Photocatalysts and Electrocatalysts in Water Remediation: From Fundamentals to Full Scale Applications

334 Pages·2023·10.849 MB·English

by  Bhunia P., Dutta K., Vadivel S. (ed.)

Photocatalysts and Electrocatalysts
in Water Remediation
Photocatalysts and Electrocatalysts
in Water Remediation
From Fundamentals to Full Scale Applications
Edited by
Dr Prasenjit Bhunia
Silda Chandra Sekhar College, India
Dr Kingshuk Dutta
Central Institute of Petrochemicals Engineering and Technology (CIPET), India
Dr S. Vadivel
Saveetha Institute of Medical and Technical Sciences, India
This edition first published 2023
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Cover image: Courtesy of Kingshuk Dutta
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Set in 9.5/12.5pt STIXTwoText by Integra Software Services Pvt. Ltd, Pondicherry, India
v
Contents
Preface ix
About the Editors xi
List of Contributors xiii
Acknowledgements xv
1 F undamentals and Functional Mechanisms of Photocatalysis in
Water Treatment 1
1.1 Introduction 1
1.2 Different Photocatalytic Materials for Water Treatment 2
1.3 In-depth Mechanisms of Photocatalysis 9
1.4 Visible Light Driven Photocatalysts for Water Decontamination 20
1.5 Summary 25
2 Different Synthetic Routes and Band Gap Engineering of Photocatalysts 39
2.1 Introduction 39
2.2 Synthesis of Photocatalysts 40
2.3 Properties of Ideal Photocatalytic Material 57
2.4 Engineering Photocatalytic Properties 58
2.5 Energy Bandgap 59
2.6 Engineering the Desired Band Gap 64
2.7 Photocatalytic Mechanisms, Schemes and Systems 69
2.8 Summary and Perspectives 71
3 Photocatalytic Decontamination of Organic Pollutants from Water 81
3.1 Introduction 81
3.2 Photocatalytic Degradation Mechanisms of Organic Contaminants 82
3.3 A dvanced Photocatalytic Materials for Decontamination of
Organic Pollutants 83
3.4 S olar/Visible-light Driven Photocatalytic Decontamination of Organic
Pollutants 85
3.5 E merging Scientific Opportunities of Photocatalysts in Removal of Organic
Pollutants 87
3.6 L imitations of Photocatalytic Decontamination and Key
Mitigation Strategies 95
3.7 Summary and Future Directions 96
vi Contents
4 Photocatalytic Removal of Heavy Metal Ions from Water 105
4.1 Introduction 105
4.2 Mechanistic Insights on Photocatalytic Removal of Heavy Metal Ions 110
4.3 S olar/Visible-light Driven Photocatalysts for the Removal of
Heavy Metal Ions 113
4.4 Selective Heavy Metal Ion Removal by Semiconductor Photocatalysts 123
4.5 Major Drawbacks and Key Mitigation Strategies 125
4.6 Summary and Future Directions 126
5 Smart Photocatalysts in Water Remediation 135
5.1 Introduction 135
5.2 Advances in the Development of Visible-light Driven Photocatalysts 138
5.3 Advances in Photocatalyst Immobilization and Supports 142
5.4 Advances in Nonimmobilized Smart Photocatalysts 144
5.5 Advances in Improving the Efficiency of Light Delivery 149
5.6 Advances in Biomaterials for Designing Smart Photocatalysts 157
5.7 Advances Toward Improving Photocatalytic Activity via External Stimuli 159
5.8 A dvances in Inhibiting the Photocorrosion of Semiconductor-based
Photocatalysts 164
5.9 A dvances in Recycling Photocatalysts: Assessing the
Photocatalyst Life Cycle 166
5.10 Summary, Future Challenges, and Prospects for Further Research 167
6 F undamentals and Functional Mechanisms of Electrocatalysis in Water
Treatment 189
6.1 Introduction 189
6.2 Electrocatalysis Treatment 190
6.3 Properties and Characteristics of Different Electrocatalysis Techniques 192
6.4 Case Studies and Successful Approaches 202
6.5 Conclusion 217
7 D ifferent Synthetic Routes of Electrocatalysts and
Fabrication of Electrodes 229
7.1 Introduction 229
7.2 Fundamental Principles of Alkaline Water Oxidation 230
7.3 E lectrochemical Evaluating Parameters of Electrocatalysts for OER
Performance 231
7.4 Electrocoagulation 233
7.5 Electroflotation 233
7.6 Electrocoagulation/flotation 233
7.7 Electro-oxidation in Wastewater Treatment 233
7.8 Doped Diamond Electrodes 234
7.9 Conclusion 235
Contents vii
