Abstract
The photocatalyzed and ozonated degradation of a widely used pesticide, chlorothalonil was studied using Ru loaded on titania as photocatalyst under visible light. The Ru/TiO2 photocatalysts with metal loadings 0, 0.25, 0.50, and 1 wt% on TiO2 were prepared by deposition–precipitation method and characterized by X-ray diffraction, UV-DRS, Brunauer–Emmett–Teller, transmission electron microscopy, SEM–EDX, FT-IR, and ICP analyses. Photocatalyzed ozonation with 1% Ru/TiO2 yielded 100% degradation and mineralization of chlorothalonil in 2 h under basic pH conditions. The extent of degradation of chlorothalonil pesticide and its mineralization were confirmed by GC–MS. For 10 mg/L of chlorothalonil, 0.1 g/L of catalyst was found to be the optimum for effective mineralization. Results show that photocatalyzed ozonation of chlorothalonil with Ru/TiO2 catalyst is a very practical means for its mineralization. The catalyst is fully recoverable and reusable multiple times with no loss of activity.
Acknowledgments
The authors are indebted to the National Research Foundation, South Africa, for financial support and University of KwaZulu-Natal, Durban, South Africa for the research facilities.