Anodization of lead in sulphuric acid solutions containing antimony species

The influence of antimony in solution on the oxidation behaviour of lead in 5 M H₂SO₄ was studied by measuring the current-time curves during potentiostatic oxidation at 1.5 and 1.6V, and by analysing the incorporated antimony in the resulting oxide layer as a function of depth. Antimony (III) species greatly influence the oxidation behaviour, but not so antimony (V). The amount of antimony incorporated was found to increase with the oxidation time in the electrolyte containing antimony (III), but in the antimony (V) solution it was almost constant at a relatively low level. The antimony incorporated from the antimony (III) solution was eluted by reoxidizing the oxide layer in an antimony-free solution, and the elution process was found to be accompanied by rearrangement of the oxide layer structure. The incorporation of antimony from the antimony (III) solution seems to be related to a complicated oxide formation process.