Bio-Inspired Nanotechnology 9815080180, 9789815080186

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Bio-Inspired Nanotechnology Edited by Kaushik Pal

University Centre for Research and Development (UCRD) Chandigarh University Gharuan, Mohali Punjab, India

& Nidhi Asthana

Department of Physics Babasaheb Bhimrao Ambedkar University Lucknow, U.P., India

Bio-Inspired Nanotechnology Editors: Kaushik Pal and Nidhi Asthana ISBN (Online): 978-981-5080-17-9 ISBN (Print): 978-981-5080-18-6 ISBN (Paperback): 978-981-5080-19-3 © 2023, Bentham Books imprint. Published by Bentham Science Publishers Pte. Ltd. Singapore. All Rights Reserved. First published in 2023.

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CONTENTS PREFACE ................................................................................................................................................ i LIST OF CONTRIBUTORS .................................................................................................................. iv CHAPTER 1 DESIGN AND CHARACTERIZATION OF SMART SUPRAMOLECULAR NANOMATERIALS AND THEIR BIOHYBRIDS ............................................................................. Jyothy G. Vijayan INTRODUCTION .......................................................................................................................... SUPRAMOLECULAR NANOPARTICLES (SNPS) ................................................................. Hybrid Supramolecular Nanostructures .................................................................................. STACKING OF SNPS .................................................................................................................... DESIGN AND SYNTHESIS OF SUPRAMOLECULAR BIOHYBRID MATERIALS ......... DESIGN OF SNPS AS SENSORS AND DRUG DELIVERY SYSTEM .................................. Bioconjugation of SNP System over Metallic Surfaces ........................................................ Nanoaggregation as Signal Transducers ................................................................................. DESIGN OF SUPRAMOLECULAR POLYMERIC NANOPARTICLES .............................. ADVANTAGES OF SUPRAMOLECULAR BIOHYBRID MATERIALS ............................. Modularity ............................................................................................................................... Dynamic Reciprocity .............................................................................................................. Biomimicry ............................................................................................................................. CHARACTERIZATION TECHNIQUES USED IN SUPRAMOLECULAR CHEMISTRY Small and Wide Angle X-ray Scattering (Saxs and Waxs) .................................................... Dynamic and Static Light Scattering (DLS and SLS) ............................................................ Calorimetry ............................................................................................................................. Fourier Transform Spectroscopy FT-IR ................................................................................. Ultra Violet-visible Light Absorption Spectroscopy .............................................................. Fluorescence Spectroscopy ..................................................................................................... Nuclear Magnetic Resonance Spectroscopy ........................................................................... Scanning Electron Microscopy ............................................................................................... Transmission Electron Microscopy ........................................................................................ Atomic Force Microscopy ...................................................................................................... APPLICATIONS OF SUPRAMOLECULAR BIOHYBRID NANOMATERIALS ............... Drug Delivery ......................................................................................................................... Regenerative Medicine ........................................................................................................... Immuno Engineering .............................................................................................................. CONCLUSION AND FUTURE ASPECTS ................................................................................. ABBREVIATIONS ......................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ............................................................................................................................... CHAPTER 2 BIOCOMPATIBLE COMPOSITES AND APPLICATIONS .................................. Madhuri Lakhane and Megha Mahabole INTRODUCTION .......................................................................................................................... MATERIALS AND METHODS ................................................................................................... Materials ................................................................................................................................. Modification of ZSM-5 Zeolite .............................................................................................. Preparation of Zeolite/CNF Nanocomposite Films ................................................................ Characterization of Nanocomposite Films .............................................................................. Batch Dye Adsorption Studies ................................................................................................

1 2 2 3 3 3 4 4 4 4 6 6 6 6 7 7 7 7 8 8 8 8 8 9 9 9 9 9 10 10 11 11 11 11 11 16 16 19 19 19 20 20 21

RESULTS AND DISCUSSION ..................................................................................................... Nanocomposite Characterization ............................................................................................ FTIR Analysis ................................................................................................................ Dye Adsorption Analysis: Adsorption Equilibrium and Kinetic ............................................ Adsorption Kinetics ....................................................................................................... Adsorption Mechanism .................................................................................................. CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENT ............................................................................................................. REFERENCES ............................................................................................................................... CHAPTER 3 POLYMER NANOCOMPOSITE TECHNOLOGIES DESIGNED FOR BIOMEDICAL APPLICATIONS ......................................................................................................... Praseetha P. Nair INTRODUCTION .......................................................................................................................... Polymer Nanocomposites ....................................................................................................... BIOMEDICAL APPLICATIONS POLYMER NANOCOMPOSITES .................................... Bio-based Polymer Nanocomposites ...................................................................................... Carbon-based Polymer Nanocomposites ................................................................................ MOF/Polymer Nanocomposites .............................................................................................. Smart Polymers ....................................................................................................................... CONCLUSION AND FUTURE PERSPECTIVES ..................................................................... REFERENCES ............................................................................................................................... CHAPTER 4 NOVEL POLYMER NANOCOMPOSITES: SYNTHESIS, DESIGNING AND COST-EFFECTIVE BIOMEDICAL APPLICATIONS ..................................................................... A. P. Meera, Reshma R. Pillai and P. B. Sreelekshmi INTRODUCTION .......................................................................................................................... CELLULOSE BASED POLYMERS ............................................................................................ CHITOSAN-BASED POLYMER ................................................................................................. OTHER BIOPOLYMERS ............................................................................................................. METAL AND METAL OXIDE NANOPARTICLES ................................................................. CARBON-BASED NANOSTRUCTURES ................................................................................... POLYMER-BASED NANOPARTICLES .................................................................................... POLYMER NANOCOMPOSITES .............................................................................................. CONCLUSION AND FUTURE OUTLOOK .............................................................................. CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENT ............................................................................................................. REFERENCES ............................................................................................................................... CHAPTER 5 AN EMERGING AVENUE OF NANOMATERIALS MANUFACTURING AND PROSPECTIVES .................................................................................................................................... Binita Dutta INTRODUCTION .......................................................................................................................... NANOMATERIALS AND NANOTECHNOLOGY ................................................................... METHODS OF NANOPARTICLE SYNTHESIS ...................................................................... Physical Method ...................................................................................................................... Chemical Method .................................................................................................................... Biogenic Synthesis: The Green Alternative ............................................................................ NANOMATERIALS FOR EMERGING TECHNOLOGIES ....................................................

22 22 22 28 31 36 37 37 37 37 37 41 41 42 44 46 47 48 50 52 53 56 56 59 60 62 62 63 64 64 67 67 68 68 68 73 73 74 79 80 82 85 87

Nanomaterials for Food Industry ............................................................................................ Nanomaterials in Food Processing ............................................................................... Nanomaterials in Food Packaging ............................................................................... Nanomaterials for Agricultural Science .................................................................................. Nanomaterials in Medicine ..................................................................................................... Nanomaterials for Power Sector ............................................................................................. In Harvesting Energy .................................................................................................... In Energy Storage and Distribution .............................................................................. NANOTOXICOLOGY AND RELATED RISK MANAGEMENT ........................................... CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ...............................................................................................................................

87 88 89 90 92 93 94 96 98 101 101 102 102 102

CHAPTER 6 CURRENT RESEARCH TRENDS OF GRAPHENE NANOTECHNOLOGY ..... Monika Trivedi and Vasundhara Magroliya INTRODUCTION .......................................................................................................................... STATUS OF GRAPHENE IN NANOTECHNOLOGY ............................................................. SYNTHESIS AND PROPERTIES OF MATERIALS BASED ON GRAPHENE ................... Graphene Synthesis ................................................................................................................. Properties of Graphene ........................................................................................................... Electric Properties ........................................................................................................ Thermal Properties ....................................................................................................... Mechanical Strength ..................................................................................................... Chemical Properties ...................................................................................................... Optical Properties ......................................................................................................... Electrical Properties ..................................................................................................... Functionalization of Graphene ..................................................................................... APPLICATION OF GRAPHENE ................................................................................................ Composite Materials ............................................................................................................... Conductive Polymers .............................................................................................................. Electrochemical Sensors ......................................................................................................... Devices for Power Storage or Transformation ....................................................................... Supercapacitors ....................................................................................................................... Water Purification ................................................................................................................... CONCLUSION AND FUTURE OPPORTUNITIES .................................................................. CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENT ............................................................................................................. REFERENCES ...............................................................................................................................

106

CHAPTER 7 NANOMEDICINE TECHNOLOGY TRENDS IN PHARMACOLOGY ............... B. M. Reddy INTRODUCTION .......................................................................................................................... NANOMATERIALS AND NANODEVICES .............................................................................. Nanotechnology - History ....................................................................................................... Classification of Nanomaterials .............................................................................................. Liposomes ...................................................................................................................... Dendrimers .................................................................................................................... Metallic Nanoparticles .................................................................................................. Carbon Nanotubes ........................................................................................................

107 107 108 108 109 110 110 110 111 112 112 113 113 114 114 115 115 115 115 116 117 117 117 117 124 124 126 126 128 129 129 129 130

Quantum Dots ............................................................................................................... Synthesis of Nanomaterials ..................................................................................................... Top-down Approach ...................................................................................................... Bottom-up Approach ..................................................................................................... Characterization of Nanomaterials ......................................................................................... NANOTECHNOLOGY IN MEDICINE ...................................................................................... Antibacterial Properties of Nanomaterials .............................................................................. Medical Imaging and Diagnosis ............................................................................................. Drug and Bimolecular Delivery .............................................................................................. Therapeutics Treatment .......................................................................................................... Tissue Engineering .................................................................................................................. COMMERCIAL NANOMEDICINE ............................................................................................ Industrial Production ............................................................................................................... Benefits and Limitations ......................................................................................................... Potential Risks and Challenges ............................................................................................... CONCLUSION AND FUTURE PERSPECTIVE ....................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ............................................................................................................................... CHAPTER 8 AGRICULTURAL NANOTECHNOLOGIES: FUTURE PERSPECTIVES OF BIO-INSPIRED MATERIALS .............................................................................................................. Suma Sarojini, Shon George Shiju, Tanishka Dasgupta, Deepu Joy Parayil and Bhoomika Prakash Poornamath INTRODUCTION .......................................................................................................................... NANOMATERIALS TO IMPROVE PLANT GROWTH ......................................................... Nanomaterials in Fertilizer Formulation ................................................................................. Delivery of Nano Fertilizers ................................................................................................... NANOPESTICIDES ....................................................................................................................... Production of Nanopesticides (NPe) ....................................................................................... Types of Nanopesticides ......................................................................................................... Nano Fungicides ........................................................................................................... Nano Herbicides ............................................................................................................ NANOBIOSENSORS ..................................................................................................................... Need for Nanobiosensors ........................................................................................................ Nanobiosensors in Plant Disease Management ...................................................................... Nanobiosensors in Soil and Climate Analysis ........................................................................ NANOMATERIALS IN PLANT GENETIC ENGINEERING ................................................. PLANT NANOBIONICS ............................................................................................................... CONCLUSION AND FUTURE OUTLOOK .............................................................................. CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENT ............................................................................................................. REFERENCES ............................................................................................................................... CHAPTER 9 RECENT DEVELOPMENTS OF GRAPHENE-BASED NANOTECHNOLOGY TOWARDS ENERGY AND ENVIRONMENT ................................................................................... Swarna P. Mantry, Subhendu Chakroborty and M. V. B. Unnamatla INTRODUCTION .......................................................................................................................... GRAPHENE .................................................................................................................................... Family of Graphene ................................................................................................................

