Environmental Engineering Reference
In-Depth Information
25
Modiied TiO
2
-Based Photocatalytic Systems for the
Removal o
f Emerging Contaminants from Water
Ligy Philip, Arya Vijayanandan, and Jaganathan Senthilnathan
Department of Civil Engineering, Indian Institute of Technology (IIT) Madras, Chennai, India
CONTENTS
25.1 Introduction ...................................................................................................................... 480
25.2 Emerging Contaminants ................................................................................................. 480
25.3 Treatment Technologies .................................................................................................. 482
25.3.1 Activated Sludge Process .................................................................................. 482
25.3.2 Membrane Bioreactors ...................................................................................... 482
25.3.3 Membrane Processes ......................................................................................... 482
25.3.4 Activated Carbon Adsorption .......................................................................... 482
25.3.5 Chlorination ........................................................................................................ 483
25.4 Advanced Oxidation Processes ..................................................................................... 483
25.4.1 Fenton's Oxidation Process ............................................................................... 484
25.4.2 Photolysis ............................................................................................................ 484
25.4.3 Ozonation ............................................................................................................ 484
25.4.4 Electrochemical Oxidation ............................................................................... 484
25.4.5 Sonolysis .............................................................................................................. 485
25.4.6 Photocatalysis ..................................................................................................... 485
25.4.7 Heterogeneous Photocatalysis ......................................................................... 485
25.5 TiO
2
as a Photocatalyst .................................................................................................... 485
25.6
Factors Affecting the UV/TiO
2
Process ........................................................................ 487
25.6.1 Substrate Concentration .................................................................................... 487
25.6.2 Light Intensity .................................................................................................... 487
25.6.3 Photocatalyst Dosage ........................................................................................ 488
25.6.4 Solution pH ......................................................................................................... 488
25.6.5 Temperature ........................................................................................................ 488
25.6.6
Electron Scavenger ............................................................................................. 488
25.6.7
Photocatalyst Deactivation ............................................................................... 489
25.7
Modiied TiO
2
for Improved Photocatalytic Activity under Visible Light .............. 489
25.7.1
Use of Organic Dye as Photosensitizer........................................................... 489
25.7.2
Doping with Metal Ions .................................................................................... 489
25.7.3
Doping with Nonmetallic Elements ............................................................... 490
25.7.4
Coupling with Semiconductors ....................................................................... 491
25.7.5
Metal Ion Implantation ..................................................................................... 491
25.7.6
Use of Photosensitizers ..................................................................................... 492
25.8
Photoreactors Used in Water Treatment ....................................................................... 492
25.8.1
Practical Applications of Solar Photocatalysis ............................................... 492
479
