Advanced Materials from Recycled Waste 0323856047, 9780323856041

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ADVANCED MATERIALS FROM RECYCLED WASTE

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ADVANCED MATERIALS FROM RECYCLED WASTE Edited by

SARIKA VERMA Industrial Waste Utilization, Nano and Biomaterials, CSIR-Advanced Materials and Processes Research Institute (AMPRI), Bhopal, Madhya Pradesh, India Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India

RAJU KHAN Industrial Waste Utilization, Nano and Biomaterials, CSIR-Advanced Materials and Processes Research Institute (AMPRI), Bhopal, Madhya Pradesh, India

MEDHA MILI Green Engineered Materials and Additive Manufacturing, CSIR-Advanced Materials and Processes Research Institute (AMPRI), Bhopal, Madhya Pradesh, India Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India

S.A.R. HASHMI Green Engineered Materials and Additive Manufacturing, CSIR-Advanced Materials and Processes Research Institute (AMPRI), Bhopal, Madhya Pradesh, India Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India

AVANISH KUMAR SRIVASTAVA CSIR-Advanced Materials and Processes Research Institute (AMPRI), Bhopal, Madhya Pradesh, India

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 © 2023 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: 978-0-323-85604-1 For information on all Elsevier publications visit our website at https://www.elsevier.com/books-and-journals

Publisher: Matthew Deans Acquisitions Editor: Kayla Dos Santos Editorial Project Manager: Isabella C. Silva Production Project Manager: Prem Kumar Kaliamoorthi Cover Designer: Greg Harris Typeset by STRAIVE, India

Contents Contributors Preface Acknowledgments

xi xv xvii

1. Industrial solid waste: An overview N.B. Singh and R.G. Chaudhary 1.1 Introduction 1.2 Classification of ISW 1.3 Wastes from different industries: Generation, properties and uses 1.4 Conclusions and future prospects References

1 2 4 21 22

2. Exploring brine sludge and fly ash waste for making nontoxic radiation shielding materials Sarika Verma, Sriparna Paul, Harsh Bajpai, Mohd. Akram Khan, and Medha Mili 2.1 2.2 2.3 2.4

Introduction Brine sludge as radiation shielding materials Fly ash as radiation shielding materials Applications of brine sludge and fly ash as nontoxic radiation shielding materials 2.5 Conclusion 2.6 Future perspectives References

27 32 37 37 41 41 42

3. Use of red mud as advanced soil stabilization material Suchita Rai, Sneha Bahadure, M.J. Chaddha, and A. Agnihotri 3.1 Introduction 3.2 Chemical properties of red mud 3.3 Physical properties of soil and red mud 3.4 Red mud as a soil stabilizer 3.5 Discussion 3.6 Conclusion References

v

45 46 47 47 49 50 54

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Contents

4. Conversion of agricultural crop waste into valuable chemicals Vrushali H. Jadhav, Chetana R. Patil, and Sanjay P. Kamble 4.1 Introduction 4.2 Value-added chemicals from lignocellulosic biomass 4.3 Conclusions and future prospect Acknowledgments References

57 61 81 81 81

5. Membrane-based treatment of wastewater generated in pharmaceutical and textile industries for a sustainable environment Monti Gogoi, Rajiv Goswami, and Swapnali Hazarika 5.1 A brief overview on pharmaceutical and textile waste 5.2 Wastewater: A source of environmental hazards 5.3 Effective performance of membrane on wastewater 5.4 Effect of nanocomposite membrane on wastewater treatment process 5.5 Conclusion References

87 91 92 99 105 106

6. Efficient and nutritive value addition of waste from food processing industries Alimpia Borah, Rajiv Goswami, and Swapnali Hazarika 6.1 A brief overview on food waste 6.2 Types of food waste 6.3 Process for recovery of waste products 6.4 Extraction of food waste 6.5 Recovery of bioactive compounds from waste 6.6 Potential applicability of food waste 6.7 Conclusion References

111 115 118 119 125 127 128 129

7. Waste incorporation in glass: A potential alternative and safe utilization Ashis Kumar Mandal, Sourja Ghosh, Barun Haldar, Sourav Nag, and Sitendu Mandal 7.1 Introduction 7.2 Material and method 7.3 Result and discussion 7.4 Conclusion Acknowledgment References

133 142 145 150 151 151

Contents

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8. Agricultural waste: Sustainable valuable products Pranjal Kalita, Sanjay Basumatary, Biswajit Nath, and Manasi Buzar Baruah 8.1 Introduction 8.2 Current scenario of agricultural waste 8.3 Agricultural wastes toward biorefinery process 8.4 Agricultural waste toward platform chemicals 8.5 Agricultural waste toward pharmaceutical chemicals 8.6 Other value-added products 8.7 Conclusions References

155 157 160 166 169 170 171 172

9. Use of industrial waste for value-added products Dilip D. Sarode 9.1 Introduction 9.2 Different industrial waste and their uses 9.3 Concluding remarks Acknowledgment References

179 180 195 196 196

10. Conversion of agriculture, forest, and garden waste for alternate energy source: Bio-oil and biochar production from surplus agricultural waste Dilip D. Sarode, Rohan S. Oak, and Jyeshtharaj B. Joshi 10.1 Introduction 10.2 Literature review 10.3 Materials and method 10.4 Results and discussion 10.5 Economic benefits of combined production of biochar and bio-oil 10.6 Conclusions and suggestion for future work Acknowledgment References

199 201 207 209 214 217 218 219

11. Agricultural waste: An exploration of the innovative possibilities in the pursuit of long-term sustainability Mohd Aseel Rizwan, Mamta Bhagat, Surinder Singh, S. Arisutha, S. Suresh, Sarika Verma, and Sushil Kumar Kansal 11.1 Introduction 11.2 Categorization and sources of agricultural waste 11.3 Effect of agricultural residue on an environment and human health 11.4 Value-added products from agricultural wastes 11.5 Conclusions and future scope References

221 223 227 228 234 235

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Contents

12. Utilization of value-added products from fly ash: An industrial waste Mamta Bhagat, Surinder Singh, S. Suresh, S. Arisutha, Sarika Verma, and Sushil Kumar Kansal 12.1 Introduction 12.2 FA properties 12.3 Fly ash (FA) applications in different fields 12.4 Conclusions and recommendations References

239 242 244 250 251

13. Advanced geopolymer: Utilizing industrial waste to material to achieve zero waste Akm Rahman and Sudhir Amritphale 13.1 13.2 13.3 13.4

Introduction Basic principles of solid waste management Industrial wastes utilization in geopolymer technology Municipal waste encapsulation and integration into geopolymer technology 13.5 Advanced applications of waste driven geopolymer 13.6 Summary 13.7 Diversity statement 13.8 Conclusion and future perspectives References

255 258 262 266 268 269 269 270 270

14. Utilization of waste glass fiber in polymer composites U.K. Dwivedi, Sarika Verma, Ravi Kant Choubey, and S.A.R. Hashmi 14.1 Introduction 14.2 About waste glass fiber (WGF) 14.3 Some studies on the separation of fibers from waste FRP 14.4 Development of suitable polymer composite 14.5 Wear behavior of waste glass fiber (WGF)-polyester composites 14.6 Possible applications of waste glass fiber 14.7 Conclusions References

273 276 276 281 286 292 292 293

15. Muga silk: Sustainable materials for emerging technology Manasi Buzar Baruah and Pranjal Kalita 15.1 15.2 15.3 15.4 15.5

Introduction Origin of silk Types of silk Antiquity of Muga silk in Assam Distribution of Muga silk

295 296 296 297 298

Contents

15.6 Present status of Muga silk 15.7 Cultivation of Muga silk 15.8 Compositions of Muga silk 15.9 Fibroin (central structure protein) 15.10 Sericin (glue protein) 15.11 Properties of Muga silk 15.12 Uses and applications 15.13 Dietary application 15.14 Biomedical applications 15.15 Tissue engineering 15.16 Pharmaceutical application 15.17 Cosmetic application 15.18 Textile application 15.19 Art craft application 15.20 Construction applications 15.21 Application as biodiesel 15.22 Conclusion Acknowledgment References

ix 300 301 303 304 304 305 307 309 310 310 311 311 312 313 314 314 314 315 315

16. Plastic recycling: Challenges, opportunities, and future aspects Nishant Markandeya, Amol N. Joshi, Nayaku N. Chavan, and Sanjay P. Kamble 16.1 Introduction 16.2 Steps involved in plastic recycling and advantages of recycling 16.3 Chemical recycling methods for various polymers 16.4 Applications and properties of recycled polymers 16.5 Plastic recycling and CO2 emissions 16.6 Conclusions and future aspects Acknowledgments References

Index

317 319 320 342 347 350 351 351

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Contributors A. Agnihotri Jawaharlal Nehru Aluminium Research Development and Design Centre (JNARDDC), Nagpur, Maharashtra, India Sudhir Amritphale

Alchemy Geopolymer Solutions, Ruston, LA, United States

S. Arisutha Department of Energy, Maulana Azad National Institute of Technology, Bhopal, Madhya Pradesh; Eco Science & Technology, Bhopal; Energy Centre, Maulana Azad National Institute of Technology, Bhopal, Madhya Pradesh, India Sneha Bahadure Jawaharlal Nehru Aluminium Research Development and Design Centre (JNARDDC), Nagpur, Maharashtra, India Harsh Bajpai Council of Scientific and Industrial Research (CSIR)-Advanced Materials and Processes Research Institute (AMPRI), Bhopal, Madhya Pradesh, India Manasi Buzar Baruah Department of Physics, Central Institute of Technology Kokrajhar (Deemed to be University, Ministry of Education, Govt. of India), Kokrajhar, Assam, India Sanjay Basumatary Assam, India

Department of Chemistry, Bodoland University, Kokrajhar,

Mamta Bhagat Department of Chemical Engineering, Deenbandhu Chottu Ram University of Science and Technology, Murthal, Sonepat, Haryana, India Alimpia Borah Chemical Engineering Group, Engineering Sciences and Technology Division, CSIR-North East Institute of Science and Technology, Jorhat, Assam; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India M.J. Chaddha Jawaharlal Nehru Aluminium Research Development and Design Centre (JNARDDC), Nagpur, Maharashtra, India R.G. Chaudhary Post Graduate Department of Chemistry, Seth Kesarimal Porwal College of Arts, Commerce and Science, Kamptee, India Nayaku N. Chavan Chemical Engineering and Process Development Division, CSIR-National Chemical Laboratory, Pune, Maharashtra, India Ravi Kant Choubey Department of Applied Physics, Amity Institute of Applied Sciences (AIAS), Amity University, Noida, Uttar Pradesh, India U.K. Dwivedi Amity School of Applied Sciences, Amity University Rajasthan, Jaipur, India Sourja Ghosh India

CSIR-Central Glass and Ceramic Research Institute, Kolkata,

Monti Gogoi Chemical Engineering Group, Engineering Sciences and Technology Division, CSIR-North East Institute of Science and Technology, Jorhat, Assam; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India

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Contributors

Rajiv Goswami CSIR-North East Institute of Science and Technology, Jorhat, Assam; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India Barun Haldar CSIR-Central Glass and Ceramic Research Institute, Kolkata, India S.A.R. Hashmi Green Engineered Materials and Additive Manufacturing, CSIRAdvanced Materials and Processes Research Institute (AMPRI), Bhopal, Madhya Pradesh; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India Swapnali Hazarika Chemical Engineering Group, Engineering Sciences and Technology Division, CSIR-North East Institute of Science and Technology, Jorhat, Assam; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India Vrushali H. Jadhav Catalysis and Inorganic Chemistry Division, CSIR-National Chemical Laboratory, Pune, India Amol N. Joshi Chemical Engineering and Process Development Division, CSIRNational Chemical Laboratory; Department of Chemical Engineering, Vishwakarma Institute of Technology, Pune, Maharashtra, India Jyeshtharaj B. Joshi Emeritus Professor of Eminence, Institute of Chemical Technology, Mumbai, India Pranjal Kalita Department of Chemistry, Central Institute of Technology Kokrajhar (Deemed to be University, Ministry of Education, Govt. of India), Kokrajhar, Assam, India Sanjay P. Kamble Chemical Engineering and Process Development Division, CSIR-National Chemical Laboratory, Pune, Maharashtra, India Sushil Kumar Kansal Dr. S. S. Bhatnagar University Institute of Chemical Engineering and Technology, Panjab University, Chandigarh, India Mohd. Akram Khan Industrial Waste Utilization, Nano and Biomaterials, CSIRAdvanced Materials and Processes Research Institute (AMPRI), Bhopal, Madhya Pradesh; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India Ashis Kumar Mandal CSIR-Central Glass and Ceramic Research Institute, Kolkata, India Sitendu Mandal CSIR-Central Glass and Ceramic Research Institute, Kolkata, India Nishant Markandeya Chemical Engineering and Process Development Division, CSIR-National Chemical Laboratory, Pune, Maharashtra; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India Medha Mili Green Engineered Materials and Additive Manufacturing, CSIRAdvanced Materials and Processes Research Institute (AMPRI), Bhopal, Madhya Pradesh; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India Sourav Nag

CSIR-Central Glass and Ceramic Research Institute, Kolkata, India

Biswajit Nath Department of Chemistry, Bodoland University; Department of Chemistry, Science College, Kokrajhar, Assam, India

Contributors

xiii

Rohan S. Oak Department of General Engineering, Institute of Chemical Technology, Mumbai, India Chetana R. Patil Chemical Engineering and Process Development Division, CSIR-National Chemical Laboratory, Pune, Maharashtra, India Sriparna Paul Council of Scientific and Industrial Research (CSIR)-Advanced Materials and Processes Research Institute (AMPRI), Bhopal, Madhya Pradesh, India Akm Rahman Mechanical Engineering Technology, New York City College of Technology, Brooklyn, NY, United States Suchita Rai Jawaharlal Nehru Aluminium Research Development and Design Centre (JNARDDC), Nagpur, Maharashtra, India Mohd Aseel Rizwan Dr. S. S. Bhatnagar University Institute of Chemical Engineering and Technology, Panjab University, Chandigarh, India Dilip D. Sarode Department of General Engineering, Institute of Chemical Technology, Mumbai, India N.B. Singh Department of Chemistry and Biochemistry, SBSR, Research Development Cell, Sharda University, Greater Noida, India Surinder Singh Dr. S. S. Bhatnagar University Institute of Chemical Engineering and Technology, Panjab University, Chandigarh, India S. Suresh Department of Chemical Engineering, Maulana Azad National Institute of Technology, Bhopal, India Sarika Verma Industrial Waste Utilization, Nano and Biomaterials, CSIRAdvanced Materials and Processes Research Institute (AMPRI), Bhopal, Madhya Pradesh; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India

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Preface Globally, industrialization and urbanization have increased rapidly over the past several decades, becoming an integral part of most people’s lives. Along with this growth, there has been an exponential increase in the quantity of waste materials. These waste materials can cause direct and indirect harmful effects on the environment, flora, and fauna near dumping and non-dumping areas. With the accompanying increase in scientific and technological innovations, researchers and scientists are interested in these waste materials due to their varied chemical constituents, as they can be reused in high-end advanced materials, for applications such as radiation shielding, cement-free materials, and many others. By bulk reuse of these wastes, various issues can be successfully addressed related to health care, industrial waste management, unemployment, and income generation, as well as a cleaner, greener, and safer environment. This book examines a number of studies that categorize and discuss different types of waste based on their origin and that shed light on recent and novel approaches to reuse of waste in advanced materials. The book provides details on various waste, its structural components, and the chemical constituents and mineralogical phases that could be exploited, along with the best possible way to transform various wastes into advanced materials for a number of high-end applications. Furthermore, this book showcases a novel multidisciplinary approach. The editors of this book have attempted to fill a gap by providing a platform for researchers and the scientific community to develop advanced materials by using waste as a resource material, based on simultaneous and synergistic chemical reactions among the various precursors present in the wastes as raw ingredients. The book will help provide a deeper understanding of the basic concept of waste, its sources, various types, and its reuse in value-added materials via multiple technologies, as well as future perspectives on the utility of waste products. Further, by gaining knowledge about the wastes and their bulk utilization, various issues can be better addressed in the near future, leading to safer and more sustainable development. As discussed in the book, bulk reuse of waste in current technologies will undoubtedly lead to more cost-effective development of advanced materials already in use, and can also be beneficial for researchers and scientists in implementing newer strategies to develop other materials useful over a broad application spectrum. The book examines the past, present,

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Preface

and future progress of technologies that have gained considerable attention for early, accessible, and high-end applications and provides a means for researchers to better understand the various aspects of the waste materials available as well as basic concepts of designing and developing using these wastes as no-cost raw materials for promising technologies. The book covers a range of industrial wastes useful over a variety of applications, providing in-depth knowledge of processing parameters for transforming these wastes into advanced materials for high-end applications. It is expected that this book will play a pivotal role in opening new opportunities for research, taking an ignored material from the dump into the lab and reusing it to better society. This book covers industrial waste, agricultural waste, and other wastes, such as plastics, enabling readers to use the right approach, right materials, and right processing methods in the conversion of waste into advanced materials. Although much research is still required to establish the true extent and nature of this technological approach, it is clear that converting industrial waste into advanced materials is of global concern. The book comprises 15 chapters. Chapter 1 gives an overview of industrial solid waste. Chapter 2 discusses how to explore brine sludge and fly ash waste together to make non-toxic radiation shielding material. Chapter 3 deals with the use of red mud as advanced soil stabilization material. Chapter 4 describes the conversion of agricultural biomass into valuable chemicals. Chapter 5 discusses the membrane-based treatment of wastewater generated in the pharmaceutical and textile Industries for a sustainable environment. Chapter 6 provides detailed information on the efficient and nutritive value addition of waste from the food processing industry. Chapter 7 explains waste incorporation into glass and its use as a safe and novel concept of waste utilization. Chapter 8 presents information about agricultural wastes used as sustainable and valuable products. Chapter 9 deals with the uses of industrial waste for valueadded products. Chapter 10 discusses the conversion of agriculture, forest, and garden waste for an alternative energy source. Chapter 11 explores the innovative possibilities in the pursuit of long-term sustainability of agricultural waste. Chapter 12 covers utilization of value-added products from fly ash. Chapter 13 describes the role of advanced geopolymers in utilizing industrial wastes to achieve a zero-waste concept. Chapter 14 discusses the waste from glass fiber reinforced polymeric composites. Chapter 15 presents information on muga silk as a sustainable material for emerging technology. Sarika Verma Raju Khan Medha Mili S.A.R. Hashmi Avanish Kumar Srivastava

Acknowledgments The editors sincerely thank each chapter author for their contributions to this book. Their sincere efforts, dedication, hard work, and analytical approach are highly acknowledged. The editors also acknowledge publishers and associated teams for offering continuous support, guidance, and motivation, which constantly pushed them forward to complete the book. Dr. Sarika Verma expresses her special thanks to her parents, husband, and sons for their everlasting love, enthusiasm for science, and encouragement to pursue every task successfully. Further, the editors—Sarika Verma, Raju Khan, Medha Mili, S.A.R. Hashmi, and Avanish Kumar Srivastava—sincerely thank all those who have directly or indirectly rendered valuable input to the book.

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C H A P T E R

1 Industrial solid waste: An overview N.B. Singha and R.G. Chaudharyb a

Department of Chemistry and Biochemistry, SBSR, Research Development Cell, Sharda University, Greater Noida, India, bPost Graduate Department of Chemistry, Seth Kesarimal Porwal College of Arts, Commerce and Science, Kamptee, India

1.1 Introduction There are number of factories, industries, mills, mining plants, etc. throughout the world. These industries produce finished goods for consumers from raw materials. However, in the process of manufacturing, by-products are formed which are considered useless [1,2]. They constitute the industrial waste. In addition, there are agricultural wastes, municipal solid waste, and hazardous wastes. With urbanization and faster economic developmental need, all kind of wastes are being generated heavily. Waste is often subjective “(because what is waste to one need not necessarily be waste to another).” Basel Convention by UNEP defines wastes “as substances or objects, which are disposed of or are intended to be disposed of or are required to be disposed of by the provisions of national law.” Industrial wastes may be solid, semisolid, liquid, and gaseous. Every year, huge amount of industrial wastes are produced and become a threat to environment and human health. Because of nonavailability of appropriate technologies, developing countries face major problems in disposal and management of industrial waste. Out of different wastes, solid wastes such as municipal and industrial wastes pose lot of problems from different point of view.

Advanced Materials from Recycled Waste https://doi.org/10.1016/B978-0-323-85604-1.00018-4

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Copyright © 2023 Elsevier Inc. All rights reserved.

2

1. Industrial solid waste: An overview

FIG. 1.1 Reducing, reusing and recycling of wastes [1].

Commonly discarded wastes by the public are known as municipal solid wastes (MSWs). These materials are lawn furniture, packaging materials, clothing materials, cuttings, bottles/glasses, electric appliances, food scraps, batteries, newspapers, paint, etc. [3]. Out of different types of solid wastes, industrial solid wastes (ISW) have attracted a lot. ISW includes all types of reusable, nonreusable, hazardous, nonhazardous, recyclable, and nonrecyclable wastes [4,5]. Despite different regulations and precautions, ISW generation is increasing with a very fast rate. Attempts are being made to minimize waste products. The end-of-life for any waste product is related to its volume, and available collection and processing infrastructure. Waste should be managed in order of “(i) prevention; (ii) preparing for re-use; (iii) recycling; (iv) other recovery, e.g., energy recovery; and (v) disposal.” However, the major ways to minimize ISW are recycle (1st R), reuse (2nd R), and reduce (3rd R) (Fig. 1.1) [1]. The three R concepts consider economics, natural resource savings, and energy savings, hence result in minimizing the obtained ISW and their health and environmental impact and the wastes. In this chapter, generation, characterization, management, and use of different industrial solid wastes have been discussed in detail.

1.2 Classification of ISW ISWs can be divided into four categories depending on their nature, pollution characteristics, sectors and process as discussed below.

1.2 Classification of ISW

3

1.2.1 According to nature The ISW based on the nature has been classified into (i) organic and (ii) inorganic industrial solid wastes (OISW, IISW). OISW contains organic compounds and are generated in number of industries like oil extraction, painting, tanning, dyeing, food preservation, water treatment stations and plastic industries. The OISW quantity and their physical shape depend on the technologies used and the source. The source of OISW is arranged in the following order: “Water treatment stations < wood manufactories < oil extraction < plastic, food preservation < painting, dying and tanning.” The OISWs with polymeric nature are produced from plastic and organic chemical manufacturing industries. OISW, of herbal nature, is obtained from waste produced from wood, food preservation, and oil extraction industries [1]. The IISWs are generated from industries such as ceramic, cement, and granite manufacturing. The dusts generated in cement industries are very hazardous solid waste. In general, IISWs are more hazardous than OISWs. The amount of IISWs generated from industries is arranged in the sequence “cement < ceramic < granite and marble.”

1.2.2 Per pollution characteristics The ISWs are hazardous and nonhazardous. The hazardous ISWs (HISWs) need special action as per characteristics. HISWs pose various types of environmental and health problems and so they are stored and treated in a special way depending on their hazardous nature. The Nonhazardous ISWs (NHISW) do not require any special considerations. They can be reused or recycled.

1.2.3 According to industrial sectors These solid wastes can be divided into five categories: (i) mining industries solid waste (MISW), (ii) metallurgical industry solid waste (MEISW), (iii) chemical industries solid waste (CISW), solid wastes from food preservation industries (FISW), and (v) solid wastes from construction industries.

1.2.4 Industrial process As per industrial process, waste is classified to fired ISW (FISW) and unfired ISW (UFISW). All FISWs are obtained by firing. The examples are fired steel waste, fired ceramic waste, cement dust and fired bricks waste [1]. All UFISWs are obtained without firing. The examples are granite and marble waste, food preservation waste, waste from paper industry and unfired

4

1. Industrial solid waste: An overview

Fly ash

Blast furnace slag

Agricultural wastes

Electronic wastes

Waste Tire

Waste Glass

Plastics wastes

Construction Industry wastes

Paper wastes

Household

Wood wastes

(A)

(B) FIG. 1.2 (A) Different solid wastes and (B) classification of ISW and [1].

ceramic waste [1]. Different types of solid wastes are given in Fig. 1.2A and different category is subdivided into number of categories (Fig. 1.2B) [1].

1.3 Wastes from different industries: Generation, properties and uses In this section some important solid wastes from different industries have been discussed.

1.3 Wastes from different industries: Generation, properties and uses

5

1.3.1 Coal fly ash (FA) Fly ash (FA), also known as pulverized fuel ash (PFA), is a fine powder obtained from the combustion of powdered coal in electric generating plant. Temperature may exceed 1600°C during burning process and may melt most of the inorganic materials present in the coal. The inorganic matter present in it gets fused during combustion of coal. After or during combustion, mineral matters within the coal or excluded, liquefy, vaporize, condense or agglomerate [6]. Amorphous and spherical particles of FA are obtained by rapid cooling in the postcombustion zone due to surface tension. FA produced from thermal power plants are in large quantities and create pollution. By reusing FA, environmental pollution can be minimized. Fly ashes obtained from different variety of coals have different compositions and are generally Tan to dark gray.

1.3.1.1 Classification of FA There are two grades of FA based on IS 3812–1981. Fly ash-I is obtained from bituminous coal with SiO2 + Al2O3 + Fe2O3
70%, whereas fly ash-II is obtained from lignite coal with SiO2 + Al2O3 + Fe2O3
50%. As per ASTM C618, Class C and Class F FA have been specified based on coal type and the chemical composition. Class C fly ash has CaO higher than 10% and has cementitious as well as pozzolanic properties and normally obtained from the combustion of lignite or sub bituminous coals. Class F fly ash, obtained from the combustion of bituminous or an anthracite coal with CaO below 10%, has pozzolanic properties.

1.3.1.2 Physical properties of FA Some of the physical properties of FA such as bulk density, specific gravity, plasticity, free swell index, porosity, surface area, lime reactivity, coefficient of uniformity, optimum moisture content, shear strength friction angle, etc. are given in Table 1.1 [7].

TABLE 1.1 Physicochemical properties of FA [7]. Property

FA 3

Bulk density (kg/m )

900–1300

Specific gravity

1.6–2.6

Clay

Negligible

Plasticity

Nonplastic

Porosity (%)

30–65 Continued

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1. Industrial solid waste: An overview

TABLE 1.1 Physicochemical properties of FA—cont’d Property

FA

Free swell index

Very low

Surface area (m2/g)

5

Lime reactivity (MPa)

1–8

Extreme particle size (mm)

0.001–0.1

Coefficient of uniformity (%)

3.1–10.7

pH

6–8

226

288

40

180–500

Ra

K

feta

260

232

130

238

192

Th U

Absorption (%)

12.25

3

Density (kg/m )

1380 3

Maximum dry density (kg/m )

640–1440

Optimum moisture content (%)

45.5%

Los Angles abrasion (%)

28.35%

Shear strength friction angle

34°

California bearing ratio (%)

10

Permeability coefficient (cm/s)

106–104

1.3.1.3 Composition of FA FA consists of number of oxides such as Al2O3, MgO, Fe2O3, SiO2, Cao, Na2O, K2O SO3, TiO2, etc., which depend on the type of the coal and combustion technology. Compositions of FA obtained from different type of coals are given in Table 1.2 [7]. 1.3.1.4 Characterization of FA The most common techniques for characterization of FA are X-ray diffraction, FTIR, and scanning electron microscopic (SEM) techniques. X-ray diffraction pattern of FA generally shows broad halo band between 2θ ¼ 22°–35° due to amorphous nature [8]. Various other crystalline phases such as mullite (M), iron oxide (Fe) (hematite and/or magnetite), and

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1.3 Wastes from different industries: Generation, properties and uses

TABLE 1.2 Composition of FA obtained from different coals [7]. Component (mass%)

Bituminous

Subbituminous

Anthracite

Lignite

Al2O3

5–35

20–30

25.1–29.2

10–25

MgO

0–5

1–6

0.7–0.9

3–10

Fe2O3

10–40

4–10

3.8–4.7

4–15

SiO2

20–60

40–60

43.5–47.3

15–5

CaO

1–12

5–30

0.5–0.9

15–40

Na2O

0–4

0–2

0.2–0.3

0–6

K2O

0–3

0–4

3.3–3.9

0–4

SO3

0–4

0–2

–

0–10

TiO2

0.5

1.1–1.2

1.5–1.6

0.23–1.68

P2O5

0.02

0.3–0.5

0.2

–

MnO

0.02

0.1

0.1

0.04–0.21

S

0.08–0.67

0.7

0.1

–

LOI

0–15

1.8–2.7

8.2

0–5

quartz (Q) are seen. FTIR spectra of fly ash shows number of vibrational bands due to the presence of O-H, Si-O-T (T ¼ Si or Al) and Fe-O groups [8]. SEM studies have shown that the FA particles are spherical in shape and consist of cenospheres, solid spheres, porous unburnt carbon, and irregular-shaped debris [9]. 1.3.1.5 Applications of FA Depending on the source, the composition of FA varies and accordingly used in different sectors especially in civil engineering and construction [10]. Due to the presence of number of elements, it is used as nutrients in soil, precursor to synthesize zeolites, mesoporous silica, and carbon nanotubes. Fly ash polymer composites are being synthesized for number of applications. It acts as an adsorbent to capture some polluting gases from atmosphere and purification of water as an adsorbent. Some important applications of FA are given in Fig. 1.3 [9] and discussed in the following sections. 1.3.1.5.1 FA in concretes

One of the major applications of FA is in construction industry. When Portland cement (OPC) is mixed with FA in appropriate amounts, blended cements are formed. This improves the quality of cement and at the same

8

1. Industrial solid waste: An overview

Recover germanium, vanadium, gallium, titanium and tals me aluminium able valu ing tain Con

Catalysts Catalysts support

Low bulk density Abundant resources

Containing various Mixture metallic oxides; Higher of particles stability of aluminosilicates; varying in Higher specific surface area shape, size, and composition

Removal of P, B, phenolic compounds, dyes from wastewater; Capturing CO2, NOX from flue gases

Chemicals and minerals complex

Recover cenospheres, unburnt carbon and magnetic spheres

Silt and clay-sized particles

Cement/blended cement raw material; Bricks/concrete blocks; Concrete additive; Geopolymers

Mine soils/other soils Higher amelioration water-holding capacity; Favorable pH; Source of essential plant nutrients Containing / unburnt carbon; ious entit r ties Ne ga Cem tively charged rope nic p surface at high zola pH Poz

Sintered materials; Containing Glass-ceramic; silica, alumina, Glass iron, etc; Physicochemical parameters resemble with volcanic ash, natural soil

Simil Zeolites; Mesoporous ar co mpo with materials sit v o lc a nic m ions ateria l

FIG. 1.3 Applications of fly ash in different areas [9].

minimizes environmental pollution. The quantity of FA in concrete varies from 15% to 30%. Replacement from 30% to 50% by FA has also been used for large structures like foundations and dams for controlling the temperature rise. During hydration of OPC, Ca(OH)2 is produced, which in due course reacts with silica of FA forming calcium silicate hydrate, the main glue of the cement [6]. This additional amount in due course increases the strength. In the presence of FA, early strength is decreased, but at the latter stage, it is increased. So it has a beneficial effect. FA in larger amounts also acts as an aggregate. 1.3.1.5.2 Fly ash bricks

Bricks of FA are made with Class C FA and water by compressing at 4000 psi and curing at 70°C for 24 h in a steam bath. Air entrainment agent is also added. Since C class FA has enough CaO, the brick formed is selfcementing. It is a better alternative to conventional brick. It is economical, energy saving and protect environment. FA bricks are used for power plants, homes, factories, warehouses, high-rise structures, etc. 1.3.1.5.3 Fly ash based geopolymer cement

Geopolymers are green binding materials and considered as potential substitute of Portland cement. It is made by activating materials containing aluminosilicate minerals with alkaline solution and alkali silicate

1.3 Wastes from different industries: Generation, properties and uses

FIG. 1.4

9

Synthesis of geopolymer cement and concrete using FA as precursor [11].

solution. Variety of aluminosilicate materials like fly ash, feldspar, kaolinite, geolite, industrial, and agricultural waste can be used as precursor for preparing geopolymers. The chemical and mineralogical compositions play an important role during geopolymerization. Out of different precursors, FA is the most important one. On combination of FA and alkaline activators in appropriate amounts and curing at appropriate temperature, geopolymer cement and concrete are formed (Fig. 1.4) [11]. Geopolymer cement formed can be cured at 80°C and is much more durable and gives early high strength. The cement and concrete made from geopolymer is environment friendly, economical and more durable as compared to OPC concrete. 1.3.1.5.4 Fly ash in soils

Properties of soils are affected by addition of FA [12]. The acidic or basic nature of FA which very much depends on the source, buffers soil pH. By addition of FA, electrical conductivity of soil increases, increasing the metal content. CaO present in FA reacts readily with acidic components of soil and releases nutrients such as B, S and Mo beneficial for crop plants. FA increases nutrients of soil and thus increases crop production by increasing the availability of Ca2+, Mg2+ in soil and preventing toxic effects of Al3+ and Mn2+ and other metallic ions by neutralizing the soil acidity. 1.3.1.5.5 Water purification by FA

Now a days, adsorption technique is being used for water purification for removing heavy metal ions, inorganic compounds, dyes and other organic compounds from water using suitable adsorbents. Number of adsorbents is being used and FA may also be a potential adsorbent. However, its adsorbing capacity is poor so FA is activated, modified, and

10

1. Industrial solid waste: An overview

transformed into efficient adsorbents. Depending on the quality of FA, right treatment is needed. In future, the activated/modified FA is going to be an economical and very good adsorbent for water remediation [10].

1.3.2 Blast furnace slag (BFS) In many countries, economy depends on iron and steel manufacturing industries. The basic materials for the development and maintenance of infrastructures are obtained from steel and iron. However, these industries are also responsible for generation of large amounts of solid wastes, primarily in the form of steel slag, known as a glass or gravel like by-product [13,14]. The worldwide production of steel slag is more than 1600 million tons annually [15–17]. BFS is categorized based on the process in which it was generated (basic oxygen furnace slag (BOF-S), electrical arc furnace slag (EAFS), ladle refining slag (LFS)), or by the type of steel produced in said process (carbon steel slag or stainless-steel slag). Typical chemical composition of BFS is as SiO2 (30%–35%), Cao (28%–35%), MgO (1%–6%), and Al2O3/Fe2O3 (1.8%–2.5%). 1.3.2.1 Reuse and recycling of blast furnace slag Blast furnace slags are used in number of areas such as Cement and concrete, agriculture, soil stabilization, waste water treatment, fuel development, CO2 capture, road and pavement, etc. [18]. However, maximum use is in construction industry and discussed below. 1.3.2.1.1 Slag in cement and concrete

Toward a circular economy, the valorization of EAF, BOF, and LF slags is an important process for waste management. One of the most important applications is the use in cement and concrete production. Ten percent to 20% BOF slag is used as supplementary cementitious materials in cement and concrete with satisfactory performance. BOF slag is also used as aggregates in concrete. The reactivity of slags is enhanced by mechanical, thermal and chemical activations [19]. BFS has cementitious properties, and the products of hydration are similar to those of Portland cement. [20]. When it is used as mineral admixture, it reduces the heat evolution of cement and decreases early strength of concrete [21,22]. As BFS has pozzolanic properties, react with Ca(OH)2 [23] produced during the hydration of Portland cement and forms additional amount of C-S-H which fills the pores. This makes the concrete dense and more durable [24,25]. BFS is also used as an aggregate in concrete. Different slags have different effects [26].

1.3 Wastes from different industries: Generation, properties and uses

11

1.3.2.2 Ferro nickel slag When nickel ore and bituminous coal are melted at high temperatures, ferronickel slag (FNS) is obtained as an industrial by-product. FNS mainly consists of MgO, SiO2 and Fe2O3. This contains amorphous silica and crystalline minerals. The chemical composition depends on processing, source and method of cooling. FNS acts as a binder and fine aggregate in geopolymer and Portland cement concretes. FNS improves the durability and strength of concrete. FNS in cement acts as a pozzolanic material similar to fly ash. Geopolymer blended with 20% FNS gives superior properties as compared to 100% fly ash–based geopolymers. FNS acts as an alternative to natural aggregate in pavement construction [27].

1.3.3 Rubber tires About 1.4 billion Tires come in the market every year and almost same amount comes as waste (discarded after the end of their life). Disposal of tire rubber wastes is now a major environmental problem all over the world and is a serious threat to the ecology [28]. The used and disposed tires are cut into pieces for disposal and recycling. Carbon black (CB) (25–35 wt%), Rubber (60–65 wt%) and the accelerators and fillers together form Tires. Depending on trademark and use, numbers of materials are added during the manufacturing of tires. Used rubber tires can be reused and recycled in number of ways as discussed below. 1.3.3.1 Waste tires into useful products Tires are made in such a way that they can withstand harsh conditions. Tires are nondegradable or take long time for degradation because of cross-linking of vulcanized rubber with sulfur bonds. The waste tires can be recycled/reused as a new rubber product such as a sports surfacing playground, civil engineering application, rubber modified asphalts, wheel chocks, doormats, gaskets, and railroad crossing mates. Lot of researches is being carried out to find suitable methods for recycling and reuse of waste tires. Among different methods, pyrolysis (thermal decomposition in oxygen free atmosphere) based recycling technique has been considered better [29]. Other method of disposal of waste tires (WT) and conversion into useful product is thermochemical method. This method reduces environmental problems and produces lot of useful products (Fig. 1.5) [30]. 1.3.3.2 Rubber in concrete The recycled WT rubber can be used as a replacement of fine aggregates, coarse aggregates, binders, and fibers in concrete. Moreover, WT rubber can be utilized in other cementitious composites, such as polymer

12

1. Industrial solid waste: An overview

FIG. 1.5 Thermochemical method for disposal of WT and production of useful products [30].

composites, geopolymers and in mortars. Properties of concretes in presence of WT are modified considerably. Rubberized concrete shows high resistance to acid attack, chloride ion penetration and freeze–thaw [31].

1.3.4 Used glasses Glass is manufactured at high temperature by melt quench method using variety of materials. Depending on the composition, there are varieties of glasses. Some of the glasses are: soda-lime glass, sodiumborosilicate glass, fused-silica glass, aluminosilicate glass, lead-oxide glass and germanium-oxides glass. [32]. Most of the used and waste glasses are obtained from food, pharmaceutical, motor vehicle manufacture and construction industries. Glasses are first considered for their reuse and after that for recycling. Waste glasses (WG) can be utilized as a partial replacement of aggregate in concrete production. It is reported that finer glass particles can enhance the hydration process increasing the amount of C-S-H gel. Different glasses have different chemical composition and hence have different reactivity. In the

1.3 Wastes from different industries: Generation, properties and uses

13

presence of WG, the workability, mechanical properties and the durability of concrete are modified. However, detail research is needed [33]. Depending on the composition, WG obtained from different sources can be used in the preparation of alkali activated materials (AAMs). Different oxide contents in WGs affected the reactivity to different extent to hydration products and the performance of AMMs. Reuse of WGs affects the properties of AAM mortars. Use of WGs as fine aggregates may increase the fresh properties, but gives erratic strength. Microstructural studies have shown that the long-term reaction on the surface of glass particles leads to the integration of fine glass aggregates and the matrix. It also improves sulfate attack and stability at high temperature. With the use of WGs durable strength cannot be achieved. The presence of WGs improves the resistance of AAMs to dry shrinkage and sulfate attack but does not induce a significant ASR expansion. Efflorescence can be restrained [32].

1.3.5 Silica fume Silicon and ferrosilicon alloy industries produce silica fume (SF) as a by-product. SF is obtained at high temperatures (2000°C) by the reduction of quartz on heating with coal, coke or wood chips in an electric arc furnace. It is a very fine non crystalline solid (85%–95%). It is a very good pozzolanic material and when added in cement and concrete, improves the properties considerably. Although it has number of advantages in construction industry, it is harmful to human health because of very small size. This enters lungs, digestive tract, and skin easily. The problem can be minimized by using slurry.

1.3.6 Plastic wastes Plastics are long-chain organic polymers with high molecular weights. Plastics are derived from petrochemical industry. Plastics are basically thermoplastics and thermosets. Thermoplastics can easily be molded, i.e., when heated, they are softened and when cooled can be again molded. On the other hand Thermosets like Bakelite and Melamine cannot be molded after heating. There are number of thermoplastics, which have different properties and applications (Fig. 1.6). Plastics are being used in different sectors in large amounts and after use, they are being thrown, which creates lot of environmental and disposal problems. During this COVID period, the use is increased considerably and accordingly the plastic wastes [34]. Number of methods has been developed for the management of waste plastics (Fig. 1.7). Mainly four approaches have been adopted for recycling of waste plastics. They are primary, secondary, tertiary and quaternary recycling [35]. Recycling

14

1. Industrial solid waste: An overview

FIG. 1.6 Different plastics for different applications.

technique plays an important role in the generation of new polymer. Every technique has its own merit and demerit. The use and disposal of plastic wastes can be handled if there is a change in personal and institutional behavior. There are number of ways, how this can be done (Fig. 1.8) [34].

1.3.7 Agro industrial wastes Agricultural, industrial and municipal activities generate bio-wastes. Crop residues and livestock manure are the agricultural bio-wastes, whereas municipal bio-wastes consist of organic wastes coming from urban areas, market waste, municipal solid waste and food waste On

15

1.3 Wastes from different industries: Generation, properties and uses

Plastic waste management

Mechanical Recycling

Palletizing

Feed Stock Recycling

Energy Recovery

Pyrolysis

Incineration

Extrusion

Gasification

Coincineration

Injection Molding

Waste to fuel

Drawing

Shedding

FIG. 1.7

Plastic waste management.

FIG. 1.8

Suggestions for minimizing plastic wastes [34].

Landfill

16

1. Industrial solid waste: An overview

FIG. 1.9 Agricultural biowaste management [36].

the other hand industrial bio-wastes consist of paper, palm oil, coir, textile, sugar, food processing, mushroom, dairy, tannery, forest, sago, bakery, and wood processing and most of these industries are connected with the agricultural sector. Agricultural waste/biowastes such as processing residue, crop straw, husk, domestic garbage and skins of fruit if not disposed off properly, create environmental and health problems. There are number of agricultural wastes which can be converted to some useful materials as given in Fig. 1.9 [36]. Agricultural wastes heated (i.e., 350–700°C) in the absence of oxygen, produce biochar [36]. The process, activation, and uses of biochars are given in Fig. 1.10. Different types of biochars obtained from different feed stocks (i.e., wood pine chip, garlic stem, rice husk, soybean stover, tea waste, perilla, and oak wood) under different conditions have been studied [36]. Solid state fermentation of agricultural wastes gives lot of useful products [37]. Numbers of raw agricultural wastes are being used as adsorbents for removal of pollutants from water. It is reported that orange peel is used for the adsorption of manganese, iron and copper metal ions from aqueous solution. Surfactant modified orange peel showed better removal of metal ions. Adsorption is also affected by pH, the highest adsorption occurred at pH 6.0 [38]. Bamboo shoot skin has been used for the removal of methylene blue dye from aqueous solution and the maximum adsorption capacity was found to be 29.88 mg/g. Agricultural waste generated from cauliflower leaves were used to prepare bioadsorbent for the removal of methylene blue dye [39]. Durian peel, natural product bagasse,

FIG. 1.10 Conversion of biochar [36].

18

1. Industrial solid waste: An overview

coconut shell, walnut shell, castor seeds, palm fruit biomass, rice husk, and sugarcane bagasse are reported as good bioadsorbent for removal of dyes, metal ions, and oil by-products from polluted water [40–42]. Rice husk is considered as a lignocellulosic waste material of low value. It has been reported as a potential adsorbent for removal of cadmium, chromium and phenolic compounds from water [43]. Rice husk has been used as fixed bed column for the removal of Tl3+ from aqueous solution. Cucumber peal powder is used as adsorbent for removal of methylene blue dye [44]. The adsorbent can be regenerated. Watermelon rind is used for removal of heavy metal ions and dyes from water. The maximum dye adsorption capacity 231.48 mg/g for methylene blue and 104.76 mg/g for crystal violet between pH 8 and 11 was obtained [45].

1.3.8 Dairy wastes The milk and its products are very essential foodstuff of the whole world. The dairy products are one of the best sources of food constituents of human being. The important dairy products can be obtained from the dairy industry like skim milk, butter, cheese, casein channa, paneer, ghee, whey, and so forth. Day-by-day manufacturing of dairy products is increasing and as a result waste products are generated. Effluents from dairy industries are responsible for environmental impact [46]. Lot of wastes obtained from milk fermentation or by-products from the processing could be used for obtaining other dairy products. The other dairy products are whey concentrates from cheese whey. There are suspended solids and organic matter in dairy wastes which contain high content of nitrogen and phosphorous and the presence of oil and greases. Lot of wastewater is also obtained by dairy industries [47]. There are number of methods such as wetland (natural process), physicochemical process (coagulation/flocculation), and biological processes (trickling filters, aerated lagoons, activated sludge, up flow anaerobic sludge blanket, anaerobic filters and sequential batch reactors) by means of which dairy wastes can be treated [46].

1.3.9 E-waste and their recycling E-waste means an electronic waste. It is a trash generated from broken, obsolete, and surplus electronic devices. Typically, these e-wastes consist of noxious chemicals and hazardous materials. Electronic waste is a big issue of the whole world. Hence, an e-waste must be recycled and reused in order to avoid dumping and environmental risks. The e-waste recycling is important, but the number of recent studies disclosed that it is dangerous to health and environment [29]. E-waste recycling refers to the

1.3 Wastes from different industries: Generation, properties and uses

19

reprocessing and reuse of dismantled electronic wastes. E-waste has created a significant communal and political awareness due to rise in the generation of e-waste, recover precious elements, and recycling e-waste. A number of main responses to the rising generation of e-waste have included technological innovations in recycling processes, and the shift of e-waste among the familiar and official recycling segments. Numbers of elements are found in e wastes. For example cell phone contains elements like copper, tin, cobalt, indium, antimony, silver, gold, and palladium [48], which can be used as secondary raw materials. Consumer electronic waste from smaller items has not been profitable to recycle because of high labor charges, as the quantity of recoverable precious materials is relatively low. Hence, these materials have typically either been disposed of, stored or exported to undeveloped countries where they are recycled using low-tech methods to recover gold, copper and other expensive metals. These techniques produced livelihoods for workers but they infected with hazardous toxic chemicals. Basically, e-waste recycling process consists of five basic stages: collection, toxics removal, preprocessing, end processing and disposal [49]. E-wastes are managed worldwide by different techniques. An e-waste may be collected informally via “waste pickers” or by informal collectors have achieved significantly higher recycling rates than those where waste is dropped off through normal channels [50]. Metals present in e wastes, get contaminated with soil and reach to different parts of plants, where from humans get contaminated. There are number of routes through which these metals enter into human body and create lot of health problems [51].

1.3.10 Industrial waste as heat recourse The term “waste-to-energy” is used interchangeably and responsible for different processes and technologies. Different waste materials can act as heat resource, i.e., can be converted to energy. Some of the conversion processes of waste into energy are given in Fig. 1.11 [52].

1.3.11 Bioremediation of industrial wastes The most crucial environmental concern is Earth pollution caused by noxious desecrates effluents and uncontrollable organic compounds due to human activity. Among the variety of pollutants, lethal sources of pollutants are industrial influents such as polycyclic aromatic hydrocarbons, organic dyes, sulfur oxide, organic solvents, and burning waste, i.e., plastics waste which produces dioxins and chlorinated compounds. These hazardous chlorinated compounds are produced from the industry effluent that causes mutagenic and carcinogenic effects to humans being.

20

FIG. 1.11

1. Industrial solid waste: An overview

Conversion processes for waste to energy [52].

Basically, industrial wastes are being produced by an industrial activity during the process of materials manufacturing like masonry, dirt, gravel, concrete, scrap metal, chemicals, oil, scrap lumber, solvents, and so forth. Indeed, industrial wastes are hazardous in the form of liquid, solid, or gaseous, and pollute to soil, air, water, and sea. Hence, the contamination of air, soil, and water by lethal compounds causes high risks of carcinogenic effects to humans being and environment too. Unquestionably, an explosive development resulted environmental deterioration by fast industrialization and utilize harmful substances such as hydrocarbons, chlorinated organo-phosphorus, nitro-aromatic compounds, heavy metals, and pesticides [53]. Number of elements obtained from industries in the form of waste is toxic to human health and environment. To avert the spread of toxic compounds, pollution and environmental deterioration, a green and biological approach is being needed for triumphant cleaning. Biogenic remedy is the good techniques which involve microbes, algae, fungi (Mushroom), protozoa, and plants to eliminate environmental pollutants with eco-friendly. The bioremediation strategy is predominantly depends upon the metabolic mechanism of the microorganism to degrade the pollutants. One of the best techniques in bioremediation is a biofilm. Microorganisms are residing in the biofilm with

1.4 Conclusions and future prospects

21

cooperative manner, benefiting to each other by ecological niches system. The microorganism communities are governed partly by the structure, diffusion of nutrients, and physiological activity of the cells [54]. In recent years, severe ecological issues became prevalent due to rapid growth of civilization and industrial progress [55,56]. Especially, textiles industries released the diverse types of highly toxic pollutants. The colored textile wastewater is enriched in dyes, numerous of them are noxious, carcinogenic, and mutagenic. Among synthetic dyes, indigocarmine (IC) and methylene-blue (MB) are distinctive rebellious and highly tenacious dyes [57,58]. Although, these dyes are toxic but they can be completely degraded by biogenic-reduction techniques. The few decades ago reports revealed that dyes degradation can be done by Pseudomonas strains, black liquor pulp mill effluents by Pseudomonas putida. Moreover, a few anaerobic microbes such as Streptomyces and fungi (Phaenerochaete chrysosporium) were employed for decoloration of chromogenic dyes. Bacteria (Methanosarcina, Methanosaeta, Clostridium, Bifidobacterium, Bacteroides, Clostridium perfringens, and so forth), algae (Chlorella, Anabaena inaequalis, Westiellopsis prolifica, Stigeoclonium, and so forth), fungi (Rhizopus arrhizus, Aspergillus niger, Penicillium spinulosum, Trichoderma viride, Saccharomyces cerevisiae, and so forth), actinomycetes, protozoa, and plants have been used to extracts the toxic metals. The numerous type microorganisms like Chlorella, Anabaena, marine algae were employed for the elimination of toxic metals. Fungi are also capable of accumulating toxic metals in their cells. Nevertheless, tactic approach can be applied by fungi to eliminate the toxic metals from the solution. Principally, negatively charged ligands (species) in cell are attracted to the positively charged toxic metals ions, and extraction can be executed. For example, in Rhizopus arrhizus adsorption depends on ionic radius of Mn2+, Li3+, Ba2+, Zn2+, Cu2+, Hg2+, Cd2+, Ni2+, and Pb2+. However, binding of A13 +, Ni2+, Hg2+, Cd2+, Cu2+ and Pb2+ strongly depends on concentration of microbe cells. Likewise, bioremediation of coal waste land through vesicular-arbuscular mycorrhiza fungi is gaining significance in the current years.

1.4 Conclusions and future prospects The old saying “Waste not, want not” appears to be true. Due to industrialization, urbanization, and increase in living standards, we have lot of environmental problems. Environmental problems are due to generation of wastes particularly industrial solid wastes. Industrial wastes come from different processes and different product residues. The waste may differ

22

1. Industrial solid waste: An overview

from industry to industry but they are of three types, solids, liquids, and gaseous. Wastes generated may act as a by-product for growth. Awareness of different type of industrial solid wastes and their utility and recycling is needed. In this chapter, brief information about solid wastes generated from different industries is discussed. Methods have been discussed to remove the wastes. However, microbial remediation technologies are considered better, but a lot of work is to be done on this methodology. It is to be noted that if the wastes can be converted into materials which can act as raw material for production of other type of materials, cost of production and environmental pollution will be reduced. It is recommended that researches be carried out to convert wastes into useful materials. Overall, continued efforts should be made to use, reuse and recycle the wastes considering the economics.

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[16] J. Liu, D. Wang, Influence of steel slag-silica fume composite mineral admixture on the properties of concrete, Powder Technol. 320 (2017) 230–238. [17] P.S. Humbert, CO2 activated steel slag-based materials. A review, J. Clean. Prod. 208 (2019) 448–457. [18] V.A. Nunes, P.H.R. Borges, Recent advances in the reuse of steel slags and future perspectives as binder and aggregate for alkali-activated materials, Constr. Build. Mater. 281 (2021) 122605. [19] J. Li, Q. Yu, J. Wei, T. Zhang, Structural characteristics and hydration kinetics of modified steel slag, Cem. Concr. Res. 41 (3) (2011) 324–329. [20] S. Liu, L. Li, Influence of fineness on the cementitious properties of steel slag, J. Therm. Anal. Calorim. 117 (2) (2014) 629–634. [21] S. Mengxiao, W. Qiang, Z. Zhikai, Comparison of the properties between high-volume fly ash concrete and high-volume steel slag concrete under temperature matching curing condition, Constr. Build. Mater. 98 (2015) 649–655. [22] H.N. Atahan, D. Dikme, Use of mineral admixtures for enhanced resistance against sulfate attack, Constr. Build. Mater. 25 (8) (2011) 3450–3457. [23] A. Attari, C. McNally, M.G. Richardson, A combined SEM – calorimetric approach for assessing hydration and porosity development in GGBS concrete, Cem. Concr. Compos. 68 (2016) 46–56. € [24] E. Ozbay, M. Erdemir, H.I. Durmus¸ , Utilization and efficiency of ground granulated blast furnace slag on concrete properties – a review, Constr. Build. Mater. 105 (2016) 423–434. [25] O. Gencel, O. Karadag, O.H. Oren, T. Bilir, Steel slag and its applications in cement and concrete technology: a review, Constr. Build. Mater. 283 (2021) 122783. [26] Y. Jiang, T.-C. Ling, C. Shi, S.-Y. Pan, Characteristics of steel slags and their use in cement and concrete—a review, Resour. Conserv. Recycl. 136 (2018) 187–197. [27] A.K. Saha, M.N.N. Khan, P. Kumar Sarker, Value added utilization of by-product electric furnace ferronickel slag as construction materials: a review, Resour. Conserv. Recycl. 134 (2018) 10–24. [28] A. Sof, Effect of waste tyre rubber on mechanical and durability properties of concrete – a review, Ain Shams Eng. J. 9 (2018) 2691–2700. [29] C. Sathiskumar, S. Karthikeyan, Recycling of waste tires and its energy storage application of by-products – a review, Sustain. Mater. Technol. 22 (2019), e00125. [30] M. Arabiourrutia, G. Lopez, M. Artetxe, J. Alvarez, J. Bilbao, M. Olazar, Waste tyre valorization by catalytic pyrolysis – a review, Renew. Sust. Energ. Rev. 129 (2020) 109932. [31] B.S. Thomas, R. Chandra Gupta, A comprehensive review on the applications of waste tire rubber in cement concrete, Renew. Sust. Energ. Rev. 54 (2016) 1323–1333. [32] Y. Liua, C. Shia, Z. Zhanga, N. Lia, An overview on the reuse of waste glasses in alkaliactivated materials, Resour. Conserv. Recycl. 144 (2019) 297–309. [33] S. Chandra Paul, B. Sˇavija, A. John Babafemi, A comprehensive review on mechanical and durability properties of cement based materials containing waste recycled glass, J. Clean. Prod. 198 (2018) 891–906. [34] K. Raja Vanapalli, H. Bhakta Sharma, V. Prakash Ranjan, B. Samal, J. Bhattacharya, B.K. Dubey, S. Goel, Challenges and strategies for effective plastic waste management during and post COVID-19 pandemic, Sci. Total Environ. 750 (2021) 141514. [35] N. Singh, D. Hui, R. Singh, I.P.S. Ahuja, L. Feo, F. Fraternali, Recycling of plastic solid waste: a state of art review and future applications, Compos. Part B 115 (2017) 409–422. [36] B. Ravindran, N. Karmegam, A. Yuvaraj, R. Thangaraj, S.W. Chang, Z. Zhang, M. Kumar Awasthi, Cleaner production of agriculturally valuable benignant materials from industry generated bio-wastes: a review, Bioresour. Technol. 320 (2021) 124281. [37] P. Kumar Sadh, S. Duhan, J. Singh Duhan, Agro-industrial wastes and their utilization using solid state fermentation: a review, Bioresour. Bioprocess. 5 (2018) 1–15.

