Comparative Study on Electrochemical Treatment of Arsenite: Effects of Process Parameters, Sludge Characterization and Kinetics

摘要

This study involves the application of electrocoagulation process to remove arsenite from simulated groundwater using steel,aluminium, platinum and glassy carbon in a 2-L batch reactor setup. It was observed that arsenite was initially oxidized toarsenate. In the case of glassy carbon and platinum electrodes, arsenate build-up was found in the solution due to the lack offloc formation. However, in the case of steel and aluminium electrodes, the flocs generated effectively adsorbed the arsenateproduced. Parametric studies reveal the highest removal efficiency of arsenite at low pH, high current and low concentration,with the optimum removal according to surface response methodology achieved at pH 4, 1.2 A and 10 ppm. Electricalenergy consumption evaluation shows that operating at the optimum conditions, 653.33 kWh/kg is required to achieve WHOlimit from an initial arsenite concentration of 10 ppm. Kinetic studies indicate that the rate is best described by first-ordermodel. The sludges obtained after the electrocoagulation process using the steel and aluminium electrodes further revealthe adsorption of arsenic species onto the metal hydroxide surfaces.