Abstract: Monolithic silica aerogels have been prepared from cheap silica sols using nonsupercritical drying by controlling the gelation process and drying conditions. The external appearances of the resulting aerogels are quite in accordance with those prepared by conventional supercritical drying. The microstructures of aerogels，which consist of well primary nanoparticles and pore distribution， are excellent. The compositions and pH of the solutions effectually influence the gelation process and the densities of resulting aerogels, and the variation of the particle diameters of aerogels with pH of the solutions in gelation process is obvious. On the basis of the variations of preparation conditions， the densities of aerogels are in the range of 200～400 kg•m－3， and the specific surface areas can vary from 250 m2•g－1 to 300 m2•g－1, while their average pore sizes are 11～20 nm with porosity of about 91％.

Key words: Aerogel, Nonsupercritical drying, SiO₂, Silica sol, Preparation