130 130 130 131 131 132 132 132 133 133 134 134 134 136 136 137 137 137 137 138 142 142 143 143 144 145 145 146 147 148 148 148 149 152 153 154 155 155 155 155 155 163 164 164 165

Graphene Oxide (GO) ................................................................................................... Reduced Graphene Oxide (rGO) .................................................................................. Doped GO ..................................................................................................................... ROLE AND APPLICATION OF GRAPHENE IN RENEWABLE ENERGY SYSTEMS .... Fuel Cell .................................................................................................................................. Graphene-based Electrocatalyst ................................................................................... Lithium-ion Battery (LIB) ...................................................................................................... Graphene-based Electrodes .......................................................................................... ROLE AND APPLICATION OF GRAPHENE IN ENVIRONMENT-RELATED ISSUES Graphene Nanotechnology in Water Treatment ..................................................................... Graphene Nanotechnology in Air Pollution Remediation ...................................................... CONCLUSION AND FUTURE PERSPECTIVE ....................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ...............................................................................................................................

165 165 165 166 166 167 168 170 170 171 173 175 176 176 176 176

SUBJECT INDEX .................................................................................................................................... 

i

PREFACE The book ‘Bio-inspired Nanotechnology’, exploring recent breakthroughs of exciting novelties finding inter-and cross-multidisciplinary sciences is based on micro- to nanofabrication of bio-engineered nanomaterials, spectroscopic characterization, and promising avenues of eco-friendly products as well as sustainable potential applications at the industrial scale. This book comprises of nine significant chapters written in diverse fields of study on green chemistry, nanotechnology, advanced materials, nano-biotechnology as well as next-generation biomedical technology. For the last several decades, there have been many projections on the future depletion of selfassembly of structural proteins that produce complex, hierarchical materials that exhibit a unique combination of mechanical, chemical, and transport properties. This controlled process covers dimensions ranging from the nano- to the macroscale. Such materials are desirable to synthesize integrated and adaptive materials and systems development of renewable energy technologies. On a different frontier, the growth and manipulation of materials on the nanometer scale have progressed at a fast pace. Selected recent and significant advances in the development of nanomaterials applications are reviewed in the entire book, and special emphasis is given to the investigations in Chapter 1 emphasizing an overview of supramolecular systems that are utilized as an effective technique in nanomanufacturing which enhances solubility, modification of surface properties, bioconjugation of nanoparticles fabrication which is the study of variations in non-covalent interaction to generate a nanostructural system with controlled characteristics. Chapter 2 deals with the significant fabrication of novel bio-nanocomposites by simple, cost-effective pathways using biocompatible, environmentally friendly zeolite and cellulose. The nanocomposites are water stable and have increased efficiency for adsorption. Moreover, these nanocomposites are more suitable for both Anionic and Cationic dyes. Chapter 3 illustrates polymer nanocomposites which are excellent materials with superior and exotic properties for biomedical applications. This chapter gives an overview of the major polymerbased composites reinforced with nanomaterials, their characteristics, fabrication techniques, and suitability in the biomedical field. The chapter gives an idea about research gaps in the material design and development, drawbacks, and challenges in in-vivo biomedical applications beneficial to researchers by giving an insight into novel materials suitable for further utilization in the biomedical era. Chapter 4 focuses on the conventional strategies based on nanotechnology which are being adopted in the biomedical field but having several disadvantages like severe side effects, toxicity, etc. From a future perspective, polymer nanocomposites have great potential in biomedical fields like tissue engineering, bone replacement or repair, dental applications and controlled drug delivery. The potential of biodegradable polymers in such applications is still under investigation. In the current scenario, polymer nanocomposites offer the combined merits of nanotechnology and the pros of biocompatibility and biodegradability to achieve the desired objective in biomedical applications. Chapter 5 illustrates modern-day nanomaterials of various kinds and morphologies and diverse methods of synthesizing them under top-down and bottom-up approaches are also discussed. Contributions of nanomaterials in some emerging technologies and industry sectors like the food industry, agricultural science, medicinal science and the power sector have been discussed. The need for awareness and risk management to combat the health impact of ‘nanotoxicity’ arising due to the rapid commercialization of nanomaterials is also mentioned. Also, Chapter 6 discusses the current discoveries in graphene-based materials in a variety of sectors as well as nanotechnology due to its hexagonal lattice and carbon atom arrangement. While, graphene nanosheets are excellent for usage as a 2D endorsement for applications of other nano-objects. Graphene-based

ii

nanocomposites are getting prominence in environmental and energy concerns in a variety of sectors. Chapter 7 deals with applications of nanotechnology in medicine which is relatively new, yet having a profound worldwide impact on biomedical research and public health. Nanomaterials possess several attractive features that permit them to perform physiological tasks such as multicolor imaging, identification of medical disorders, early diagnosis of diseases, delivery of therapeutics to target-specific organs, effective treatment of infections, increased bioavailability of drugs, and decreased side effects. Nanomedicine offers enormous opportunities in the near future and global efforts are underway to develop advanced smart nanomedical systems. Chapter 8 presents in-depth studies on the agricultural domain with which human civilization started and will carry on for survival. Since the growing population demands more resources from lesser area and time, bioinspired nanotechnology interventions like nanocarriers for fertilizer and pesticide delivery, soil and climate sensors and plant nanobionics to detect pollutants are the need of the hour. The strategies also have to be sustainable, in line with the UN SDGs as recalcitrant compounds have already posed significant damage to our planet. However, Chapter 9 explores the scenario of the utility of graphene nanotechnology that could be easily understood by its wide range of applications starting from energy storage devices to biomedical devices. Not only these, but graphene technology also provides purified water and air owing to its excellent physical, chemical, and mechanical properties. However, like any other technology, graphene nanotechnology has its limitations; advanced research is going on to overcome this. In the future, multifunctional graphene-based nanostructures with affordable cost will reach out to the common people. Remarkable strategies to employ assemblies of metal nanoparticles, organic-inorganic hybrid composite matrix, and carbon nanostructures in bioengineering conversion schemes are also illustrated in this book. Thus, it may be clear to all readers that nanotechnology-enabled bio-inspired nanotechnologies are starting to scale up dramatically. As they become mature and costeffective in the decades to come, biomaterials could eventually replace the traditional, environmental-unfriendly, fossils and improve the performance of the biomedical industry through the utilization of nanocatalysts in manufacturing materials with high durability. This book provides an overview of key current developments that direct future research attempts toward the utilization of such tailored nanostructures or hybrid nano assemblies will play an essential role in achieving the desired goal of cheap and efficient production. The book contains information with evidence from academicians, scientists, scholars, and engineers. It illustrates the wide-ranging interest in these areas and provides a background to the chapters, which address the novel synthesis of high-yield nanomaterials and their biomaterials, graphene, polymeric nanomaterials, green nanomaterials, green polyester, nanobiotechnology, interesting response characteristics of exclusive spectroscopic investigation as well as extensive electron microscopic study, health care, environmental and plant biology, social, ethical, and regulatory implications of various aspects of green nanotechnologies based leading functional nanomaterials. Liable appropriate regulation alongside the topics indicates that the commercial production of manufactured novel composite materials can be realized. Furthermore, many brilliant discoveries and explorations are highlighted in the entire book that can modulate spectroscopic performances with technical excellence in the inter-and cross-multidisciplinary research of high competence.

iii

Lastly, I would like to express my overwhelming gratitude to all the authors/co-editor for their excellent research contributions as well as peer-review, editing throughout this book. I would like to thank the entire team of Bentham Science Publishers for their efficient handling of this book at all harder stages of its publication. I am pretty sure and confident too that within a short interval, the book will be more popular in worldwide universities/institutes libraries and hopefully will achieve the highest citation in the coming years.

