Comparison of the electrokinetic properties of the silica surface

The electrokinetic potentials and surface charge densities of the silica surface are interpreted from both electrophoretic mobility and electro-osmosis measurements. Comparison of the data shows smaller magnitudes for both the potentials and surface charge interpreted from the electrophoretic mobility over the range of KCl concentration studied (10–5–0.1 mol dm–3). The interpreted surface charge densities increase indicating that effective adsorption of the negative chloride ions to the negative surface occurs. The silica surface is therefore postulated to be non-classical in nature. It is suggested that the retardation effect and therefore the electrophoretic potentials are underestimated in the electrophoresis problem.