339 natural plastics, 338 semisynthetic plastics, 339 synthetic plastics, 339 complexity associated with plastic waste, 341 342 harmful effects of plastic waste, 341 history of, 340 341 management strategies to control plastic waste pollution, 342 352 bio-based additives, 350 351 bioplastics, 349 350 bioremediation, 345 catalysis hydrogenolysis, 346 landfills, 344 microplastics, 351 352 polymerization, 348 349 recycling, 343 344 upcycling to alkane, 347 upcycling to carbon materials, 347 upcycling to chemical monomers, 346 upcycling to fuels, 346 upcycling to hydrogen, 347 Plastisphere, 337 338 Platform modelling, 141 Platinum (Pt), 242 243 Plausible reaction networks, 188 190 Pleurotus sajor-caju, 324 325 Plumbago zeylanica, 249 Plutonium, 179t PMI. See Process mass intensity (PMI) POCP. See Photochemical ozone creation potential (POCP) Point source, 23, 24f Poisonous gas emissions, 23 25 Polaromonas, 57 58 Pollutant, 23 Pollution, 4 5 Pollution Prevention Act of 1990, 68 Poly (lactic-co-glycolic acid)_, 151 152 Polyaryl ether sulfone (PSUs), 348 Polycarbonate, 12, 13f Polychlorinated biphenyls (PCBs), 136 Polycyclic aromatic hydrocarbons (PAHs), 43, 44t, 351 352 absorption of, 55 accumulation of, 56

386 Polycyclic aromatic hydrocarbons (PAHs) (Continued) bacterial degradation of, 48 49 bioremediation of, 57 58 bioaugmentation, 58 biostimulation, 58 effect on photosynthetic activity, 56 57 effect on plant growth, 56 in environment, 49 50 microbial degradation of, 49 natural sources of, 47 in plants, 55 56 reactive metabolites of, 51 toxicity, 50 57 on birds, amphibians and aquatic animals, 53 54 in environmental matrices, 50 51 on humans, 51 53 Polycystic ovarian syndrome, 48 Polyethylene (PE), 340 Polyethylene terephthalate (PET), 345 Polyglycolic acid, 151 152, 350 Polyhydroxyalkanoates (PHAs), 350 Polylactic acid (PLA), 347, 349 Polylactide, 151 152 Polymer depolymerization methods, 348 Polymeric nanoparticles, 73 Polymerization, 348 349 liquid and gaseous hydrocarbon fuel production, 348 349 polymer depolymerization methods, 348 Polymer supported catalyst, 17 Polypeptides, 248 249 Polyphenol, 155 Polypropylene (PP), 341 342, 346 Polypropylene carbonate, 122 Polysaccharides, 79, 248 249 Polytrimethylene terephthalate, 350 Polyurethane (PU), 345 Polyvinyl chloride (PVC), 348 Pomegranate peel ash, 229 Powdered tamarind seed kernels, 80 PR1. See Pathogenesis related protein (PR1) Precipitation, 175 Precursor materials, 255 Preference Ranking Organization Method for Enrichment Evaluations (PROMETHEE), 119 Processing methods, 255 Process mass intensity (PMI), 112t Production well, 276 Prokaryotes, 243 244 Prokaryotic cells, 247 Propylene carbonate, 121 Proton exchange membrane fuel cell (PEMFC), 304 306

Index

Prozac, 103 Pseudomonas, 57 58 Pseudomonas fluorescens, 57 58 Pseudomonas proteolytica, 243 244 Pseudomonas putida, 243 244, 371 PTCs. See Phase transfer catalysts (PTCs) Pteridophytes, 249 250 p-type semiconductor, 263 265 Pump and treat, 85 Pyrene, 44t, 56 57 Pyridinium, 69 70 Pyrogenic PAHs, 47 48 Pyrolysis, 265, 300, 343 Pyrrolidinium, 69 70