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[38] S. Dalibor, P. Eva, Sorption of iron, manganese, and copper from aqueous solution using orange peel: optimization, isothermic, kinetic, and thermodynamic studies, Pol. J. Environ. Stud. 26 (2) (2017) 795–800, https://doi.org/10.15244/pjoes/60499. [39] S.A. Ansari, F. Khan, A. Ahmad, Cauliflower leave, an agricultural waste biomass adsorbent, and its application for the removal of MB dye from aqueous solution: equilibrium, kinetics, and thermodynamic studies, Int. J. Anal. Chem. 2016 (2016), https://doi.org/ 10.1155/2016/8252354, 8252354. [40] B.H. Hameed, H. Hakimi, Utilization of durian (Duriozibethinus Murray) peel as low cost sorbent for the removal of acid dye from aqueous solutions, Biochem. Eng. J. 39 (2) (2008) 338–343, https://doi.org/10.1016/j.bej.2007.10.005. [41] Y. Dai, Q. Sun, W. Wang, L. Lu, M. Liu, J. Li, S. Yang, Y. Sun, K. Zhang, J. Xu, W. Zheng, Z. Hu, Y. Yang, Y. Gao, Y. Chen, X. Zhang, F. Gao, Y. Zhang, Utilizations of agricultural waste as adsorbent for the removal of contaminants: a review, Chemosphere 211 (2018) 235–253, https://doi.org/10.1016/j.chemosphere.2018.06.179. [42] G. Islamuddin, M.A. Khalid, S.A. Ahmad, Study of eco-friendly agricultural wastes as non-conventional low cost adsorbents: a review, Ukr. J. Ecol. 9 (2019) 68–75. [43] B.A. Goodman, Utilization of waste straw and husks from rice production: a review, J. Bioresour. Bioprod. 5 (3) (2020) 143–162, https://doi.org/10.1016/j.jobab.2020.07.001. [44] S. Shakoor, A. Nadar, Adsorptive treatment of hazardous methylene blue dye from artificially contaminated water using cucumis sativus peel waste as a low-cost adsorbent, Groundw. Sustain. Dev. 5 (2017) 152–159, https://doi.org/10.1016/j.gsd.2017.06.005. [45] C. Bhattacharjee, S. Dutta, V.K. Saxena, A review on biosorptive removal of dyes and heavy metals from wastewater using watermelon rind as biosorbent, Environ. Adv. 2 (2020), https://doi.org/10.1016/j.envadv.2020.100007, 100007. [46] T. Ahmad, R. Muhammad Aadil, H. Ahmed, U.U. Rahman, B.C.V. Soares, S.L.Q. Souza, T.C. Pimentel, H. Scudino, J.T. Guimara˜es, E.A. Esmerino, M.Q. Freitas, R.B. Almada, S.M.R. Vendramel, M.C. Silva, A.G. Cruz, Treatment and utilization of dairy industrial waste: a review, Trends Food Sci. Technol. 88 (2019) 361–372. [47] F. Asunis, G. De Gioannis, P. Dessı`, M. Isipato, P.N.L. Lens, A. Muntoni, A. Polettini, R. Pomi, A. Rossi, D. Spiga, The dairy biorefinery: Integrating treatment processes for cheese whey valorisation, J. Environ. Manag. 276 (2020) 111240. [48] Solving the E-Waste Problem. Recycling-From E-Waste to Resources: Sustainable Innovation and Technology Transfer Industrial Sector Studies, 2009. [Internet]. Available from: http://www.unep.fr/shared/publications/pdf/DTIx1192xPA-Recycling% 20from%20 ewaste%20to%20Resources.pdf. [49] F. Wang, J. Huisman, C. Meskers, M. Schleup, A. Stevels, C. Hageluken, The best of 2 worlds philosophy: developing local dismantling and global infrastructure network for sustainable E-waste treatment in emerging economies, Waste Manag. 32 (11) (2012) 2134–2146. [50] Basel, Secretariat of the Basel Convention. Where are WEEE in Africa, 2022, [Internet]. Available from: http://www.basel.int/Portals/4/Basel%20Convention/docs/pub/ WhereAreWeeInAfrica_ExecSummary_en.pdf. [51] A.K. Awasthi, X. Zeng, J. Li, Environmental pollution of electronic waste recycling in India: a critical review, Environ. Pollut. 211 (2016) 259–270. [52] W. Foster, U. Azimov, P. Gauthier-Maradei, L. Castro Molano, M. Combrinck, J. Munoz, J.J. Esteves, L. Patino, Waste-to-energy conversion technologies in the UK: processes and barriers—a review, Renew. Sustain. Energy Rev. 135 (2021), 110226. [53] K. Sasiekalaa, R. Malathy, Flexural performance of ferro cement laminates containing silica fume and fly ash reinforced with chicken mesh, Int. J. Civ. Eng. Technol. 3 (2012) 130–143.

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[54] R.R. Chavan, D.D. Kulkarni, Performance of copper slag on strength properties as partial replace of fine aggregate in concrete mix design, Int. J. Adv. Eng. Res. Stud. 2 (4) (2013) 95–98. [55] K. Sasiekala, R. Malathy, Behaviour of mortar containing silica fume and fly ash, J. Ind. Pollut. Control. 28 (2012) 1–7. [56] H. Zhang, H. Wang, X. Zhu, Y.J. Qiu, K. Li, R. Chen, Q. Liao, A review of waste heat recovery technologies towards molten slag in steel industry, Appl. Energy 112 (2013) 956–966. [57] N. Maruoka, T. Mizuochi, H. Purwanto, T. Akiyama, Feasibility study for recovering waste heat in the steelmaking industry using a chemical recuperator feasibility study for recovering waste heat in the steelmaking industry using a chemical recuperator, ISIJ Int. 44 (2004) 257–262. [58] S. Lecompte, S. Lemmens, H. Huisseune, M. Van Den Broek, M. De Paepe, Multiobjective thermo-economic optimization strategy for ORCs applied to subcritical and transcritical cycles for waste heat recovery, Energies 8 (2015) 2714–2741.

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C H A P T E R

2 Exploring brine sludge and fly ash waste for making nontoxic radiation shielding materials Sarika Vermaa,b, Sriparna Paulc, Harsh Bajpaic, Mohd. Akram Khana,b, and Medha Milib,d a

Industrial Waste Utilization, Nano and Biomaterials, CSIR-Advanced Materials and Processes Research Institute (AMPRI), Bhopal, Madhya Pradesh, India, bAcademy of Scientific and Innovative Research (AcSIR), Ghaziabad, India, cCouncil of Scientific and Industrial Research (CSIR)-Advanced Materials and Processes Research Institute (AMPRI), Bhopal, Madhya Pradesh, India, dGreen Engineered Materials and Additive Manufacturing, CSIR-Advanced Materials and Processes Research Institute (AMPRI), Bhopal, Madhya Pradesh, India

2.1 Introduction In today’s modern world, it’s extremely difficult to dispose of the diverse forms of waste generated by various sectors, out of which many of them are nonbiodegradable and are the primary source of environmental contamination in the surrounding community. The rapid rise of industrialization is a notable feature of the substantial environmental damage caused by wastes and toxins generated by companies. Many industries, including the chemical industry, mining industry, steel industry, fertilizer industry, paper and pulp industries, building materials industry, the road construction sector, and many others, have looked into utilization of industrial trash to form a valuable product in recent years. But, within the last few years, the wastes from the chlor-alkali industry, i.e., brine sludge and coal-fired power plants, i.e., fly ash, have come into the highlight in the medical field in the form of radiation shielding material. Radiation was formerly one of the most fundamental components of technical

Advanced Materials from Recycled Waste https://doi.org/10.1016/B978-0-323-85604-1.00017-2

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Copyright © 2023 Elsevier Inc. All rights reserved.

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2. Exploring brine sludge and fly ash waste for making nontoxic radiation shielding materials

advancements. Still, as technology increased, additional health dangers arose, especially radiation as one of the most critical issues to be addressed [1,2]. The term “radiation” refers to a source of energy. This involves generating quick particles and electromagnetic waves by radioactive nuclei, intentionally or spontaneously, to enter stable structures [3]. After the analytics of the electromagnetic spectrum, two different types of radiation are identified based on their energy, namely, ionizing energy (X-Rays and Gamma-rays), and nonionizing energy (radio waves, microwaves, and visible light). Nonionizing energy is low in energy so that atoms in the substance vibrate. In contrast, ionizing radiation is high-intensity radiation that can penetrate a substance and interact with its atoms, causing damage to human health [4]. Radiation plays a vital role in day-to-day activities, from low-energy microwaves to intense gamma rays. Radiation is classified as Natural Radiation and Artificial radiation, i.e., manufactured radiation. Natural radiation cannot be prevented from spreading worldwide despite continual exposure to solar radiation and cosmic rays in the environment. On the other hand, the impact of artificial radiation relies on several parameters, including the radiation type and its energy, the dosage quantity, duration of the exposure, and so on. Cosmic radiation prescribes significant safety problems for missions to space exploration. A broad spectrum of industries, including nuclear power stations, medical/healthcare industry and aerospace, and electronics, are routinely exposed to or encountered with high radiant energy (alpha or beta emissions) and electromagnetic radiation (X-rays or gamma-rays) well as protons particulate matter. Unwanted exposure to such radiation can lead to health risks, such as cell mutation, carcinogenesis, organ disability, heart disease, cataract, and other acute radiation syndromes [5–8]. Radiotherapy is a standard technique for treating cancer patients in medical radiation applications and treating severe diseases. Tissues surrounding the treatment site are typically subjected to penetrating X-rays, affecting internal and surface organ side effects. High-energy X-rays are used in most diagnostic and an operational radiology procedure, such as CT scans. Several electromagnetic devices may lead to radiation exposure at high levels (like X-rays or gamma rays) which emits neutrons and can cause cell mutations, carcinogenesis, and organ failure. The biological tissues are more susceptible to neutron radiation because they allow considerably more dense ions in their active layer. Also, it can produce gamma rays, protons, and alpha particles because of its interactions with biological matter. Therefore, neutron radiation poisoning is more likely in nuclear plant employees and aviators exposed to the radiation [9,10]. Photon attenuation coefficients are of prime importance, which is considered while analyzing X-ray and gamma-ray penetration and diffusion in multielement materials [11]. These coefficients are equivalent to the intensity of the photon incidence and the reactivity of the absorbents.

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2.1 Introduction

Accurate estimates of mass attenuation coefficients of photons in wide and varied substances are vital in economic, environmental, agricultural and medical studies. The coefficients of mass-attenuation can estimate several associated parameters, including bulk permeability of energy, coefficient of molar extinction, sufficient atomic numbers and densities of electrons [12]. The shielding efficiency of some material largely depends upon the radiation type and energy range [11]. Particularly for radiation safety, locations with higher levels of ionizing radiation should be shielded [10,11]. However, few basic notions of protection against radiation, such as shielding, are reliable in all settings. The radiation shielding requirements vary widely depending on the source’s radiation type, activity, and dosage rate. The different radiation types found in spaceships in the form of cosmic radiation which poses significant risks to space exploration efforts, health centers which are associated with low- to-high dose ionizing radiation exposure and can cause cardiovascular consequences, hypertension, stroke and opacities in the lens of the eye [13] and central nervous system [14], and atomic or nuclear reactors that emit X-rays and gamma rays and also tend to emit neutrons are listed in Table 2.1. There are various sources of radiation from the aerospace industry like TABLE 2.1 General overview of radiation sources encountered in three different industries [9]. Industry Aerospace [15]

Radiation sources

Composition

Typical energy range

(i) Cosmic Rays (CR)

The entire flux comprises of high-energy protons (85%), helium nuclei (14%), and heavy nuclei (1%).

(i) 10 MeV–10 GeV

(ii) Solar Particles

Low- to medium-energy protons and alpha particles.

(ii) few MeV–100 s of MeV

(iii) Trapped particles

High-energy electrons and protons.

(iii) electrons: few MeV and protons: several 100 s of MeV

Medical radiology: diagnostic, interventional and radiotherapy [9]

(i) X-rays and γ-rays

Electromagnetic radiation (X-rays and gamma-rays) for therapeutic purposes

Tens of keV–tens of MeV

(ii) Protons and electrons

Neutrons, alpha and beta particles, and γ-rays

Nuclear reactors [9]

(i) Particle emissions

(i) (0–15 MeV) for neutrons, (0–4 MeV) for alpha and beta particles

(ii) γ-rays

(ii) 10 keV to 3 MeV

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2. Exploring brine sludge and fly ash waste for making nontoxic radiation shielding materials

the cosmic rays, solar particles and the trapped particles which comprises of high-energy protons to low-energy protons having its own typical energy range according to its sources. Similarly, from the medical industry, X-rays, gamma-rays, protons and electrons are the sources of radiation having required composition for its particular purposes with different energy ranges. Furthermore, nuclear reactors also have different sources of radiation, i.e., particle emissions and gamma-rays with particular energy ranges. The particular composition and various energy ranges of these industries are mentioned in Table 2.1 in detailed manner. Alpha, beta, neutrons, and electromagnetic waves such as gamma rays are the four primary forms of radiation. Each form of radiation differs in mass, energy, and to what extent it can penetrate people and objects. Alpha particles are highly harmful to human cells while losing their energy quickly, limiting their capacity to permeate materials. Scientists have found various techniques to utilize alpha radiation to their advantage. Typical radioisotopes release beta particles with an energy spectrum ranging from near zero to a maximum. Beta radiation has the same general applications as other types of radiation, such as X-rays. Radiotherapy can be damaging, and the abnormal cells that must be eliminated and the normal cells of neighboring tissue must have distinct sensitivity levels. The radioactive nuclide’s gamma radiations are transmitted as photons, not particles, which means they have no mass or charge. Aside from using nuclear energy to generate power, radioactivity has several applications in a variety of fields. Hence, there is a significant demand for effective, durable radioprotective gear in applications related to potential health hazards from different types of radiation. However, weight and cost are additional aspects to consider while choosing shielding material. Effective shielding causes a significant loss of energy over a short distance without more dangerous radiation. More recently, several radiation protection materials have been created to prevent potentially devastating radiation consequences for individuals and the environment [16–19]. One of the essential factors in finding radiation shielding material with adequate physical qualities is an accurate perception of gamma rays’ interaction with matter. High atomic number and density materials impose a high chance of contact and more significant energy transfer with gamma rays considered a good choice for effective gamma shields. Heavy materials are well-known for their high capacity for gamma-ray attenuation, which is the most critical attribute of a radiation shielding material for radiation protection [17–20]. Several tests and theoretical studies have proven a broad spectrum of protection materials, such as concrete, biopolymer composites, and heavy alloys, all of which have received attenuation or absorption from harmful radiation [13,21,22]. Radiation protection measures may be obtained by putting shielding material directly in and around the wall (e.g., concrete),

2.1 Introduction

31

FIG. 2.1 Types of radiations and its penetration ability. G. Tyagi, A. Singhal, S. Routroy, D. Bhunia, M. Lahoti, Radiation shielding concrete with alternate constituents: an approach to address multiple hazards, J. Hazard. Mater. 404 (2020) 124201.

and wrapping the shielding material around the radiation source is also an alternative option. As illustrated in Fig. 2.1, various radiations have varying penetrating capacities, making them less or more dangerous. Generally, a variety of materials have been utilized to shield against radiation for a variety of purposes. Polyethylene, glasses, epοҳy reᵴin, colemanite, andt lеad were utilized for neutrons and gamma shielding; and, for electrons, lead, lipowitⱬ alloy, and Cu-Ag polymer were used [23]. Furthermore, boron, lead, or compounds were employed to shield properties on concrete composites [24,25]. Dense materials (e.g., lead and z-elements) constitute an essential feature of the radiation shielding material and considerably attenuate gamma rays [17–20]. Lead has been primarily utilized as a radiation shielding material due to its exceptional physical and mechanical properties. Furthermore, there has been an increasing concern recently that lead creates safety and health risks. Lead exposes the employees and patients with insidious threats impacting the body’s metabolic systems [3,6,26,27]. It is, therefore, necessary to replace lead with nontoxic products. Recent studies now focus on developing a radiation shielding material that is nontoxic, lightweight, flexible, and cost-efficient. To design radiation protection systems around nuclear plants, hospitals, health centers, and other industries such as the aero and electronic sectors, researchers are constantly looking for environmentally-friendly radiation protection materials, such as tiles, panels and paver blocks. Tiles

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2. Exploring brine sludge and fly ash waste for making nontoxic radiation shielding materials

are thin plates that are used to cover the surfaces of roofs, floors, and walls. They are primarily composed of clay or any other inorganic raw material. Tiles are now being created from recycled materials, making the aspect more environmentally friendly. The panels are flat or curved, often rectangular, formed or fitted in a door, wall or ceiling surface. Paver blocks are one of the best-known flexible surface treatment alternatives for applications in external paving. These blocks are aesthetical, comfy, highly longlasting and easy to maintain. As a result, radiation shielding tiles, panels, and paver blocks are in high demand for occupations where various forms of radiation pose health risks. However, .industrial waste like brine, sludge and fly ash has not been examined yet for developing radiation shielding materials. In this chapter, a detailed discussion has been provided regarding the brine sludge and fly ash. The benefit of its multielemental properties and its magical effect on the developed nontoxic building materials is discussed in detail. The main aim of this article is to address the feasibility of using. Brine sludge from the chlor-alkali industry and the feasibility of using fly ash from the thermal power plant as a radiation shielding materials by presenting an updated overview of the advancements, treatment strategies, opportunities, and challenges associated with multiple disposal and treatment techniques. This study also serves as a steppingstone for future researchers who wish to develop radiation shielding materials that are cost-effective, easily workable, and ecologically acceptable by utilizing brine sludge and fly ash as raw ingredients. Additionally, this study has also highlighted the superior benefits of the developed nontoxic radiation shielding technologies, which provides excellent radiation protection for a wide range of applications and can be used to solve both waste disposal challenges.

2.2 Brine sludge as radiation shielding materials The brine sludge is the industrial waste formed by the electrolysis of brine in the chloral alkaline industry during chlorine and the caustic soda manufacturing and is usually disposed of in industrial landfills. The chloral alkaline industry is vital to the chemical sector. It produces chlorine, which has many pharmaceuticals, chemicals, ultra-polymers, pure metals, and others [28,29]. Between 2017 and 2022, India’s Chlor-alkali market is expected to rise at a 6.25% compound annual growth rate (CAGR) and is projected to witness robust growth during the forecast period [30]. Fig. 2.2 shows India Caustic Soda Market Size by Region and volume from 2015 to 2030. It’s common for analysts to break down the global Chlor-alkali market into countries, regions and volumes, which helps assess macroeconomic trends. It frequently overlooks some critical

End Products 17

35.45

CI chlorine

Chlorine 1

Chlorine and Caustic

Brine

Salt

by-products

Electrolysis of Brine Water

Unwanted

Soda Production Chlor-Alkali Industry

H

1.01

Hydrogen

Hydrogen

Caustic Soda Stockpiled in

Soil Pollution

FIG. 2.2

Brine Residue

Dams/Rivers

Environment

Disposed to

Brine Sludge

Water Pollution

India caustic soda market size, by region, by volume, 2015–30. H. Wei, Y. Fang, P. Mulligan, W. Chuirazzi, H. Fang, C. Wang, B.R. Ecker, Y. Gao, M. Loi, L. Cao, J. Huang, Sensitive X-ray detectors made of methylammonium lead tribromide perovskite single crystals, Nat. Photonics 10 (2016) 333–339.

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2. Exploring brine sludge and fly ash waste for making nontoxic radiation shielding materials

elements, namely: (1) The global trade environment is determined by the demand for chlorine derivatives and the resulting surplus or deficits of caustic soda, (2) Most Chlor-alkali are produced, bought, sold, and traded by corporations, not countries, and (3) Multinational firms may have different geopolitical aims than the countries where they operate. The need for caustic soda primarily drives the Indian Chlor-alkali industry, and chlorine has been deemed a by-product. Three inorganic chemicals manufactured by the Chlor-alkali industry are caustic soda, chlorine, and soda ash [31]. In India, the soda processing industry is approximately 65 years old, with surplus production volumes and most plants working at an efficiency level of approximately 85%. There are 40 major caustic soda plants with an average capacity of 150 t per day (TPD), which is minor in comparison to developed country plant capacities of 500 t per day (TPD); some in world scale up to 900 t per day (TPD). The GACL-NALCO Alkalies and Chemicals Private Limited (GNAL) Caustic Soda facility is one of the sector’s key projects, with production slated to begin in 2021. The company intends to establish an 800 t per day grassroots Caustic Soda factory in Dahej, which will generate 2.7 lakh tons of Caustic Soda per year approximately. The production of caustic soda is linked to chlorine. Caustic soda and chlorine are manufactured together, whereas soda ash is manufactured separately. This inescapable coproduction has been a source of contention for the chlorine-alkali sector. Both Products are utilized by very distinct end customers and have very different market dynamics, and demand for both coincides on a very rare occasion. Whatever method is utilized to produce chlorine and caustic soda (membrane cells, asbestos diaphragm, or mercury cell), salt is needed as raw material and must be treated before electrolysis, thus generating a considerable volume of brine sludge during the salt treatment process. The most significant environmental issues and challenges confronting this industry relate to brine sludge disposal, which may contain harmful or poisonous compounds that precipitate the brine. Although the sludge waste produced by the chlor-alkali industry is not dangerous, it may contain significant amounts of dissolved metals and other contaminants, which will seep out over time and have a harmful impact on sustainability. Moreover, the sludge produced is harmless, but it might contain considerable levels of toxic metals and other wastedrifting pollutants that damage the ecosystem over time. As a result, it is necessary to develop alternative methods for managing brine sludge to make it appropriate for environmentally safe disposal by stabilizing the leachable impurities. Brine sludge (Fig. 2.3) comprises of multiple elements such as barium (Ba), calcium (Ca), magnesium (Mg), iron (Fe), sodium (Na), together with some additional negligible elements [32,33]. Certain materials, like iron,

35

2.2 Brine sludge as radiation shielding materials

FIG. 2.3

Brine sludge.

titanium, and barium, have a hefty density, providing radiation shielding properties simultaneously. Table 2.2 compiles the physical characteristics of brine sludge, whereas Fig. 2.4 summarizes the chemical properties. These massive amounts of industrial trash will harm the environment and raise transportation costs. As a result, using brine sludge for waste management and environment conservation is highly recommended. The significant environmental issue and challenge is the disposal of these generate waste, brine sludge. It contains a small amount of harmful elements that precipitate from the brine and seep out over time, causing severe damage to the ecosystem. X-ray diffraction (XRD) to analyze the mineralogy of a brine sludge sample and discovered that the bulk of the sludge’s characteristics constituted magnesium hydroxide and calcium carbonate [34]. A comparison was made between the observed TABLE 2.2 The physical parameters of brine sludge and fly ash. Brine sludge S. No.

Fly ash

Properties

[34]

[35]

[34]

[35]

1

Color

Light gray

Light gray

Grayish black

Grayish black

2

Specific gravity

2.63

3

Natural water content (%)

36.21

4

pH

10.55

12

10.5

10.5

5

Physical state at room temperature

Semisolid

Solid

Solid

6

Bulk density, g/cc

2.52

2.35

2.35

36

2. Exploring brine sludge and fly ash waste for making nontoxic radiation shielding materials

CaO MgO SrO SiO2 Fe2O3 Al2O3 Na2O

CHEMICAL COMPOSITION OF FLY ASH

SiO2

Al2O3

Fe2O3

CaO

MgO

SO3

Na2O3

K2O

Cr2O3

ZnO

CuO

LOI

FIG. 2.4 The chemical properties of brine sludge and fly ash.

and reported d values in JCPDS; the analysis revealed the peaks of, CaCO3, Mg(OH)2, NaCl, CaSO4, SiO2, 3Al2O32SiO2 (barium sulfate, BaSO4, JCPDS 24–1035, calcium carbonate, CaCO3, JCPDS 17–763, magnesium hydroxide, Mg (OH)2, JCPDS 7–23, NaCl, sodium chloride, JCPDS 5–628, calcium sulfate, CaSO4 30–279, Q-quartz, syn: silicon oxide, SiO2, JCPDS 46–1045, M-mullite, aluminum silicate, 3Al2O32SiO2, JCPDS 06–0258).

2.4 Applications of brine sludge and fly ash as nontoxic radiation shielding materials

37

2.3 Fly ash as radiation shielding materials Fly ash is a fine powder comprised primarily of solids or porous particles largely crystalline in nature. The five key elements that contribute to fly ash applications are Morphology, texture, chemical structure, and sensitivity, leading to a wide range of practical applications. The carbonate substance is formed of angular particles in fly ash. Fly ash is an environmental pollutant known as fly waste, obtained during pulverized coal combustion in thermoelectric power stations [36]. Much research has been done worldwide in light of the environmental issues presented by fly ash. Fly ash is gaining relevance in many industries, such as manufacturing bricks and ceramics or constructing roads and bridges because of its low cost and availability. Fly ash management is a severe problem in India as a significant part of the total amount of fly ash generated annually remains unutilized. About 500 million tons, of which around 170 million are produced by India alone, are produced worldwide. The chemical composition of coal is determined by the mineral composition of the coal gangue (the inorganic part of the coal), which comprises a variety of elements and compounds [37]. The most common combination is 40%–60% silica and 20%–30% alumina. Iron content varies greatly. The quantity of alkalis is appreciable, and potassium outweighs sodium [12]. According to literature, the relative density of fly ash ranges typically between 2.11and33.0, while its total area of a surface might be between 170 and 1000 m2/kg, according to the literature [38–41]. Other than that, several researchers have stated that the color of coal ash can vary, from tan to gray to black, depending on the amount of unburned carbon present. Table 2.2 represents the physical features of coal ash according to several publications [12,35,42], and Fig. 2.5 represents the chemical components of coal ash. Mass attenuation coefficient μm (cm2/g) for fly ash varies and is depicted in Fig. 2.5A. An increase in μm happens after some level of constancy in the energy range of 2–3 MeV, at which point μm then levels out until a further significant surge is observed by [12].

2.4 Applications of brine sludge and fly ash as nontoxic radiation shielding materials Recycling of brine sludge and fly ash has been the subject of numerous studies, all of which have addressed and assessed different recycling methods. Brine sludge is being investigated as a radiation shielding material in the following ways: Industrial brine sludge waste produces toxic impurities such as calcium, magnesium, and sulfates, which are released

38

2. Exploring brine sludge and fly ash waste for making nontoxic radiation shielding materials

(A)

10kV

(B)

×100 100Pm 0085 AMPR I

(C)

5kV

10kV

×1,000

10Pm 0085 AMPR I

×2,200

10Pm 0085 AMPR I

(D)

×200 100Pm 0085 AMPR I

5kV

FIG. 2.5 SEM images of (A) brine sludge at 100 μm, (B) brine sludge at 10 μm, (C) fly ash at 100 μm, (D) fly ash at 10 μm [43].

into the environment [35,44]. According to Verma et al. [43], the usage of industrial brine sludge waste for the production of unique radiation shielding materials is cost-effective, creative, and inventive; Garg and Pundir [35] developed construction materials using brine sludge, including a mix of cement, coal ash, and brine sludge, concrete pavers, and brick(s). While there are advantages of employing brine sludge in conjunction with fly ash and bonding compound, these two components account for just 35% of the total amount of brine sludge produced; the other 65% of brine sludge remains unutilized. Chen et al. [34] used brine sludge as a substitute for the nonstructural purpose for controlled low strength (CLSM) material, i.e., runny concrete mix. It is worth noting that, like the preceding approach, it also does not utilize modern synthesizing technologies. Therefore, any toxins present in the sludge can leak into the environment, which can cause harmful consequences. However, Verma et al. [45,46] reported a novel process for converting the toxic brine sludge waste into nonhazardous functionalized brine sludge precursor material (FBSPM) which typically contains multiple components and shielding aspects in the optimum morphologies derived from conventional and microwave heating methods, respectively. Initially, brine sludge, fly ash, cetyltrimethylammonium bromide (CTAB), sodium hydroxide, and glycol were synthesized for 2 h at 180°C and then were refluxed in a circular bottom flask via advanced microwave synthesizer set to 45°C for 20 min. With the assistance of a magnetic stirrer, the

2.4 Applications of brine sludge and fly ash as nontoxic radiation shielding materials

39

fluxed materials obtained by both traditional and microwave treatment were separated, filtered, and rinsed twice more with acetone to eliminate any leftover impurities. A functionalized brine sludge precursor material (FBSPM) was prepared to dehydrate this sample at roughly 110°C for 2 h in a hot air oven. The powder was then dissolved in polydimethylsiloxane (PDMS), which produced a customized hybrid inorganic–organic gel, which was then used to fabricate an advanced flexible and moldable X-ray radiation shielding material with the needed dimensions and characteristics. This superior radiation shielding material was investigated for X-ray attenuation qualities with 30 kVp exposure and offered 90% attenuation. Verma et al. [43] made a further improvement because the geopolymerized brine sludge was more effective by speeding up the polymerization process in the sludge-incorporated advance matrix. Furthermore, Verma et al. [33] stated that different polymers had been employed to create radiation shielding materials, such as the polymer composite materials for radiation protection described by [9]. Reference may be made to US patent US2017/0257987A1 to develop and prepare tailored brine sludge, thereby converting the toxic materials to high advanced radiation shielding materials. Firstly, the brine sludge (200–600 g) was dehydrated in an air oven at 100–110°C for 1–2 h, and then it was further heated in a furnace at 800–1300°C for (1 2h). The heated brine sludge so obtained was further mechanochemically processed by grinding with (20–60g) of sodium hexametaphosphate (SHMP) in a ball mill for (1–6) hours, which resulted in the development of customized brine sludge powder. The customized brine sludge powder generated was then compressed in a steel mold using hydraulic pressure in the form of tiles to obtain desired advanced nontoxic radiation shielding materials. Fly ash is being investigated as a radiation shielding material by Singh et al. [12]. They examined the transmission of photon spectrum using fly ash as a shielding medium, considering both primary and secondary radiation components. A direct relationship exists between the attenuation coefficients and the total interaction cross-section of an absorbing material because attenuation coefficients are characteristic attributes of absorbing material. On the other hand, the accumulation factor is a multiplicative factor that incorporates contributions from scattered photons into its calculation. Thus, they are both practical in applying for designing gamma-ray shields. Taking into consideration all prior art and noting the limitations of the existing procedure, the many concerns and problems needing to be resolved for certifying entire utilization of toxic brine sludge for creating advanced, nontoxic radiation shielding materials are listed below: a. Since brine sludge is venomous, its prolonged untreated condition poses a negative impact on the environment. b. Brine sludge can be utilized as a resource material because of its precious chemical compounds such as barium sulfate, magnesium

40

2. Exploring brine sludge and fly ash waste for making nontoxic radiation shielding materials

hydroxide, and calcium carbonate. As a result, brine sludge can be used to produce high-value added products, i.e., advanced nontoxic radiation shielding materials, geopolymer materials, advanced chemically designed composites (ACDC) materials created by embracing the unique properties of chemical compounds naturally occurring in brine sludge. c. Developing value-added superior nontoxic radiation shielding materials by a technology that enables complete usage of toxic brine sludge has the potential to save billions of rupees. d. So far, the brine sludge waste has only been used to produce low-value commodities such as paver blocks and brick materials. However, it is associated with long-term environmental risks. Therefore, in light of the shortcomings of the previously disclosed patent application, the developers of this innovation have established that advanced nontoxic radiation protection materials using brine sludge is urgently necessary. Thus, it is clear that brine sludge and fly ash will protect persons and the environment from potentially disastrous radiation and can be utilized to develop radiation shielding materials with these two industrial by-products waste. Ceramic tiles or nonporcelain tiles and Porcelain tiles are the two types of tiles in building construction based on material and manufacture. Radiation shielding ceramic tiles and Radiation shielding porcelain tiles can be prepared and developed (Fig. 2.6) [10].

FIG. 2.6

Advanced nontoxic radiation shielding valuable materials for broad application spectrum. Modified and retrieved from G. Tyagi, A. Singhal, S. Routroy, D. Bhunia, M. Lahoti, Radiation shielding concrete with alternate constituents: an approach to address multiple hazards, J. Hazard. Mater. 404 (2020) 124201.

2.6 Future perspectives

41

2.5 Conclusion From the literature mentioned above, it can be concluded that the brine sludge and fly ash have multielemental properties and can be beautifully converted into different products that benefit society, especially in the healthcare sectors, nontoxic radiation shielding materials. Several researchers like Verma et al. [43], Garg and Pundir [35], and Shukla et al. [47] concluded that brine sludge could be utilized as a nontoxic radiation shielding material after being chemically treated and can be used as a nonrenewable resource to make construction materials such as paver blocks, tiles, mortars, and bricks can be partially replaced with brine sludge instead of Portland cement [35,43,47]. The sludge samples can be used as a chemically reactive binder, i.e., silica and aluminum react with Ca2+ to generate calcium silicates and aluminates that solidify the entire bulk [48]. In addition, the presence of magnesium oxide in brine sludge can reduce shrinkage strain in cementitious materials, improving their structural strength and durability. An additional benefit of incorporating these leftovers into building material is that any poisonous heavy metals present will be neutralized in the matrix. Singh et al. [12] concluded that just like concrete, fly ash can be employed as a protective substance if it is compressed to a large extent, which in this case is indeed conceivable. Thus, it is possible to approach the novelty method with the help of chemical treatment and ceramic treatment for treating brine sludge and fly ash to develop various forms of radiation shielding materials in the shape of panels and tiles. As a result, hazardous industrial waste such as brine sludge and fly ash can minimize waste, contributing to sustainability, circular economy, and waste reduction efforts. Fly ash and brine sludge are appropriate resources for developing multilayered and multiphased advanced nontoxic radiation shielding material.

2.6 Future perspectives According to the research reviewed above, both brine sludge and fly ash have different benefits in the production of nontoxic radiation shielding materials because of the presence of multielemental and multicomponent phases which can be chemically treated and ceramically treated. It will aid in the development of different types of nontoxic radiation shielding materials in various shapes such as paver blocks, tiles, and panels, among other applications. Besides, these materials can be used in healthcare applications such as X-ray rooms and CT scanner rooms and to construct structures that house nuclear materials, such as nuclear power plants, radiology laboratories, atomic energy research institutions, and particle accelerators.

42

2. Exploring brine sludge and fly ash waste for making nontoxic radiation shielding materials

Furthermore, the quality, strength, and safety of these nontoxic radiation shielding materials can be increased by incorporating various forms of industrial waste into the developed structural and nonstructural building elements by reinforcing it after proper chemical treatment and optimization. Some examples of these industrial wastes are red mud, brine sludge, fly ash, various types of plastic waste, and also the PPE waste which are generated during the pandemic times. Therefore, it is possible to generate nontoxic radiation shielding materials from heavy metal wastes with multielemental qualities, which can improve the strength and durability of newly designed structural and nonstructural elements.

References [1] I. Akkurt, C. Basyigit, S. Kilincarslan, B. Mavi, A. Akkurt, Radiation shielding of concretes containing different aggregates, Cem. Concr. Compos. 28 (2) (2006) 153–157. [2] I. Akkurt, S. Kilincarslan, C. Basyigit, The photon attenuation coefficients of barite, marble and limra, Ann. Nucl. Energy 31 (2004) 577–582. [3] M. Ogawa, Y. Nakajima, R. Kubota, Y. Endo, Two cases of acute lead poisoning due to occupational exposure to lead, Clin. Toxicol. 46 (4) (2008) 332–335. [4] I. Akkurt, A.M. El-Khayatt, The effect of barite proportion on neutron and gamma-ray shielding, Ann. Nucl. Energy 51 (2013) 59. [5] S.A. Abo-El-Enein, F.I. El-Hosiny, S.M.A. El-Gamal, M.S. Amin, D.M. Ramadan, Gamma radiation shielding, fire resistance and physicochemical characteristics of Portland cement pastes modified with synthesized Fe2O3 and ZnO nanoparticles, Constr. Build. Mater. 173 (2018) 687–706. [6] N.J. AbuAlRoos, N.A.B. Amin, R. Zainon, Conventional and new lead-free radiation shielding materials for radiation protection in nuclear medicine: a review, Radiat. Phys. Chem. 165 (2019), 108439. [7] F.A. Cucinotta, Y.M. Kim, L. Ren, Radiat. Meas. 41 (2006) 1173–1185. [8] N. Lobato, E. Villegas, M. Mansur, Management of solid wastes from steelmaking and galvanizing processes: a brief review, Resour. Conserv. Recycl. 102 (2015) 49–57. [9] S. Nambiar, J.T.W. Yeow, Polymer-composite materials for radiation protection, ACS Appl. Mater. Interfaces 4 (2012) 5717. [10] G. Tyagi, A. Singhal, S. Routroy, D. Bhunia, M. Lahoti, Radiation shielding concrete with alternate constituents: an approach to address multiple hazards, J. Hazard. Mater. 404 (2020), 124201. [11] M. Erdem, O. Baykara, M. Do
gru, F. Kulu€ ozt€ urk, Radiat. Phys. Chem. 79 (2010) 917–922. [12] K. Singh, C. Singh, G.S. Sidhu, J. Singh, P.S. Singh, G.S. Mudahar, Flyash: a radiation shielding material Ind, J. Phys. 77A (2003) 41–45. [13] D.Y. Stewart, P.F. Harrison, B. Morgan, Y. Ramachers, Nucl. Inst. Methods Phys. Res. A 571 (2007) 651–662. [14] C. Belka, W. Budach, R.D. Kortmann, M. Bamberg, Radiation induced CNS toxicity– molecular and cellular mechanisms, Br. J. Cancer 85 (9) (2001) 1233–1239. [15] S. Sen, E. Schofield, J.S. O’Dell, L. Deka, S. Pillay, JOM 61 (2009) 23–31. [16] B. Oto, et al., Investigation of gamma radiation shielding properties of various ores, Prog. Nucl. Energy 85 (11) (2015) 391–403, https://doi.org/10.1016/j.pnucene.2015.07.016. [17] V.P. Singh, N.M. Badiger, J. Kaewkhao, Radiation shielding competence of silicate and borate heavy metal oxide glasses: comparative study, J. Non-Cryst. Solids 404 (11) (2014) 167–173, https://doi.org/10.1016/j.jnoncrysol.2014.08.003. Elsevier B.V.

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[42] Z. Giergiczny, Effect of some additives on the reactions in fly ash–Ca(OH)2 system, J. Therm. Anal. Calorim. 76 (2004) 747–754. [43] S. Verma, S.S. Amritphale, M.A. Khan, Utilization of brine sludge and fly ash waste as complementary resources, for making non-toxic, geopolymeric (cement-free) materials, Iran. J. Sci. Technol., Trans. Civ. Eng. 43 (1) (2019) 603–614. [44] E. Masilela, L. Lerotholi, T. Seodigeng, H. Rutto, The dissolution kinetics of industrial brine sludge wastes from a chlor-alkali industry as a sorbent for wet flue gas desulfurization (FGD), J. Air Waste Manage. Assoc. 68 (2) (2018) 93–99. [45] S. Verma, S. Amritphale, S. Das, J. Mater. Eng. Perform. 26 (2017) 1018. [46] S. Verma, S. Amritphale, M.A. Khan, A. Anshul, S. Das, J. Polym. Environ. 25 (2017) 999. [47] P.M. Shukla, J.A. Patel, D.S. Joshi, P.P. Joshi, Recovery of barium sulphate from brine sludge, Indian J. Environ. Prot. 352 (2) (2015) 312–315. [48] T. Gonc¸alves, R.V. Silva, J. De Brito, J.M. Ferna´ndez, A.R. Esquinas, Hydration of reactive MgO as partial cement replacement and its influence on the macroperformance of cementitious mortars, Adv. Mater. Sci. Eng. 2019 (2019), 9271507.

C H A P T E R

3 Use of red mud as advanced soil stabilization material Suchita Rai, Sneha Bahadure, M.J. Chaddha, and A. Agnihotri Jawaharlal Nehru Aluminium Research Development and Design Centre (JNARDDC), Nagpur, Maharashtra, India

3.1 Introduction In Bayer’s process, to produce alumina, the bauxite ore is digested with sodium hydroxide solution at high temperature and pressure. The by-product which remains after the extraction of alumina is known as “red mud” or “bauxite residue” [1]. A massive quantity of about 150 million tons of red mud is generated globally every year [2]. China alone contributed to more than half of the total red mud generation while India maintained fourth place generating approximately 9 million tons per year [3]. The red mud generation scenario is quite alarming and has become an environmental problem in the aluminum industry as handling, storage and disposal become a challenge due to its alkaline nature. Red mud derives its color and name from its iron oxide content. Red mud is a blend of un-extracted material present in the bauxite and compounds formed during the Bayer process. Red mud has high alkalinity (pH 12–13) and is very fine in size (d50 < 10 μm) [4]. Its chemical composition and mineralogy depend upon the technology adopted for alumina extraction and the origin of bauxite. For centuries red mud has been considered as waste and disposed of in landfills after thickening or filtration [5]. There is always a possibility of contamination of groundwater due to alkali seepage and a large land area is required for its storage. During summer, the wind carries the fine red mud particles which impact plant life due to the deposition of alkaline dust on them. Also, there is a big possibility of environmental disasters being caused due to the failure of these large volume pond’s

Advanced Materials from Recycled Waste https://doi.org/10.1016/B978-0-323-85604-1.00016-0

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Copyright © 2023 Elsevier Inc. All rights reserved.

46

3. Use of red mud as advanced soil stabilization material

containment structure [6]. Ajka, Hungary, is the worst example of this since 10 people lost their lives, while more than 100 people have been seriously injured due to red mud release from the pond [7]. Though there is a need for improvement in the storage and disposal practices of red mud, utilization of red mud can contribute well in solving the concern of red mud. This may include application areas such as building and construction [8], recovery of valuables [9], absorption of pollutants [10], catalyst and catalyst support [11], paints and pigments [12] and vegetation [13]. Red mud can be added to contaminated soil to improve its value. Research toward the utilization of red mud in soil remediation has been started after the year 2000. Toward this, the proposed chapter is an overview of the application of red mud in immobilization in agricultural soil, remediation of heavily contaminated acidic soils, and fly ash stabilization for its use as embankment material in road construction. It also gives a brief overview of the chemical composition and physical properties of red mud, investigations carried out worldwide, and their findings in the application of red mud as a soil stabilizer.

3.2 Chemical properties of red mud The composition of red mud varies from region to region due to the origin of bauxite and refining conditions. Typical red mud consists of iron as Fe2O3 (30%–60%), alumina as Al2O3 (10%–20%), silica as SiO2 (3%–50%), titania as TiO2 (traces-25%), soda as Na2O (2%–10%) and lime as CaO (2%– 8%) [14] (Pontikes). Indian red mud can be classified into high Fe2O3, moderate TiO2 and medium Fe2O3 and high TiO2 depending on the bauxite processed. The typical composition of Indian red mud is shown in Table 3.1 [8]. Red mud consists of trace elements such as Cu, Zn, V, Ni, Co, Cr, P, Pb, Cd, Mn, Mg, Ga and Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Yb, and Lu as rare earth elements (all in ppm). TABLE 3.1 Typical composition of red mud in India. Constituents

%

Al2O3

16–23

Fe2O3

40–62

SiO2

4.5–9.5

TiO2

4–16

CaO

0.5–3

Na2O

3–6.5

LOI

8.5–13

47

3.4 Red mud as a soil stabilizer

3.3 Physical properties of soil and red mud Soil is the natural mineral present abundantly on the earth surface and is a necessity for living organisms. Soils are variable according to their physical and chemical characteristics such as particle size distribution, bulk density, particle density, soil permeability, moisture content, pH of the soil, humic content, COD and BOD, etc. both on the surface (horizontally) as well as vertically. The properties of the soil will result in the distribution of the water and other minerals. Red mud has a specific surface area of 14–23 m2/g with a real density of 3.1–3.8 g/cm3. Some of the engineering properties of Indian soil and red mud are given in Table 3.2 [15,16]. Due to the chemical as well as physical properties of red mud it becomes necessary to investigate the effects of red mud on soil’s unconfined compressive strength, hydraulic conductivity, and swelling percentage. Red mud can be blended with various additives like cement, clay, compost gypsum/its derivatives. Studies show that the application of red mud with additives is effective in deactivating the heavy metals of soil without affecting vegetation and crop quality.

3.4 Red mud as a soil stabilizer Soil contaminated with metals (Cd, Zn, Pb, Ni, Cu, As), acids, etc. can badly impact the quality of crops, plant growth rate and quality of groundwater. Reduction of heavy metal content is necessary to avoid leaching as TABLE 3.2 Engineering properties of Indian soil and red mud. Properties

Soil

Red mud

Grain size (μm)

–

0.7–100

Specific gravity, G

2.67

2.7

Maximum dry density (MDD) (g/cc)

1.52

1.712

Optimum moisture content (OMC) (%)

23

30.5

Cohesion (kPa)

18

12.25

Angle of internal friction (in degree)

12

26.8

California Bearing Ratio (CBR)

3.1

3.368

Permeability, k (cm/sec)

–

5.7832  10

7

S. Sridevi, S. Sahoo, S. Sen, Stabilization of expansive soil with red mud and lime, in: Ground Improvement Techniques and Geosynthetics, 2019, pp. 259–268; P. Pandey, Soil remediation using red mud and fly ash, GJESR, 1(12) (2015).

48

3. Use of red mud as advanced soil stabilization material

well as bioavailability of these toxic metals into the soil. This is done by various methods like adsorption, stabilization by addition of additives to form insoluble complexes, ion exchange method and surface precipitation. Soil stabilization is one of the effective methods of deactivating/ reducing these heavy metals. Additives are added to the soil to make these pollutants biologically inactive and immobile. These heavy metals are not completely removed but are reduced and deactivated. Stabilization of trace metals from contaminated soil is an effective remediation technique in which immobilizing agents are used to reducing the metal mobility in the soil. The method works on the principle that the trace metals/contaminants are physically bound within a stabilized mass, or chemical reactions are taking place between the immobilizing agent and trace metals to reduce their mobility [17]. Soil stabilization is not a new technique but a well-known phenomenon in traditional agriculture. Organic matter (compost, humus) and inorganic matter (lime, phosphates) are used to improve the fertility of the soil by reducing mobility and bioavailability of toxic elements [18]. Due to industrialization, the soil is contaminated through industrial activities such as mining, landfilling, smelting, tailings, and many more. To reduce the spreading of toxic elements, present in these sites to nearby agricultural land, deactivation of these elements is required. Many researchers have suggested soil stabilization followed by vegetation to maintain an esthetic environment contributing to the ecosystem [19–21]. Industrial by-products can be used to balance the properties of the soil. Fly ash is a majorly used industrial by-product in soil stabilization and road construction [22]. Paper industry by-products, lime sludge are other examples of such stabilization products. Red mud by-products from the aluminum industry have been found to have the ability to remediate the contaminated soil by lowering the metal content and pH. From one of the studies, red mud (3%–5%) and lime both are found to be equally effective in removing heavy metals like Pb, Cu, zinc, nickel, cadmium and intensifying the re-vegetation in bare soil. The plant growth and bacteria inside the soil do not get affected in the presence of red mud and this treatment is proven to be the cost-saving method for removing heavy metals from soil [23]. Limestone, red mud and furnace slag are used as immobilizing agents to the soil in 2%–5% for deactivation of heavy metal pollutants [24]. The polluted soil and marine sediments containing heavy metals such as Cd, Ni, Zn and Pb were treated by red mud/apatite composites. The decrease in heavy metal percentages for Pb, Cd, Zn, Ni is up to is 11.9%, 6.8%, 2.8%, and 24.7% respectively [25]. Hungarian red mud (2%–5%) having pH 9 was used as a stabilizer to treat two different soil samples taken from mine waste and agricultural land. The effect on Cd and Zn content in contaminated soil, microbes present in the soil, and pH reduction before and after treatment was studied.

3.5 Discussion

49

Results have shown that though the contamination does not remove, immobilization has taken place successfully. Metals are found to remain in the soil but become completely chemically, biochemically inactive and non-transportable. Also, the red mud present in the soil does not harm the plant and microbes present in the soil [6]. Red mud was added to the soil in 5–30 weight % and properties such as maximum dry density (MDD), optimum moisture content (OMC), California bearing ratio (CBR), unconfined compression (UCC) were studied. Red mud (15%) gave the best results. Red mud treated with lime (2%) was found to be more effective in replacing 20% of soil [26]. The strength of black cotton soil has been improved by using 10%–40% red mud. Red mud (30%) was found to be effective in increasing the UCS and CBR value as a further increase in red mud decreases the strength [27]. Expansive soil is the major hurdle in the construction because of its high water absorption ability increasing its volume which is more enough to damage the building structure. Modified red mud with 4% lime and modified fly ash were used as soil stabilizers in the range of 10 to 50%. From the results, it was observed that the dry density increases with the decrease in shear parameter and cohesion after red mud addition. Red mud and fly ash mixture is used as a stabilizer with the significant effect in an improvement in the compaction characteristics, limit to the plasticity index, and water limit [15]. Fig 3.1 shows the overview of stabilization of various kinds of soils using red mud which can then be used for various applications. Investigators all over the world researched to study the applicability of red mud for the reduction of soil contamination shown in Table 3.3.

3.5 Discussion Red mud is found to be capable to stabilize various types of soils such as soil contaminated with industrial additives and soil contaminated with sewage sludge, soil near zinc smelter and heavy sludge, grassland, lead extract soil, brownfield soil, black cotton soil, agricultural soil contaminated with wastewater, expansive soil, clay, tailing polluted farmland soil, soil from gold mine area, etc. Unstabilized as well as stabilized red mud can be used to remediate the contaminated soil. Gypsum, fly ash, cement, lime calcium sulfate is used to stabilize red mud and can be used further. Moderate to high changes from 4.6 to 9.4 are observed in the pH of soil by using red mud in the range of 2%–5%. The amount of metal/metalloid in contaminated soil has been decreased by red mud stabilization which can be seen in Table 3.3. Improvement of compressive strength by 79% was observed by using 50% red mud in clay. The physical properties of soil have also been improved by using red mud as a soil stabilizer. Maximum

50

3. Use of red mud as advanced soil stabilization material

FIG. 3.1 Soil stabilization using red mud.

dry density (MDD) is improved by 6%–10%. California Bearing ratio (CBR) has also been found to increase by up to 55%. Unified compressive strength has also been improved by using red mud soil stabilizer.

3.6 Conclusion Contributing to solving the problem of red mud storage and disposal, soil stabilization can play a vital role. It can help in minimizing the quantity of red mud stockpiled every year while providing the advantage of stabilizing contaminated soil. In this era of urbanization, where agricultural land is the need of people, red mud can help by reducing the contaminants from soil and make it fertile. Also, more studies are required to conduct to study the effect of red mud on plant growth at the field level. Various species should be studied for their growth on red mud stabilized soil. This will enable bulk consumption of red mud by making its use in soil stabilization which can minimize the problem of red mud to quite an extent. Internationally, in Europe, demonstration on the use of processed/

TABLE 3.3 Application of red mud as a soil stabilizer.

