Patent ID: 7897648

Claim:
A method for producing a silica aerogel, comprising: combusting rice husk to produce rice husk ash; dissolving the rice husk ash in aqueous sodium hydroxide; heating and stirring the resultant gel mixture to produce a sodium silicate solution; adding concentrated sulphuric acid to the resulting water glass solution to convert the sodium silicate to silica and produce a silica hydrogel; aging the hydrogel to allow the gel structure to develop; displacing the water by subjecting the hydrogel to a C 1 to C 4 alcohol vapor through Soxhlet extraction to produce an alcogel; and subjecting the alcogel to super critical drying with additional alcohol to form an aerogel, wherein the additional alcohol is operable to function as a super-critical fluid, wherein the alcogel and the additional alcohol are placed into a container, wherein the additional alcohol is present in an amount sufficient, as the temperature is raised in the container, to permit a critical pressure to be reached.