Q Quality of life, 9 Quantum dots, 103 Quantum dot solar cells, 263 265

R Radioactive elements, 30 31 Radioactive iodine, 172 Radioactive pollution, 30, 38t effects of, 30 31 health impact of, 171 172 possible solutions, 31 Radioactive radiation, 165 166 Radioactive waste management, 165, 169, 179t Radioactive waste minimization disposal guidelines, 172 173 delay and decay, 173 dispersion and dilution, 173 isolation and concentration, 172 disposal methods, 173 176 evaporation, 174 glass fixation, 176 ion exchange, 175 176 precipitation and flocculation, 175 storage of liquid and solid wastes, 174 fracturing of rocks, 176 179 conditioning, 178 179 salt mines, 177 solids, 177 178 protection and radiation control, 179 183 defence against fire, 182 defence against insects and rodents, 182 limiting workplace radiation exposure, 181 maximum allowable dose for radiation protection, 179 protection from high temperatures, 183 radiation-based regulation, 180 181 radiation protection precautions, 179 180

Index

security, 181 182 sources of nuclear wastes, 167 172 fuel fabrication, 168 mining and milling of uranium, 167 processing of uranium oxides, 167 168 reactor wastes, 168 169 spent fuel processing, 169 172 Radiography, 30 Radioisotopes, 165 Radionuclides, 183 Ralstonia, 57 58 Raman spectroscopy, 351 352 Rana temporaria, 53 Raw materials, 9, 109, 132 133 Reaction mass efficiency (RME), 112t Reactions in aqueous phase, 15 Reaction time, 255 Reactive gases (RG), 124 Reactive oxygen species (ROS), 55, 150 151 Reactor wastes, 168 169 Real-time analysis for pollution prevention, 18 Recrystallization, 14 Recycling, 343 344 incineration, 344 primary recycling, 343 secondary recycling, 343 tertiary recycling, 343 344 Red mud, 140 141 Remediation, 5, 80 Renewable energy sources, 221, 223 Renewable feedstocks advantages of renewability factors in organic synthesis, 232 as catalytic system, 225 226 different renewable resources used in organic synthetic chemistry, 226 232 bioproducts, 229 heterogeneous catalytic system, 226 228 natural products, 230 232 future challenges and outlooks, 232 green chemistry, 221 222 and renewable energy, 223 224 requirements of renewable and sustainable feedstocks, 224 225 Reproductive impairment, 34 Reptile species, 54 Reusable water bottle, 80 Rhodobacter sphaeroides, 326 327 Rhodococcus, 57 58 Rhodopseudomonas capsulata, 243 244 Rhodopseudomonas palustri sp., 326 327 Ribblet ratio, 188 Rice straw ash extract, 229

387

Risk pruning, 136 RME. See Reaction mass efficiency (RME) ROS. See Reactive oxygen species (ROS) Ruthenium, 170

S

Saccharomyces cerevisiae MAK-1, 324 325 Safe dumping, 134 Salt mines, 177 Sargassum wightii, 248 249 Scadoxus multiflorus, 251 Scenedesmus obliquus lipid, 229 SCFs. See Supercritical fluids (SCFs) SDGs. See Sustainable Development Goals (SDGs) Second-generation solar cells, 263 265 Sediments, 83 Segetis, 102 Semiquantitative metric, 118 Semisynthetic plastics, 339 SFP. See Smog formation potential (SFP) Shallow depth geothermal resource, 278 Sheldon’s environmental (E) factor, 225 Silicate glasses, 136 137 Silicon-dioxide, 244 247 Silver, 239 240 Simple Additive Weighting, 119 Small wind turbines (SWT), 269 270 Smog formation potential (SFP), 124 Sociosphere, 133 Sodium borohydride (NaBH4), 242 Sodium citrate, 242 Sodium-dodecyl-sulfate, 242 Soil chemistry, 3 4 Soil pollution, 35, 38t effects of, 35 36 possible solutions, 36 Soil remediation, 80 81 Soil vapour extraction (SVE), 86 87 Solar array, 79, 263 265 Solar cells, 70 71, 97, 263 265, 264f Solar energy, 38 39, 262 269, 359 360 advantages of, 268 disadvantages of, 268 heating effect, 263 use of photovoltaics to generate electricity, 263 265 use of solar power, 262 268 Solar panels, 263 265 Solidification and stabilization, 85 Solid oxide fuel cells (SOFC), 266 267, 306 Solid wastes, 174 Solvents, 139 Sonochemistry, 139t Sorona polymer, 100

