Electrochemical removal of zinc and nickel ions from wastewater using porous electrodes

Abstract

Simulated wastewater containing Ni++ and Zn++ was treated using an electrochemical cell. Porous aluminum cathode and porous stainless steel anode were used in a flow-through configuration. For porous catholdes, both aluminium foam and corrugated aluminum plates having perforations were used. To study the effects of applied voltage and volumetric liquid flux on the removal of Ni++ and Zn++, the electrochemical cell was operated for 48 hours at different applied voltages of 5, 10, 15, 20 and 25 V, and at different volumetric liquid fluxes both in the laminar (0.00471 and 0.00943 m³.m-².s-¹) and turbulent regimes (0.01414, 0.01886 and 0.02357 m³.m-².s-¹). For the maximum removal of both nickel and zinc ions, the optimum applied voltage and volumetric liquid flux were found to be 12 V and 0.02357 m³.m-².s-¹, respectively; under these operating conditions, the concentrations of Ni++ and Zn++ in the simulated wastewater were reduced by 85.5% and 98%, respectively. Operating beyond an applied voltage of 12 V, the removal of Zn++ was slightly improved and achieved a maximum value of 99.05% at 25 V; however, an opposite trend was observed in case of Ni++ removal, which finally decreased to 56% at 25 V., because of the excessive precipitation of Ni++ as nickel hydoroxide.