Kaushik Pal University Centre for Research and Development (UCRD) Chandigarh University Gharuan, Mohali Punjab, India & Nidhi Asthana Department of Physics Babasaheb Bhimrao Ambedkar University Lucknow, U.P., India

iv

List of Contributors A. P. Meera

Department of Chemistry, K.S.M. Sasthamcotta, Kollam, Kerala, India

Devaswom

Binita Dutta

Department of Chemistry, Banwarilal Bhalotia College, Asansol, West Bengal, India

B. M. Reddy

Abinnovus Consulting Pvt. Ltd., Technology Business Incubator (TBI), University of Madras, Guindy Campus, Chennai, Tamil Nadu, India

Bhoomika Prakash Poornamath

Department of Life Sciences, CHRIST (Deemed to be University), Bangalore, India

Deepu Joy Parayil

Department of Life Sciences, CHRIST (Deemed to be University), Bangalore, India

Jyothy G. Vijayan

Department of Chemistry, M.S. Ramaiah University of Applied Sciences, Bengaluru, India

Madhuri Lakhane

Dnynopasak College, Parbhani, India Swami Ramanand Teerth Marathwada University, School of Physical Sciences, Nanded, India

Monika Trivedi

School of Engineering, MIT-ADT University, Pune Maharashtra, India

Megha Mahabole

Swami Ramanand Teerth Marathwada University, School of Physical Sciences, Nanded, India

M. V. B. Unnamatla

Universidad Autonoma del Estado de Mexio, Toluca de Lerdo, Mexico

Praseetha P. Nair

Department of Chemical Engineering, Government Engineering College, Thrissur, Kerala, India

Reshma R. Pillai

Department of Chemistry, K.S.M. Sasthamcotta, Kollam, Kerala, India

Suma Sarojini

Department of Life Sciences, CHRIST (Deemed to be University), Bangalore, India

Shon George Shiju

Department of Life Sciences, CHRIST (Deemed to be University), Bangalore, India

Swarna P. Mantry

Department of Chemistry, Ravenshaw University, Cuttack, Odisha 753003, India

P. B. Sreelekshmi

Department of Chemistry, K.S.M. Sasthamcotta, Kollam, Kerala, India

Subhendu Chakroborty

IES University, Bhopal, Madhya Pradesh- 462044, India

Tanishka Dasgupta

Department of Life Sciences, CHRIST (Deemed to be University), Bangalore, India

Vasundhara Magroliya

Department of Science, Jayoti Vidyapeeth Women’s University, Jaipur, India

Devaswom

Devaswom

Board

Board

Board

College,

College,

College,

Bio-Inspired Nanotechnology, 2023, 1-15

1

CHAPTER 1

Design and Characterization Supramolecular Nanomaterials Biohybrids

of and

Smart their

Jyothy G. Vijayan1,* 1

Department of Chemistry, M.S. Ramaiah University of Applied Sciences, Bengaluru, India Abstract: Over the past few years, much effort has been taken to explore the applications of nanoparticle-based structures in different fields such as nanomedicine, molecular imaging, etc.. Supramolecular analytical methods have attracted researchers due to their chemical formula, flexibility, convenience, and modularity for the synthesis of nanoparticles. The incorporation of functional ligands on the surface of supramolecular nanoparticles helps to improve their performance in many areas. Fabrication of supra molecular materials with uniform size gives more advantages of using them in different fields. Characterization techniques like positron emission tomography imaging (PET), magnetic resonance imaging (MRI), fluorescence studies, scanning electron microscopy (SEM), and UV-Vis studies help to identify the molecular images and structure effectively. Supramolecular systems are used as an effective technique in the nano-design of supramolecular nano-systems. They enhance the solubility, modification of surface properties, bioconjugation of nanoparticles due to the supramolecular recognition properties, and supramolecular materials that are applied for the removal of targeted molecules. The designing process makes it able to function in complex matrices. This chapter discusses the design, synthesis and characterization of supramolecular nanostructures and their hybrids and also discusses their application in different fields.

Keywords: Characterization techniques, Complex matrices, Emulsion, Fluorescence studies, FT-IR studies, Functionalized nanomaterials, Hybrid nanoparticles, Ligands, Magnetic resonance imaging (MRI), Modularity, Nano precipitation nano structure, Nanoaggregation, Non-covalent interaction, Positron emission tomography imaging (PET), Scanning electron microscopy (SEM), Selfassembly, Stacking, Supramolecular nanostructure and UV-Vis studies. Corresponding author Jyothy G. Vijayan: Department of Chemistry, M.S. Ramaiah University of Applied Sciences, Bengaluru, India; Email: [email protected]

*

Kaushik Pal & Nidhi Asthana (Eds.) All rights reserved-© 2023 Bentham Science Publishers

2 Bio-Inspired Nanotechnology

Jyothy G. Vijayan

INTRODUCTION Supramolecular chemistry is identified as the study of the chemistry of noncovalent interactions. Weak and strong interactions are used to form nanoassemblies and novel nanomaterials. These forms are applied in different fields such as biomedical, pharmaceutical and analytical. Supramolecular chemistry is the branch where studies emulated from nature are considered. Supramolecular chemistry is explored as the chemistry beyond the molecule. It is more studied due to the efficiency of the molecule to design the self-assembled systems. Generally, supramolecular complexes are highly dynamic with their complementary guest molecules [1]. They perform various weak and reversible non-covalent interactions such as ion-ion, pi-pi, hydrogen bonding, weak van der Waals interactions, etc.. [2]. Supramolecular systems are efficient due to their inherent modularity, assembling-dissembling to external stimuli and their reversible nature. Supramolecular chemistry is mainly based on the concept of self-assembly and molecular recognition [3]. This review details about the application of supramolecular systems, design, synthesis and characterization of supramolecular nanoparticles and application of SNP and its hybrids in different areas. SUPRAMOLECULAR NANOPARTICLES (SNPS) They are mainly classified into organic supramolecular nanoparticles and inorganic supramolecular nanoparticles. Supramolecular identification of nanoparticles can generate stable and packed 3D functional nanostructures. βcyclodextrin (CD) acts in organic supramolecular nanoparticles as a natural host for guest organic molecules (ferrocene). It helps to form specific kinetically labile inclusion complexes. These guest-host complexes were applied in supra molecular system to assist the nanoparticle’s assembly. The guest or host molecule was attached to the surface of different nanoparticles such as silica, gold, polystyrene, etc.. The major strength in supramolecular chemistry is the fine-tuning and binding strength of the related supra molecules. The reversible bonding of the nanostructure from the surface is very important for designing novel nanoarchitectures. It is gained by the assembly of supramolecular nanoparticles. SNPs are prepared from the mix of supra and polymer chemistry, and their interactions. While synthesizing drug delivery system, we first need to design biodegradable SNPs. It is recommended to use the combination of polymer and supramolecular chemistry which can be added with organic and inorganic NPs [4]. They help to tune the flexibility of polymer chains. In this way, they enable to design and synthesize different types of NPs. They are applicable in nanoimaging, nanomedicine, bioanalytical chemistry, etc.. These materials are

Smart Supramolecular Nanomaterials

Bio-Inspired Nanotechnology 3

biodegradable and biocompatible. SNPs are able to tune and optimize themselves for their targeted applications [5]. In SNP formations, the reactant biodegradable NPs are made up of monomers such as PLA, PA and copolymers. Many studies have reported the application of biodegradable SNPs for drug delivery. These SNPs are applicable in making stimuli-responsive multifunctional nanodevices [6]. As a result, polymer chains provide flexible branches which are functionally modified with macrocycles and connected by non-covalent interactions. They finally form polymeric supramolecular NPs that have wide applications in the pharmaceutical industry. Hybrid Supramolecular Nanostructures Biobased hybrid supramolecular nanostructures of inorganic and organic molecules have enough potential for the improvement of properties in electronic and energy transduction. They are highly applicable in the synthesis of nanomedicines and nanosensors [7] based fields. Nanoparticles used to synthesize hybrid supramolecular materials have vast functionalities on their nanostructure such as fluorescent, magnetic, metallic, drug-loaded, bioconjugates, etc.. [8]. Addition of metallic NPs into the polymeric NPs and supramolecular NPs makes them more efficient. It helps to enhance the intrinsic properties of each component which will tune the design and flexibility of the required nanoarchitecture . STACKING OF SNPS Generally, the assembly of molecules into 1D supramolecular polymer system leads to the formation of double sided motifs. These motifs are efficient in facial association and stacking through the combination of various non-covalent interactions. The assembly of these small molecular stacking motifs is led by their molecular structure and architecture. These assemblies can be varied by different factors such as pH, solvent polarity, salt concentration, etc. [9]. But some molecular stacking motifs are influenced by thermodynamic equilibrium. DESIGN AND SYNTHESIS OF SUPRAMOLECULAR BIOHYBRID MATERIALS Supramolecular compounds are generally classified into 2 types based on their synthesis and mechanism. They include materials synthesized from onedimensional assembly of stacking and materials synthesized from the chain extension of oligomers of polymeric precursors by corresponding supra molecular recognition motifs. The design of supramolecular materials needs a special understanding of the characteristics of specific non-covalent interactions. This involves the interaction between different supramolecular motifs. In case of

4 Bio-Inspired Nanotechnology

Jyothy G. Vijayan

supramolecular biohybrid materials, assembling of peptides helps to enhance the biomedical application of the materials. These peptides possess sheet-like structure which is joined together by hydrogen bonding. These peptides’ selfassembly gives more advantages to biohybrid materials. It also causes the possibility to mimic the functional and structural aspects of native matrix elements. A new method to synthesize supramolecular biohybrid materials is associated with the crosslinking of polymers and protein-derived molecular recognition motifs [10, 11]. Most identifiable motifs in supramolecular chemistry are the macrocyclic guest-host interaction. Another new method to prepare supramolecular biohybrid material is associated with specific polyvalent Hbonding moieties. It is important to note that complimentary or selfcomplimentary hydrogen bonding moieties can be installed into polymeric backbone through end-functionalized oligomers. DESIGN OF SNPS AS SENSORS AND DRUG DELIVERY SYSTEM Bioconjugation of SNP System Over Metallic Surfaces To increase molecular recognition characteristics, supramolecular system needs to be implied in nanosensor applications. To assemble supramolecular systems as signal transducers on metallic, glass and polymeric surfaces, the chemical structure, host structure and material surface need to be identified. Bioconjugates of surface chemistry include the functional groups such as amine, thiol, carboxyl, aldehyde, epoxy, etc.. Macrocycles can be modified by adding linkers into the matrix to follow bioconjugation. Supramolecular chemistry with optics exhibits higher optical signal for organic molecule detection [12]. Nanoaggregation as Signal Transducers In colloidal system, it is very difficult to modulate the nanoaggregation. It is also difficult to apply the processing to a molecular system where non-covalent interactions exist. Macrocycles work as molecular receptors due to their hostguest structure and the formation of complexes [13]. It allows nanoaggregation and helps to identify the molecules. DESIGN OF SUPRAMOLECULAR POLYMERIC NANOPARTICLES Supramolecular polymers aroused great interest among researchers over the past few decades. Non-covalent interactions have a strong influence on the behaviour of polymer chains. They also have a strong effect on the functionalization of supramolecular self-assembly. Such forces are called supramolecular forces.

