Electrotreatment of industrial copper plating rinse effluent using mild steel and aluminum electrodes

BACKGROUND: Heavy metals from aqueous streams can be removed effectively using electrochemical techniques. Although both mild steel (MS) and aluminum (Al) electrodes have long been considered for the treatment of different waste‐waters, unfortunately the reported optimum treatment time, current density, pH and background electrolyte concentration vary greatly. In this work, an electrochemical technique was used for the removal of Cu from electroplating rinse water collected from a local plating industry using MS and Al as electrode materials. RESULTS: Removal of Cu during electrotreatment is due to the combined effect of hydroxide precipitation and electrodeposition. The discharge limit of Cu (3 mg L^?1) was achieved with both the electrodes and electrode arrangements. Both MS and Al electrodes showed similar performance for removing copper, however, a lower increase in pH was observed with the MS electrode under identical experimental conditions. NaCl added to increase the solution conductivity decreases Cu removal and inhibits oxide layer formation during electrotreatment. The effluent contains about 6.8 mg L^?1 Zn and its discharge limit (4 mg L^?1) was achieved within the first 10 min of treatment. CONCLUSIONS: Results obtained from experiments demonstrate that the stipulated limit of both Cu and Zn can be achieved during treatment of industrial plating effluent using MS and Al as electrode materials, depending on current density and treatment time. Copyright © 2009 Society of Chemical Industry