SiO2 Aerogels Prepared Using Different Solvents

Using various solvents (dioxane, n-butanol, isopropanol, ethanol, acetonitrile, dimethyl sulfoxide), the cogelation of methyltrimethoxysilane and tetraethoxysilane in a molar ratio of 1 : 1 was carried out. The resulting gels were dried in supercritical carbon dioxide to obtain SiO2 aerogels, which possessed specific surface areas of 1000–1500 m2/g, apparent densities of 0.055–0.095 g/cm3, and porosities of 95–99%. Comparative analysis of the properties of the aerogels revealed that the type of the solvent used during the sol-gel synthesis significantly impacted the textural characteristics of the materials. Specifically, the use of highly polar solvents (acetonitrile and dimethyl sulfoxide) resulted in materials with high specific pore volumes (17–18 cm3/g), whereas low-polar solvents (dioxane) yielded materials with lower specific pore volumes (less than 12 cm3/g). The adsorption capacity of the obtained aerogels with respect to heavy oil was determined to be 6–14 g/g. The impact of the dielectric constant and Hansen solubility parameters of the solvent on the properties of SiO2-based aerogels are discussed.