8 Electrocatalytic Degradation of Organic Pollutants from Water 241
8.1 Introduction 241
8.2 Principles and Fundamental Aspects of Electrooxidation 242
8.3 Electrode Materials and Cell Configuration 244
8.4 Performance Assessment Indicators and Operating Variables 250
8.5 Electrochemical Filtering Process: A Hybrid Process Based on
Electrooxidation and Filteri ng 253
8.6 Integration of Electrooxidation-based Processes in Water/Wastewater
Treatment Technological Flow 259
9 Electrocatalytic Removal of Heavy Metal Ions from Water 275
9.1 Introduction 275
9.2 Fundamentals 277
9.3 Advantages and Disadvantages of the Electrocatalytic Approach 283
9.4 Summary 284
10 Combined Photoelectrocatalytic Techniques in Water Remediation 289
10.1 Introduction 289
10.2 Photoelectrocatalysts for Treatment of Water Contaminants 292
10.3 Simultaneous Removal of Organic and Inorganic Pollutants 302
10.4 Conclusions and Perspective 304
Index 311
ix
Preface
A wide array of wastewater treatment alternatives are being investigated nowadays, and
this is owing to the increase in polluted wastewater generation because of the growth in
population and industrial activities. Advanced oxidation processes (AOPs) have become, in
the last few years, a selected alternative due to several advantages, such as their nonselec-
tive degradation of pollutants and their easy setup. Photo-based processes have always
been one of the most preferred AOP options, due to the possibility of using solar radiation
that may reduce the AOPs’ high elevated costs. Photocatalysis processes fall under the AOP
category, and it is studied worldwide for various applications. A photocatalyst is defined as
a “catalyst able to produce, upon absorption of light, chemical transformations of the reac-
tion partners” [1]. The excited state of a photocatalyst interacts repeatedly with the reac-
tion partners, resulting in the formation of reaction intermediates, and regenerates itself
after each cycle of such interactions. In effect, the photocatalyst is activated with radiation,
which brings about the separation of electrons and holes from, respectively, the valence
and conduction bands of semiconductor photocatalysts. This, in turn, starts a series of
chain reactions that lead to the generation of oxidants and, ultimately, to pollutant degra-
dation. However, even photocatalysis has limitations for future applications; for instance,
the electrons and holes are usually recombined, long treatment times are required, etc. As
a solution, the combination of photocatalysis with the application of an electrochemical
field (photoelectrocatalysis) has been contemplated.
On the other hand, electrochemistry, an interdisciplinary field of interfacial charge
transfer, has been introduced for the decontamination of both organic and inorganic pol-
lutants, and therefore has developed significant worldwide interest toward water remedia-
tion. In this connection, electrocatalytic oxidation and reduction usually work together to
decompose organic contaminants, and convert heavy metal ions from their toxic to non-
toxic form in electrocatalytic advance oxidation processes (EAOPs). Although this tech-
nique was elucidated long back in the 1970s, it is only in recent years that the electrocatalysts
have become highly encouraging materials toward water remediation. Electrocatalysts
degrade or convert the contaminants (organic or inorganic) through profound collision of
a very clean reagent – “the electron”; therefore, the technique is recognized as environmen-
tally benign. In addition, this technique has been found to be highly versatile toward deg-
radation of various contaminants, including dyes, pesticides and herbicides, phenolic
compounds, pharmaceuticals, etc., and is also able to convert heavy metal ions from their
x Preface
toxic to nontoxic forms. Moreover, the most attractive features of EAOPs toward water
treatment are high treatment efficiencies, accumulation of less toxic by-products, and envi-
ronmental friendliness.
