Ozone-driven photocatalyzed degradation and mineralization of pesticide, Triclopyr by Au/TiO₂

Abstract

Triclopyr is a widely used pesticide which is non-biodegradable and enters aquatic systems. The ozone facilitated photocatalyzed degradation and mineralization of Triclopyr using Au-loaded titania as heterogeneous catalyst is reported. The oxidative degradation activity of the hazardous pesticide was investigated at pH 7.8 under varied reaction conditions, including in presence and absence of ozone, titania alone, in presence and absence of light and with different loadings of Au on support. Photocatalysis with 2% Au/TiO₂ in the presence of ozone yielded 100% degradation of Triclopyr in 2 h. The extent of degradation of pesticide and its mineralization were confirmed by GC-MS. For 10 mg/L of Triclopyr, 0.1 g/L of catalyst was found to be the optimum for mineralization. Results show that photocatalyzed ozonation with Au/TiO₂ as catalyst is a very effective for its removal. No leaching of Au was observed in triplicate runs. Catalyst was fully recoverable and reusable with no loss of activity.

Keywords:

• Photocatalyzed ozonation
• Triclopyr
• Au-TiO₂
• deposition-precipitation method
• mineralization

Acknowledgments

The authors are grateful to the University of KwaZulu-Natal for the research facilities. C. Vasam is currently at Satavahana University, Karim Nagar, India.

Funding

The authors are grateful to the National Research Foundation of South Africa for financial support.