Dyes, pigments and metals are extensively used in food, paper, carpet, rubber, plastics, cosmetics, and textile industries, in order to color and finish products. As a result, they generate a considerable amount of coloured wastewater rich in organic, inorganic, and mineral substances which are continuously polluting the water bodies and affecting human and aquatic life. Besides these industries, urban and agricultural activities also generate effluents high in biochemical oxygen demand (BOD) and chemical oxygen demand (COD). In recent years, considerable research work has been done in this area and is underway to eliminate heavy metals particularly mercury (Hg), chromium (Cr), lead (Pb), selenium and cadmium (Cd) and synthetic dyes from polluted waters which have high toxicity and carcinogenicity.
Currently a number of methods are in operation to decontaminate the polluted waters. Among several purification technologies, use of nanoparticles/composites have gained much attention as efficient purification technology due to its many advantages such as simple synthesis, special chemical and physical properties, unique photocatalytic activity and beneficial antimicrobial properties and high efficiency. The book Environmental Nanotechnology for Water Purification comprehensively covers and provides new insights on all nanoparticles, composites and advanced methods employed in water purification.
Table of Contents
Preface xiii
1 Environmental Toxicity of Nanoparticles 1
Mohammad Shahadat, Momina, Yasmin, Suzylawati Ismail, S. Wazed Ali and Shaikh Ziauddin Ahammad
1.1 Introduction 2
1.1.1 Toxicity of Nanoparticles in Wastewater Bodies 3
1.1.2 The Effect of Nanoparticles Toxicity on Human Health 4
1.1.2.1 Entry of Nanoparticles into Environment 11
1.1.2.2 Exposure of Nanomaterials 13
1.1.2.3 Consumption of Nanoparticles Through Inhalation and Injection 14
1.1.2.4 Penetration of NPs Through Skin 16
1.1.3 In Vitro Toxicity of Nanoparticles 17
1.1.4 Methods for Assessment of Nanoparticles Toxicity 21
1.1.4.1 Proliferation Assays 21
1.1.4.2 Necrosis Assay 22
1.1.4.3 Apoptosis Assay 22
1.1.4.4 Oxidative Stress Assay 23
1.2 A Critical Evaluation of Challenges and Conclusions 23
Acknowledgement 24
References 24
2 Conventional and Advanced Technologies for Wastewater Treatment 33
S. Bairagi and S. Wazed Ali
2.1 Introduction 34
2.2 Water Filtration by Various Technologies 35
2.3 Conventional Technologies 36
2.3.1 Sedimentation 36
2.3.2 Flocculation 37
2.3.3 Adsorption 38
2.3.4 Filtration 39
2.3.5 Coagulation 40
2.4 Advanced Technologies 41
2.4.1 Water Filtration Using Nanofibrous Membrane 41
2.4.1.1 Removal of Heavy Metal from the Wastewater 42
2.4.1.2 Removal of Microorganisms from Water 45
2.4.1.3 Removal of Dye from Water 49
2.5 Conclusion 53
References 54
3 Nanocarbons-Mediated Water Purification: An Application Towards Wastewater Treatment 57
Vinchurkar, Prasen and Shah, Sejal
3.1 Introduction 58
3.2 Importance of Various Nanocarbons in Water Purification 60
3.3 Various Methods of Nanocarbon-Mediated Purifications of Water 62
3.3.1 Nanocarbon Adsorption (Carbon-Based Nanoadsorbents) 62
3.3.2 Graphene Sieves and CNTs’ Membranes Membrane Process 71
3.3.2.1 CNT’s Membranes and Membrane Process 75
3.3.3 Carbon Nanofiber Membranes 77
3.3.4 Nanocarbon Composite Membranes 82
