Conduction and diffusion in exchanged montmorillonite clays

Slade, Robert C. T.; Barker, Jeremy; Hirst, Paul R.; Halstead, T. K.; Reid, P.

doi:10.1016/0167-2738(87)90135-4

Cited by 48 publications

(39 citation statements)

References 18 publications

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“…The calculated diffusivities span the range from 10-12-10 -13 m2/s, i.e. 10-8-10 -9 cm2/s, considerably smaller than values determined by quasi-elastic neutron scattering (Hall, 1981;Tuck et al, 1985) or NMR (Fripiat, 1980;Slade et al, 1987). In the present experiments, although the average drainage direction of fluid was perpendicular to the plane of compaction, the assumption of a strongly ordered parallel platelet structure implies that water flows mostly in a direction parallel to platelet faces.…”

Section: S2(eo El) = 2 (~O (Eo -E)d(e) Dementioning

confidence: 99%

Influence of potassium concentration on the swelling and compaction of mixed (Na,K) ion-exchanged montmorillonite

et al. 1991

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A B S T R A C T: Oedometer swelling and compaction tests up to a maximum pressure of 32 bars were made on the Wyoming montmorillonite SWy-1 with a range of mixed (Na,K) exchange ion compositions. The permeabilities and water diffusivities of the compacted clays were calculated using soil physics theory. Significant inhibition of swelling from that of the Na-montmorillonite is developed for K fractions in the range 0.30 < K + < 0.56. However, the water diffusivity increases by a factor of approximately six as the K exchange fraction increases from 0 to 0-7. Permeabilities to water flow show a power-law dependence on the void ratio e.XRD measurements at controlled humidity yield equilibrium interlayer spacings which in general increase with both increasing relative humidity and increasing Na exchange fraction. The extent of swelling is strongly inhibited in clays having Na exchange fractions of 0.44 or less, in good agreement with the oedometer studies.

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Section: S2(eo El) = 2 (~O (Eo -E)d(e) Dementioning

confidence: 99%

Influence of potassium concentration on the swelling and compaction of mixed (Na,K) ion-exchanged montmorillonite

et al. 1991

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“…The mechanism, as it was explained by Slade [1] and Poinsignon [3], is confined to the surface of the 2:1 unit layer.…”

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confidence: 99%

“…Regardless of the attention attracted on montmorillonite as solid electrolyte, its electrical properties in itself deserve to be studied. Among the electrical properties already studied is the conductivity on compacted tablets of purified homoionic montmorillonites (from different origins) after removal of impurities such as quartz and feldspar and free of electrolytes, at the under saturation domain (p/p 0 < 1) [1][2][3][4][5][6][7][8][9]. The authors concluded that the conductivity was mainly due to the transport of charge via protons.…”

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confidence: 99%

“…Electric conductivity of montmorillonites via protons (also known as protonic conductivity) was explained by Slade [1] and Poinsignon [3] with a mechanism where the released protons are propelled by water molecules on the surface of the 2:1 unit layers through two rotational motions: (a) rotation of the hydrate of the cation around the c-axis on the hexagonal hole of the clay layer and (b) rotation of the water molecules of the hydrate, and a translational jump of about 2.8 Å. The mechanism, as it was explained by Slade [1] and Poinsignon [3], is confined to the surface of the 2:1 unit layer.…”

mentioning

confidence: 99%

“…This clay which is widely used in the industry and plays an important role on the physicochemical properties of soils has also been studied as solid electrolyte [1][2][3][4][5][6]. Regardless of the attention attracted on montmorillonite as solid electrolyte, its electrical properties in itself deserve to be studied.…”

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On the Electric Conductivity of Homoionic Montmorillonites at Low Water Content

García¹

2016

JESE-B

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Bibliographic reports on the electric conductivity of pure homoionic montmorillonite at low water content were analyzed in order to stress a general behavior of conductivity. At low water content, the conductivity is attributed to a mechanism of charge transport involving protons due to the influence of the electric field of the exchangeable cations on water molecules at the solvation shell. Conductivity was analyzed in relation with the polarizing power (ionic potential) of the exchangeable cations and with the influence of the connectivity within samples. The general conclusion stressed is that the connectivity due to the association between 2:1 unit layers (clay fabric) is the main factor on the experimental or "macroscopic" electric conductivity of pure homoionic montmorillonite at low water content. Considerations on the experimental conditions of different bibliographic reports were also made. The conclusion and the considerations made on experimental conditions are a good starting point for future researches on electric conductivity of homoionic montmorillonite at low water content.

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New polyelectrolyte materials based on smectite polyoxyethylene intercalation compounds

Aranda

Ruiz‐Hitzky

1994

Acta Polymerica

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The intercalation of poly(ethy1ene oxide), PEO, into homoionic phyllosilicates of the smectite group (montmorillonite and hectorite) gives composite materials able to act as solid polyelectrolytesThe synthesis and the structural characterization of new intercalation compounds belonging to this class of materials have been investigated.The resulting compounds exhibit good chemical and thermal stability, preserving their ion-exchange properties. PEO intercalation produces an enhancement of the electrical conductivity associated with the interlayer cations compared to the parent silicates. Ionic conductivity determined by impedance spectroscopy measurements of different polyoxyethylene compounds (PEO and crown-ethers) into homoionic 2: 1 charged phyllosilicates reveals that the conductivity values can be correlated with the oxyethylene-cation strength interaction.Aranda, Ruiz-Hitzky Acta Polymer., 45, 59-67 (1994)

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Conduction and diffusion in exchanged montmorillonite clays

Cited by 48 publications

References 18 publications

Influence of potassium concentration on the swelling and compaction of mixed (Na,K) ion-exchanged montmorillonite

Influence of potassium concentration on the swelling and compaction of mixed (Na,K) ion-exchanged montmorillonite

On the Electric Conductivity of Homoionic Montmorillonites at Low Water Content

New polyelectrolyte materials based on smectite polyoxyethylene intercalation compounds

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