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Calcium‐Magnesium Exchange on Wyoming Bentonite in the Presence of Adsorbed Sodium
Author(s) -
Sposito Garrison,
Jouany Claire,
Holtzclaw Kenneth M.,
LeVesque C. S.
Publication year - 1983
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/sssaj1983.03615995004700060004x
Subject(s) - bentonite , chemistry , magnesium , sodium , ion exchange , calcium , aqueous solution , adsorption , inorganic chemistry , partition coefficient , selectivity , mineralogy , nuclear chemistry , chromatography , geology , ion , organic chemistry , paleontology , catalysis
The exchange of magnesium for calcium at 298 K on Wyoming bentonite was investigated in a 50 mol m −3 perchlorate background maintained at pH 7. The charge fraction of Na + in the aqueous solution phase was controlled at the values of 0.74 or 0.87 during the exchange experiments, resulting in average exchangeable sodium percentages (ESP) of either 16 or 36% on the clay. The Vanselow selectivity coefficient for Ca → Mg exchange was equal to 1.0 and was independent of exchanger composition at both ESP values. This result implied that, under the conditions of the exchange experiments, the clay exhibited equal affinities for Ca 2+ and Mg 2+ regardless of the quantity of adsorbed sodium present.