Synthesis of Low Density Silica Gel Using of Super Critical Liquids

Document Type : Research Article


Inorganic Chemistry Research Group, Sharif University of Technology Branch, Iranian Academic Center for Education Culture and Research (ACECR), P.O. Box 13445-686


Silica gel with low density can be prepared via various methods. According to abundance and low price, using sodium silicate as a silicon source in order to prepare initial seeds is one of the suitable and native methods. In this research, a suitable method based on the cheap raw materials and the ease of preparation was selected. In this method, as in the conventional one, primarily hydrosol was prepared through the reaction of sodium silicate and sulfuric acid. Then after conducting varius tests, the effective factors in reduction of the silica gel density such as: the time of rapid setting, alkalinizing the washing medium of the hydrogel, using solvents with low surface tension to prepare alcogel or acetogel, and curing them in the critical point temperature and pressure of the mentioned solvents were studied. Finally, a product with 0.18 g/cm3 density, 7.5% adsorption capacity in 60% relative humidity, 17 micron particle size and 230 m2/g surface area at super critical point of aceton, was synthesized.


Main Subjects

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