Soil source

Properties of the soil before stabilization (mg/kg)

Stabilizer used

Source of red mud

Red mud quantity used

Properties of soil after treatment (mg/kg)

References

Agricultural soil

pH 6.9; As: 122; Cd: 8.9; Pb: 440 Zn: 1601

Red mud

Hungary

2%–5%

pH 7–7.2; As: 50–62; Cd: 7.9–8.81; Pb: 250–374 Zn: 928–1248

[6]

Expansive soil

MDD:15.2 kN/m3 Cohesion:47 kN/m2 Friction: 20°

Lime stabilized red mud

India

10%–50%

MDD: 16.3 kN/m3 Cohesion:47 kN/m2 Friction: 24°

[15]

Brown-field site

pH 4.7; Cd: 79; Cu: 311; Ni:36 Pb: 4210; Zn: 3970

Lime, phosphorous, red mud

UK

3%–5%

pH 5.6; Cd: 38–65.57; Cu: 22–53; Ni:15–30; Pb: 741–1894; Zn: 992–2302

[23]

Clay soil

MDD:16.4 kN/m3

Lime, Red mud

India

5%–30%

MDD:17.4 kN/m3 Improved unified compressive strength and CBR value

[26]

Black cotton soil

–

Red mud, sodium silicate

India

10%–40%

Improved unified compressive strength and CBR value

[27]

Lead and Zinc mine extract soil

pH: 5.9; Cd: 92; Cu: 64; Pb: 5022 Zn 18,532

Red mud

USA

2%–11%

pH: 7.3; Cd: 65.32; Cu:57.856; Pb: 2661.66; Zn: 4262

[28]

Continued

TABLE 3.3 Application of red mud as a soil stabilizer—cont’d

Soil source

Properties of the soil before stabilization (mg/kg)

Clay

–

Red mud and cement

Turkey

5%–50%

Improvement of compressive strength by 79%

[29]

Heavy metal contaminated soil

pH:4.23; Pb: 3266; Cd: 35.4; Zn: 1495

Red mud, zeolite and lime

Italy

4%

pH:7.11; Pb: 3271; Cd: 35.9 Zn: 1454

[30]

Soil near Pb/Zn smelter

pH 4.9; Cd: 5.6; Pb: 913; Zn:545

Red mud

Austria

1%

pH 5.7; Cd: 0.56; Pb: 91.3 Zn:65.4

[31]

Gold mine area

pH 4.6; As: 20.0; Cd: 2.5; Pb: 117 Zn:233

Red mud

Korea

2%–5%

pH 8.1–9.4; As: 6.4–14.2; Cd: 0.275; Pb: 1.17–8.19; Zn: 2.33

[32]

Tailing polluted farmland

pH 4.6; Pb: 817; Zn:614

Red mud

China

1%–5%

pH 5.9–6.8; Pb: 294–539 Zn: 202–233.32

[33]

Agricultural land

Cd: 0.89

Red mud

China

0.5%–1%

Cd: 0.79

[34]

Agricultural soil contaminated with wastewater irrigation

pH 5.4–5.5; Cd: 0.89–13 Pb: 608; Zn:882

Red mud

China

0.5%– 30%

pH: 7.6; Cd: 0.77–11.57; Pb: 6.08; Zn: 26.46

[35]

Stabilizer used

Source of red mud

Red mud quantity used

Properties of soil after treatment (mg/kg)

References

Natural Soil

MDD:18.14 kN/m3; CBR:5.42%

Red mud

India

4%–24%

MDD:18.92 kN/m3 CBR:12.28%

[36]

Soil contaminated with industrial additives (French) and sewage sludge (UK)

pH: 5.5/6.4; Cd: 19/42; Cr: 31/156; Cu: 78/145; Pb: 842/230; Zn: 2920/1756

Beringite, red mud

Hungary

2%

Improved properties of soil

[37]

Zinc smelter (French) heavy sludge (UK)

pH: 5.5/6.4; Cd: 19/42; Cu: 78/145; Zn: 2920/1756

Lime, beringite, and red mud

Hungary

5%

pH: 7.3/6.8; Cd: 5.0/8.9; Zn: 530/402

[38]

Grassland

pH: 4.6; As: 4772; Cu: 1058

Red mud

UK

2%

pH: 5.7; As: 3435; Cu: 232.76

[39]

54

3. Use of red mud as advanced soil stabilization material

treated red mud with other industrial byproducts as a green soil stabilizer for civil works application has been reported. The study is in the phase of pilot plant development. In India, the work in this arena has gained momentum since the year 2012, but still, there is a need to do extensive research on red mud as a soil stabilizer which has a future potential of its bulk utilization. Only lab-scale studies have been conducted till now. Contaminated soil sites should be identified in the area nearby to red mud storage pond and trials should be taken to amend this soil using red mud. The amended soil can be utilized in the land filling, embankment, road construction, etc. This will ultimately help in taking steps toward eco-friendly production of aluminum metal, the need of future.

References [1] A. Akinci, R. Artir, Characterization of trace elements and radionuclides and their risk assessment in red mud, Mater. Charact. 59 (2008) 417–421. [2] K. Evans, The history, challenges and new developments in the management and use of bauxite residue, J. Sustain. Metall. (2016) 316–331. [3] S. Xue, Y. Wu, Y. Li, W. Kong, F. Zhu, H. William, X. Li, Y. Ye, Industrial wastes applications for alkalinity regulation in bauxite residue: a comprehensive review, J. Cent. South Univ. 26 (2019) 268–288. [4] S. Rai, S. Bahadure, M. Chaddha, A. Agnihotri, Disposal practises and utilization of red mud (bauxite residue): a review in Indian context and abroad, J. Sustain. Metall. 6 (1) (2020) 1–8. [5] G. Power, M. Grafe, C. Klauber, Bauxite residue issues: I. Current management, disposal and storage practices, Hydrometallurgy 108 (2011) 33–45. [6] W. Feigl, A. Viktoria, U.N. Attila, G. Ketalin, Red mud as a chemical stabilizer for soil contaminated with toxic metals, Water Air Soil Pollut. 223 (3) (2012) 1237–1247. [7] S. Ruyters, J. Mertens, E. Vassilieva, B. Dehandschutter, A. Proffijn, E. Smolders, The red mud accident in Ajka (Hungary): plant toxicity and trace metal bioavailability in red mud contaminated soil, Environ. Sci. Technol. 45 (2011) 1616–1622. [8] S. Rai, S. Bahadure, M. Chaddha, A. Agnihotri, A way forward in waste management of red mud/bauxite residue in building and construction industry, Trans. Indian Natl. Acad. Eng. 5 (2020) 437–448. [9] Y. Liu, R. Naidu, Hidden values in bauxite residue (red mud): recovery of metals, Waste Manag. 34 (12) (2014) 2662–2673. [10] A. Bhatnagar, V. Vilar, C. Botelho, R. Boaventura, A review of the use of red mud as adsorbent for the removal of toxic pollutants from water and wastewater, Environ. Technol. 32 (3–4) (2011) 231–249. [11] S. Sushil, V. Batra, Catalytic applications of red mud, an aluminium industry waste: a review, Appl. Catal. B Environ. 81 (1–2) (2008) 64–77. [12] J. Pera, R. Boumaza, J. Ambroise, Development of pozzolanic pigment from red mud, Cem. Concr. Res. 27 (10) (1997) 1513–1522. [13] S. Rai, M. Chaddha, A. Agnihotri, Potential applications of red mud in vegetation, in: Proceedings of National Conference on Waste to Wealth and Metallurgical Industries, Bhubaneswar, India, 2018. [14] Y. Pontikes, Red Mud Project, 2005. www.redmud.ord/Characteristics.html. (Accessed 2 April 2019).

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[15] S. Sridevi, S. Sahoo, S. Sen, Stabilization of expansive soil with red mud and lime, in: T. Thyagaraj (Ed.), Ground Improvement Techniques and Geosynthetics, Springer Nature, Singapore, 2019, pp. 259–268. [16] P. Pandey, Soil remediation using red mud and fly ash, GJESR 1 (12) (2015). [17] Federal Remediation Technology Roundtable (FRTR), Remediation Technologies Screening Matrix and Reference Guide. Version 4.0. USA, 2002. https://frtr.gov/ matrix2/section4/4-21.html. (Accessed 2 April 2021). [18] N. Bolan, D. Adriano, D. Curtin, Soil acidification and liming interactions with nutrient and heavy metal transformation and bioavailability, Adv. Agron. 78 (2003) 215–272. [19] G. Tordoff, A. Baker, A. Willis, Current approaches to the revegetation and reclamation of metalliferous mine wastes, Chemosphere 41 (1–2) (2000) 219–228. [20] S. Seoane, M. Leiros, Acidification–neutralisation in a linite mine spoil amended with fly ash or limestone, J. Environ. Qual. 30 (4) (2001) 1420–1431. [21] P. Bleeker, A. Assuncao, P. Teiga, T. de Koe, J. Verkleij, Revegetation of the acidic, As contaminated Jales mine spoil tips using a combination of spoil amendments and tolerant grasses, Sci. Total Environ. 300 (2002) 1–13. [22] D. Dermatas, X. Meng, Utilization of fly ash for stabilization/solidification of heavy metal contaminated soils, Eng. Geol. 70 (3–4) (2003) 377–394. [23] S. Lee, J. Lee, Y. Choi, J. Kim, In situ stabilization of cadmium-, lead-, and zinccontaminated soil using various amendments, Chemosphere 77 (8) (2009) 1069–1075. [24] W. Shin, Y. Kim, Stabilization of heavy metal contaminated marine sediments with red mud and apatite composite, J. Soils Sediments 16 (2014) 726–735. [25] C. Gray, S. Dunham, P. Dennis, F. Zhao, S. McGrath, Field evaluation of in situ remediation of a heavy metal contaminated soil using lime and red mud, Environ. Pollut. 142 (3) (2006) 530–539. [26] M. Aswathy, S. Unnikrishnan, V. Gayathri, Utility of lime and red mud in clay soil stabilization, J. Geotech. Geoenviron. Eng. 1 (2016) 19–26. [27] N. Mane, M.S. Rajshekhar, Stabilization of black cotton soil by using red mud and sodium silicate, Int. Res. J. Eng. Technol. 4 (7) (2017). [28] S. Brown, B. Christensen, E. Lombi, M. McLaughlin, S. McGrath, J. Colpaert, J. Vangronsveld, An inter laboratory study to test the ability of amendments to reduce the availability of Cd, Pb and Zn in situ, Environ. Pollut. 138 (2005) 34–45. [29] E. Kalkan, Utilization of red mud as a stabilization material for the preparation of clay liners, Eng. Geol. 87 (3) (2006) 220–229. [30] G. Garau, C. Paola, S. Laura, D. Pietrino, M. Pietro, Influence of red mud, zeolite and lime on heavy metal immobilization, culturable heterotrophic microbial populations and enzyme activities in a contaminated soil, Geoderma 142 (1–2) (2007) 47–57. [31] W. Friesl, K. Platzer, O. Horak, M. Gerzabek, Immobilising of Cd, Pb, and Zn contaminated arable soil close to a former Pb/Zn smelter: a field study in Austria over 5 years, Environ. Geochem. Health 31 (2009) 581–594. [32] S. Lee, E. Kim, H. Park, J. Yun, J. Kim, In situ stabilization of arsenic and metalcontaminated agricultural soil using industrial by-products, Geoderma 166 (2011) 1–7. [33] Y. Huang, X. Hao, Effect of red mud addition on the on the fractionation and bioaccessibility of Pb, Zn, and As in combined contaminated soil, Chem. Ecol. 28 (2012) 37–48. [34] R. Feng, W. Qiu, F. Lian, Z. Yu, Y. Yang, Z. Song, Field evaluation of in situ remediation of Cd-contaminated soil using four additives, two foliar fertilizers and two varieties of palchoi, J. Environ. Manag. 124 (2013) 17–24. [35] P. Pavel, E. Diacu, C. Barbu, Long term effects on the fractionation and mobility of heavy metals in a polluted soil treated with bauxite residues, Rev. Chim. 66 (2015) 13–16. [36] D. Singh, P. Kushwaha, J. Thomas, A. Padlak, Improvement of soil sub grade by using red mud for flexible payment, IJIRTM 4 (1) (2020) 87–95.

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[37] E. Lombi, F. Zhao, G. Zhang, B. Sun, W. Fitz, H. Zhang, S. McGrath, In situ fixation of metals in soils using bauxite residue: chemical assessment, Environ. Pollut. 118 (3) (2002) 435–443. [38] E. Lombi, R. Hamon, S. McGrath, M. McLaughlin, Lability of Cd, Cu and Zn in polluted soils treated with lime, Beringite and red mud and identification of a non-labile colloidal fraction of metals using isotropic techniques, Environ. Sci. Technol. 37 (5) (2003) 979–984. [39] E. Lombi, R. Hamon, G. Wieshammer, M. McLaughlin, S. McGrath, Assessment of the use of industrial by-products to remediate a copper and arsenic-contaminated soil, J. Environ. Qual. 33 (2004) 902–910.

C H A P T E R

4 Conversion of agricultural crop waste into valuable chemicals Vrushali H. Jadhava, Chetana R. Patilb, and Sanjay P. Kambleb a

Catalysis and Inorganic Chemistry Division, CSIR-National Chemical Laboratory, Pune, India, bChemical Engineering and Process Development Division, CSIR-National Chemical Laboratory, Pune, Maharashtra, India

4.1 Introduction Fossil fuels are nothing but coal, oil, and natural gas obtained from natural resources. They are formed by the anaerobic decomposition of dead remains of plants and animals. This process takes millions of years. Today, most of the energy we use is derived from these fossil fuels. Due to depletion and limited stock of the fossil fuels, the world will be in a crunch of energy resources. Hence, there is a need to have an alternative energy resource like solar energy, wind energy, biomass, etc. Biomass is one of the sustainable resources available today in abundance. Biomass is nothing but organic matter that is derived from plants. The plants get chemical energy from the Sun by a process of photosynthesis, and this energy gets stored in the plants. Biomass is generally burnt directly for producing heat; however, it emits CO2 in the atmosphere which leads to global warming. Biomass has a huge potential to be used in the production of biofuels and various value-added chemicals [1]. There are two types of biomass used for the synthesis of fuels or chemicals, the first one is food crop and second one is nonfood crop. The food crops such as sugarcane, corn, grains (barley, wheat, and rye), etc., are used for the production of bio-ethanol which is used as a fuel additive and also as a solvent in chemical industry. These food crops are required for human consumption as well as for the synthesis of various fuels and chemicals. Hence, there is

Advanced Materials from Recycled Waste https://doi.org/10.1016/B978-0-323-85604-1.00015-9

57

Copyright © 2023 Elsevier Inc. All rights reserved.

58

4. Conversion of agricultural crop waste into valuable chemicals

a competition for the food crops for its use. Therefore, viable alternative is to produce fuels/chemicals from nonfood crops or agricultural crop waste. When a crop is grown, it undergoes several processes such as harvesting, processing, and storage. After the crop is harvested, the waste generated during this process is called as agricultural crop waste [2]. The agricultural crop waste is considered to have great potential as a renewable resource for synthesis of biofuels and valuable chemicals. In India, generally, most of the agricultural crop waste produced is either burnt or dumped. Due to this, tremendous air pollution occurs by increasing the levels of carbon dioxide and carbon monoxide in the atmosphere. The major crops grown globally are rice, corn, wheat, barley, sugarcane, etc., and a tremendous amount of waste is generated from these plants (Fig. 4.1). The rice grains are covered with hard protective covering which is known as rice husk. It is separated from the grains during rice milling process. The rice husk is removed from the grain to get whole brown rice; further milling of the bran layer is removed to get the white rice. The rice husks amount to nearly 20% of the rice produced. Rice straw, wheat and barley straw, and corn stover are the dry stalks of rice, wheat, barley, or corn plants, respectively, after the grain has been removed. Corn cob is generally used as an animal feed or as a fertilizer all over the world. Corncob being a renewable raw material, it is looked to have great potential for producing number of valuable chemicals such as ethanol, sugars, citric acid, lactic acid, etc. Sugarcane bagasse is nothing but the dry fibrous matter that remains after crushing sugarcane. The agricultural waste generated from these crops is majorly produced from agricultural countries such as India,

Wood Pellet

Rice Husk

Wood Chips

Palm Waste

Straw

Sugar Cane Waste

Short Rotation Crop

Bio waste

FIG. 4.1 Sources of agricultural waste. Copyright from R. Singh, A. Shukla, A review on methods of flue gas cleaning from combustion of biomass, Renew. Sustain. Energy Rev. 29 (2014) 854–864.

4.1 Introduction

59

China, Southeast Asia, USA, and Brazil. Each type of crop waste contains different constituents in different proportions. These agricultural crop wastes are mainly made up of cellulose (40%–50%), hemicellulose (25%–35%), and lignin (15%–20%). Other than these small quantities of silica, ash and waxes are also found in this waste. Proper utilization of agricultural wastes as raw materials will help to reduce the dependency on fossil fuels and also reduce the pollution and production cost of fuels and chemicals derived from it. Lignin forms the outer cell wall of biomass. Cellulose is surrounded by hemicellulose and lignin functioning as a matrix respectively. Hemicellulose provides linkage and binds together lignin and cellulose. Plant cell wall consists of cellulose as a major component of its structure. As shown in Fig. 4.2, cellulose is a polysaccharide made up of glucose monomers (50–1500) that are linked to each other with β-1,4-glycosidic linkages [3]. Due to the β-1,4 orientation of the glycosidic bonds there is an intermolecular and intramolecular hydrogen bonding which makes native cellulose highly crystalline and insoluble in most of the solvent. It is also found to be resistant to enzymatic hydrolysis. Hemicellulose is a branched polymer made up of five membered sugars such as D-xylose, L-arabinose and six membered sugars such as D-rhamnose, D-galactose, and D-mannose with 50–200 units. Lignin is a cross linked aromatic polymer [4]. The aromatic monomers are mainly trans-p-coumaryl alcohols, trans-sinapyl, and trans-coniferyl. Lignin is covalently bound to hemicelluloses, forming a complex matrix that surrounds the cellulose micro-fibrils. The CdC and CdOdC linkages in the lignin give structural rigidity and protection to the plant. Other than lignin, tannins and phenolic acids are also found in plant cell walls. Tannins are high molecular weight (500–3000) polyphenolic compounds, composed of hydroxyflavans, leucoanthocyanidin (flavan3,4-diol), and catechin (flavan-3-ol) or glucose. Phenolic acids are structural components of the lignin core in plant cell wall. Pectin’s are also found in the plant cell wall and make up to approximately 35% of the primary cell walls and mainly contain galactosyluronic residues. Proteins too are found in minor amount in plant cell wall and are covalently cross-linked with lignin and other polysaccharides. The components of the lignocellulose can be separated using different pretreatment methods. Physical method includes mechanical comminution (chipping, milling, and/or grinding) irradiation with various radiations, pyrolysis, etc. Physicochemical pretreatment includes, steam explosion, ammonia fiber explosion (AFEX), carbon dioxide explosion, etc. Chemical method includes acid hydrolysis, base hydrolysis, ozonolysis, oxidative delignification, organosolv process, or oxidizing reagents. Biochemical method involves treatment of lignocellulose with various enzymes [5].

FIG. 4.2 Major constituents of lignocellulose. From J. Baruah, B.K. Nath, R. Sharma, S. Kumar, R.C. Deka, D.C. Baruah, E. Kalita, Recent trends in the pretreatment of lignocellulosic biomass for value-added products, Front. Energy Res. 6 (2018) 141.

61

4.2 Value-added chemicals from lignocellulosic biomass

The strategy mainly used for conversion of lignocellulose is gasification, pyrolysis, and hydrolysis [6]. Gasification method converts lignocellulose to syngas whereas using pyrolysis, bio-oil is formed. Generally, the fuels that are directly obtained from lignocellulosic biomass using gasification and pyrolysis are of low quality as it contains high content of oxygenates and water. Hence, there is a need to carry out further process like hydrodeoxygenation, aromatization, Fischer–Tropsch synthesis, and water gas shift reaction to reduce the oxygenated contains and obtain biofuel of good quality. Acid-catalyzed hydrolysis of lignocellulose is more difficult compared to gasification and pyrolysis. Gasification and pyrolysis are one step process for lignocellulose conversion to biofuels, whereas acid-catalyzed hydrolysis of lignocellulose is more than one step process. As the quality of biofuel obtained by acid-catalyzed process is good, this method is more promising and useful. Hydrolysis of cellulose and hemicellulose will produce C5–C6 sugars which can further be converted to platform chemicals such as furfural, 5-hydroxymethylfurfural, levulinic acid, etc. In 2004, the US Environmental Energy had identified top 12 value-added platform chemicals that can be used as building blocks in synthesis of various industrially important chemicals. These are 1,4succinic acid, fumaric acid, maleic acids, 2,5-furan-dicarboxylic acid, 3-hydroxy propionic acid, aspartic acid, glucaric acid, glutamic acid, itaconic acid, levulinic acid, 3-hydroxybutyrolactone, glycerol, sorbitol, and xylitol/arabinitol. In this chapter, we have discussed various industrially important chemicals that can be derived from agricultural crop-waste. In order to get an overview of these chemicals, various methods of their synthesis from petrochemicals as well as from bio-based resources and its applications of industrially important chemicals, has been described in this chapter.

4.2 Value-added chemicals from lignocellulosic biomass 4.2.1 Furfural Furfural is one of the important chemical that can be obtained from agricultural residues, such as corncob, rice husk, and sugarcane bagasse (SCB) or wood residues as shown in Fig. 4.3. OH OH

O

OH

HO O

O

HO

OH

O

O

H

+

O HO

O O

HO HO

OH

+H2O

O

OH OH

OH

H+

O

–H2O

OH

Hemicellulose

FIG. 4.3

Xylose

Production of furfural from lignocellulosic waste [7].

Furfural

62

4. Conversion of agricultural crop waste into valuable chemicals

The furfural market size is projected to grow from USD 551 million in 2019 to USD 700 million by 2024, at a compound annual growth rate (CAGR) of 4.9%, during the forecast period. Additionally, the market is projected to reach 423,372 tons by 2024, at a CAGR of 4.5% during the forecast period. Synthesis of furfural from 1,3-diene which can be obtained from fossil resources which is not very attractive and hence furfural is not generally produced from fossil fuels. Furfural was first commercially produced in 1922 by a company called Quaker Oats. Corn residue is the promising biowaste which can be converted to furfural using mineral acid H2SO4. Furfural can be obtained from renewable resources by acid catalyzed reaction of C-5 sugars from lignocellulose [8]. Table 4.1 shows literature available on acid catalyzed furfural production. As shown in Fig. 4.4, furfural serves as a platform molecule for synthesis of various industrially important chemicals. Alonso et al. reported 96% yield of furfural from corncob using 0.025 M H2SO4 in presence of biphasic solvent GVL/H2O at 170 °C in 30 min [7]. Bagasse as a substrate produces 66.3% yield of furfural in presence of TABLE 4.1 Literature reports on dehydration of lignocellulosic biomass to furfural. Time (min)

Furfural yield (%)

References

170 90% GVL-H2O

30

96

[7]

0.4 M HCl

THF-H2O (2:1)

200

20

66.3

[9]

Corncob

0.10 wt% H2SO4

H2O

190

20

99.5

[10]

4

Bagasse

HUSY

H2O/ p-xylene

170

360

56

[11]

5

Xylose

H2SO4

GVL

175

–

75

[12]

6

Xylose

H-mordenite

GVL-10% H2O

175

120

80

[13]

7

Xylose

HCl, NaCl

H2O

200

–

81.3

[14]

8

Xylose

H-beta

GVL-10% H2O

160

60

71

[15]

9

Xylose

0.05 M H2SO4 MIBK

170

20

80

[16]

10

Xylan

Al2(SO4)3

GVL-H2O 130

30

87.8

[17]

2-MTHF/ 160 H2O

90

77.35

[18]

S. no. Substrate Catalyst

Solvent

1

Corn stover

0.025 M H2SO4

2

Bagasse

3

11

Xylan

2

NaCl-SO4 / SnMMT

Temp. (°C)

4.2 Value-added chemicals from lignocellulosic biomass

FIG. 4.4

63

Chemicals derived from furfural [8].

0.4 M HCl using THF-H2O solvent system at 200 °C for 20 min [9]. Li et al. also achieved 99.5% yield of furfural from corncob using 10 wt% H2SO4 as catalyst and H2O solvent at 190 °C in 20 min [10]. Sahu et al. studied HUSY catalyst for furfural production using bagasse, it yields 56% of furfural in 360 min at 170 °C [11]. Xylose in presence of H2SO4 forms 75% yield at 175 °C [12]. Dumesic and coworkers used H-mordenite for conversion of xylose and obtained good yield 80% for furfural in presence of GVLH2O solvent system at 175 °C in 120 min [13]. Xylose in presence of HCl gives 81.3% yield of furfural at 200 °C using H2O as solvent [14]. Gallo et al. used H-beta catalyst for synthesis of xylose to furfural in presence of GVL-H2O solvent which yields 71% of furfural in 60 min at 160 °C [15]. Xylose to furfural conversion using biphasic reaction was studied by Mittal et al. using MIBK and 0.05 M H2SO4 producing 80% yield of furfural at 170 °C in 20 min [16]. Researchers also used use pure hemicellulose such as xylan as starting materials for the production of furfural. Yang et al. studied the Al2(SO4)3 catalyst for conversion of xylan to furfural giving 87.8% furfural yield at 130 °C in 30 min in presence of GVL-H2O solvent system [17]. Sun and coworkers used SO24 /Sn-MMT solid acid catalyst for furfural synthesis from xylan at 160 °C in 90 min in presence of 2-MTHF/H2O as solvent which yields 77.35% of furfural [18]. The process of converting lignocellulosic biomass to furfural has some major drawbacks such as low yields and formation of side products with

64

4. Conversion of agricultural crop waste into valuable chemicals

humin. There are on-going efforts for developing new technologies for synthesis of furfural from lignocelluloses in an economical and environmentally sustainable way.

4.2.2 Furfuryl alcohol Furfuryl alcohol has large number of applications in chemical industry. It is an important building block used in chemical as well as pharmaceutical industry. Industrially furfuryl alcohol is produced by liquid phase or gas phase hydrogenation of furfural using Cu–Cr catalyst. Due to use of toxic metals in production it causes serious environmental concerns. Hence metals other than chromium such as Pd, Pt, Ru, Ni, Co, and Cu are studied for furfural hydrogenation both in gas phase and liquid phase. Sixty-five percent of furfural is consumed for production of furfuryl alcohol. Furfuryl alcohol is mainly used for synthesis of resins. It is also used for synthesis of polyethylene foams and poly ester. It also acts as a solvent for making phenolic resins. The chemicals that can be synthesized from furfuryl alcohol are shown in Fig. 4.5. Dihydropyran is prepared by Achmatowicz reaction, reaction of furfuryl alcohol using Br2 in MeOH [19]. Tetrahydrofurfuryl alcohol is synthesized by hydrogenation of C]C in the furan ring. It is used as an aircraft fuel, as a solvent and intermediate in synthesis of various chemicals [20]. 2-Methylfuran is considered to be an alternative fuel and is prepared by hydrogenolysis of furfuryl alcohol [21]. Furfuryl acetate is prepared by esterification of furfuryl alcohol by using acidic catalyst [22].

FIG. 4.5 Furfuryl alcohol to industrially important chemicals.

4.2 Value-added chemicals from lignocellulosic biomass

FIG. 4.6

65

Synthesis of furan by bio-based route and its applications.

4.2.3 Furan Furan is commercially produced by palladium-catalyzed decarbonylation of furfural (Fig. 4.6). It is mainly used as a raw material for the synthesis of various chemicals. Tetrahydrofuran (THF) is a versatile solvent and used as a precursor to polymers. Annually, around 200,000 tons of tetrahydrofuran is produced [23]. The commercial process uses acid-catalyzed dehydration of 1,4butanediol. THF can also be synthesized by hydrogenation of furan [24]. This method is under study and lot of research is carried out to develop a process for hydrogenation of furan to THF. Thiophene is another important chemical that can be derived from furan. Annual production of thiophene is around 200 metric tons per year. It is produced by vapor phase reaction of sulfur source with butane. Thiophene is a very important chemical as it can be used in polymer industry. It is also an important building block in pharmaceuticals and agrochemicals [25]. Pyrrole is prepared by treating furan with ammonia in presence of SiO2/Al2O3 solid acid catalyst at high temperature [26]. Pyrrole is also an important chemical and has applications in the synthesis of many drug molecules.

4.2.4 2(5H)-furanone 2(5H)-furanone is mainly used as an intermediate in the synthesis of natural products and surfactants. Presently 2(5H)-furanone is produced by the oxidation of furfural using hydrogen peroxide as an oxidant. 2(5H)-furanone is mainly used as a platform chemical for the synthesis of important chemicals γ-butyrolactone (GBL) and 1,4-butanediol. GBL is industrially produced by copper-catalyzed dehydrogenation of 1,4-butanediol at high temperature. GBL is a precursor to chemicals such as N-methyl-2-pyrrolidine and pyrrolidone. It is also used as a solvent and in polymers. 1,4-Butanediol is required on a scale of 1 million metric tons per year globally. It is used mainly as a solvent and in manufacture of polyurethanes, fibers, and plastic.

66

4. Conversion of agricultural crop waste into valuable chemicals

4.2.5 Levulinic acid Levulinic acid is an important platform chemical. It can be produced from cellulose/starch/glucose/fructose by dehydration reaction as shown in Fig. 4.7. Table 4.2 displays literature reports available for production of LA [27]. Alipour et al. studied LA synthesis from second generation biomass, i.e., corncob using [BMIMSO3H] HSO4 as catalyst in aqueous media at 95 °C in 1 h, results 70% yield for LA [28]. Homogeneous catalyst SnCl4 was also reported for corncob conversion which yields 64.6% of LA in presence of water at in 1 h [29]. Cellulose in presence of Amberlyst 70 at 160 °C yields 69% of LA in GVL/H2O solvent system [30]. Xiang et al. showed highest yield 91% of LA from cellulose using Ni modified ETS-10 zeolite in aqueous media at 200 °C in 6 h [31]. Pyo et al. studied cellulose conversion to LA over ZrO2 in presence of H2O at 180 °C for 3 h gives 39% yield toward LA [32]. Heeres and coworkers studied sulfuric acid-catalyzed conversion of glucose and fructose to LA in water yields 70.7% (at 145 °C) and 74.6% (at 110 °C) LA respectively in 24 h [27]. Fructose in presence of H2SO4 yields 74% of LA in aqueous media at 140 °C [33]. Garces et al. studied 0.25 M HCl to produce LA from hexoses yields 51% and 83% of LA from glucose and fructose dehydration at 130 °C [34]. Chang and coworkers used sulfonated graphene oxide for LA synthesis from glucose at 200 °C in 2 h it gives 50% LA yield [35]. Glucose dehydration using CrCl3 + HY zeolite hybrid catalyst gave 40% LA yield in 3 h at 160 °C [36]. Liu et al. studied [HO3S-(CH2)3-mim] Cl-FeCl3 ionic liquid for LA production from cellobiose yields 67.51% LA at 180 °C in 10 h [37]. Commercial production of levulinic acid is carried out from fructose using mineral acids at high temperature and high pressure. Many important chemicals such methyl levulinate, γ-valerolactone (GVL), valeric

OH

OH

OH

OH

OH

O HO HO

O HO O

O

OH OH

+

H

O HO

O

OH OH

HO

+H2O

n

OH

Cellulose

OH

Glucose H+ –H2O

O

O OH O

Levulinic acid

H+ +H2O

O

OH

5-Hydroxymethyl furfural (5-HMF)

FIG. 4.7 Acid-catalyzed conversion of cellulose to levulinic acid [27].

67

4.2 Value-added chemicals from lignocellulosic biomass

TABLE 4.2 Literature reports on levulinic acid production.

Catalyst

Temp. Solvent (°C)

Time (h)

Levulinic acid yield (%)

References

Corn stover

[BMIMSO3H] HSO4

H2O

95

1

70

[28]

2.

Corncob

SnCl4

H2O

180

1

64.6

[29]

3.

Cellulose

Amberlyst 70

GVL/ H2 O

160

16

69

[30]

4.

Cellulose

0.5 g Ni-HMETS-10

H2 O

200

6

91

[31]

5.

Cellulose

ZrO2

H2O

180

3

39

[32]

6.

Glucose Fructose

H2SO4/NaCl

H2O

145 110

24 24

70.7 74.6

[33]

7.

Fructose

H2SO4

H2O

140

0.5

74

[34]

8.

Glucose Fructose

0.25 M HCl

H2O

130

4

51 83

[35]

9.

Glucose

Sulfonated graphene oxide

H2 O

200

2

50

[36]

10.

Glucose

CrCl3 + HY zeolite hybrid catalyst

H2O

160

3

40

[37]

11.

Cellobiose [HO3S-(CH2)3-mim] Cl-FeCl3

H2O

180

10

67.51

[38]

S. no. Substrate 1.

ester, pentanoic acid, methyltetrahydrofuran, and δ-aminolevulinic acid (DALA) can be synthesized from levulinic acid. Whereas chemicals such as pentenoic acid, 1,4-pentanediol, and methylenevalerolactone can be synthesized form GVL. Methyl levulinate can be used for blending in biodiesel. 2-Methyl tetrahydrofuran (MTHF) prepared from levulinic acid can be used in P-series type fuel as it blends with gasoline without modification in the engine. Levulinic acid can be converted to n-octane by electrochemical method. It forms valeric ester which is used as a gasoline additive. Levulinic acid is also converted to GVL which is an important platform chemical for biodiesel and fuel additives, polymer industry, aromatics such as benzene, toluene, and xylene [38].

4.2.6 Caprolactam Caprolactam is another very important chemical that is used in nylon industry, paint industry, plastic industry, for synthesis of polyurethanes [39]. Nylon has market size 4.6 billion tons globally. Caprolactam was first

68

4. Conversion of agricultural crop waste into valuable chemicals

prepared by cyclization of ε-aminocaproic acid. Caprolactam can also be synthesized by various methods from raw materials such as cyclohexanone, cyclohexanol, and cyclohexane produced from bio-based sources. As shown in Fig. 4.8, bio-renewable route includes synthesis of caprolactam using 6-aminocaproic acid. 6-Amino caproic acid is obtained by fermentation of sugars [40]. Caprolactam can be obtained from lysine. Lysine is obtained by fermentation of glucose. Caprolactam can also be synthesized from 1,3-butadiene which in turn can be obtained from bioethanol. Caprolactam can also be produced from muconic acid which in turn can be derived from glucose. Muconic acid is converted to adipic acid under hydrogenation which in turn is converted to caprolactam under hydrogenation condition. Another bio-source from which caprolactam can be obtained is from 5-hydroxymethylfurfural and levulinic acid. 5-HMF can be synthesized from fructose, glucose by dehydration whereas levulinic acid can be synthesized by acid hydrolysis of cellulose or hemicellulose via furfural or HMF.

4.2.7 Cyclopentanone Cyclopentanone and 3-hydroxymethylcyclopentanone are important chemicals as they are used for resins, high-density biofuels, lubricating oils, lysine, and vitamins [41]. The global market at present for cyclopentanone is around 100 million USD. Cyclopentanone is commercially produced from fossil fuel based adipic acid whereas there is no commercial

FIG. 4.8 Synthesis of caprolactam by bio-based routes and its applications in various industries.

4.2 Value-added chemicals from lignocellulosic biomass

69

process available for synthesis of 3-hydroxymethylcyclopentanone. Cyclopentanone can also be synthesized from bio-based furfural using multiple steps such as hydrogenation, furan ring rearrangement, hydrogenation, and dehydration (Fig. 4.9) [42]. Cyclopentanone is used in the synthesis of diesel fuels such as cyclic alkanes [43]. It can also be used for synthesis of cyclopentylamine, caprolactone, caprolactam, tercyclopentane, pentanedoic acid, and diesel range C-15 cyclic alkanes.

4.2.8 1,3-Propane diol It is an important chemical in chemical industry. The global market is expected to reach USD 690 million by 2025. 1,3-Propane diol is used in production of polytrimethylene terephthalate, polyurethane, cleaning products, personal care and cosmetics, engine coolants, food beverages, heat transfer fluids, polyester resins, etc. (Fig. 4.10). It will be a replacement for fossil-based chemicals such as glycerin, propylene glycol, butylene glycol, etc., which are currently used in cosmetics, personal care products, food and pharmaceutical industry. 1,3-Propane diol can be produced from ethylene oxide in two steps. In the first step, ethylene oxide and carbon monoxide are reacted using suitable catalyst and desired reaction condition gives hydroxyl aldehyde which on further reduction gives 1,3-propane diol. It can also be produced from acrolein which in turn is produced from petroleum-based propylene. This is a two-step process, in first step, addition of water to acrolein forms 3-hydroxypropionaldehyde followed by catalytic hydrogenation to give 1,3-propane diol. 1,3-Propane diol is produced from glycerol too; glycerol is the side product of biodiesel industry [44]. Acrolein can also be prepared from bio-based resource glycerol, which can be

FIG. 4.9

Synthesis of cyclopentanone by bio-based route and its applications.

70

FIG. 4.10

4. Conversion of agricultural crop waste into valuable chemicals

Synthesis of 1,3-propane diol by bio-based routes and its applications.

obtained either by fermentation method or by selective deoxygenation using chemical catalysis. 1,3-Propanediol can also be synthesized from renewable resource glucose. A commercial scale process is available for the synthesis of 1,3-propane diol using fermentation of glucose [45]. The propane diol produced from bio-resources has lower impurities compared to that produced from fossil resources.

4.2.9 Ethylene glycol Ethylene glycol is a very important chemical industrially and it has mainly two major applications. Its global market is around 300 million USD. It is used as a raw material for the synthesis of polyester polyethylene terephthalate used in plastic industry and used for antifreeze formulations [46]. On industrial scale ethylene glycol is produced from fossil fuel based ethylene via ethylene oxide using acidic or basic catalyst. It can also be produced commercially using ethylene and carbon dioxide to form ethylene carbonate. Alternatively ethylene glycol is produced from carbon monoxide in countries having large reserves of coal. Ethylene glycol can also be produced from biomass based sugars by fermentation route [47]. Sugars are fermented to ethanol which is then converted to ethylene and subsequently to ethylene glycol using petrochemical route (Fig. 4.11). It can also be produced by another route of pyrolysis of sugars to mixed

FIG. 4.11

Synthesis of ethylene glycol by bio-based routes and its applications.

4.2 Value-added chemicals from lignocellulosic biomass

71

oxygenates which are further hydrogenated to ethylene glycol along with formation of propylene glycol. Production of ethylene glycol from biobased resources such as glucose or cellulose is a challenge as demand of ethylene glycol is increasing as it serves as a monomer for making bio-based plastic [48].

4.2.10 Gamma-valerolactone GVL is recently identified as an industrially important chemical. GVL is polar with high boiling point and found to be an excellent solvent for converting lignocellulosic biomass into important chemicals and fuels [49]. Under hydrogenation conditions levulinic acid can be converted to GVL efficiently [50]. It can also be obtained from furfural via furfuryl alcohol (Fig. 4.12) [51]. GVL itself can be used as a fuel additive but there are certain limitations for using it due to its solubility in water, low energy density and blending limits. GVL serves as an important platform molecule and can be converted to methyl tetrahydrofuran MTHF under hydrogenation conditions [52]. MTHF has potential to be used as a liquid fuel. Aromatic hydrocarbons can be synthesized from GVL using thermal deoxygenation that can be used as fuel additives. Pentanoic acid is another important chemical that can be derived from GVL [53]. Pentanoic acid can further be deoxygenated and oligomerized to form C8 alkanes which is in the range of jet fuels. GVL can be converted to valeric acid which can be further esterified to form valeric ester that can be used as biodiesel and fuel additive. Valeric acid can also be deoxygenated and oligomerized to form C9 alkanes which can be used as gasoline, diesel fuels. C18–C27 alkanes that are used as diesel fuels can also be derived from GVL via valeric acid. GVL is also used as a green solvent. Due to its herbal odor finds applications in perfume and food industry.

FIG. 4.12

Synthesis of GVL by bio-based route and its applications.

72

FIG. 4.13

4. Conversion of agricultural crop waste into valuable chemicals

Synthesis of maleic anhydride by bio-based route and its applications.

4.2.11 Maleic acid and maleic anhydride Maleic acid and maleic anhydride are one of industrial important chemicals. The global market for maleic anhydride is around 3.0 billion USD. Presently commercial process available for production of maleic acid and maleic anhydride is from petroleum feedstock. Maleic anhydride is commercially produced either by oxidation of benzene or vapor phase oxidation of butane. The route from butane is more preferred due to environmental reason and it’s more economical. Maleic acid is produced by hydrolysis of maleic anhydride. Due to depleting fossil resources there is a need to produce maleic acid and maleic anhydride from renewable resources [54]. Furfural is bio-based platform chemical obtained from lignocellulose which can be converted to maleic acid and anhydride as shown in Fig. 4.13. Furfural can be oxidized using air, O2 or H2O2 to maleic anhydride under catalytic conditions [55]. Further, maleic acid and maleic anhydride can be converted to important chemicals such as 1,4-butanediol, γ-butyrolactone, tetrahydrofuran, N-methylpyrrolidine, 1,4-diaminobutane, succinamide, and succinate esters. These chemicals find wide applications in various sectors such as polyester resin, surface coatings, lubricants, plastics, fragrances, pharmaceuticals, and agrochemicals.

4.2.12 Isosorbide Isosorbide is a bicyclic fused furan ring having two hydroxyl functionalities. It is an important chemical and has global market of nearly 350 million USD. Isosorbide is industrially obtained by catalytic dehydration of sorbitol (Fig. 4.14) [56].

4.2 Value-added chemicals from lignocellulosic biomass

FIG. 4.14

73

Synthesis of isosorbide by bio-based route and its applications.

Sorbitol can be produced by hydrogenation of D-glucose which in turn can be obtained from starch or cellulose. Isosorbide and its derivatives are important chemicals as they have wide utility. Looking at the increasing use of isosorbide, there is a need to increase the production of isosorbide. For industrial application, it is a challenge to increase the yield of isosorbide so that process is economically viable [57,58]. Diester of isosorbide is used as a commercial plasticizer for PVC and as surfactants. Dimethylisosorbide is used as a solvent in cosmetic industry whereas dinitroisosorbide is used as a vasodilator for decades. Due to the diols present in isosorbide and also due to its rigid structure it has wide applications in polymer industry. They are used as monomers for industrial production of polycarbonate, polyester, polyurethane, polyamides, epoxy resin, etc.

4.2.13 Acrylic acid Acrylic acid is a very important chemical as it can serve as a raw material for number of industrially important chemicals (Fig. 4.15). Its global market is around 13 billion USD. Commercially acrylic acid is produced by partial oxidation of propylene. Propylene is obtained from petroleum resources as it is a by-product of ethylene and gasoline production. Alternative route for the production of acrylic acid is selective oxidation of propane, however this route generate huge of amount of waste

74

FIG. 4.15

4. Conversion of agricultural crop waste into valuable chemicals

Synthesis of acrylic acid by bio-based route and its applications.

and also due to depletion of these fossil resources there is a need for production of acrylic acid from renewable resources. Alternative method is available to obtain acrylic acid from renewable resources is fermentation of 3-hydroxypropionic acid and its dehydration to produce acrylic acid [59]. Another route for the production of acrylic acid is by oxydehydration of glycerol [60]. Glycerol is a by-product of biodiesel process. Glycerol is dehydrated to 3-hydroxypropanol subsequently acidic treatment produces acrolein which is further oxidized to form acrylic acid. Conversion of carbohydrates to lactic acid by fermentation and dehydration of lactic acid to acrylic acid is another important route for its production [61]. Another alternative route is conversion of sugars to 1,2-propylene glycol and dehydration of propylene glycol to allyl alcohol which on oxidation gives acrylic acid [62]. Acrylic acid has main application as super adsorbent polymers and detergent polymers. Super adsorbent polymers have the ability to absorb and retain 100 times more liquid of its weight. They are mainly used in diapers. Super adsorbent polymers also have application in food packaging. Acrylic acid is also used in textile and water treatment industry. Acrylic acid and its di-ester combine with self or other monomers such as acrylamide, acrylonitrile to form polymers that are used in polishes, paints, elastomers, plastic, adhesives, coatings, resins, etc.

4.2.14 1,5-Pentane diol 1,5-Pentanediol is an industrially important chemical [63]. The global market for 1,5-pentanediol is around 600 ktons. 1,5-Pentanediol is produced currently as a by-product in the synthesis of caprolactam. During synthesis of caprolactam from cyclohexane, glucaric acid is produced as one of the by-product. Glucaric acid is further hydrogenation gives 1,5pentanediol. It can also be produced from biomass feedstock. Hydrolysis of hemicellulose gives C5-sugars which can be converted to 1,5pentanediol via furfural (Fig. 4.16).

4.2 Value-added chemicals from lignocellulosic biomass

75

An industrial scale process for the production of furfural is currently available from C-5 sugars that can be obtained from corn cobs, corn stover, bagasse, etc. The furfural can then be hydrogenated to 1,5-pentanediol with 85% yield [64,65]. 1,5-Pentanediol has wide applications, e.g., when 1,5-pentane diol reacted with adipic acid forms polyester polyols. When it reacts with 2,5-furandicarboxylic acid it forms renewable resin. Polycarbonate polyols are used in adhesives, coatings, polyurethane dispersion. Polycarbonate polyols are superior to polyester and polyether and are greener. 1,5-Pentanediol is a replacement for fossil based 1,6-hexane diol with reduced cost and enhanced properties for polyesters and polycarbonate polyols.

4.2.15 2,5-Furandicarboxylic acid (FDCA) FDCA is a very important monomer and it was identified as one of top 12 value-added chemical by US Department of Energy. The global market for FDCA is expected to be 850 million USD by 2025. It is an alternative to petroleum derived terephthalic acid. Terephthalic acid and ethylene glycol reacts to form polyethylene terephthalate which is used as a plastic in today’s world. FDCA can be derived from renewable resources. It is reacted with ethylene glycol to form bio-based plastic, i.e., polyethylene furanoate [66]. Bio-based polymers such as polyurethanes, polyesters and polyamides can be synthesized from FDCA. FDCA is obtained from cellulose/glucose/fructose which can be derived from lignocellulose either using chemical, biological or electrochemical method [67]. The C-6 sugars obtained from lignocellulosic biomass can be dehydrated to form 5-hydroxymethylfurfural (5-HMF) which in turn undergoes oxidation to form 2,5-furandicarboxylic acid as shown in Fig. 4.17 [68]. Table 4.3 shows various reports available on catalytic oxidation of HMF to FDCA. Several noble metals like Pt, Pd, Au, Ru supported on different supports found efficient to oxidize HMF and producing good yield for FDCA [68–77]. Zhang et al. developed MnCo2O4 spinel catalyst for synthesis of FDCA from HMF gives 70.9% yield of FDCA in 24 h at 100 °C in presence of 20 bar oxygen [78]. Industrially FDCA is produced from fructose using homogeneous catalyst but this process has some drawbacks. Looking at the demand of FDCA in future there is a challenge to develop an efficient and cost effective process for production of FDCA.

FIG. 4.16

Synthesis of 1,5-pentanediol by bio-based route and its applications.

76

4. Conversion of agricultural crop waste into valuable chemicals O O

2,5-diformyl furan (DFF)

O O

OH

O

O

O

O O

OH

O

2

2

5-Hydroxymethyl furfural (5-HMF)

5-formyl-2-furan carboxylic acid (FFCA)

O O HO

O

OH

2

5-Hydroxymethyl-2-furan carboxylic acid (HFCA)

O

O O

HO

OH

2,5– Furandicarboxylic acid (FDCA) FIG. 4.17

Oxidation of 5-HMF to FDCA and DFF.

4.2.16 2,5-Diformyl furan (DFF) It is also an important chemical as it has applications in polymer industry. 2,5-DFF can be synthesized by selective oxidation of hydroxyl groups in 5-hydroxymethylfurfural to aldehydic functionality [79]. DFF can be used to produce furan based chemicals, surfactants, vitrimers and fluorescent material. An efficient and economical process for the production of DFF from bio-resources still remains a challenge on industrial scale mainly due to cost and safety issues [80]. More efforts are needed to produce DFF from glucose or even cellulose rather than fructose, which will reduce its cost. Green solvent and use of less toxic reagents is also important in order to avoid any environmental harm.

4.2.17 Furoic acid 2-Furoic acid is an important chemical that is used as a preservative acting as fungicide/bactericide and flavoring agent in food industry. It is also used in nylon preparation and optic technologies. Currently, 2-furoic acid is industrially obtained by Cannizaro’s reaction, i.e., reacting furfural with NaOH. This route produces both furoic acid and furfuryl alcohol. It can also be obtained biologically using microorganism Nocardia Corallina [81]. The yield of biological process is 88% from furfural and 98% from furfuryl alcohol. There is a challenge to develop a chemo-catalytic route for production of furoic acid from furfural or from constituents of biomass in an economical and efficient manner.

77

4.2 Value-added chemicals from lignocellulosic biomass

TABLE 4.3 Literature reports on oxidation of 5-HMF to FDCA. S. no. Catalyst

Base

Oxidant

Temp. (°C)

Time (h)

FDCA yield (%)

References

1.

Pt/ZrO2

Base free

4 bar O2

100

12

97.3

[69]

2.

Pt/Al2O3

1 equiv. Na2CO3

1 bar O2

75

12

96

[70]

3.

Fe3O4@C/Pt 1.67 equiv. Na2CO3

1 bar O2

90

4

84

[71]

4.

Pd–Au/HT

2 equiv. NaOH

O2 @ 60 mL min

60

6

90

[72]

1

5.

Pd/HT

Base free

1 bar O2

100

7

99

[73]

6.

Au/HY

0.3 bar O2

60

6

99

[74]

7.

Au/TiO2

5 equiv. NaOH

8.

Au/m-CeO2

4 equiv. NaOH

10 bar O2

70

4

92

[75]

9.

Ru/C

1 equiv. CaCO3 1 equiv. Na2CO3

2 bar O2

120

5

95 93

[76]

10.

Ru/ MnCo2O4

Base free

24 bar air

120

10

99.1

[77]

11.

MnCo2O

20 bar O2

8.34 m KHCO3

100

24

70.9

[78]

85

4.2.18 2,5-Dimethylfuran Recently 2,5-dimethylfuran (DMF) has gained lot of attention as it can be used as biofuel. DMF is a very stable molecule and is insoluble in water and hence it does not absorb water from the atmosphere. It has 40% greater energy density than ethanol and hence has comparable properties to gasoline. Its boiling point is around 92 °C and requires less energy during its production process. The research octane number of DMF is 119. It can be obtained from biomass derived sugars such as glucose or fructose [82]. Glucose or fructose is first converted to 5-hydroxymethylfurfural which is then hydrogenated to DMF (Fig. 4.18).

FIG. 4.18

Synthesis of 2,5-dimethylfuran by bio-based route and its applications.

78

4. Conversion of agricultural crop waste into valuable chemicals

DMF is an important intermediate for the synthesis of p-xylene and it’s global market is around 40 metric tons per annum. DMF can also be converted to γ-valero lactone which is an important chemical and also used as a green solvent.

4.2.19 1,3-Butadiene 1,3-Butadiene is an important chemical required to manufacture tires in rubber industry. Its other applications are in electronics, automobiles and for house piping. It is currently obtained from petroleum feedstock naphtha or gas-oil as a by-product during ethylene manufacturing process. It can be produced by dehydrogenation of butane too [83]. 1,3-butadiene can also be derived from renewable resources. The sugars obtained from lignocelluloses are converted to alcohols (ethanol, butanol) [84], butenes, and butane-diols which can in turn be converted to 1,3-butadiene (Fig. 4.19) [85]. It can also be obtained in one step from sugars by fermentation route. Syngas can also be converted to 1,3-butadiene, syngas is first converted to 2,3-butanediol which on catalytic conversion will give 1,3-butadiene [86].

4.2.20 1,4-Butanediol 1,4-Butanediol is an important chemical that can be used as solvents, in polymers and in speciality chemicals. The global annual market for 1,4butanediol is around 2 million metric tons. It is generally prepared from petrochemical feedstocks. Acetylene and formaldehyde are reacted to form 1,4-buanediol via 1,4-butynediol. Other process practiced is oxidation of propylene to 1,4-butanediol. Yet another process used is esterification of maleic anhydride followed by hydrogenation to form diethylsuccinate which is further converted to 1,4-butanediol. It can also be manufactured from renewable resources, i.e., sugars by fermentation route. Commodity sugars are treated with Escherichia coli for biological conversion to 1,4-butanediol [87]. Another route available for synthesis of 1,4-butanediol via catalytic upgradation of succinic acid which is obtained by fermentation of sugars [88]. There is a challenge to develop an efficient, sustainable process for catalytic conversion of succinic acid to 1,4-butanediol (Fig. 4.20).

FIG. 4.19

Synthesis of 1,3-butadiene by bio-based route and its applications.

4.2 Value-added chemicals from lignocellulosic biomass

FIG. 4.20

79

Synthesis of 1,4-butanediol by bio-based route and its applications.

4.2.21 Ethyl lactate Ethyl lactate is an important chemical which is manufactured by esterification of lactic acid and ethanol. It is prepared from renewable chemicals like ethanol and lactic acid [89]. It is used as a biodegradable solvent. It is used as replacement for solvents that are derived from petroleum resources for number of applications. It is used in metal cleaning, degassing machine parts, dispersant, used for coating and resin, flavor in food industry, etc.

4.2.22 Glycerin Glycerin is a very important chemical as it has very wide utility in polymer industry, pharma industry, food industry, and cosmetic industry; it is also used in resins, detergents, explosives, etc. (Fig. 4.21). It can be produced from propylene a petroleum feedstock using epichlorohydrin process. In this process, propene is first converted to allyl chloride which is then oxidized to dichlorohydrin which in turn on ring closure is converted to epichlorohydrin. Epichlorohydrin further treated with base to form glycerin. Biodiesel is produced by transesterification from renewable resources such as animal fat or vegetable oil and glycerin is formed as major by-product [90]. Glycerin has many other applications in production of various chemicals [91]. Glycerin can be biologically fermented to produce 1,3-propanediol. Citric acid is also produced by

FIG. 4.21

Synthesis of glycerin by bio-based route and its applications.

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fermentation of glycerin using Yarrowia lipolytica, crude glycerin can be utilized to produce hydrogen gas by fermentation or through gasification. Glycerin can be converted to fuel additives used in diesel and gasoline engines. Glycerin can be converted to an important chemical propylene glycol by hydrogenolysis. Succinic acid too can be produced from glycerin using bacteria named Basfia succiniciproducens. It is also used as an animal feed as an alternative to corn.

4.2.23 Isoprene Isoprene is a very important building block as it is used for manufacture of butyl rubber, polyisoprene rubber and styrene copolymer which are used for manufacturing tires. Presently, isoprene is produced from petroleum feedstock. Naphtha or gas oil is used as a feedstock for producing C-4 and C-5 carbon molecules including isoprene by cracking process. Isoprene can also be produced from biomass derived glucose by anaerobic bioconversion using engineered E. coli [92]. Study is still going on to produce bio-isoprene from lignocelluloses in an economical and efficient manner.

4.2.24 p-Xylene p-Xylene is an important chemical and is used to produce terephthalic acid and dimethyl terephthalate. Terephthalic acid and dimethyl terephthalate are starting materials for the manufacturing of polyethylene terephthalate bottles. The requirement of p-xylene worldwide is more than 40 million tons. It is produced by catalytic reforming of naphtha derived from fossil fuels as a part of BTX. p-Xylene can be distilled from mixture of aromatics BTX (benzene, toluene, and xylene) which is then separated from other constituents such as m-xylene, o-xylene, ethyl benzene, etc. This separation process adds to the cost and hence there is a need of alternative process. It can also be obtained from renewable biomass components such as sugar or lignin (Fig. 4.22). Sugar can be converted to isobutanol by fermentation reaction. Isobutanol is then dehydrated to gives isobutylene which is further dimerized to produce di-isobutylene

FIG. 4.22

Synthesis of p-xylene by bio-based route and its applications.

