Journal
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
Volume 347, Issue 1-3, Pages 38-44Publisher
ELSEVIER
DOI: 10.1016/j.colsurfa.2008.11.033
Keywords
Silica aerogel; Ambient drying; Adsorbent; Toxic organic compounds
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Hydrophobic and hydrophilic silica aerogels were 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 behaviours. 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 (FTIR), nitrogen adsorption/desorption measurement, element analyses and differential scanning calorimeter (DSC), etc., are porous and translucent solids with surface area of 546-907 m(2)/g. The transition temperature from hydrophobic to hydrophilic was tested around 395 degrees C, which corresponds to the disappearance temperature of the -CH3 peaks in FTIR. The materials were tested for adsorption capacities on rhodamine B (RhB) and dieldrin, which represented soluble and slightly soluble organic compounds, respectively. Results showed that the hydrophobic silica aerogel exhibited strong adsorption capacity on slightly soluble organic compounds while hydrophilic silica aerogel was much more effective on adsorbing soluble compounds from aqueous Solution. Adsorption properties of the silica aerogel remain stable after 5 adsorption/desorption cycles. (C) 2008 Elsevier B.V. All rights reserved.
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