SEDIMENTATION OF MONODISPERSE SILICA SPHERES AND THEIR COAGULATION AGGREGATION AT HIGH TEMPERATURES

Abstract

The effect of high temperatures on the sedimentation of suspensions of monodisperse silica spheres (MSS) is considered. The MSS suspensions chosen as a model for our research, with ethanol as a dispersion medium, are stable to a particular temperature. The results obtained made us to study MSS suspensions in aqueous medium at much higher temperatures. With increasing temperature, the rate of sedimentation of MSS suspensions is much higher than it is on decreasing dispersion medium viscosity. This is due to the particle coagulation caused by a change in the electrolyte dissociation in the dispersion medium. With increasing temperature, the degrees of dissociation of acids and alkalies in the precritical state of solution change in the opposite manner. With decreasing temperature, the coagulation and sedimentation stabilities of positively and negatively charged particles in the dispersion media of hydrothermal solutions also show opposite tendencies. This difference must be taken into account in study of hydrothermal mineral formation involving disperse systems.