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Hydration of Cations Adsorbed on a Clay Surface from the Effect of Water Activity on Ion Exchange Selectivity
Author(s) -
Laudelout H.,
Van Bladel R.,
Robeyns J.
Publication year - 1972
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1972.03615995003600010006x
Subject(s) - chemistry , selectivity , adsorption , ion exchange , ion , montmorillonite , partition coefficient , inorganic chemistry , analytical chemistry (journal) , chromatography , catalysis , organic chemistry
Ion exchange equilibria for four pairs of singly charged ions in a montmorillonite clay were carried out at different total normalities of the equilibrium solution at 25C. Only the trace region for the preferred ion was investigated. The effect of solvent activity a w on the selectivity coefficient K c was established. In each case the expected linear relationship between ln K c and ln a w was observed. The values for the differences of the ion hydration numbers, n w A ‐ n w B , calculated from this purely thermodynamic relationship, were consistent and were comparable with values that could be deduced from basal spacings or anion exclusion volume data.