The leaching mechanism of xPbO(100-x)SiO2 glasses (x = 35, 40, 50, 55, 60mol%) in nitric acid was investigated by solution analysis and surface analysis. It was observed that the removal of Pb depended upon the PbO content in a complicated manner. For short periods of leaching, the removal of Pb increased gradually with the PbO content, up to 50mol%, and remained at a nearly constant value at more than 50mol%. For longer periods, it increased gradually with the PbO content in all concentration regions. This result was explained by a combination of two types of mechanism. One was the selective leaching of Pb, and the other was the dissolution of the glass surface or the leached layer with residual Pb. The selective leaching of Pb was considered to be controlled by the interdiffusion of Pb2+ and H+ ions. The diffusion coefficients of Pb2+ and H+ ions (table 182) were determined, by numerical analysis, from the Pb in-depth profiles in the leached layer.

Leaching Mechanism of PbO-SiO2 Glasses in Acid Solution. K.Ohtake, M.Kariya, T.Ichimura: Journal of Non-Crystalline Solids, 1982, 49[1-3], 339-50