Recovery of copper from electroplating sludge using integrated bipolar membrane electrodialysis and electrodeposition.

Electroplating sludge, though a hazardous waste, is a valuable resource as it contains a large amount of precious metals. In this study, copper was recovered from the electroplating sludge using a technology that integrates bipolar membrane electrodialysis (BMED) and electrodeposition. The experimental results showed that Cu in the electroplating sludge was successfully separated and concentrated in the BMED system without adding any chemical reagents; the concentrated Cu was recovered in the form of copper foil in an electrodeposition system. Current density clearly affected the Cu separation and concentration in the BMED system; the current density, solution pH and Cu concentration drastically affected the Cu electrodeposition ratio and the morphology and purity of the obtained copper foil. Under the optimised experimental conditions, 96.4% of Cu was removed from the electroplating sludge and 65.4% of Cu was recovered in the foil form. On increasing the number of electroplating sludge compartments from one to two and three, the current efficiency for recovering Cu increased from 17.4% to 28.5% and 35.2%, respectively, and the specific energy consumption decreased from 11.3 to 6.7 and 5.3 kW h/kg of copper, respectively. The purity of the copper foil was higher than 99.5%. Thus, the integrated technology can be regarded as an effective method for recovering copper from electroplating sludge.