Photocatalysis and Water Purification : From Fundamentals to Recent Applications

[BOOK DESCRIPTION]

Water is one of the essential resources on our planet. Therefore, fresh water and the recycling of waste-water are very important topics in various areas. Energy-saving green technologies are a demand in this area of research. Photocatalysis comprises a class of reactions which use a catalyst activated by light. These reactions include the decomposition of organic compounds into environmental friendly water and carbon dioxide, leading to interesting properties of surfaces covered with a photocatalyst: they protect e.g. against incrustation of fouling matter, they are self-cleaning, antibacterial and viricidal. Therefore, they are attractive candidates for environmental applications such as water purification and waste-water treatment. This book introduces scientists and engineers to the fundamentals of photocatalysis and enlightens the potentials of photocatalysis to increase water quality. Also, strategies to improve the photocatalytic efficacy are pointed out: synthesis of better photocatalysts, combination of photocatalysis with other technologies, and the proper design of photocatalytic reactors.Implementation of applications and a chapter on design approaches for photocatalytic reactors round off the book. 'Photocatalysis and Water Purification' is part of the series on Materials for Sustainable Energy and Development edited by Prof. G.Q. Max Lu. The series covers advances in materials science and innovation for renewable energy, clean use of fossil energy, and greenhouse gas mitigation and associated environmental technologies.

[TABLE OF CONTENTS]

Series Editor Preface                              xvii
Preface                                            xix
About the Series Editor                            xxiii
About the Volume Editor                            xxv
        List of Contributors                       xxvii
  Part I Fundamentals: Active Species,             1    (72)
  Mechanisms, Reaction Pathways
    1 Identification and Roles of the Active       3    (22)
    Species Generated on Various Photocatalysts
          Yoshio Nosaka
          Atsuko Y. Nosaka
      1.1 Key Species in Photocatalytic            3    (3)
      Reactions
      1.2 Trapped Electron and Hole                6    (1)
      1.3 Superoxide Radical and Hydrogen          7    (2)
      Peroxide (O2 and H2O2)
      1.4 Hydroxyl Radical (OH)                    9    (3)
      1.5 Singlet Molecular Oxygen (1O2)           12   (3)
      1.6 Reaction Mechanisms for Bare TiO2        15   (2)
      1.7 Reaction Mechanisms of                   17   (3)
      Visible-Light-Responsive Photocatalysts
      1.8 Conclusion                               20   (5)
        References                                 21   (4)
    2 Photocatalytic Reaction Pathways --          25   (28)
    Effects of Molecular Structure, Catalyst,
    and Wavelength
          William S. Jenks
      2.1 Introduction                             25   (2)
      2.2 Methods for Pathway Determination        27   (2)
      2.3 Prototypical Oxidative Reactivity in     29   (10)
      Photocatalytic Degradations
        2.3.1 Oxidation of Arenes and the          30   (1)
        Importance of Adsorption
        2.3.1.1 Hydroxylation and the Source of    30   (2)
        Oxygen
        2.3.1.2 Ring-Opening Reactions             32   (1)
        2.3.1.3 Indicators of SET versus           32   (3)
        Hydroxyl Chemistry in Aromatic Systems
        2.3.2 Carboxylic Acids                     35   (1)
        2.3.3 Alcohol Fragmentation and            36   (1)
        Oxidation
        2.3.4 Oxidation of Alkyl Substituents      37   (1)
        2.3.5 Apparent Hydrolysis Reactions        38   (1)
        2.3.6 Sulfur-Bearing Compounds             39   (1)
      2.4 Prototypical Reductive Reactivity in     39   (2)
      Photocatalytic Degradations
      2.5 The Use of Organic Molecules as Test     41   (1)