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which on dehydrocyclization gives formation of p-xylene [93]. It can also be produced from 2,5-dimethylfuran by Diels Alder reaction with ethylene [94]. Glucose can be first converted to HMF, which can further converted to 2,5-dimethylfuran which can in-turn undergo Diels Alder reaction with ethylene to form oxanorbornene cycloadduct which on further dehydration reaction forms p-xylene. Lignin from biomass can be converted to BTX (benzene, toluene, xylene) in the presence of H2 from which p-xylene is separated [95]. p-Xylene is also produced from limoline which is found in citrus fruits.

4.3 Conclusions and future prospect Utilization of agricultural crop waste/lignocellulosic biomass for production of fuels and industrially important chemicals will reduce the dependency on fossil fuels and reduce the environmental pollution. Lignocellulosic material is pretreated to separate its main constituent such as cellulose, hemicellulose, and lignin. In this chapter, we have described some of the industrially important chemicals/fuel additives, its preparation by bio-based route as well as petrochemical route and highlighted its application in various sectors. In overall, more efforts are needed to develop sustainable, cost effective, environmentally benign routes for the production of bio-derived chemicals. The novel intensified process/reactors, multifunctional catalysts or phase transfer catalyst, reaction media, are highly desirable as they allow the reactions to be feasible in single or two step, which will ultimately reduce the intermediate separation/purification operations. In addition, regeneration and recycle of the catalysts, the efficient downstream processing of target products, and scale up of process at commercial level are necessary for development of sustainable bio-based processes in future.

Acknowledgments Financial support from, CSIR Bulk mission mode project HCP-028C, Government of India for this work is gratefully acknowledged. Chetana R. Patil profoundly acknowledge Council of Scientific & Industrial Research (CSIR), for the award of Research Associateship vide reference no. 31/011(1141)/2020-EMR-I for the financial assistance to carry out this work.

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[78] S. Zhang, X. Sun, Z. Zheng, L. Zhang, Nanoscale center-hollowed hexagon MnCo2O4 spinel catalyzed aerobic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid, Catal. Commun. 113 (2018) 19–22. [79] P.V. Rathod, S.D. Nale, V.H. Jadhav, Metal free acid base catalyst in the selective synthesis of 2,5-diformylfuran from hydroxymethylfurfural, fructose, and glucose, ACS Sustain. Chem. Eng. 5 (2017) 701–707. [80] W. Jia, J. Du, H. Liu, Y. Feng, Y. Sun, X. Tang, X. Zeng, L. Lin, An efficient approach to produce 2,5-diformylfuran from 5-hydroxymethylfurfural using air as oxidant, J. Chem. Technol. Biotechnol. 94 (2019) 3832–3838. [81] Z. Zheng, Q. Xu, H. Tan, F. Zhou, J. Ouyang, Selective biosynthesis of furoic acid from furfural by Pseudomonas putida and identification of molybdate transporter involvement in furfural oxidation, Front. Chem. 8 (2020) 587456–587466. [82] X. Kong, Y. Zhu, H. Zheng, F. Dong, Y. Zhu, Y.W. Lia, Switchable synthesis of 2,5dimethylfuran and 2,5-dihydroxymethyltetrahydrofuran from 5-hydroxymethylfurfural over Raney Ni catalyst, RSC Adv. 4 (2014) 60467–60472. [83] J. Rischarda, C. Antinorib, L. Maierb, O. Deutschmann, Oxidative dehydrogenation of n-butane to butadiene with Mo-V-MgO catalysts in a two-zone fluidized bed reactor, Appl. Catal. A. Gen. 511 (2016) 23–30. [84] G. Pomalaza, P.A. Ponton, M. Caprona, F. Dumeignil, Ethanol-to-butadiene: the reaction and its catalysts, Catal. Sci. Technol. 10 (2020) 4860–4911. [85] F. Jing, B. Katryniok, M. Araque, R. Wojcieszak, M. Capron, S. Paul, M. Daturi, J.M. Clacens, F. De Campo, A. Liebens, F. Dumeignilae, M. Pera-Titus, Direct dehydration of 1,3-butanediol into butadiene over aluminosilicate catalysts, Catal. Sci. Technol. 6 (2016) 5830–5840. [86] T. Hanaoka, S. Fujimoto, M. Yoshida, Efficiency estimation and improvement of the 1,3Butadiene production process from lignin via syngas through process simulation, Energy Fuel 31 (2017) 12965–12976. [87] A. Burgard, M.J. Burk, R. Osterhout, S.V. Dien, H. Yim, Development of a commercial scale process for production of 1,4-butanediol from sugar, Curr. Opin. Biotechnol. 42 (2016) 118–125. [88] S.D. Le, S. Nishimura, Highly selective synthesis of 1,4-butanediol via hydrogenation of succinic acid with supported Cu-Pd alloy nanoparticles, ACS Sustain. Chem. Eng. 7 (2019) 18483–18492. [89] S. Figalla, J. Petruj, T. Svestkova, Transesterification of lactic acid oligomers with ethanol, a way to anhydrous ethyl lactate: a kinetic study, Molecules 23 (2018) 2044–2057. [90] M.R. Monteiroa, C.L. Kugelmeier, R.S. Pinheiroc, M.O. Batalhad, A.S. Cesar, Glycerol from biodiesel production: technological paths for sustainability, Renew. Sustain. Energy Rev. 88 (2018) 109–122. [91] H.W. Tan, A.R.A. Aziz, M.K. Aroua, Glycerol production and its applications as a raw material: a review, Renew. Sustain. Energy Rev. 27 (2013) 118–127. [92] A.O. Chatzivasileiou, V. Ward, S.M. Edgar, G. Stephanopoulos, Two-step pathway for isoprenoid synthesis, PNAS 116 (2019) 506–511. [93] A.G. Dedov, A.S. Loktev, A.A. Karavaev, I.I. Moiseev, A novel direct catalytic production of p-xylene from isobutanol, Mendeleev Commun. 28 (2018) 352–353. [94] X. Feng, C. Shen, K. Ji, J. Yina, T. Tanm, Production of p-xylene from bio-based 2, 5-dimethylfuran over high performance catalyst WO3/SBA-15, Catal. Sci. Technol. 7 (2017) 5540–5549. [95] A. Heeres, N. Schenk, I. Muizebelt, R. Blees, B. De Waele, A.J. Zeeuw, N. Meyer, R. Carr, E. Wilbers, H.J. Heeres, Synthesis of bio-aromatics from black liquors using catalytic pyrolysis, ACS Sustain. Chem. Eng. 6 (2018) 3472–3480.

C H A P T E R

5 Membrane-based treatment of wastewater generated in pharmaceutical and textile industries for a sustainable environment Monti Gogoia,b, Rajiv Goswamib,c, and Swapnali Hazarikaa,b a

Chemical Engineering Group, Engineering Sciences and Technology Division, CSIR-North East Institute of Science and Technology, Jorhat, Assam, India, bAcademy of Scientific and Innovative Research (AcSIR), Ghaziabad, India, cCSIR-North East Institute of Science and Technology, Jorhat, Assam, India

5.1 A brief overview on pharmaceutical and textile waste The waste generated from different pharmaceutical and textile industries possess an unprecedented risk to environmental sustainability. Due to this, the civilized countries demand for a revolutionary outbreak toward minimization of waste. The development of regulatory path for waste minimization is carried out for consecutive health concerns as well as environmental care. The reported database of the pollution control board evaluated that one-third of wastewater come from industrial effluent discharge, which contributes to the potential hazards and eventually disturbs the ecological balance [1]. One of the most important critical raw waste of the pharmaceutical industry is water. Wastewater generated from industry effluent is categorized as potable water, water coming from by-products. The water used in industrial sectors is mainly as the ingredients, raw material, processing

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and formulation of pharmaceutical products, active pharmaceutical ingredients and analytical reagents. Therefore, a complex composition of pharmaceutical-based wastewater includes organic matter, microbial toxic ingredients as well as a higher amount of salt form [2]. The differentiation strategy of the production process and productivity scale in pharmaceutical industries is reflected as a major effective source of waste generation. The expeditious growth of industrialization has increased the inter-relation between pollution and the environment. Industries mainly focus on the surface water bodies for wastewater disposal. The quantum jump of pharmaceutical industries have evaluated the chemical aggregation of wastewater as the organic matter of biodegradable behavior which includes the varieties of antibiotics, excess content of analgesics, antihistamines, reproductive hormonal, and lipid regulations. The presence of transition metal contaminants like cadmium, mercury, nickel, chromium, lead can be attributed to their devastating properties on waste disposal processing [3]. Genotoxic and mutagenic effects of wastewater have predicted a considerable impact on flora and fauna varieties depending upon the quantitative disposing of waste resources. The waste receiving the power of water bodies can also be evaluated with the help of highly generate textile industry, where the physicochemical and biological behavior of effluent discharged water content provides a requisite of a global initiative to the living organisms. The coloring and processing power of textile-based industries can act as an effective driving force for the maintaining of waste generation [4]. The dyeing, treating, and rinsing of textile-discharged gallons of waste into water reservoirs contain harmful and toxic chemicals like formaldehyde, metal contaminations like lead, mercury. Therefore, basic components found in textile waste include organic and inorganic hybrids of aromatic amines, salts, toxic metals and also carcinogenic chlorine and pigment systems [5]. The toxic metals present in the textile industry effluent include two types of contaminants, viz., the impurities impregnated with chemicals used for the processing routes of textile (sodium carbonate, salt and caustic soda) and the raw stuff of mordant metallic dyes present in complex format [6]. Sulfur-containing metal complexes are also present as converted sulfur to sulfide during the removal of oxygen through the biologically demanding of oxygen in the effluent. The oil and grease materials liberated from the textile industry form a broad spectrum of coating film over the water surface and therefore possess a very sensitive negative impact on the ecological view of surroundings [7]. The chlorine derivatives present in the waste stream are obtained in the form of residual chlorine. Wastewater disposed of without any prior treatment depletes the level of dissolved oxygen barrier and increases reaction efficiency with the other compounds. The residual chlorine has thereby brought out their toxic effect on the water bodies. The effective gauss of wastewater can be controlled by the

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quantification of BOD and COD value, where BOD measures dissolved oxygen level required to disintegrate the organic materials through an anaerobic process and COD can be determined by the equivalent value of chemically oxidized organic materials and their estimation is carried out by the addition of dichromate solution to the wastewater stream [8]. Textile waste is one of the effective bridges to initiate harmful diseases in human bodies. The dye effluent drainage from the textile industry is mainly dominated by the dyestuff, having bad color and odor. The disease including hemorrhage, nausea, ulceration, and severe irritation of skin are mainly out breaking of textile waste, leading to harmful potentiality to disrupt the ecological balance. The penetrating power of sunlight from an outer layer of the water surface is enhanced by their waste composition and hence prevents the mechanism of photosynthesis. The growth rates of photoautotrophic organisms are also reduced by the lowering level of biochemical oxygen demand and hamper the flora variety. An increase in the concentration of total dissolved solids and suspended solids on a waste stream can interfere with the oxygen transfer processes and hence play an important role in damaging the controlled effect of pollution [9]. Dye molecules are considered as colored substances, which can chemically bond to the substances to which it is applied. The different organic fragments mainly chromophores and auxochromes are responsible for the color imparted to the dye molecule. Mostly wide variety of dye sources includes the textile industry, paper industry and printing factories. Among the different industries available for dye molecules, the important one is the textile industry. Structural varieties of dye molecules include azo, diazo, metal complex, acidic, basic, and dispersed and anthraquinone [10]. Dyes are generally discharged from the scale-up process of textile industries and their colorants can be divided into synthetic and natural classes. Synthetic dyes are classified depending upon their adjacent organic groups and their mode of application. The metal contaminants found in the chromophoric skeleton of dye molecules include cobalt, copper, chromium, zinc, iron, mercury, lead, which have significantly disturbed the atmospheric equilibrium eluted from the industrial effluents [11]. In general, the industrial processes are accompanied by the use of different raw materials which can undergo chemical transformations giving rise to the formation of products and fraction of waste materials. Hazardous waste mainly liquid fractions produced by industrial applications due to reactive metal and their derivatives become a serious threat to the environment and human beings also. Among the different industries, the textile industry has gained a matter of considerable attention to the dye effluent. The quantitative estimation of color, pH, total dissolved solids, metals, BOD, and COD is considerably high in effluent composition. The discharged materials from these

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industries include colored organic substances with a high metallic load which can enormously affect environmental pollution. The high lighten mutagenicity of the components can adversely change human health as well as other organisms due to the ingestion of dye contaminants water. As a consequence, different process evaluations become very much necessary to combat anthropogenic contaminations. There are numerous techniques, used for the removal of these type of hazardous organic doses including incretion, can form dioxin and furan on incomplete combustions. The adsorptive phase transfer of contaminants is limited to some extent due to their considerable danger on separation [12]. These processes are not entirely appropriate for the removal of contaminations from industrial waste. Therefore, there is an urgent need to adopt new modifications to current regulations for controlling the organic load effluent (Fig. 5.1). The rapid growth of cells, regulatory function of body temperature, and nutrient absorptions are generally controlled over by water absorption. The assimilation of vitamins, amino acids, glucose, minerals, and other active substances into animal bodies is subjected to water intake. Therefore, there is a need for pure water for the animal as well as plant life. Increasing demand of modern civilization, industrial and agricultural processes, technological applications have contaminated the water bodies by the discharge of industrial and domestic effluents, marine dumping, radioactive deposition [13]. The organic, inorganic, and macroscopic contaminations of water bodies need to be protected to avoid the tremendously negative effect on environmental sources. The adverse effect of dyeing industries on water contamination has now become a matter of great concern since dye effluent contains carcinogenic, mutagenic, or toxic substances. The anthropogenic activities of dye molecules provide

FIG. 5.1 Composition of waste from textile and pharmaceutical industries.

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disintegration of the food chain providing biomagnification, imbalance the rate of biological oxygen demand (BOD) and chemical oxygen demand (COD), provide recalcitrance and hence cause aesthetic damage to water bodies. These organic molecules are needed to be removed and replenish the water sources for environmental remediation. The wastewater treatment approaches toward the use of different biological and chemical aerobic and anaerobic processes. Enhancement of different processes like activated sludge, reverse osmosis, gravity, adsorption, ion exchange, and others are carried out by the considerable imposition of membrane separation [14]. The introduction of membrane science in industrial and biochemical applications have attracted immense challenge toward the resolving power of water contaminations. During the last couple of decades, membrane science has grown significantly to fabricate a potential platform between the economical and sustainability gap, easy accessibility to chemical requirements and capital cost, energy, and quality performance of membrane permeation [15]. There is a need for more efficient membrane processes with some modifications including the use of ultrafiltration, nanofiltration, reverse osmosis, and forward osmosis. The use of membrane barrier for removal of hazardous colorful organic dyes includes different driving force mediated membranes like equilibrium, non-equilibrium, pressure-driven, and non-pressure-driven processes [16]. There is a continuous modification of membrane surfaces for better separation of heavy metal oxide and its derivatives from water resources. Therefore, they have gained a needful support from the addition of nanomaterials like TiO2, ZnO, Al2O3, and graphene-based carbon allotropes, and sometimes their physical and chemical performance is carried out by functionalization with the reactive functional group throughout the organic–inorganic modification [17].

5.2 Wastewater: A source of environmental hazards Wastewater generation in pharmaceutical industries is mainly due to the fermentation process, which contains a large number of organic substances and very much suitable for anaerobic digestion. The disruption of aquatic ecosystems is mainly led by pharmaceutical waste, which can diffuse organic loadings into the available local water bodies. Depending upon the type of fabrics including cellulosic materials, synthetic fabric and protein fabrics, the rate of generation of waste is varied. The fiber production procedures in textile sectors involve both dry and wet processes, where the wet process use potable water bodies and releases a considerable amount of waste into them [18]. The dyes and chemicals used in these textile industries have broken down the environmental feasibility to the soil and water surface.

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Numerous water pollutants include oxygen-demanding wastes, plant nutrients, pathogenic micro-organisms, synthetic organic and inorganic materials, radioactive substances, different radiation sources. Different types of sewage like domestic, industrial and storm sewage are included as a primary source of waste contaminants. Nearly 99.9% of domestic sewage contains water molecules despite having dissolved suspended solids. Another important characteristic of wastewater is suspended solids which contain soils, biological solids, decaying organic matters discharged in water effluent. Domestic water sewage has a greater percentage yield of nitrogen and phosphorus causing the natural growth of algae and accelerates the natural aging of physiological substances mainly eutrophication. Another major threat to the water body is contributed by the hydrocarbon derivatives emitted from the pharmaceutical industries along with different chemical factories [19]. Anthropogenic heavy metals were found to be another source of contaminations and they are generally released from industrial and sewage disposal. Most of the heavy metals like zinc, copper, arsenic, iron, and nickel are highly toxic and carcinogenic toward a physiological state of aquatic flora and fauna. The majority of waterborne micro-organisms include a pathogenic virus, aerobic and anaerobic bacteria, protozoa, etc. [20]. These are the most common potential hazardous water pollutant for the entire animal and plant kingdom undergoing a wide range of infections. The majority of organic wastes and endocrine disruptor include detergents, food, cosmetics, paper products disposal from commercial, industrial, and agricultural sources.

5.3 Effective performance of membrane on wastewater Numerous processes like ultraviolet radiation, ozonation, advanced oxidation process have been used to ensure the subtraction of water contaminations. Among those, the biological treatment processes are involved with aerobic digestion of effluent and anaerobic waste minimization, while the chemical treatment is associated with the destruction of organic matter undergoing photocatalytic oxidation, chemical oxidations, etc. [21]. A recent number of studies have revealed that the conventional wastewater treatment processes are unable to eliminate an adequate level of a pollutant from their available biological resources. Therefore, there have been needs for the complete exclusion of treated effluents through some appropriate modifications. A large number of reported literatures have pointed out a milestone on the membrane-based chiral resolution processes with the most promising technology. Cram et al. first reported the vital role of membrane surface on the enantioseparation of a racemic amino-acids mixture with catalytic

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influence [22]. They have devoted to the substantial membrane approach toward regulatory biological responses due to its prevailing contribution to numerous physiological processes. Afonso et al. gave a research momentum on the scale-up enantiomeric separation with the advent of technological integration of stereoisomerism [23]. After all, they have proven membrane as an integral surface barrier for the identification of organic molecular fragments. Although the use of chiral liquid membranes has been investigated as a single unit enantiomeric separation process, the recent literature reviewed their limitation to the extent of solution vaporization, relatively low stability and non-efficient separation of targeted species and lack of structural stereospecificity [24]. Researchers have demonstrated the use of polypeptide multilayer as a membrane surface for the analytical enantioseparation of ascorbic acid and L-DOPA and this type of membrane exhibited a higher flux value as compared to other reported chiral membranes [25]. The different process variations on the use of membrane separation were also discussed through some reported literature. Xie et al. summarized a comparative overview on the membrane-assisted adsorption-enantioselective separation of chiral organic complexes [26]. The presence of different reactive functional groups on the organic residue has also determined their rate of separation through particular phase mediated membrane processes. The two such types of phases generally include solid and liquid form. The fabrication of the liquid membrane process involved types of processes and categorized as a bulk liquid, emulsion liquid and supported liquid membrane. The removal of textile waste has demanded a technological approach toward treatment purposes. Therefore, physicochemical parameters like concentration, composition and characteristics are considered for membrane-based waste treatment. In this framework, several efforts have been applied to introduce the conventional process of wastewater treatment including filtration, flocculation followed by coagulation and several biological approaches [27]. In the last decades, the current discharge of waste into the environment is now controlled by one of the major boosts of membrane technology. A membrane is a selective barrier between two phases, having a power of restriction to the movement of components through it in a selective manner. The two general classifications of membrane, isotropic, and anisotropic exhibit different physical characteristics and chemical performance. The anisotropic membranes are considered as a comparatively better one on the reverse osmosis process of water desalination due to the presence of a thin supportive layer followed by the highly permeable layer [28]. The dense microporous membranes are limited to their lower permeation fluxes. The isolation of particular enantiomers through the membrane separation process is greatly enhanced by the characteristic properties of low

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energy usage, better efficiency, simple and continuous operability. Abundant value addition of enantiomeric recognition site over membrane surface brought about their selective permeation and rejection involving the type of chemical interactions like absorption, diffusion, adsorption, etc. [29]. The diffusion selective permeability of membrane surface provides differentiation on the optical isolation of chiral compounds. The different binding affinities like Coulombic force, van der Waals interaction, hydrophilic and hydrophobic intercalation influence the substantial performance of membrane surface. The stereospecific interaction of a particular isomer with the recognition site of the membrane barrier is one of the preliminary importances of chiral selectors. The addition of different carbon allotropes on the doped polymeric solution can give selectively better permeation of one of the chiral isomers [30]. The disintegration of structural similarities and some of the physical characteristics of isomeric compounds are dominated by their chemical improvements. The facilitated and retarded transport of compounds on solid-phase membrane surface represents the mechanistic outbreak of membrane separation. Mostly, the principle of facilitated transport membrane process is based on the preferential absorbance of one of the isomeric compounds to the recognized site with a strong intermolecular binding affinity and finally transported through the influence of concentration driven permeation or electro-potential gradient, while another stereoisomeric component having relatively lower binding tendency get diffused through the membrane barrier [31]. The successful interaction of analyte solution and reactive functional sites of chiral isomer gives a better yield of permeate when separating through the recognized hole of the membrane surface. Therefore, the enantioselective membrane function promotes retarded separation with the assimilating driving forces of pH gradient, pressure, temperature, concentration variation and electrical potential. The magnitude of these forces can affect the efficient separation of a particular enantiomer. The requirement of lower energy with reduced size of equipment is one of the better perspectives of the membrane selective treatment process. The potential effectivity of membrane-based process is on the trend of low or decrease in chemical usages, an economical gap with sustainable feasibility and eco-friendly accessibility [32]. Therefore, current scenario of waste generation is broadly controlled by the membrane-based processing way. Exploring the membrane modification through hybrid overlapping of adsorption and coagulation can also develop the membrane feasibility on account of the waste disposal from industry effluent. The characteristics overview of a membrane can be justified with two types of physical interpretation, which includes isotropic and anisotropic. The uniform composition of a membrane with a definite physical structure possesses a micro-porous surface and falls under the category of isotropic

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morphology thereby exhibiting the increase in the rate of permeation through a surface barrier. The anisotropic character of the membrane surface is reflected throughout the reversed criteria and hence exhibits the supportive layer of any coating or doping over the surface outer-phase. Pressure-driven membrane processes are applied to the wastewater treatment process. The variation of pressure and pore size of membrane surface are very much effective toward the types of membranes which include microfiltration, ultrafiltration, nanofiltration, and reverse osmosis [33]. More broadly, the use of a reverse osmosis membrane is most advantageous because the strong hydrostatic pressure generated is strong enough for the osmotic pressure created intrinsically on the feed part. During the treatment procedures, the molecules are undergoing adsorption on the membrane surface followed by diffusion of membrane cell and then desorbed toward feed counter. Reverse osmosis membranes are widely used for the recovery of monovalent ions like chloride and sodium whereas, the larger pore size of ultrafiltration and nanofiltration membrane allows the passage of multivalent ions agglomerated with types of poly-electrolytes and micelles. The pressure is applied on the concentrated side of the membrane and allows the permeation of waste generated from pharmaceutical and textile industries into the dilute side. The ultrafiltration behavior of the membrane can be evaluated with the facilitated transport of organisms that are not sufficient enough to pass through the respective pore size of the membrane. On inducing the RO membrane, the contaminant ions and fraction of dissolved ions can be removed from waste disposal and a higher degree of fluctuating tendency in water demand is one of the basic criteria considered under reverse osmosis treatment [34]. The combining effect of electricity and ion permeability plays a potential effect on the membrane-based separation of dissolved ions from pharmaceutical waste. The electrical potential gradient applied during membrane permeation transport the ions from dilute solution to concentrated solution using an ion-exchange type of semi-permeable barrier. The electrostatic charge effect is the driving force for the treatment of generated waste on the resin membrane. Ion exchange resin can replace the charged ions mainly nitrate ions and hardness of water from waste contaminations [35]. Per-vaporation is another phenomenon of membrane treatment applied for the wastewater treatment coupled with permeation followed by evaporation of liquid. The more permeable fraction of feed solution gets easily sorbed through a polymeric microporous and nonporous membrane and gradually undergoes diffusion due to the concentration gradient across the diffused species. The subsequent evaporation of the waste occurs at the downstream phase of the membrane. The well-known solution-diffusion model plays an important role in the vapor

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condensation, and therefore, liquids are recovered. The hybrid membrane process can be used as an improved separation technique for wastewater treatment which undergoes a series of chemical phenomena including adsorption, coagulation and desorption and therefore reduces the rate of membrane fouling [36]. One of the most common uses of hybrid membrane used in the process efficiency of membrane treatment is the activated carbon incorporated low pressure driven ultrafiltration and nanofiltration membrane. Membrane bioreactors have the purpose of recovery of resources from wastewater involving activated sludge treatment of membrane process. Membrane bioreactors are mainly used in two different types of configurations includes membrane-based side stream and immersed bioreactor. The state of physical and chemical properties such as temperature, pressure, crossflow rate, velocity can significantly affect the rate of elimination of inorganic ions like Ca2+, Mg2+ Na+, SO2
4 . These ions can strongly bind with the carboxyl group of polyamide layer of RO and NF membrane and result in charge reversal neutralizations [37]. The solute-solute interactions of macro-organic complexes and water pollutants have triggered a substantial effect on the membrane flux. During membrane filtration, one of the inevitable phenomena is membrane fouling. The setup operating conditions may affect the membrane fouling. The development of a thin layer on the membrane surface is also a necessary criterion. Because the turbulence generated during cross-flow filtration enters through deposited thin layers and thus decreases membrane fouling. Since non-porous RO membrane has dominating fouling characteristics on the membrane surface. The adsorption of organic matters, precipitation of inorganic metal oxides and the concentration of feed solutions can lead to the obstacle of membrane fouling with severe flux decline, increase in transmembrane pressure drop [38]. Hydrophilicity is an important parameter to deal with the membrane performance on water treatment. On separation of the variety of water contaminants, the hydrophilicity of membrane tends to resist attachment due to the adsorption of organic microbes and the surface is proven to be a low antifouling surface. The continuous accumulations of dissolved organic matters onto the membrane surface can block the available pores leading to a decrease in membrane permeability with the enhancement of solute transport. Membranebased water treatment mainly leads to organic fouling due to enrichment of metal oxides, dyes, inorganic ligand complexes, charged metallic species, microbes including bacteria, viruses present in feed concentration. The concentration of feed solution is also an important parameter to analyze membrane performance. To ensure the feasibility of the membrane process, the effect of feed concentration on permeates was generally studied under ambient conditions of pressure and temperature. The overall variation of TDS concentration of feed solution reduces solute undergoing concentration polarization and also decreases the flux value. This

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results in an increase in osmotic pressure and a decrease in transmembrane pressure [39]. The other parameters like feed pH, chemical structure, geometry, and hydrophilicity of solute can significantly affect membrane charge. Membrane performance on wastewater treatment is strongly affected by the following parameters namely:

5.3.1 Temperature The increase in temperature decreases the viscosity of water components and declines the rate of concentration polarization. When temperature increases, there is a scope of chemical integration on organic–inorganic hybrid and hence the value of COD gradually changes. Variable temperature can cause a change in diffusion coefficients and fluctuate the value of membrane flux [40]. The temperature change can significantly affect the electrical conductivity of oily-waste water due to the decrease in charge polarity.

5.3.2 Pressure Membrane permeates flux increases along with an increase in operating pressure due to the direct proportionality to each other. This linearity can be disturbed on some points because of the polarization of feed concentration and membrane fouling. The higher level of applied pressure can adopt easy transportation of solvents along with micro substances and hence the rejection of dye becomes most prominent at a considerable higher-pressure value [41].

5.3.3 Flow rate The increased flow rate value can possess greater removal of organic masses from wastewater. The rate of increase of permeate flux on a greater flow rate can decline the possibility of concentration of feed solution. The transportation of organic matters from feed solution increases at a higher value of flow rate concerning membrane hydrophilicity and pore distribution [42]. It is very much essential to describe membrane performance parameters like permeability and selectivity for better chiral resolution. The coefficient of membrane permeation is generally measured using a standard mathematical expression. Enhancement of membrane flux is carried out by a pressure-driven membrane process. A solution-diffusion mechanism determines the membrane permeation rate through uniform feed flow (P ¼ DS), where the linear correlation between the coefficient of permeability and diffusion factor determines the electrostatic interaction of

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membrane and chiral isomer. Membrane pore size can also significantly affect the permeation rate. Adjustment of temperature and pressure factor correlatively examine the rate of flow of permeate. Membrane-selective transport of chiral molecules was found to be determined by enantiomeric excess of permeate. Therefore, permeability factors were controlled under the concentration gradient of the feed mixture. The feed flow rate is also an emerging factor parameter to control the permeation ability. The solubility of one of the chiral isomers in feed solution is very much important for process applications. The selectivity of the membrane is one of the imposing parameters for chiral separation. Selective membrane performance has been controlled by the stimulating selectivity of an isomeric component. Mechanism of stereoselectivity was reported to be controlled by the separation factor, enantioselectivity, enantiomeric purity including determination of enantiomeric excess, purity, and recovery of the targeted enantiomer. Chemical characteristics of both enantiomeric mixture and membrane polymer must be relevant for each other to promote scale-up separation and fabrication of methodological steps. The retention time of two enantiomers on membrane selectivity has been established as an efficient route to recognize one of the isomers through inclusion or intercalation. The inducing effect of membrane performance is structurally improved by the transportation speed of the enantiomeric mixture [11,16]. Process inclusion of particular isomer on selected membrane pores is greatly enhanced by water permeability of membrane surface. In general, hydrophilic membranes have a better tendency to form inter or intramolecular hydrogen bonding with polymeric solution mixture. Polymeric membranes can have flocculant value toward membrane effective value addition of distinct chiral isomer separation. Diclofenac is one of the important pharmaceutical residues present in waste effluent. It is a drug having non-steroidal functionality, which can act as an anti-inflammatory drug to treat inflammation and pain associated with rheumatic diseases. The photocatalytic degradation of this drug can be attributed to their removal efficiency from the waste stream. The ozonation oxidation process coupled with the coagulation and flocculation is widely used to degrade the analeptic drug carbamazepine. Another important pharmaceutical waste is sulfamethoxazole (SMX). This drug is widely used in the treatment of gastrointestinal disease, diarrhea and it also bacteriostatic antibiotics. This drug can be separated from pharmaceutical waste undergoing a vacuum UV-mediated degradation process. The hybrid ozone membrane filtration process is an intrinsically important membrane filtration process for the treatment of pharmaceutical waste having an organizable tendency. These processes have evaluated the effect of ozone on river waste treatment accumulated from the different flow streams of industrial usage.

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5.4 Effect of nanocomposite membrane on wastewater treatment process The global challenge of waste disposal requires nanocomposite membrane filtration as a viable process technology applied to the demanding view of pure water scarcity [43]. The water quality of hardness, heavy metal removal and deduction of dissolved organic matter is mainly carried out by the use of nanofiltration membrane performance. The higher acceptance rate of a polymeric membrane having controlled pore size and adjusting the polymeric solution to be cast are valuable feed parameters to resource recovery from wastewater [44]. The unique chemical, structural and physical properties of membrane performance can be differentiated by incorporating the effect of nanoparticles into a suitable polymeric skeleton which leads to specific chemical adaptation like thin-film nanocomposite, thin-film composite with nanodimensional substrate and mixed matrix polymeric surface [45]. The advanced materials including modified Carbon nanotubes, polysaccharide matrixes, activated carbon, metal–organic framework, molecular imprinted polymeric compounds, thermoresponsive gels and magnetic nanoparticles have been identified as proper adsorbents during pharmaceutical waste treatment processes. The adsorptive performance of activated carbon on antibiotics removal from wastewater is carried out on examining the pharmaceutical waste like cephalexin, amoxicillin, tinidazole, trimethoprim (TRP), imidazole’s, nitroimidazoles, dimetridazole, metronidazole, sulfamethoxazole (SMX) ornidazole, penicillin, quinoxaline, sulphonamides, sulfamethazine, and tetracycline (TET) [46]. The powdered form of activated carbon has possessed a relatively better performance on generic as well as a granular form of materials. The implementation of allotropic carbon forms gives a recent spike of interest in the chiral selector. The effectiveness of optical resolution was found to be analyzed in terms of CNT. The unique surface plasmon resonance characteristics of CNT derivatives like MWCNT, FWCNT provide simple, sensitive chiral recognition for enantiomeric enrichment of membrane permeate [47]. The percentile composition of each enantiomer is further analyzed through chiral column chromatographic separation. They can also be used as pseudo stationary phases in the column compartment. Demanding utilization of CNT on a chiral resolution is due to their easy separation selectivity, better efficiency, and stability during the chiral chromatographic separation of stereoisomeric mixture [48]. Structural modification of outer CNT surface through inducing some kind of organic transformations have been reported as being an excellent pathway for achievement in biological, pharmaceutical and environmental applications.

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The theoretical point of view leads to the use of different chiral selectors accompanied with carbon nanomaterials for the perfect structural fitting of enantiomer to the three-point interaction. The poor solubility of CNT on an aggregation of van der Waals forces is greatly considered to be an advantageous challenge for a chiral selector. Therefore, their structural mitigation with types of chiral modifiers is very much essential. The helical wrapping of selective chiral compounds including long hydrophobic alkyl segment of surfactant, β-derivative of cyclodextrin membrane over CNT surface provides an effective route for enantioseparation process. Thereafter, the membrane performance has regulatory controlled by the force of interaction between CNT surface and racemic compound. The surface modification of CNT is generally fabricated on the outer compartment instead of the inner cavity, because there is a genuine steric inhibitory effect of a structural network within spiral graphene sheet of nanotubes. Due to the fragility and instability of the chiral stationary phase, the use of graphene sheets triggered a promising activity in the development of carbon-based chiral separator. The reported literature revealed β-CD modified GO-based membrane for the chiral recognition in cyclic voltammetry. The chiral molecule-functionalized holes in the stacked graphene layers act as an effective doorkeeper, which can promote the transport of chiral molecules across the flat sheets [49]. Emerging chiral resolution techniques have recently brought the use of graphene-based mesoporous materials in the field of carbonization enantioselective chemistry. However, the most specifically controlling interlayer distance between parallel graphite sheets plays a considerable role in the transport mechanism of a chiral guest. Many strategies were proposed to improve the enantioseparation of GO-based membranes. The L-glutamic acid incorporated GO flakes provide the required stability for their stacked sheets to overcome the force of dispensability within their fine spacing. They showed a superior magnitude in flux value of enantiomeric separation with an effective selectivity. The derivative monolithic carbon analogs such as reduced graphene oxides were also reported to be used for chiral separation. A doped polymeric solution of rGO can be used as a new variant alternative to the carbon-based stationary phase of chromatographic processes. 2D network of graphitic sheets can dramatically control the organic interactions of the chiral probes. Therefore, the bonding affinity of optically active substance to the cyclic hexagonal ring is carried under the influence of chemical stability of chiral recognition sites. Quantification of the separation process with variational retention time has proven to be another promising task of enantiomeric rejection. On functionalization of graphite sheet, different reactive organic fragments can be grafted to their outer layer surface, which in term exhibiting different permeation and rejection percentage

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of isomeric mixture. Thus, the pharmaceutical formulations can be estimated on robust chromatographic separation processes. Various physical adaptations of CNT are used in the removal of heavy metal contaminations, polycyclic aromatic hydrocarbon-based materials, metalloids, endocrine-disrupting metal species from waste generated from the manufacturing functionality of pharmaceuticals [50]. One of the important bioactive and environmentally feasible waste contaminations is phenolic compounds, where their photocatalytic decay is controlled by using TiO2 coated CNT membrane. Literature studies have evaluated the use of MWCNT on the adsorption of antibiotics like lincomycin and iopromide. Biocompatible and biodegradable effective source of Polysaccharide modified matrices including chitosan and cellulose beads are generally used as the base matrix of the adsorption process of dye effluent and heavy metallic impurities. An important dopamine-stimulating drug material generated from pharmaceutical waste is pramipexole dihydrochloride. For efficient recovery of it, the anionic grafting of sulfate and carboxylate group within chitosan matrix cross-linked with glutaraldehyde under controlled pH was used to facilitating the adsorption process. Chitosan complex matrices have gained considerable attraction for aquatic treatment of waste due to their highly reactive amino and hydroxyl functionalized group and therefore have significant adsorption toward the minimizing effect of dyes, phenolic compounds, and metal anions. The electrostatic interaction of chitosan with the metal contaminant like silver and arsenic is carried out under an acidic environment followed by an ion-exchange mechanism, and therefore, the continuous and batch performance of the chitosan-based membrane surface becomes good enough for the removal of metal derivatives. The chitosan adsorbents are widely used in various forms including clay and magnetic form, polyvinyl alcohol, and activated carbon. The basic physic-chemical parameters of chitosan derivatives are mainly concentrated on their low surface area, better hydrophilicity, and colloidal tendency to form a gel and highly efficient susceptible microbiological and biochemical degradation. Important anticonvulsant carbamazepine was separated from pharmaceutical waste using Ferric oxide functionalized chitosan polymeric membrane and therefore modified to prevail its therapeutic action [51]. Metal–organic frameworks are conventional adsorbents used for wastewater treatment and their special properties are characterized by their sponge-like crystalline nature. The adsorption behavior of this type of complex conjugate is due to their abruptly larger surface area, structural tenability, better thermal and mechanical strength. Most of the literature has made its contribution toward pharmaceutical waste recovery. The metallic parts adjusted with the reactive organic moiety have achieved

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Lead WASTE WATER

Copper

HEA VY M

ETA

Sodium

LION

S

Iron Manganese

DYE & O R COMPO GANIC UNDS

Nitrate Chloride

• Organic matter

• Microbial toxicity

BOD

COD PHARMA WASTE

TSS • High salt

TDS • Dissolved solids

FIG. 5.2 Representation of advanced nanomaterials used in the treatment of waste recovery.

better adsorbing power on the recovery of Naproxen and Clofibric acid from pharmaceutical waste. Their recovery efficiency is independent of the pH condition [52] (Fig. 5.2). In the textile industry, an integrated water treatment process has been accessed using sequential treatment of nanodimensional separation barrier. Most of the textile industries have treated waste as raw materials for the simultaneous recovery of energy as well as water. This methodology produces secondary waste fractions and the concentrated excess sludge followed by the chemical treatment with activated sludge. The settled down of insoluble mass is again filtered with a nanofiltration membrane to concentrate the desirable compound from the mixed matrix of waste. Mainly the highest percentage of waste in the textile industry is accompanied by organic loads, toxic compounds, colored derivatives, and salts. The dyeing process of the textile industry is a source of waste

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and is mainly aggregated by dispersing agents and surfactants. Therefore, various types of dyeing mechanisms use a low or high amount of salt concentration and hence evaluate the efficient route to develop waste storage. Two major distinct pollutants present in the dyeing materials are salt and heavy metal incorporated dye. Ultrafiltration membrane exhibits its better performance on the removal of binder and color in textile waste. The membranes are mostly working on the modified batch mode to reduce the BOD value and minimize the color [53]. Pharmaceutical effluents are the source of biowaste and mainly contain a large number of biological substances containing complex organic compounds and disinfectants which could provide toxic effects on the environment as well as human endocrine disruption. Advanced technology has been continuously providing several process technologies to treat industrial waste effluents. The different types of membrane bioreactors are fabricated which include the entrapped membrane reactor (BEMR) and salt marsh sediment membrane bioreactor (SMSMBR). These types of membrane reactors are highly efficient toward the pharmaceutical effluents containing large amounts of toxicity, salinity, and a higher level of COD. The production of biogas from waste effluent is an advantageous route to facilitate the reduction of waste frequency. For this purpose, literature has reported the use of an anaerobic membrane bioreactor or anaerobic bio-entrapped membrane reactor. The textile industry effluents have also contributed to the wool scouring effluent as a source of bio-waste. Therefore, the need for a membranebased coagulation-flocculation process is a way to generate the treatment of wool scouring effluent. A review of literature demands several biocomposites such as chitosan, polyurethane, and sucrose as a membrane material for the treatment of textile-based effluent. This biocomposite-based membrane process is carried out using the drop coating method. They possess higher performance in terms of COD and total suspended solid of effluent. Bio-film membrane-based bioreactors are another membrane-based technique to remove organic and microbial pollutants from the dairy effluent. The combination of membrane treatment with other biological and chemical methods has proven their higher rate of efficacy to accord the industry effluents. The advanced oxidation process coupled with membrane bioreactor is treated with the pharmaceutical residues to remove the contaminations from their liquid waste stream. The performance of the advanced oxidation process under the applications of the electric field environment is in the progress to remove the dye content from pharmaceutical effluents. Membrane distillation is a growing technology and it can effectively separate the water content under the application of heat energy depending on the solvent volatility. The vapor pressure gradient created across

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the hydrophobic microporous membrane allows the transportation of water vapor for separating the water from high feed content. Reported studies have evaluated the utilizing power of MD on the treatment of wastewater generated from textile sources [54]. The efficient membrane treatment controls the rate of distillate flux, permeate and temperature polarization during distillation. The larger pore size of membrane used on the distillation process exhibit very little resistivity power to the mass flow and hence enables the significant water content in the permeate side. The distillation process is operated under atmospheric pressure and the product quality is completely free from any contaminations. For commercial use of membrane-based separation technique, the packaging of the membrane occurs in different types including plat and flatform, tubular form, spiral wound, and hollow fiber form. The plat and flat form of membrane module is applied for the treatment of highly suspended solids present in wastewater. Tubular-shaped membrane modules are used to treat the feed of high solid content. Under controlled pressure, the outlet of permeate side is very much effective to catch upon the passage of solid waste content flowing through the tube shell. A spiral wound module is an aggregate of high packing density and having a relatively higher surface area. This is made up of permeate spacer and feed spacer section spiral over the central tube. The tangential flow of feed solution through the spiral wound is facilitated by permeate spacer and again collected at the end of the tube. The hollow fiber membrane module consists of a nonselective porous support layer having an active thickness. Therefore, pressure variation has brought out their performance through two ways likely outside feed and inside feed. The feed solution undergoes different stepwise flow within a spiral tube and therefore differentiated into permeate and retentate fractions. The present membrane-based separation of wastewater minerals has emphasized the recovery of valuable components at the cost of an increase in wastewater disposal. The hybrid NF and RO membrane processes have generated a high rate of mass transfer and permeate water economically instead of being vaporized or stream distillation with extensive heat supply. The performance evaluation of nonmaterial on wastewater treatment has withdrawn growing attention toward environmentally benign effluent discharge. To ensure potential technological applicability of domestic and other wastewater treatment processes, the effect of different factor parameters to lead to excellent effluent quality has gained utmost priority. Therefore, the use of improved strategically important membrane science has proven the challenging way to remove the contaminated water bodies on the demanding flow of civilization. The optimization of physicochemical properties of the membrane also demands the use of nanoparticles entity, which significantly increases the

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surface to volume ratio. The practical implementation of polymeric nanocomposite materials on the membrane technology now become established a challenging perspective to the specified contribution of membrane porosity, charge density and surface hydrophilicity. Although the demanding industrialization needs to dispose the effluent additives to the population-controlled developing countries, the use of science and technology aims to address their effective solutions.

5.5 Conclusion The pharmaceutical and textile industries are one of the larger consumable sources of water and therefore possess heavier damage to the ecological balance. The inefficacy of process treatment on the manufacturing of pharmaceutical and textile materials builds up lots of by-products accumulated with water body components. The evaluation of various modifications with single matrix components has demonstrated the treatment of industrial waste components involving types of chemical phenomena like adsorption, diffusion and solubility. These process modifications have controlled under physic-chemical parameters like temperature, pH, and adsorbent surface area. The single-step treatment process can eradicate the compositional aggregates of wastewater sources, and therefore, the recent research aims to develop the hybrid technology with extensive analysis of pollutants and their respective discharge limits. The utilization of biomedical processes on the potential growth of effluent treated strategies helps to use the water bodies in a sustainable manner maximizing the ecological balance. The demand for large-scale production of optically pure isomer has resolved the use of membrane-based chiral separation techniques. The inexpensive power, high selectivity, a greater mass transfer rate of the membrane have attracted considerable attraction on the significant enantioseparation of organic drugs. The biochemical properties of targeted isomer have reported their separation as a most promising approach toward industrial applications. For the better efficiency of membrane performance, it can be attributed to the excellent properties of CNM materials, more precisely carbon allotropes like graphene oxide, carbon nanotubes, fullerene, etc. The enduring research of chiral separation also introduces the types of chiral selectors acting as stationary phase and mobile phase depending upon their chemical inertness and structural lability. The good biocompatibility of chiral selector with the enantiomer to be separated maximizes the chiral recognition site over membrane surface and improves membrane efficiency. The fouling of porous membranes is diminished due to the achievement of chirality.

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C H A P T E R

6 Efficient and nutritive value addition of waste from food processing industries Alimpia Boraha,b, Rajiv Goswamib,c, and Swapnali Hazarikaa,b a

Chemical Engineering Group, Engineering Sciences and Technology Division, CSIR-North East Institute of Science and Technology, Jorhat, Assam, India, bAcademy of Scientific and Innovative Research (AcSIR), Ghaziabad, India, cCSIR-North East Institute of Science and Technology, Jorhat, Assam, India

6.1 A brief overview on food waste Food waste is one of the most important critical hazards to the environment. The industries that belong to the processing and treatment of food have also recognized the varieties of problems associated with their disposal level. Therefore, the civilizing countries are ever ready for utilizing the food waste generated from the food processing industries [1]. They possess a large number of residual contents coupled with a higher level of moisture, which can be very much effective for spreading health unconsciousness. During the production and consumption process, 20% to 40% of food waste is discarded. The evaluation of the processing chain can act as an efficient driving route towards minimizing the generation of waste through consumption of food waste in the form of other value-added products [2]. The classification of food waste is generally conventional which can cover up the two distinct major categories including organic and inorganic content. The organic polluted fractions are normally attributable to the consumption of human diet, restaurant, and luxurious lifestyle, whereas the inorganic contents of polluted residuals are due to the civilizing and innovative track way of process industries [3]. Organic food waste can be Advanced Materials from Recycled Waste https://doi.org/10.1016/B978-0-323-85604-1.00005-6

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converted into the form of energy and recovered in the form of heat and electricity. Evil consequences of food waste are due to the drop-down manner of unavoidable food contents which can be leaked out as by-products from different agro-based chemicals and will be highly valued after treatment and modification [4]. The supply chain of food waste is accompanied by the factor parameters including processing, production, preparation and finally consumption. The majority of food loss has occurred at retail and consumer price value. These entire factors play a highly effective role in favor of waste generated from food industries [5]. During the time of industrialization, the majority of food loss and waste occurred in the different localities. Food loss occurred along with the food chain of different sources. The various numbers of methods are responsible for the waste of food gradients in the different food chains. The main factor parameters that affect the irregular degradation of food chains are agricultural production, storage condition and transportation, processing techniques and consumer value. The agricultural production method is involved throughout the different poor harvesting techniques, failure to meet the quality standard, climate condition and improper storage system [6]. The overloading of stocks in market places, poor forecasting and damage in suppliers are also the factor of food waste under distribution and retail suppliers. The challenging era of biological and environmental research has been mostly dominated over the phenolic waste from different process industries, which mainly includes derivatives of polyhydroxyphenols. The chemical structure of polyphenols is the cross-linked version of an alkyl chain, linking more aromatic moieties bearing polar hydroxyl groups in quantitative numbers [7]. Over the last 10 years, around 10,000 polyphenolic compounds have become identified in various natural plant sources. They are secondary metabolites and abundant micronutrients in our diet. They have been withdrawing an effective vital role in metabolism, regulation of growth factor and act as a protective and inhibiting carrier for UV radiation and pathogenic micro-organisms (bacteria, virus, etc.). The most therapeutic action of polyphenols has brought about their potential effect on the prevention and treatment of oxidative stress-related diseases. Therefore, the isolation and concentration of polyphenolic compounds from waste compositions are very much necessary since they have attracted much more attention due to their reactive oxygen species. It can fight against neurodegenerative diseases and carcinogenic activities within the cell house of mammals. The bioavailability of polyphenols has been attributed due to their impressive superficially active nature including anticancer, antimicrobial, antiaging, cardiovascular disease, obesity, diabetes, asthmatic troubles,

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anti-inflammatory, antihypertensive, osteoprotective, cardioprotective, and kidney-protective. They are highly efficient towards modulating cell apoptosis, metastasis, angiogenesis, cell-proliferation, tumor cell growth, and metabolic syndrome. The structural evidence of polyphenols has revealed its structure as conjugated cyclic conformers, having organic residues like furans, pyrones, biaryls, aryl ethers, pyrans, dioxins, benzopyrans, O- or C-glycosides cross-linking through less polar alkyl moieties. The functionalization of reactive oxygen species is generally carried about by exposure to light radiation exhibiting a free radical mechanism and effectively gaining their photochemical stabilization through aromatic stabilization. Polyphenols can be broadly categorized into several classes depending upon the number of rings and heterocyclic residues present within the molecular fragment, these are-phenolic acids, lignans, flavonoids, and stilbenes. They are further differentiated into a variety of classes availing their organic residues parts adjusted with the phenolic ring. The stilbenes and lignans are mainly included under non-flavonoids parts. The stability of polyphenols has been mainly attributed to the conjugation of macromolecular fragments including polymerization reactions through several subsidiary steps like step-growth, enzyme-catalyzed radical mechanism, free radical grafting, etc. [8]. The antioxidant activity of polyphenols is mainly involved through the different steps of mechanistic pathways including hydrogen atom transfer scavenging free radical mechanism, chelating ability with transition metal ions, high energy electron transfer etc. This notable bioactivity has been widely studied due to their potential effects on reducing the oxidative stress in serum, decrease the level of oxidized low-density lipoprotein (LDL) and lipid peroxidation ability in plasma, protecting the membrane by reducing DNA damage and induction of dose–response signals on plasma. The antioxidant-rich polyphenols mainly spread over the natural bioactive abundant resources like green tea catechins, extracted grapes seed, almonds and walnuts, derivatives of hydroxytyrosols, pigmented rice components like anthocyanins, and some fruit additives. The antineoplastic drug action of polyphenols have been identified in the persistence of activation of nuclear protein complex factor-like NF- κ B to stimulate DNA- integrity transcription, regulating effect on antiinflammatory and immune system functions, induction of cellular apoptosis and signaling systems, responsive genomic action to different stimuli and some multiplicative physiological actions like inducing tumor growth, colon mutagenesis, retardation on blood vessel metastasis, inducing enzyme detoxification. The anticancer property of polyphenols could also exhibit epidemiological activities such as activating androgen receptor scavenging prostate cancer cells, stimulating response of mRNA for

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effective induction of cell death, reducing telomerase activity at the end of the chromosome to prevent the programmed cell growth. The polyphenolic content having high efficiency for anticarcinogenic activities include epigallocatechin-3-gallate, resveratrol, gallic acid tea sources, nonflavonoids anthocyanins, tannins, coumarins, stilbenoid derivatives, terpene complex, anthocyanidins, etc. Food waste can also be converted into bio commodity chemicals and form of bioenergy through undergoing an acidogenic fermentation mechanism and offer an alternative source of fossil fuel-based chemicals. The production of bioelectricity can also be governed by the excessive electrons of food waste sources which simultaneously remediate waste generation. Apart from acid-assisted processes, the framework of food waste bio-refinery has been constructing through other processes such as biodiesel production, electro-fermentation and solventogenesis. Sustainable green fuel like hydrogen can be produced from food waste using bio-photolysis, photo fermentation, and aerobic fermentation process. Composite vegetable market waste and food waste generally contain a large number of degradable organic materials and therefore possess a net value of positive energy which can be an efficient source to produce bio-H2. The utilization of food waste for energy sources is highly multiple advantageous as it is a very simple operational process, non-sterile, economical operating conditions, utilization of carbon-rich substrate with easy scale-up and process controlling nature. The pilot plant production of biofuel proceeds through combining the dark and photo fermentation process of food waste beverages. Reviews of the literature have also formulated the production of biohythane from food waste. The composition of biohythane can be represented as a 1:4 form of CH4 and H2. It is an appropriate bio-fuel for transportation media and having good calorific efficiency [9]. Volatile fatty acids are short carboxylic acids and produced from the food waste through anaerobic fermentation, which will depend on temperature, organic loading rate, composition, inoculums and redox reactions. The use of food waste effluent as biofertilizer is an integrated sustainable approach towards waste management. The liquid waste of food processing industries has evaluated the presence of degraded organic matter and microbial biomass, which are helpful to improve the soil fertility rate and divert the negative footprint of carbon additives into nutrient-rich organic fertilizer. The calorific values of FW are 5.35 MJ/Kg, which signifies its potentiality as feedstock to harvest bio-energy [10]. The integrated biorefinery platform obtained from the sufficient utilization of food waste will address the future perspective of bioeconomy and process optimization to get efficient integration, separation of the products, scaling up integrated technology and simultaneously scrutinizing the ideal approach towards minimizing the food waste disposals.

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6.2 Types of food waste Food waste is generally a rich source of natural biomolecules such as crop waste are the backbone of different pharmaceuticals, enzymes, solvents, surfactants (from oil-producing grains), lactic acid, carbohydrates (from vegetable waste), polymeric starch-based compounds, lubricants (from agro-food sectors), cellulose, hemicellulose (from fruit waste), bioactive potential antioxidative disease inducer phytochemicals like polyphenols (from tea waste) and different bioactive chemical skeletons. The wastewater stream of food processing industry contains organic constituent of non-biodegradable fatty acid residues. The composition and constituent verity of food waste include the carbohydrates, lipids, proteins and trace amount of inorganic compounds [11]. The poly-phenolic compounds include tannic acid, flavonoids, stilbenes, tannins and lignans. (Fig. 6.1). Over the decade, industrial food waste processing treatment has become more stringent perspective through the separation and purification process of semi-permeable adsorption and diffusion mediated membrane barriers. Secondary treatment of membrane bioreactor for total suspended solids (TDS) and biological oxygen demand (BOD) with limited functionality, low pressure-driven membrane recyclability of effluent discharge like micronutrients, pharmaceutical active compounds under tertiary processing have attracted tremendous multi-functionality from the regulatory and permitting side of waste management. Food waste is a general consequence of everyday life practice. Generally, tea waste is classified into two classes depending upon the chemical

FIG. 6.1 Schematic diagram of different types of food waste and their potential bioactivity. No permission required.

