A Molecular Mechanism of Hysteresis in Clay Swelling

Tambach, Tim J.; Bolhuis, Peter G.; Smit, Berend

doi:10.1002/anie.200353612

Cited by 60 publications

(61 citation statements)

References 35 publications

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“…[48][49][50] There is an overall good agreement between the computed and measured data, although the experimental d 001 -spacing values are prone to large uncertainties because the experimental samples were prepared by dehydrating humidity-exposed clays, which may have caused the original structure not to be preserved. 51,52 Figure 3 depicts equilibrated structures of dry Na-MMT at θ = 6°( as an example). The disordering is represented as alternating clay layers rotated around an axis perpendicular to the internal clay surfaces.…”

Section: Enforced Rotationmentioning

confidence: 99%

Molecular Dynamics Simulations of Turbostratic Dry and Hydrated Montmorillonite with Intercalated Carbon Dioxide

et al. 2014

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Molecular dynamics simulations using classical force fields were carried out to study energetic and structural properties of rotationally disordered clay mineral-water-CO 2 systems at pressure and temperature relevant to geological carbon storage. The simulations show that turbostratic stacking of hydrated Na-and Ca-montmorillonite and hydrated montmorillonite with intercalated carbon dioxide is an energetically demanding process accompanied by an increase in the interlayer spacing. On the other hand, rotational disordering of dry or nearly dry smectite systems can be energetically favorable. The distributions of interlayer species are calculated as a function of the rotational angle between adjacent clay layers.

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Section: Enforced Rotationmentioning

confidence: 99%

Molecular Dynamics Simulations of Turbostratic Dry and Hydrated Montmorillonite with Intercalated Carbon Dioxide

et al. 2014

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“…In montmorillonite, each layer is composed of two tetrahedral (T) silica sheets sandwiching one octahedral (O) alumina sheet. 11,14,[16][17][18][19][20][21][22][23] The most studied montmorillonites have been the Wyoming-type, which include two types of substitution: octahedral and tetrahedral (OT sub ), and the Otay-type which comprises only the octahedral substitution (O sub ), see Fig. Depending on the isomorphic substitution (octahedral, tetrahedral or both) we have different kinds of montmorillonites (see Fig.…”

Section: Introductionmentioning

confidence: 99%

Ab initio molecular dynamics study of the hydration of Li+, Na+ and K+ in a montmorillonite model. Influence of isomorphic substitution

Mignon

Ugliengo

Sodupe

et al. 2010

Phys. Chem. Chem. Phys.

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The present work reports ab initio molecular dynamics simulations, based on density functional theory using the PBE functional, of Li(+)- Na(+)- and K(+)-montmorillonites, considering three types of isomorphic substitutions in the montmorillonite layer: tetrahedral (T(sub)), octahedral (O(sub)) and both (OT(sub)). These simulations allow us to evaluate the effect of each type of substitution on the inner- outer-sphere complex formation of the alkali cations. It is observed that, for the three kinds of substituted montmorillonites, K(+) remains bound to the surface confirming its role as swelling inhibitor. In contrast, Li(+) tends to hydrate and coordinate to 4 water molecules in all cases, except for OT(sub), for which one of the two Li(+) cations remains bound to the oxygens close to the substituted tetrahedral site. Finally, Na(+) presents an intermediate behaviour, binding to the surface in T(sub) montmorillonite but being hydrated in O(sub). These simulations show that the hydration/adsorption behaviour of alkali cations in the swelling process of montmorillonite depends on the affinity of the cation for water and the surface, as well as on the type of substitution that controls the negative charge on surface oxygen atoms.

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“…In this case, "crystalline" swelling is observed and water is, for instance, inserted in a well-defined stepwise fashion of discrete numbers of monolayers (1-3 water layers, 1 WL, 2 WL, 3 WL). [7][8] The incremental increase of the basal spacing corresponds to the size of densely packed layers of water molecules (≈ 3 Å at ambient pressure). Hydration/dehydration cycles involve an activation energy and are expected to show hysteresis.…”

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confidence: 99%