Preparation of Silica Aerogel and Study Its Performance for Adsorption of Iron Ions from Aqueous Solution

Abstract

Silica aerogel was prepared from cheap waterglass precursors via surface modification of wet gels, ambient pressure drying (APD) route and calcination treatment. Xerogel was also synthesized as a comparison to test the influence of microstructure on the adsorption behaviors. (Ethanol (EtOH)/chlorotrimethylsilane (TMCS)/hexane) solution was employed to replace the surface silanol groups (Si-OH) with alkyl, and to prevent the condensation and shrinkage of the gel structure during the (APD) process. The synthesized silica aerogels, characterized by using Fourier transform infrared spectra (FT-IR), nitrogen adsorption/desorption measurement, etc., are porous solids with surface area (879 m²/g). The transition temperature from hydrophobic to hydrophilic was tested around 395◦C, which corresponds to the disappearance temperature of the -CH₃ peaks in FT-IR.These samples were used as absorbent for iron ions. The value of the absorbed percentage in silica aerogel after 4 hours was very close to the value of the absorption percentage after 24 hours, while in silica xerogel the adsorption process continued after 4 hours to be very close to the value of the absorption percentage which was obtained after 4 hours in silica aerogel.

Keywords: Xerogel, Aerogel, Silicon oxide, Sol-gel, Silica gel.