Electrochemical Characterization of MnO_2 Anodically Formed During the Zinc Electrowinning Process

摘要

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.