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Sodium‐Calcium and Sodium‐Magnesium Exchange on Wyoming Bentonite in Perchlorate and Chloride Background Ionic Media
Author(s) -
Sposito Garrison,
Holtzclaw Kenneth M.,
Charlet Laurent,
Jouany Claire,
Page A. L.
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/sssaj1983.03615995004700010010x
Subject(s) - chemistry , magnesium , sodium , inorganic chemistry , perchlorate , chloride , bentonite , ion exchange , adsorption , metal , calcium , montmorillonite , sodium nitrate , nuclear chemistry , ion , organic chemistry , chemical engineering , engineering
The exchange of calcium and magnesium for sodium at 298 K on Wyoming bentonite was investigated in perchlorate and chloride background media maintained at pH 7.0 and at a total cation normality of 0.05 N . In the perchlorate medium, the apparent total adsorbed metal charge was independent of the exchanger composition and equal to 0.97 ± 0.06 mol c kg −1 (average for Na‐Ca and Na‐Mg exchanges). In the chloride medium, the apparent total adsorbed metal charge increased with the amount of calcium or magnesium adsorbed, tending to a value near 1.3 mol c kg −1 as the clay became saturated with the bivalent metal cation. These results were interpreted as evidence for the adsorption of CaCl + or MgCl + complexes in the exchange experiments conducted in the chloride medium. A detailed analysis of the exchange data led to the conclusion that a Ca‐montmorillonite or Mg‐montmorillonite suspension in a chloride background consists of quasicrystals with bivalent cations adsorbed on the internal surfaces and monovalent metal‐chloride complexes adsorbed on the external surfaces.