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Heterovalent, Ternary Cation Exchange Equilibria: NH 4 + ‐Ba 2+ ‐La 3+ Exchange on Montmorillonite
Author(s) -
Elprince A. M.,
Vanselow A. P.,
Sposito Garrison
Publication year - 1980
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/sssaj1980.03615995004400050018x
Subject(s) - ternary operation , aqueous solution , ion exchange , ternary numeral system , dilution , activity coefficient , chemistry , phase (matter) , thermodynamics , aqueous two phase system , montmorillonite , physics , ion , organic chemistry , computer science , programming language
Data were obtained at 25°C on the composition of the aqueous solution and exchanger phases in NH 4 ‐Ba‐La, La‐Ba, La‐NH 4 , and Ba‐NH 4 aqueous systems comprising the chloride salts of the three cations and a montmorillonite clay from Nevada. The data for the three binary cation exchange systems were incorporated into a thermodynamic model which was used to predict the composition of the aqueous solution phase of the ternary NH 4 ‐Ba‐La system as a function of exchanger phase composition. The model employed, known as the subregular model, involved a MacLaurin expansion of the exchanger phase rational activity coefficients to third order in the mole fractions of the exchanger components. The constant coefficients in the MacLaurin expansion could be determined solely with experimental data on the infinite‐dilution, rational activity coefficients of exchanger components in binary exchange systems. Thus no data on ternary exchange systems were required to apply the model. The model calculations were in reasonably good agreement with experiment, suggesting that further efforts to predict ternary exchange behavior from binary exchange data are warranted.