3.3.5 Antimicrobial Actions of Various Nanocarbons 83
3.4 Regeneration or Recycling of Nanocarbons 83
3.5 Safety, Toxicity, and Environmental Impact of Broad Spectrum of Nanocarbons 84
3.6 Limitations and Research Needs 87
3.6.1 Limitations 87
3.6.2 Research Needs 87
3.7 Conclusion 87
References 88
4 Graphene-Based Nanocomposites for Photocatalytic Dye Degradation Applications 101
Khursheed Ahmad and Waseem Raza
4.1 Introduction 102
4.2 Graphene-Based Composites as Photocatalysts 104
4.2.1 Graphene/ZnO as Photocatalyst 104
4.2.2 Graphene/TiO2 as Photocatalyst 113
4.3 Conclusion 117
Acknowledgments 117
References 117
5 Synthesis of Stable and Monodispersed Cobalt Nanoparticles and Their Application as Light-Driven Photocatalytic Agents for Dye Degradation 123
Farzana Majid, Sadia Ata, Nida Sohaib, Imran Deen, Adnan Ali, Ismat Bibi, Munawar Iqbal and Arif Nazir
5.1 Introduction 124
5.2 Materials and Methodology 125
5.2.1 Materials 125
5.2.2 Synthesis of Co Metal NPs 125
5.2.3 Photocatalytic Process 128
5.2.3.1 Photocatalytic Experiment 128
5.2.4 Characterizations 129
5.3 Results and Discussion 129
5.3.1 Physiochemical Characterization of Co Metal NPs 129
5.3.1.1 Ultraviolet Visible Spectrometer (UV-Vis) 129
5.3.1.2 Effect of Reaction Parameters on the Optical Properties of Co NPs 130
5.3.1.3 Effect of Concentration of Salt on the Optical Properties of Co NPs 131
5.3.1.4 Effect of pH of Reaction Medium on the Optical Properties of Co NPs 132
5.3.1.5 Effect of Reaction Temperature on the Optical Properties of Co NPs 132
5.3.1.6 Effect of Reaction Heating Time on the Optical Properties of Co NPs 132
5.3.2 X-Ray Diffraction Analysis 132
5.3.2.1 X-Ray Analysis of Co Metal NPs 132
5.3.3 FTIR Analysis 138
5.3.3.1 FTIR Interferogram for Co Metal NPs 138
5.3.4 Photocatalytic Properties 139
5.3.4.1 Photocatalysis of Methylene Blue With Co Metal NPs 139
5.3.4.2 Comparison of Activity of Methylene Blue 140
5.3.5 Scanning Electron Microscopy 141
5.3.5.1 SEM Analysis for Co Metal NPs 141
5.3.6 Synthesis of Cobalt Nanoparticles and Their Applications 141
5.4 Conclusion 144
References 145
6 Metal and Metal Oxide Nanoparticles for Water Decontamination and Purification 151
Shams Tabrez Khan, Faizan Ahmad, Mohammad Shahadat, Wasi Ur Rehman and Abu Mustafa Khan
6.1 Introduction 152
6.2 Threats to Drinking Water 153
6.2.1 Suspended Solids in Water 153
6.2.2 Waterborne Pathogens 153
6.2.3 Chemical Pollutants in Drinking Water 157
6.3 Losses Due to Impure Water 158
6.4 Role of Nanomaterials in Water Purification With Special Reference to Metal and Metal Oxide Nanoparticles 160
6.4.1 Titanium Dioxide Nanoparticles for Water Purification 162
6.4.2 The Use of Zinc Oxide Nanoparticle for Water Purification 167
6.4.3 Silver Nanoparticles and Their Possible Role in Water Purification 168
6.4.4 Iron Nanoparticles 169
6.4.5 Nanocomposites With Improved Antimicrobial Activities 169
6.5 Types of Nanomaterials 170
6.5.1 Nanofilters 170
6.5.2 Nanoadsorbents 171
6.5.3 Nanofiber-Based Membranes 171
6.6 Commercially Available Products for Water Purification 171
6.7 Challenges 174
6.7.1 Health or Toxicity Concerns 174
6.7.2 Economic Viability 176
6.7.3 Operational Concerns 176
6.7.4 Legal Constraints and Regulations 177
6.8 Conclusion 177
Acknowledgements 178
References 178
7 Recent Advances in Metal Oxide/Sulphide-Based Heterostructure Photocatalysts for Water Splitting and Environmental Remediation 187
