Studies on the Removal of Arsenate by Electrochemical Coagulation Using Aluminum Alloy Anode

The removal of arsenate from aqueous solution was carried out by electrochemical coagulation using aluminum alloy as anode and stainless steel as cathode. Various operating parameters on the removal efficiency of arsenate were investigated, such as initial arsenate ion concentration, initial pH, current density, and temperature. Effect of coexisting anions such as silicate, fluoride, phosphate, and carbonate were studied on the removal efficiency of arsenate. The optimum removal efficiency of 98.4% was achieved at a current density of 0.2 A/dm(2) at a pH of 7.0. The experimental data were tested against different adsorption isotherm models for describing the electrochemical coagulation process. The adsorption of arsenate preferably fitting the Langmuir adsorption isotherm suggests monolayer coverage of adsorbed molecules. First and second order rate equations were applied to study adsorption kinetics. The adsorption process follows second order kinetics model with good correlation. Temperature studies showed that adsorption was endothermic and spontaneous in nature.