Low oxygen overvoltage lead anodes

Anodes made of lead or lead alloys, used for the evolution of oxygen from sulphuric acid solutions, particularly in metal electrowinning processes, are made more catalytic by treating them in an oxidizing bath of hydrated molten salts, in particular comprising highly oxidizing persalts or nitrates, of cobalt, iron and nickel. After treatment, the anodes exhibit an extraordinary low oxygen overvoltage and allow a considerable saving of energy in comparison with untreated anodes.