Conclusions
The photocatalytic degradation of diuron in aqueous solution was investigated by platinized TiO2 catalyst. Platinization of TiO2 photocatalyst was found to increase the photocatalytic activity for the degradation of diuron. The degradation rate was strongly affected by Pt doping concentration. The optimum doping Pt concentration found in this study was 0.2 wt.%. Under the optimum conditions, diuron could achieve complete degradation after 20 min. The first-order rate constant for diuron degradation by Pt–TiO2 was ca. 4 times higher than P-25 TiO2. In addition, the photocatalytic activity of 0.2 wt.% Pt–TiO2 was higher than that of P-25 TiO2 both under visible light and UV irradiation.
The disappearance of TOC was observed during the photocatalytic process and the remaining TOC achieved 0.14 mgC L−1 after 8 h (97% mineralization). The formations of chloride, ammonium and nitrate ions were also observed. Therefore, we could reach the complete mineralization of the starting compound. Furthermore, we identified four kinds of intermediate products of diuron during the photocatalytic process. The degradation pathway of diuron was proposed based on the identified by-products under a given set of reaction conditions.
The advantages of Pt–TiO2 photocatalytic process as an oxidative treatment are rapid degradation and simple handling. Therefore, this photocatalytic reaction would be applied to wastewater treatment works as a new developing methodology for reducing levels of other pesticides and endocrine disrupting chemicals.