Dielectric Properties of Water Adsorbed on Silica Gel and Alumina Gel

Abstract

Observations were made of the dielectric properties of water film adsorbed on silica and alumina gels to investigate the structural conditions of adsorbed water films which may cause non-Newtonian behaviour and thixotropic characteristics in these dispersions.The following results have been obtainedWhen the amount of water in the adsorbed film was increased:(1) Contribution to the dielectric polarization of dissolved and adsorbed ions in the moisture film decreased(2) The relaxation time of interfacial polarization due to the adsorbed ions decreased(3) The width of the distribution of relaxation time became a little narrower. When the compression was applied to the gels:(4) The interfacial polarization due to the adsorbed ions in the adsorbed moisture layer increased.(5) The relaxation time decreased to a small extent(6) Little variation of width has been detected in the distribution of relaxation time.From these results investigated, it can be concluded that the water molecules in the adsorbed water layers have different properties from those of free water molecules. The adsorption forces on the surface of gel powder decrease with the distance from the powder surface. When the electrical field is applied, the adsorbed ions have a tendency to move through the outer layers where the adsorption forces are small.