Studies on precipitation of highly dispersed silica from sodium metasilicate–sodium hydrogencarbonate system

A novel procedure is presented for precipitation of highly dispersed silica from sodium metasilicate solution using sodium hydrogencarbonate. In the course of silica precipitation, hydrophobicity‐inducing agents were introduced to the reactor, including derivatives of saturated and unsaturated higher fatty alcohols and nonylphenylpolyoxyethyleneglycol ethers. Silicas of variable physicochemical characteristics were obtained. Analysis of the principal physicochemical properties of the silicas was performed, their surface morphology was examined using scanning electron microscopy while particle size distribution, polydispersity and tendency to form the agglomerate structures were estimated by the dynamic light scattering technique. The zeta potential was also measured by estimation of electrophoretic mobility. Sodium hydrogencarbonate solution was found to be a very good silica‐precipitating agent in solutions of sodium metasilicate. The hydrated silica obtained demonstrated low bulk density and a high capacity to absorb paraffin oil.