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.