Current density dependent removal of aqueous Cr(VI) by electrocoagulation

Abstract

Electrocoagulation (EC) is a proven green technology for the remediation of potentially toxic metalloids and metal ions contaminated water and waste water. The EC performance was carried out on a laboratory scale batch mode reactor using Al as anode and cathode for the removal of 5 ppm of Cr(VI) in synthetic water prepared with 150 ppm of Ca2+, 50 ppm of Mg2+ and 5 ppm of F− ions. The results showed that the removal efficiency of Cr(VI) increases with increasing both electrocoagulation time and the current density. At current densities, 4 mA/cm2, 2 mA/cm2 and 1 mA/cm2, removal efficiencies were 98%, 93% and 48% respectively after 140 minutes at initial pH of 6.0. Energy consumption of EC process was found to be 6.57 kWh/m3, 1.84 kW h/m3, and 0.56 kW h/m3 in the same order of decrease in current densities. The EC process gives promising results towards the removal of Cr(VI) at a low consumption of energy, making the process attainable and possible to scale up.