Photocatalyzed ozonation: effective degradation and mineralization of pesticide, chlorothalonil

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.

Keywords:

• Photocatalyst
• Ozonation
• Chlorothalonil
• Ru–TiO₂
• Deposition–precipitation method
• Mineralization

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.