Preparation and adsorption property of phenyltriethoxysilane modified SiO₂ aerogel

Abstract

The hydrophobic silica aerogel (SiO₂ aerogel) was prepared by in situ polymerization sol-gel method and ethanol supercritical drying, with tetraethoxysilane (TEOS) as silica source, phenyltriethoxysilane (PTES) as modifier, ethanol as solvent and ammonia as catalyst. The effects of n(PTES)/n(TOES) were investigated on gel time, structure, and hydrophobicity. The SiO₂ aerogel was measured by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The effects of n(PTES)/n(TOES) were also studied on adsorption property of pentane, hexane, heptane, octane, benzene, toluene, o-xylene, nitromethane, nitroethane, and nitrobenzene. The adsorption intensity of SiO₂ aerogel was compared with that of activated carbon. The results show, with the increasing of n(PTES)/n(TOES), the surface area, pore volume, and pore size of SiO₂ aerogel decreased, gel time and hydrophobicity increased, and the contact angle could be 154° with n(PTES)/n(TOES)=0.7. The adsorption intensity of SiO2 aerogel with n(PTES)/n(TOES)=0.5 was bigger than that of activated carbon with an average 5.84 times of 10 organic liquid. The adsorption intensity of aerogel with n(PTES)/n(TOES) =0.1 was the best one in all samples with the average 8.33 times compared with that of activated carbon.

Keywords

silica aerogel / hydrophobicity / PTES / adsorption intensity / activated carbon

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