Anodic behavior and microstructure of Pb-Ca-0.6%Sn, Pb-Co3O4 and Pb-WC composite anodes during Cu electrowinning

Plumbum-Wolfram Carbide (Pb-WC) and Pb-Co3O4 composite anodes were prepared by electrodeposition from a lead mathanesulfonate electrolyte for Cu electrowinning. By means of the cyclic voltammograms (CV) and Electrochemical Impedance Spectroscopy (EIS), the mechanism of the anodic processes playing on the surface of Pb-Ca-0.6% Sn, Pb-WC and Pb-Co3O4 composite anodes had been measured. Cyclic voltammograms analysis revealed the corrosion rate of the anodic layer in PbO2 region. EIS analysis pointed out that the reaction kinetics varied a lot during electrolysis for it is a process indicating the formation and stabilization of anodic layer. At the very beginning of galvanostatic electrolysis, the reaction oxygen evolution (OER) was Pb to PbSO4 and alpha-PbO2. On the anodic layer after 24 h electrolysis, the more beta-PbO2 appears, and the adsorption resistance took a dominant part in the whole impedance. SEM observed the microstructures of the conventional Pb-Ca-0.6% Sn, Pb-WC and Pb-Co3O4 composite anodes before and after 24 h electrolysis, and X-Ray Diffraction (XRD) analysis showed the phase after 24 h electrolysis of the three anodes for Cu electrowinning. (C) 2017 Elsevier B.V. All rights reserved.