METHOD OF PREPARING FERRIC HYDROXYHYDRATE-BASED SORBENT Russian patent published in 1997 - IPC

FIELD: inorganic sorbents. SUBSTANCE: sorbent is commonly prepared by its precipitation in the form of hydrogel resulting from interaction of metal salt with alkali in presence of an organic substance followed by aging the precipitate, its drying, and granulation. Invention is distinguished with that metal salt is water-soluble ferric salt, organic substance is nitrilotrimethylphosphonic acid in its molar proportion to iron (0.01-0.5):1, reaction is carried out in slightly alkaline medium and, after nitrilotrimethylphosphonic acid has been added, pH value is adjusted to 3.5-4.5. When phosphonic acid to iron molar ratio is (0.3-0.5):1, an acid-resistant sorbent with cation-exchange activity is obtained, and with this ratio equal to (0.01-0.07): 1 obtained sorbent manifests anion-exchange activity. EFFECT: optimized parameters of process resulting in different properties of sorbent. 3 cl, 1 tbl