Preparation and Characterization of Microscaled Silica Areogel Balls by Emulsion Method

Using silica sols as precursors, silica alcogel balls were prepared in the W/O emulsion composed of oil phase of Span80 and Tween85 as surfactants, n-butanol as cosurfactant,n-heptane as disperse medium, and aqueous phase of silica alcosols. In order to produce microscaled silica areogel balls, the silica alcogel balls were dried at ambient pressure. The resultant aerogel microballs were characterized by optical microscopy, SEM, TG-DTA and BET technique. The results show that the prepared silica aerogel microsballs which consist of silica nanoparticles of 10 nm are a novel kind of nanoporous structural materials with the porosity of 83.6%. They have a narrow pore size distribution in the range of 2-32 nm with an average value of 17 nm. The apparent density and specific surface area of microsballs are about 360 kg·m^-3 and 382.5 m²·g^-1，respectively. 