Electrochemical oxidation of dichlorvos on SnO2Sb2O5 electrodes

• Electrochemical oxidation of dichlorvos followed Langmuir–Hinshelwood kinetics.
• Dichlorvos electro-oxidation kinetics gives the fastest overall rate constants.
• Rate limiting step for electro-oxidation is the same as for the mineralization.

The effects of electrode potential and the initial concentration of 2,2-dichlorovinyl dimethyl phosphate (dichlorvos, DDVP) on its oxidation/mineralization reaction kinetics, using an electrochemical oxidation system based on SnO2Sb2O5 anodes, have been studied. Electrochemical degradation followed the Langmuir–Hinshelwood mechanism, with adsorption equilibrium constant K = 0.082 L mg−1 of dichlorvos on the electrode material surface, and reaction rate constant k = 0.021 mg L−1 s−1 of the organic compound-electrocatalyst adduct. Chemical oxygen demand and CO2 measurements in neutral media suggest that the rate limiting step for mineralization is the same as for the electrochemical oxidation. The results show that the electrochemical mineralization of dichlorvos was readily possible at potentials more positive than 2.5 V vs. SCE, with lower reaction half-lives than obtained with other advanced oxidation process. The fastest overall degradation rate constants were obtained at limiting low concentrations of dichlorvos in aqueous solution, kobs = kK = 0.0017 s−1.

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