Reaction Mechanisms for TiO2 Powder Photocatalyzed Systems

Summary

An overview of 10 apparently different, although in some cases closely related, popular photocatalytic reaction mechanisms for TiO₂ powder aqueous dispersions is given. The key reaction processes associated with each mechanism are identified and discussed, and the overall rate expression is reported. Five of the mechanisms are tested using datasets comprising initial reaction rate versus organic pollutant concentration, [P] and incident irradiance, ρ, data that have been reported previously for TiO₂, where P was phenol, 4‐chlorophenol, and formic acid. The best of those tested in terms of simplicity, usefulness, and versatility is the disrupted adsorption kinetic model, which is described in detail. The need for more datasets with which to test the kinetic models, in which the dependence of rate upon pollutant concentration and irradiance, is discussed.