ABSTRACT

Diuron contamination of water is a general concern because of the pesticide’s toxicity and persistence in the environment. Thus, TiO₂-facilitated remediation of water contaminated with 1 mg·L^–1 diuron was studied using a solar simulator, and under various pH conditions and photocatalyst concentrations, and with the addition of electron acceptors besides molecular oxygen. The effect of a combined TiO₂/photo-Fenton process was also investigated. Diuron degradation rates were found to be strongly affected by all of the above parameters. Degradation rates increased with increases in pH from 5–9, and decreased when the pH was increased to 11. The degradation rate of diuron increased with increases in TiO₂ photocatalyst concentrations, up to a maximum concentration of 1 g·L^–1. The decrease in total organic carbon due to diuron mineralization was clearly higher when the combination of TiO₂ and peroxydisulfate (10 mM) was used, when compared that obtained with TiO₂ alone and TiO₂ with hydrogen peroxide (20 mM). The combined solar TiO₂/photo-Fenton process was the most effective method for both degradation and mineralization of diuron in water. Eight kinds of intermediate products from diuron degradation were identified by GC-MS analysis.