On-line version ISSN 0378-4738
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, COD = 320 mg.l-1, pH = 11, T = 70°C and electrolysis time = 8 h.
Keywords : Electrochemical degradation; hydroxyl radicals; organic pollutants; lead dioxide; wastewater.