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Polymer nanoparticles are hydrophilic or hydrophobic in nature (Tables 1 and 2). They are classified into nanospheres and nanocapsules. Manipulated properties are gained by varying the parameters such as the size, width, the nature of the particle, surface-to-volume ratio, composition, interactions, biochemical moeities, ionic strength, etc.. Altering the composition of the materials for the synthesis of PNPs can also enhance the bioactivity of the molecules. NP enhances drug solubility, therapeutic index of the drug, drug oral bioavailability etc.. Polymeric nanoparticles are composed of a different array of polymers, which have properties like pH, biodegradability, temperature responsiveness, etc.. Natural and synthetic polymers are used in the fabrication of hydrophobic PNPs. They include PVA, PEG, PVP, PAA, etc.. Synthetic polymers are mainly used for the preparation of hydrophobic nanoparticles [14 - 17]. In the development of the synthesis of PNPs, many polymer-related factors have to be taken care of. These factors are responsible for the intrinsic properties of the polymers. Two factors such as surface charge and distribution of functional groups are responsible for the interference of supramolecular interactions. Table 1. Natural polymers and method of synthesis. Type

Polymer

Method of Synthesis

Product Type

References

Natural hydrophilic polymer

Chitosan(cationic)

Ionic gelation

Polyelectrolyte complexes

[18]

Natural hdrophilic polymer

Xanthen(anionic)

Emulsion

Polyelectrolyte complexes

[19]

Natural hdrophilic polymer

Pectin (anionic)

Ionic gelation

Nanogel formation

[20]

Natural hdrophilic polymer

Guar gum (anionic)

Ionic gelation

Polyelectrolyte complexes

[21]

Natural hydrophilic polymer

Albumin (amphibilic)

Nano-precipitation

Polyelectrolyte complexes

[22]

Natural hydrophilic polymer

Starch (anionic)

Nano-precipitation

Polyelectrolyte complexes

[23]

Table 2. Synthetic polymers and method of synthesis. Type

Polymer

Method of Synthesis

References

Synthetic hydrophilic polymer

PEG (non-ionic)

Nano-precipitation

[24]

Synthetic hydrophilic polymer

PAA (anionic)

Emulsion

[25]

Synthetic hydrophilic polymer

PVA (nonionic)

Nano-precipitation

[26]

Synthetic hydrophilic polymer

PVP (non ionic)

Nanogel formation

[27]

Synthetic hydrophobic polymer

PS

Emulsions

[28]

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(Table 1) cont.....

Type

Polymer

Method of Synthesis

References

Synthetic hydrophobic polymer

PLGA

Emulsions

[29]

Synthetic hydrophobic polymer

PACA

Emulsions

[30]

ADVANTAGES OF SUPRAMOLECULAR BIOHYBRID MATERIALS Enhanced attributes of supramolecular biohybrid nanoparticles include modularity, mechanical tunability, responsiveness and biomimicry which help to apply them to different applications. It is due to their tunable, specific and reversible character. Modularity Supramolecular interactions are highly unique and specific in nature. The modularity of supramolecular hybrid nanomaterials allows control over other SNP materials on special properties such as composition, functionality and bioactivity. Modularity of the molecule helps to bring the need of facile modification with diverse targeting ligands. Modularity also helps to display a wide range of signals which is a function of time [31 - 33]. Dynamic Reciprocity Non-covalent interactions and their dynamic nature cause supramolecular materials to respond to multivarious external stimuli. These stimuli are classified as physical, chemical and biological cues. Physical cue involves temperature, light, pH, voltage, ionic strength, redox reagent, etc.. Biological cues involve enzymes, proteins, etc.. The dynamic and responsive properties of the supramolecular system have a great influence on the sensing and responsive characteristics [34 - 36]. Biomimicry Biological systems are diverse and complex in nature and require a novel method to develop synthetic materials which are capable of replicating the entire structure. The functional complexity of biological material leads to develop a true mimetic system with enhanced therapeutic functions. Biohybrid materials that can retrieve signalling pathways are effective for application in regenerative medicine, biomedical or tissue engineering. Here supramolecular hybrid materials act as scaffolds and mimic as fibrous matrix components [37 - 39].

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CHARACTERIZATION TECHNIQUES USED IN SUPRAMOLECULAR CHEMISTRY The properties and structure of SNPs have s strong impact on biological response structure. It includes the shape and properties of the structure and defines some critical factors that characterize the state of the delivery system such as size, surface area and surface charge. The following section provides different physicochemical characteristics of SNPs. Small and Wide Angle X-ray Scattering (Saxs and Waxs) These are used to obtain structural information from nanoparticles. Both techniques give information and complimentary data related to the structural analysis of SNPs. SAX and WAX are used to study shape, crystallinity, orientation, etc.. Crystallinity gives the measure of the degree of structural array and order of SNP system [40 - 44]. Dynamic and Static Light Scattering (DLS and SLS) Both are two complementary methods to characterize the attributes of NPs in the system. Both techniques give information about diffusion, weight, particle size, molecular weight and size. Polymer-based SNP system for drug delivery is based completely on the polymer -polymer or drug- polymer interactions. DLS technique provides size distribution data by measuring the volume, number and intensity [45 - 47]. Calorimetry Micro calorimetry is used to measure heat changes with respect to different physical, chemical and biological processes. Calorimetry is used to characterize the supramolecular NPs. Here the process is described as supramolecular covalent interactions which is the reason for the basis of self-assembly of NPs and their association with biological variants. It is highly efficient during the preparation and application of studies related to biointeraction. Micro calorimetric techniques such as Differential Scanning Electron Microscopy DSC, Isothermal titration calorimetry (ITC), and Pressure perturbation calorimetry (PPC) are used for the supramolecular design of NPs. Through calorimetric techniques, it is easy to gain knowledge related to thermodynamics of supramolecular forces that modulate, nucleate and also stabilize NPs. DSC, PC and ITC are used to characterize molecular interactions during the development of NPs and the stability of the supramolecular system DSC is used to find Tg and melting point. They are used to quantify molecular interactions [48 - 51].

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Fourier Transform Spectroscopy FT-IR Its working principle is mainly based on light-matter interactions. FT-IR is analyzed by the measurement of ƛ max(wavelength) and intensities of the absorption of infrared radiation on the SNP samples. FT-IR provides details of the vibration signature of chemical bonds. This technique is rapid, precise and nondestructive [52]. Ultra Violet-visible Light Absorption Spectroscopy UV-Vis light absorption spectroscopy is applied to the principles of light absorption by a material relative to wavelength. This method is used to study the self-assembled SNPs and their degradation. UV-Vis curve gives information on NPs’ electronic properties. It depends on NPs size distribution, agglomeration and optical properties [53]. Fluorescence Spectroscopy It is used to characterize fluorescent NPs, their concentration, brightness, hydrodynamic radius, etc.. Emission results from the excited state and is also independent of its excitation wavelength. Fluorescence emission contributes to fluorophore de-excitation, radiation loss, phosphorescence, etc.. [54]. Nuclear Magnetic Resonance Spectroscopy This spectroscopy is used for the analysis of conformational and structural details of SNP molecules. NMR is a technique that is based on the absorption of radio frequency energy by a nucleus in the magnetic field. NMR spectroscopy is used for the design of polymer SNPs. NMR is related to the chemical identity and molecular mobility of complex inhomogeneous mixtures. NMR is used to get data related to chemical exchange, domain sizes, function of paramagnetic centers, etc.. NMR is a highly efficient, non-destructive technique that needs no preparation of samples with no structural deterioration [55]. Scanning Electron Microscopy SEM is a microscopic technique that uses an electron beam to analyze the NPs. It is used to characterize hydrophilic and hydrophobic SNPs. It also analyzes the morphological properties of NPs such as particle shape, size distribution, surface functionality, agglomeration, etc.. SEM is used for the visualization of small particles [56].

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Transmission Electron Microscopy TEM is used to analyze internal properties and structure due to its high resolution in spatial and atomic mode. TEM is used to analyze surface morphology such as size, surface quality, external morphology, etc.. [57]. Atomic Force Microscopy It is a three-dimensional measure to study topography at the nanometric range. AFM is the technique used for hydrophobic and hydrophilic NP designing. AFM analyzes the morphology of NPs through different variants such as size, height, radius, width, etc.. AFM is applied for the higher resolution of NPs. AFM is influenced by the agglomeration or inhomogeneity of NPs. AFM is an easy invasive method [58]. APPLICATIONS NANOMATERIALS

OF

SUPRAMOLECULAR

BIOHYBRID

Drug Delivery A number of strategies have been developed to tune the properties of supramolecular systems and to modulate their kinetics. These include monitoring the strength or dynamics of supramolecular interaction. In case of controlled drug delivery, proteins and other biological materials which are generally used to prepare supramolecular biomaterials are leveraged. It mainly aims to control the release of the drug. Another method for administering protein drugs to the supramolecular material involves the demonstration of high-density specific binding sites in the complex matrix. Among drug delivery applications, cancer is one area where supramolecular hybrid biomaterials are applied as an economical drug with creative therapeutic approaches [59 - 61]. Regenerative Medicine Supramolecular materials are regenerative tissues and organs. They involve the discovery of injectable supramolecular peptides to enhance neural reconnections. Supramolecular peptides are used as injectable polymer hydrogels. They are efficient to bind and deliver antigenic growth materials. Among supramolecular nanomaterial systems, peptides act as scaffolds to deliver therapeutic cell population and also in enhanced bold perfusion and limb function. Supramolecular biomaterials are also used in cardiovascular regenerative medicine. Supramolecular methods have recently been used for the promotion of hard tissues like bones and teeth.

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Immuno Engineering Supramolecular hybrid nanomaterials are used to modulate the immune system. They are also used for the delivery of immune signals. This method is used for the development of folded protein antigens by using advanced supramolecular fibrillization. This acts as a template for the immune response to the antigen. CONCLUSION AND FUTURE ASPECTS Supramolecular materials are applied in biomedical applications and cancer therapy because of their enhanced nanostructural precision. Supramolecular materials are also used efficiently in the molecular array of stacking to synthesize drug carriers with high aspect ratios. These materials are also used as disease biomarker triggers, and as medicine for metastatic cancer, arteriosclerosis and inflammatory diseases. Synthesis of biohybrid nanomaterials through supramolecular design principles has many benefits. In the present scenario, the development of supramolecular biomaterials is a relatively novel endeavor. Strategies to prepare supramolecular bionanomaterials from small molecule precursors cause low-yielding synthesis procedures. Improvement of efficiency in the synthesis and application is a prior concern. Supramolecular hybrid bionanomaterials also address low cost and easy scale of production. Trials to maximise non-covalent interactions in the synthesis of supramolecular bionanomaterials have shown the low-cost availability of the components. The supramolecular design of SNPs is facing many challenges due to the lack of techniques to identify and explore the interactions, environment and the components of the system. It leads to a specific and unique system of selfassembling. Supramolecular design is the study of the variations in non-covalent interactions to generate a nanostructural system with controlled characteristics. Despite large amount of knowledge about the characterization of supramolecular NPs, much less time and work has been invested in the way of synthesis. This highlights the complexity of the topic in multidisciplinary areas. SNPs and their chemistry offer a novel route to researchers who aim to correlate synthesis, nanostructure and its applications. This review discusses more about supramolecular nanobiomaterials with applications towards the design of new materials. Supramolecular design principles provide a number of advantages in synthesizing stimuli-responsive materials. Along with the advantages of SNPs in the design of therapeutic materials, the clinical use of the system is explored in detail. New ways to synthesize SNPs must give more demand to SNPs in the near future.

