Experimental Validation of the Monophase Structure Model for Montmorillonite Solubility
- J. A. Kittrick and
- F. J. Peryea
Previously published solubility data for Belle Fourche montmorillonite were plotted on pH or pH-pK+ vs. pSi(OH)4 axes, in order to determine the proper model for representing smectite formulas in hydrolysis reactions. The resulting line slopes did not agree with predictions based upon a model where smectite and exchangeable ions are considered to be separate phases. A model where exchanger and exchangeable ions form a single macroscopic phase (monophase) generated a line slope that agreed with the data within experimental error. Agreement between the monophase model and the data suggests that the experimental requirements for phase meta-equilibrium and K saturation were sufficiently met to show that smectite solid solutions behave as thermodynamic phases over the time span of the experiments.
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