Anodic oxidation of chlorpyrifos in aqueous solution at lead dioxide electrodes

The aim of this work is the use of electrochemical process for the total mineralization of water contaminated with organophosphorus pesticides like chlorpyrifos. This pesticide is widely used both for agricultural pest control and in households as a termiticide. The process was studied under galvanostatic polarization mode using Nb/PbO2 anodes and graphite carbon bar as cathode. The kinetic of organic matter decay and the mineralization efficiency were evaluated by means of the chemical oxygen demand (COD) measurement. The influence of the experimental parameters such as the initial concentration of chlorpyrifos, the apparent current density and the temperature, on the electrochemical process performance was investigated. The experimental results showed that COD removal always follows a pseudo-second-order kinetics. The degradation rate increased significantly with increasing the apparent current density and temperature. However, it decreased with the increase of the initial pollutant concentrations. The best COD removal (76%) was obtained when using an apparent density of 50 mA cm−2, initial COD = 450 mg O2 L−1 and at 70 °C in 10 h electrolysis time.