Solar photo-Fenton treatment of carbofuran: Analysis of mineralization, toxicity, and organic by-products

Abstract

The degradation of the pesticide carbofuran (CBF) using solar photo-Fenton treatment, at both the laboratory and the pilot scale, was evaluated. At the laboratory scale, in a suntest reactor, the Fe²⁺ concentration and H₂O₂ concentration were evaluated and optimized using the surface response methodology and the Pareto diagram. Under optimal conditions experiments were performed to evaluate the evolution of the substrate removal, oxidation, subsequent mineralization, toxicity and the formation of chloride ions during the treatment. The analysis and evolution of five CBF by-products as well as several control and reactivity tests at the density functional theory level were used to depict a general scheme of the main degradation pathway of CBF via the photo-Fenton system. Finally, at the pilot scale, a sample of the commercial CBF product Furadan was eliminated after 420 min by the photo-Fenton system using direct sunlight. Under these conditions, after 900 min 89% of toxicity (1/E₅₀ on Vibrio fischeri bacteria), 97% of chemical oxygen demand, and 90% of dissolved organic carbon were removed.

Keywords:

• Advanced oxidation processes
• carbofuran
• DFT study
• Furadan
• pesticides
• solar photo-Fenton

Acknowledgements

The authors wish to acknowledge to the Grupo Diagnóstico y Control de la Contaminación (GDCON) likewise to the sustainability grant of the Vicerrectoría de Investigaciones of the Universidad de Antioquia for the financial support.