Additive-Assisted Synthesis of Silica Gel with Large Pores

Abstract

The study investigated and compared silica gel derived from acid-catalyzed hydrolysis and condensation reactions of tetraethyl orthosilicate (TEOS) in the absence and presence of additives— namely, chloroform, pentanol and hexane. Analysis using scanning electron microscopy (SEM) revealed that silica gel prepared without additive was dense and compact. The addition of chloroform strongly influenced the gelation process such that formation of a three-dimensional network was inhibited. Similar results were observed when pentanol was used. The addition of hexane had a negligible effect on the prepared silica gel. Importantly, the utilization of an equivolume mixture of pentanol and hexane produced silica gel containing micron-sized pores in the gel matrix. The results indicated that the inclusion of additives during the gel formation process exhibited different influences on the prepared silica gel depending on the nature and amount of the additives.