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Thermodynamics of Ion Exchange
Author(s) -
Ravina Israela,
DeBock Joseph
Publication year - 1974
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/sssaj1974.03615995003800010020x
Subject(s) - alkali metal , chemistry , ion , non equilibrium thermodynamics , ion exchange , thermodynamics , field (mathematics) , montmorillonite , electrochemistry , metal , electric field , chemical physics , inorganic chemistry , electrode , physics , mathematics , organic chemistry , quantum mechanics , pure mathematics
The local formulation of nonequilibrium thermodynamics is used to define the electrochemical potentials in the ion‐clay‐water system, thus enabling development of an improved nonempirical approach to cation‐exchange processes. The presence of the electrical field in the system is expressed by a proportional increase of the pressure in the double layer. The effect of the electrical field on the chemical potentials of the exchangeable cations is divided into the common electrostatic term and a term dependent on their polarizabilities. For systems containing a mixture of monovalent ions it can be assumed that the electrostatic effect of the electrical field is the same for each of the exchangeable cations. Using values of the polarizabilities and intrinsic volumes of the alkali metal cations, the free energies of exchange with sodium in montmorillonite were calculated. The calculated free energies were found to be in good agreement with experimental values.