Temperature effects on the diffusion of water and monovalent counterions in the hydrated montmorillonite |
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Authors: | Y Zheng A Zaoui |
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Institution: | Laboratoire Génie Civil et Géo-Environnement (LGCgE, EA 4515) Lille Nord de France, Polytech’Lille, Université Lille1 Sciences et Technologie, Cité Scientifique, Avenue Paul Langevin, 59655 Villeneuve D’Ascq Cedex, France |
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Abstract: | We investigate here the effect of temperature on the diffusion of water and cations in the Wyoming-type montmorillonite clay. The considered cations are monovalent compensating ions, such as Li+, Na+, K+, Rb+ and Cs+ in one-, two- and three-hydration states. For this purpose, molecular dynamics simulations have been performed to obtain the dynamic behaviour regarding the interlayer ions and water molecules under a temperature range between 260 and 400 K. The diffusion coefficient of water and cations in different hydrated clays increases with temperature. The influence of temperature on the diffusion of water is much greater than that of cations in one-, two- or three-hydrated clay. The degree of hydration plays an important role on the diffusion behaviour of water and counterions. We found that the effect of temperature is negligible in weakly hydrated clay, whereas it became significant in highly hydrated one. Besides, the size and mass of cations’ hydrate also affect the diffusion behaviour of water and cations in the interlayer space of hydrated clay. |
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Keywords: | Diffusion Water Monovalent cations Montmorillonite Molecular dynamics Temperature effect |
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