      Probes for Next-Generation Photocatalysts
      2.6 Modified Catalysts:                      42   (2)
      Wavelength-Dependent Chemistry of Organic
      Probes
      2.7 Conclusions                              44   (9)
        References                                 45   (8)
    3 Photocatalytic Mechanisms and Reaction       53   (20)
    Pathways Drawn from Kinetic and Probe
    Molecules
          Claudio Minero
          Valter Maurino
          Davide Vione
      3.1 The Photocatalyic Rate                   53   (7)
        3.1.1 Other Kinetic Models                 55   (2)
        3.1.2 Substrate-Mediated Recombination     57   (3)
      3.2 Surface Speciation                       60   (5)
        3.2.1 Different Commercial Catalysts       60   (1)
        3.2.2 Surface Manipulation                 61   (1)
        3.2.3 Crystal Faces                        62   (2)
        3.2.4 Surface Traps for Holes              64   (1)
      3.3 Multisite Kinetic Model                  65   (3)
      3.4 Conclusion                               68   (5)
        References                                 68   (5)
  Part II Improving the Photocatalytic Efficacy    73   (198)
    4 Design and Development of Active Titania     75   (28)
    and Related Photocatalysts
          Bunsho Ohtani
      4.1 Introduction -- a Thermodynamic          75   (2)
      Aspect of Photocatalysis
      4.2 Photocatalytic Activity: Reexamination   77   (1)
      4.3 Design of Active Photocatalysts          78   (1)
      4.4 A Conventional Kinetics in               79   (1)
      Photocatalysis: First-Order Kinetics
      4.5 A Conventional Kinetics in               80   (2)
      Photocatalysis: Langmuir--Hinshelwood
      Mechanism
      4.6 Topics and Problems Related to           82   (3)
      Particle Size of Photocatalysts
      4.7 Recombination of a Photoexcited          85   (1)
      Electron and a Positive Hole
      4.8 Evaluation of Crystallinity as a         86   (1)
      Property Affecting Photocatalytic Activity
      4.9 Electron Traps as a Possible             87   (2)
      Candidate of a Recombination Center
      4.10 Donor Levels -- a Meaning of n-Type     89   (1)
      Semiconductor
      4.11 Dependence of Photocatalytic            90   (6)
      Activities on Physical and Structural
      Properties
        4.11.1 Correlation between Physical        90   (2)
        Properties and Photocatalytic Activities
        4.11.2 Statistical Analysis of             92   (2)
        Correlation between Physical Properties
        and Photocatalytic Activities -- a Trial
        4.11.3 Common Features of Titania          94   (1)
        Particles with Higher Photocatalytic
        Activity
        4.11.4 Highly Active Mesoscopic Anatase    95   (1)
        Particles of Polyhedral Shape
      4.12 Synergetic Effect                       96   (1)
      4.13 Doping                                  97   (1)
      4.14 Conclusive Remarks                      98   (5)
        Acknowledgments                            99   (1)
        References                                 99   (4)
    5 Modified Photocatalysts                      103  (42)
          Nurit Shaham-Waldmann
          Yaron Paz
      5.1 Why Modifying?                           103  (1)
      5.2 Forms of Modification                    104  (2)
      5.3 Modified Physicochemical Properties      106  (39)
        5.3.1 Crystallinity and Phase Stability    106  (1)
        5.3.2 Surface Morphology, Surface Area,    107  (4)
        and Adsorption
        5.3.3 Adsorption of Oxygen                 111  (1)
        5.3.4 Concentration of Surface OH          111  (1)
        5.3.5 Specificity                          112  (3)
        5.3.5.1 TiO2 Surface Overcoating           115  (1)
        5.3.5.2 Composites Comprised of TiO2       116  (1)
        and Metallic Nanoislands
        5.3.5.3 Doping with Metal Ions and         116  (1)
        Oxides
        5.3.5.4 Utilizing the "Adsorb and          117  (2)
