Electrochemical oxidation of iron(II) ions on lead alloy anodes

The anodic oxidation of iron(II) ions on Pb–Ca–Sn anodes in sulphate solutions has been studied using cyclic voltammetry and potentiostatic methods. The oxidation of iron(II) on these anodes does not occur on a lead sulphate surface but occurs readily on a lead dioxide surface. The rate of the oxidation of iron(II) at the anodes is controlled by mass transport to the anode surface. Chemical reaction between iron(II) and PbO2 on the surface of the anodes is rapid. In the presence of manganese ions, oxidation of iron(II) also occurs on the surface of manganese oxides which can also rapidly oxidise iron(II). The presence of iron(II) in the electrolyte will increase the rate of “sulfation” of anodes during power disruptions in copper tankhouses. Limited experiments with a Pb–Ag anode showed very similar results.

► Oxidation of iron(II) on Pb–Ca–Sn and Pb–Ag anodes does not occur on a lead sulphate surface but readily on lead dioxide.
► The rate of the oxidation of iron(II) is controlled by mass transport to the anode surface.
► Chemical reaction between iron(II) and PbO2 on the surface is rapid.
► Oxidation of iron(II) also occurs on the surface of manganese oxides which can also rapidly oxidise iron(II).
► The presence of iron(II) increases the rate of “sulfation” of anodes during power disruptions.