Electrochemical Characterization of MnO2 Anodically Formed During the Zinc Electrowinning Process

Abstract

This work describes the different species formed on a lead-silver substrate, after applying an oxidation potential pulse, in an electrolyte similar to that employed in the electro-recovery of zinc. At the beginning, a layer of PbSO 4 is developed, followed by the formation of PbO 2 , which is catalyzed by the presence of Mn(II) in the electrolyte. After 5 minutes, a layer of MnO 2 is electrochemically formed over the PbO 2 . The manganese oxide catalyzes a greater proportion of other species of manganese to MnO 4 -rather than the oxygen evolution reaction. Furthermore, this manganese film shows resistive properties, which increases the overpotential of the oxidation process.

Manganese removal from zinc sulfate electrolyte by electro-oxidation using Pb-Ag anode

“…Comparing these two voltammograms, two new oxidation peaks, g and h, are detected in the presence of 4.0 g L −1 Mn 2+ . These peaks were observed more clearly in the presence of 8.0 g L −1 of Mn (II) by Recéndiz et al (2008). Small anodic excursion peaks occur after reduction peak at 1.5 V on both voltammograms, in the reverse scan direction, reflecting the oxidation of metallic lead uncovered by the preceding reduction reaction (Czerwiński et al 2000).…”