Photocatalytic degradation of metoxuron in aqueous suspensions of TiO₂. Analytical and kinetic studies

Abstract

The photocatalytic degradation of metoxuron [3‐(3‐chloro‐4‐methoxyphenyl)‐1,1‐dimethylurea] in aqueous suspensions of TiO 2 was investigated. Several intermediate photoproducts were identified using NMR and MS techniques. Oxidation or removal of the methyl of terminal nitrogen and ring hydroxylation were found to occur. 2‐Propanol was shown to decrease the rate of photocatalytic degradation, inhibiting partly ring hydroxylation and completely reactions on terminal nitrogen. In contrast, basification of the suspensions accelerated the degradation significantly. Degussa P25 TiO 2 was found to exhibit a higher photocatalytic activity than Millennium TiO 2 in spite of a generally smaller specific surface area. Within the Millennium TiO 2 series, the photocatalytic efficiency increased with the specific surface area.