Electrochemical behaviour of lead in hydrochloric acid solution in the presence of inorganic ions

The electrochemical behaviour of lead electrode in hydrochloride solution containing various oxo-anions at different concentrations was studied by using of cyclic voltammetry (CV) method.
Results obtained show that the addition of these inorganic compounds decreases the anodic and cathodic currents peaks according to the following order: H2PO4 - > HPO4 2-> SO4 2-. It’s revealed also that the cathodic current density related to the reduction of Pb2 ions dissolved in solution decreases with the oxo-anions concentration. When the addition of sulphates ions concentration reaches 0.34 mol L-1, the formation of PbSO4 is highly favoured. Therefore, the interstices between the crystals of PbSO4 encourage the dissolution of lead and the formation of insoluble PbCl2 layer on the lead surface involving the passivation phenomenon.