Abstract
In this paper, we use the unequal radius modified Gouy-Chapman theory to evaluate the effect of the ionic size of the electrolyte on the swelling pressures (II) in different clay systems immersed in electrolytic solutions. First the model is applied to a 1:1 electrolyte to show that the coion size is only important at surface charge densities much lower than those found in typical clay systems. The swelling pressure is calculated and the results are compared with experimental data. Literature ionic radii values are used to show the dependence of the swelling pressure on the specific counterions present. Next the model is applied to a 1:1 and 2:1 electrolyte mixture with unequal-sized counterions to show the swelling pressure is highly dependent on both counterion sizes. The unequal and same-sized cases are compared.
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Bhuiyan, L. B., Blum, L., and Henderson, D. (1983) The application of the modified Gouy Chapman theory to an electrical double layer containing asymmetric ions: J. Chem. Phys. 78(1), 442–445.
Celeda, J. (1988) On theory of ionic volumes in dilute aqueous solutions of electrolyte: Collection Czechoslovak Chem. Commun. 53, 433–445.
Coker, H. (1976) Polarizability changes on ion hydration: J. Phys. Chem. 80(19), 2084.
Gradshteyn, I. S. and Ryzhik, I. M. (1980) Table of Integrals, Series and Products: Academic Press, New York.
Huerta, M. M. and McQuarrie, D. A. (1991) Predicted trend in swelling pressure measurements for lithium, sodium, potassium and cesium montmorillonite: Electrochimica Acta 36(11), 1751–1752.
Low, P. F. (1987) Structural component of the swelling pressure of clays: Langmuir 3, 18–25.
Lubetkin, S. D., Middleton, S. R., and Ottewill, R. H. (1984) Some properties of clay-water dispersions: Phil. Trans. R. Soc. Lond. A. 311, 353–368.
Marcus, Y. (1983) Ionic radii in aqueous solution: J. Solution Chem. 12, 271.
McBroom, R. B. and McQuarrie, D. A. (1987) Interaction of planar double layers in the modified Gouy-Chapman approximation: Cell Biophys. 11, 65–75.
Robinson, R. and Stokes, R. (1959) Electrolyte Solutions: Pitman Press, London.
Valleau, J. P. and Torrie, G. M. (1982) The electrical double layer III. Modified Gouy-Chapman theory with unequal ion sizes: J. Chem. Phys. 76(9), 4623–4630.
Viani, B. E., Low, P. F., and Roth, C. B. (1983) Direct measurement of the relation between interlayer force and interlayer distance in the swelling of montmorillonite: J. Colloid Interface Sci. 96(1), 229–244.
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Huerta, M.M., Curry, J.E. & McQuarrie, D.A. The Effect of Unequal Ionic Size on the Swelling Pressure in Clays. Clays Clay Miner. 40, 491–500 (1992). https://doi.org/10.1346/CCMN.1992.0400502
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DOI: https://doi.org/10.1346/CCMN.1992.0400502