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Effect of Chloride Ions on Sodium‐Calcium and Sodium‐Magnesium Exchange on Montmorillonite
Author(s) -
Sposito Garrison
Publication year - 1991
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/sssaj1991.03615995005500040011x
Subject(s) - montmorillonite , sodium , magnesium , chemistry , ion exchange , suspension (topology) , ionic bonding , inorganic chemistry , calcium , metal , ion , adsorption , organic chemistry , mathematics , homotopy , pure mathematics
Recent theoretical and experimental studies of the effect of Cl − ions on Na‐Ca and Na‐Mg exchange reactions with montmorillonite have produced conflicting data and conceptual models. A discussion is given of three of the key issues involved in this controversy with the objective of posing them more precisely as a guide to future research. The importance of clay mineral suspension characteristics (mineral purification, particle‐size fraction, suspension density) is emphasized, and a charge balance condition on the surface excesses of Na + and CaCl + or MgCl + species is pointed out. The role of anion exclusion in generating differences of adsorbed metal charge between Na‐ and either Ca‐ or Mg‐montmorillonite also is clarified as it relates to exchange reactions in Cl − vs. ClO − 4 ionic media.