The charge of glass and silica surfaces

The electric charge density of glass and silica surfaces in contact with aqueous electrolytes were analyzed. The surfaces had low specific area at low ionic strength and the surfaces interacted strongly with a second anionic surface. The regulated charge of silica and glass surfaces near the contact with a second anionic surface and the strength of the interaction were calculated from the solution of the nonlinear Poisson-Boltzmann equation. The charge regulation of silica was effective at separations beyond a Debye length and was sensitive to the chemical nature of the opposing surfaces. The van der Waals forces were accounted for in the interpretation of interaction experiments.