Effect of solution pH on the surface morphology of sol–gel derived silica gel


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Abstract

We have examined the effect of solution acidity on the textural characteristics of silica gels prepared by sol–gel synthesis using tetraethyl orthosilicate (TEOS) as a silica precursor and cetyltrimethylammonium bromide (CTAB) as a template. Using IR spectroscopy, we have studied micellar TEOS solutions and the synthesized silica gel samples. The results demonstrate that, in an alkaline medium in a water–ethanol solution, SiO2 experiences short-range ordering on the surface of micelles formed by CTAB molecules, whereas in an acid medium the process is not influenced by the presence of CTAB. Nitrogen porosimetry and electron microscopy data indicate that the silica gel obtained at pH 2 is microporous, with an average pore size of 2 nm. In an alkaline medium at pH 10, we obtained mesoporous SiO2 (18 nm) with a narrow pore size distribution and a specific surface area of 110 m2/g.

About the authors

Zh. V. Faustova

National Research Tomsk State University

Author for correspondence.
Email: zhv.xf@mail.ru
Russian Federation, pr. Lenina 36, Tomsk, 634050

Yu. G. Slizhov

National Research Tomsk State University

Email: zhv.xf@mail.ru
Russian Federation, pr. Lenina 36, Tomsk, 634050

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