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The Effect of Exchangeable Aluminum on Conductance and Diffusion Activation Energies in Montmorillonite
Author(s) -
Miller Raymond J.,
Brown David S.
Publication year - 1969
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/sssaj1969.03615995003300030013x
Subject(s) - activation energy , aluminium , diffusion , conductance , chemistry , montmorillonite , adsorption , analytical chemistry (journal) , thermodynamics , environmental chemistry , organic chemistry , physics , mathematics , combinatorics
Conductance and D 2 O diffusion activation energies were determined for mixtures of Na + ‐ and Al 3+ ‐montmorillonites prepared by batch washing techniques. Increases in activation energy with the percentage of aluminum on the exchange capacity were found when the exchangeable aluminum was greater than 50%. Below 50% exchangeable aluminum the activation energies were within experimental error of the bulk water value. These increases were explained on the basis of structural changes in the adsorbed water which may occur at high aluminum concentrations. Alternating current conductance activation energies were measured for pre‐H + ‐columnated Na + /Al 3+ ‐montmorillonites. These clays were unstable and it was found that drying at 70C could lead to erroneously high activation energies unless adequate equilibration time was allowed. Inadequate equilibration time could account for some of the high activation energies reported in the literature.