        Shuttle" Mechanism to Obtain Specificity
        5.3.5.5 Mesoporous Materials               119  (1)
        5.3.5.6 Molecular Imprinting               120  (2)
        5.3.6 Products' Control                    122  (1)
        5.3.6.1 Surface Modification by            123  (1)
        Molecular Imprinting
        5.3.6.2 Composites Comprised of TiO2       124  (1)
        and Metallic Nanoislands
        5.3.6.3 Doping with Metal Ions             124  (1)
        5.3.6.4 Nonmetallic Composite              125  (1)
        5.3.6.5 TiO2 Morphology and Crystalline    125  (1)
        Phase
        5.3.7 Reducing Deactivation                125  (1)
        5.3.8 Recombination Rates and Charge       126  (1)
        Separation
        5.3.8.1 Structure Modification             127  (1)
        5.3.8.2 Composites--Metal Islands          127  (1)
        5.3.8.3 Composites Comprising              128  (1)
        Carbonaceous Materials
        5.3.8.4 Composites Composed of TiO2 and    128  (1)
        Nonoxide Semiconductors
        5.3.8.5 Composites Composed of TiO2 and    129  (2)
        Other Oxides
        5.3.8.6 Doping with Metals                 131  (1)
        5.3.8.7 Doping with Nonmetals              132  (1)
        5.3.9 Visible Light Activity               132  (1)
        5.3.10 Charging--Discharging               132  (1)
        5.3.11 Mass Transfer                       133  (1)
        5.3.12 Facilitating Photocatalysis in      134  (1)
        Deaerated Suspensions
        Summary                                    134  (1)
        References                                 134  (11)
    6 Immobilization of a Semiconductor            145  (34)
    Photocatalyst on Solid Supports: Methods,
    Materials, and Applications
          Didier Robert
          Valerie Keller
          Nicolas Keller
      6.1 Introduction                             145  (2)
      6.2 Immobilization Techniques                147  (5)
      6.3 Supports                                 152  (16)
        6.3.1 Packed-Bed Photocatalytic            153  (2)
        Materials
        6.3.2 Monolithic Photocatalytic            155  (9)
        Materials
        6.3.3 Optical Fibers                       164  (4)
      6.4 Laboratory and Industrial                168  (3)
      Applications of Supported Photocatalysts
      6.5 Conclusion                               171  (8)
        References                                 172  (7)
    7 Wastewater Treatment Using Highly            179  (20)
    Functional Immobilized TiO2 Thin-Film
    Photocatalysts
          Masaya Matsuoka
          Takashi Toyao
          Yu Horiuchi
          Masato Takeuchi
          Masakazu Anpo
      7.1 Introduction                             179  (1)
      7.2 Application of a Cascade Falling-Film    180  (4)
      Photoreactor (CFFP) for the Remediation
      of Polluted Water and Air under Solar
      Light Irradiation
      7.3 Application of TiO2 Thin-Film-Coated     184  (2)
      Fibers for the Remediation of Polluted
      Water
      7.4 Application of TiO2 Thin Film for        186  (1)
      Photofuel Cells (PFC)
      7.5 Preparation of                           187  (8)
      Visible-Light-Responsive TiO2 Thin Films
      and Their Application to the Remediation
      of Polluted Water
        7.5.1 Visible-Light-Responsive TiO2        188  (2)
        Thin Films Prepared by Cation or Anion
        Doping
        7.5.2 Visible-Light-Responsive TiO2        190  (5)
        Thin Films Prepared by the Magnetron
        Sputtering Deposition Method
      7.6 Conclusions                              195  (4)
        References                                 195  (4)
    8 Sensitization of Titania Semiconductor: A    199  (42)
    Promising Strategy to Utilize Visible Light
          Zhaohui Wang
          Chuncheng Chen
          Wanhong Ma
          Jincai Zhao
      8.1 Introduction                             199  (1)
      8.2 Principle of Photosensitization          200  (1)