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ABBREVIATIONS SNP

Supramolecular nanoparticles

DSC

Differential scanning electron microscopy

NP

Nanoparticles

SAX

Small angle X-ray scattering

PSNP

Polymer-based Supramolecular nanoparticles

WAX

Wide angle X-ray scattering

PVA

Polyvinyl alcohol

SEM

Scanningelectron microscopy

PEG

Polyethylene Glycol

TEM

Transmission Electron Microscopy

PAA

Polyacrylic acid

FT-IR Fourier Transform Spectroscopy PS

Polystyrene

UV-Vis Ultraviolet-Visible light absorption spectroscopy PLGA Poly(lactic)-co-glycolic acid AFM

Atomic Force Microscopy

PACA Poly(alkyl cyanoacrylate) NMR

Nuclear Magnetic Resonance Spectroscopy

DLS

Dynamic Light Scattering

SLS

Static Light Scattering

CONSENT FOR PUBLICATION Not applicable. CONFLICT OF INTEREST The author declares no conflict of interest, financial or otherwise. ACKNOWLEDGEMENTS Declared none. REFERENCES [1]

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Yu J, Ha W, Sun J, Shi Y. Supramolecular hybrid hydrogel based on host-guest interaction and its application in drug delivery. ACS Appl Mater Interfaces 2014; 6(22): 19544-51. [http://dx.doi.org/10.1021/am505649q] [PMID: 25372156]

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Hirst AR, Escuder B, Miravet JF, Smith DK. High-tech applications of self-assembling supramolecular nanostructured gel-phase materials: from regenerative medicine to electronic devices. Angew Chem Int Ed 2008; 47(42): 8002-18. [http://dx.doi.org/10.1002/anie.200800022] [PMID: 18825737]

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Song Z, Han Z, Lv S, et al. Synthetic polypeptides: from polymer design to supramolecular assembly and biomedical application. Chem Soc Rev 2017; 46(21): 6570-99. [http://dx.doi.org/10.1039/C7CS00460E] [PMID: 28944387]

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Bio-Inspired Nanotechnology, 2023, 16-40

CHAPTER 2

Biocompatible Composites and Applications Madhuri Lakhane1,2 and Megha Mahabole2,* 1 2

Dnynopasak College, Parbhani, India Swami Ramanand Teerth Marathwada University, School of Physical Sciences, Nanded, India Abstract: In this chapter, the low-cost, biodegradable absorbents are developed for wastewater treatment. At first, the modification of the procured nano ZSM-5 is executed by means of dealumination and ion exchange process to have de-laminated (D-ZSM-5), Cu-ZSM-5 and Fe-ZSM-5. Furthermore, cellulose nanofibrils (CNFs) are mixed with modified zeolites with varying concentrations (20 and 80 wt%) used for the fabrication of innovative composite films ((D-ZSM-5, Cu-ZSM-5 and Fe-ZSM-5). FTIR, XRD, BETCO2, TGA, and SEM type of characterization techniques are used for the analysis of composites. The prepared composite films are exploited for cationic Rhodamine B (Rh6B) and anionic Reactive Blue 4 (RB4) dye elimination by the activity of adsorption. The effect of contact time, initial dye concentration and pH on the dyes’ adsorption in aqueous buffer solutions is examined. The equilibrium adsorption data are estimated using Langmuir, Freundlich, and Temkin isotherm models. Langmuir isotherm is deemed to be the best-fitting model and the process (kinetics and mechanism) follows pseudo-second-order kinetics, yielding an uppermost adsorption capacity of 34 mg/g, and 16.55 mg/g which is comparable to plane CNF (8.7mg/g) and (0.243mg/g) for cationic Rh6B dye and anionic RB4 dye respectively. Maximum dye removal is observed for a higher amount of (80% ZSM-5) film. The study reveals that ZSM-5/ CNFs films can potentially be used for the removal of cationic and anionic dyes.

Keywords: Adsorption, Adsorption kinetics, BET, Cellulose nanofibrils, Dealumination, Dye modification, Freundlich, FTIR, Ion exchange, Isotherm models, Langmuir, Nanocomposites, Pseudo-first and second order, Reactive blue, Rhodamine B dye, Temkin, TGA, XRD, ZSM-5 zeolite. INTRODUCTION Material production is one of the major contributors to the water pollution. Various textile methods like dyeing, printing, and washing not only involve hazardous and non-biodegradable dyes, chemicals like nitrates, acetic acid, * Corresponding author Megha Mahabole: Swami Ramanand Teerth Marathwada University, School of Physical Sciences, Nanded, India; Email: [email protected]

Kaushik Pal & Nidhi Asthana (Eds.) All rights reserved-© 2023 Bentham Science Publishers

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sulphur, naphthol, formaldehyde-based dye protective representatives, caustic soda-based soaps or enzymes, chromium compounds, but also a number of heavy metals namely copper, arsenic, lead, cadmium, mercury, nickel, cobalt, as well as hydrocarbon-based softeners. Moreover, clothing processes need a lot of water for cleaning of clothes as well as cleaning of related machines, and vessels. Thus, wastewater from the textile industry contains a number of poisonous pollutants which are observed to be very dangerous to the environment. Some of them can be removed by usual methods like chemical, photochemical and biological degradation, membrane filtration, coagulation/flocculation, precipitation, and solvent extraction, but some pollutants cannot be removed. However, it is due to toxicity, non-degradable, stable, and even carcinogenic nature of synthetic dyes, they are posing dismaying environmental problems [1, 2]. Hence, it is necessary to remove these effluents. Adsorption is an efficient, flexible, and economical method used for dye abstraction wherein hazardous dyes adsorb on the adsorbents like activated carbon, clay minerals, and porous materials [3]. Currently, nanocomposite adsorbents are being employed in line for their superior physical and chemical properties like surface area, morphology, structures, stability, and enhanced adsorption capacities [4]. In consequence, a number of nanocomposite adsorbents similar to graphite/Fe3O4 [5], CuO/NiO [4], graphene oxide/magnetite [6], hydroxyapatite/alginate [7], hydroxyapatite/chitosan [8], chitosan-based semi-IPN hydrogel composites [9], reactive resin composite [10], cobalt-hectorite composite [11], zeolite-activated carbon composite [12], carboxyl methyl cellulose–organo-montmorillonite composite [13], bentonite clay/activated charcoal mixture [14], carbon-mineral composite [15] and PVA/ATP composite [16] have been used for adsorption of several dyes. Zeolites belong to a category of pioneering adsorbents due to their well-porous building. The honeycomb-like composition of zeolite comprises a threedimensional frame, carrying a negatively charged matrix [17, 18]. The negative charge is well-regulated by switching with the neighboring cations. Moreover, the high surface area exhibited by the nano form of zeolites is the foremost advantage for a favorable adsorption process to occur [19]. In addition, zeolite is nontoxic and environment-friendly in nature. Hence, zeolite is preferred for the preparation of composites. Moreover, materials with biological origin have been receiving growing attention due to highly ordered structure that ultimately makes up innumerable functional elements. The nature and structure of surface, morphology, and physical and chemical properties decide the unique properties exhibited by natural materials. Certain biological materials are of significant concern as they offer multifunctionality. It is well known that there are various composites of natural origin

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that exhibit extraordinary properties. Hence, the efforts are being made to develop novel composite materials with fascinating properties and functions for their commercial application in environmental protection by introducing bio-based material as reinforcing material. Cellulose nanofibrils (CNFs), a natural polymeric raw material, have also proved themselves as very promising low-cost biocompatible products for environmental remediation [20, 21]. Moreover, their properties such as hydrophilicity, biodegradability, antibacterial nature, and dye adsorption ability make them more valuable. Urruzola et al. used bleached eucalyptus pulp as a raw material for the adsorption of toluene [22]. The synthesized organic cationic cellulose was used for controlling anionic amphiphilic drug and diclofenac sodium by Rodriguez et al. [23]. Khatri et al. used the cationic cellulose fibers for the color yield and dye fixation by dual padding method [24]. Wang et al. prepared the magnesium chitosan combination for the elimination of Congo red dye from an aqueous solution [25]. Krshni et al. used papaya stem fibers for the adsorption of hydrated methylene group [26]. Pei et al. reported the surface quantized cellulose nanofibers (Q-CNF) for adsorption water and anionic dye [27]. Sehaqui et al. used functionalized cationic CNF for the adsorption humic acid and removal of copper and positively charged dye [28]. Li et al. prepared the adsorbents created using maleic anhydride which improved cellulose fibers containing alkali-treated diatomite in support of the elimination of fundamental dyes, such as methylene blue and methyl violet [29]. Also, the nano celluloses and their phosphorylated derivatives have been used by Liu et al. for the adsorption of Ag+, Cu+ and Fe+ from industrial wastes [30]. Literature review indicates that the CNFs, in functionalized or in modified forms, have been used for the adsorption or removal of dyes. However, the adsorption of dyes like Rhodamine B (Rh6B) and reactive Blue 4 (RB4) by CNFs has not been reported so far. Furthermore, there are reports wherein zeolite/cellulose nanocomposites have been prepared using different methods like ionic liquid solvent [31], hydrothermal method [32] and colloidal method [33]. It has been shown that nanocellulose–zeolite composites films, prepared by the colloidal method, yield high mechanical stability up to 10MPa [34] and these composite films, with high bending flexibility and surface area, can be employed for high thiol removal performance [35]. However, such composites have not been used for the removal of cationic and anionic dyes so far. Hence, the present study deals with the modification of ZSM-5 zeolites and preparation of modified zeolite/CNF nanocomposites by solvent casting method. The structural properties of the tailored modified ZSM-5/CNF nanocomposites have been studied by FTIR, XRD, TGA, BET and SEM analysis. These

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composites have been used as adsorbents for cationic (Rh6B) and anionic (RB4) dyes and their dye removal efficiency have been studied by batch adsorption method. The performance is evaluated by applying Lagergen pseudo-first and second order theory and by fitting the obtained data in Langmuir, Freundlich, and Temkin isotherm models. MATERIALS AND METHODS Materials ZSM-5 zeolite powder (size of ≤80 nm and BET surface area of ≥400 m2/gm) being procured from ACS chemicals Medford, USA, is employed during the analysis. Cellulose nanofibrils (CNFs) are ordered online from alibaba.com using website. The dyes that are presented in Fig. (1), are obtained from Sigma Aldrich and the detail characteristics of dyes are as follows: anionic Reactive Blue 4 (RB4, CI. No.61205) has MW of 637.43 and λmax at 595 nm, and cationic Rhodamine B (Rh6B, CI. No.45170) possesses MW of 479.01 and λmax at 584 nm. All the other elements, obtained from Sigma Aldrich, are used as received.

