Effect of some operational parameters on the arsenic removal by electrocoagulation using aluminum electrodes

Abstract

In this study, removal of arsenic by electrocoagulation (EC) with aluminum electrodes was investigated. The experiments were carried out in a batch reactor. Effects of some operational parameters such as initial pH, electrolysis time, current density, initial arsenic concentration, supporting electrolyte type and stirring speed on the arsenic removal by EC were investigated in experiments. The highest removal efficiencies were observed at initial pH 4. Arsenic removal efficiency reached to 98 % with increasing current density from 0.18 to 4.28 mA cm-2, but energy consumption increased in this interval, too. Adding supporting electrolyte had not significant effects on the arsenic removal but it decreased energy consumption of system. Stirring speed affected arsenic removal efficiency and the best stirring speed was 150 rpm. Under the optimum conditions of an initial pH of 4, current density of 0.54 mA cm-2, stirring speed of 150 rpm, electrolysis time of 60 minutes, arsenic was removed from aqueous solutions including arsenic concentration of 50 mg L-1, at a rate of 85 %. Electrical energy consumption in the above conditions for the arsenic removal was calculated as 230 kWh kg-1.