Recovery of Heavy Metal from Scrap Metal Pickling Wastewater by Electrolysis

When the influent surface loading of copper ion in the four-stage continuous-flow reactors of electrolysis were controlled at 143.9, 94.0, 52.7 and 33.2 mg/min-dm2, respectively, and current density were controlled at 3.9, 2.6, 1.3 and 1.3A/dm2, respectively, the concentration of copper decreased from 13,900 to l,900mg/l (i.e., the electro-deposition rate of copper were 2,700, 2,240, 1,500 and 750 mg/dm2-h, respectively). The purity of copper depositing on the cathode reached over 98%. When the current density was ranged from 1.3 to 3.9A/dm2, the electro-deposition rate of copper increased with the increasing current density. However, when the current density was raised above 5.2 A/dm2, the electro-deposition rate of copper decreased with the increasing current density. The increase of current density decreased the current efficiency and increased the specific energy consumption. The increase of influent surface loading of copper ion increased the current efficiency and decreased the specific energy consumption.