388 Spent fuel processing, 169 172 health impact of radioactive pollution, 171 172 Sphingomonas, 57 58 Sphingomonas paucimobilis, 57 58 Sputtering, 241 Static noise, 32 Steam methane reforming, 268 Steam reforming, 298 Stenotrophomonas maltophilia, 57 58 Steroids, 155 Stoichiometric reagents, 16 Stoichiometric transformations, 230 Streptomyces, 57 58, 345 Strontium, 179t Structural activity relationship, 199 Substrate concentration, 255 Sugar cane bagasse, 320 Sulphonium, 69 70 Sulphur dioxide, 26 27, 131 132 Sulphuric acid, 35, 131 132 Supercritical carbon dioxide, 221 Supercritical CO2, 14 Supercritical fluids (SCFs), 120 121 Supercritical water, 15 Surface charge, 255 Surface modifications, 255 Surface reconstruction, 200 Surface water remediation, 82 Surfactant enhanced aquifer remediation, 85 Surfactant leaching, 36 Sustainability, 261 Sustainability metrics, 122 124 Sustainable and renewable energy from CO2 derived renewable biomass, 186 194 composition of syngas, 187 188, 188f energy value for liquid product, 193 194 Plausible reaction networks, 188 190 possibilities of using low Ribblet ratio syngas in Fischer-Tropsch reaction, 191 192 product distribution during process, 190 191 Sustainable building, 38 39 Sustainable chemistry, 5, 67 68, 75 Sustainable development, 8 9, 357 358 Sustainable Development Goals (SDGs), 75, 357 358 application of biotechnology in, 371 bioremediation, 369 371 case studies, 371 372 ensuring access to sustainable energy, 359 369 availability of cleaner fuel choices, 363 building next-generation energy sources, 364 369 building sustainable chemistry to combat climate change, 360 361 building sustainable ecosystem in water, 363

Index

building sustainable ecosystem on land, 361 363 phytoremediation, 369 371 progress reports from 2016 to 2020, 362t sustainable management of clean water and sanitation, 358 359 Sustainable energy, 38 39 Sustainable energy storage, 104 Sustainable environment, 219 220 Sustainable Land Management (SLM), 361 363 SVE. See Soil vapour extraction (SVE) Synthetic chemistry, 7 8, 109 112, 121, 221 Synthetic NPs, 149 Synthetic organic chemistry, 111 Synthetic plastics, 339

T

Tagetes patula, 56 Tamarind seed kernel powder, 79 Tannins, 155 Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), 119 Temperature, 255 Tenotrophomonas, 57 58 Teratogenicity, 51 52 Terpenes, 231 232 Terpenoids, 249 Terrestrial environment, 34 Tetrafluoride, 167 168 Tetraphenylmethane, 73 Thamnidium elegans, 325 326 Therapeutic applications, 152 Thermal analysis, 119 120 Thermal cracking, 193 194 Thermal desorption, 85 Thermal evaporation, 241 3Rs of plastic management, 34 35 Thyroid cancer, 172 Thyroid dysfunction, 34 Tidal energy, 287 289 advantages of, 289 disadvantages of, 289 generation of electricity, 288 289 Tobacco mosaic virus (TMV), 242 243 Tolerance dose, 179 Top down approach, 241, 241f Top down techniques, 241 Topography, 27 28 TOPSIS. See Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) Toxicity, 50 57 in environmental matrices, 50 51 on humans, 51 53 carcinogenicity, 51

