Photocatalytic degradation of metoxuron in aqueous suspensions ofTiO2. Analytical and kinetic studies
The photocatalytic degradation of metoxuron [3-(3-chloro-4-methoxyphenyl)-1,1-dimethylurea] in aqueous suspensions ofTiO2was 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 P25TiO2was found to exhibit a higher photocatalytic activity than MillenniumTiO2in spite of a generally smaller specific surface area. Within the MillenniumTiO2series, the photocatalytic efficiency increased with the specific surface area.