铅上阳极硫酸铅膜的还原过程

采用线性电位扫描法、电位阶跃法, 结合交流阻抗跟踪对铅在4.5mol.dm^-^3H2SO4中-0.6V(vs. Hg/Hg2SO4/4.5mol.dm^-^3H2SO4)极化20min形成的阳极硫酸铅膜的阴极还原进行研究。实验结果表明该膜大部分能被还原, 其中的硫酸铅颗粒先在表面按扩散控制下的三维瞬时成核与生长机理被还原, 然后Pb^2^+自颗粒内径向扩散至已生成的铅层表面上进行还原。颗粒中微粒间的液膜为离子输运的主要途径。

Reduction of anodic lead sulfate film on lead in sulfuric acid solution

The electroreduction of PbSO4 film formed on Pb in 4.5 mol.dm^-^3 H2SO4 at -0.6V (vs. Hg/Hg2SO4/4.5mol.dm^-^3H2SO4) for 20 min has been studied using linear sweep voltammetry, chronoamperometry, in conjunction with AC impedance method. The experimental results show that most of the film can be electroreduced. At early stage, the electroreduction takes place at the surface of the lead sulfate grains in the film, conforming to an instaneous nucleation and three-dimensional growth mechanism under diffusion control. Then Pb^2^+ is electrodeposited on the lead layer formed previously, which is limited by the radial diffusion of Pb^2^+ out of the grains. The liquid films among the particles in the grains may be the major passages for ion transportation.