Index

cardiotoxicity, 52 ecotoxicity, 53 genotoxicity, 52 teratogenicity, 51 52 transgenerational effects, 52 Toxicological chemistry, 3 4 Toxics Release Inventory (TRI), 94 TPOMW. See Two-phase olive-mill waste (TPOMW) Transgenerational effects, 52 Transportation, 96 97 Transretinoic acid, 156 157 Tree-Ring Data Bank, 360 TRI. See Toxics Release Inventory (TRI) Trichloroethylene, 94 Trichoderma, 248 Tritium, 169 170 Trost’s Atom Economy notion, 225 Tuberculosis (TB), 372 Twelve principles, 75, 76f as consistent approach, 18 Two-phase olive-mill waste (TPOMW), 314 316

U United States Environmental Protection Agency (USEPA), 43 Up-flow anaerobic sludge blanket (UASB) reactors, 316 319 Uranium, 165 166, 179t mining and milling of, 167 Uranium oxides, 167 168 USEPA. See United States Environmental Protection Agency (USEPA)

V Vanillin, 230 Vapour liquid equilibrium, 189 190 V-complex catalyst, 16 Vermicomposting, 322 324, 324t Vermiculite, 175 176 Versatile bleaching agents, 78 Vertebra, 132 133 Vertical axis wind turbine (VAWT), 269 270 Verticillium sp., 248 Vibrational spectroscopy, 119 120 Viruses, 244 247 Virus-like particles (VLPs), 155 Vitamin A, 156 157 Vitex trifolia, 251 VLPs. See Virus-like particles (VLPs) VOCs. See Volatile organic compounds (VOCs) Volatile organic compounds (VOCs), 16, 69, 123, 136 Vulcanite, 340

W Waste, 109 110 Waste cooking oil (WCO), 292 293 Waste disposal problem, 169 Waste management, 166 167 Waste prevention, 9 11 Waste treatment, 6 Water consumption, 358 359 Water gas shift (WGS) reaction, 189 190 Water hyacinth (Eichhornia crassipes), 229 Water pollution, 28, 38t effect of, 29 possible solutions, 29 30 Water treatments, 76 77 Wave energy, 280 287 advantages of electricity from waves, 285 disadvantages of electricity from waves, 286 generation of electricity, 281 284 Wave energy converters (WEC), 281 282 classification of, 282 attenuators, 282 point absorbers, 282 terminators, 282 near shore devices, 281 off-shore devices, 281 282 on-shore devices, 281 working principle, 282 floating devices, 282 oscillating wave surge converters, 282 overtopping devices, 283 pressure differentials, 284 surface attenuators, 282 WCO. See Waste cooking oil (WCO) Wet-chemical methodologies, 242 Wheat straw, 320 WHO. See World Health Organization (WHO) Wind energy, 38 39, 269 274, 359 360 Wind farms, 271 272 off-shore wind farms, 271 on-shore wind farms, 271, 271f Wind mills, 269 270 advantages of, 272 construction of, 272, 273f disadvantages of, 273 274 generation of electricity, 269 272 Wind power, 272 Wind turbines, 269 270, 270f, 365 366 World Health Organization (WHO), 28

X Xenon, 170

389

390 Y

Yarrowia lipolytica, 325 326 Yeast, 247 248 Yeast strain (Lipomyces starkeyi), 325 326

Z

Zanthoxylum armatum, 153t Zero waste, 109 Zinc, 71 73, 239 240

Index

Zinc oxide (ZnO), 150 151 Zinc-sulphide, 244 247 Zingiber officinale, 249 Zirconium, 168 Zirconium oxide, 239 240 Zocor, 99 Zoloft, 103 Zygomycetes fungi, 325 326 Zygorhynchus moelleri, 325 326