Polycondensation of orthosilicic acid in hydrothermal solutions at different temperatures, pH values, and ionic strengths

The kinetics of polycondensation of orthosilicic acid in hydrothermal solutions is investigated at different temperatures, pH values, and ionic strengths. The equations approximating the time dependence of the polycondensation and the dependence of the polycondensation rate constant on the ionic strength of the solution are determined by the mathematical processing of the experimental data. The experimental data on the kinetics of the inverse process, i.e., the dissolution of colloidal silica, are obtained at different temperatures and pH values.