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nature of by-products and they also contribute several effects on the environment. Therefore, the tea processing industry contains the fiber portion of discarded tea leaves having one of the most important limiting factor tannic acids, which are the multifunctionalized key materials of antibacterial, anti-enzymatic and astringent properties [12]. Another tea waste is decaffeinated tea waste, which can be usually generated from the extraction of tea caffeine. Improvement of serious threats to the environment is mainly due to the exponential growth of food waste. The food waste biomass from agricultural production has carried out an unprecedented risk to human health, water bodies and public health [13]. The peculiar composition of agrofood processing waste has been recognized as a source of renewable energy, high potency towards biorefinery with sustainable evolution of food and chemical energy. The nature of food waste and its biological impact on the environment can inform the various parameters to treat and manage the waste effluent during food processing and storage. These parameters mainly include pH, temperature, dissolved oxygen, sulfur, oil and grease, nitrogen, phosphorus, biological and chemical oxygen demand [14].

6.2.1 Apple manufacturing industries The important waste of apple manufacturing industries is pomace and its extracts. The waste generated from this type of industry is a heterogeneous mixture of peel, seed with a higher amount of soluble and insoluble cellulose gradients, lignin and carbohydrate verities. The 25% wastage portion of apple industries is mainly pomace. The chemical composition of pomace byproducts represents the source of carbohydrates including glucose, fructose, sucrose, proteins, vitamins, crude fiber, minerals and several sources of nutrients. Although a million tons of wastes are generated from apple processing industries, the peel portion of an apple contains a higher quantity of phenolic compounds and therefore can contribute to the prevention of cardiovascular disease and also exhibit antioxidant activities. Undergoing drying and grounding processes, the waste peel can be used for the production of valuable food ingredients [15]. The antioxidant activities of apple peel waste can be evaluated due to its effective action against the oxidation of unsaturated fatty acids, lipid oxidation which can give quality assurance to consumer health. Using drying technology, the pilot-scale treatment of apple peel was also evaluated by determining the water retention capacity, dispersibility, and solubility index. Therefore the apple processing waste could be considered as the source of natural valuable food gradients.

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6.2.2 Berries A variety of berries such as blackberries, raspberries are used in the different process industries like jam, jellies and juice. The number of polyphenols, flavonoids and higher doses of fiber content is an important challenging substance which are higher amount of wastes generated from the manufacturing industries. The natural CO2-based supercritical fluid extraction method is used as the most promising technology for the recovery of valuable compounds in light of the less expensive and environmentally benign solvent-free extraction method [16]. The pomace of raspberries can be used for the production of cookies, which can increase the dietary fiber content and provide a positive influence towards organoleptic characteristics of product verities. The large amount of waste generated from the citrus food industries contains their seeds and peel portions. They can be used under the production of different cookies and sausage through undergoing variable concentration gradients and can balance the dietary fiber content level. The liquid waste of orange juice processing industries is a valuable source of citrus fiber. There is some reported literature, which evaluated the physicochemical and microbiological properties of liquid waste obtained from orange juice processing industries. The fiber content of orange juice waste has contributed their attribution towards a replacement of insoluble fats in ice cream derivatives [17]. Other important by-products of citrus fruit are citrus peel liquor, citrus silage, fresh dried pulp, citrus meal and fines, citrus molasses, and citrus activated sludge. The waste peel of exotic fruit process industries is rich in several biochemical properties, and these can be used as pectin. The acid-assisted extraction of pectin is used as a gelling and stabilizing agent for food coloring purposes. An acid such as nitric acid is used for the extraction process. The pineapple steam is waste liquor obtained from the pineapple processing industries. This waste stream can be extensively used for important enzyme extract like bromelain production [18]. The Mango seed kernel is an important by-product of mango juice processing industries. They contain total phenolic compounds, unsaponifiable matter, lipid contents and a source of crude protein. The mango seed kernel and extracted oil from it can exhibit antioxidant and antimicrobial activity in different food additives [19]. The powdery form of mango peel can enhance the nutritional quality, sensory and nutraceutical characteristics of food products. The by-products of coconut food industries are coconut skim milk and insoluble proteins. They are used as emulsifying agents and fillers in natural rubber. Papaya processing waste has shown important potential applications to food and beverages.

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Food industries are also producing a large amount of vegetable waste, which includes one of the important commonly consumed vegetable potatoes. The potato processing industry produces potato peel as the major by-product, which is the sufficient content of carbohydrates, vitamins, minerals and some phytochemicals such as carotenoids and natural phenols. The potato peels exhibit antioxidant property through retarding the protein and lipid peroxidation. The reported literature have also compared the by-products obtained from tomato processing industries. The main constituent of tomato processing waste stream is carotene, terpenes, tocopherol, steroids, and other polyphenol compounds. The tomato waste peel is characterized in terms of macronutrients including carbohydrates, proteins, insoluble sugars and fiber [20]. Several pieces of literatures have carried out the enzyme-assisted extraction of lycopene and carotenoids from the peel of the tomato processing waste. Supercritical extraction of lycopene is greatly enhanced by the seed containing tomato peel waste. The main by-product of the olive food processing industry is olive pomace. It is a solid residue and its major ingredients are found to be polysaccharides, fatty acids, polyalcohol, polyphenols and pigments. Therefore, waste generated from the storage of olive oil evaluated the presence of phenolic acids, lignans and flavones. The solid waste generated from the two-phase extraction of olive oil requires the hydrothermal treatment to disintegrate the soluble mixture of oligosaccharides [21]. Waste stream recovery of by-products focuses on their functional aspects including the production of biologically valued metabolites and fine chemicals. Proper utilization of these waste effluents is carried out by using gel filtration coupled with membrane-based techniques. Dry olive mill residue obtained from oil processing industries produces a higher extraction yield of hydroxytyrosol and phenolic components. Reported studies have carried out the extraction of oleuropein and hydroxytyrosol from olive by-products [22]. Broccoli by-products are considered a source of bioactive ingredients. These wastes are designed as novel beverages within the green tea food matrix and possessing characteristics of photochemical properties and improved physical quality [23].

6.3 Process for recovery of waste products The preservative food processing techniques are not suitable and sufficient enough on the need of demanding era of industrialization and there will be a prospect of uncontrolled emission of effluent aggregate food discharge. The features of food waste generally include their high organic content, salinity, oil and moisture content. The commercially available food waste treatment methods include incineration, landfill, anaerobic digestion, heat moisture reaction and composting [7].

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The anaerobic digestion process is used to produce methane as the main product and results in fertilizers as by-products. This process is costeffective having time-consuming fermentation [24]. The anaerobic method of methane generation is one of the foremost challenging and widely used food waste management techniques for the production of renewable energy sources. This method is of low cost and special characteristics of low residue production. The processing frequency of this process is accompanied by the series-wise steps of enzymatic hydrolysis followed by the production of acidic and gaseous products [25]. The acid genesis of food waste is mainly attributed to their transforming route towards gaseous substances including methane and carbon dioxide, which were further used as the source of gas adsorbents in various chemical estimations [26]. The enzymatic hydrolysis of food waste is initiated by the relative concentration of waste substrate, pH, temperature and bacterial concentration along with the productivity rate of enzyme adsorption on the waste surface. Land-filling is the widely available traditional treatment of waste which is highly disadvantageous due to the requirement of larger land area and superiors’ emission of greenhouse gas. The removal of bacterial contaminations and odors from waste materials can proceed through a heat moisture reactive platform [27]. A large number of organic components are present in the food processing waste which is the raw materials for conversion of energy in the form of electrical and other sustainable energy sources. The management of food waste disposal from different food industries includes various types of processes like enzyme-assisted separation, centrifugation, oxidative extraction, bioreactor application, flocculation, electrocoagulation processes. Membrane separation processes using ultrafiltration, nanofiltration, microfiltration and reverse osmosis have been applied due to their easy operational steps, highly efficient separation process and better productivity without phase transfer. Polymeric compounds of different molecular sizes could be concentrated and separated by multistage variable pressure-driven membrane processes for stabilizing sustainable industrial growth of food waste recovery [28]. There is also a recovery of phenolic compounds from agro-food-based industries. The phenol compounds from agro-food waste industries have been estimated followed by a qualitative fractionation process using ultrafiltration and nanofiltration membrane [29].

6.4 Extraction of food waste 6.4.1 Extrusion process This process is widely used in the food industries for oil extraction (viz., extraction of oil from olives, cocoa butter, oleaginous seeds), concentration in dry matter (important wastes of food industry like sugar pulp) extraction of juice from fruit additives, grapes and tomatoes.

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Offiah et al. have briefly outlined the recovery of raw food and by-products using processed extrusion. Vegetable oils are a valuable class of bioresources. The different extraction processes can determine the quality of the oil. Thermo-mechanical pressing of oil seed processing industries is very much interested in a sustainable environment [30].

6.4.2 Solvent extraction The bioactive compounds present in agro-based food industries can be recovered and easily reused through conventional extraction processes. The coloring substances like anthocyanin obtained from different solvent treatments of raw waste can be very much effective towards cancerous and inflammatory actions. Solvent extraction is one of the important extraction processes for the recovery of polyphenolic compounds from food and vegetable wastes. In this process, the food wastes are dissolved in organic solvents and after that, the mixture is centrifuged and the precipitate is collected through removing solid residues and filtrate can be applied as an additive to food supplement and functional food. In this method, the solvent is used to facilitate the higher yield of extraction and therefore the compounds can be extracted by evaporating or concentrating the solvents. Reported studies have revealed that the extraction of lycopene and beta carotene was obtained from tomato pomace using ethanol [31]. The use of water in the solvent extraction process is one of the effective ways for extracting the compounds. The basic criteria of water include that it is non-flammable, non-toxic and environmentally benign. Therefore, it can provide clean processing and preventing pollution during the extraction process. Water has been used for the extraction of food and natural products from different processes and procedures: maceration, decoction, infusion, and percolation. To analyze the better extraction yield of conventional processes, solvent polarity is considered as an important factor, which significantly influences the plant matrix damage to isolate the targeted compound. The increase in polarity of polar compounds like polyols is carried out by using polar cosolvents like ethanol, methanol, acetonitrile, acetone, water, ethyl ether and hence induces the rate of extraction yield [32]. The extraction of phytochemicals is also affected by factors including temperature, time and solvent concentration. Literature survey reported that N,N-dimethylformamide and acetone are highly effective to extract the natural phytochemicals with a higher degree of accuracy [33].

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6.4.3 Sub critical water extraction It is an alternative environment-friendly technique for the extraction of valuable gradients from food waste. Mainly the lower time of extraction, higher yield and low cost of solvent are the advantageous steps to carry out the subcritical extraction of food waste materials. The subcritical extraction is highly quantitative on the extraction of polyphenols from mango peel compared to solvent extraction [28]. Chlorogenic acid and ellagic acid could be extracted from the potato peel waste at a temperature of 180°C and this extraction process act as a substitute for organic solvent. The supercritical fluid extraction process is carried out by a change in temperature and pressure gradient with the transformation of gas into a liquid. This process is used to isolate nonpolar bioactive compounds like carotenoids or lipids. The use of liquified petroleum gas as the supercritical liquid is very much necessary for the extraction of terpene from an industrial process.

6.4.4 Enzyme assisted extraction There is widespread use of enzyme-based extraction processes for the extraction of compounds from food waste. The tomato processing industries yield a fraction of its peel as the waste source and these can be extracted through the waste treatment with enzymes like cellulose, glucose, etc. and their extraction yields are modified by the use of mixed enzyme of cellulolytic and pectinolytic characteristics. This can improve the extraction yields under mild processing conditions [29]. The cell wall degradation rate and the depolymerization of the intercellular structure of waste recoveries act as a driving force of enzyme-based isolation of bioactive compounds.

6.4.5 Ultrasound-assisted extraction The ultrasound-assisted extraction process is also an important extraction process that can be applied to extract bioactive compounds from waste sources. This process is very much advantageous to induce a higher rate of diffusion of the solvent into the cellular matrices and hence improve the mass transfer frequency through disrupting the cell wall of compounds. Reported studies have evaluated the extraction of compounds including anthocyanin and phenols from grape peel extract and the progress of the reaction was controlled under an enzymatic environment. The winter melon seeds are also rich in bioactive compounds, which can be extracted using an enzyme-based process. The isoflavone

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derivatives like glycitin and genistin are generally found in the waste fraction of soybean and these can be extracted using mixed solutions of enzymes under different temperatures. From grape cane, the extraction of stilbenes is carried out using a validated and optimized ultrasoundassisted extraction process. Extraction of water-soluble polysaccharides from dried and waste products of different food industry sources can be obtained using an ultrasound-assisted extraction process. From mushroom by-products, the beta glucon like bioactive ingredients can be obtained at a specific weightage of 1.01 g using an ultrasound-assisted extraction process [34]. An effective alternative of better extraction yield is the ultrasound-assisted extraction process, which grows and facilitates the passage of bubbles produced into the cavity or pores of organic– inorganic polymer matrix through the cavitation phenomenon. The versatile and flexible ultrasound-assisted process has been used for the isolation of biomaterials like polysaccharides, dyes, peptides, proteins, essential oils and pigments. Literature surveys have validated the use of this process on the suitable extraction of compounds from black chokeberry fruits, flavonoids, tannins and the class of polyphenols [35].

6.4.6 Microwave-assisted extraction This method is coupled with a normal solvent extraction process and it is highly sensitive towards extracting the biologically active compounds from matrixes of inner and outer cell structures. The shorter time interval of extraction is an important key point of this process compared to other conventional processes. It can be used as an effective alternative for the recovery of compounds from agro-food-based industries [36]. The microwave-assisted process is generally used for the specific isolation of bioactive complexes with successful diffusive penetration of solvent into a solid matrix. The solubility of a solid substance is determined by the applied microwave frequency and concentration is limited by solid characteristics [37]. The decrease in thermal gradient and effective diffusion rate of this process are driving forces to recover bio-ingredients from pharmaceutically important medicinal plants.

6.4.7 Pulse electric field This is a non-thermal technique with growing adaptability, shorter time of performance and possesses heating effect at a lower extent to extract the valuable components of food waste stream. Here, a highly tensed electric pulse is passed through the two electrodes and disintegrates the cell wall with reversible and irreversible formation of pores. Thus, electroporation facilitates the rate of mass transfer from vegetable waste and this process is

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a measurable technique for the recovery of compounds like carotenoids, anthocyanins and chlorophyll [38]. The electrical discharge of high voltage capacity can integrate with water extraction under optimized temperature to carry out the reclamation of protein and phenolic compounds.

6.4.8 High hydrostatic pressure extraction This process is widely used to retrieve bioactive compounds including pectin extract of orange peel, anthocyanin from grape seed, lycopene and carotenoid gradients from tomato waste under variation of organic solvent. Concentration gradients followed by diffusivity are important aspects of this process to enhance the cell permeability on strengthening the rate of mass transfer. The process is controlled by the immense effects of physicochemical parameters like temperature, time, solvent, pressure, etc. Reported studies have evaluated the recovery of flavonoids and total phenolic compounds from grape by-products under competent temperature and pressure [39]. Cost-effectiveness plays an important role in this process to get a higher extraction yield. The economic and sustainable recovery of intracellular valuable compounds from food materials, different vegetable materials are carried out by pulse electric field assisted extraction process, where softening and disruption of a plant cell membrane is a characteristics parameter for electro-operation of targeted compound species. High pressure can induce the disruption of the cytoplasmic cell membrane to recover and isolate phenolic antioxidants. This high voltage electric discharge can directly introduce into the aqueous solution through a plasma channel [40]. The physicochemical, nutritional property of bioactive constituents can be stabilized with secondary metabolite diffusion with effective rate of mass transfer. The generated high hydrostatic pressure can lead to deprotonation of charged groups with simultaneous disruption of hydrophobic interaction and salt bridge formation [41]. This treatment is generally used for the extraction of anthocyanine from apple with cell permeabilization of selective mass transfer rate. The estimated rate of applied high pressure at ambient temperature can also affect the concentration of bean protein [42]. Partition chromatography is one of the leading approaches to isolate phytochemicals from crude extract using ion exchange resin.

6.4.9 Membrane assisted extraction The membrane processes have attracted very much importance for isolation and concentration of nutrients from food processing industries. Several polymeric membranes are used for the separation process due to their lower rate of energy consumption and higher retaining ability of

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substances. For an effective separation process, an alternate approach like reverse osmosis (RO) can be used for the fractionation of liquid products obtained from food waste. Polystyrene-based microfiltration membranes are used in the form of hollow fiber to treat the sedimented waste and filtrate can be extracted as permeate. Using this process, numerous bioactive compounds like pectin, amino acids, carbohydrates can be isolated from the food processing stream under variable temperature and pressure. These particles can be entrapped inside a porous microfiltration membrane and this is advantageous over an ultrafiltration membrane. Asymmetric polymeric membranes are generally fabricated through different modifications and can be used for scale-up processes. Therefore, polymers like polyimide, polyacrylonitrile, polyethersulfone, polypyrrole, polyarylenesulfide sulfone, and polybenzimidazole membrane are embedded with dense selective layer supported by a microporous structure. The membrane performance can be evaluated through the cross-linked polymeric network for effective permeation of solid and liquid waste depending upon the molecular weight cut off of the membrane. Molecularly imprinted membranes are used for enhancement of size exclusion behavior of membrane. The membrane-based separation processes are concerned with the organic solvent medium and the use of metal–organic frameworks to isolate bioactive compounds from food waste. The composite organic–inorganic matrix can be designed like mixed matrix membrane of the polymeric skeleton and which can widely possess chemical and mechanical stability to overcome flux decline on the treatment of food waste disposal. Anaerobic membrane bioreactor (AnMBR) is a combination of anaerobic bioreactor equipped with membrane filtration. The use of an anaerobic membrane bioreactor is an efficient promising technology for the treatment of wastewater generated from food processing industries. The treatment of food waste on membrane bioreactor is very much essential to remove their organic micro-pollutants. The extent to which this removal frequency will depend is maintained by the chemical phenomena like sorption into biomass followed by transformation and membrane filtration. This process is highly advantageous towards the removal of waste disposal from process industries because of their uncouple rejection time and solid retention time. Therefore, the production of bio-energy in the form of methane gas is an important key step of AnMBR. Sorption and biotransformation play an effective role in the removal of organic micropollutants from food processing waste. The different porous membranes like NF and UF are used in membrane bioreactors to retain the biomass from wastewater. The granular activated carbon and powdered activated carbon are used as fluidized media in membrane bioreactor to degrade the organic micro-pollutants from waste disposal. This can remove dissolved oxygen from the liquid stream of food processing waste to reduce the

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quantified value of BOD and suspended solids. The permeate fraction of MBR shows quality products with a low concentration of organic matter and suspended solids. Membrane technology is indeed a most promising platform for controlling the efficient energy consumption, optimization of capital cost, conservation of environmental impact, design of innovative products in agro-based food industries, enhanced product quality of waste foodstuffs to give a better opportunity for exploring the potential industrial sustainability to uphold the global economy. Volatile fatty acids obtained from the food processing waste are valuable ingredients to obtain biogas. They are obtained from the anaerobic digestion processes. The anaerobic digestion process is applied to produce biogas. The stepwise formation of biogas includes four steps of the biodegradation process namely hydrolysis, acidogenesis, acetogenesis, and methanogenesis. In the AD process, the promising recovery and production of VFA involve the treatment of solid organic waste using immersed membrane bioreactor and therefore they can inhibit acidic influence and can enhance the biodegradation [43].

6.5 Recovery of bioactive compounds from waste The vegetables and fruit by-products include leaves, seeds, bark and peel and their edible parts are found to be antioxidant active. Before going through the extraction process, the waste products are treated with preliminary processing steps. The fruits and vegetable by-products are widely used to recover pectic polysaccharides and hence it can exhibit the food additive power with its biological availability [44]. The pea pod extract of glycosaccharides is composed of xylose, arabinose and galactose on high methylation. The ultrafiltration process is highly efficient towards the purification of pectin extract from fruit by-products and the beta glucon from the cereal by-products. Rice brains are obtained as waste materials originating from the food processing industries and they are found to be composed of nutraceuticals complexes as well as anti-oxidant active substances. Food processing waste is mainly originated from the end products of different process streams and they have been recycled and can be used for other purposes to preserve their nutritional aspects towards a sustainable environment. The chemical components of food waste are mainly classified under organic materials including lipids, carbohydrates and proteins. Suspended solids are also important bio-waste depending upon their source of production and consumption. The raw composting nature of food waste is a unique characteristics property. The high moisture content of composting waste can be reduced through mixing out with bulking

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agent to absorb the successive amount of moisture and give structural improvement to waste. The high C:N ratio of bulking agents provides water quality and agricultural concern to the composting waste source [25,45]. The beneficial effects of compost on the food processing industries include the reduction of loss of recyclable ingredients obtained as end waste, the disintegration of food waste loop and recovery to the agricultural field.

6.5.1 Adsorption The adsorption process is one of the important separation mechanisms in the framework of food waste recycle and recovery. The basic principle of this process is mainly involved due to the transfer of components from a liquid phase to a solid adsorbent material. Solid adsorbents like zeolite, resin, activated carbon, lignin, clay can be used to carry out the adsorption of food waste components present in the liquid stream [46]. Selective adsorption of value-added chemicals obtained from food industries is easily analyzed through molecularly imprinted polymers. These types of polymers are functional microparticles having variable size, shape and reactive surface compared to the template molecules. Selective extraction of targeted species is carried out from the agro-based industrial liquid waste.

6.5.2 Electrodialysis The concentration and recovery of lactic acid from food waste fermentation broth are carried out by the electrodialysis process. The bipolar membrane process is an efficient route to initiate the separation of lactic acid components. This membrane is composed of a laminated cation exchange layer overlapped with an anion exchange membrane surface. The dipolar ions of water molecules are involved in the force of attraction with lactate anion and sodium ion and thus formed lactic acid and NaOH separately and therefore can be recycled to fermentation tank without undergoing any chemical treatment [47]. The removal of colloids, particles and other cells from lactic acid waste is also recovered at the pilot-scale level. In juice processing industries, the chemical composition of the process stream is mainly attributed to the presence of starch, cellulose, pectin, protein, hemicelluloses. Due to the time-consuming laborious traditional methods of controlling the juice waste, the technology has gained their perspective applications to the treatment of fruit processing waste materials. Therefore, the ultra-filtration separation barrier is applied to clarify the fruit juice like pineapple, grapes, citrus, pears. During membrane-based

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treatment of juice waste, the higher flux value can be obtained from the enzymatic depeptization of juice with reducing their viscous fluidity [48]. For cost-effective distribution and storage of juice, the juice is concentrated followed by pasteurization and the concentration process may lead to the loss of aromatic counterparts from the juice mixture through vacuum evaporation. On induction of distillation column adjacent to the vacuum evaporating channel, the aroma compounds can be recovered and stored at a relatively higher temperature to get the better yield of the product with enhanced quality [49]. The use of reverse osmosis membrane has retained a higher number of aromatic compounds eluted from the food stream. The increase in retention of aroma over membrane surface is due to the reactive polyamide inter-linkage over their surface. With the use of potato as a raw material in the process industry of fruit juice, a large volume of wastewater is obtained along with the fraction of potato juice. The general chemical composition of potato juice is 0.5% starch, 2.4% protein crude, 0.1% fiber, and 0.4% glucose content. The total solid content of potato juice is around 5.5% which is a combined composition of both crude protein and nitrogen compounds and they have a higher consumable rate for the entire ecosystem [50]. Therefore, microfiltration membranes are used to remove the microbial contaminations from the crude protein of potato juice under ambient temperature and controlled trans-membrane pressure. The protein solubility under optimized conditions can bring out their functional properties with high nutritional value. Recently, the food processing industries and food waste have gained considerable attention towards a replacement of petroleum fuel through the production of bio-ethanol and bio-butanol. The process stream of bio-butanol production includes the use of food waste, food grains, food crops, lignocellulosic materials, algal biomass, and food processing wastes [51].

6.6 Potential applicability of food waste The potential applications of food waste include the production of nutraceutical, pharmaceutical and biological derivatives. The waste section of food like seeds, peels contains an enormous number of carotenoids, phenolic compounds and polysaccharides and therefore they can be used as antibacterial and antioxidants, flavoring and coloring agents in the food processing industries. Besides food waste extract to the verities of production factories like bakery, meat and dairy can improve their nutraceutical properties. Introduction of dietary fiber-rich fractions of food waste on the process stream of different food industries can selectively optimize the fat and sugar content of foodstuff. The stem and peel portions of onion waste

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are sufficient enough to exhibit their antioxidant and antibacterial value on the consumption of foodstock. Nutraceutical action of food waste additives is an important phenomenon on the demanding health concerned activities. The modulation of the immune system, cardiovascular drug and serving as antioxidant agents are widely controlled by the pigment of carotenoid and lycopene obtained from the food processing system. The fruit waste bi-products have estimated the presence of poly-phenolic aggregate like resveratrol and possess their biological activities like disease concerning antioxidant and antibacterial activity [52]. The therapeutic action of mango kernel extract, peel and skin layered portion of mango and guava products are an essential source of waste to minimize oxidative stress-related diseases. The peel and seed parts of different crop verities like banana, mango, jackfruits, coconut, potato, germinated rice exhibits antimicrobial and anti-allergic properties. The studies of reported data aim to focus on the wastage portion of potato peel, which is an excellent source of alkaloid verity having anti-inflammatory and antihypertensive traits. The waste products can also be applied for the coloring purpose of food additives. The carotenoid pigment of lycopene present in tomato peel is applied to the coloration of ice cream and butter. The burning impact of UV radiation and inflammatory erythema on flora and fauna can be minimized using cosmeceuticals discrete peptide sources of food waste by-products [53]. Coffee waste in the form of a cream has been used to reduce the aging gap of human skin and exhibit a negative toxic impact on keratinocytes.

6.7 Conclusion The recovery of nutraceuticals food waste has been carried out as a challenging task to reduce the worldwide pollution of generated waste. The presence of bioactive compounds, dietary fibers, proteins, and carotenoids has imparted important biological advantages of food waste sources [54]. Therefore, their pharmacological and nutraceutical activities have been examined through different conventional extraction techniques using variable physicochemical parameters. The isolation and concentration of nutritive food gradients from the waste stream are essential key steps to bring out the environmental equilibration. Several fermented technologies have been widely used on reclamation of the food waste additives to improve the quality control rate of wastage parts and prevail their biological impacts on the disease-causing microbes. Green and viable isolation techniques applied for food waste recovery are very much advantageous to retain their behaviors against different application fields. Therefore, the consumer demand is more for the recovery and recycling of

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food and vegetable waste using various processes to stabilize environmental sustainability. The reduction of processing time and environmental destruction, improvement of extraction yield, the use of sustainable green membrane approach become a very much significant methodologies for the recovery of biologically benign products from food waste resources. In the context of the worldwide scenario of synthetic methodologies, the recovery of nutraceutical ingredients through developing analytical procedures is summarized in this chapter.

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C H A P T E R

7 Waste incorporation in glass: A potential alternative and safe utilization Ashis Kumar Mandal, Sourja Ghosh, Barun Haldar, Sourav Nag, and Sitendu Mandal CSIR-Central Glass and Ceramic Research Institute, Kolkata, India

7.1 Introduction 7.1.1 Tannery solid waste (TSW) A large amount of solid wastes is generated by the tannery industry during various stages of the tanning processes of raw hides and skins and the processing of leather involving pretanning, tanning, post-tanning and finishing processes, and wastewater treatment. Treatment of such wastes is very crucial due to the presence of various toxic and hazardous constituents, such as chromium; if not adequately treated, the disposal of such wastes can cause considerable damage to the soil, surface and groundwater, and also the atmosphere with the emission of toxic greenhouse gases. Tannery solid waste (TSW) falls under a “red” category due to its high environmental damaging potential. It constitutes raw hide trimmings and wastes, unused salts, acids, lime pit sludge, sulfides, fleshings and trimmings, hairs, chrome shavings and trimmings, dyes, pigments, binders, crust leather, sludge from the pretreatment process, buffing dust, etc. [1]. The toxic effect of leachates produced from TSW on the growth and reproduction of Drosophila was analyzed [2]. At high concentration of the leachates, a significant inhibitory effect was observed on the growth, as well as on the reproduction behavior of the flies. It was concluded that TSW leachate can potentially affect the gene expression controlling the seminal proteins that contribute to normal reproduction.

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Due to the low cost, proteins in TSW are concentrated and used as an ingredient in poultry feed. The presence of chromium and other heavy metals were analyzed in poultry feed derived from tanned skin cut wastes and the edible parts of the chicken consuming the feed [3]. The study showed substantial heavy metal accumulation in the various edible parts of the chicken, i.e., chromium (0.1–2.44 mg/kg), lead (0.257–1.75 mg/kg); and cadmium up to 0.037 mg/kg, indicating significant concern for the accrual of these heavy metals in humans through the food chain. 7.1.1.1 Various approaches for TSW management About 145–193 tons/day of TSW is produced in the various processes of leather processing, corresponding to a production capacity of 100 tons hides/day [1]. TSW is rich in nitrogenous and organic matter, hence composting has been used by various researchers for environment-friendly management of such wastes. Due to the acidic nature of TSW, prior neutralization was done with ammonia and lime, respectively, and the various properties including humid acid formation was analyzed in the raw and composted product obtained [4]. Application of lime-based neutralization was proven to be more complete, and the process was proposed as a cost-effective way of TSW management. A major part of TSW involves fleshing, which consists of protein, fat, and hairs along with associated chemical agents like lime, alkali, and sulfides produced from the unhairing and liming processes of the beam house operation. Further, the wastewater treatment processes of tannery industries produce a large volume of primary sludge from the physicochemical treatment of wastewater and waste-activated sludge from the biodegradation/activated sludge-based biological treatment processes. The volatile solid-rich TSW was subjected to anaerobic digestion with an aim for technology development for bioenergy recovery, as well as safe disposal of TSW [5]. About 71%–77% methane yield was achieved. Further, fleshings and the primary and secondary sludge of TSW was used in a codigestion process to investigate the bioenergy production potential by optimizing the substrate mixing ratio. The study revealed high prospect under clean development perspectives involving about 52.15  106 kWh/year of bioenergy creation for the Indian tanning industry, having 700,000 t/a of processing capacity along with reductions of greenhouse gas emissions up to 0.3  106 t CO2-eq/year [6]. The solid waste management of the tannery industry involves isolation and extraction of raw materials for different product generation such as glue, gelatin, and animal feed [1]. The tallow produced from green fleshings is used for cosmetic product manufacturing. After collection and processing, the hair and wool are used in carpet manufacturing and fertilizer production after hydrolyzing [7]. A portion of thermally and chemically denatured fleshings obtained from the tanning process is not suitable for glue production,

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and thus, disposal into a landfill is practiced for such wastes, which causes severe environmental concern [1]. Pyrolysis and incineration were considered as prospective treatments and disposal aspects for chrome-tanned TSW and chrome shavings from tanning units. The process showed a necessity for off-gas treatment due to the high extent of gaseous emissions. It had been concluded that the conversion of trivalent chromium present in the residual ash to hexavalent chromium could be a prospective raw material for synthesis of sodium chromate or other ferrochrome alloys in the chemical/metallurgical industry [8]. A green process was proposed involving activated charcoal-induced treatment of yellow sodium sulfate contaminated with sodium dichromate, which is a hazardous by-product of the leather chemical industry, wherein the toxic Cr+6 could be converted to a less-toxic form of Cr+3. The process resulted in production of pure sodium sulfate and Cr+3 residues in separated forms, which could be recycled for respective applications [9]. Stabilization of chromium-rich tannery sludge in clay brick products can be an effective option. Up to 40% of TSW was incorporated in clay brick preparation, and various properties such as strength, bulk density, shrinkage, water absorption, etc. were analyzed to assess the applicability of such a process as an energy efficient disposal strategy [10]. The prepared bricks achieved both the Bangladesh and American Society for Testing and Materials (ASTM) criteria defined for construction material. The incorporation of TSW showed savings of energy up to 15%–47% in the brick firing process. Leaching study revealed no significant leaching of heavy metals such as chromium, copper, arsenic, lead, cadmium, nickel, and zinc, indicating the prospect of the process as a sustainable alternative for TSW management in building material production in Bangladesh. Aerobic stabilization-based pretreatment of TSW was proposed as an alternate option for disposal in landfilling [11]. Compaction followed by drying of the sludge resulted in biostabilization with mass and volume reduction. The process showed less leaching of various organic and inorganic constituents, thus usable as a prospect for sustainable disposal of TSW in landfilling and achieving a state of carbon sink. The protein-rich TSW obtained from the fleshings, trimmings, and shavings of the skin/hide contains various functional groups, thus the adsorption potential of such wastes was explored for removal of toxic contaminants like metals and dyes in an aqueous phase. Cattle hair waste from the tannery industry was used to prepare a new biosorbent and was employed for acid dye removal in an aqueous system. About 104.78 mg/g of adsorption was obtained for acid blue dye, while for acid black dye this was 26.29 mg/g [12]. The dried activated sludge of the tannery industry was utilized to develop a complex biosorbent. The adsorption efficiency was evaluated with respect to various heavy metals such as nickel, cobalt, zinc, and

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cadmium [13]. In addition to the removal of heavy metals in synthetic systems, the biosorbent could successfully remove such metals (>96%) in the industrial effluent of battery manufacturing units along with simultaneous removal of lead, copper, and iron. Further, the metal-loaded exhausted biosorbent was immobilized in a phosphate glass matrix as an innovative safe disposal strategy. X-ray powder refraction (XRD) analysis of prepared glass sample showed inertization of the metal-laden biosorbent up to 30%. Significantly, the leaching study conducted with the glass samples for 8 h/day up to 35 days revealed heavy metals were not leaching with a thermal cycle of 75°C.

7.1.2 Arsenic-containing sludge (ACS) The existing methods for arsenic removal from water such as adsorption, coagulation, chemical precipitation, membrane separation processes, and others used in the water treatment plants produce a large volume of ACS, and its safe disposal becomes a serious issue. About 5–7 kg of arsenic is found per cubic meter of ACS, which can potentially cause environmental contamination due to the strong possibility of arsenic leaching [14]. Hence, immobilization of arsenic in inert matrix such as concretes, bricks, ceramics, and glass substrate can be a solution toward safe disposal of such toxic sludge in the long term. Apart from solidification, acid extraction, vitrification, and pyrometallurgical recovery can be used for treatment of ACS [15]. 7.1.2.1 Various approaches for ACS management Stabilization aspect of ACS in bricks was investigated by mixing the sludge in various concentrations with cement concrete and clay soil [16]. The compressive strength and leaching behavior as per the toxicity characteristics leaching procedure (TCLP) of the prepared concrete cubes and bricks were measured. Further, the ACS was inserted into an anaerobic bioreactor to observe the stabilization. Arsenic concentration in the leachate was observed to be within permissible limits, thus cement concrete and bricks could be an environment-friendly option for ACS stabilization. Ferric salt and aluminum salt involving ACS obtained from an arsenic-contaminated drinking water treatment plant was studied after solidification in Portland cement for the leaching effect and associated toxicity [17]. The leaching toxicity was observed to decrease about 90% after the solidification process. The prepared products satisfied the requirement for the landfill and sludge retrieval in terms of the compressive strength. Moreover, inclusion of the ACS containing ferric salt resulted in enhancement of the compression strength of road application concrete. The prospect of utilization of ACS with nonferrous industrial residue

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involving primary lead zinc smelter was studied in construction material preparation by mixing with cement clinker and limestone [18]. At an optimum condition, the unconfined compressive strength was achieved as 9.30 MPa, and a safe level of leaching of arsenic (90% of waste glass or more in the process of developing glass products thus saving natural resources (i.e., raw materials). Waste glasses are often varying in composition due to contamination making it difficult to reuse for its original use. Sometimes, it is found as a mixer of glasses from different component/devices limiting its application in landfilling only. One of the objectives of the present proposal is to develop lightweight porous glass foam suitable for construction, insulation, and soundproof application from waste glasses.

7.2 Material and method 7.2.1 Glass preparation with TSW TSW is collected from the tannery industry located in Kolkata. The collected TSW is then washed and dried. The dried TSW is mixed with a suitable batch composition for glass preparation. The composition was

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optimized with waste loading up to 15 wt% of dried TSW. The batch containing TSW is sintered at 300–500°C for 2 h to remove organic impurities as well as moisture and the gaseous component from the raw material. The batch is melted in an alumina crucible in a resistance heating furnace within a melting temperature (1300–1400°C) depending on the composition of glass. Melting parameters including stirring condition are optimized to obtain good glass. The melt is cast onto a preheated metal mold of the desired shape and subsequently transferred into a muffle furnace for annealing. The obtained glass is processed using cutting, grinding, and polishing to have the desired dimensions of glass block. Usually, small glass block of dimension 10  10, 10  15, or 25  20 mm is prepared with a thickness of 2 mm to measure the UV–Vis–NIR spectrum.

7.2.2 Glass preparation with ACS ACS was collected from the water filtration unit developed at CSIRCentral Glass and Ceramic Research Institute. The generated/collected ACS is dried and mixed with a suitable batch comprising different raw materials for glass melting in a resistance heating furnace followed by optimization by the melting parameters. Maximum of 20% ACS is loaded with the batch. The melt is cast into a preheated mold and subsequently transferred into a muffle furnace for annealing followed by controlled cooling to room temperature. Glass processing is carried out adopting a similar process as stated earlier. Leaching characterizes of metal, i.e., As, Fe (from glass) has been performed under submerged water at a elevated temperature of 75°C for 14 days.

7.2.3 Glass preparation with e-waste glass Waste glasses from different sources (tube lights, bulbs, etc.) are collected and washed with water and dried. A small amount of glass is crushed and powdered followed by mixing with glass raw material. Waste loading was optimized based on the composition and its application. Up to 90 wt% is mixed with other ingredients to generate color in glass. Less than 1 wt% of cobalt is added to demonstrate blue color in glasses. A similar procedure was adopted for glass processing after casting and annealing. The mixed glasses with a wide composition variation are powdered and mixed with foaming agents such as Na2CO3, CaCO3, SrCO3, MnO2, etc. and sintered to generate gas bubbles and retain it in the glass by optimizing the glass viscosity. Foaming temperature will be varied within 800–900°C to obtain desired sizes of pores. Steps of glass preparation or preparation of glass foam are presented in the schematic in Fig. 7.1.

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Collection of waste glass

Segregation and water washing of glasses

Chemical analysis of different waste glasses

Batch preparation incorporating waste glass and optimisation of its loading

Optimisation of Melting parameter in resistive furnaces: 1300-1500°C

Sintering of glass with foaming agent to make foam glass: 8001000°C

Casting followed by shaping and annealing (characterisation)

Glass Foam (Characterisation)

Glass Article/Product development FIG. 7.1 Schematic of glass preparation using waste.

7.2.4 Glass preparation with RHA RHA is collected from a domestic source and sintered at 600°C for 2 h for oxidation of unburnt carbon present in the RHA; 20 wt% of RHA as received and sintered are mixed with waste glass cullet and melted in a resistance heating furnace at 1300°C for 1 h. Manual stirring has been adopted using a silica rod to improve glass homogeneity. Then, casting was carried out in a preheated mold and annealed in a muffle furnace as described in an earlier section.

7.3 Result and discussion

145

7.2.5 Characterization X-ray diffraction study is carried out on 94 X’Pert, PANalytical using ˚ from 10–90° to Ni-filtered CuKα radiation with wavelength of 1.5406 A identify the glass formation. Optical absorbance spectra in the visible region was recorded on a UV–Vis spectrophotometer (Model: Lambda 920, Perkin Elmer, UK) in the wavelength range 450–700 nm in glass containing TSW and in the wavelength range 400–800 nm for glass containing ASC. UV–Vis–NIR spectra of RHA-incorporated glass was recorded within 300–800 nm. Porosity and density of glass foam were measured. The density of glass is measured adopting Archimedes’ principle using water as buoyancy liquid on a Mettler Toledo balance fitted with density measurement kit with an accuracy 0.001. Porosity of foam glass is evaluated from the weight of glass foam with the measured volume of glass foam considering the bulk density of glass waste.

7.3 Result and discussion 7.3.1 Tannery waste incorporation Fig. 7.2 depicts X-ray diffraction profile of glasses melted incorporating 2–15 wt% of TSW in the batch. Absence of crystalline peak in the XRD profile indicates no unmelted crystalline phase (from TSW) with the glass. Varying TSW loading and glass composition color of glass was optimized.

FIG. 7.2

XRD profile of glasses prepared incorporating 2, 5, 10, and 15 wt% of TSW.

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7. Waste incorporation in glass: A potential alternative and safe utilization

(B) Transmittance (% T)

(A)

80

Glass with 10% TSW

60

50% T at 550 nm

40

20

0 450

500

550 600 Wavelength (nm)

650

700

(A) Polished glass block of dimension 65  50  12 mm prepared mixing TSW with the raw material. (B) Transmission spectra of glass containing 10 wt% TSW with the visible region.

FIG. 7.3

The glass is now placed in a shaped mold/ceramics mold to develop various glass articles. Addition of other transition metals may also be investigated to develop UV-transmitting property in glass. Polished glass block of dimension 65  50  12 mm prepared containing TSW is seen in Fig. 7.3A. Fig. 7.3B depicts transmission spectra of glass containing 10 wt% TSW within the visible region. It is clearly seen in Fig. 7.3B that optical transmission of 50% at wavelength 550 nm indicating application as green color glass. Optimization in glass composition with waste loading may be carried out to develop color filter glass.

7.3.2 Arsenic waste Fig. 7.4 displays glass containing 5, 10, 15, and 20 wt% of ACS. Brown color glass is seen with 10 wt% loading of ACS in the glass system. X-ray diffraction profile of glasses melted incorporating 5–20 wt% of ACS in the batch is presented in Fig. 7.5. Absence of crystalline peak in the XRD profile reveals complete incorporation of ACS into the glass matrix up to 20 wt%. Iron oxides present may be utilized to develop heat-absorbing properties in the glass owing to Fe[II] characteristic absorption at the near-infrared region. Fig. 7.6 exhibits UV–Vis transmission spectra of glass containing 5–20 wt% of ACS waste within the visible wavelength range. Transmission in the visible range falls flat at above 15% loading of ACS. Therefore, application of glass may be limiting to the waste loading up to 15 wt% of ACS. Arsenic immobilization in a glass system can be further investigated with higher waste loading.

147

7.3 Result and discussion

CSIR- Central Glass and Ceramic Research Institute

a

b

c

d

FIG. 7.4

Glass obtained incorporating ACS waste 5% (A), 10% (B), 15% (C), and 20% (D).

FIG. 7.5

XRD profile of glass melted with 5–20 wt% of ACS waste.

7.3.3 E-waste glass Apart from these hazardous wastes, various kind of less-toxic wastes are being generated in huge quantities including glass from e-waste, vehicle windscreens, and others. However, proper utilization of e-waste glass from these wastes in a scientific manner has not yet been initiated mainly

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7. Waste incorporation in glass: A potential alternative and safe utilization

FIG. 7.6 UV–Vis transmission spectra of glass containing 5–20 wt% of ACS waste. FIG. 7.7 Co-doped blue color glass prepared utilizing e-waste glass.

due to compositional inhomogeneity and impurity. Some unorganized sectors are working without evaluation of potential use of the waste glasses. Waste glasses vary with chemical composition, and therefore, one single application of all glass collected from different sources is not feasible. Therefore, waste glasses are mostly dumped into landfills. Blue color glass was prepared utilizing more than 90 wt% e-waste and doping with cobalt in glass as shown in Fig. 7.7. As this waste glass has no fixed composition, it varies with application and properties. Waste glasses may be used as cullet/raw material for new glass products as glass can be recycled/remelted repeatedly without significant change in its property. This waste glass can be utilized as cullet for

7.3 Result and discussion

FIG. 7.8

149

A photograph of foam glass (floating on water) produced from waste glass.

color glass making, and this glass can be used for decorative purposes. However, functional applications using this glass depends on the separation of various glasses. As the glasses lack any composition, homogeneity and vary from batch to batch and may find application in glass foam preparation. Fig. 7.8 presents a photograph of foam glass (floating on water) produced from waste glass. The foam glass density was measured as 0.40 g/c.c. with porosity 80%.

7.3.4 Rice husk ash (RHA) Fig. 7.9 depicts UV–Vis–NIR spectra of glass incorporating RHA. RHA as collected from domestic sources was incorporated, and the obtained glass was found to be brown in color as shown in the inset of Fig. 7.9. However, brown color could be eliminated using sintered RHA at 600°C for 3 h. Visible transmission can be significantly improved with sintered RHA due to the conversion of unburnt carbon. However, infrared transmission at wavelength 1000–1200 nm was reduced due to the presence of iron in Fe2+ state [69,70]. Further investigation in reducing Fe from the RHA has been initiated by treating RHA with diluted acid.

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FIG. 7.9 A photograph of UV–Vis–NIR spectra of glass.

7.4 Conclusion Glass is considered one of stable materials, and a wide variety of elements can be accommodated within it, including various toxic transition metals (TM) and heavy metals. Arsenic is one of the raw materials required as a refining agent for removing bubbles from the melt. Cr present in TSW can be added to develop a green color in glass. Fe, present in ACS, can be utilized for a brown/yellow color in glass depending on glass composition. This chapter reports incorporation of ACS, TSW, waste glasses, and RHA into a glass matrix to develop various glass products. TSW is added to a glass matrix to produce filter glass, particularly green filter glass. Similarly, ACS is incorporated into a glass matrix and brown color glass is obtained. The potential use of this glass can be in window panels, significantly reducing the electricity load of the building. A feasibility study in CSIR-CGCRI shows more than 90% of glass from glass waste (windshield, tube light waste glass) can be reutilized as cullet in glassmaking as well as foam glass preparation. In the future, composition will be optimized to minimize the leaching of hazardous elements (As, Cr, Fe, etc.) under submerged water at elevated temperature. Therefore, the present chapter summarizes the utilization of toxic elements as ingredients of color in glass and may show the direction of future waste handling and management. The glass that cannot be reutilized (due to the wide variation of composition) would be used for producing glass foam. Foam glass has potential application in lightweight construction material (as an alternate to clay bricks) and can also be used in insulation purposes due to its high porosity (75%–85%).

References

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Acknowledgment We acknowledge Director of CSIR-CGCRI for his kind support to pursue this work. This work is funded by Science & Engineering Research Board (SERB), India [File no. CRG/ 2020/002771 Dated: 17-Dec-2020].

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[58] A.K. Mandal, S. Sen, S. Mandal, C. Guha, R. Sen, Energy efficient melting of glass for nuclear waste immobilization using microwave radiation, Int. J. Green Energy 12 (12) (2015) 1280–1287. [59] A. Roy, et al., J. Environ. Manag. 33 (2019) 141–150. [60] E. Sobiecka, K. Cedzynska, B. Smolinska, Vitrification as an alternative method of medical waste stabilization, Fresenius Environ. Bull. 19 (2010) 3045. [61] A.A. Francis, R.D. Rawlings, R. Sweeney, A.R. Boccaccini, Crystallization kinetics of glass particlesprepared from a mixture of coal ash and soda-lime culletglass, J. NonCryst. Solids 333 (2004) 187. [62] A. Gauthier, P. Le Coustumer, J.H. Thomassin, Thermostability of ultimate glassy wastes, Ann. Chim. Sci. Mater. 26 (2001) 87. [63] H.G. Diaz, M.E. Zayas, F.J. Espinoza, F.J. Valle-Fuentes, Producing optical glass with geothermal waste, Am. Ceram. Soc. Bull. 78 (3) (2000) 57–59. [64] T. Basegio, A.P.B. Leao, A.M. Bernardes, C.P. Bergmann, Vitrification: an alternative to minimize environmental impact caused by leather industry wastes, J. Hazard. Mater. 165 (2009) 604. [65] R.R. Petersen, J. K€ onig, Y. Yue, The viscosity window of the silicate glass foam production, J. Non-Cryst. Solids 456 (2017) 49–54. [66] Kazmina, et al., IOP Conf. Ser.: Earth Environ. Sci. 43 (2016), 012067. [67] L. Ramrakhiani, S. Ghosha, A.K. Mandal, S. Majumdar, Utilization of multi-metal laden spent biosorbent for removal of glyphosate herbicide from aqueous solution and its mechanism elucidation, Chem. Eng. J. 361 (2019) 1063–1077. [68] D. Mukherjee, et al., Arsenic (V) remediation using adsorption-induced ultrafiltration process and management of toxic sludge in glass formation, in: S. Ghosh (Ed.), Waste Valorisation and Recycling, Springer, Singapore, 2019. [69] A.K. Mandal, R. Sen, Preservation of higher Fe[II] content in borosilicate glass by microwave irradiation in air, Mater. Res. Bull. 108 (2018) 156–162, https://doi.org/10.1016/ j.materresbull.2018.08.034. [70] A.K. Mandal, B. Mandal, I. Kavya, T.G. Ajithkumar, A. Halder, P.K. Sinha, R. Sen, Preparation of colourless phosphate glass by stabilising higher Fe[II] in microwave heating, Sci. Rep. (2018) 8:6195, https://doi.org/10.1038/s41598-018-24287-1.

C H A P T E R

8 Agricultural waste: Sustainable valuable products Pranjal Kalitaa, Sanjay Basumataryb, Biswajit Nathb,c, and Manasi Buzar Baruahd a

Department of Chemistry, Central Institute of Technology Kokrajhar (Deemed to be University, Ministry of Education, Govt. of India), Kokrajhar, Assam, India, bDepartment of Chemistry, Bodoland University, Kokrajhar, Assam, India, cDepartment of Chemistry, Science College, Kokrajhar, Assam, India, dDepartment of Physics, Central Institute of Technology Kokrajhar (Deemed to be University, Ministry of Education, Govt. of India), Kokrajhar, Assam, India

8.1 Introduction With the advancement of human civilization and rapid industrialization, the worldwide energy demand, particularly fuel, is increasing. Out of the total energy sources, 81% is originated from petroleum resources [1]. Due to the rapid depletion of nonrenewable petroleum, the fossil resources probably may exhausted by 2050, resulting in an energy crisis [2]. The bulk chemicals, 95 out of 100 used in manufacturing numerous items for modern society, are extracted from petroleum resources. In the USA, 13% of the total crude oil is used to produce nonfuel chemicals [3]. Natural gas is being used in the preparation of fertilizers [4]. The solvents, reagents and educts used in today’s industries are from oils and hydrocarbons extracted from coal. The world population is dependent on nonrenewable fossil sources for energy and essential chemicals. Alongside, combustion and use of these petroleum products are causing pollution, degrading the environment and bringing climate change. Concerning the environment and the future crisis of feedstock for energy and chemicals, the scientific community is in search

Advanced Materials from Recycled Waste https://doi.org/10.1016/B978-0-323-85604-1.00009-3

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of renewable and sustainable alternatives to fossil resources [5]. The future of mankind will be in jeopardy unless an alternative renewable resource for chemicals and energy is combed out. As a renewable and sustainable alternative to fossil, biomass resources can play a potential role in supplementing energy and chemicals for the future generation by solving the growing questions (i) from where the raw materials will come for the chemicals for industrial usage and (ii) where from the energy will be obtained [6,7]. Accordingly, biomass could play an important role as a sustainable alternate feedstock of energy and chemicals [6,8]. In the last few decades, integrated biorefineries have used various biomass feedstocks to produce biofuels and bio-based chemicals [7]. As a potential alternative to fossils for energy and chemicals, biomass resources are becoming an important area of research as it is an excellent source of carbon, lignocellulose and fatty acids [9]. The use of biomass instead of petroleum in producing chemicals and fuels contributes lesser pollution with no net CO2 output to the environment. It results in biodegradable and sustainable products [10]. Both animal- and plant-based biomasses are available plenty in nature, out of which plant-based biomass originated from plant waste and algae are the most commonly used preferable feedstocks for energy and chemicals [11,12]. The animal wastes emit greenhouse gases, produce odor, potentially contaminate surface and ground-water, and are of environmental concern [13]. Algae are microorganisms with a high productivity rate, high lipid content, biodegradable and a good source of methane-rich biofuel [14]. Due to high lipid and carbohydrate contents and other advantages, algae are considered a sustainable and green feedstock for biofuel and chemicals [15,16]. Algae are the primary producers of glycerolipids, carotenoids, and other valuable chemicals, as well as they, can be a host of recombinant proteins with pharmaceutic and therapeutic importance [17,18]. Along with a source for biofuel, algae are also important as feedstock for many commercial chemicals and products and are thus considered sustainable, renewable and green [16]. With several disadvantages, the mostly high production cost for growing, storage, pre-treatment and transportation bring uncertainty in algae as a sustainable and cost-effective alternative feedstock for biofuel and chemicals [16]. Thus, a sustainable, environmentally friendly feedstock with low production cost is foremost important. Incidentally, plant wastebased biomass has huge potential to overcome this context. The current global scenario shows that the total biomass land production exceeded 1.8 trillion tons, which can be an enormous source of chemicals and energy for the world [3,6]. Plant waste biomasses are composed of starch, cellulose, hemicellulose, lignin, and oil, which are being utilized as feedstock for a biorefinery in biofuel production for energy and platform chemicals for industries as well as various value-added products [4,6,19,20]. Lignocellulosic nonfood source biomass, the second most abundant natural polymer, can also be a source for the same [19]. These inexpensive waste parts of

8.2 Current scenario of agricultural waste

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plants constitute a renewable resource for biorefineries for the preparation of a wide variety of value-added products [4,7,20,21]. The agricultural sector is the major producer of plant base biomass wastes worldwide followed by forest biomass waste [4]. The current scenario estimated to be an amount of 140,000 million tons of biomass wastes from the agricultural sector were generated globally per year which is increasing at an average rate of 5%–10% annually [2,22,23]. Food plants such as rice, maize, wheat, millets, beans and pulses are the major food crops for human and animal consumption worldwide. Accordingly, cash crops such as sugarcane, cotton, jute, oilseeds, tobacco, etc. are cultivated globally for utilization in human need. Other important plantation crops such as tea, coffee, coconut, rubber, etc. are also planted at an industrial scale. Similarly, fruits and vegetables are an important part of the agricultural sector for nutritional food commodities. All these agro-based plants produce huge residues that can be utilized to produce value-added products. A flow chart of value-added products from agrowaste is shown in Fig. 8.1.

