Dielectric properties of montmorillonite clay films: Effects of water and layer charge reduction

Bidadi, H.; Schroeder, P. A.; Pinnavaia, Thomas J.

doi:10.1016/0022-3697(88)90117-5

Cited by 27 publications

(8 citation statements)

References 13 publications

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“…The hypothesis of a variable dielectric constant suggested by the present approach seems quite plausible in view of the change in ε r reported for the adsorption of water in microporous clays [27,28] and in particular in expanding montmorillonites [29]. Their structure consists of negatively charged layers with Na + or Ca +2 cations between them, which are solvated by water.…”

Section: Comparison With Models and Possible Consequencessupporting

confidence: 61%

Surface-related capacitance of microporous carbons in aqueous and organic electrolytes

Centeno

Stoeckli

2011

Electrochimica Acta

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This paper examines the surface-related capacitance C/S of carbons with average micropore widths between 0.73 and 1.80 nm, using 1-2M H 2 SO 4 , 6M KOH and 1M (C 2 H 5 ) 4 NBF 4 in acetonitrile as electrolytes. Following corrections for pseudocapacitance effects for the aqueous electrolytes and the use of an average surface area suggested by independent techniques, different from the BET area, it appears that C/S is practically independent of the micropore width.The analysis of the data with the help of recent models suggests that the dielectric constants ε r of the different electrolytes may decrease with the pore size. It is surprising that the coexistence of two sets of values for the surface area of microporous carbons and its consequence on C/S have not received more attention in the past.

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Section: Comparison With Models and Possible Consequencessupporting

confidence: 61%

Surface-related capacitance of microporous carbons in aqueous and organic electrolytes

Centeno

Stoeckli

2011

Electrochimica Acta

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“…When less than three molecular layers of water are present in the interlamellar region, the structure of sorbed water on smectites has been shown to be influenced predominantly by exchangeable cations (Mooney et al, 1952b;Clementz et al, 1973Clementz et al, , 1974Prost, 1975;McBride, 1982;Sposito and Prost, 1982;Sposito et al, 1983;Bidadi et al, 1988;Grandjean and Laszlo, 1989;Kogelbauer et al, 1989;Hall and Astill, 1989;Trillo et aL, 1990;Fu et aL, 1990;Delville et aL, 1991;Tinet et al, 1992). Spectroscopic investigations of smectite-water interactions (Prost, 1975;Sposito and Prost, 1982;Brown and Kevan, 1988;Weiss et al, 1990a;Bank et al, 1991;Tinet et al, 1992) suggest that two distinct environments of sorbed water are present: 1) water molecules coordinated directly to exchangeable metal cations, and 2) physisorbed water molecules occupying interstitial pores, interlameUar spaces between exchangeable metal cations, or polar sites on external surfaces.…”

Section: Introductionmentioning

confidence: 99%

“…On the basis of NMR and ESR (McBride and Mortland, 1974;McBride et aL, 1975;McBride, 1982;Brown and Kevan, 1988;Grandjean and Laszlo, 1989;Kogelbauer et aL, 1989;Delville et al, 1991), complex dielectric permittivity and neutron scattering data (Sposito and Prost, 1982), and other dielectric measurements (Fripiat et al, 1965;Bidadi et al, 1988), water molecules coordinated to metal cations on a clay mineral surface are considered to be in less mobile, Copyright 9 1992, The Clay Minerals Society restricted environments relative m those in bulk water. This molecular picture of coordinated water in the interlamellar region is consistent with vibrational spectroscopic studies of water sorbed on smectites (Farmer, 1978), Russell and Farmer (1964), for example, found that the OH stretching and bending bands in the infrared (IR) spectra of water sorbed on montmorillonite and saponite were perturbed on going from higher to lower hydration states of these smectites.…”

Section: Introductionmentioning

confidence: 99%

Vibrational Probe Studies of Water Interactions with Montmorillonite

Johnston

Sposito

Erickson

1992

Clays and clay miner.

122

114

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Abstract--Imeraction of water with montmorillonite exchanged with Na +, K +, Co 2+, and Cu 2+ cations as a function of water content was examined using an FTIR/gravimetric cell designed to collect spectroscopic and sorption data simultaneously. Correlation of water desorption isotherms with infrared spectra of the clay-water complex showed that the position of the HOH bending band of water decreased as a function of water content. The largest decreases in frequency were observed for Cu 2+ and Co 2 +; smaller decreases were found for Na + and K + . In addition, the molar absorptivity of sorbed water increased upon decreasing the water content. The decrease in frequency and the concomitant increase in molar absorptivity were attributed to polarization effects on the sorbed water molecules by exchangeable cations. The interference fringes of a self supporting clay film permitted d-spacings to be determined optically and, therefore, changes in frequency, molar absorptivity, and water sorption behavior to be related directly to changes in interlayer spacing. The d-spacings obtained from the interference fringes were consistently larger by approximately 0.5 ~ than those determined using powder XRD.

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“…Furthermore, there exists experimental evidence showing that the relative permittivity of an ionic solution in micropores decreases with the solvent to ion ratio. For example, it has been reported that in the case of water filling the micropores of expanding clays 23,24 such as bentonites 25 , ε r decreases as the interlayer spacing decreases. These micropores consist of negatively charged layers with a constant amount of Na + or Ca +2 ions surrounded by a variable amount of water.…”

mentioning

confidence: 99%