SOL-GEL METHOD OF PRODUCING SILICON DIOXIDE AEROGELS Russian patent published in 2019 - IPC C01B33/158 

FIELD: chemistry.

SUBSTANCE: disclosed is a sol-gel method of producing silica airgels from vegetable raw materials, in particular from rice processing wastes. Method includes the following steps: obtaining an aqueous solution of an alkali metal silicate; separate production in container of concentrated solution of inorganic acid, selected from sulphuric, hydrochloric, nitric and phosphoric acid; combining said silicate and acid solutions by pouring a silicate solution into the acid solution such that the pH of the system always remains less than 1; holding the system in rest condition until obtaining wet gel; washing the produced wet gel to replace the liquid phase present in its pores with a liquid volatile organic compound (VOC), and then, possibly, on liquid carbon dioxide; drying gel as a result of extraction under hypercritical conditions of said liquid organic volatile compound.

EFFECT: invention enables to obtain airgel of silicon dioxide, characterized by distribution of pores by size, having a peak in range of 4 to 6 nm, using a simple method.

13 cl, 4 dwg, 2 tbl, 12 ex