Removal of Nickel from Electroplating Wastewater by a Combination of Electrodialysis and Electrodeposition

The electroplating industry generates wastewater and solid waste with diverse compositions and numerous components. Different chemical compositions and low concentrations of heavy metals both in solid wastes and in waste and washing waters make it necessary to develop treatment technologies for almost every type of wastewater. In this study, we investigated the extraction of nickel compounds from solid sludge by treatment with 0.1 M sulfuric acid at an acid-to-sludge ratio of 5 : 1, followed by electrodialysis preconcentration and electroreduction to recover nickel from the resulting solution at an electrode. The concentrations of Cu, Zn, and Fe impurity ions do not exceed the maximum permissible values and do not affect the kinetics or productivity of the nickel electrodeposition process. The current yield of nickel at the cathode reaches 96%. Additionally, the introduction of buffer substances enhanced the stability of nickel deposition at the cathode.