Water and ions in clays : Unraveling the interlayer/micropore exchange using molecular dynamics
Résumé
We present the first microscopic description of the exchange of water and ions between clay interlayers and microporosity. A force field based on Ab-Initio calculations is developed and used in classical Molecular Dynamics simulations. The latter allow to compute the Potential of Mean Force for the interlayer/micropore exchange for water, Na + and Cs + cations, and Cl − anions. For the simulated water content (water bilayer, with interlayer spacing 15.4 ˚ A) and salt concentration in the micropore (0.52 mol.dm −3) the exchange is found to be almost not activated for water and cations, whereas the entrance of an anion into the interlayer is strongly unfavorable (∆F ∼ 9k B T). Calculations of the diffusion tensor in the interlayer and in the micropore complete the study of the exchange dynamics.
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Rotenberg et al. - 2007 - Water and ions in clays Unraveling the interlayer.pdf (1.33 Mo)
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