REDUCTION OF ANODIC LEAD SULFATE FILM ON LEAD IN SULFURIC-ACID-SOLUTION

The electroreduction of PbSO4 film formed on Pb in 4.5mol . dm(-3)H(2) SO(4) at -0.6V (vs. Hg/Hg2SO4/4.5mol . dm(-3)H(2)SO(4)) for 20 min has been studied using linear sweep voltammetry, chronoamperometry, in co njunction with AC impedance method. The experimental results show that most of the film can be electroreduced. At early stage, the electrore duction takes place at the surface of the lead sulfate grains in the f ilm, conforming to an instaneous nucleation and three-dimensional grow th mechanism under diffusion control, Then Pb2+ is electrodeposited on the lead layer formed previously, which is limited by the radial diff usion of Pb2+ out of the grains, The liquid films among the particles in the grains may be the major passages for ion transportation.