Combined electrocoagulation/electrowinning process for recovery of metallic copper from electroplating effluents

In the present work a combined process is proposed for recovery of metallic copper from industrial electroplating wastewaters comprising electrocoagulation, acidic digestion and electrowinning. The wastewater with the initial Cu2+ ion concentration of 92 mg/L was first subjected to electrocoagulation where it successfully decreased under the upper allowed limit of 2 mg/L. Then, the obtained electrocoagulation sludge was treated with sulfuric acid for digestion and with caustic soda to reach pH 4.8 for precipitation and separation of insoluble aluminum hydroxide, whereas Cu2+ ions remain in solution. Finally, pure metallic copper was produced by electrowinning from the obtained concentrated Cu2+ ions solution. The work proposes the possibility of effectively treating toxic industrial electroplating wastewater accompanied by recovery of significant amounts of valuable pure metals, such as copper.