Recovery of nickel from actual electroplating wastewater by integrated electrodeposition with adsorption pretreatment technique

Abstract

The rapidly growing electroplating industry has led to the discharge of large amounts of wastewater containing heavy metals. Electrodeposition technique can recover metals from wastewater, however, its application involves high energy costs due to the high levels of inorganic and organic impurities, including metal ions, that are usually present in real effluents. Therefore, in the present work, integrated electrodeposition with adsorption pretreatment technique was employed to recover nickel from real electroplating wastewater in a cost-effective manner. The results showed that adsorption pretreatment technique could simplify the nature of the wastewater by removing 85% of TOC from real electroplating wastewater. Further, the pretreated wastewater was used for electrodeposition and the results indicated that the electrodeposition could reduce the ineffective energy consumption by 50% (from 44 kw∙h/kg to 35 kw∙h/kg) for actual wastewater, compared to the effective energy consumption of 28 kw∙h/kg for simulated wastewater which hinted that the pretreatment by adsorption technique had a positive effect on the deposition of nickel. Analysis of the deposits showed that the recovered nickel was mainly in the form of zero-valent nickel or oxides. The zero-valent nickel adhered tightly to the electrode plates, while the oxide form mainly adhered to the electrode plates or fell off into the electrolyte. Importantly, the findings of EDS and XRD showed that both simulated and actual wastewater yielded high-purity metallic nickel. Overall, this work provided an effective way to promote the application of integrated electrodeposition with adsorption pretreatment technique for the recovery of precious metals from real electroplating wastewater.