Kinetics of photocatalytic degradation of trichloroethylene in aqueous colloidal solutions of TiO2 and WO3 nanoparticles

Abstract

Abstract Kinetic studies on the photocatalytic degradation of trichloroethylene (TCE) were performed in TiO 2 or WO 3 aqueous sol which consisted of anatase nanocrystalline TiO 2 of ca. 3.9 nm or WO 3 spherical particles of ca. 17.6 nm. Photocatalytic activity of TiO 2 colloid is higher than that of WO 3 by a factor of 2.1. Kinetic analyses for both sols give a similar rate law containing γ value which represents a ratio of the reaction rate of the photogenerated electrons with O 2 against the total disappearance rate of the photogenerated electrons. Reaction temperature did not affect the TiO 2 photocatalysis whereas higher temperature increased the oxidation rate of TCE in the WO 3 sol. Such a difference in the temperature effect was explained in terms of the γ values. The photocatalytic degradation of TCE was enhanced by mixing the WO 3 and the TiO 2 sol and the best performance was obtained by using the mixed sol with WO 3 :TiO 2 molar ratio of 1:2. In the mixed sol, the similar temperature dependence as in the WO 3 sol was obtained. Reaction mechanism and the rate law are proposed to account for the obtained kinetic data.