Electrochemical Removal of Zinc and Nickel Ions from Wastewater Using Flat Plate Electrodes

Simulated wastewater containing 20ppm of Zn++, 20ppm of Ni++ was treated using an electrochemical technique. This synthetic wastewater was used to simulate the wastewater from metal finishing industries. A rectangular bath integrated with an electrochemical cell consisting of flat plate electrodes (the stainless steel anode and aluminum cathode) was used in the treatment. Potassium sulfate was used as a supporting electrolyte to enhance the removal of Zn++ and Ni++. The effects of volumetric liquid flux, pH and electrode surface area on Zn++ and Ni++ removal were investigated. All experiments were performed at 25ºC and at an applied voltage of 4V. When volumetric flux was raised from 0.0092 to 0.0277m³.m-².s-¹, an increasing trend of the Zn++ and Ni++ removal was observed. The maximum metal removal was observed at a volumeteric liquid flux of 0.0231m³.m-².s-¹. Zn++ and Ni++ were removed by 80% and 34%, respectively, after 48 hours of electrochemical treatment. Moreover, an increase in the removal of Zn++ and Ni++ was observed when the pH was varied from 3.5 to 6.5. The maximum removal of Zn++ and Ni++, 97% and 62%, respectively, occurred at a volumetric liquid flux of 0.0231m³.m-².s-¹ and a pH of 6.5. The experimental values showed a similar increasing trend in the removal of Zn++ and Ni++, when the electrode surface area was increased from 0.024m² to 0.048m²; the removal of Zn++ and Ni++ improved by 14% and 12%, respectively. However, there was no major change in the removal of Zn++ and Ni++ between flat plate and corrugated plate electrodes.