Fig. (1). Chemical structure of dye; a) Cationic Rh6B b) Anionic RB4 dye.

Modification of ZSM-5 Zeolite The Cu and Fe modified ZSM-5 zeolite samples (abbreviated as Cu-ZSM-5 and Fe-ZSM-5) are prepared by ion exchange process illustrated in Scheme 1. Cu (NO3)2H2O and FeCl3.6H2O with ZSM-5 are used as the starting precursors. The de-alumination of ZSM-5 zeolite (D-ZSM-5) is carried through the acid treatment (Scheme 2).

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Scheme 1. Modification of ZSM-5 zeolite by ion exchange as Cu-ZSM-5 and Fe-ZSM-5.

Scheme 2. De-alumination of ZSM-5 as D-ZSM-5.

Preparation of Zeolite/CNF Nanocomposite Films The composite films are prepared by solution casting method. Two different composites, with CNF and zeolite weight ratios of 20:80, 80:20 respectively, are prepared by mixing an appropriate amount of zeolite with CNF solution (0.6 wt %,) via constant stirring process. Mixtures, thus obtained, are then casted on clean petri-dishes and dried up at room temperature for 24 hr. Characterization of Nanocomposite Films The Fourier Transform Infrared (FTIR) spectra are recorded in the absorbance mode using Shimadzu (Japan) make FTIR spectrophotometer (Model 2000) in the attenuated total reflection mode (ATR). The absorbance weights are recorded within the wavelength range of 4000 cm-1– 400cm-1, with 16 scans and a resolution of 4 cm-1. The structural (physical) analysis of the samples is appraised by X-ray diffraction (XRD) analysis using a Rigaku diffractometer with a scanning rate of 2° per min with Cu Kα radiation source (λ = 1.54060 Å) operating at 40 kV and 30 mA for a range of diffraction angle (2θ) amongst 5-60º. The size of crystal (D, nm) is estimated by using Scherrer’s calculation: D = K *λ/β* cos θ

(1)

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Where K is the shape factor (K=1 for spherical particles), λ is the X-ray wavelength (1.5418Å) in the case of Cu Ka radiation), β is the line width at half the reflection maximum (FWHM), and θ(°) is the corresponding Bragg angle. The crystalline index (CrI) of the composite films is calculated by using equation (2): (2)

CrI (%) = [SC/ (SC+SA)] *100

Where SC is the surface of the crystalline area, and SA is the surface of the amorphous area. Scanning Electron Microscopy (SEM) is employed to study the surface morphologies of the films. The dried films are sputter-coated using gold and are examined by a microscope (FEI Quanta 200 3D) using back-scattered (BSC) and secondary electron (SE) modes at different magnifications up to 100,000 times. The carbon dioxide sorption isotherms are determined on a Micromeritics ASAP 2020 system in a stable dimension mode. The samples are outgassed at 400°C for 8 h prior to the sorption measurements. The Brunauer-Emmett-Teller (BET) model is applied to calculate the total surface area (SBET) from the adsorption data obtained. The thermogravimetric analysis (TGA) of the nanocomposite films is carried out using Shimadzu. Measurements are carried out by means of independent analyses of each film, under identical atmospheric conditions within a temperature range between 25 and 6000C. The heating rate is 100C min 1. Batch Dye Adsorption Studies Adsorption experiments are brought out by batch technique. Stockpile mixtures with varying dye dilutions namely 1, 2.5, 5, 8.5, 10, 15, 20, 40, 60, 80 and 100 mg/L are made by dispersing suitable quantity of RB4 and Rh6B dyes in milli Q water. Nano composite films of (2x2cm2) dimensions are kept in contact with 15 ml of dye stock solution of concentration and the dye solution is agitated at room temperature with the speed of 150 rpm at various time periods. The experiments are conducted for variable pH values of 4.5, 7 and 8.5. The concentration of dye in a solution, before and after adsorption, is estimated by operating UV–VIS spectrophotometer at 595 nm and 584 nm for RB4 and Rh6B dyes respectively. Dye elemination (%) and the amount of dye adsorbed (qt) per unit mass are calculated using the following equations [36]. 𝐃𝐲𝐞 𝐫𝐞𝐦𝐨𝐯𝐚𝐥 (%) =

(𝐂𝐢−𝐂𝐞) 𝐂𝐢

× 𝟏𝟎𝟎

(3)

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𝐪𝐭 =

𝐕× (𝐂𝐢−𝐂𝐞) 𝐦

(4)

Where qt is the amount of dye adsorbed in(mg/g), Ce is the equilibrium concentration of free dye molecules in the solution (mg/L), Ci is the initial dye concentration (mg/L), V is the volume of solution (L) and m is the mass of adsorbent (g). All the experiments are carried out in triplicate to estimate the standard deviation. The same procedure is applied for other dye solutions also. The amount of dye that is adsorbed on composite film (qt) is then plotted against time (t) and analyzed using various models to obtain the kinetic parameters of adsorption. The equilibrium dye uptake (qe) is also plotted against equilibrium concentration of the dye (Ce) and fitted using various mathematical models to determine the adsorption isotherms. RESULTS AND DISCUSSION Nanocomposite Characterization FTIR Analysis The FTIR spectra of modified zeolite/CNF based nanocomposite films are shown in Fig. (2) are compared with that of plane CNF film and ZSM-5. The FTIR spectrum of CNF includes absorption peaks near 3400, 2903, 1369 and 1030 cm-1 corresponding to OH stretching, C-H stretching, C-H bending and C-OH stretching vibrations, respectively. The absorption peaks present at 3350 (OH), 1220(T-O stretch external), 1060 (asymmetrical stretching of T-O), 805 (tetrahedral vibrations), 550 (five membered ring), 435cm-1(pore opening) confirm the ZSM structure. The presence of peak due to OH group with diminished intensity for composites may be due to the increase in hydrophobicity. The disappearance of peak due to C-H group (~2900 cm-1) confirms the small fraction of CNF in composites. Existence of a small peak at ~1370 cm-1 analogous to the C-H bend over vibrations expected to plane CNF is also found to be present in all composite films. The structure sensitive band at 1220 cm-1 of ZSM-5 attributed to the stretching vibrations of T-O bond decreases in case of nano-composites indicating slight disturbance in the structure [35]. In case of D-ZSM-5/CNF

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Fig. (2). FTIR spectra of a) plane CNF film b) 80% D-ZSM/CNFS, c) 80% Cu-ZSM/CNFs, d) 80% FeZSM/CNFs e) pure ZSM-5.

composite film, the peak due to ZSM-5 can clearly be visualized at 1058 cm-1. However, for Cu-ZSM-5/CNF and Fe-ZSM-5/CNF films, a shift in peak towards lower energy is observed. Furthermore, an evolution of peak at ~912cm-1 is clearly noticed in case of Cu-ZSM-5 and Fe-ZSM-5 based composites. This peak corresponds to Al-OH bending vibrations which may be due to interactions of –OH group from CNF with the ZSM-5 [36]. The intensity of this peak is found to be very weak in case of D-ZSM-5/CNF composite and may be due to dealumination. Furthermore, the sharp peak at ~550 cm-1assigned to double five membered rings, the significance of ZSM-5 zeolite structure, has shifted to higher wavenumber side and become broader in all the nanocomposite films [37 - 39]. This result reveals that the CNFs in the ZSM-5 matrix influence on zeolite crystallinity. Broadening and shifting to lower wavenumber of band between 400450 cm-1, attributed to pore opening or motion of the tetrahedral rings in zeolite indicates a decrease in pore openings for composites [39, 40]. This pore opening shrinkage may be due to zeolite agglomeration after being embedded into the CNF matrix and which can also be visualized from the SEM images of the nanocomposite films. Fig. (3) presents the XRD profiles of zeolite/CNFs nanocomposite films wherein XRD patterns of CNF and ZSM-5 are included for reference. The representative XRD profile of plane CNFs, depicted in Fig. (3a), reveals the existence of peaks

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at 2θ of ~16.20, 18.60 and 23.60corresponding to the planes (101), (10-1) and (020) [33, 25], being typical for cellulose I. Similarly, ZSM-5 zeolite has the characteristic peaks at 2θ values of 7.90, 8.80, 23.20 and 23.90 corresponding to (101), (020), (501), (303) hkl planes respectively [25].

Fig. (3). XRD profiles of a) plane CNF film b) 80% D-ZSM/CNFS, c) 80% Cu-ZSM/CNFs, d) 80% FeZSM/CNFs e) pure ZSM-5.

All nanocomposite films clearly show the presence of key XRD peaks due to ZSM-5. Swelling near 230 may be due to the overlapping of CNF peak (at 2θ =23.60) and ZSM-5 peak (at 2θ =23.90) and may lead to the change in crystallinity of the nanocomposite films. The crystal size, calculated as per Scherrer formula using the FWHM of dominating peak (at 2θ = 23.90), is found to be 23nm for all nanocomposite films and for plane CNFs, it is observed to be 35nm. Table 1 gives information about the crystallite size and the crystalline index (Crl). It can be noted that addition of cellulose results in a decrease in the crystallinity index.

