Degradation of a Toxic Mixture of the Pesticides Carbofuran and Iprodione by UV/H2O2: Evaluation of Parameters and Implications of the Degradation Pathways on the Synergistic Effects

Abstract

The degradation of two pesticides, carbofuran (CBF) and ioprodine (IPR), was studied by the photolytic decomposition of hydrogen peroxide (UV/H2O2). The influence of two experimental parameters, H2O2 concentration and initial pH, as well as their interactions, was investigated. Optimization was carried out where experimental parameters were determined for the treatment of each pesticide. Both pesticides were totally eliminated by UV/H2O2 system under optimal conditions. However, significant differences were found: CBF degradation was influenced by both parameters and their interactions, while IPR degradation was not statistically affected by initial pH. Interestingly, analysis of degradation pathways showed a major influence of photolysis process and oxidation due to hydrogen peroxide for the CBF degradation, while the synergistic combination between both of them played the most relevant role during IPR degradation. A mixture of both pesticides was also submitted to UV/H2O2 action in which a lower rate was observed for IPR elimination while CBF was not affected. A 90 % of chemical oxygen demand (COD) was removed and 75 % of mineralization was achieved after the treatment of the mixture. Almost 92 % of the toxicity was eliminated making this technique a promising process to treat toxic mixtures of these pesticides.