Application of Double-Layer Theories to the Extensive Crystalline Swelling of Li-Montmorillonite

James Quirk, S. Marcelja

    Research output: Contribution to journalArticle

    46 Citations (Scopus)

    Abstract

    We have used the Poisson-Boltzmann (PB) theory and DLVO double-layer theory together with the hypernetted chain formalism based on the primitive model for electrolyte solutions to examine recently published results for extensive crystalline swelling of Li-montmorillonite as revealed by d(001) spacings over the pressure range 0.05-0.9 MPa and the concentration range 1-10(-4) M LiCl. The analysis based on Langmuir's use of elliptical integrals reveals that the theory satisfactorily predicts surface separation over the range 18-120 Angstrom and that the DLVO theory, with a 5.5 Angstrom Stern layer, indicates Gouy plane potentials ranging from -58 to -224 mV over the concentration range 0.1-10(-4) M LiCl and a constant Gouy plane charge of 0.038 Cm-2, which is 30% of the crystal lattice charge. The anisotropic hypernetted chain (HNC) analysis, also based on lattice charge, satisfactorily predicts pressure-distance relationships over the range of concentrations. There is no evidence for the operation of the ''secondary hydration force'' at a surface separation of 18 Angstrom.
    Original languageEnglish
    Pages (from-to)6241-6248
    JournalLangmuir
    Volume13
    DOIs
    Publication statusPublished - 1997

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