Umar Farooq, Ashiq Hussain Pandit and Ruby Phul
7.1 Introduction 188
7.2 Synthesis of Heterostructures 189
7.2.1 Hydrothermal Method 190
7.2.2 Co-Precipitation Method 191
7.2.3 Sol-Gel Method 191
7.2.4 Dip-Coating 192
7.2.5 Chemical-Vapor Deposition (CVD) Method 192
7.3 Nanostructured Heterostructures for Water Splitting and Organic Pollutant Degradation 192
7.3.1 Metal Oxide/Metal Oxide Heterostructures for Water Splitting 193
7.3.2 Metal Oxide/Metal Sulphide Heterostructures for Water Splitting 197
7.3.3 Photocatalytic Removal of Organic Pollutants by Metal Oxide/Sulphide-Based Heterostructures 202
7.4 Conclusion 209
Acknowledgement 209
References 210
8 Electrospun Nanofibers for Water Purification 217
Ali Akbar Merati and Mahsa Kangazian Kangazi
8.1 Introduction to Electrospinning and Nanofibers 218
8.2 Nanofibers for Wastewater Treatment 218
8.2.1 Nanofibers as Pressure-Driven Membrane 219
8.2.1.1 Nanofibers as Microfiltration Membrane for Wastewater Treatment 220
8.2.1.2 Nanofibers as Ultrafiltration Membrane for Wastewater Treatment 221
8.2.1.3 Nanofibers as Nanofiltration Membrane for Wastewater Treatment 223
8.2.1.4 Nanofibers as Membrane/Mid-Layer for Reverse Osmosis 224
8.2.2 Nanofibers as Membranes for Membrane Distillation 226
8.2.3 Nanofibers as Membrane Support Layer for Forward Osmosis 229
8.2.4 Nanofibers as Electrodes for Capacitive Deionization 230
8.2.5 Nanofibers as Porous Floating Membrane for Solar Steam Generation 231
8.2.6 Nanofibers as Membrane or Adsorbent for Oil-Water Separation 232
8.2.7 Nanofibers as Adsorbent for Removal of Heavy Metal Ions From Water/Wastewater 234
8.2.8 Nanofibers as Photocatalytic Membrane for Water Treatment 235
8.2.9 Nanofibers as Membrane or Adsorbent for Dye Wastewater Treatment 236
8.3 Effects of Different Parameters on Resultant Nanofibrous Membranes 238
8.3.1 Tunable Structural Characteristic of Electrospun Nanofibrous Membranes for Purification of Wastewater 243
8.4 Materials Selection for Nanofibrous Membranes in Water Purification 246
8.5 Conclusion 248
References 249
9 ZnO Nanostructure for Photocatalytic Dye Degradation Under Visible Light Irradiation 259
Waseem Raza and Khursheed Ahmad
9.1 Introduction 260
9.2 Photocatalysis 262
9.3 Enhancement of Photocatalytic Performance of Dare ZnO 264
9.4 Doping With Transition Metals 265
9.4.1 Doping with Rare Earth (RE) Metals 269
Conclusion 277
References 278
10 Nanocatalysts in Wet Air Oxidation 285
Anushree, Sheetal and Satish Kumar
10.1 Introduction 286
10.2 Catalyst Selection Criterion 288
10.3 Nanocatalysts in CWAO 289
10.3.1 Mesoporous Materials 290
10.3.2 Carbon Nanomaterials 293
10.3.3 Nanoparticles 293
10.4 Synthesis of Nanocatalysts 295
10.4.1 Bare-Nanocatalysts 296
10.4.2 Supported Nanocatalysts 297
10.5 Ceria-Based Nanocatalysts for CWAO 298
10.5.1 Synthesis and Characterization 299
10.5.1.1 Synthesis 299
10.5.1.2 Characterization 300
10.5.2 CWAO of Industrial Wastewater 301
10.5.2.1 Chlorophenolics Removal 302
10.5.2.2 Reusability and Leaching Studies 305
10.5.2.3 Kinetic Study 306
10.6 Comparative Study of Different Ceria-Based Nanocatalysts 307
10.6.1 Structural and Textural Properties 307
10.6.2 Treatment Efficiency 308
10.7 Role of Ceria-Based Nanocatalyst in CWAO 309
10.8 Conclusion 310
References 310