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Table 1. X-ray diffraction data for modified ZSM-5 zeolite and CNFs composite films. Samples CNF ZSM-5

D, nm (101) (10 -1) (020) 22.4

54.72

d-spacing, Ǻ Avg

(101)

(020)

(501)

28.01 35.08 0.215 0.245 0.308

(1 0 1) (0 2 0) (5 0 1)

(1 0 1) (0 2 0) (5 0 1)

CrI, % 6.8 100

31.3

36.6

58.3 41.99 0.104 0.117 0.303

80D-ZSM/CNF 26.36

25.75

18.06 23.49 0.104 0.117 0.304

83

80Cu-ZSM/CNF 26.36

25.75

18.06 23.49 0.104 0.117 0.304

83

80Fe-ZSM/CNF 26.36

25.75

18.06 23.49 0.104 0.117 0.304

83

Fig. (4) illustrates the typical CO2adsorption–desorption isotherm for D-ZS-5/CNFs nanocomposite film with % ratio of 80:20. The adsorption–desorption hysteresis loop shows that the rate of adsorption and desorption is same near relative pressure (p/po)≈ 0.4 indicating the mesoporous nature of adsorbate [41 44]. Similar trends, observed by other nanocomposite films, confirm the mesoporous nature these films. The comparison shows that the adsorption capacity is increased after zeolite loading from 20-80% into the CNFs structure. In case of nanocomposite films with 80%D-ZSM-5, the pore width and the surface area are found to be 2.8nm and 194m2/gm respectively. However, for composite films with Cu-ZSM-5 (80%) and Fe-ZSM-5(80%), the obtained pore size and surface area are found to be nearly 3.3nm and 22m2/gm respectively. A decrease in the surface area may be due to the zeolite agglomeration which can be seen from the SEM images and the accumulation of new cations site on its surface. Hence, it is possible for the Cu 2+ and Fe 3+ ions to occupy the sites in ZSM-5 cages as the size of cage is in the range 6-8 nm and the size of the ions are 0.77 and 0.60 nm respectively. Furthermore, there is a probability for some agglomeration being induced by CNF orientation and assembling in nanocomposites. The surface area and surface roughness have increased compared to that for plane CNFs leading to more adsorption sites for the dyes. Average particle size determined from BET data, presuming that the particles are spherical, is compared with that obtained from XRD. As expected, calculated grain size (DBET) values are observed to be greater than those gained from XRD data (DXRD). The acquired data is inserted in Table 2.

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Fig. (4). BETCO2 adsorption-desorption isotherms of a) 80% D-ZSM-5/CNFs, b) 80%CuZSM-5/CNFs, and c) 80% Fe-ZSM-5/CNFs.

Table 2. Surface area and agglomeration ratio for modified ZSM-5 zeolite and CNFs composite films obtained from BETCO2 analysis. DXRD DBET Agglomeration ratio (nm) (nm)

Sample

Surface area (m2/gm)

Plane CNF

10

35

61

1.74

80% D-ZSM-5

194

23

65

2.35

80% Cu-ZSM-5

22

23

85

2.65

80% Fe-ZSM-5

22

23

85

2.65

The thermograms of composites are depicted in Fig. (5). It can visualize that ZSM-5 zeolite remains thermally stable from RT to 6000c.The CNFs are

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thermally stable in the temperature below 300 0c. Further heating results in weight loss in the temperature range 300-300 0c due to pyrolysis of CNFs. No further degradation is observed for heating beyond 330 0c. All nanocomposites exhibit degradation above 300 0c. The degradation temperatures are found to be 328 0C, 3330C and 333 0C for D- ZSM-5/CNFs, Cu-ZSM-5/CNFs, and Fe-ZS-5/CNFs respectively. Shift around degradation temperature after introduction of CNFs reveals the effect of CNFs addition on thermal stability.

Fig. (5). TGA curves of a) plane CNF film b) 80% D-ZSM/CNFS, c) 80% Cu-ZSM/CNFs, d) 80% FeZSM/CNFs e) pure ZSM-5.

The high magnification SEM images of the plane CNFs and the ZSM-5/CNFs nanocomposites are shown in Fig. (6a - d).

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Fig. (6). SEM images of; a) plane CNF film b) 80% D-ZSM/CNFS, c) 80% Cu-ZSM/CNFs, d) 80% FeZSM/CNFs.

The web-like net structure for the plane CNFs with fiber size in the range 5-10 nm is displayed in Fig. (6a). It also reveals the existence of micropores on the surface. Unevenly distributed bundles of CNFs, single CNFs and highly porous globules like structures are observed on the surface of D-ZSM-5/CNFs composite films which can be visualized from (Fig. 6b). Highly porous spongy nanoclusters are also present on the surface. SEM micrograph for Cu-ZSM-5/CNFs composite film (Fig. 6c) shows the occurrence of highly dense platelet /flakes like the structure of variable shapes and sizes, pores and randomly distributed single cellulose nanofibers. Fig. (6d) depicts that the surface of Fe-ZSM-5/CNFs composite includes a bundle of fibers and platelet structures and small length single fibers distributed on the platelet leading to a leafy structure. Dye Adsorption Analysis: Adsorption Equilibrium and Kinetic In case of D-ZSM-5/CNFs composites, cationic dye is used for the adsorption study, whereas the adsorption study of anionic dye is carried out by Cu-ZS-

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-5/CNFs and Fe-ZSM-5/CNFs composites. It is due to net charge on the surface of D-ZSM/CNFs, Cu-ZSM-5/CNFs and Fe-ZSM-5/CNFs composites. 5

5

4 Qe (mg/g)

Qe (mg/g)

6 6

4 3

2

3 2 1

1

0

0 6

6,5

7

7,5

8

8,5

9

4

4,5

20% D-ZSM 80% CNF

80%D- ZSM 20% CNF

5,5

6

6,5

7

7,5

8

8,5

9

Initial pH

Initial pH

Plane CNF

5

Plane CNF

20% Cu-ZSM 80% CNF

80%Cu- ZSM 20% CNF

Fig. 7. Effect of pH on dye adsorption a) cationic (Rh6B) dye b) anionic (RB4) at concentration (Ci) of 20 mg/L.

The impact of pH and time parameters on the adsorption capacities of plane CNF film and the zeolite/CNF composite films for the adsorption of cationic Rh6B and anionic RB4 dyes is shown in Fig. (7). Fig. (7) reveals that the adsorption of dye is independent of the change in pH concentration. The adsorption performance of various dyes as a function of time for all concentrations used for D-ZSM-5 zeolite composites is presented in Fig. (8a). The trend is found to be same for all concentrations, however, the adsorption efficiency increases with an increase in D-ZSM-5zeolite concentration. The adsorption efficiency initially increases rapidly in the first 3 hrs, the adsorption rate slows down thereafter and finally reaches a maximum in about 6 hrs indicating the saturation limit. The same trend has been shown by all composite films. Fig. (8b) reveals the adsorption isotherms for anionic dyes for Fe-ZS-5/CNFs and Cu-ZSM-5/CNFs composites. These films also show a similar trend of initial fast increase followed by slow adsorption and saturation thereafter. The Fe-ZSM-5/CNFs composite film offers the higher adsorption efficiency than CuZSM-5/CNFs film. This may be due to more cationic nature of Fe ions. It is observed that the higher the zeolite concentration, the higher the adsorption efficiency.

Lakhane and Mahabole

6

6

5

5 Qe (mg/g)

Qe (mg/g)

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4

3 2

4

3 2 1

1

0 0

0

0

200

400

600

800

1000

1200

1400

20% D-ZSM 80% CNF

400

600

800

1000

1200

1400

1600

Time (min)

Time (min)

Plane CNF

200

1600

80%D- ZSM 20% CNF

Plane CNF

20% Cu-ZSM

20% Fe-ZSM

80% Fe- ZSM

Cationic dye RhB4

80%Cu- ZSM

Anionic dye RB4

Fig. (8). Effect of contact time on dye adsorption a) cationic (Rh6B) dye b) anionic (RB4) at concentration (Ci) of 20 mg/L.

50

5

0

0 1 2.5 5 8.5 10 15 20 40 60 80 100

10

Conc . (mg/L) Plane CNF 20%D- ZSM 80% CNF

Cationic dye RhB4

150

15

100

10

50

5

0

Qe mg/g)

% dye removal

100

Qe (mg/g)

15

150

% of dye removal

The effect of cationic and anionic dye concentration on adsorption performance is shown in Fig. (9a and b). The dye removal capacity and adsorption efficiency are found to be the function of dye concentration. Fig. (9a) reveals that the adsorption is low for lower dye concentrations up to 5mg. It increases linearly with an increase in the concentration from 5mg to 60 mg and further increase in concentration leads to saturation limit.

0 1

5

10 20 60 100 Conc. (mg/L) Plane CNF 20%Cu- ZSM 80% Cu-ZSM 20%Fe- ZSM 80% Fe-ZSM

Anionic dye RB4

Fig. 9. Effect of initial dye concentration on; a) cationic Rh6 b) anionic RB4 dye.

Thus, bare CNFs and D-ZSM-5/CNFs composite films with 20% and 80% DZSM-5 concentration can remove cationic dye with maximum 60 mg concentration. The dye removal efficiency and adsorption capacity enhance with an increase in D-ZSM-5 amount in composites. The anionic dye removal performances also get augmented for Fe- ZSM-5/CNFs compared to Cu-ZS-5/CNFs films.

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Adsorption Kinetics Lagergen pseudo-first order and pseudo-second order models [45] are used to investigate the mechanism of adsorption, being expressed by: (5)

Log (qe-qt) = log qe – (k1/2.303)

(6)

t/qt = 1/h + (1/qe)t

where qe and qt are amounts of dye adsorbed (mg/g) on adsorbent at equilibrium and at time t, respectively and k1 is the rate constant of pseudo first order adsorption and h is the initial adsorption rate. The pseudo first order and pseudo second order adsorption kinetics for cationic dyes are presented in Fig. (10a and b) respectively and that for (The adsorption kinetics for) anionic dyes are shown in Fig. (10c and d). Pseudo-first order

Pseudo-second order

a

Time (min) 0 200

400

600

800

1000

-1

1200

1400

1600

y = -0,0003x - 0,5539 R² = 0,9052

-1,5

y = -0,0008x - 0,6582 R² = 0,7456

-2

-2,5

y = -0,0013x - 0,7997 R² = 0,8542

-3

t/qt

-0,5

0

1600 1400 1200 1000 800 600 400 200 0

y = 0,7059x + 147,38 R² = 0,9987 y = 0,5943x + 128,05 R² = 0,9938 y = 0,4736x + 108,87 R² = 0,9913

0

200

400

600

-3,5 20% D-ZSM 80% CNF

80% D-ZSM 20% CNF

Pseudo-first order

Plane CNF

1000

1200

1400

1600

200

400

600

800

1000

1200

-1

1600

1400

y = -0,0003x - 0,4373 R² = 0,8308

1200

1400

y = -0,0004x - 0,6958 R² = 0,8321

-1,5

y = -0,0008x - 0,883 R² = 0,9414

-2

80% D-ZSM 20% CNF

y = 0,8871x + 101,33 R² = 0,9949

d

1600

y = 0,8551x + 118,91 R² = 0,9912 y = 0,7581x + 149,6 R² = 0,9913

1000 t/qt

0

20% D-ZSM 80% CNF

Pseudo- second order

c

Time (min) 0

log (qe-qt)

800

Time (min) Plane CNF

-0,5

b

y = 0,613x + 113,02 R² = 0,9907

800

y = 0,4353x + 22,773 R² = 0,9901

600

y = -0,0008x - 0,8027 R² = 0,9198

400

-2,5 -3

y = -0,0012x - 0,9424 R² = 0,9484

0

200 0

200

400

-3,5

600

800

1000

1200

1400

1600

Time (min)

Plane CNF

20% Cu-ZSM

80%Cu- ZSM

20% Fe-ZSM

80% Fe-ZSM

Plane CNF

20% Cu-ZSM

80%Cu- ZSM

20% Fe-ZSM

80% Fe-ZSM

Fig. (10). The pseudo-first order and pseudo-second order adsorption kinetics for 20 mg/L of cationic Rh6B and anionic RB4 dyes, and corresponding intra particle diffusion plots.