8.2 Current scenario of agricultural waste 8.2.1 Food crop agrowastes Over the last 8000 years, cereals such as wheat, maize and rice prevailed as staple food sources for humans and animals [24]. Production of these crops in agricultural sectors to alleviate the food demand generates a considerable amount of straw/husk as biomass wastes after the harvesting. Rice is the key crop of human consumption, with more than 100,000 cultivated varieties worldwide [25]. It is estimated that about 1000 million tons of rice straw are generated globally as waste and management become a serious problem for the farmers [26,27]. According to the Food and Agriculture Organization (FAO) of the United Nation, India recorded 221 million tons of rice crop residue in 2019 [28]. As the largest producer of rice in the world, China contributes 30% of the total rice production of the world [29]. Subsequently, India with 24% rice production in the world, stands second in global perspective [29]. About 529 million tons of wheat straw are available globally, which can be utilized to produce value-added products [30]. As a current scenario, the data of FAO of the United Nation reflects that nearly 133 million tons of wheat straws were generated in India [28]. In terms of a maize cob, a total of 250 million tons is reported to produce as waste worldwide, most of which is discarded to the environment [13]. India contributes nearly 24.6 million tons of maize crop residues which can also be used to produce valuable products [28]. Like rice, wheat and maize; millets and pulses are also considered as principal food for

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8. Agricultural waste: Sustainable valuable products

FIG. 8.1 Value-added products from agrowaste.

humans and animals from which a large amount of waste is being generated worldwide. Straw and husk are generated as wastes from food crop residue, which constitute cellulose, hemicellulose and lignin. They can be utilized in the production of platform chemicals, bioethanol, phenolics, biogas, and pharmaceutical chemicals, as well as other materials for construction and industrial usage. Thus, countries with huge food crop waste residues can be a tenant of industries to produce agrowaste-based valueadded products.

8.2 Current scenario of agricultural waste

159

8.2.2 Cash crop agrowastes Cash crops such as sugarcane, cotton, jute, oilseeds, tobacco, etc. are being cultivated for the generation of revenue in the large amount resulting in the production of a huge amount of wastes, which create a significant waste disposal issue. Sugarcane generates waste of sugarcane bagasse; globally, approximately 279 million tons of sugarcane bagasse waste are produced yearly [31]. In global outlook, Brazil is the largest producer of sugarcane followed by India and possesses huge potential to produce various valued products [32–34]. Cotton is the most demanded and important fiber worldwide. Globally, 50 million tons of cotton stalk waste is reported to be generated with significant disposal issues for the environment [35]. China is reported as the largest producer of cotton globally, generating 40 million tons of cotton stalks as waste yearly [36,37]. The position of India in cotton production is third in the global viewpoint [36]. Similar to that, jute is considered as the second most important fiber followed by cotton and produces jute stick as waste. Globally, 7 million tons of jute stick waste are generated annually after extraction of jute fiber [38]. In the global scenario, the lookout of jute production reflects India as the first largest, followed by Bangladesh [39]. These waste jute sticks are being reported in the production of various value-added products such as activated carbon, etc. [40,41]. Oilseed bearing plants are cultivated worldwide for edible oils and oilseed bearing plants resulting in huge waste as husk and stalk. Mustard, sunflower, rapeseed, jatropha, Karanja, mahua, pongamia, etc. are some of the oilseed bearing plants cultivated worldwide. Stalk, cake, etc. are generated as waste from these oil seed-bearing plantation crops. Research output reveals the utilization of these wastes into value-added products such as animal feed, medicine, fertilizer, organic pesticide, etc. [42,43]. As a cash crop and other oil seed-bearing plants, the cultivation of jatropha is also gaining attention as a feedstock of biodiesel production to mitigate the present and future energy crisis. Literature survey reveals the production of biogas, fertilizer, animal feed, activated charcoal, insecticide, soap, etc., from the waste part of jatropha with successful results [43,44]. All these cultivated cash crops resulted in enormous waste after harvesting, which creates management or disposal issues and utilization of which is emphasized in the production of valueadded products.

8.2.3 Plantation crop agrowaste Tea, coffee, rubber, coconut, etc., cultivated as plantation crops, have great importance in today’s world and occupy a huge region of the agricultural sector worldwide. Tea is native to East Asia and is a major refreshing drink worldwide. Globally 5 million tons of tea wastes were generated

160

8. Agricultural waste: Sustainable valuable products

yearly [45]. Out of which, India generates 0.015 million tons of tea waste annually [46]. Coffee is the most popular beverage, with an estimated 2.25 billion cups dunked per day [47]. The coffee industry globally generates 9.34 million tons of coffee waste yearly [48]. Coconut is cultivated in 92 countries at an area of 11.8 million hectares producing a large amount of husk as waste estimated to be 23 million tons worldwide [49]. All these plantation crop agrowastes have great potential in utilizing feedstock for the preparation of value-added products. Tea waste is being reported in the synthesis of carbon nanostructure [50], bio adsorbent [51,52], phenolic compounds [53], filler for natural rubber [45], etc., with successful results. Waste from coffee is also being reported as a raw material in producing the adsorbent for heavy metals, dyes, briquettes, fuel pellets, biogas, bioethanol, natural phenolic antioxidants, etc. [54,55]. Coconut coir waste is also utilized as raw material for the preparation of nanostructured graphite [56], material for light-weight concrete [57], adsorbent for heavy metal from wastewater [58], etc. Waste rubber seeds are reported to extract seed oil as feedstock to prepare biodiesel [59,60]. Likewise, wastes obtained from plantation crop agrowaste possess the potential to be used as raw material for conversion to a variety of value-added products.

8.2.4 Horticultural crop agrowastes Several horticultural crops are cultivated worldwide for their edible fruits as well as for utilization as a vegetable. Cultivation of fruit crops results in huge waste after harvesting. Brazil is the largest producer of fruit and vegetable in the world [54]. A total of 50 million tons of fruits and vegetables are found to be discarded as waste in India [61]. Out of total 8.2 million tons of fruits and vegetable production in Africa, 4.2 million tons of wastes are generated [61]. The US recorded 45 million tons of waste from food yearly [62]. Taghizadeh-Alisaraei et al. reported that global palm waste generation is about 30 million tons yearly [63]. This reflects the severity of the generation of waste from fruits and vegetables worldwide. These fruits and vegetable wastes can be resources for producing various value-based products such as phenolic antioxidants, bioactive compounds, terpenoids, flavonoids, bioethanol, carotenoids, dietary fiber, animal feed, etc. [64,65]. Thus, a biorefinery concept with the utilization of fruit and vegetable waste as feedstock should be emphasized.

8.3 Agricultural wastes toward biorefinery process 8.3.1 Biodiesel With the declining condition of conventional fossil fuel resources, scientists search for renewable and environment-friendly alternatives of the same. Biodiesel has been gaining attention worldwide in the last few

8.3 Agricultural wastes toward biorefinery process

161

decades as an alternative to fossil fuel. Biodiesel is a mixture of fatty acid alkyl esters obtained via transesterification of triglycerides with lower alcohols. Vegetable oils such as jatropha, Karanja, pongamia, mahua, etc., and waste cooking oil, fat, etc. are potentially used in the preparation of biodiesel. Preparation of biodiesel from the agricultural waste product is also being emphasized or can be a potential feedstock. Waste agricultural products containing triglyceride, saturated or unsaturated fatty acids are used as feedstock for biodiesel production. In this regard, waste coffee oil obtained from spent coffee consisting of wax, triglyceride and fatty acids is reported to be used to produce biodiesel with 97.11% of yield [66]. Waste grape seed oil with 8%–20% of oil content is also used in the production of biodiesel [67]. Singh et al. reported the use of waste cottonseed oil in biodiesel production with 78.9% of yield [68]. Similarly, Leku et al. reported the valorization of waste cottonseed oil for biodiesel synthesis with methanol and ethanol, resulting in a good biodiesel yield of 97% and 98%, respectively [69]. Concerning the food crisis, the emphasis is given to using nonedible feedstock for biodiesel synthesis as a promising alternative to fossil fuel. In this regard, waste Date pits with good lipid content are stated for oil extraction and subsequent production of biodiesel [70,71]. Waste rubber seed is also being utilized in extraction oil to synthesize biodiesel and reported 92.1% of yield [59,60]. Calabash seed with a good oil content of 39.3% is successfully used in the transesterification with methanol to biodiesel and reported the highest yield of 96% [72]. With 26.9% of oil content, the waste pepper seed oil is also reported as feedstock for biodiesel synthesis and transesterification with methanol gives 94.1% of biodiesel [73]. Basumatary et al. explored in their review the applicability of yellow oleander seed oil as an alternate feedstock for biodiesel production [42]. Georgieva et al. reported the extraction of oil from waste coffee and grape seed to be used in biodiesel production [67]. Similarly, Chiou et al. also extracted salmon oil from salmon processing waste and hydrolysate and reported biodiesel production from waste salmon oil [74]. Thus, a variety of wastes from the agricultural sector containing oils or fats is being utilized and can be considered additional feedstock for biodiesel production.

8.3.2 Bioethanol As a clean, sustainable and environment-friendly fuel, bioethanol is expected to have a promising future in dealing with the current global energy crisis and mitigating environmental worsening [75]. The utilization of food products as bioethanol feedstock generates economic, social, and political controversies; however, the use of agricultural waste products for the same is gaining attention [76]. Agricultural wastes are out of the food chain, cheap and abundant having the potential for bioethanol

162

8. Agricultural waste: Sustainable valuable products

production. Song et al. schematically represent the production of bioethanol from cellulose via three different pathways via (i) enzymatic, (ii) chemo-catalytic, and (iii) direct synthesis in water [77]. A line diagram for bioethanol production from cellulose obtained from agrowaste is portrait in Fig. 8.2. Rice straw and husk lignocellulose biomass is an abundant source of feedstock for bioethanol production. In this regard, Pabo´n et al. reported bioethanol production potential from rice husk and straw by simultaneous hydrolysis and fermentation process and stated 43.9% of yield [76]. On a comparative analysis, Adeyemi et al. also reported a good yield of 61.55% of bioethanol from rice straw pretreated with alkali (2% NaOH) [78]. Similarly, Riungu et al. converted rice straw and husk to bioethanol by first reducing with sulfuric acid followed by fermentation with bakers’ yeast and reported 87% yield of bioethanol [79]. Yoswathana et al. reported a comparative study on different pre-treatment methods in bioethanol production. They stated acid treatment followed by enzyme treatment is suitable for conversion of lignocellulose to bioethanol from rice straw [80]. Wheat straw is also being successfully utilized in the production of bioethanol [81]. Manyuchi et al. design a plant to produce bioethanol from corn waste and reported the production of 99.5% pure bioethanol [82]. Waste potatoes are also reported as good feedstock for bioethanol production. Memon et al. reported sustainable bioethanol production from waste potatoes via enzymatic hydrolysis with 90 mL bioethanol from 800 g of waste potato [83]. Kilpimaa, et al. also reported bioethanol production from waste potatoes [84]. Accordingly, Duruyurek et al. reported potato waste as a possible economical resource for bioethanol production [85]. Sujeeta et al. optimizes the conditions of bioethanol production from waste potato peel and reported 35°C and pH 6.0 is the best condition for the same [86]. Bioethanol production from other agricultural wastes is also gaining attention. In this regard, Tropea et al. studied bioethanol production from pineapple waste and reported 96% of yield via simultaneous saccharification and fermentation of the waste [87]. Valorization of soybean waste (okara) for bioethanol production by enzymatic hydrolysis was explored by Choi et al. and reported 96.2% of yield [88]. Bhatt and Shilpa studied bioethanol production from Groundnut shell waste by pre-treating with acid followed by enzyme and reported 16.11% of yield at 50°C [89]. Danmaliki et al. studied the efficiency of the pre-treatment methods in bioethanol production. They reported acid pre-treatment results in the highest bioethanol followed by alkaline and water pre-treatment [90]. A comprehensive analysis of bioethanol production from agrowaste is represented in Table 8.1. Literature reveals that bioethanol production from agricultural waste feedstock is suitable via pre-treatment of lignocellulose biomass followed by hydrolysis to obtain bioethanol with good yield.

163

8.3 Agricultural wastes toward biorefinery process

OH OH

H

O

O

HO

HO

OH O

OH

Agro-waste (Cellulose)

OH

n Catalyst O2, Methanol

Water Catalyst

OH

HO O

O HO HO

OH

(Glucose)

OH

H3C

O

(Methyl glycolate)

Catalyst Enzyme H2 O

H2O

Catalyst O

H3C O

(Pyruvate)

CH3CH2OH (Ethanol) FIG. 8.2

Bioethanol production from cellulose biomass obtained from agrowaste [77].

164

8. Agricultural waste: Sustainable valuable products

TABLE 8.1 Comprehensive analysis of bioethanol production from various reported agrowastes. Yield (%)

Reference

Simultaneous saccharification and fermentation

11.16

[89]

Autoclaved at 121°C for 20 min

Enzymatic hydrolysis and fermentation

96.2

[88]

Banana peel

Autoclaved with 10% NaOH at 120°C for 6 h

Hydrolysis followed by fermentation

–

[90]

Pineapple

–

Fermentation

96

[87]

Potato peel

No pretreatment needed

Enzymatic hydrolysis and saccharification

2.51

[86]

Potato

Cooking for 30 min

Saccharification and fermentation

–

[84]

Potato

–

Enzymatic hydrolysis

84

[83]

Jute

Autoclaved with liquid ammonia at 121°C for 20 min

Enzymatic saccharification

7.55

[75]

Rice straw and husk

Concentrated H2SO4

Fermentation

87

[79]

Wheat straw

2% NaOH solution

Hydrolysis followed by fermentation

29

[78]

Rice straw

2% NaOH solution

Hydrolysis followed by fermentation

36

[78]

Rice husk

Mild NaOH solution

Simultaneous hydrolysis and fermentation

38.2

[74]

Agrowastes

Pretreatment method

Production method

Groundnut shell

0.25 N HCl and 0.25 N NaOH

Soybean

8.3.3 Biogas Production of biogas from agricultural waste is in focus due to the massive availability of agrowaste and the high potential of biogas generation with low-cost feedstock and manure as useful by-products. Biogas is produced by anaerobic digestion or fermentation of biomass [91]. Anaerobic digestion is a natural process done by micro-organism in an environment free of oxygen constitutes four stages, viz., hydrolysis, acidogenesis,

8.3 Agricultural wastes toward biorefinery process

165

acetogenesis, and methanogenesis, where hydrolysis and methanogenesis are the limiting step of anaerobic digestion [92,93]. A schematic representation of biogas production via an anaerobic digestion pathway is shown in Fig. 8.3. Biogas is primarily composed of methane (60%–70%) and carbon dioxide (30%–40%) [94]. The kinetics of biogas production via fungal degradation of sugarcane bark, pulp, and rice husk under anaerobic conditions is studied, and 15.2% and 12.5% of yields were reported [91,94]. Similarly, Azouma et al. reported pineapple waste as feedstock for biogas production under anaerobic digestion and stated 41.0%–70.5% of methane content in the produced biogas [95]. Abdelsalam et al. studied biogas production from potato peels, lettuce and peas peel waste by codigesting with cow manure and found 45.4% of methane in the produced biogas [96]. The efficiency of biogas production from rice husk codigesting with cow dung and food waste was studied, and their suitable mixing utility was reported [97,98]. Wheat straw is also a potential feedstock for biogas production [99,100]. Under anaerobic conditions, the digestion of fruits and vegetable wastes was studied for biogas production with a successful outcome [101,102]. The utilization of agrowaste for biogas production can be an emerging issue of research in terms of renewable and sustainable energy for the future.

FIG. 8.3

Reaction scheme for biogas production from agrowastes [93].

166

8. Agricultural waste: Sustainable valuable products

8.4 Agricultural waste toward platform chemicals The synthesis of platform chemicals as a source for the preparation of industrial chemicals is an important need to make the availability of chemicals for industries. In this regard, the preparation of platform chemicals from biomass, especially from agricultural waste, is attracting researchers. A range of platform chemicals is synthesized from biobased sources instead of petroleum-based sources [103–105]. A list of platform chemicals synthesized from some agrowaste is shown in Table 8.2. A flow chart representing the conversion of agrowaste to a range of platform chemicals is shown in Fig. 8.4. 5-Hydroxymethyl furfural (HMF) an efficient platform chemical is reported to be produced from D-fructose obtained from biomass [106,115]. Along with HMF, its derivatives such as levulinic acid, 2,5-bis (hydoxymethyl) furan, 2,5-diformyl furan, and 2,5-furan dicarboxylic acid are also promising platform chemicals obtained from fructose via catalytic conversion (Fig. 8.5) [112]. Diacids such as succinic, fumaric, malic, 2,5-furan dicarboxylic acid, aspartic acid, glucaric, glutamic acids and itaconic acid, other acids 3-hydroxy propionic acid and levulinic acid as well as glycerol, sorbitol, 3-hydroxybutyrolactone, and xylitol or arabinitol, etc. are some of the

TABLE 8.2 Platform chemicals prepared from agrowastes. Waste raw material

Platform chemicals

Reference

Jute

Ethanol

[75]

Sugarcane bagasse

5-Hydroxymethylfurfural

[104]

Wheat straw

Levulinic acid

[104]

Fructose waste

5-Hydroxymethylfurfural

[106]

Sugar waste

1,4-diacids succinic, fumaric and malic, 2,5-furan dicarboxylic acid, aspartic acid, 3-hydroxypropionic acid, glucaric and glutamic acids, itaconic acid, levulinic acid, glycerol, sorbitol, 3-hydroxybutyrolactone, and xylitol or arabinitol

[107]

Corn cob

Xylose, furfural

[108]

Corn cob

Furfural

[109]

Cellulose from jute, rice, corn, wheat, etc.

Levulinic acid, gluconic acid, sorbitol, ethylene glycol, 5-hydroxymethylfurfural, lactic acid

[110]

Starch

Glucaric acid, 5-hydroxymethyl furfural, 2,5-diformylfuran, 2,5-furandicarboxylic acid, 2,5-dimethylfuran, levulinic acid and sorbitol

[111]

FIG. 8.4 Conversion of agrowaste to platform and pharmaceutical chemicals [112–114].

168

8. Agricultural waste: Sustainable valuable products CH2OH O O

OH

HO

Fructose

OH

CH2OH

OH

HO

O

HO

O

OH

Succinic acid

O

O2

O

Maleic acid

O2

-H2O

OH OH

O O

OH

H2O

O

H2

OH

O

Levulinic acid

Ca rea nnizz ctio aro n 5-Hydroxymethylfurfural OH-

O

O

O2 O

5-Hydroxymethylfuran carboxylic acid OH

OH O

O2

O

ti eac on

OH

OH

5-Ethoxymethylfurfural

OH-

ro r

OEt O

2,5-Bis(hydroxymethyl)-furan

za niz

O

Me2CO

H Et O 2,5-Diformylfuran

Can

Cross aldol condensation

O

O

2,5-Dimethylfuran

O O

O

O

O

O

O

HO

OH

2,5-Furandicarboxylic acid OH

OH

Hy

o dr

a ne ge

n tio

Cr os s

OH

O

OH

al do lc o H nde 5-Formyl-2-furancarboxylic acid M F nsa tio n

OH

O

OH

O

O

OH

OH

Dehydration/ Hydrogeneation

Dehydration/ Hydrogeneation C12-C15 Alkane (Fuel)

FIG. 8.5 Derivative of 5-hydroxy methyl furfural [112,116–120].

platform chemicals produced from bioprocessing of sugar-containing waste biomasses [107]. Alam et al. reported synthesizing a variety of platform chemicals from biomass by biocatalytic transformation [121]. Similarly, Chang et al. successfully utilized wheat straw to produce levulinic acid, a good platform chemical with a 19.86% yield [122]. Singh et al. stated the synthesis of

8.5 Agricultural waste toward pharmaceutical chemicals

169

very useful platform chemical ethanol by enzymatic saccharification and fermentation of jute waste [75]. Li et al. prepared xylose and furfural by hydrothermal treatment of corncob via solid acid catalyst and reported a yield of 6.18 g/100 g and 6.80 g/100g of corncob, respectively [108]. Zhang et al. also reported the preparation of furfural from corncob by solid acid hydrothermal treatment [109]. Various methods for producing platform chemicals such as ethylene glycol, gluconic acid, lactic acid, levulinic acid, sorbitol, 5-hydroxymethylfurfural from gluconic biomass were reported [110]. Thus, agro wastes can be a good source for several platform chemicals for the synthesis of various chemicals for industrial purposes.

8.5 Agricultural waste toward pharmaceutical chemicals The utilization of biomass, particularly agricultural waste, for the synthesis of pharmaceutical chemicals is also an emerging area of research. In this regard, carbohydrates, cellulose, etc., are being utilized to synthesize pharmaceuticals or precursors of pharmaceutical compounds. Sugar alcohols such as xylitol and sorbitol are prepared by catalytic hydrogenation of sugar, which are also used as a sweetener and an intermediate for vitamin C synthesis [123]. Levulinic acid, a precursor of pharmaceuticals, is prepared from HMF, which is organized by acid treatment of glucose obtained from hydrolysis of cellulose [123,124]. Lignocellulosic biomass obtained from agricultural waste containing cellulose, hemicellulose and lignin can be a feedstock for the preparation of various pharmaceutical chemicals. Ng et al. explored the preparation pathway of vitamin A, vitamin B12, penicillin, paracetamol, lactic acid, etc. from glucose and sugar obtained from cellulose, hemicellulose, and various other pharmaceuticals from the lignin [113]. Fig. 8.4 displays the conversion of agrowaste to some of the pharmaceutical chemicals and precursors. Tey et al. explored the pathway to synthesize pharmaceutical products from palm-based biomass and designed mathematical modeling to optimize a path for biorefinery reaction [114]. Gallezot, in his critical review, specified the synthesis of pharmaceutical precursors such as xylose, furfural, levulinic acid, sorbitol, etc. (Fig. 8.4) from cellulose and hemicellulose biomasses obtained from agricultural wastes [112]. Kamel et al. also reported the various preparation methods of valuable pharmaceutical ingredients such as nanofibrillated cellulose and cellulose nanocrystals derived from cellulose obtained from agricultural wastes such as cotton and wood waste [125]. A summary of various pharmaceutical chemicals derived from agrowaste is listed in Table 8.3. Agrowaste can be in the queue of medicinal research regarding alternate feedstocks for pharmaceutical chemicals.

170

8. Agricultural waste: Sustainable valuable products

TABLE 8.3 Pharmaceutical chemicals prepared from some reported agrowastes. Waste raw material

Pharmaceutical chemicals prepared

Reference

Tobacco

Levulinic acid

[124]

Wheat straw

Levulinic acid

[124]

Wood

Hydroxy methyl furfural

[123]

Wood

Nanocellulose

[125]

Palm

Penicillin, paracetamol, vitamin a, vitamin B12, glucose oxidase, lactic acid cream, sweetener

[113]

Palm

Penicillin, vitamin A, paracetamol, vitamin B12

[114]

8.6 Other value-added products As a potential feedstock for value-added products, along with the above-mentioned products, agrowastes are also used to prepare various other materials for construction, machinery, biomedical uses, biosorbent, etc. (Fig. 8.6). Zhou et al. reported the utilization of cotton stalk in the preparation of fiberboard with good thermal conductivity [126]. Similarly, banana branches are also used to prepare fiberboard [125,127]. Brick for construction, bagasse ash as cementing material, etc. are also reported to be prepared from agrowaste materials [128]. In this regard, Prusty et al. reviewed the use of agrowastes such as sugarcane bagasse, groundnut shell, rice husk, tobacco waste, etc. as a fine aggregate for the preparation of concrete and reported their efficiency in the applications [129]. As a remover of toxic metals from wastewater, Musa paradisiaca peel was reported as a biosorbent and effectively removed Pb2+ and Cd2+ from contaminated water [130]. Preparation of food supplements from agrowastes such as potato waste, corn pod, sugarcane hydrolysate, olive oil waste, etc., was reviewed and explored for uses in food industries [131]. Agrowaste of orange, carrot, onion and apple were investigated for bioremediation of cyanide contaminated wastewater with a successful result and stated higher efficiency of orange followed by carrot, onion and apple in the degradation of cyanide [132]. Adeyemi et al. reported the production of automotive brake pads as friction lining material from ternary agrowaste filler as an alternative to asbestos [133]. Nath et al. reported the preparation of biocatalysts from waste Brassica nigra and Sesamum indicum and reported their applications in the transesterification of vegetable oil to biodiesel [134,135]. Basumatary et al. also reported the low-cost production of catalyst from the waste Kesseru plant for efficient converting jatropha oil to biodiesel via transesterification with methanol [136].

8.7 Conclusions

FIG. 8.6

171

Other value-added products from agrowaste.

In addition to these, Zubairu and Gana successfully produce and characterized the briquette charcoal from corn cobs as a fuel source with the calorific value of 32.4 MJ/kg [137]. Kaur et al. reported rice straw as raw material for making paper [138]. Thus agrowastes can be potentially used to prepare a variety of materials of human need.

8.7 Conclusions The world population generates a massive amount of biomass waste, and agricultural-based biomass dominates. The agricultural sector is the major contributor to plant-based waste. Agrowastes with oil or fat contents are emerging as supportive feedstocks for biodiesel production. Due to their variety of chemical contents, these agrowastes have great potential for conversion to value-added products. Similarly, cellulosic agrowaste contributes to bioethanol production as second-generation biofuel and the production of biogas as fuel for cooking and industries. Growing demand is focused on agrowastes as a resource for the production of platform chemicals to prepare chemicals with industrial importance. Several pharmaceutical chemicals are also being obtained from agro wastes. Competing with other value-added products, extraction of materials for construction, automotive, and medicinal and purification purposes is also of great importance. Thus, the waste obtained from the agricultural sector with phenomenal possibility could be successfully utilized to produce various value-added products for human and societal needs.

172

8. Agricultural waste: Sustainable valuable products

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C H A P T E R

9 Use of industrial waste for value-added products Dilip D. Sarode Department of General Engineering, Institute of Chemical Technology, Mumbai, India

9.1 Introduction With the increasing population and urbanization, there is an increased demand for shelter. This demand has subsequently led to an increase in demand for construction materials. This excess demand compared to the supply is causing scarcity of cement and other construction materials, leading to an increase in construction costs and depletion of natural resources. Socioeconomic, technocompetent, ecofriendly solutions to this industrial waste is now gaining much more impetus at a global level for a sustainable, cleaner, and greener environment. Disposal of large quantities of industrial waste on land is posing a great threat to the environment, leading to cause some serious geoenvironmental issues of pollution of land, water, and air. Annual generation of industrial solid wastes such as coal combustion residues (fly ash, boiler slag, bottom ash, etc.), red mud (bauxite residue), waste from aluminum, iron, copper, and zinc primary extraction processes, industries of fertilizers and plastics already accumulating wastes in stockpiling yards are a major source of geoenvironmental pollution. According to an estimate, by the year 2025, the annual generation of solid waste is likely to reach 19 billion tons [1]. With more and more innovative ways of using these materials, it is possible to reduce the consumption of conventional building materials and to substitute them partly or fully for various applications. Day by day, there is depletion of natural resources used for the construction of houses, creation of infrastructure, and raw materials used in industries. Recently, for certification as green building, all factors such

Advanced Materials from Recycled Waste https://doi.org/10.1016/B978-0-323-85604-1.00004-4

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as source of all the materials used for construction, its availability in the local area, and use of recyclable materials have gained importance. Government has also taken initiatives such as fly ash mission for increasing the use of fly ash for various applications. Nonavailability of good quality raw materials started affecting the quality of products, for example, the quality of bricks in urban areas. A lot of construction and demolition debris are occupying valuable land in urban areas. Moreover, the increase in industrial production increased waste generation many-fold. This not only created the problem of disposal without any environmental hazard but also started polluting water resources and air. This is leading to lot of health issues and has started affecting the climate. In this chapter, we will examine the various wastes generated and its utilization for value-added products. As a lot of work is done and literature is available on fly ash from thermal power plants and ground granulated blast furnace slag from the steel industry, more detailed information will be given for all other industrial waste. Presently, fly ash is available at almost 40%–50% less than the cost of ordinary Portland cement, and GGBFS is about 50%–60% of the cost of ordinary Portland cement. Increased use of these materials in cement composites will not only reduce the overall cost of the material but also help the end user in Leadership in Energy and Environmental Design (LEED) certification.

9.2 Different industrial waste and their uses Cement is the most abundantly used material per capita after water. This use of cement is highly energy intensive and produces lot of greenhouse gases. Hence, for sustainable development, an attempt should be made to reduce consumption or reduce the natural raw materials used in its production. Use of the following industrial wastes in cement and its composites will be of immense help in achieving this objective.

9.2.1 Fly ash and ground granulated blast furnace slag (GGBFS) Ever-increasing needs of housing and infrastructural development are leading to very high consumption of cement and aggregates. Cement and cement products are the largest consumable materials in the world, next to water. This is posing a great threat to environmental protection and sustainability issues. Production of cement is an energy-intensive process, and a large amount of carbon dioxide is liberated in this process. Cement production process releases 0.8–1 ton of carbon dioxide per ton production of cement. Thus, there is a need to explore the material that would replace cement in mortar and concrete.

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Fly ash and GGBFS are waste industrial by-products from thermal power plants and steel industries, respectively. Globally as well as in India, more than 50% of the power demand is satisfied by thermal power plants. During the process of power generation, a lot of coal is used as fuel. Depending on the type of coal used and the efficiency of the plant, the quality, type, and quantity of fly ash generated varies in the thermal power plants. The fly ash generation during 2018–19 was 226.13 million tons due to the combustion of 678.68 million tons of coal/lignite [2]. A lot of GGBFS is generated in the steel industries while manufacturing steel from iron ore. Fly ash and GGBFS have pozzolanic characteristics, as they are used as a supplementary cementitious material in cement composites and manufacturing of blended cements. Fly ash and GGBFS reacts with Ca(OH)2, which is produced during the hydration of cement so as to produce secondary hydrated products such as calcium silicate hydrate (C-S-H) gel leading to improvement in pore refinement. Due to refinement, many properties of cement composites are improved when they are fresh as well as in a hardened state. Hence fly ash and GGBFS are used for manufacturing of value-added products. The selection of material is based on availability, basic cost, transportation cost, and quantity of material to be manufactured. The applications of fly ash and GGBFS for value-added products are as follows: 9.2.1.1 Blended cements Cement is the most abundantly used material per capita after the use of water. Moreover, manufacturing of cement uses many natural resources such as limestone and clay material; also it is an energy-intensive process and generates a lot of CO2 emission during the process. Hence, much research is done to use industrial waste materials such as fly ash and GGBS for manufacturing of blended cements or during the preparation of cement composites. To produce the same cement, clinkers are intergrinded with fly ash or GGBS to produce blended cement. Increasing use of these waste products in thermal power plants and steel industries not only reduce the requirement of raw materials for cement manufacturing but also reduce the pollution caused by liberation of carbon dioxide during the manufacturing of cement. This also mitigates the problem of disposal of fly ash and GGBS as well as pollution caused by them. An advantage of using blended cements in constructions is that it helps to improve the properties of fresh and hardened cement composites. Fly ash and GGBS are known as secondary cementitious materials as they have pozzolanic characteristics. Due to the spherical surface of fly ash, there is improvement in workability of the cement composite, particularly concrete. Incorporation of fly ash or GGBS or use of blended cement reduces the water demand and avoids segregation and bleeding in

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concrete when it is fresh. Reaction of this supplementary cementitious material with Ca(OH)2 helps to reduce the ill effect of Ca(OH)2 on cement composites. This improves the durability of concrete by improving resistance to water/air permeability, chloride penetration, and chemical attack. When the air, water, and chloride ion permeability is reduced, obviously the corrosion of embedded reinforcement is also reduced. Another advantage of using fly ash, GGBS, or blended cements is reduction in the heat of hydration. Hydration of cement is an exothermic reaction generating a lot of heat during the process of setting and hardening. This limits the use of large pour of concrete made with ordinary Portland cement at a time. If large amount of concrete is used at a time, then the energy generated is dissipated leading to creation of microcracks in the body of concrete. Hence improved resistance to thermal cracking is observed. For massive constructions such as a concrete gravity dam or large-size foundations, blended cements or concrete with supplementary cementitious materials are used [3]. Fly ash and GGBFS are used to manufacture fly ash-based Portland cement and production of Portland Blast Furnace Slag cement (PBFSC). Use of these cements in concrete is well accepted and largely used. This not only helps to improve the properties of concrete but also addresses the issue of the disposal of industrial waste material. In addition to blended cement, fly ash and GGBFS are used for production of following value-added products. Though most of these products are manufactured with fly ash, some of the manufacturers use GGBFS as well due to availability in the vicinity and quality. 9.2.1.2 Use of Fly ash/GGBFS in concrete Almost 75% of concrete used in urban areas is now made with fly ash or GGBFS as an ingredient. Water demand and air content of concrete is greatly affected by the fineness and carbon content properties of high lime fly ash/GGBFS. Early age compressive strength of concrete with supplementary cementitious materials is low; however, the desired strength is obtained at 56 days. Concrete containing 25%–35% high lime fly ash achieved best strength properties, whereas higher amount of GGBFS is used to manufacture concrete. Sometimes high-volume fly ash concrete is also used in roller compacted concrete in various applications such in construction of roads, dams, and container yards. The amount of fly ash and GGBFS to be incorporated depends on the mix design of the concrete. These supplementary materials react with the Ca(OH)2, which is produced during the hydration of cement so as to produce secondary hydrated products leading to improvement in pore refinement. Since the cement has to hydrate first and produce Ca(OH)2 which then reacts with fly ash and GGBFS, the rate of development of strength is slow. Due to this the ill effect of Ca(OH)2 on cement composites are reduced.

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This improves the quality of concrete and makes the concrete more durable due to decrease in water, air, and chloride permeability of concrete. This makes concrete with better durability properties. Nowadays, concrete manufacturers started manufacturing concrete with tertiary blended concrete. In these types of concrete, fly ash as well as GGBFS both are used. 9.2.1.3 Ready-mix plaster Ready-mix plaster is prepared by using crushed rock, fly ash/GGBFS, cement, and chemical admixtures due to limitations in availability of good quality sand. To maintain consistency in quality of cement mortar used for plaster, ready-mix plaster material is gaining importance. The advantages of this material are consistent quality, uniform particle size distribution, good bonding with base, and water and damp proofness. Due to incorporation of supplementary cementitious material, there is less heat of hydration. Since plaster is a thin coat of cement mortar on the surface of bricks or blocks, there is reduction in the tendency of plastic shrinkage and thermal cracking. Due to shortage of supply and difficulty in availability of 33 and 43 grade cements, ready-mix plaster material is used on many projects. 9.2.1.4 Masonry bricks and blocks Due to nonavailability of good quality of clay, which is one of the most important ingredients in manufacturing of bricks, the quality of bricks in most of urban areas is affected. Moreover, there is pollution in the vicinity of the brick kilns. Hence nowadays either cement concrete blocks or fly ash bricks can be a good alternative to conventional clay burnt bricks. Moreover, in the vicinity of power plants, the government made it mandatory to use brick or blocks manufactured using fly ash. Fly ash/GGBFS-based blocks for construction of load-bearing structures and walls in framed structures have good strength with less weight (leading to reduction in dead load). This helps to save foundation costs in steel and concrete framed structures. These blocks are easy to handle, and less dimensional variation in wall thickness is observed. Due to uniform thickness of wall, less mortar is required for joints and plaster. 9.2.1.5 Wall panels A lot of fly ash and GGBFS are used in manufacturing of wall panels of varying thicknesses. Wall panels of 50 mm and 75 mm thickness with a core of fly ash-based material is manufactured by many companies. These wall panels are used for many mass housing projects, such as partition walls in many housing and industrial buildings. In many urban cities, temporary housing of redevelopment projects or in slum rehabilitation work projects, these wall panels are used for constructing houses. By use of these panels, the speed of construction can be increased many-fold.

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9.2.1.6 Microconcrete and repair mortar Microconcrete and repair mortars are nowadays available in prepacked forms of various quantities. This material contains processed fly ash or GGBFS as one of the ingredients. Use of such materials is justified as the amount of material required is less in some of the small repair jobs. Moreover, there is consistency in quality of material used in repair jobs. Due to less shrinkage, less wastage, and nontoxic nature, these materials can be used for all types of repairs including repairs of water tanks and food storage structures. Minor repair work can be done without affecting the functioning of the premises. 9.2.1.7 Grout material Many times, to repair leakages in dams, filling the ducts of cables in prestressed concrete members, or in repairs of underground constructions/honeycomb areas, a lot of grout materials is used. Grout material is manufactured using fly ash/GGBFS and cement. Due to the fineness of these materials along with the chemical admixtures, the grout material shows very good flow properties. Due to the spherical shape of the fly ash, intergranular friction is reduced, thereby giving good workability with less chemical admixture. Such ready-mix grout mixes are widely used for pressure grouting in repairs of honeycomb in concrete in various structures. 9.2.1.8 Masonry mortar There is tremendous shortage of good quality river sand either due to restrictions from the government or gap in demand and supply. To maintain uniformity in cement mortar used for brick or blockwork, masonry cement mortar is becoming popular in many construction projects. Masonry mortar is made up of crushed rock, cement, fly ash/GGBFS, and chemical admixtures. This is mainly because of high bond strength and less wastage. It has been observed that there is not only saving in time, wastage, and labor, but also enhanced speed is observed, particularly when masonry is done with the blocks. 9.2.1.9 Tile base material It has been observed that, to reduce cost and improve performance of blended cement of fly ash or GGBFS or OPC, either this blended cement or cement with these supplementary cementitious materials can be used in manufacturing of mosaic tiles base. In mosaic tiles, usually the base is 60%–75% made with gray cement. This helps not only to reduce the cost but also improve the performance of the tiles manufactured.

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9.2.1.10 Tile adhesive material The adhesive material is manufactured with cement, fly ash/GGBFS, and polymer-based additive. This makes a ready-made adhesive material for fixing ceramic tiles, particularly on walls. This helps to reduce the thickness of cementing material and to have good bond with the base material. This also helps in reducing wastage and improves the speed of tile fixing, making this operation economical.

9.2.1.11 Other applications In addition to the prior major applications, if the quality of fly ash/ GGBFS used is not suitable to manufacture these products, they can be used as soil conditioner in farms, landfills in embankments, and low-lying areas. Some researchers have also tried fly ash as an additive for altering the resistivity properties of polymer composites. However a lot of fly ash is still available in holding ponds of thermal power plants. In addition to fly ash and GGBFS, people have also started using slag from other industries such as ferrochrome industries and foundry sand [4].

9.2.2 Phosphogypsum—A fertilizer industry waste Phosphogypsum is a waste product generated by many fertilizer plants during the manufacturing of phosphate-based fertilizers. During the process of manufacturing fertilizer, phosphogypsum is obtained in the manufacture of phosphoric acid by the wet process, by dousing rock phosphate with sulfuric acid, and subsequent filtration and washing. This is one of the major processes during the manufacture of fertilizer from phosphate-based rocks. Depending on the source of rock phosphate, about 4.5–5.0 tons (dry basis) of by-product phosphogypsum is generated per ton of phosphoric acid (as P2O5) recovered. The global generation of phosphogypsum is more than 280 million tons per annum. In India, over 6 million tons of phosphogypsum is produced per annum. Therefore, to address these issues, development of suitable alternatives for replacing traditional construction materials is a significant topic of research and has attracted a lot of attention in recent times. The handling of phosphogypsum through trucks or railways involves loading, unloading, and temporary storage at yards/depots and is likely to cause environmental impacts, especially during a rainy season. The following innovative value-added products or applications are developed using phosphogypsum.

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9.2.2.1 Phosphogypsum-based plaster The formulations of gypsum plaster were prepared with specific proportion of gypsum, water, retardant, plasticizer, and hydrophobicizers and at different water-to-solid ratios (0.55 and 0.65). A higher water-tosolid ratio will impart higher flowability. These specimens, in the form of cubes, were tested for their compressive strength using a compression testing machine after different curing days. Knife set time test and flow diameter measurements, water uptake study (Cobb test, EN 520), surface hydrophobicity (EN 520) water drop test, water absorbance study (ASTM C642), and shrinkage study (ASTM C490) were performed. The composition of disclosed invention consumes large quantities of phosphogypsum and helps in abating pollution and disposal problems associated with phosphogypsum. The author successfully developed this application by using the phosphogypsum from Rashtriya Chemicals and Fertilizer (RCF), Mumbai, and successfully patented the same. Joint Patent was sanctioned on April 28, 2020 [5].

9.2.2.2 Phosphogypsum-based wall putty A large amount of phosphogypsum is used to manufacture wall putty used for finishing the wall before painting. Wall preparation is one of the most important steps in the process of painting. The better you prepare the wall with wall putty, an increase in the coverage of area per unit volume of the paint is achieved. Besides this, the appearance of the painted surface is improved due to removal of unevenness by application of wall putty.

9.2.2.3 Phosphogypsum wall panels In many developed countries, most of the internal walls are made with gypsum. In India, RCF and a few private players manufactured wall panels using phosphogypsum along with glass fibers as a major ingredient. These wall panels are used for constructing houses and partition walls. As these wall panels are hollow, the dead weight of the panel is less, and we can make innovative use of these panels. Such panels will be of immense help, particularly for emergency setting up of shelters during natural calamities such as earthquake, floods, etc. In most developed countries, walls are made with mined gypsum, hence we use the same technology for manufacturing wall panels using phosphogypsum, but we need to take care of various impurities in it during the industrial process. These impurities may affect the setting and hardening of the wall panel.

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9.2.2.4 Plaster boards, false ceiling Many architects suggest the use of boards manufactured using phosphogypsum and fibers for their use either in providing false ceilings or to have good finish to the walls. As phosphogypsum with cement and other chemical additives-based composition have high resistance capacity for water or humidity and will set very fast, many intricate designs are prepared by use of suitable molds for casting them. The concentration of the retarder and plasticizer should be such that it will give required workability, flowability, and time to place in position. Much phosphogypsum is used in making the boards for providing false ceiling in theaters, drama halls, and residential and commercial buildings. Composition of phosphogypsum can be used in production/manufacture of plaster, plaster boards, gypsum fiber boards, and gypsum blocks having high water resistance capacity, so as to protect the construction and internal walls from rainwater. 9.2.2.5 Making statues and models Phosphogypsum is widely used in making statues for various festivals, flowerpots, and decorative items. Besides this, phosphogypsum is used as a soil conditioner by many farmers for filling of low-lying areas by blending it with other suitable materials with proper care.

9.2.3 Red mud—Waste from aluminum industry Aluminum metal is an important strategic material with global annual production of about 50 million tons. A majority of the aluminum is derived from alumina [6]. Over 95% of alumina manufactured globally is derived from bauxite ore by Bayer’s process. This process results in the production of a large amount of dust-like bauxite residues, alkaline in nature, which is known as red mud. It is one of the largest industrial by-products in modern society estimated at about 3000 million tons at the end of 2010. The global inventory of this waste is growing by approximately by 120 million tons per annum. Each ton of alumina generates about 1–1.6 tons of red mud. An inventory of about 3 billion tons of red mud is awaiting in stockpiling yards. Stockpiling needs large land areas and are liable to be contaminated by air, water, and land pollution. The disposal cost of red mud is about 1%–2% of alumina’s price, which is very high. Thus, this high alkaline red mud generated during the production of alumina poses a serious threat to the environment. Sources of bauxite and the mineralogical process parameters determines the chemical and mineralogical composition of bauxite residue. Major constituents of red mud are Al2O3, Fe2O3, SiO2, TiO2, and some amount of CaO.

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More than 9 million tons per annum (MPTA) of red mud is generated in India, and a huge amount of red mud is awaiting bulk utilization in abandoned storage areas. There is an urgent need to explore methods of utilization of this red mud for some constructive purpose. It is well established that red mud can be used in various cement and cement-based composites for production of building blocks, tiles, paver blocks, bricks, precast components, etc. It is found that red mud concrete components offer better resistance to chloride penetration thus helping to improve durability of end products. Applying red mud as an environmental remediation material is a new hot point in terms of utilization. Much research is in progress in this area. Value-added products and application of red mud are discussed in the following sections. 9.2.3.1 Cement production Red mud contains CaO as well as SiO2, hence addition of red mud as a raw ingredient helps to reduce clinkering temperature in the process of manufacture of cement. Red mud, fly ash, lime, and gypsum as raw materials, when introduced along with the basic ingredients of cement manufacturing, not only reduce the energy consumption of cement production but also improves the early strength of cement and resistance to sulfate attack. Iron-rich, special-setting cements with higher strength as compared to ordinary Portland cement have been made by adding red mud and gypsum together up to 50% in India. 9.2.3.2 Cement mortar and concrete with red mud Red mud concrete prepared by Zhang proved to be better than ordinary cement concrete for pavement materials [7]. The compressive and flexural strength of this red mud concrete after 28 days was in the range of 30–40 MPa and 4.5–5.5 MPa, respectively. Zhuhai et al. developed alkali slag red mud cement that has the properties of greater early strength and a very high compressive strength of 125 MPa. Excellent resistance to corrosion was recorded by utilizing 30% of red mud in concrete [8]. Our research group successfully developed the M35 grade concrete using red mud as one of the ingredients. Extensive trials were done to utilize red mud as a replacement to cement and crushed fine aggregate [9,10]. It is observed that replacement of cement with red mud from 5%–15% improves the tensile and flexural strength of mortar. Without reducing the flexural strength of concrete, the RCPT values are reduced from 3166 to 2358. This is indicative of better strength and durability of concrete [11]. This is also an indication of better resistance to chloride penetration [11].

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9.2.3.3 Checkered tiles and paver blocks Our research group successfully developed checker tiles by replacing dolomite powder with red mud in a wearing course. Coloring pigment content was reduced by 50% of the control mix. It is observed that the density of the material developed is higher and the compressive strength was also higher. On similar lines, paver blocks were also tried using red mud as one of the major materials; no additional use of color pigments were required as the color of red mud itself gave the red color to the paver block. The tiles or paver blocks can be developed to carry more load with less thickness. 9.2.3.4 Geopolymers concrete The formation of geopolymers involves the dissolution of silica and alumina species in an alkali. This will then result in initiation of polymerization of a—(-Si-O-Al-O-) n- polymer chain. The presence in bauxite residue of aluminum and silicon species in a highly alkaline material could offer attractive opportunities to the manufacture of construction materials. Many places such as internal roads and pathways were made with geopolymer concrete prepared using either fly ash or red mud in many parts of the country. 9.2.3.5 Brick manufacturing Good quality clay material for manufacturing of bricks is not easily available, particularly in urban areas. As an alternative to traditional raw materials used in brick production, red mud utilization can not only reduce the cost of raw materials but also has great environmental significance. Red mud partly substituted for the ingredients for manufacturing bricks will be of immense help for bulk utilization of red mud. However, precautions should be taken while handling this material due to its alkaline nature. Massive structural bricks were produced by geopolymerization process by using red mud by synthesizing inorganic polymeric materials. It is observed that compacted clay samples containing red mud and cement–red mud additives have a high compressive strength and decreased hydraulic conductivity and swelling percentage as compared to natural clay samples. A lot of work is done in AMPRI, Bhopal, CBRI Roorkee, and NIT Rourkela on this. 9.2.3.6 Ceramic products Ceramics are classified as inorganic and nonmetallic materials that are essential to our daily lifestyle. Ceramic and materials engineers are the people who design the processes in which these products can be made,

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create new types of ceramic products, and find different uses for ceramic products in everyday life. A ceramic is any of the various hard, brittle, heat-resistant, and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. The presence of calcium, silica, and soda in red mud are beneficial in the formation of vitreous glazes. At higher temperatures around 1000°C, the presence of silica and soda in the red mud promotes the formation of sodium silicates, which improves the flowability of the material and increases the final strength of the product. With these application, red musk can be used in various types of ceramic materials such as like tile, bricks, plates, glass, and toilets [12]. 9.2.3.7 Wastewater treatment Red mud presents a promising application in water treatment for removal of toxic heavy metals and metalloid ions; inorganic anions such as nitrate, fluoride, and phosphate; as well as organics including dyes, phenolic compounds, and bacteria. Sewage disposal chambers may be provided with wall linings of red mud concrete [13]. RM is characterized by small particle size, porous skeleton structure, large specific surface area, and good stability in water medium, which provides good adsorption properties and its utilization as a cheap adsorption material in the field of environmental management. Red mud adsorbents can adsorb PHEs in wastewater and remove F , PO43 , organic pollutants (dyes), and radioactive ions (Cs-137, Sr-90, and U) in wastewater. Domestic and foreign scholars consider red mud as the main body of adsorption and treat it to improve its adsorption performance and expand its applicability [13]. 9.2.3.8 As a catalyst A novel application of red mud as coagulant, adsorbent, and catalyst for environmentally benign process is very well established. It is also used as a catalyst in petroleum refinement. The main components of red mud are Fe2O3, Al2O3, SiO2, CaO, Na2O, and TiO2, which account for approximately 85%. Based on the composition of red mud, it can be recycled and used in a variety of fields. For example, it can be used for recovery of metals or can be used as a potential alternative catalyst since it mainly consists of a mixture of oxides of Fe, Al, and Ti, and a smaller amount of Si, Ca, and Na [13]. Some researchers use red mud as a catalyst for the solar degradation of aquatic pollutants and photocatalyst for removing Cr(VI) and malachite green from wastewater. A series of RM/MCM-41 composite materials (RMCM) were prepared by a simple sol–gel method in which the structural advantages of MCM-41 played a vital role in inhibiting e /h + recombination [13,14].

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9.2.3.9 As a filler in plastic For polyvinylchloride (PVC), red mud is not only a filler that has a reinforcing effect, but it is also an efficient and cheap thermal stabilizer, providing the filled PVC products with an excellent antiaging property. Its lifetime is two to three times that of ordinary PVC products. At the same time, the fluidity of red mud is better than other fillers, which makes it a plastic with good processing properties. And the red mud + PVC composite plastics have a fire-retardant property and can be made into red mud plastic [12].

9.2.4 Rice husk ash The by-product from the milling process of paddy rice is rice husk with a huge amount being produced worldwide each year. Silica in an amorphous form is present abundantly in the rice husk. Thermochemical conversion of rice husk, such as by pyrolysis, gasification, and combustion, can be used to generate value-added by-products and thus substantially reduce the pressure on the environment. Use of rice husk ash for various value-added applications are discussed next. 9.2.4.1 Cement composites Rice husk ash is also used as a part substitution in cement composites. However, use of this material on a bulk scale is not yet estimated. However, laboratory research suggests that, due to pozzolanic nature and abundant presence of silica, rice husk can be used in all types of cement composites. 9.2.4.2 Silicon-based materials Hence, rice husk is a natural biomass source for manufacturing siliconbased materials by extraction of silica [15]. It is used for a number of compounds such as manufacturing of silica, silicon tetrachloride, silicon nitride, silicon tetrachloride, zeolite, and pure silicon. Currently, for extraction of silica on an industrial scale, only a small amount of rice husk is used. 9.2.4.3 Adsorbents in vegetable oil refining and removal of heavy metals Phenol is a common toxic organic pollutant that is widely present in refineries, petrochemicals, pharmaceuticals, polymeric resins, coal tar distillation, and other industrial processes. Generally, the pretreatment of rice husk can extract soluble organic materials through using various types of modifying agents like base and acid solutions. For rice husk, the chemically treated sample showed removal efficiency of 27.8%, while thermally treated samples showed better phenol removal efficiency of about 36.4%–64.9%.

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9.2.5 Plastic waste Day-by-day use of plastics is increasing all over the world. Looking forward in the scenario of present lifestyle, a complete ban on the use of plastic cannot be imagined, although waste plastic is taking the face of a devil for the present and the future generation. Like any other country, waste management is a pressing issue in India, especially with the unceasing growth of consumerism throughout the nation. Plastics are mainly classified into thermoplastics, which can be recycled, and thermoset, which cannot be recycled to produce plastic products after recycling. About 27% of thermoplastics is used in agriculture and about 58% in construction industry for various applications. In India, consumption of plastics per capita is far less than global values per capita. This is mainly due to the cost of the raw materials and inadequate methods and processes available for recycling. In India, 80% of total plastic consumed is discarded as a waste and official statistics say the country generates 9200 tons of plastic waste daily [16]. At least 40% of this waste is uncollected. Interestingly, almost 60% of the total plastic waste generated in India gets recycled while the remaining escapes into the environment [17]. The plastic waste consists of waste generated due to rejection of parts not satisfying the tolerance limits or generated during the process of plastics processing at the factory level. More concern is for the plastic waste generated after completion of useful life or deterioration of the product. The following are some mentioned value-added products of plastic waste. 9.2.5.1 Pipes with partly recycled plastic pipe waste There are a variety of uses of Ag-Plastics like drip irrigation tubing/ laterals, soil fumigation films, drip emitters, irrigation piping, polytunnels, plastic greenhouses, etc. Waste of these pipes is generated due to breakage by rats in the field and faulty production of pipes during manufacturing in the industries. Disposal of this plastic waste is a big challenge because its disposal severely affects the environment. Thermoplastics recycling helps to reduce the cost of the plastic manufactured by partly replacing the virgin raw material in the process with processed waste plastic. Polyethylene is most widely used in Indian industries. Its demand has reached approximately 3.6 million tons per annum. Pipes made of polyethylene such as linear low-density polyethylene (LLDPE) are widely used because of wide adaptability and relatively lower cost [18]. Recycling of the linear low-density polyethylene (LLDPE) and LLDPE blend for manufacturing of pipes can reduce the cost of production as well as mitigate the issue of its disposal to the environment. To achieve these objectives in terms of cost optimization for manufacturing of drip irrigation pipes and improve the productivity, several numbers of formulation

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of virgin LLDPE and recycled LLDPE materials has been studied, and the physical, rheological, mechanical, and morphological properties of virgin and LLDPE blends with field recycled material were analyzed [19]. Use of various analytical techniques help to understand the effect of addition of various percentages of plastic wastes in virgin material. Young’s modulus, hardness, and melt flow index were observed to increase while tensile strength, load at break, and elongation at break shows decreasing trend as compared to virgin material. This happens because of the breaking of intermolecular bonds of polymer material due to processing and weathering effect [20]. The problem of waste disposal of the used pipes could be addressed by recycling even if 20% of waste LLDPE material is reused. It can also reduce the cost of raw material for manufacturing of pipes, which would be easily available at a cheaper rate to farmers. Comparable properties are obtained at 20% usage of recycled LLDPE as compared to virgin material. After a weathering test, tensile strength dropped significantly on further addition of recycled materials over 30% [21]. This helps not only to improve the productivity but also conserve the resources leading to considerable cost reduction in manufacturing of new pipes. As the plastic material is a slow decaying material, increased use of old pipe material or reprocessed factory waste plastic will help to solve the environmental hazard due to dumping of these waste materials. Due to the decrease in cost of raw material, the end product drip irrigation pipes will be available at cheaper rate to farmers. This will enable them to bring more area under drip irrigation and help to make use of water in the most optimum way [21]. 9.2.5.2 Asphalt mix with waste plastic The usage of waste plastics in road construction is nowadays gaining importance because roads with the incorporation of plastics perform better than ordinary ones, and plastic waste considered to be a pollution menace can find its application [22]. They suggested that recycled plastics can either replace aggregates or serve as a binder modifier [23]. Waste plastic has potential for use in bituminous road construction as its addition in small doses (about 5%–10% by weight of bitumen) helps in substantially improving the stability, strength, fatigue life, and other desirable properties of bituminous mixes, leading to improved longevity and pavement performance [24]. Laboratory and field performance studies report that using waste plastic in bituminous mixes increases durability and results in higher resistance to deformation and reduction in water-induced damage, indirectly contributing to user satisfaction and accident reduction [25]. It also leads to a reduction of bitumen consumption, thereby resulting in reduction of costs [26].

