Computer simulation of alkali metal cation-montmorillonite hydrates
- Columbia Univ., Palisades, NY (United States)
- Univ. College, London (United Kingdom)
- Lawrence Berkeley National Lab., CA (United States)
Molecular structure in the interlayers of Li-, Na-, or K-Wyoming montmorillonite with one, two, or three adsorbed water layers was investigated for the first time by concurrent Monte Carlo and molecular dynamics (MD) simulation, based on the Matsouka-Clementi-Yoshimine, (MCY) model of water-water interactions. Calculated layer spacings, as well as interlayer-species self-diffusion coefficients, were in good agreement with available experimental data. Inner-sphere surface complexes of the cations with tetrahedral charge sites were observed for all hydrates, whereas outer-sphere surface complexes of the cations with octahedral charge sites, found also in the one-layer hydrate, tended to dissociate from the clay mineral basal planes into a diffuse layer in the two- and three-layer hydrates. Differences in the interlayer water structure among the hydrates mainly reflected cation solvation, although some water molecules were entrapped within cavities in the montmorillonite surface. All of the interlayer cation and water species exchanged on the time scale (0.2 ns) of the MD simulations. Comparisons with results obtained using, instead of the MCY model, the TIP4P model for water-water, cation-water, and cation-clay interactions indicated that layer spacings and interlayer species mobilities tend to be under-predicted by the TIP4P model.
- OSTI ID:
- 560033
- Report Number(s):
- CONF-970443-; TRN: 97:005895-0108
- Resource Relation:
- Conference: 213. national meeting of the American Chemical Society, San Francisco, CA (United States), 13-17 Apr 1997; Other Information: PBD: 1997; Related Information: Is Part Of 213th ACS national meeting; PB: 2904 p.
- Country of Publication:
- United States
- Language:
- English
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