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The Polymer Model of Thermochemical Clay Mineral Stability

Published online by Cambridge University Press:  02 April 2024

Garrison Sposito
Garrison Sposito*
Affiliation:
Department of Soil and Environmental Sciences, University of California, Riverside, California 92521
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Abstract

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The Nriagu polymer model of 2:1 layer type clay minerals develops from the premise that clay minerals are condensation copolymers of solid hydroxides. In the Mattigod-Sposito formulation of the model, standard state chemical potentials (standard Gibbs energies of formation from the elements) of 2:1 clay minerals are predicted quantitatively with a linear correlation equation relating the standard Gibbs energy of the polymerization reaction (ΔGor) to the half-cell layer charge of the clay mineral and to the valence and ionic radius of the exchangeable cation. It is now shown that this correlation equation can be derived from two basic assumptions: (1) that the standard Gibbs energy change for the transfer of a cation in a pure hydroxide solid to a hydroxide component in the tetrahedral or octahedral sheet of a 2:1 clay mineral is independent of the nature of the cation and (2) that the difference between ΔGor for the polymerization reaction to form a 2:1 clay mineral and ΔGor for the same reaction to form the zero layer-charge analog of the clay mineral is proportional to the number of interlayer exchangeable cations per unit cell of the clay mineral and to the radius of its exchangeable cation. Both of these assumptions can be tested experimentally, independent of the polymer model.

Keywords

Chemical potentialIlliteLayer chargePolymer modelSmectiteStabilityVermiculite
Type
Research Article
Information
Clays and Clay Minerals , Volume 34 , Issue 2 , April 1986 , pp. 198 - 203
Copyright
Copyright © 1986, The Clay Minerals Society

References

Aagaard, P. and Helgeson, H. C., 1983 Activity/composition relations among silicates and aqueous solutions: II. Chemical and thermodynamic consequences of ideal mixing of atoms on homological sites in montmorillonites, illites, and mixed-layer clays Clays & Clay Minerals 31 207–217.CrossRefGoogle Scholar
Ahrens, L. H., 1983 Ionization Potentials Oxford Pergamon Press.Google Scholar
Chen, C.-H., 1975 A method of estimation of standard free energies of formation of silicate minerals at 298.15°K Amer. J. Sci. 275 801–817.CrossRefGoogle Scholar
Gresens, R. L., 1981 The aqueous solubility product of solid solutions. 1. Stoichiometric saturation; partial and total solubility product Chem. Geol. 32 59–72.CrossRefGoogle Scholar
Huheey, J. E., 1972 Inorganic Chemistry New York Harper and Row.Google Scholar
Lippmann, F. and Konta, J., 1981 Stability diagrams involving clay minerals 8th Conf. Clay Mineral. Petrol., Teplice, 1979 Prague Univ. Carolinae Prag. 153–171.Google Scholar
Lippmann, F., van Olphen, H. and Veniale, F., 1982 The thermodynamic status of clay minerals Proc. Intl. Clay Conf., Bologna, Pavia, 1981 Amsterdam Elsevier 475–485.Google Scholar
Mattigod, S. V. and Sposito, G., 1978 Improved method for estimating the standard free energies of formation (AG°f298.15) of smectites Geochim. Cosmochim. Acta 42 1753–1762.CrossRefGoogle Scholar
Misono, M., Ochai, E., Saito, Y. and Yoneda, Y., 1967 A new dual parameter scale for the strength of Lewis acids and bases with the evaluation of their softness J. Inorg. Nucl. Chem. 29 2685–2691.CrossRefGoogle Scholar
Nriagu, J. O., 1975 Thermochemical approximations for clay minerals Amer. Mineral. 60 834–839.Google Scholar
Pauling, L., 1960 The Nature of the Chemical Bond: Cornell New York Univ. Press, Ithaca.Google Scholar
Robie, R. A., Hemingway, B. S., and Fisher, J. R. (1978) Thermodynamic properties of minerals and related substances at 298.15 K and 1 bar (105 Pascals) pressure and at higher temperatures: U.S. Geol. Survey Bull. 1452, 456 pp.Google Scholar
Shannon, R. D. and Prewitt, C. T., 1969 Effective ionic radii in oxides and fluorides Acta Crystallogr. B25 925–946.CrossRefGoogle Scholar
Sposito, G., 1981 The Thermodynamics of Soil Solutions Oxford Oxford Univ. Press.Google Scholar
Sposito, G., 1984 The Surface Chemistry of Soils New York Oxford Univ. Press.Google Scholar
Sposito, G. and Drever, J. I., 1985 Chemical models of weathering in soils Chemistry of Weathering Netherlands D. Reidel, Dordrecht 1–18.Google Scholar
Stoessell, R. K., 1979 A regular solution site-mixing model for illites Geochim. Cosmochim. Acta 43 1151–1159.CrossRefGoogle Scholar
Stoessell, R. K., 1981 Refinements in a site-mixing model for illites: local electrostatic balance and the quasi-chemical approximation Geochim. Cosmochim. Acta 45 1733–1741.CrossRefGoogle Scholar
Tardy, Y. and Fritz, B., 1981 An ideal solution model for calculating solubility of clay minerals Clay Miner. 16 361–373.CrossRefGoogle Scholar
Tardy, Y. and Garrels, R. M., 1974 A method of estimating the Gibbs energies of formation of layer silicates Geochim. Cosmochim. Acta 38 1101–1116.CrossRefGoogle Scholar
Wagman, D. D., Evans, W. H., Parker, V. B., Schumm, R. H., Halow, I., Bailey, S. M., Churney, K. L. and Nuttall, R. L., 1982 The NBS tables of chemical thermodynamic properties J. Phys. Chem. Ref. Data 11 Suppl.2 1–392.Google Scholar
Weaver, C. E. and Pollard, L. D., 1973 The Chemistry of Clay Minerals Amsterdam Elsevier.Google Scholar

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