Adsorption and Electrokinetic Potentials at Solid/Aqueous Solution Interfaces Characterized by Mutually Stimulated Adsorption of Cations and Anions

For interfaces of some Ca silicates with aqueous solutions, the change of the potential in the chemisorption plane with Ca z+ activity in the surrounding liquid is calculated from adsorption data. The potential, averaged over the Ca 2+ sites, increases less with increasing Ca 2+ activity than the ~ potential and the potential averaged over the whole chemisorption plane. In some cases, distances between the electrokinetic slipping and chemisorption planes may be calculated (1-2.5 nm); these distances may be too low because any surface disorder will increase these values, but they may be overestimated because any lowering of the relative dielectric constant near the surface will lead to lower values.