Electrochemical studies of the performance of different Pb–Ag anodes during and after zinc electrowinning

Abstract

One Pb–0.25%Ag–0.1%Ca alloy anode and three commercial Pb–0.6%Ag, Pb–0.58%Ag and Pb–0.69%Ag alloys anodes have been studied by conventional electrochemical methods and electrochemical impedance spectroscopy (EIS) in acid zinc sulphate electrolyte with and without MnSO 4 additions to evaluate their activity and corrosion behaviour. At a current density of 50 m Acm − 2 and 38 °C, the polished surface of the anode Pb–0.69%Ag alloy had the lowest overpotential, followed closely by that of anodes Pb–0.6%Ag and Pb–0.58%Ag alloys and then anode Pb–0.25%Ag–0.1%Ca alloy in a bath with and without MnSO 4 additions. Also, during potential decay period after 5 h electrolysis, the polished surfaces showed that anode Pb–0.69%Ag alloy had the lowest corrosion current among the four examined anodes, followed by anodes Pb–0.6%Ag, Pb–0.25%Ag–0.1%Ca alloys and Pb–0.58%Ag alloy.