      8.3 Dye Sensitization                        201  (12)
        8.3.1 Fundamentals of Dye Sensitization    202  (1)
        8.3.1.1 Geometry and Electronic            202  (1)
        Structure of Interface
        8.3.1.2 Excited-State Redox Properties     203  (2)
        of Dyes
        8.3.1.3 Electron Transfer from Dyes to     205  (3)
        TiO2
        8.3.2 Application of Dye Sensitization     208  (1)
        8.3.2.1 Nonregenerative Dye                208  (3)
        Sensitization
        8.3.2.2 Regenerative Dye Sensitization     211  (2)
      8.4 Polymer Sensitization                    213  (1)
        8.4.1 Carbon Nitride Polymer               213  (1)
        8.4.2 Conducting Polymers                  214  (1)
      8.5 Surface-Complex-Mediated Sensitization   214  (4)
        8.5.1 Organic Ligand                       215  (2)
        8.5.2 Inorganic Ligand                     217  (1)
      8.6 Solid Semiconductor/Metal                218  (8)
      Sensitization
        8.6.1 Small-Band-Gap Semiconductor         219  (1)
        8.6.1.1 Basic Concepts                     219  (1)
        8.6.1.2 Category in Terms of Charge        219  (3)
        Transfer Process
        8.6.2 Plasmonic Metal                      222  (1)
        8.6.2.1 Basic Concepts                     222  (2)
        8.6.2.2 Proposed Mechanisms                224  (1)
        8.6.2.3 Critical Parameters                225  (1)
      8.7 Other Strategies to Make Titania         226  (4)
      Visible Light Active
        8.7.1 Band Gap Engineering                 226  (1)
        8.7.1.1 Metal Doping                       226  (1)
        8.7.1.2 Nonmetal Doping                    227  (1)
        8.7.1.3 Codoping                           227  (1)
        8.7.2 Structure/Surface Engineering        228  (2)
      8.8 Conclusions                              230  (11)
        Acknowledgment                             231  (1)
        References                                 231  (10)
    9 Photoelectrocatalysis for Water              241  (30)
    Purification
          Rossano-Amadelli
          Luca Samiolo
      9.1 Introduction                             241  (1)
      9.2 Photoeffects at Semiconductor            242  (3)
      Interfaces
      9.3 Water Depollution at Photoelectrodes     245  (4)
        9.3.1 Morphology and Microstructure        245  (2)
        9.3.2 Effect of Applied Potential          247  (1)
        9.3.3 Effect of pH                         247  (1)
        9.3.4 Effect of Oxygen                     248  (1)
        9.3.5 Electrolyte Composition              249  (1)
      9.4 Photoelectrode Materials                 249  (6)
        9.4.1 Titanium Dioxide                     249  (1)
        9.4.1.1 Cation Doping                      250  (1)
        9.4.1.2 Nonmetal Doping                    250  (1)
        9.4.2 Other Semiconductor                  251  (1)
        Photoelectrodes
        9.4.2.1 Zinc Oxide and Iron Oxide          251  (1)
        9.4.2.2 Tungsten Trioxide                  251  (1)
        9.4.2.3 Bismuth Vanadate                   251  (1)
        9.4.3 Coupled Semiconductors               251  (2)
        9.4.3.1 n--n Heterojunctions               253  (1)
        9.4.3.2 p--n Heterojunctions               254  (1)
      9.5 Electrodes Preparation and Reactors      255  (1)
      9.6 Conclusions                              256  (15)
        References                                 257  (14)
  Part III Effects of Photocatalysis on Natural    271  (40)
  Organic Matter and Bacteria
    10 Photocatalysis of Natural Organic Matter    273  (22)
    in Water: Characterization and Treatment
    Integration
          Sanly Liu
          May Lim
          Rose Amal
      10.1 Introduction                            273  (1)
      10.2 Monitoring Techniques                   274  (7)
        10.2.1 Total Organic Carbon                275  (1)
        10.2.2 UV--vis Spectroscopy                275  (2)
