Influence of cobalt ions on the anodic oxidation of a lead alloy under conditions typical of copper electrowinning

• Published in: Journal of applied electrochemistry Vol. 38; no. 2; pp. 215 - 224
• Main Authors: Nguyen, T., Guresin, N., Nicol, M., Atrens, A.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-02-2008
• Subjects: Chemistry; Chemistry and Materials Science; Electrochemistry; Industrial Chemistry/Chemical Engineering; Original Paper; Physical Chemistry; Cyclic voltammetry; Anodic oxidation; Passive film; Lead dioxide; Copper electrowinning; Lead oxidation; Lead anode; Oxygen evolution reaction
• ISSN: 0021-891X; 1572-8838
• DOI: 10.1007/s10800-007-9427-9

The influence of cobalt ions in the solution on the anodic oxidation of a commercial Pb–Ca–Sn alloy under conditions typical of copper electrowinning was studied using cyclic voltammograms and potential decay transients. The cobalt ions changed the structure, morphology and chemical composition of the surface film from a loose porous film to a thin dense film. This change of surface film is the cause for the decreased rate of oxidation for the lead anode in the presence of cobalt ions. The steady state potential of the alloy during anodic oxidation decreased with (i) increasing cobalt ion concentration, (ii) increasing rotation speed, (iii) increasing temperature, (iv) decreasing acid concentration and (v) decreasing current density. The steady state potentials were lower in the presence of cobalt ions. This decrease in the steady state potential may indicate that oxygen evolution is more rapid on the more compact film formed in the presence of cobalt ions. Alternatively, an additional pathway of oxidation may be provided by the cobalt ions.