Performance Evaluation of Electrocoagulation Process for Removal of Chromium (VI) from Synthetic Chromium Solutions Using Iron and Aluminum Electrodes

The performance of electrocoagulation with iron and aluminum sacrificial anode for removal of Cr(VI) was investigated. Several working parameters, such as pollutant concentration, pH, electrical potential, COD, turbidity, and contact time were studied in an attempt to achieve a higher removal capacity. Solutions of varying chromium concentrations (5-50-500 ppm) were prepared. To follow the progress of the treatment, samples of 25 ml were taken at 20 min intervals for up to 1 h and then filtered (0.45 μ) to eliminate sludge formed during electrolysis. The pH of the initial solution was also varied to study their effects on the chromium removal efficiency. Results obtained with synthetic wastewater revealed that the most effective removal capacities of the studied metals could be achieved when the pH was kept at 3. In addition, the increase of electrical potential, in the range of 20-40 V, enhanced the treatment rate without affecting the charge loading required to reduce metal ion concentrations under admissible legal levels. The process was successfully applied to the treatment of electroplating wastewater where an effective reduction of Cr(VI) concentration under legal limits was obtained just after 20-60 min. The results of this study showed that the removal efficiency of chromium with iron electrodes is higher compared to aluminum electrodes. Also, it can be concluded that the electrocoagulation process has the potential to be utilized for cost-effective removal of heavy metals from water and wastewater. Key words: Electrocoagulation, chromium removal, aluminum electrodes, iron electrode