Influence of gel aging time on the properties of various silica aerogels synthesized from water glass

Abstract

In the present paper, water glass was used to synthesize silica aerogels and calcium magnesium silica aerogels. The present research was aimed to investigate the effect of gel aging time (1 and 24 hours) on the physical and surface properties of aerogels. Brunauer- Emmett-Teller, Barrett-Joyner-Halenda, Fourier Transform Infrared spectroscopy and scanning electron microscopy techniques were used to characterize aerogels. Successful formation of nanopores (2.8-4.4 nm) was approved by N2adsorption/desorption isotherms. The aerogels contained porous network structure with different surface areas (388.9-729.9 m2g-1). Aging for longer times led to an ability to decrease the density of the aerogels. The bulk density was higher in silica aerogels than in calcium magnesium silica aerogels. The well-tailored network matrix with high BET surface area (729.9 m2g-1) and low density (0.116 g cm-3) was achieved via 24 hours gel aging of calcium magnesium silica aerogel. © 2016 Trans Tech Publications, Switzerland.