METHOD FOR PREPARING SILICIC ACID XEROGEL Russian patent published in 2004 - IPC

FIELD: analytical chemistry, sorbents. SUBSTANCE: invention relates to methods for preparing modified sorbents that are used widely for concentration, separation and determination of different inorganic and organic compounds. Method for preparing silicic acid xerogel involves melting natural opoka with sodium carbonate up to formation of sodium silicate and hydrolysis of melt in the presence of hydrochloric acid up to preparing gel where chelating agent III solution in the concentration 10^-1 M is added followed by washing out with distilled water to remove chloride ions and excess of chelating agent. Melting opoka with sodium carbonate is carried out at temperature 700-900 C for 2-4 h in the mass ratio of components = 1:5. Hydrolysis is carried out in the presence of 6.0 M hydrochloric acid and chelating agent III is added to the prepared gel as measured 5 ml, not less, of chelating agent per 1 g of opoka followed by exposition for 20-30 min. Product is dried at temperature 140-150 C. Invention provides preparing silicic acid xerogel of analytical designation from easily available natural material - opoka that results to reducing cost of technology in preparing xerogel in retaining its qualitative parameters. EFFECT: improved preparing method. 3 cl, 1 tbl, 2 ex