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The use of Polyethylene Terephthalate (PET) in asphalt mix used for road construction is gaining importance. Water and soft drink bottles are one of the major wastes dumped, and these are made of Polyethylene Terephthalate (PET). Due to higher cost of concrete roads, most of the road network in India is made up of a Bitumen/Bitumen mix. In the research work [27,28], to upgrade the bitumen mixture properties, waste of PET is utilized to partly replace the bitumen in the bitumen mix. To understand the effect of addition of PET waste in bitumen mix, various trials were done. For experiments, the Marshall Mix Design was used to determine the optimum bitumen binder content. A test for the modified bitumen mix properties incorporating PET waste were carried out. The samples were prepared as per the specifications of the Ministry of Road Transport and Highways [29] used in India. After preparing a Marshall Mix Design, several samples were tested to determine the optimum bitumen content. As per the work done by Raut [30], the best results of Marshall Stability and Flow shows that 6% of bitumen by the weight of aggregates is the Optimum Bitumen Content (OBC). After this, samples were prepared to know the impact of modifying bitumen mixtures partly incorporating PET waste in place of optimum bitumen content. Addition of 5%, 10%, 15%, and 20% of PET by weight of the optimum binder content (6%) were tested. It was found that optimum PET addition of 10% gives good results. Composition with 10% PET waste gives good stability with 11.87kN, 2.35 g/cm3 bulk density, 69.33% voids filled with bitumen (VFB) with flow with 2.8 mm, 5.86% air void (AV), and 19.13% void of mineral aggregate (VMA). The results demonstrated that PET addition gives better designing properties. Thus, 10% PET by weight of bitumen is recommended for improving the performance of a bitumen mix. This measure works as the modifier of bitumen in conventional mix to increase the Marshall Stability and Flow [30]. 9.2.5.3 Cement mortar and concrete with thermoset plastic waste Day-by-day, there is a scarcity of natural fine aggregates due to a reduction in availability and restrictions in sand quarrying from natural sources. Bakelite is an early plastic. It is a thermosetting phenol formaldehyde resin formed from condensation reaction of phenol with formaldehyde. The growth of Bakelite consumption increases Bakelite Waste. Bakelite Waste is prohibited from disposal through direct landfilling and open burning, which becomes a waste management problem. Most thermosetting waste material is sent to landfills despite the significant environmental impact caused by disposing of it in this way. The utilization of the waste Bakelite plastics as replacement of crushed stone sand in concrete is promoted. This ensures not only conservation of the natural resources but also helps to address the issue of disposal of waste Bakelite, without any environmental hazard or side effects.

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Waste Bakelite powder was used as a replacement of crushed stone sand. Portland cement with fly ash was mixed with the aggregates to produce the concrete composites. Through work done by Sudhanshu [31], Grade M25 concrete design strength and 0.65 w/c ratio was used for the experiment. Four weight fractions of 0%, 5%, 10%, and 20% of Waste Bakelite plastic were used to replace the fine aggregate in batching [31]. The main objective of this study was to reduce the wastage of plastic and improve the ecofriendly environment. The compressive strength and split tensile of the concrete specimens were determined after 7 and 28 days. The result revealed slump, compressive strength, and split tensile strength of concrete decreased with increase in the percentage replacement of plastic. For 10% addition of Bakelite waste, the decrease was comparatively less. Hence, the cement mortar with 10% Bakelite waste can be utilized for making garden fencing posts, pots for plants, and construction of walkways in the garden or low-cost flooring. The optimum percentage replacement is 10% of Bakelite powder in place of sand in the concrete mix. With this, compressive strength of conventional concrete decreased by 18% and 9.84% after 28 days and 45 days, respectively [31]. Split tensile strength of conventional concrete decreased by 33.69% and 23.45% after 28 days and 45 days, respectively. Hence Bakelite powder, with 10% of replacement in the concrete grade of M-25, can be used for any nonstructural work without any problems. It can be used as Plain Cement Concrete (PCC) or find applications in base or subbase courses in concrete roads, low-cost flooring, floor tiles, and pathways in gardens and communities. Higher replacement of 15% of crushed sand with Bakelite powder can also be easily and effectively used in one grade lower than M-25 concrete mix, i.e., used in concrete of M-20 grade, with the same previous mix design of M25 grade. Apart from these benefits, it is also concluded that the use of waste Bakelite, which cannot be recycled to produce plastics, if used in concrete, provides some other advantages too, like reduction in the use of natural resources, disposal of wastages, prevention of environmental pollution, and energy savings.

9.3 Concluding remarks The activity of utilizing waste from one industry, converting it into useful raw material, and using it in a scientific way to solve a range of environmental waste problems is an excellent example of sustainable waste management. This will help in reducing the liabilities in land occupied by all these industrial wastes. Blending supplementary cementitious

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materials to produce blended cements and cement composites will not only reduce the raw material required for manufacturing cement but also help to conserve the environment. Reduction of cement content in cement composites will reduce carbon emissions and energy consumption in cement production. The disposal of plastic wastes is a major environmental concern worldwide. The plastic segregation at the source itself is the most important step in managing plastic waste. The regional imbalance and cost of the plastic waste transportation can be reduced by using value-added plastic waste products. The efficiencies of the manufacturing industries of the products should be improved minimizing the waste generated in the process. Importance should be given to value-added products from thermoset plastics, which cannot be reused to produce plastic products blended with virgin plastic material. Buildings have an enormous impact on the environment, human health, and the economy. Nowadays, focus is on sustainable development and developing projects that will use natural resources and reuse waste materials minimizing the environmental pollution. The successful adoption of green strategies can maximize both the economic and environmental performance of buildings. In the concept of Green Building, efficiency of green building has four major pillars, namely Structural efficiency, Water efficiency, Material efficiency, and Energy efficiency. LEED is a green building certification program used worldwide. The reuse of the industrial waste products will help us develop green buildings satisfying all the efficiencies and help buildings achieve green status. To reduce the greenhouse gases as well as to overcome the shortage of various materials, this sustainable approach of value addition is necessary. All the previously mentioned value-added products made of industrial waste fly ash, GGBFS, phosphogypsum, red mud, rice husk ash, and plastic waste can be green alternatives to cement composites and other construction materials. More importance should be given for the research and development in this area for sustainable development.

Acknowledgment The authors thank research students from our research group, Manoj P Deshmukh, Avinash Phirke, Dr. Rahul Zambare, Abhijit Aher, Jignasha Bambhaniya, Deepak Sudhanshu, Avinash Raut, Vibha Agrawal, and Dr. Lokesh Ramteke for the research work in the value-added products using industrial waste.

References [1] S. Yoshizawa, M. Tanaka, A.V. Shekdar, Global trends in waste generation, in: I. Gaballah, B. Mishar, R. Solozabal, M. Tanaka (Eds.), Recycling, Waste Treatment and Clean Technology, TMS Mineral, Metals and Materials Publishers, Spain, 2004, pp. 1541–1552(II).

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[2] Central Electricity Authority report, November 2020. https://cea.nic.in/old/reports/ annual/annualreports/annual_report-2020.pdf. (Accessed 30 August 2021). [3] A.K. Jain, Use of industrial by products in concrete and quality assurance in production of blended cements, in: At 29th Conference on Our World in Concrete & Structures, Singapore August 2004, 2004. [4] D.D. Sarode, Fly ash based cement composites for sustainable development, in: Fly Ash Utilization for Sustainable Environment Management, SIES, Nerul, Navi Mumbai, 2014, ISBN: 13: 978-81-929052-0-4. [5] D.D. Sarode, P.R. Nemade, V.H. Dalvi, S.M. Sontakke, R.S. Zambare, N.V. Mukadam, U.K. Baviskar, A Water Resistant Phosphogypsum Composition. (Patent no. 336119) Filed on 15th Dec 2014 with Application No. 4024/MUM/2014, 2020. [6] G. Power, M. Grafe, C. Klauber, Review of Current Bauxite Residue Management, Disposal and Storage: Practices, Engineering and Science. CSIRO Document DMR-3609, 2009. [7] N. Zhang, H. Sun, X. Liu, J. Zhang, Early-age characteristics of red mud–coal gangue cementitious material, J. Hazard. Mater. 167 (2019) 927–932. [8] P. Zhuhai, L. Cheng, Y. Lu, N. Yang, Hydration products of alkali-activated slag-red mud cementitious material, Cem. Concr. Res. 32 (2002) 357–362. [9] M.P. Deshmukh, D.D. Sarode, Utilization of waste from alumina industry for development of value-added products in construction: some review, in: Presented at International Conference on Advances in Materials and Product Design, on 10th Jan 2015 at Department of Mechanical Engineering at Sardar Vallabhai National Institute of Technology, Surat, 2015. [10] M.P. Deshmukh, D.D. Sarode, S.S. Pendhari, I. Alam, Partial replacement of cement in mortar with red mud and ultrafines, in: Selected for presentation in R N Raikar memorial International Conference and Bantia-Basheer International Symposium held in Mumbai on 18-19th Dec 2015, 2015. Paper published in proceedings on pages 349 to 353 in Volume II published by India Chapter of American Concrete Institute, Mumbai, India with ISBN 81-86876-16-2. [11] M.P. Deshmukh, D.D. Sarode, A. Chaube, Effect of partial replacement of crushed fine aggregates with an industrial waste (red mud) on chloride penetration of concrete, Int. J. Curr. Eng. Technol. 6 (2014) 4026–4029. [12] S. Hongfang, C. Chuyu, L. Li, A.M. Shazim, D. Zhu, L. Weiwen, T. Lu-Ping, X. Feng, Synthesis and properties of red mud-based nanoferrite clinker, J. Nanomater. 2019 (2019), 3617050. 12 pages https://doi.org/10.1155/2019/3617050. [13] L. Wang, H. Guangyan, L. Fei, Y. Tong, T. Honghu, H. Haisheng, Y. Yue, L. Runqing, S. Wei, Application of red mud in wastewater treatment, Fortschr. Mineral. 9 (2019) 281, https://doi.org/10.3390/min9050281. [14] B.G. Purnell, Mud disposal at the burntisland alumina plant, in: R.E. Miller (Ed.), Light Metals 1986, TMS, Warrendale, PA, 1986, pp. 157–159. [15] Z. Yanping, Y. Tiankui, Rice husk, rice husk ash and their applications, in: L.-Z. Cheong, X. Xu (Eds.), Rice Bran and Rice Bran Oil, AOCS Press, 2019, pp. 207–246, ISBN: 9780128128282. [16] CPCB, CPCB Report, 2018-2019. https://cpcb.nic.in/uploads/plasticwaste/Annual_ Report_2018-19_PWM.pdf. (Accessed 30 August 2021). [17] A.O. P. M. Europe, An Analysis of Plastics Consumption and Recovery in Europe, 2004. 2004. [18] G. Voxa, R.V. Loisia, I. Blancoa, Mapping of agriculture plastic waste, Agriculture and Agricultural Science Procedia 8 (2016) 583–591. [19] A. Aher, Cost Optimization by Recycling of Linear Low Density Polyethylene Waste to Manufacture Drip Irrigation Pipes (Master thesis June 2016), M.E. Plastic Engineering at Institute of Chemical Technology, Mumbai, 2016.

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[20] J. Bambhaniya, Reuse Potential Assessment of Drip Irrigation Pipes for Sustainable Development (Master thesis June 2019), M.E. Plastic Engineering at Institute of Chemical Technology, Mumbai, 2019. [21] R. Vasudevan, C.A. Ramalinga, B. Sundarakannan, R. Velkennedy, A technique to dispose waste plastics in an ecofriendly way—application in construction of flexible pavements, Constr. Build. Mater. 28 (2012) 311–320. [22] Y. Huang, R.N. Bird, O. Heidrich, A review of the use of recycled solid waste materials in asphalt pavements, Resour. Conserv. Recycl. 52 (2007) 58–73. [23] Indian Road Congress, Guidelines for the Use of Waste Plastic in Hot Bituminous Mixes (Dry Process) in Wearing Courses, Indian Road Congress, India, 2013. [24] Z.N. Kalantar, M.R. Karim, A. Mahrez, A review of using waste and virgin polymer in pavement, Constr. Build. Mater. 33 (2012) 55–62. [25] A.S. Bale, Potential reuse of plastic waste in road construction: a review, Int. J. Adv. Eng. Technol. 2 (2011) 233–236. [26] R. Vasudevan, S. Rajasekaran, Study on the construction of flexible road using plastic coated aggregate, in: Global Plastics Environmental Conference (GPEC), Atlanta, USA, 2006. [27] K. Bhoot, K. Malviya, T.K. Prajapat, Potential reuse of plastic waste in road construction: a review, Int. J. Sci. Res. Eng. 1 (2012) 1–5. [28] T. Khursheed, B.K. Singh, Road construction from solid waste in Jaipur, Int. J. Technol. Res. Eng. 4 (2017) 1711–1714. [29] MORTH, MORTH Specifications for Road and Bridge Works, Indian Road Congress, Ministry of Road Transport and Highways, Government of India, 2013. [30] A. Raut, Study of Asphalt Design Using Recycled Plastic Waste (PET) for Sustainable Flexible Pavement Construction (Master thesis December 2020), M.E. Plastic Engineering at Institute of Chemical Technology, Mumbai, 2020. [31] D. Sudhanshu, Use of Waste Bakelite in Cement Composites (Master thesis December 2020), M.E. Plastic Engineering at Institute of Chemical Technology, Mumbai, 2020.

C H A P T E R

10 Conversion of agriculture, forest, and garden waste for alternate energy source: Bio-oil and biochar production from surplus agricultural waste Dilip D. Sarodea, Rohan S. Oaka, and Jyeshtharaj B. Joshib a

Department of General Engineering, Institute of Chemical Technology, Mumbai, India, bEmeritus Professor of Eminence, Institute of Chemical Technology, Mumbai, India

10.1 Introduction 10.1.1 Present scenario of agriculture waste in India Large volume of agricultural waste is generated annually in all parts of the world as well as in India. Crop residue accounts for 80% of the total dry biomass produced annually. Crop residue produced from agriculture has been traditionally utilized for various rural applications. In developing countries, crop residue is used as fuel for cooking, feed for livestock, or as construction material. Although crop residue is utilized for various traditional practices, large fraction of crop residue is disposed unscientifically. The inefficient disposal of surplus crop residue is because of the cost involved for its collection, transportation and storage. A significant fraction of total biomass produced is left on the farm for open decomposition or burnt. So far, this is considered as a quick, cost effective and

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convenient method for managing the excess agriculture residue on the farm [1]. However, the practices of open burning or open decomposition are not environment friendly. Large amount of pollutants and greenhouse gases are released to the atmosphere annually by these practices. Conversion of agricultural waste to biochar is a promising method for managing the surplus agricultural waste. Biochar is produced from pyrolysis of biogenic waste materials. A wide variety of organic materials have been studied for use as feedstock material for biochar production. Production of biochar from agriculture waste is a promising way to increase the net agricultural production per hectare. The choice of agriculture waste depends on the local conditions, especially the agricultural aptitude of the region. For instance, cotton stalk, sugarcane waste, swine manure and eucalyptus residue are feasible in the agricultural region. Whereas cultivation of cotton, sugarcane, eucalyptus, and swine raring are major agro-forestry occupations and also produce surplus waste biomass [2]. Converting surplus agricultural waste to biochar will reduce the environmental pollution and application of biochar to less fertile soils will improve agriculture productivity. Production of biochar will also provide a value addition to the crop residue and income generation in the rural areas. In India, agricultural wastes have various traditional uses in rural households. For instance, considerable amount of rice straw is utilized as cattle feed, bedding material for animals and as fuel in local cottage industry [3]. Crop residue is used for production of organic manure, which was the primary source of annual fertilizer in traditional agriculture. Organic manure is mainly produced from cattle manure and crop residue is used by considering the requirement in the local community. Use of organic manure also presents various challenges including the cost associated with storage, distribution and field application. There are also environmental problems related to odor, hygiene and ground water contamination [4]. Its use has reduced drastically with adoption of chemical fertilizers and reduction in number of cattle and human resource in villages. Crop residue, especially rice and wheat straw are used for manufacturing of paper and pulp boards. The straw are mixed in a proportion and subjected to bio-methanation for energy generation as well as for manufacturing of paper. Likewise, its use for mushroom cultivation is growing in the recent years [3]. The various competing uses of the crop residue also depend on its type. For example, crop residue from cereal crops is preferred as cattle feed. The heating of boilers in cottage industry and pre-boiling of rice is performed by rice straw and husk. Sugarcane tops are used for feeding dairy cattle or in recent years collected and bailed for the use in agricultural industry. These are burnt openly on field to prepare for ratoon crop in cases of unavailability of collection machinery. Groundnut residue is used as fuel for firing brick and lime kilns.

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Household cook stoves are fueled mainly by residue of cotton, chili, oilseed and pulses. In recent years, some of these ligneous residues are also used in the briquette mixtures in local industries. Similarly, shells of coconut are used as domestic fuel or creating smoke in cattle sheds. Despite these competing usages of crop residue, large amount of surplus residue is generated annually. It is estimated that 65%–70% of the surplus residue is subjected to open burning [5]. This is deemed as the most economical and convenient method to clear the field for subsequent cultivation. The magnitude of open burning has significantly increased in recent years because of reduced demand from traditional sources due to adoption of modern construction material and energy sources for cooking or reduction in household cattle population. The practice of open burning will be discouraged if the waste is converted into a resource that is viable in terms of recovering the cost of collection and transportation. Targeting the use of agricultural waste for biochar production is a logical approach for its effective management. The surplus crop residue will also serve as the most economical source of feedstock for pyrolysis. India is a price sensitive market and therefore cost of feedstock has significant implication on the economic viability of biochar technology. Secondly, this approach does not require change in habit of the rural community as the feedstock sourcing is independent of competing usage of crop residue. This will enable a wider acceptability for the biochar-based technology intervention in rural areas. In this chapter, surplus agriculture waste estimates are adopted from the latest survey undertaken by Technology Information, Forecasting and Assessment Council (TIFAC) [6]. The data on biochar yield, as a percentage of feedstock used for production, is adopted from the published literature for various feedstock materials.

10.2 Literature review 10.2.1 Biochar production from crop residue relevant to India and Maharashtra The amount of biochar produced from certain feedstock depends on the conditions under which pyrolysis is conducted. The amount of biochar produced as a percentage of feedstock is referred to as biochar yield. Biochar yield depends on type of feedstock used, temperature of pyrolysis and reaction time. Various researchers have reported on biochar yield of different feedstock. The present chapter discusses about the crop residue that are available in India and Maharashtra. Gangil and Wakudkar [7] studied production of biochar in a lab scale equipment with vertical cylinder. Biochar was produced through two types of heating system viz. internally heated and with external heating.

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The reactor used in a study was constructed of mild steel and charring was performed in batches, each of 300°C, 350°C, 400°C, and 450°C. The residence time for the pyrolysis was 1 h for external heating (50 L batch) and 2–4 h for internal heating (100 kg batch) type reactor. After charring, the biochar was cooled gradually under ambient conditions. Three types of crop residue viz. pigeon pea stalk, soybean straw and cotton stalk were used as feedstock. The biochar yield or recovery was recorded to be 27%–30%. In case of pigeon pea biochar, higher recovery of 40% was obtained at lower temperature of 250°C and the recovery gradually declined to 21%, with mean value of 30.5%. Hilioti et al. [8] studied biochar derived from castor plant residue remaining after processing the crop for non-edible oil. Castor plant hybrid H14 was grown to produce plant residue after oil extraction. The spent castor cake and castor stalks were used as feedstock. The crop residue was dried and milled to 2 mm particle size to produce biochar with slow pyrolysis. The process was carried out in a vertical tubular stainless steel reactor that was electrically heated in a splittube furnace. The reaction was performed in nitrogen environment provided with a continuous flow of 50 cm3 min
1. The reaction temperature was 550°C attained at a steady heating rate of 20°C min
1. After a reaction time of 30 min, the biochar was removed from the reactor and cooled rapidly at ambient temperature. Biochar yield recorded with castor cake was 30.2% and that with castor stalk was 28.9%. Venkatesh et al. [9] also used castor bean stalk for biochar production. Freshly harvested castor bean plant stalks were threshed to obtain size an average length of 190 mm and 9 mm diameter. The stalks were dried in sun to attain a moisture content of less than 10%. Biochar production reactor was an up-draft type, single barrel vertical kiln. Pyrolysis was undertaken in a temperature range of 350–500°C. Total six types of reaction conditions by the combination of loading rate and residence period were adopted. Three loading rates of 14, 15 or 16 kg were combined with two residence periods each. For loading of 14 kg, residence time of 14 or 15 min was adopted. Likewise, for 15 kg loading, residence period of 17 or 18 min was adopted. Residence time of 19 or 20 min was adopted for 16 kg residence period. The biochar yield varied between 17.1% and 24.4%. At each of the loading rates, biochar yield dropped by 14%–29% with increase in residence period of 1 min. The mean biochar yield obtained by castor stalk pyrolysis was 19.65%. Karaosmanoglu et al. [10] studied biochar produced from rapeseed plant stalks. The feedstock was air dried and milled to particle size less than 1 mm. Pyrolysis was performed in a stainless steel tubular reactor of 220 mm length and 75 mm diameter. Heating was provided through a 5 kW electrical furnace. The reaction was carried out in nitrogen environment. Biochar was produced at various combinations of highest temperature and heating rates. Residence time in all the cases was 30 min. Six type of biochar were produced at heating rate of 5°C min
1 and pyrolysis

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temperature of 400°C, 500°C, 600°C, 700°C, 800°C, and 900°C each. Two more biochar were produced at pyrolysis temperature of 800°C with heating rate of 10 and 15°C min
1 each. Highest biochar yield of 39.36% was obtained at 400°C and the yield linearly declined with temperature with lowest yield of 27.87% at 900°C. A mean yield of 32.15% was obtained at heating rate of 5°C min
1. Biochar yield declined slightly due to heating rate, from 28.23% at 5°C min
1 to 27.11% at 15°C min
1. Lime and White [11] used sugarcane bagasse and leaf residue (tops) as the feedstock for biochar production. Three type of biochar were produced from different sugarcane-based feedstock. Sugarcane leaf residue (tops) and bagasse were obtained from cultivar HoCP 96–504, and whole stalk was obtained from cultivar L79–1002. Each feedstock was dried and milled to 2 mm for use in the reaction. Pyrolysis was performed on a ceramic evaporating dish placed in Lindberg bench furnace aided with retort. Two types of biochars were produced from each feedstock either at 350°C or 700°C. A reaction was carried out under nitrogen environment with a flow rate of 1.6 L min
1 and reaction time of 60 min. The six biochar produced at the two temperature were cooled at ambient conditions prior to characterization. In addition, two more biochar were produced at 650°C from leaf residue and bagasse of cultivar HoCP 96–504. A biochar yield of 45.5%, 40.9%, and 27.3% was obtained from leaf residue pyrolysis at 350°C, 650°C, and 700°C respectively. Biochar yield from sugarcane bagasse was recorded to be 44.9%, 35.4% and 28.3% for pyrolysis temperature of 350°C, 650°C and 700°C respectively. Biochar yield obtained from whole stalk was 43% and 27.9% at 350°C and 700°C respectively. The mean biochar yield from leaf residue, bagasse and whole stalk was 37.9%, 36.2% and 35.5% respectively. Similarly, Melo et al. [12] studied influence of pyrolysis temperature on biochar production from sugarcane straw. Pyrolysis was performed in a lab scale equipment of 1.2 L muffle furnace. Sugarcane straw was oven dried at 60°C for 24 h prior to pyrolysis. The muffle furnace was sealed to prevent the in-flow of oxygen. Four biochar were produced by heating the furnace at the rate of 10°C min
1 to attain reaction temperature of 400°C, 500°C, 600°C, or 700 °C. Reaction was performed as slow pyrolysis with a residence time of 1 h. Biochar was cooled to ambientconditions gradually prior to yield measurement. Highest yield of sugarcane straw was obtained at 400°C, which was 45%. Biochar yield gradually reduced to 31% in case of pyrolysis temperature of 700°C. A mean biochar yield of 37.25% was obtained from sugarcane straw feedstock. Puga et al. [13] also reported on biochar production from sugarcane straw. Slow Pyrolysis was performed at a temperature of 700°C. Feedstock was collected from the field, dried and milled to 2 mm prior to pyrolysis. The muffle furnace reactor was sealed to prevent oxygen entry and applied with a heating rate of 5°C min
1. The reaction was carried out for 1 h and the biochar thus obtained was cooled at ambient conditions

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prior to characterization. A biochar yield of 31% was obtained in the study with sugarcane straw. Economic viability of biochar production depends on the feedstock availability. Biochar is produced from locally available crop residue and agriculture waste. For instance, biochar produced from rice husk, rice straw and pigeon pea steams was studied in Myanmar, where these constitute as agricultural waste in surplus to competing applications. Biochar was produced in a 200 lit diesel barrel. The container was suitably modified to form a top loaded and up draft kiln. The bottom was provided with small holes and feedstock was loaded into the barrel. The barrel was placed on a tin plate with large holes, to allow partial supply of air. The feedstock was ignited from the top. The reaction time varied according to feedstock and the pyrolysis temperature ranged between 550°C and 700°C. Reaction time for rice straw biochar was 35 min, it was 45 min for pigeon pea stem biochar and 8 h for rice husk. Each batch of rice straw biochar weighed 10 kg, pigeon pea biochar weighed 12 kg and rice husk biochar weighed 27 kg. Highest biochar yield of 54% was obtained for rice husk. Biochar yield of rice straw was 30% and that of pigeon pea stem was 29% [14]. Tinwala et al. [15] reported on biochar production using various agro-industry biomass on a bench scale reactor. Biochar was produced from pigeon pea husk (tur), groundnut shell, gram straw, soybean straw and wheat straw. The feedstock was sun dried and milled to a particle size of 0.5–0.6 mm and pyrolyzed at 500°C in a fixed bed reactor. The reactor had a 100 g capacity with 2 kW capacity ceramic band heater. The heating was carried out at the rate of 10°C min
1. Highest biochar yield of 40% was obtained with three biomass viz. wheat straw, gram straw and soybean straw. Biochar yield from groundnut stock was 37% and the lowest yield with pigeon pea stock was 32.5%. Venkatesh et al. [16] studied the use of portable kiln for producing biochar from crop residue. A bottom ignition, updraft oil drum vertical kiln with a capacity of 210 L was used for biochar production. The top of drum has 16 cm  16 cm hole for loading the feedstock with a lid of 26 cm  26 cm. The bottom of the reactor is provided with vents in three equidistant concentric circles. During operation, gray color exhausted correlated with 350–400°C temperature and blue exhaust correlated with 450–500°C. In case of maize stalk, loading rate of 8.7 kg per batch was adopted with partial pyrolysis residence time of 15 min. A loading rate of 10.8 kg per batch and pyrolysis period of 11.3 min was adopted for cotton stalk. Castor stalk pyrolysis was performed with a loading rate of 15 kg per batch and residence time of 17 min. In case of pigeon pea stalk, the loading rate was 18 kg per batch and pyrolysis residence time was 16 min. Highest biochar yield of 35% was obtained with pigeon pea feedstock. Biochar yield with maize stalk, cotton stalk and castor stalk were 29.3%, 26.9%, and 24.4% respectively. Wang et al. [17] studied the influence of temperature and residence

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time on biochar produced from different agriculture residues. Feedstock used in the study included corn stalk, rape stalk, wheat stalk and peanut shells. The samples were washed, oven dried at 60°C for 24 h and milled in a drug pulverizer to obtain a uniform size fraction of ( ZSM5 ð40:4%Þ > YZeolite ð32:6%Þ

(16.5)

Calcium carbide (CaC2) catalyst increases the oil yield by 60% due to the presence of π electrons. These electrons vibrate and enhance the vibrational energy of tires up to resonance and form polymer radicals responsible for depolymerization [48]. Tire pyrolytic oil’s viscosity is two to three times higher than diesel. Also, the nitrogen content is more in pyrolytic oil that leads to NOx emissions. For removal of sulfur from pyrolytic oil stringent hydrotreating is necessary. Different approaches have been developed for waste tire recycling like rubber reclamation, supercritical solvent, etc., but the most widely used method of waste tire degradation is pyrolysis that yields oil to be fractionated into various fractions of gasoline, diesel and other fuels. Naskar et al. [49] reported a method of pyrolysis of waste tire to get carbon black (char) to be used as the anode in Li ion battery. Rubber tires after crushing to powder form were treated with oleum (20% SO3) at 70 °C for 12 h to get sulfonated rubber powder that was then pyrolyzed to get 40% carbon char. Rubber tires mainly contain polybutadiene, polyisoprene and styrene-butadiene copolymer and start degrading at 300–450 °C. The carbon obtained from tire waste when used as anode Li ion battery, 100% coulombic efficiency, and reversible capacity of 390 mAh/g after 100 cycles was observed. Mohan et al. [50] developed a cost-efficient technology of pyrolysis of waste tires in rotating autoclave reactor followed by selective adsorption

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16. Plastic recycling: Challenges, opportunities, and future aspects

of aromatics and sulfur in a silica gel column to yield upgraded oil with a high cetane number of 35 and complete process cost is around Rs. 23.6 per liter of oil. The optimized conditions for the process were found to be reaction temperature 400 °C, speed of agitation 4 rpm and reaction time was 5 h. It was found that about 3.5 tons oil, 1200 kg steel wires, and 2080 kg carbon-rich char were obtained from 8 tons of waste tire feed. During the upgradation process, petroleum ether was used as a diluent and silica gel column for adsorption, 19% reduction in sulfur content was observed. Energy analysis revealed that only 7 kW energy is required for the distillation of oil into diesel fraction. The same group of researchers has patented this technology of upgrading tire oil using petroleum ether as diluent and silica gel having 60–120 mesh as silica gel preferentially adsorbs polar compounds present in the oil [51].

16.3.7 Polyamides recycling Polyamides mainly comprise of fibers and nylon. The most widely used polyamides include Nylon-6 and Nylon-66. Nylon-6 is a polymer of caprolactum synthesized in an inert atmosphere at 533 K to get polycaprolactum or nylon-6 via ring-opening polymerization. Nylon-66 is a semi-crystalline polymer synthesized by adipic acid and hexamethylene diamine monomers via condensation polymerization. 16.3.7.1 Nylon-66 recycling Acid hydrolysis of nylon yields amine salt and carboxylic acids. Whiston et al. [52] used the same concept and patented a process for acid hydrolysis of nylon-66 using tetraalkyl phosphonium chloride ionic liquid as a solvent. Excess sulfuric acid used can also act as a solvent in the process. This IL being hydrophobic, the separation of aqueous sulfate salts from IL at the end of the reaction becomes easy. Sulfuric acid:water:nylon-66 was used as 1:1:1 equivalent and heated to 100 °C. Post reaction, n-hexane was added to separate IL and product mixture. The aqueous layer contains adipic acid and hexamethylene diamine salt. The recrystallization of aqueous phase yields adipic acid. Hexamethylene diamine was simply separated by the addition of a base. 16.3.7.2 Nylon-6 recycling Hydrolytic depolymerization of polyamide waste particularly nylon-6 to recover caprolactum monomer was studied by Nemade et al. [53]. He has studied hydrolytic depolymerization of polyamide waste at temperatures from 235 to 250 °C and at autogenous pressure 480, to 600 psi using 0.5 L high pressure autoclave using NaOH as a catalyst and water as solvent. Around 59.2% maximum depolymerization of polyamide waste into

16.3 Chemical recycling methods for various polymers

335

monomer caprolactum was obtained at 250 °C and 600 psi pressure. After the reaction, toluene was added to the mixture to recover caprolactum. The reaction followed first order reaction kinetics and had activation energy of 90 kJ/mol and a corresponding rate constant 3.2  103 min1. Kamimura et al. [54] studied nylon-6 depolymerization in hydrophilic ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate. Nylon-6, IL and N,N-dimethylaminopyridine was added to the reactor and heated with microwave radiations to an average temperature of 300 °C for 30 min. Post reaction, acetone was added to remove the solid residue and obtain a filtrate. The filtrate when extracted with ethyl acetate gave two phases. The organic phase was washed with water and dried over sodium sulfate and caprolactum yield was over 50% at 310 °C. A company, Aquafil focuses on recycling nylon 6, a polyamide that can undergo hydrolysis. The recovered nylon can be reused for manufacturing their ECONYL yarn, that can then be fed back into textiles [2]. This process first separates any polyurethane if present in the waste. This is done by heating the waste at a temperature of 200 °C for up to 24 h. In the next step, separation of the polyamide fibers from the decomposed polyurethanes is done by washing in a polar solvent, at a temperature of 5–78 °C for up to 10 h. After which the polyamide fibers are dried and purified and can be readily reused. The solvent is separated and purified from the degraded components and is recycled in the process. Kumar et al. [55,56] reported a new Ru pincer complex catalyst for hydrogenation of nylon-6, other polyamides, and polyesters. This catalyst is effective for chemical depolymerization of esters and polyamides as reported by them earlier. The nylon depolymerization was carried out at 150 °C and 70 bar pressure for 48 h in the presence of a complex catalyst in potassium tert-butoxide and dimethylsulphoxide (DMSO) as a solvent. DMSO can dissolve nylon at high temperature like 130 °C. They have also demonstrated that the diols and diamines obtained from the hydrogenerative depolymerization process are used to synthesize the original polyamide via a ruthenium-catalyzed dehydrogenerative coupling process, thus closing the loop of polyamide production.

16.3.8 Polyethylene and polypropylene recycling Resin identification code: LDPE 4, PP 5 Low density polyethylene (LDPE) is synthesized by the addition polymerization reaction with ethylene (CH2]CH2) as a monomer repeating unit. LDPE is mainly used in thin films, single use polyethylene, tubing, dispensing bottles, etc. LDPE is semi-rigid and translucent thermoplastic having flexibility and branching. Polypropylene (PP) is a thermoplastic polymer of propylene (CH3dCH]CH2) and is synthesized by addition

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polymerization in presence of Ziegler Natta or metallocene catalysts. Polypropylene is partially crystalline and non-polar and is mainly used in packaging for consumer products, automotive parts, hinges, and even in textiles. The utilization of renewable energy resources is the need of the hour. The non-depleting energy sources like solar energy, wind energy, and tidal energy must be utilized as we are facing an energy crisis. On the same principle, Jiang et al. [3] utilized solar energy in combination with a chemical reaction called solar thermal electrochemical process (STEP) for PP recycling. An electrochemical cell having both electrodes of nickel with about 1 cm spacing and NaOH and KOH as electrolytes were used as an electrochemical reactor for PP degradation. A simple solar to thermal heat concentrator, a photovoltaic (PV) module, and an electrochemical reactor was used. The PV module should generate 5 V and 1 A current to be supplied to the reactor. The reactor temperature was maintained at 350 °C for 60 min giving 66.64% conversion of PP. The anodic and cathodic reactions for the same are described as per Eqs. (16.6) and (16.7): Anode : PP + H2 O + ne ! RCH3 + CH4 + C2 H6 + ⋯ + H2 + oxygenated compounds (16.6) n Cathode : nH+ + ne ! H2 2

(16.7)

Thus mainly gases were evolved and a large amount of hydrogen evolution takes place at the cathode due to water splitting that pyrolysis alone won’t produce. This H2 can then be utilized for energy production. Hence, the by-products are also completely utilized producing no waste streams and achieving the atom economy. Process intensification by ultrasonic sonochemistry has been an interest of researchers these days owing to simple reaction set up and less power consumption. Desai et al. [57] studied PP depolymerization in an ultrasonic reactor using xylene and decahydronaphthalene as solvents. The ultrasonic irradiation leads to the formation, subsequent growth and violent collapse of bubbles due to which ultra-high temperature hot spots and radicals are generated that create liquid turbulence. The power rating of the ultrasonicator used was 240 W out of which 15.5 W was used. The viscosity of the polymer post reaction was a measure of concentration and degradation. Faster degradation was observed in p-xylene due to low viscosity and low surface tension because as surface tension increases the resistance increases. The higher cavitational intensity was observed in p-xylene. Surface active agents commonly called surfactants are used to decrease the surface tension between two liquids, gas–liquid or solid–liquid.

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337

Here, a decrease in surface tension of solid–liquid is of interest as a polymer being solid and solvent being liquid. The surfactants can act as wetting agents, emulsifiers, foaming agents, detergents and are used in cosmetics, cleaning agents, etc. On similar lines, Vasconcelos et al. patented a technique involving surfactant-assisted depolymerization of PE and PP. The surfactant used was cationic surfactant viz. hexadecyltrimethyl ammonium bromide (CTAB) and superacid catalyst Fe2O3/ H2SO4 [58]. The temperature required for pyrolysis is 700 °C or more but here with surfactant and catalyst, the degradation temperature drops to around 200 °C. The solvent used for the process was D-Limonene that is widely used for various chemical processes as a green solvent. For PP depolymerization the reactor temperature was kept 180 °C with a reaction time of 40 min. After completion of the reaction, 10% lignin was added to increase the viscosity of the product mixture that contains oligomers. A similar method can be adopted for PE that depolymerizes at a lower temperature 150 °C in 30 min but requires additional ferric sulfide reagent. When solvent: surfactant ratio was 50:30 (by volume), the reaction yield improved by approximately 90%. As mentioned above, the synthesis of these polymer uses the Ziegler Natta catalyst or metallocene catalyst. So, the same catalysts can be utilized for recycling these polymers by converting them into plastic crude oil to get petroleum products. Swaminathan [59] patented a catalyst for decomposing plastic waste. Metallocene catalysts can be formed by complexing Ti, Zr, Hf with two organic ligands. PdCl2 impregnated on 13X molecular sieve, and then dried at 110 °C. Further Sodium borohydride in water was then combined with the molecular sieve so that PdCl2 reduces to Pd. After which the sieve was again dried. The pore having Pd was then again impregnated with bis-cyclopentadienyl zirconium in toluene and the sieve was dried further for 24 h. This molecular sieve was then utilized for PE and PP degradation at 450 °C. It was observed that at around 380 °C, the products start to distill and can be analyzed by GC– MS. Fig. 16.1 shows the combination of impregnators on the molecular sieve and corresponding yield of gasoline and diesel. Considering the cost of molecular sieves and elements like Pd, Zr, Hf the process gives good results but is not economical. Zhang et al. [60] synthesized jet fuel from waste LDPE using activated carbon as a catalyst. The reaction was ex situ catalytic pyrolysis carried out in a fixed bed tube reactor for easy separation of pyrolysis residue and catalyst. The reactor was operated at various temperatures 430 °C, to 571 °C and it was found that 500 °C was the optimum temperature to get 73 wt% pyrolysis oil, 24 wt% gas, and 2.9 wt% coke. Zhang et al. [12] used 1.5 wt% Pt (1 nm particles) dispersed on γ-alumina as a catalyst for depolymerization of low molecular weight

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Molecular sieve based catalysts 95

100

% yield

80 60

59

52

48 41

40 20

5

0 Pd

Pd-Zr

Zr Gasoline

Diesel

FIG. 16.1 Yield of gasoline and diesel with different promoters on molecular sieve catalysts for PE-PP [59].

polyethylene—LDPE and HDPE at 280 °C and 24 h of reaction time without any solvent or H2 pressure to yield a variety of alkylaromatics like toluene (47 wt%), n-hexane, cyclohexane, benzene, methylcyclopentane, n-heptane by distillation and gases like hydrogen and C1–C8 fractions were as well obtained. Yao and Wang [61] developed a technique for depolymerization of polypropylene that would yield gases and the carbon residue comprises of carbon nanotubes in the range of 15–30 nm. The methodology used was catalytic pyrolysis using Fe, Ni, and bimetallic Fe–Ni catalysts prepared by sol–gel synthesis method with aluminum tri-sec-butoxide (ATB) and metal precursors. In a quartz tubular reactor at 500 °C with all the catalysts gives about 44% gas, 46% liquid, and 4% solid residue. Mostly methane was obtained followed by hydrogen. Fe–Ni bimetallic catalyst gave the highest H2 yield (25.14 mmol/g plastic) and highest carbon deposits (360 mg/g plastic). With only Fe catalyst multiwalled carbon nanotubes were obtained.

16.3.9 Polyurethane foam recycling Resin identification code: OTHERS 7 Polyurethane (PU) foams being flexible are widely used in variety of consumer and commercial applications like bedding, furniture, automobile interiors, carpets and even in packaging material. The annual growth of PU foams is around 84% globally and the business of PU foams is expected to rise to US $74.21 billion by 2021. Diisocyanate when reacts

16.3 Chemical recycling methods for various polymers

339

with the hydroxyl group of polyols, urethane linkages are formed giving polyurethane. Thus post recycling, recovery of polyols proves to be a better option and these polyols can then be utilized for other chemical processes like the production of inks, paints, flexible foams, fibers, elastomers, etc. Various methodologies like glycolysis, aminolysis, and ammonolysis have been adopted for recycling PU foams. 16.3.9.1 Glycolysis and hydrolysis For glycolysis of PU foams, diethylene glycol, and diethanolamine when used as a co-reagent the polyols obtained have low reactivity and high viscosity. It was found that equimolar quantities of ethylene and diethanolamine (DEA) gave the fastest glycolysis reaction rate. The catalysts used in glycolysis can be inorganic acids, phosphorous compounds, phosphoric esters, alkaline hydroxides, carboxylic acids, etc. For recovery of flexible and rigid polyols, the double recovery method also called as split-phase glycolysis (SPG) is used. After the reaction is complete, two layers are obtained—the top layer has non-depolymerized foam and the bottom layer has methylene diphenyl diisocyanate (MDI) derived compounds. MDI when reacted with polypropylene oxide gives high-quality rigid foams. Thus the recycled product is completely used and the circular economy is achieved. In SPG, diethylene glycol (DEG) used gives high purity. In SPG, DEG along with DEA in presence of NaOH gives homogenous polyols in the upper phase that could be then used in making new foams. DEG, sorbitol, and water can also be used in glycolysis that forms ternary green solvent system. It was found that when glycerin and NaOH are used for depolymerizing PU foam at 170–190 °C and 1 bar pressure yields high quality polyols and it possible to replace 40% of virgin polyols with these recycled polyols and other products [62]. Uliana et al. [63] studied the kinetics of PU foam depolymerization in D-limonene as a green solvent and KOH that revealed that the process is a decarboxylation reaction releasing carbon dioxide, polyol, and diamine at optimized conditions of 175 °C and 40 min reaction time giving 99.97% PU conversion. The kinetic and thermodynamic study reported the values of activation energy, enthalpy, entropy, and Gibbs free energy to be 96.5 kJ/mol, 93.2 kJ/mol, 753.4 J/K mol, and 208.2 kJ/mol, respectively. 16.3.9.2 Aminolysis and ammonolysis Polyurethane foams are mainly of two types viz. polyester-based and polyether-based. Aminolysis uses amines and the reaction is carried out at room temperature, atmospheric pressure and recovers original polyols and some distributed urea products are present. As compared to ammonolysis, aminolysis is a bit slower due to less basicity of nitrogen. Aminolysis takes place in two steps. In the first step, depolymerization of PU takes place

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16. Plastic recycling: Challenges, opportunities, and future aspects

to get a highly concentrated emulsion with urea, carbamates, polyols, and amines shown in Eq. (16.8) In the second step, the mixture is alkoxylated to get high functional polyols by removing aromatic amine. 2NHðROHÞ2 + R’ NH  COOR’’ Ð R’ NH  COOR  NHROH + R’  NH  CO  NROH + R’’OH (16.8) Hydrolysis as compared to aminolysis generates CO2 and the reaction pressure required is above 16 bar so generally is not adopted. Ammonolysis can take place in presence of concentrated ammonia water solution, i.e., NH4OH. Strong basic catalyst increases depolymerization. If supercritical ammonia is used, gives good separation of polyols by distillation [64].

16.3.10 Recycling of mixture of waste polymers Generally, when waste is generated there exist not one polymer but it is a mixture of polymers. Sometimes it is difficult to segregate the polymers according to their nature, color, density, type, etc., or is economically not viable then it is better to recycle the mixture to obtain useful products. Sutar [65] patented a process for the recycling of mixture of waste polymers using catalyst with promoters. The details of study is summarized in Table 16.3. TABLE 16.3 Recycling mixture of polymers with catalysts and additives [65]. Mixture of polymers

Reagents used

Products

PET, PVC, PE, PP, LDPE, ABS polymer, foam, and synthetic fibers

Catalyst: 20 (w/w) alumina, 20 (w/w) silica, 20 (w/w) calcium oxide, 20 (w/w) calcium silicate, and 20 (w/w) aluminum silicate Additive: 20% ammonium chloride, 20% ammonium sulfate, 20% ammonium acetate, 20% ammonium carbonate, 10% ammonium phosphate, and 10% calcium nitrate

Temperature ¼ 380 °C, 70% (w/w) oil in the distillate that mainly comprised of C6–C10 fractions and olefins 8% (w/w) gases evolved

PET bottles and PVC pipes

Catalyst: 40 (w/w) copper oxide and 60 (w/w) aluminum silicate Additive: 30 (w/w) ammonium formate, 30 (w/w) sodium nitrate, and 40 (w/w) calcium sulfate

Temperature ¼ 350 °C, 50% (w/w) oil in the distillate and 10% (w/w) gases evolved

16.3 Chemical recycling methods for various polymers

341

The mixture of plastics thus can be utilized to get plastic crude oil that can be then distilled. Efforts continue to use a cheaper catalyst that could be regenerated easily. Senthil Kumar et al. [66] studied depolymerization of a mixture of PP, PE, and PS using activated carbon and charcoal as a catalyst at 240 °C and 0.4 bar in a semi-batch reactor. 98% oil yield was obtained with charcoal as a catalyst that can be distilled to get gasoline, diesel, and motor oil as products. The spent catalyst was dissolved in water and then heated to 80 °C, filtered and dried again to regenerate it. Streiff et al. [67] patented a catalyst composition for depolymerization of PP and PE to yield petroleum fuels as products. The reactor temperature was maintained at 425 °C. The catalyst used was FCC catalyst which is generally used in petroleum industries containing about. 75% FCC and 25% SiO2. In 14 min of reaction time, 89.25% conversion was observed. The plastic crude oil when distilled gave gasoline, kerosene, diesel, and gaseous fractions with a selectivity of 40%, 30%, 18%, and 5.3%, respectively. Hydrogen and hydrogen-containing compounds are nowadays used in a variety of energy applications, have high energy efficiency, and environmental benefits. Keeping this view in mind, Jie et al. [68] converted a mixture of plastics including HDPE, LDPE, PP and PS into hydrogen and multiwalled carbon nanotubes using FeAlOx catalyst (microwave susceptor) in a microwave reactor at a frequency of 2450 MHz and having a maximum power rating of 2000 W. The catalyst FeAlOx was synthesized using the citric acid combustion method with iron nitrate (III) nonahydrate and aluminum nitrate nonahydrate as precursors. The catalyst particles and mechanically shredded plastics were manually mixed in the weight ratio 1:1. One step rapid transformation of plastics into multiwalled carbon nanotubes and H2 was observed at 560 °C in 30–90 s and about 55.6 mmol hydrogen per gram of plastic was obtained in the process. Chevron Philips Chemicals (CPChem) has started commercial production of circular polyethylene from the mixture of waste plastics in the United States and the specifications of the circular polyethylene matches the performance and safety specifications of the virgin polymers; this newly developed polyethylene is marketed with the commercial name Marlex Andrew Circular Polyethylene [69]. This patented technology includes the collection of waste plastics, the formation of plastic bale, pyrolysis to get pyrolysis oil, cracking in the PE cracker to get PE pellets that could be then converted into a variety of other consumer goods and packaging material. Fig. 16.2 represents few important and economically viable processes of depolymerization of various polymers based on the literature survey. These processes provide environmentally friendly solutions for recycling of plastics and are also scalable.

342

16. Plastic recycling: Challenges, opportunities, and future aspects

es

C8-C12 gasoline at 28-240°C.

Pyrolysis

92 % plastic crude oil

M ix

Liquefaction LCO and HCO assolvents

Recycling Waste Plastics and Polymers

H

90 wt% C3-C5 and 40 wt% C6-C7 Reactive Distillation HZSM-5 catalyst 99.8% BPA

Methanolysis Catalytic Pyrolysis Choline chlorideCharcoal and Activated urea DES catalyst 99% Carbon as terephthalic acid catalyst Methanolysis re DCM solvent and NaOH Po e l ye t hylene Terephthalat

tu

FIG. 16.2

72-79% Styrene

Po lyc ar bo nat e

S +P PP PE+

Process/Reagents

Polymer to be recycled

E DP

W as te Ty r

tyrene Polys

Optimized depolymerization methods for different polymers.

16.4 Applications and properties of recycled polymers Chemical recycling is the most viable and environment-friendly technique for disposal of plastic waste and recovery of monomers. These recycled polymers that contain their respective monomers can be further utilized to produce the polymer. Many times, some external agents can be blended with recycled polymers and can be further utilized for a different application.

16.4.1 Additives in recycled polymers and polymer composites: A way to enhance material properties Nanomaterials offer a cornucopia in plastics reinforcing. The addition of nanomaterials to recycled polymers helps develop rigidity, strength, thermal and chemical resistance, etc. Lo´pez de Dicastillo et al. [70] reviewed all types of nano-additive materials as additives in recycled plastics and developing nano-reinforced plastics as new, safe, and sturdy

16.4 Applications and properties of recycled polymers

343

packaging materials for the food industry. Different types of blending techniques can be utilized for developing recycled plastics. Nanomaterials in a very small concentration can drastically affect the properties of the recycled polymers. Recycled polystyrene when reinforced with nano silica by extrusion and injection molding process gives flexural and tensile strength to new PS developed. Similar properties are observed when TiO2 is incorporated in r-PS. The r-HDPE when added upon with graphene nanoflakes by solution blending and injection molding at 288 °C significantly increases elastic modulus, thermal resistance, and optical properties of the new HDPE developed. Graphene being 100 times stronger than steel, when added to the recycled polymers due to ease of dispersion, greater surface area and superior mechanical, optical, and thermal properties alter the properties of the polymer significantly. Nano-clays like montmorillonite (MMT) are widely used clay in packaging thermoplastic polymers. These clays enhance rigidity, yield stress, tensile modulus and resistance to humidity. r-PP when mixed with modified Tunisian clay in presence of trimethyl octadecyl ammonium bromide salt as a surfactant by melt blending process at 180 °C, gives better thermal stability to the new PP. r-HDPE along with graphite can be used to develop medium temperature thermal energy storage material [71]. Patel et al. [72] utilized recycled LDPE and egg-shell powder as a filler to enhance the material’s mechanical properties. The egg-shells and r-LDPE were put into a single screw extruder at 190–210 °C. The different weight percentage of egg-shell powder was used and mechanical properties were tested. They found that 15 wt % egg-shell powder showed the best results. It showed the tensile strength of 0.020 MPa whereas only r-LDPE showed a tensile strength of 0.007 MPa. Similarly, Young’s modulus with filler was 2 and 1 MPa for r-LDPE alone; elongation at break was 22.5% for r-LDPE along with filler and 35% for only r-LDPE alone. Plastic fiber insulations can be made from recycled milk pouches, PET bottles that can be further treated with fire retardants to develop resistance to flames [73]. Recycled rubber floors are widely used for making small footpaths, walkways, and other small-scale applications. We know that bitumen is material with high aromatic content obtained from the petroleum industry that is used in making roads. This bitumen can be then further modified with recycled polymers to develop polymer modified bitumen (PMB). Joohari and Giustozzi [74] studied various properties of PMB with different polymers and it was found that recycled linear low density polyethylene gives the highest softening point and lowest penetration index of bitumen. Plastics being flexible and having some rigidity and elasticity, can very well have applications in automotive, transportation boxes, building materials, and furniture. Basalp et al. [75] synthesized wood plastic composites (WPC) from wood waste and recycled polypropylene and polyethylene. Maleic

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16. Plastic recycling: Challenges, opportunities, and future aspects

anhydride as compatibilizer and 30% wood floor when added to recycled plastics and wood waste in Torque Rheometer at 185 °C gave a wood plastic composite. It was found that PP based WPC had high tensile strength than PE-based WPC. Akbar and Liew [76] synthesized cement-based materials using recycled carbon fibers in the cement and silica fume waste that decreased the cost by 70%, reduced the CO2 emissions by 13.69% and around 222% renewable energy could be saved using this recycled carbon reinforced composite material. Also when 1% recycled carbon fiber is added, it increases the elastic modulus by 57% and tensile strength by 188%. Vanapalli et al. [77] developed a plastic-eucalyptus wood char composite that proved to be the best for seed germination and improving soil properties. Polystyrene waste along with eucalyptus wood as biomass was pyrolyzed to obtain the char with 33% yield in 90 min at 300 °C. With biomass to PS ratio of 2:1 more content of nitrate nitrogen and phosphate was found in the char—the two being essential for plant growth and improving soil properties. High nitrogen content (8.26%–10.7%) is obtained due to plasticizers, compatibilizers, and stabilizers used in the production of PS. Rane et al. [78] have synthesized polyetheramide-polyaniline composite from recycled PET and jatropha oil. Polyetherimide is one of the best anti-corrosive coatings. The fatty amide of jatropha oil (R-CO-N (CH2CH2OH)2) needs to be synthesized by the reaction of triglyceride with diethanolamine (NH(CH2CH2OH)2) in presence of sodium methoxide (CH3ONa) as a catalyst as per Eq. (16.9) Triglyceride + 3NHðCH2 CH2 OHÞ2 ! 3R  CO  NðCH2 CH2 OHÞ2 + Glycerol (16.9) PET when depolymerized with ethanolamine in presence of zinc acetate catalyst at 160 °C gives bis(2-hydroxyethyl)terephthalamide (BHETA). This BHETA product and fatty amide in 50:50 M basis when combines with resorcinol gives polyetherimide an anticorrosive coating. Plasticizers are used in various polymers and other materials to improve flexibility, plasticity and decrease friction for easy manufacturing and handling purposes. More et al. [79] have shown efficient use of recycled PET to synthesize plasticizer for PVC. PET when depolymerized with ethanolamine in the presence of sodium acetate and zinc acetate as catalyst give bis(2-hydroxyethyl) terephthalamide. This product, when combines with heptanoic acid in the molar ratio 1:2.5 and in presence of sulfuric acid (0.5%, w/w) at 200°C gives plasticizer. PVC and plasticizer when fused using a two-roll mill at 180 °C, give high elongation, high tensile strength, and high deflection as compared to virgin PVC. Plasticizer concentration 15 phr (parts per hundred resin) gives the best PVC-plasticizer fused material with enhanced properties.

