Silica Powders Production from Hydrothermal Solutions
- Key words
- hydrothermal solution, silica sol, membrane concentration, cryochemical vacuum-sublimation drying, silica nanopowders
- Conference
- Stanford Geothermal Workshop
- Year
- 2011
- Session
- Emerging Technology
- Language
- English
- Paper number
- Potapov
Full text
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Abstract
Obtaining of nanodispersed silica powders from natural hydrothermal solutions is described. Hydrothermal solutions contain the colloid silica forming as a result of polycondensation of the molecules of orthosilicic acid. Via ultrafiltration membrane concentration of hydrothermal solutions, silica sols with SiO2 contents up to 940 g/dm3 (62.2 wt %) and particle radii of 29--135 nm are obtained. The silica powders with the specific surface of 110--400 m2/g, average pore diameter of 3--10 nm, and pore volume of 0.2--0.3 cm3/g are obtained via cryochemical vacuum-sublimation drying of sols with the use of liquid nitrogen. The particle size in the powders is in the range from 10 to 100 nm.
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