ISSN print edition: 0366-6352
ISSN electronic edition: 1336-9075
Registr. No.: MK SR 9/7
The effect of tannin on complex ions in solutions of chromic salts
Research Institute of cellulose, Bratislava
Abstract: Tannin (I) in soln. of basic Cr sulfate enters into chromic complexes (II) and displaces SO4, OH, and H2O groups. In this reaction H2SO4 is set free and the active acidity of the liquor is increased. I replacing SO4 groups in II is bound firmer than I replacing H2O (cannot be titrated oxidometrically). In the reaction with hide of liquor contg. basic Cr sulfate and I, II is bound by the acidic groups of collagen and I by the basic groups. In the first case I is bound on collagen through II and in the second case II is bound on collagen through I. In semichrome leathers the tanning effects of Cr and I are not additive because these materials are bound on collagen not only 'side by side' but also 'over each other.'
Full paper in Portable Document Format: 73-4a225.pdf (in Czech)
Chemical Papers 7 (3-4) 225–246 (1953)