32 Bio-Inspired Nanotechnology

Lakhane and Mahabole

The fitting parameters of adsorptions kinetics for two different types of dyes are listed in Table 1. Data presented in Table 1 proposes that the dye adsorption kinetics to all film composites follows the pseudo-second-order model since the correlation coefficient (R2>0.99) obtained by this model is very near to ideal value of 1 compared to that obtained for first order model. These results suggest that the adsorption process is controlled by chemisorption. From Table 1, it can be concluded that the correlation coefficient (R2) is closer to the ideal value in case of a composite film with higher D-ZSM-5 concentration. Similarly, Fe-ZSM-5/CNFs composite film exhibited higher correlation coefficient for anionic dyes than that for pure CNFs and Cu-ZSM-5/CNFs films. These results are in consistence with Langmuir adsorption isotherm. The pseudo-first order and pseudo-second order models are not able to identify the diffusion mechanism, hence the intra-particle diffusion model is considered. This model is expressed by equation [44]. (7)

q t =k i t 1 / 2 +C

Where ki is the intra-particle diffusion constant and C is the intercept associated to the diffusion boundary layer thickness. This model is based on the diffusion of cationic and anionic dyes through composite films and is presented by the plots of qt versus t1/2 for both types of dyes as shown in Fig. (10a and b). The plot shows linear nature followed by plateau region showing saturation. The plots are not passing through origin. It implies that the adsorption is not solely due to the intra-particle diffusion mechanism. The values of kint and C are determined from the slopes of the linear plots, and the constants of intra-particle diffusion model are given in Table 3. Table 3. Adsorption kinetic parameters for modified ZSM-5 zeolite and CNFs composite films as per pseudo first and second order models. Pseudo-second order

Pseudo-first order K q (min-1 m R2 (mg/g) )

Stand. K qm h error (g/mg.min) (mg/g) (mg/g.min)

R2

Intra-particle diffusion model K Stand. i (mg/(g/min C error 0.5 )

R2

Cationic dye Rh6B Plane CNF

0.0018 0.2197 0.7456 0.172

20% D0.0029 0.1586 .8542 ZSM

0.020

0.0034

1.41

0.006

0.9913 0.025

0.0558

0.5418 0.8917

0.0021

1.82

0.007

0.9938 0.026

0.1026

0.8524 0.9121

Bio-Inspired Nanotechnology

Bio-Inspired Nanotechnology 33

(Table 3) cont.....

Pseudo-second order

Pseudo-first order K q (min-1 m R2 (mg/g) ) 80% D0.0006 0.2793 .9052 ZSM

Stand. K qm h error (g/mg.min) (mg/g) (mg/g.min) 0.034

.00200

2.11

0.009

R2

Intra-particle diffusion model K Stand. i (mg/(g/min C error 0.5 )

R2

0.9987 0.014

0.1286

1.522 0.9029

0.00252

0.1291 0.9686

Anionic dye RB4 Plane CNF

0.0006 0.1142 0.8308 0.050

0.007

1.13

0.006

0.9901 0.025

20% 0.0009 0.1309 0.8314 0.074 Cu-ZSM

0.003

1.17

0.008

0.9907

0.03

0.019

0.4199 0.8668

80% 0.0018 0.2015 0.9414 0.072 Cu-ZSM

0.004

1.32

0.008

0.9912 0.046

0.0669

0.7145 0.9855

20% Fe0.0018 0.1575 0.9198 0.094 ZSM

0.004

1.63

0.008

0.9913 0.040

0.0284

0.5533 0.8968

80% Fe0.0027 0.3653 0.9484 0.108 ZSM

0.008

2.3

0.043

0.9947 0.036

0.0656

1.2337 0.9841

The obtained dye adsorption data / isotherms are fitted in Langmuir, Freundlich and Temkin models for adsorption. Fig. (11) describes adsorption isotherm for cationic and anionic dyes as per the Langmuir model. It is well known that the Langmuir adsorption is valid for monolayer adsorption of adsorbate within the adsorbent containing a finite number of identical sites. The model presumes indistinguishable energies of adsorption onto the surface and no migration of the adsorbate in the plane of the surface. Based upon these assumptions, Langmuir adsorption is symbolized by the following equation [45]. qe = qm k Ce/1 + k Ce The equation can also be presented as: 1/qe = 1/qm +1/qm k * 1/Ce

(8)

Where qm (mg/g) is the uppermost monolayer coverage capacity and k is the Langmuir constants, determined by plotting (1/qe) versus (1/Ce), representing the maximum adsorption capacity and energy constant linked to the heat of adsorption capacity. It is observed that the maximum monolayer coverage capacity (qm) is ~34.36 mg/g of cationic dye for 80D-ZSM and ~16.55 mg/g for anionic dyes for 80Fe-ZSM CNF-based composite films with isotherm constant (k) of 0.0088 L/mg and 0.0121 L/mg, respectively, fitting well for all the films as

34 Bio-Inspired Nanotechnology

Lakhane and Mahabole

values of R2 is higher than 0.99. The Freundlich isotherm model presumes that adsorption occurs on a heterogeneous surface through a multi-layer adsorption mechanism and the adsorbed amount increases with the concentration conferring to the following equation [46, 47].

6

12

y = 3,974x + 0,0837 R² = 0,9965

4 3

y = 3,2932x + 0,0291 R² = 0,9996

2 1

Anionic RB4

8

y = 6,8958x + 0,2518 R² = 0,9924 y = 6,128x + 0,6442 R² = 0,9917

6

y = 4,9831x + 0,0604 R² = 0,9984

4

2

0

y = 3,728x + 0,1084 R² = 0,9983

0

0

0,2

0,4

0,6

0,8

1

1,2

Freundlich isotherm

1

Cationic Rh6B

log qe

0,5

Plane CNF

y = 0,8295x - 0,4221 R² = 0,9735

0,5

1

1,5

1

y = 0,6801x - 0,6212 R² = 0,8956

0,5

2

2,5

-0,5 log Ce

Plane CNF

10

8

20% D-ZSM-5

Tempkin isotherm

0,8

1

20% Cu-ZSM

80%Cu- ZSM

20% Fe-ZSM

y = 0,8762x - 0,6565 R² = 0,9905 y = 0,7431x - 0,5371 R² = 0,9776 y = 0,8578x - 0,8758 R² = 0,9898

Freundlich isotherm

Anionic RB4

y = 0,5288x - 0,7156 R² = 0,9664

0

0,5

1

1,5

20% Cu-ZSM

80%Cu- ZSM

-1,5

80% D-ZSM-5

2

2,5

y = 0,1194x - 0,8591 R² = 0,5517

y = 1,7529x - 0,1864 R² = 0,9312

2

0 1

12

1,5

2

2,5

80% Fe- ZSM

y = 6,7676x - 4,1485 R² = 0,9131 y = 5,4582x - 2,8543 R² = 0,9052

Anionic RB4

y = 4,0652x - 2,5918 R² = 0,882 y = 1,0084x - 0,2105 R² = 0,9754

6

4 2

0 -2

0

0,5

1

1,5

2

y = 0,0427x + 0,145 R² = 0,5669

2,5

log Ce

-4

log Ce

20% Fe-ZSM

Tempkin isotherm

10

y = 4,0786x - 1,4261 R² = 0,9721

4

0,5

log Ce Plane CNF

8

Cationic Rh6B

-4

1,2

80% Fe- ZSM

0

y = 6,8344x - 3,1359 R² = 0,9727

6

-2 0

0,6

-1

-1,5

12

0,4

-0,5

-1

14

1,5

y = 0,7967x - 0,5353 R² = 0,9417

0 0

0,2

1/Ce (L/mg)

80% D-ZSM-5

qe (mg/g)

1,5

20% D-ZSM-5

log qe

Plane CNF

0

-2

1/Ce

qe (mg/g)

y = 5,7699x + 4,1175 R² = 0,9616

Langmuir isotherm

10

Cationic Rh6B

5 1/qe

y = 6,4302x + 0,1144 R² = 0,9953

Langmuir isotherm

7

1/Qe (g/mg)

8

-6 Plane CNF

20% D-ZSM-5

80% D-ZSM-5

Plane CNF

20% Cu-ZSM

80%Cu- ZSM

20% Fe-ZSM

80% Fe- ZSM

Fig. (11). Adsorption isotherms of cationic Rh6B and anionic RB4 dyes; a) Langmuir, b) Freundlich and c) Tempkin models.

logqe = log Kf + 1/n log Ce

(9)

Where qe and Ce are the adsorption capacity adsorbed at equilibrium and

Bio-Inspired Nanotechnology

Bio-Inspired Nanotechnology 35

equilibrium concentrations of the adsorbate respectively, while the constant Kf is an indicator of Langmuir adsorption constant, while 1/n is a function of the strength of adsorption in the adsorption process, respectively (n is a constant which depends upon the nature of adsorbent and the gas at a given temperature). The isotherm is positive when n>1, linear when n=1 (the partition between the two phases is independent of the concentration) and negative when n