Copper(II), Chromium(VI) and Nickel(II) Removal From Metal Plating Effluent by Electrocoagulation

Abstract

The present study is on the removal of Cu(II), Cr(VI), Ni(II) from metal plating wastewater by electrocoagulation (EC) in a batch mode using aluminum (Al), iron (Fe) and stainless steel (St) electrodes. The various parameters like pH (3, 5, 7, 9), current density (30, 70, 90 A/m2), electrolyte (NaCl) concentration (800, 1200 mg/L) and operation time of EC (2.5-60 min) on the removal efficiency of metals were studied. The needed operation time of EC to simultaneously provide %100 Cu, %100 Cr and 100% Ni removal at a pH of 2.42 (original) and a current density of 50 A/m2 was 30 min. For Fe-Fe, Fe-Al pairs, 40 min. for Fe-St, Al-Al, Al-Fe, and 60 min. for Al-St, respectively. By comparing all electrode pairs with each other with respect to desired operating, Fe-St electrode pair was chosen as the optimum for the subsequent of experiments. When only Fe-St pair was used, the removal efficiencies of 100% for all metals were determined at a pH of 9, a current density of 90 A/m2 and a NaCl addition of 800 mg/L .The characteristics of the sludge produced after 60 min. EC were analysed by X-ray diffractometer (XRD), and SVI values for electrode pairs were calculated. The XRD analysis of the sludge produced during EC revealed that Magnetite(Fe<inf>3</inf>O<inf>4</inf>), Gibbsite(Al(OH)<inf>3</inf>) and Kaolinite(Al<inf>4</inf>(Si<inf>4</inf>O<inf>10</inf>)(OH)<inf>8</inf>) were the main by-product formed after EC. © 2014 The Authors. Published by ESG.