        10.2.3 Fluorescence Spectroscopy           277  (1)
        10.2.4 Molecular Size Fractionation        278  (2)
        10.2.5 Resin Fractionation                 280  (1)
        10.2.6 Infrared Spectroscopy               280  (1)
      10.3 By-products from the Photocatalytic     281  (3)
      Oxidation of NOM and its Resultant
      Disinfection By-Products (DBPs)
      10.4 Hybrid Photocatalysis Technologies      284  (3)
      for the Treatment of NOM
      10.5 Conclusions                             287  (8)
        References                                 289  (6)
    11 Waterborne Escherichia coli Inactivation    295  (16)
    by TiO2 Photoassisted Processes: a Brief
    Overview
          Julian Andres Rengifo-Herrera
          Angela Giovana Rincon
          Cesar Pulgarin
      11.1 Introduction                            295  (1)
      11.2 Physicochemical Aspects Affecting       296  (3)
      the Photocatalytic E. coli Inactivation
        11.2.1 Effect of Bulk Physicochemical      296  (1)
        Parameters
        11.2.1.1 Effect of TiO2 Concentration      296  (1)
        and Light Intensity
        11.2.1.2 Simultaneous Presence of          297  (1)
        Anions and Organic Matter
        11.2.1.3 pH Influence                      298  (1)
        11.2.1.4 Oxygen Concentration              298  (1)
        11.2.2 Physicochemical Characteristics     299  (1)
        of TiO2
      11.3 Using of N-Doped TiO2 in                299  (3)
      Photocatalytic Inactivation of Waterborne
      Microorganisms
      11.4 Biological Aspects                      302  (1)
        11.4.1 Initial Bacterial Concentration     302  (1)
        11.4.2 Physiological State of Bacteria     302  (1)
      11.5 Proposed Mechanisms Suggested for       303  (1)
      Bacteria Abatement by Heterogeneous TiO2
      Photocatalysis
        11.5.1 Effect of UV-A Light Alone and      303  (1)
        TiO2 in the Dark
        11.5.2 Cell Inactivation by Irradiated     304  (1)
        TiO2 Nanoparticles
      11.6 Conclusion                              304  (7)
        References                                 305  (6)
  Part IV Modeling. Reactors. Pilot plants         311  (88)
    12 Photocatalytic Treatment of Water:          313  (22)
    Irradiance Influences
          David Ollis
      12.1 Introduction                            313  (1)
        12.1.1 Chapter Topics                      313  (1)
        12.1.2 Photon Utilization Efficiency       313  (1)
      12.2 Reaction Order in Irradiance:           314  (1)
      Influence of Electron -- Hole
      Recombination and the High Irradiance
      Penalty
      12.3 Langmuir--Hinshelwood (LH) Kinetic      315  (2)
      Form: Equilibrated Adsorption
      12.4 Pseudo-Steady-State Analysis:           317  (4)
      Nonequilibrated Adsorption
      12.5 Mass Transfer and Diffusion             321  (2)
      Influences at Steady Conditions
      12.6 Controlled Periodic Illumination:       323  (1)
      Attempt to Beat Recombination
      12.7 Solar-Driven Photocatalysis: Nearly     324  (2)
      Constant nUV Irradiance
      12.8 Mechanism of Hydroxyl Radical           326  (1)
      Attack: Same Irradiance Dependence
      12.9 Simultaneous Homogeneous and            327  (1)
      Heterogeneous Photochemistry
      12.10 Dye-Photosensitized Auto-Oxidation     328  (1)
      12.11 Interplay between Fluid Residence      329  (2)
      Times and Irradiance Profiles
        12.11.1 Batch Reactors                     329  (1)
        12.11.2 Flow Reactors                      329  (2)
      12.12 Quantum Yield, Photonic Efficiency,    331  (1)
      and Electrical Energy per Order
      12.13 Conclusions                            332  (3)
        References                                 332  (3)
    13 A Methodology for Modeling Slurry           335  (26)
    Photocatalytic Reactors for Degradation of
    an Organic Pollutant in Water
          Orlando M. Alfano
          Alberto E. Cassano
          Rodolfo J. Brandi
