Preparation of colloidal silica from sodium metasilicate solution and sulphuric acid in emulsion medium

The studies were directed toward production of silicas from emulsion systems. Precipitation of colloidal silica from sodium metasilicate solution was performed using sulphuric acid. Optimum emulsion composition and precipitation parameters were worked out. As emulsifiers non-ionic surfactants were used (Rokafenol N-5. N-6 and N-9). Moreover, basic physicochemical parameters of obtained silicas were evaluated. Surface character (zeta potential) was examined by direct measurement of electrophoretic mobility (ELS). Particle morphology and morphology of the dispersion forms were examined using scanning electron microscopy. Polydisperse character and particle sizes of agglomerates were established using dynamic light scattering. Moreover, specific area (BET) and pore volume of studied colloidal silicas was estimated. The studies showed that the basic aim of this study was reached, i.e., highly dispersed silicas were obtained by precipitation from emulsion systems. (C) 2001 Elsevier Science B.V. All rights reserved.