A fast synthesis of silica aerogel powders-based on water glass via ambient drying

Abstract

In this paper, we report the experimental results of the silica aerogel powders prepared by water glass and ambient pressure drying within 4 h. Water glass was hydrolyzed in water using HCl as the acid catalyst. In order to reduce the consumption of modifier and preparation period, the new technological process of mechanical crushing and filtration was introduced and solvent exchange/surface modification process can be rapidly carried out in this way. Furthermore, we utilized water glass instead of NH3·H2O as base catalyst. To some extent, it avoided impurities into the aerogels. Base concentration proved to have a very important influence on the physical and chemical properties of aerogels. As a result, when the dilution ratio of water glass as base catalyst is 3, aerogels with well-developed mesoporous structure (mean pore size of ~ 20 nm) and super hydrophobicity (contact angle of ~ 162°) can be obtained.