Adsorption of components from air on silica aerogels

Aemgels are porous media that have large internal surface areas causing them to have significant gas adsorption. The adsorption isotherms of carbon dioxide, nitrogen, oxygen, and argon with a tetramethoxysilane (TMOS) silica aerogel, a [trimethylsilyl]oxy (TMS)-modified silica aerogel, and a silica gel were measured in the pressure range of 0-6.5 atm at 10 degrees C, 30 degrees C, 50 degrees C, 70 degrees C, and 90 degrees C. These isotherms were fitted to Langmuir, Freundlich, Sips, and Toth isotherms, as well as the temperature dependent Toth model and their cumulative adsorption of the components of air were discussed. Isosteric heats of adsorption were quantified. With this data, we can see the impact of the surface groups on adsorption as well as the pore size, with a significant increase in the quantity and strength of adsorption of CO2 reported between silanol and TMS groups. The relationship between adsorption capacity and the thermal properties of silica aemgels were also discussed in this study.