THE EFFECT OF PH AND CURRENT DENSITY IN THE REMOVAL OF ALUMINUM COBALT, CHROMIUM, AND ZINC FROM METAL PROCESSING WASTEWATER BY ELECTROCOAGULATION METHOD

Abstract

In this study, the effects of initial pH (3, 5, 7, 9) and current density (25, 50, 75, 100, 125, 150, 175, 200 A/m2) on the removal of Al3+, Co2+, Cr6+ and Zn2+ions from metal processing wastewater by electrocoagulation method were examined. Iron and stainless steel electrodes were used as anode and cathode materials. All of the removal efficiencies were insignificant at the initial pH value of 1.32. As the initial pH values were increased the removal efficiencies increased in all stages of the experiments. With increasing the pH from 3 to 9, removal efficiencies increased from 67.4% to 99.2% for Al, from 18.1% to 99.7% for Co, and from 36.6% to 99.9% for Zn, while removal efficiencies for Cr were over 99% for each pH. Although the inital concentration of Co was relatively low, it was only removed with over 99% efficiency at long electrocoagulation times or at relatively high final pH values. A similar trend was determined for Zn, but this case was explained by a relatively high concentration of Zn. While the maximum removal efficiency was achieved with a current density of 50 A/m2 for Cr, the efficiency increases were more obvious with increasing current density for Al, Co, and Zn.

Keywords

• Electrocoagulation
• pH
• Current Density
• Metal Processing

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