ABSTRACT
Advanced oxidation processes (AOPs) are a group of related processes or technologies that lead to the generation of radical oxygen species, which result in the oxidative degradation of pollutants in water. Heterogeneous or semiconductor photocatalysis is an AOP wherein the photoexcitation of the semiconductor material results in the production of radical oxygen species that can degrade organic pollutants. Inorganic substances present in water can undergo oxidation or reduction to less harmful analogs. AOPs present alternative and complementary approaches to the treatment of water containing problematic pollutants that may not be effectively removed by conventional treatment methods. For example, pesticides, by their very nature, are designed to be stable, persistent, toxic, and active at low concentrations and, because of their widespread dispersion in the environment, they will inevitably ‹nd their way into water sources. AOPs may be employed as a speci‹c measure to deal with persistent organic chemicals such as pesticides. Furthermore, there is evidence that conventional disinfection methods are
CONTENTS
3.1 Introduction .................................................................................................. 37 3.2 Semiconductor Photocatalysis ...................................................................38 3.3 Selection of Photocatalyst ........................................................................... 39 3.4 Reaction Kinetics .........................................................................................42 3.5 Pollutants Degraded by Photocatalysis ....................................................43 3.6 Reactor Engineering .................................................................................... 49 3.7 VLA Photocatalytic Materials ....................................................................53 3.8 Issues to be Addressed ................................................................................55 3.9 Conclusions ................................................................................................... 57 References ...............................................................................................................58
not effective against certain species of pathogenic microoganisms and AOPs may present an alternative or complementary approach to dealing with disinfection-resistant strains. Semiconductor photocatalysis is an advanced oxidation technology, which has been widely studied for use in water and wastewater treatment.
