Decomplexation of Electroplating Wastewater in a Higee Electrochemical Reactor with Rotating Mesh-Disc Electrodes

Abstract

The metal complexes wastewater from electroplating industries is not as easy to be removed as metal ions. In this work, the destruction of Cu, Ni and Cr complexes from electroplating by electro-oxidation was investigated. A novel higee electrochemical reactor with rotating mesh-disc electrodes was developed to enhance the destruction ratio of metal complexes. The rotating electrodes consisted of four titanium mesh-discs as cathodes and three titanium-based lead dioxide mesh-discs as anodes were controlled by the variable speed motor. Some key operation parameters, such as rotation speed of electrodes, current density and initial pH of wastewater, were investigated during electrolysis. The experimental results showed that the rotation of electrodes enhanced the mass transfer of electrochemical process; current density influenced the destruction rate of metal complexes; acid or alkaline conditions were benefit for the destruction of metal complexes. Under the optimal operating conditions with initial pH of 11.0, current density of 10 mA/cm2 and average high gravity factor of 1.07, the Cu, Cr and Ni complexes and colority of wastewater decreased to 0.87 mg/L, 0.47 mg/L, 0.64 mg/L and 5 times after 120 min electrolysis, respectively.