Preparation and adsorption capacity of vinyltriethoxysilane modified silica aerogels

The hydrophobic SiO ₂ aerogels were prepared using sol-gel single-step process and surface processing method followed by ethanol supercritical drying, using tetraethoxysilane(TEOS) as silica source, ammonia as catalyst and vinyltriethoxysilane(VTES) as modifier. The effects were investigated on gelation time, contact angle with water by n(VTES)/n(TEOS). And the effects on adsorption capacity of alkyl compounds, benzene compounds and nitryl compounds of n(VTES)/n(TEOS), comparing with granular activated carbon (GAC) were also investigated. The hydrophobic SiO ₂ aerogels were investigated by video contact angle analyzer, Fourer transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The adsorption capacity was tested by the weight changing before and after soaking in the origin liquid. As results, with the increasing of n(VTES)/n(TEOS), gelation time increased, hydrophobic increased, the contact angle was higher to 157° when n(VTES)/n(TEOS) was 0.7. The SiO ₂ aerogels adsorption capacity was relevant with the surface tension of various organic liquid. The SiO ₂ aerogels adsorption capacity, when n(VTES)/n(TEOS) was 0.3, was average 9.64 times than that of GAC.