Electrocatalytic performance of PbO2 films in the degradation of dimethoate insecticide

Abstract

This study was performed to find the best experimental conditions for the electrochemical removal of the insecticide dimethoate (C₅H₁₂NO₃PS₂) from aqueous solutions using a lead dioxide niobium anode. The process was studied under galvanostatic polarisation mode. The influence of applied current density (10–50 mA·cm–2), initial chemical oxygen demand COD0 (100–550 mg·ℓ^–1), temperature (30–70°C) and pH (3–11) on COD and instantaneous current efficiency (ICE) was studied. The results showed that almost 90% of COD removal was achieved under optimal experimental conditions, indicating that electrochemical oxidation on a PbO2 anode is a suitable method for treatment of water polluted with dimethoate. It was found that the decay of COD generally followed a pseudo first-order kinetic and the oxidation rate was favoured by increasing the applied current density, temperature, pH and initial COD. The greatest COD removal (90%) was obtained when using an applied current density of 50 mA·cm^–2, COD0 = 320 mg·ℓ^–1, pH = 11, T = 70°C and electrolysis time = 8 h.

Keywords: Electrochemical degradation; hydroxyl radicals; organic pollutants; lead dioxide; wastewater