The subject of this book has been meticulously designed to cover both the photo and
electrocatalytic water remediation aspects, starting from fundamentals to the applications.
This book describes the major functions of catalysts (photo-, electro-, and electrophoto-) in
the domain of water remediation, along with the involved chemical reactions, mecha-
nisms, challenges, and up-to-date developments. In addition, the scope of further research
on photo, electro, and electrophotocatalysts is also thoroughly discussed. Enriched with
critically analyzed and expertly opined contributions from several well-known researchers
around the world, this book is likely to serve as one of the most comprehensive and author-
itative pieces of literature that has ever been published in this field, and will undoubtedly
serve as a potent source of information for those interested in this field.
Prasenjit Bhunia
Kingshuk Dutta
S. Vadivel
Reference
1 IUPAC, (1997) Compendium of Chemical Terminology: The Gold Book. Oxford: Blackwell
Scientific Publications.
xi
About the Editors
Dr. Prasenjit Bhunia has obtained his Masters and Doctorate in Inorganic Chemistry
from Jadavpur University, Kolkata, India. In addition, he has done Post-Doctoral research
at National Taiwan University, Taiwan and Sungkyunkwan University, Suwon, South
Korea, and has gained prolonged experience in Graphene/Graphene Oxide and their func-
tionalization and applications. He has also served as an Institute Post-Doctoral Fellow in
the Department of Chemical Engineering, Indian Institute of Technology Kharagpur,
India, and has gathered significant experience in photocatalysis and electrocatalysis.
Furthermore, he has noticeable industrial experience from working at Hindustan Unilever
Limited, Bangalore and TCG Life Sciences, Kolkata, India. In addition, he has served as a
Principal Researcher at TATA Steel Limited, Jamshedpur, India, where he has gained out-
standing experience in the field of photocatalytic wastewater treatment. Now, he serves as
an Assistant Professor in the Department of Chemistry, Silda Chandra Sekhar College,
Jhargram, India (affiliated to Vidyasagar University, Paschim Medinipur, India). At this
time, he has 23 international peer reviewed journal articles, 7 book chapters and 5 patents
to his credit. His present research field is photocatalytic water treatment.
Dr. Kingshuk Dutta, FICS, is currently employed as a Scientist in the Advanced Polymer
Design and Development Research Laboratory of the Central Institute of Petrochemicals
Engineering and Technology, India. Prior to this appointment, he worked as an Indo–US
Postdoctoral Fellow at Cornell University, USA (2018–19) and as a National Postdoctoral
Fellow at the Indian Institute of Technology – Kharagpur, India (2016–17), both funded by
the Science and Engineering Research Board, Govt. of India. Earlier, as a Senior Research
Fellow funded by the Council of Scientific and Industrial Research, Govt. of India., he had
carried out his doctoral study at the University of Calcutta, India (2013–16). He possesses
degrees in both technology (B. Tech. and M. Tech.) and science (B. Sc.), all from the
University of Calcutta. He was also a recipient of the prestigious Graduate Aptitude Test in
Engineering (GATE) and National Scholarship, both from the Ministry of Human Resource
Development, Govt. of India. His areas of research interest lie in the fields of fuel cells
(including alcohol, bio/microbial, and hydrogen fuel cells), sensors, water purification,
polymer blends and composites, and biodegradable polymers. At this time, he has contrib-
uted to 54 experimental and review papers in reputed international platforms, 25 book
chapters, 1 patent application, and many national and international presentations. In