16.4 Applications and properties of recycled polymers

345

Gama et al. [80] performed acid hydrolysis of polyurethane foams to obtain polyols that can substitute the conventional petroleum-based polyols by 20%–30% (w/w). PU foams along with dicarboxylic acid (succinic, phthalic, and adipic) at 195 °C and 5 h of reaction time yield polyols. Substituting these polyols while synthesizing polyurethane foams, enhances the mechanical properties of the foam. When 10% (w/ w) recycled polyol added it gave Young’s modulus of 1745 kPa and that with 100% conventional polyols was 1965 kPa; similarly, the thermal conductivity of recycled polyol-based foam was 0.041 W/mK and that with conventional polyols-based foam was 0.038 W/mK; the toughness of recycled polyol-based foam was found to be 15,899 J/m3 and that with conventional polyol-based foam was 18,151 J/m3.

16.4.2 Recycled polymers in food industry The majority of the thermoplastic polymers are used in the food industry for the packaging of foodstuff. These plastics prevent any kind of damage to the food due to moisture, heat, or any external food-harming agent like microbes. It can be seen that recycled plastics can have some kind of contaminants that can migrate to the foodstuff when used as a packaging material. This is because, before recycling the plastics may have been used for storage of weed killers, toxic chemicals, pesticides, oil, etc. Therefore post recycling some traces of such harmful materials if any may be present in the products. Many industries often adopt secondary recycling that includes the collection, sorting, chipping/cutting, washing, remelting, and directly converting the material to food packaging. Many industries have come up with technologies sorting waste plastic to be recycled for food industries. PRISM—Plastic Packaging Recycling using Intelligent Separation Technologies—is a consortium of UK-based companies that has come up with a novel technique of sorting food grade HDPE and PP using luminescent labels on plastic packaging and these labels are developed using discarded fluorescent lamps thus a way to manage electronic waste [81]. Any waste plastic that is recycled by chemical means can have many a times an undeterminable composition of products because during depolymerization random scission, radical attacks can form undesirable components. Any plastic when manufactured, compatibilizers are added as additives in the blending process. These additives may break down during depolymerization or may be present in the original form in the recycled polymer. To avoid any kind of harm due to the migration of contaminants in food, some migration tests are conducted when packaging of recycled

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16. Plastic recycling: Challenges, opportunities, and future aspects

polymer used in the food industry. It is expected that the finished material should have a migration limit of 60 mg/kg if the food is stored in a packet for more than 24 h within a temperature range of 5–40 °C [82]. Most of the food industries use food simulants for migration tests rather than actual foodstuff, the latter being difficult to test every time. Typical food simulants include distilled water, 3% acetic acid in aqueous solution, 15% ethanol in aqueous solution and rectified olive oil. Food industries have to be very clean, need to ensure the purity of the product, sanitized to have the purest and safe delivery of food products. So many industries adopt multilayer packaging in which the virgin polymer is in direct contact with the food and above that there exists multilayered recycled polymer. Many researchers have studied the migration of contaminants or impurities from direct contact material to the food that can be written by Fick’s law given in Eq. (16.10) [83]:   D  t 0:5 (16.10) Mt ¼ 2  Co  π Mt is the mass of substance migrating per unit area (μgm/cm2); Co, concentration of contaminant in the polymer at t ¼ 0; D, diffusivity (cm2/s). A study on recycled polyethylene conducted at CSIR-Central Food Technological Research Institute, Mysore, India revealed that many physiochemical changes occur in the recycled films of milk and other polyethylene bags causing almost double the migration of impurities or additives into the food compared to virgin polyethylene and thus making the packaging unsuitable [84]. Inspite of that, United States Food and Drug Administration (FDA) has issued guidelines for ensuring the safe use of recycled polymers and FDA also has issued “letters of no objection” to several industries and companies in the USA that recycle polymers with specific processing methods for various applications [85].

16.4.3 Other major applications of recycled polymers The National Association for PET Container Resources (NAPCOR) reports that around 25%–29% of recycled PET in the US goes into bottle manufacturing. Fig. 16.3 shows the use of recycled PET for different applications (numbers represent percent contribution). Sheppard et al. [87] studied the synthesis of PU films from PU foams using dibutyltin dilaurate (DBTDL) as carbamate exchange catalyst by twin-screw extrusion. The PU foam (1 g) was dissolved in dichloromethane (DCM) (10 mL) with 30 mg/L dibutyltin dilaurate catalyst. After the reaction resultant polymer was filtered, collected and dried in a vacuum oven to remove DCM solvent. It was observed that a gel fraction of

16.5 Plastic recycling and CO2 emissions

347

r-PET applications

4

Sheets and Film

7 2 24

Fibres Food beverage bottles

25 Non-food bottles Strapping 38 Other

FIG. 16.3

Applications of r-PET and their % contribution [86].

87% PU films was obtained. After which compression molding at 160 °C for 12 min was carried out that resulted in solid films. These PU films are extensively used in infusion bags, biomedical applications, surgical clothes, mattresses, etc., since the films have antifungal and antimicrobial properties.

16.5 Plastic recycling and CO2 emissions According to the 2019 report of Bureau of International Recycling (BIR), chemical recycling of plastic would emerge as the most viable outlet in the coming decade. Thus we majorly have two options—either chemical recycling or incineration, the latter one has some adverse environmental effects like global warming. BIR mentions that 1 ton of recycled plastic can save around 5774 kWh energy, 16.3 barrel of crude oil and 22 m3 landfill space.

16.5.1 Energy recovery Plastics have a high energy content that can be very well converted into heat, electricity, or power by incineration. Plastics can therefore replace coal or fossil fuels for energy. In European countries, 9% of total energy is recovered from waste plastic and this energy recovery can save about 26.37 MJ/kg energy of plastics. Table 16.4 states the heating values of various fuels and waste that can be converted into fuels. Waste plastic to oil is also a good alternative to decrease the stress on conventional crude oil and utilize the waste for the production of fuel. Asia contributes to around 44% share in recycled plastic and plastic waste to oil market. The global plastic to oil market is expected to increase from the US $45 million in 2019 to the US $100 million

348

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TABLE 16.4 Typical heating values of different fuels and plastic [89]. Fuel/Waste

Heating value (kcal/kg)

Plastics

11,000

Heavy oil

9500

Coal

6000–8500

Wood/Paper

4300

Typical municipal waste

1000–1500

in 2027 [88]. 1000 kg plastic recycling saves 698 gal of crude oil, 5800 kWh electricity and 30 cubic yard of landfill space. Some global key players, e.g., Plastic 2Oil, Plastic Energy, Niutech, RES POLYFLOW, Nexus Fuels, Agile Process Chemicals LLP, etc., convert plastic waste into oil.

16.5.2 Impact of plastic recycling on CO2 emissions, greenhouse effect and carbon footprint Sun rays are typically composed of infrared, ultraviolet, and visible electromagnetic radiations that heat the earth and the greenhouse effect of atmospheric gases controls the heat depletion. Therefore a balance of both helps to maintain some average temperature on the earth’s surface. But, nowadays due to excessive emissions of water vapor, carbon dioxide, methane, chlorofluorocarbons, perfluorocarbons, etc., problems like global warming, climate imbalance are observed. A carbon footprint is nothing but summation of emissions of all the greenhouse gases expressed as CO2 equivalent. In the case of plastics, the carbon footprint depends on various factors like type of raw material used, polymerization methods, processing techniques, real use and actual years of use and most importantly type of recycling used post application. Burning 1 ton of PE releases more than 3 tons of CO2. PET incineration evolves 0.2–2.6 tons of CO2 [89]. DuPont Engineering Polymers focuses on polyamide recycling. Performing recycling applications, they have stated that recycled polyamides when further recycled after use, release significantly less CO2 than virgin polyamide recycling. United States Environmental Protection Agency (US EPA) states that the generation of clean and recycled PET resin or HDPE requires 71 trillion Btu less energy than that would be required to produce equivalent tonnage of virgin PET or HDPE [90]. In 2008, 2.1 million tons of CO2 emissions have been saved by recycling PET and HDPE. Recycling the polymers to derive monomers and again utilize the monomers to get the same polymer saves oil and reduces greenhouse gas emissions as compared to that when the virgin polymer is manufactured. In PET recycling,

349

16.5 Plastic recycling and CO2 emissions

we get net benefit of around 1.5 tons of CO2 per ton of PET. It is seen that 100% PET recycling instead of 100% virgin PET production reduces CO2 emissions by 27% [91]. Fig. 16.4 represents the amount of CO2 released per kg plastic burnt and it can be seen that virgin plastic production emits the largest amount of CO2 compared to recycling and incineration. A study conducted at CSIR-National Environmental Engineering Research Institute, Nagpur, India in the year 2020 revealed that incineration of waste plastics of PPE kits generated in the Covid-19 pandemic is a better option than landfill. Though centralized incineration has 3816 kg CO2 equivalent Global Warming Potential (GWP), it significantly reduces the impact with respect to Human Toxic Potential (HTP), Eutrophication Potential (EP), Acidification Potential (AP), Freshwater Aquatic Ecotoxicity Potential (FAETP) and Photochemical Ozone Depletion Potential (POCP) [55,56]. The study revealed that landfill causes 2.1 kg PO4 eq. EP, 23.5 kg dichlorobenzene eq. FAETP, 266.3 kg dichlorobenzene eq. HTP and 1.0 kg ethene eq. POCP impact. Current research at Covestro AG, a German company shows that carbon dioxide emitted during the production of virgin polymers or during incineration can be converted into plastic materials using sophisticated catalysts containing metals like copper [93]. The carbon dioxide reacts with epoxides forming polyether-polycarbonate-polyols that can be then used for the production of polyurethanes. The research in this domain is still on the way and not completely developed for the production of commercial-grade polyurethane. Nowadays there is huge research on the way for developing bio-based plastics from second-generation biomass consisting of lignocellulosic waste. Meeting two-third of global plastic demand with bioplastic Average CO2 emissions

6

4.8

kg CO2/kg

5 4 3 2

2.2 1.25

1 0 Recycling

Incineration

Virgin plastic production

Plastic

FIG. 16.4

Graph showing average CO2 emissions by recycling plastics, incineration, and virgin plastic production [92].

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16. Plastic recycling: Challenges, opportunities, and future aspects

241–316 million tons of CO2 equivalent could be saved [94]. These bioplastics are mainly of two types viz. drop-in plastics and completely new plastics. The drop-in plastics are similar to petrochemical-based plastics but just derived from bio-sources like for instance, PE from bioethanol via bioethylene. The completely new plastics include biodegradable polylactic acid to be used in the place of PET. Polyethylene furandicarboxylate is synthesized from ethylene glycol and furan-2,5-dicarboxylic acid and this polymer has 55% less greenhouse gas emissions as compared to petrochemical-based PET.

16.6 Conclusions and future aspects There is still a great disparity between the generated plastic waste and the amount of plastic that is recycled. Now it is the need of the hour to curb plastic pollution and attain a circular economy. Herein we propose various chemical recycling methods to obtain the monomers and utilize those monomers in the production of newer polymers or as additives in other polymers. As seen above, there are limitations to use recycled plastics in food packaging materials due to the diffusion of impurities and additives causing damage to the food stored in the plastic material. Hence, recycled plastics can be further utilized in construction materials, furniture, and the development of new or same polymer materials. The polyolefins that can be converted into plastic crude oil subsequently distilled into fractions of diesel, gasoline, and other fuel stocks serve as a better option to reduce the stress on landfills and also recover fuels from waste in the present situation of energy crisis and depletion of crude oil stocks. Industrial efforts are continuously going on for recycling of plastics at commercial scale. Despite the problems of segregation, impurities, and disposal of leftover carbonaceous residues, many researchers have achieved almost 100% conversion of waste plastics to monomers or plastic crude oil using various solvents, catalysts, different reactors, residence time, separation processes, etc. But still there is a dearth of advanced approaches in recycling methods to completely convert the mixture of polymers in the solid municipal waste into valuable products. More research efforts are needed to develop newer catalysts for achieving high selectivity, high conversion, and yield; and to decrease the depolymerization temperature in case of pyrolysis of waste plastic. Also, in multilayer packaging, the use of additives should be minimized as it poses a threat during recycling. The multilayer packaging many times consists of more than one type of resin. So, it is better to have a single polymer to ease the process of recycling. 6 R’s—Reduce, Redesign, Remove, Reuse, Recycle and Recover [94] is what we must follow in the coming future to attain

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circular economy and sustainability. To conclude with, new developments in chemical recycling, design of newer plastics, and pertaining to green chemistry is the way forward for sustainable development and to control plastic pollution.

Acknowledgments Financial support from, CSIR Bulk mission mode project HCP-028C, Government of India for this work is gratefully acknowledged. Nishant Markandeya acknowledges the GATE fellowship provided by CSIR, Govt. of India New Delhi. The authors take the opportunity to thank to our research scholar Mr. Sachin Sonage and Mr. Rohit Shetty for their cooperation during the literature search and the analysis of data.

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[80] N. Gama, B. Godinho, G. Marques, R. Silva, A. Barros-Timmons, A. Ferreira, Recycling of polyurethane scraps via acidolysis, Chem. Eng. J. 395 (March) (2020), https://doi. org/10.1016/j.cej.2020.125102, 125102. [81] D. Marie, Consortium Creates Fluorescent Tech for Sorting Recyclables, 2020. https:// insights.globalspec.com/article/13335/consortium-creates-fluorescent-tech-forsorting-recyclables. (Accessed 1 October 2020). [82] C. Crockett, S. Sumar, The safe use of recycled and reused plastics in food contact materials—part II, Nutr. Food Sci. 96 (4) (1996) 34–37, https://doi.org/10.1108/ 00346659610119234. [83] Applied Nutrition, US Food and Food Safety, Recycled Plastics for Food-Contact Applications, 1995. [84] B. Raj, Recycling of plastics in food packaging, in: Plastics in Food packaging, Food Packaging Technology Department, Central Food Technological Research Institute, Mysore, India, 2020. http://icpe.in/Plastics%20in%20Food%20Packaging/pdf/14-Final.pmd. pdf. (Accessed 13 September 2020 (Chapter 14). [85] S.E. Selke, Recycling: Polymers, Encyclopedia of Materials: Science and Technology, 2001, pp. 8075–8079, https://doi.org/10.1016/b0-08-043152-6/01451-0. [86] NCL Innovations, Uses of Recycled PET, 2020. http://www.petrecycling.in/uses-ofrecycled-pet/. (Accessed 22 October 2020). [87] D.T. Sheppard, K. Jin, L.S. Hamachi, W. Dean, D.J. Fortman, C.J. Ellison, et al., Reprocessing postconsumer polyurethane foam using carbamate exchange catalysis and twinscrew extrusion, ACS Cent. Sci. 6 (6) (2020) 921–927, https://doi.org/10.1021/ acscentsci.0c00083. [88] Tranasparency Market Research, Recycled Plastic and Plastic Waste to Oil Market to Reach a Value of US$ 100 MN by 2027, 2020. https://www.transparencymarket research.com/pressrelease/recycled-plastics-plastic-waste-oil-market.htm#::text¼to %20Oil%20Market-,Recycled%20Plastic%20and%20Plastic%20Waste%20to%20Oil% 20Market%20to%20Reach,by%202027%3A%20Transparency%20Market%20Research& text¼The%20global%20recycled%20plasti. (Accessed 30 September 2020). [89] M. Biron, Recycling Plastics: Advantages and Limitations of Use, A Practical Guide to Plastics Sustainability, Elsevier, 2020, https://doi.org/10.1016/b978-0-12-8215395.00009-4. [90] Franklin Associates, New Study Confirms Recycling Plastics Significantly Reduces Energy Use and Greenhouse Gas Emissions, 2020. https://plastics.americanchemistry. com/Education-Resources/Publications/Life-Cycle-Inventory-of-PostconsumerHDPE-and-PET-Recycled-Resin.pdf. (Accessed 12 October 2020). [91] J. Hopewell, R. Dvorak, E. Kosior, Plastics recycling: challenges and opportunities, Philos. Trans. R. Soc. Lond. Ser. B Biol. Sci. (2009), https://doi.org/10.1098/rstb.2008.0311. [92] D. Version, Climate Benefits of Material Recycling Inventory of Average Greenhouse Gas Emissions for Denmark, Norway and Sweden, 2015, https://doi.org/10.6027/ TN2015-547. [93] Z. Cormier, Turning Carbon Emissions Into Plastic, 2020. https://www.bbcearth.com/ blog/?article¼turning-carbon-emissions-into-plastic. (Accessed 17 October 2020). [94] R.A. Sheldon, M. Norton, Green chemistry and the plastic pollution challenge: towards a circular economy, Green Chem. (2020), https://doi.org/10.1039/d0gc02630a.

Index Note: Page numbers followed by f indicate figures and t indicate tables.

A

environment and human health, effect of, 227–228 ethylene glycol, 70–71, 70f ethyl lactate, 79 farmers, direct benefits, 216–217 fertilizers, overuse of, 234 food crop agrowastes, 157–158 furan, 65, 65f 2,5-furandicarboxylic acid (FDCA), 75, 76f, 77t 2(5H) furanone, 65 furfural derived chemicals, 62, 63f lignocellulosic biomass, 62–64, 62t market size, 62 production of, 61, 61f furfuryl alcohol, 64, 64f furoic acid, 76 gamma-valerolactone (GVL), 71, 71f global agricultural production, 221–222 glycerin, 79–80, 79f greenhouse gas emissions, 222 groundnut residue, 200–201 horticultural crop agrowastes, 160 improper management, 222–223 India, agricultural sector in, 222–223 isoprene, 80 isosorbide, 72–73, 73f levulinic acid, 66–67, 66f, 67t ligno-cellulosic fibers, 234 maleic acid and maleic anhydride, 72, 72f management strategies, 222 open burning, 200–201 organic manure, 200–201 1,5-pentanediol, 74–75, 75f pharmaceutical chemicals, 169, 170t plantation crop agrowaste, 159–160 platform chemicals, 166–169, 166t, 167–168f 1,3-propane diol, 69–70, 70f p-xylene, 80–81, 80f

ACS. See Arsenic-containing sludge (ACS) Agricultural crop wastes acrylic acid, 73–74, 74f biochar production advantages, 200–201 applications, 214 choice, 200 from crop residue, 201–207 estimation method, 208–209 pyrolysis, 200 uses, 200 yield data, 211, 212t bio-oil, 215 biorefinery process biodiesel, 160–161 bioethanol, 161–163, 163f, 164t biogas, 164–165, 165f 1,3-butadiene, 78, 78f 1,4-butanediol, 78, 79f caprolactam, 67–68, 68f cash crop agrowastes, 159 categorization and sources agrochemical wastes, 227 animal waste, 223–224, 224f fisheries waste, 226–227 horticulture production waste, 226 meat and food processing waste, 224–225, 225f on-farm organic waste, 226 components, 222 crop residue annual production, 209 biochar production, 201–207 organic manure, 200–201 surplus, estimation of, 207–208 crop stalks and animal manure, 222 cyclopentanone, 68–69, 69f 2,5-diformyl furan (DFF), 76 2,5-dimethylfuran (DMF), 77–78, 77f environmental problems, 200–201

357

358

Index

Agricultural crop wastes (Continued) pyrolysis activity, 215–216 residues, 222 in rural households, 200–201 sources of, 57–58, 58f surplus dry biomass generation, 209–211, 210t sustainable development goals (SDGs), 222 technical description, 222 total area under cultivation, 211 toxins and breeding substrate, 222 value-added products, 158f, 170–171, 171f agrocement, 233–234 anaerobic digestion, 229–230 animal feed, 232 composting and vermicomposting, 230–231, 231f fertilizer, 229, 229f heavy metals, removal of, 231–232 pyrolysis and plasma gasification, 232–233, 233f Agricultural solid residue (ASR), 229–230 Agro industrial wastes, 14–18, 16–17f Alkali activated materials (AAMs), 13 Arsenic-containing sludge (ACS) arsenic removal, 136–138 leaching, 136–138 manganese dioxide-induced modification, 137 preparation with, 143 stabilization, 136–137 toxicity characteristics leaching procedure (TCLP), 136–137 utilization, 136–137 UV-Vis transmission spectra, 146, 148f x-ray diffraction profile, 146, 147f Artificial radiation, 28

B Bauxite residue. See Red mud Biochar production advantages, 200–201 applications, 214 choice, 200 from crop residue, 201–207 estimation method, 208–209 pyrolysis, 200 uses, 200 yield data, 211, 212t Biodiesel, 160–161 Bioethanol, 161–163, 163f, 164t

Biogas, 164–165, 165f Biomass agricultural crop wastes acrylic acid, 73–74, 74f 1,3-butadiene, 78, 78f 1,4-butanediol, 78, 79f caprolactam, 67–68, 68f constituents of, 58–59 crop types, 58–59 cyclopentanone, 68–69, 69f definition, 57–58 2,5-diformyl furan (DFF), 76 2,5-dimethylfuran (DMF), 77–78, 77f ethylene glycol, 70–71, 70f ethyl lactate, 79 furan, 65, 65f 2,5-furandicarboxylic acid (FDCA), 75, 76f, 77t 2(5H) furanone, 65 furfural, 61–64, 61f, 62t, 63f furfuryl alcohol, 64, 64f furoic acid, 76 gamma-valerolactone (GVL), 71, 71f glycerin, 79–80, 79f isoprene, 80 isosorbide, 72–73, 73f levulinic acid, 66–67, 66f, 67t maleic acid and maleic anhydride, 72, 72f 1,5-pentanediol, 74–75, 75f 1,3-propane diol, 69–70, 70f p-xylene, 80–81, 80f utilization of, 58–59 food crop, 57–58 lignocellulose biofuel, 61 constituents, 59, 60f gasification, 61 hydrolysis, 61 pre-treatment methods, 59 pyrolysis, 61 nonfood crop, 57–58 plant-based from the agricultural sector, 157 composition of, 156–157 feedstocks, 155–157 source, 155–156 Bio-oil, 215 Bioplastic, 349–350 Biorefinery process biodiesel, 160–161 bioethanol, 161–163, 163f, 164t

359

Index

biogas, 164–165, 165f Bioremediation, 19–21 Blast furnace slag (BFS) in cement and concrete, 10 chemical composition, 10 ferronickel slag (FNS), 11 glass/gravel like byproduct, 10 steel slag, 10 Brine sludge applications, 37–40, 40f caustic soda, 32–34, 33f challenges, 34–36 chemical properties, 34–36, 36f chlor-alkali industry, 32–34 chlorine, 34 compound annual growth rate (CAGR), 32–34 constituents, 34–36, 35f physical parameters, 34–36, 35t sludge waste, 34

C Carbon footprint, 348–349 Cash crop agrowastes, 159 Caustic soda, 32–34, 33f Central structure protein. See Fibroin Coal fly ash (FA). See Fly ash (FA) Cosmic radiation, 28

D Dairy wastes, 18 Depolymerization high density polyethylene (HDPE), 323 polycarbonate alcoholysis, 327–329, 328t catalytic depolymerization, 330 hydrolysis, 329–330 Resin Identification Codes (RIC), 326 polyethylene and polypropylene carbon nanotubes, 338 low density polyethylene (LDPE), 335–336 metallocene catalyst, 337 p-xylene, 336 solar thermal electrochemical process (STEP), 336 surfactants, 336–337 polyethylene terephthalate (PET) chemolysis, 321–323 glycolysis, 321 Resin Identification Codes (RIC), 320 polystyrene

expandable polystyrene (EPS), 326 heavy cycle oil (HCO), 324 light cycle oil (LCO), 324 thermal liquefaction, 325–326 polyvinyl chloride, 330–331 waste vehicle tire calcium carbide (CaC2) catalyst, 333 carbon black, 333 challenges, 331 heavy vehicle tire, 331–332 ketonization, 332 light vehicle tire, 331–332 medium vehicle tire, 331–332 petroleum ether, 333–334 reactors, 333 reclamation, 332 silica, 331 supercritical water, 333

E Electrodialysis, 126–127 Electronic waste (e-waste) cathode ray tubes (CRT), 139–140 co-doped blue color glass, 147–148, 148f foam glass, 148–149, 149f glass-to-glass recycling, 139–140 glass-to-lead recycling, 139–140 global generation, 138 indium tin oxide (ITO) film, 138–139 industrial solid wastes (ISW), 18–19 LCD monitors, 138–139 preparation with, 143, 144f printed circuit boards (PCBs), 139 pyrolysis, 139 raw materials, 138 recycling, 138–140

F FA. See Fly ash (FA) Ferronickel slag (FNS), 11 Fibroin compositions, 303, 303t properties, 304, 304f Fly ash (FA) adsorbent, 7 applications, 7, 8f, 37–40, 40f based geopolymer cement, 8–9, 9f bricks, 8 characterization, 5–7 chemical properties, 36f, 37 classification, 5 composition, 6, 7t

360

Index

Fly ash (FA) (Continued) in concretes, 7–8 fly waste, 37 geopolymer, 262–263 industrial waste acid rain, 240 as adsorbent, 249–250 in agriculture sector, 247 blended cements, 181–182 in bricks, 245–246, 246t C class, 242–244 cement production, 180 chemical constituents, 242–244, 244t in concrete industry, 182–183, 244–245 F class, 242–244 in flowable fills, 248 future perspectives, 250–251 generation, 239–240 grout material, 184 high-grade coal, 240 as light aggregates, 248 masonry bricks and blocks, 183 masonry mortar, 184 microconcrete and repair mortar, 184 in mosaic tiles, 247 as pesticide, 249 pollutant gases, 240 pozzolanic characteristics, 181 production and usage of, 240–242, 241t, 243t ready-mix plaster, 183 soil conditioner, 185 in stabilized base course, 247 state-wise data, 240, 241–242t tile adhesive material, 185 tile base material, 184 toxins, 240 wall panels, 183 key elements, 37 mass attenuation coefficient, 37, 38f physical parameters, 35t, 37 physical properties, 5, 5–6t in soils, 9 soil stabilizer, red mud, 48–49 water purification, 9–10 Foam glass, 142, 149f Food crop agrowastes, 157–158 Food waste apple manufacturing industries, 116 berries, 117 bioactive compounds, recovery of adsorption, 126

electrodialysis, 126–127 bioelectricity, 114 biohythane, 114 biomass, agricultural production, 116 broccoli, 118 calorific values, 114 citrus fruits, 117 consequences, 111–112 enzyme assisted extraction, 121 extrusion process, 119–120 food chain, degradation of, 112 food loss, 112 high hydrostatic pressure extraction, 123 mango seed kernel, 117 membrane assisted extraction, 123–125 microwave-assisted extraction, 122 nature and biological impact, 116 olive, 118 organic, 111–112 pineapple, 117 polyphenols anticarcinogenic activities, 113–114 antineoplastic drug action, 113–114 antioxidant activity, 113 bioavailability, 112–113 photochemical stabilization, 113 stability, 113 structural evidence, 113 therapeutic action, 112 potato, 118 potential applicability, 127–128 processing treatment, 115 production and consumption, 111 pulse electric field, 122–123 recovery process, 118–119 solvent extraction, 120 sub critical water extraction, 121 sustainable green fuels, 114 tea waste, 115–116 tomato, 118 types and bioactivity, 115, 115f ultrasound-assisted extraction, 121–122 Fossil fuels, 57–58

G Geopolymer acid resistance, 268 alkali resistance, 268 construction and demolition (C&D) wastes, 263–266, 264–265f dissolution, 261 fly ash (FA) utilization, 262–263

Index

industrial solid wastes (ISW), 259–261 kaolin utilization, 263 metakaolin utilization, 263 municipal solid waste (MSW), encapsulation of, 266 polycondensation, 261 precipitation, 261 rice husk ash (RHA), 263 structure, 261 terminology, 261 in thermal transportation, 268–269 thermoplastic polymers, recycling of, 266–267 wastepaper, cardboard, recycling of, 266 GFRP. See Glass fiber-reinforced polymer (GFRP) Glass arsenic-containing sludge (ACS) arsenic removal, 136–138 leaching, 136–138 manganese dioxide-induced modification, 137 preparation with, 143 stabilization, 136–137 toxicity characteristics leaching procedure (TCLP), 136–137 utilization, 136–137 UV-Vis transmission spectra, 146, 148f x-ray diffraction profile, 146, 147f chromium immobilization, 141–142 electronic waste (e-waste) cathode ray tubes (CRT), 139–140 co-doped blue color glass, 147–148, 148f foam glass, 148–149, 149f glass-to-glass recycling, 139–140 glass-to-lead recycling, 139–140 global generation of, 138 indium tin oxide (ITO) film, 138–139 LCD monitors, 138–139 preparation with, 143, 144f printed circuit boards (PCBs), 139 pyrolysis, 139 raw materials, 138 recycling, 138–140 foam glass, 142, 149f melting, 141 rice husk ash (RHA), 140–141, 144, 150f tannery solid waste (TSW) biosorbent, 135–136 chromium, 133–134 clay brick preparation, 135 fleshing, 134–135

361

leaching toxicity, 133–135 management, 134 methane yield, 134–135 polished glass block, 146, 146f in poultry feed, 133–134 preparation with, 142–143 pyrolysis and incineration, 134–135 red category, 133–134 toxic greenhouse gases emission, 133–134 transmission spectra, 146, 146f wastewater treatment process, 134–135 x-ray diffraction profile, 145–146, 145f waste incorporation, 141–142 Glass fiber-reinforced polymer (GFRP) composite materials pathways, 274, 274f incineration, 275–276 land filling, 274–275 recycling, 275–276 waste glass fiber (WGF) applications, 292 degradation enhancement, 279 degree of fractionation, 277–278 dough molding compound (DMC), 282–284 e-glass fibers, 276, 277t fluidized bed process, 281, 281f glass, definition of, 276 mechanical performance, 284 mechanical properties, 282, 283t microwave-assisted chemical oxidation method, 280–281 molten glass, 276 natural aggregates (NA), 285–286 polyester composites, 286–291, 286–291f, 287t printed circuit board (PCB), 284–285 pyrolysis, 280–281 recycled acrylonitrile butadiene styrene granules (RABS), 282, 282f short length fiber, 277, 278f thermally activated semiconductors, 279 thermolysis, 280–281 water-based solvolysis, 279 waste material, disposal of, 274 Glue protein. See Sericin Ground granulated blast furnace slag (GGBFS) blended cements, 181–182 cement production, 180 in concrete, 182–183 grout material, 184

362 Ground granulated blast furnace slag (GGBFS) (Continued) masonry bricks and blocks, 183 masonry mortar, 184 microconcrete and repair mortar, 184 pozzolanic characteristics, 181 ready-mix plaster, 183 soil conditioner, 185 tile adhesive material, 185 tile base material, 184 wall panels, 183

H Heat resource, 19, 20f Horticultural crop agrowastes, 160

I Industrial solid wastes (ISW) agro industrial wastes, 14–18, 16–17f bioremediation, 19–21 blast furnace slag (BFS) in cement and concrete, 10 chemical composition, 10 ferronickel slag (FNS), 11 glass/gravel like byproduct, 10 steel slag, 10 classification based on industrial process, 3–4, 4f industrial sectors, 3, 4f nature, 3, 4f per pollution characteristics, 3, 4f dairy wastes, 18 definition, 1 e-waste, 18–19 fly ash (FA) adsorbent, 7 applications, 7, 8f based geopolymer cement, 8–9, 9f bricks, 8 characterization, 5–7 classification, 5 composition, 6, 7t in concretes, 7–8 physical properties, 5, 5–6t in soils, 9 water purification, 9–10 as heat resource, 19, 20f plastic waste disposal, 14, 15f management, 13–14, 15f recycling, 13–14 thermoplastics, 13, 14f thermosets, 13

Index

reducing, reusing and recycling (3R) concept, 2, 2f rubber tires in concrete, 11–12 waste tires (WT), recycled/reused, 11, 12f silica fume (SF), 13 used glasses, 12–13 Industrial waste annual generation, 179 composite and biomaterials lab (CBML), 269 construction materials, 179 definition, 239–240, 255–256 fly ash (FA) acid rain, 240 as adsorbent, 249–250 in agriculture sector, 247 blended cements, 181–182 in bricks, 245–246, 246t C class, 242–244 cement production, 180 chemical constituents, 242–244, 244t in concrete industry, 182–183, 244–245 F class, 242–244 in flowable fills, 248 future perspectives, 250–251 generation of, 239–240 grout material, 184 high-grade coal, 240 as light aggregates, 248 masonry bricks and blocks, 183 masonry mortar, 184 microconcrete and repair mortar, 184 in mosaic tiles, 247 as pesticide, 249 pollutant gases, 240 pozzolanic characteristics, 181 production and usage, 240–242, 241t, 243t ready-mix plaster, 183 soil conditioner, 185 in stabilized base course, 247 state-wise data, 240, 241–242t tile adhesive material, 185 tile base material, 184 toxins, 240 wall panels, 183 geoenvironmental pollution, source of, 179 geopolymer acid resistance, 268

363

Index

alkali resistance, 268 construction and demolition (C&D) wastes, 263–266, 264–265f dissolution, 261 fly ash (FA) utilization, 262–263 kaolin utilization, 263 metakaolin utilization, 263 municipal solid waste (MSW), encapsulation of, 266 polycondensation, 261 precipitation, 261 rice husk ash (RHA), 263 structure, 261 terminology, 261 in thermal transportation, 268–269 thermoplastic polymers, recycling of, 266–267 wastepaper, cardboard, recycling of, 266 ground granulated blast furnace slag (GGBFS) blended cements, 181–182 cement production, 180 in concrete, 182–183 grout material, 184 masonry bricks and blocks, 183 masonry mortar, 184 microconcrete and repair mortar, 184 pozzolanic characteristics, 181 ready-mix plaster, 183 soil conditioner, 185 tile adhesive material, 185 tile base material, 184 wall panels, 183 industrialization, 239–240 landfill, 257 ordinary Portland cement (OPC)-based composites, 256–257 phosphogypsum global generation of, 185 plaster, 186 plaster boards, false ceiling, 187 statues and models, 187 wall panels, 186 wall putty, 186 plastic waste asphalt mix, 193–194 cement mortar and concrete, 194–195 pipes, 192–193 red mud in Bayer’s process, 187 brick manufacturing, 189

as catalyst, 190 cement mortar and concrete, 188 cement production, 188 ceramic products, 189–190 checkered tiles and paver blocks, 189 constituents of, 187 as filler in plastic, 191 geopolymers concrete, 189 wastewater treatment, 190 rice husk ash (RHA) adsorbents, 191 cement composites, 191 silicon-based materials, 191 waste management challenges to, 259 4R concept, 258–259 geopolymer, 259–261 in Indian cities, 257–258 methane gas, 258 principles of, 258–259 “Zero-Waste”, 256

L Lignocellulose biofuel, 61 constituents, 59, 60f gasification, 61 hydrolysis, 61 pre-treatment methods, 59 pyrolysis, 59

M Manufactured radiation. See Artificial radiation Membrane-based treatment, wastewater anisotropic membranes, 93 biological treatment, 92 chemical treatment, 92 enantiomeric separation, 92–93 feed solution, concentration of, 96–97 flow rate, 97–98 hybrid membrane, 95–96 membrane bioreactors, 96 membrane fouling, 96 nanocomposite membrane activated carbon, 99 adsorbents, 99 advanced oxidation process, 103 carbon nanotube (CNT), 99–101 chiral resolution techniques, 100 chitosan, 101 membrane bioreactors, 103

364 Membrane-based treatment, wastewater (Continued) membrane distillation, 103–104 recovery efficiency, 101–102, 102f wool scouring effluent, 103 per-vaporation, 95–96 physicochemical parameters, 93 pressure, 97 reverse osmosis membrane, 94–95 temperature, 97 Muga silk acid/alkali, effect of, 307 Antheraea assamensis, 295–296 antiquity, 297–298 art craft application, 313, 313f biodiesel applications, 314 biomaterial resource, 307–309 biomedical applications, 310 construction applications, 314 cosmetic application, 311–312, 312f cycles of, 302, 303f dietary application, 309–310, 309f distribution of, 298–300, 299–300f eco-friendly, 307 electricity conduction, 307 fibroin compositions, 303, 303t properties, 304, 304f Geographical Indication (GI) status, 300–301 heat conduction, 306 moisture absorbance, 306 “Muga Mission” project, 300–301 pharmaceutical application, 311 porosity, 307 production, 300–301, 301f properties, 307 scientific classification, 302, 302f sericin applications, 304–305 characteristics, 305, 306f compositions, 303, 303t properties, 305 “Silk Samagra” scheme, 300–301 structure, 305 tensile strength, 305–306 textile application, 312–313 tissue engineering, 310 Municipal solid waste (MSW) definition, 2, 255–256 encapsulation, 266 generation in, year 2018, 256–257, 257t

Index

N Nanocomposite membrane activated carbon, 99 adsorbents, 99 advanced oxidation process, 103 carbon nanotube (CNT), 99–101 chiral resolution techniques, 100 chitosan, 101 membrane bioreactors, 103 membrane distillation, 103–104 recovery efficiency, 101–102, 102f wool scouring effluent, 103 Natural radiation, 28 Neutron, 28–30, 29t Nontoxic radiation shielding materials advantages, 41 brine sludge applications, 37–40, 40f caustic soda, 32–34, 33f challenges, 34–36 chemical properties, 34–36, 36f chlor-alkali industry, 32–34 chlorine, 34 compound annual growth rate (CAGR), 32–34 constituents of, 34–36, 35f physical parameters, 34–36, 35t sludge waste, 34 fly ash (FA) applications, 37–40, 40f chemical properties, 36f, 37 fly waste, 37 key elements for, 37 mass attenuation coefficient, 37, 38f physical parameters, 35t, 37 gamma rays’ interaction, 30 healthcare applications, 41 industrial wastes, examples of, 42 lead, 30–31 panels, 31–32 paver blocks, 31–32 tiles, 31–32

P Petroleum resources, 155–156 Pharmaceutical industry chemicals, 169, 170t composition, 89–90, 90f wastewater anisotropic membranes, 93 anthropogenic heavy metals, 92 biodegradable behavior, 87–88

Index

biological treatment, 92 characteristics, 92 chemical treatment, 92 composition, 87–88 contaminants, 92 enantiomeric separation, 92–93 feed solution, concentration of, 96–97 fermentation process, 91 flow rate, 97–98 hybrid membrane, 95–96 hydrocarbon derivatives, 92 industrial effluent discharge, 87–88 membrane bioreactors, 96 membrane fouling, 96 minimization, 87 nanocomposite membrane, 99–105, 102f per-vaporation, 95–96 physicochemical parameters, 93 pressure, 97 reverse osmosis membrane, 94–95 source, 87–88 temperature, 97 transition metal contaminants, 87–88 water, use of, 87–88 Phosphogypsum global generation, 185 plaster, 186 plaster boards, false ceiling, 187 statues and models, 187 wall panels, 186 wall putty, 186 Plantation crop agrowaste, 159–160 Plant-based biomass from the agricultural sector, 157 composition of, 156–157 feedstocks, 155–157 Plasma gasification, 232–233 Plastic “Beat Plastic Pollution”, 317–318 Bureau of Indian Standards (BIS), 319 circular economy, 317–318, 339 hydrocarbon resource, 317–318 incineration, 317–318 landfills, dumped in, 317–318 non-biodegradable, 317–319 recycling chemical, 318 and CO2 emissions, 347–350, 348t, 349f depolymerization of high density polyethylene (HDPE), 323 depolymerization of polycarbonate, 326–330, 328t

365

depolymerization of polyethylene terephthalate (PET), 320–323 depolymerization of polystyrene, 324–326 green chemistry principles, 318 limitations, 350 mechanical, 318 mixture of waste polymers, 340–341, 340t, 342f polyamides, 334–335 polyethylene and polypropylene, 335–338, 338f polymers, 342–347 polyurethane (PU) foam, 338–340 polyvinyl chloride depolymerization, 330–331 primary, 318 secondary, 318 separation process, 320 tertiary, 318 thermal, 318 waste segregation pathway, 319–320 waste vehicle tire depolymerization, 331–334 Resin Identification Codes (RIC), 318–319, 319t 6 R’’s concept, 350–351 single-use nature, 317–318 thermoplastics, 318–319 waste disposal, 14, 15f management, 13–14, 15f recycling, 13–14 thermoplastics, 13, 14f thermosets, 13 Platform chemicals, 166–169, 166t, 167–168f Polyphenols anticarcinogenic activities, 113–114 antineoplastic drug action, 113–114 antioxidant activity, 113 bioavailability, 112–113 photochemical stabilization, 113 stability, 113 structural evidence, 113 therapeutic action, 112 Pozzolanic stabilized mixtures, 247 Pulverized fuel ash (PFA). See Fly ash (FA) Pyrolysis agricultural crop wastes, 215–216 biochar production, 200 electronic waste (e-waste), 139 lignocellulose, 61

366

Index

Pyrolysis (Continued) tannery solid waste (TSW), 134–135 value-added products, 232–233, 233f waste glass fiber (WGF), 280–281

R Radiation aerospace industry, 29–30, 29t artificial, 28 cosmic, 28 definition, 27–28 exposure to, 28 forms, 30 ionizing energy, 27–28 medical industry, 29–30, 29t natural, 28 neutron, 28 nonionizing energy, 27–28 nuclear reactors, 29–30, 29t penetration ability, 30–31, 31f photon attenuation coefficients, 28–29 radiotherapy, 28 role in, 28 shielding efficiency, 29–30 shielding material advantages, 41 brine sludge, 32–40, 33f, 35–36f, 35t, 38f, 40f fly ash (FA), 36f, 37–40, 38f, 40f gamma rays’ interaction, 30 healthcare applications, 41 industrial wastes, examples of, 42 lead, 30–31 panels, 31–32 paver blocks, 31–32 tiles, 31–32 Recycled polymers additives bitumen, 343–344 eucalyptus wood, 344 high density polyethylene (HDPE), 342–343 low-density polyethylene (LDPE), 342–343 nanomaterials, 342–343 plasticizer, 344 polyetherimide, 344 polystyrene (PS), 342–343 wood plastic composites (WPC), 343–344 in bottle manufacturing, 346, 347f chemical, 318

and CO2 emissions carbon footprint, 348–349 drop-in plastics, 349–350 energy recovery, 347–348, 348t incineration, 348–349, 349f new plastics, 349–350 polyamide recycling, 348–349 polyethylene terephthalate (PET), 348–349 polyurethane production, 349 virgin plastic production, 348–349, 349f depolymerization of high density polyethylene (HDPE), 323 depolymerization of polycarbonate alcoholysis, 327–329, 328t catalytic depolymerization, 330 hydrolysis, 329–330 Resin Identification Codes (RIC), 326 depolymerization of polyethylene terephthalate (PET) chemolysis, 321–323 glycolysis, 321 Resin Identification Codes (RIC), 320 depolymerization of polystyrene expandable polystyrene (EPS), 326 heavy cycle oil (HCO), 324 light cycle oil (LCO), 324 thermal liquefaction, 325–326 in food industry, 345–346 green chemistry principles, 318 limitations, 350 mechanical, 318 mixture of waste polymers catalyst composition, 341 with catalysts and additive, 340, 340t Chevron Philips Chemicals (CPChem), 341 optimized depolymerization methods, 341, 342f polyamides Nylon-6, 334–335 Nylon-66, 334 polyethylene and polypropylene carbon nanotubes, 338 low density polyethylene (LDPE), 335–336 metallocene catalyst, 337 p-xylene, 336 solar thermal electrochemical process (STEP), 336 surfactants, 336–337 polyurethane (PU) foam

Index

aminolysis and ammonolysis, 339–340 glycolysis and hydrolysis, 339 Resin Identification Codes (RIC), 338 synthesis of, 346–347 polyvinyl chloride depolymerization, 330–331 primary, 318 secondary, 318 separation process, 320 tertiary, 318 thermal, 318 waste segregation pathway, 319–320 waste vehicle tire depolymerization calcium carbide (CaC2) catalyst, 333 carbon black, 333 challenges, 331 heavy vehicle tire, 331–332 ketonization, 332 light vehicle tire, 331–332 medium vehicle tire, 331–332 petroleum ether, 333–334 reactors, 333 reclamation, 332 silica, 331 supercritical water, 333 Red mud applications, 46 in Bayer’s process, 45–46 byproduct, alumina extraction, 45–46 challenges, 45–46 characteristics, 45–46 chemical properties, 46, 46t global production, 45–46 industrial waste in Bayer’s process, 187 brick manufacturing, 189 as catalyst, 190 cement mortar and concrete, 188 cement production, 188 ceramic products, 189–190 checkered tiles and paver blocks, 189 constituents of, 187 as filler in plastic, 191 geopolymers concrete, 189 wastewater treatment, 190 physical properties, 47, 47t soil remediation, 46 soil stabilizer additives, 47–48 applications of, 49, 50f, 51–53t black cotton soil, 49 contaminated soil, 49–50

367

expansive soil, 49 fly ash (FA), 48–49 Hungarian red mud, 48–49 immobilizing agents, 48 maximum dry density (MDD), 49–50 principle, 47–48 utilization, 46 Reducing, reusing and recycling (3R) concept, 2, 2f Rice husk ash (RHA) geopolymer, 263 glass, 140–141, 144, 150f industrial waste adsorbents, 191 cement composites, 191 silicon-based materials, 191 Rubber tires in concrete, 11–12 waste tires (WT), recycled/reused, 11, 12f

S Sericin applications, 304–305 characteristics, 305, 306f compositions, 303, 303t properties, 305 subunits, 304–305 Shielding materials. See Nontoxic radiation shielding materials Silica fume (SF), 13 Silk Muga variety acid/alkali, effect of, 307 Antheraea assamensis, 295–296 antiquity of, 297–298 art craft application, 313, 313f biodiesel applications, 314 biomaterial resource, 307–309 biomedical applications, 310 construction applications, 314 cosmetic application, 311–312, 312f cycles, 302, 303f dietary application, 309–310, 309f distribution, 298–300, 299–300f eco-friendly, 307 electricity conduction, 307 fibroin, 303–304, 303t, 304f Geographical Indication (GI) status, 300–301 heat conduction, 306 moisture absorbance, 306 “Muga Mission” project, 300–301

368

Index

Silk (Continued) pharmaceutical application, 311 porosity, 307 production, 300–301, 301f properties, 307 scientific classification, 302, 302f sericin, 303–305, 303t, 306f “Silk Samagra” scheme, 300–301 structure, 305 tensile strength, 305–306 textile application, 312–313 tissue engineering, 310 mulberry silk, 296–297, 297f non-mulberry silk, 296–297, 297f origin, 296 role in, 295–296 sericulture, 295–296 Soil remediation, 46 Soil stabilizer additives, 47–48 applications, 49, 50f, 51–53t black cotton soil, 49 contaminated soil, 49–50 expansive soil, 49 fly ash (FA), 48 Hungarian red mud, 48–49 immobilizing agents, 48 maximum dry density (MDD), 49–50 principle, 47–48 Solid waste. See Waste Steel slag, 10

T Tannery solid waste (TSW) biosorbent, 135–136 chromium, 133–134 clay brick preparation, 135 fleshing, 134–135 leaching toxicity, 133–135 management, 134 methane yield, 134–135 polished glass block, 146, 146f in poultry feed, 133–134 preparation with, 142–143 pyrolysis and incineration, 134–135 red category, 133–134 toxic greenhouse gases emission, 133–134 transmission spectra, 146, 146f wastewater treatment process, 134–135 x-ray diffraction profile, 145–146, 145f Textile industry chemicals, 88 coloring and processing, 88

composition, 89–90, 90f diseases caused, 89 dye molecules chromophores and auxochromes, 89 effluent composition, 89–90 structural varieties, 89 synthetic, 89 water contamination, 90–91 ecological balance, disruption in, 89 liquid fractions, 89 membrane science, 90–91 pollution, 89 residual chlorine, 88–89 toxic metals, 88–89 wastewater anisotropic membranes, 93 anthropogenic heavy metals, 92 biological treatment, 92 characteristic, 92 chemical treatment, 92 contaminants, 92 enantiomeric separation, 92–93 feed solution, concentration of, 96–97 fiber production procedures, 91 flow rate, 97–98 hybrid membrane, 95–96 membrane bioreactors, 96 membrane fouling, 96 nanocomposite membrane, 99–105, 102f per-vaporation, 95–96 physicochemical parameters, 93 pressure, 97 reverse osmosis membrane, 94–95 temperature, 97 water absorption, 90–91 TSW. See Tannery solid waste (TSW)

V Value-added products acrylic acid, 73–74, 74f agricultural waste, 158f, 170–171, 171f agrocement, 233–234 anaerobic digestion, 229–230 animal feed, 232 composting and vermicomposting, 230–231, 231f fertilizer, 229, 229f heavy metals, removal of, 231–232 pyrolysis and plasma gasification, 232–233, 233f 1,3-butadiene, 78, 78f 1,4-butanediol, 78, 79f caprolactam, 67–68, 68f

Index

cyclopentanone, 68–69, 69f 2,5-diformyl furan (DFF), 76 2,5-dimethylfuran (DMF), 77–78, 77f ethylene glycol, 70–71, 70f ethyl lactate, 79 furan, 65, 65f 2,5-furandicarboxylic acid (FDCA), 75, 76f, 77t 2(5H) furanone, 65 furfural derived chemicals, 62, 63f lignocellulosic biomass, 62–64, 62t market size, 62 production of, 61, 61f furfuryl alcohol, 64, 64f furoic acid, 76 gamma-valerolactone (GVL), 71, 71f glycerin, 79–80, 79f isoprene, 80 isosorbide, 72–73, 73f levulinic acid, 66–67, 66f, 67t maleic acid and maleic anhydride, 72, 72f 1,5-pentanediol, 74–75, 75f phosphogypsum plaster, 186 plaster boards, false ceiling, 187 statues and models, 187 wall panels, 186 wall putty, 186 1,3-propane diol, 69–70, 70f p-xylene, 80–81, 80f

W Waste classification based on industrial process, 3–4, 4f industrial sectors, 3, 4f nature, 3, 4f per pollution characteristics, 3, 4f definition, 1, 255–256 end-of-life, 2 industrial waste (see Industrial waste) management, 2 challenges to, 259 4R concept, 258–259 geopolymer, 259–261 in Indian cities, 257–258 methane gas, 258 principles, 258–259 municipal solid waste (MSW), 255–256 reducing, reusing and recycling (3R) concept, 2, 2f

369

Waste glasses (WG), 12–13 Waste glass fiber (WGF) applications, 292 degradation enhancement, 279 degree of fractionation, 277–278 dough molding compound (DMC), 282–284 e-glass fibers, 276, 277t fluidized bed process, 281, 281f glass, definition of, 276 mechanical performance, 284 mechanical properties, 282, 283t microwave-assisted chemical oxidation method, 280–281 molten glass, 276 natural aggregates (NA), 285–286 polyester composites abrasive wear behavior, 290–291, 291f abrasive wear testing, 288–289, 288–289f operating parameters, 286–287 physical and mechanical properties, 287t specific wear rate (k0) vs. applied load, 286–287, 286f wear behavior, 289–290, 290f printed circuit board (PCB), 284–285 pyrolysis, 280–281 recycled acrylonitrile butadiene styrene granules (RABS), 282, 282f short length fiber, 277, 278f thermally activated semiconductors, 279 thermolysis, 280–281 water-based solvolysis, 279 Waste incorporation, glass arsenic-containing sludge (ACS) arsenic removal, 136–138 leaching, 136–138 manganese dioxide-induced modification, 137 preparation with, 143 stabilization, 136–137 toxicity characteristics leaching procedure (TCLP), 136–137 utilization, 136–137 UV-Vis transmission spectra, 146, 148f x-ray diffraction profile, 146, 147f chromium immobilization, 141–142 electronic waste (e-waste) cathode ray tubes (CRT), 139–140 co-doped blue color glass, 147–148, 148f foam glass, 148–149, 149f glass-to-glass recycling, 139–140 glass-to-lead recycling, 139–140

370

Index

Waste incorporation, glass (Continued) global generation, 138 indium tin oxide (ITO) film, 138–139 LCD monitors, 138–139 preparation with, 143, 144f printed circuit boards (PCBs), 139 pyrolysis, 139 raw materials for, 138 recycling, 138–140 foam glass, 142, 149f melting, 141 rice husk ash (RHA), 140–141, 144, 150f tannery solid waste (TSW) biosorbent, 135–136 chromium, 133–134 clay brick preparation, 135 fleshing, 134–135 leaching toxicity, 133–135 management, 134 methane yield, 134–135 polished glass block, 146, 146f in poultry feed, 133–134 preparation with, 142–143 pyrolysis and incineration, 134–135 red category, 133–134 toxic greenhouse gases emission, 133–134 transmission spectra, 146, 146f wastewater treatment process, 134–135 x-ray diffraction profile, 145–146, 145f waste incorporation, 141–142 Wastewater generation, 91–92 Wastewater treatment anisotropic membranes, 93 anthropogenic heavy metals, 92

biodegradable behavior, 87–88 biological treatment, 92 characteristics, 92 chemical treatment, 92 composition, 87–88 contaminants, 92 enantiomeric separation, 92–93 feed solution, concentration of, 96–97 fermentation process, 91 fiber production procedures, 91 flow rate, 97–98 hybrid membrane, 95–96 hydrocarbon derivatives, 92 industrial effluent discharge, 87–88 membrane bioreactors, 96 membrane fouling, 96 minimization, 87 nanocomposite membrane activated carbon, 99 adsorbents, 99 advanced oxidation process, 103 carbon nanotube (CNT), 99–101 chiral resolution techniques, 100 chitosan, 101 membrane bioreactors, 103 membrane distillation, 103–104 per-vaporation, 95–96 physicochemical parameters, 93 pressure, 97 reverse osmosis membrane, 94–95 source, 87–88 temperature, 97 transition metal contaminants, 87–88 WGF. See Waste glass fiber (WGF)