          Marlia L. Satuf
      13.1 Introduction and Scope                  335  (2)
      13.2 Evaluation of the Optical Properties    337  (5)
      of Aqueous TiO2 Suspensions
        13.2.1 Spectrophotometric Measurements     338  (1)
        of TiO2 Suspensions
        13.2.2 Radiation Field in the              339  (2)
        Spectrophotometer Sample Cell
        13.2.3 Parameter Estimation                341  (1)
      13.3 Radiation Model                         342  (4)
        13.3.1 Experimental Set Up and Procedure   343  (1)
        13.3.2 Radiation Field Inside the          344  (2)
        Photoreactor
      13.4 Quantum Efficiencies of                 346  (2)
      4-Chlorophenol Photocatalytic Degradation
        13.4.1 Calculation of the Quantum          346  (1)
        Efficiency
        13.4.2 Experimental Results                347  (1)
      13.5 Kinetic Modeling of the Pollutant       348  (4)
      Photocatalytic Degradation
        13.5.1 Mass Balances                       348  (1)
        13.5.2 Kinetic Model                       349  (1)
        13.5.3 Kinetic Parameters Estimation       350  (2)
      13.6 Bench-Scale Slurry Photocatalytic       352  (4)
      Reactor for Degradation of 4-Chlorophenol
        13.6.1 Experiments                         352  (1)
        13.6.2 Reactor Model                       352  (1)
        13.6.2.1 Radiation Model                   352  (2)
        13.6.2.2 Reaction Rates                    354  (1)
        13.6.2.3 Mass Balances in the Tank and     354  (1)
        Reactor
        13.6.3 Results                             355  (1)
      13.7 Conclusions                             356  (5)
        Acknowledgments                            357  (1)
        References                                 357  (4)
    14 Design and Optimization of                  361  (16)
    Photocatalytic Water Purification Reactors
          Tsuyoshi Ochiai
          Akira Fujishima
      14.1 Introduction                            361  (2)
        14.1.1 Market Transition of Industries     361  (1)
        Related to Photocatalysis
        14.1.2 Historical Overview                 361  (2)
      14.2 Catalyst Immobilization Strategy        363  (3)
        14.2.1 Aqueous Suspension                  363  (2)
        14.2.2 Immobilization of TiO2 Particles    365  (1)
        onto Solid Supports
      14.3 Synergistic Effects of                  366  (3)
      Photocatalysis and Other Methods
        14.3.1 Deposition of Metallic              366  (1)
        Nanoparticles onto TiO2 Surface for
        Disinfection
        14.3.2 Combination with Advanced           367  (2)
        Oxidation Processes (AOPs)
      14.4 Effective Design of Photocatalytic      369  (3)
      Reactor System
        14.4.1 Two Main Strategies for the         369  (2)
        Effective Reactors
        14.4.2 Design of Total System              371  (1)
      14.5 Future Directions and Concluding        372  (5)
      Remarks
        Acknowledgments                            373  (1)
        References                                 373  (4)
    15 Solar Photocatalytic Pilot Plants:          377  (22)
    Commercially Available Reactors
          Sixto Malato
          Pilar Fernandez-Ibanez
          Maneil Ignacio Maldonado
          Isabel Oller
          Maria Inmaculada Polo-Lopez
      15.1 Introduction                            377  (2)
      15.2 Compound Parabolic Concentrators        379  (3)
      15.3 Technical Issues: Reflective Surface    382  (4)
      and Photoreactor
      15.4 Suspended or Supported Photocatalyst    386  (2)
      15.5 Solar Photocatalytic Treatment Plants   388  (2)
      15.6 Specific Issues Related with Solar      390  (4)
      Photocatalytic Disinfection
      15.7 Conclusions                             394  (5)
        Acknowledgments                            395  (1)
        References                                 395  (4)
Index                                              399