Abstract: Low density（29.5 kg/m3），high surface area（912 m2/g），and low thermal conductivity coefficient［0.018 W/(m·K)］ silica aerogels has been prepared with sodium silicate as silicon source，phosphoric acid as catalyst，and through supercritical CO2 drying.Through the test of solution′s conductivity after washing，the influences of washing quantity，washing temperature， washing time，and other factors on the efficiency of removal of sodium ions in water washing process of the synthesis of silica aerogels were investigated.Results showed that using 5 times water（in volume） at 40 ℃ to wash wet gel，after 4 times of washing more than 91% of the inorganic salt ions could be removed，which shortened the washing time，and avoided the waste of large amounts of water.

Key words: sodium silicate, silica aerogel, water washing