Charge location effect on the hydration properties of synthetic saponite and hectorite saturated by Na+, Ca2+ cations: XRD investigation

Karmous, Mohamed Salah; Rhaïem, H. Ben; Robert, Jean-Louis; Lanson, Bruno; Amara, Abdesslem Ben Haj

doi:10.1016/j.clay.2009.07.007

Cited by 30 publications

(32 citation statements)

References 25 publications

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“…Also, an increase in the saponite layer charge enhances the interlayer hydration . Karmous et al (2009) conducted hydration experiments at standard pressure and temperature by forcing the relative humidity (90 %) on saponites similar to those considered (i.e., the same layer charge). His results indicate the incorporation of two layers of water, leading to a potential maximal expansion of the basal spacing at 16.32 Å when Ca is in the interlayer sheet, and 14.99 Å when Na is in the interlayer sheet.…”

Section: Geochemical Model Setupmentioning

confidence: 99%

Differential alteration of basaltic lava flows and hyaloclastites in Icelandic hydrothermal systems

2015

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Geological field observations evidence that active and fossil Icelandic hydrothermal systems are typically embedded into an intercalation of almost completely altered and nearly unaltered volcanic rock layers. We investigated the reasons for this finding with help of geochemical reaction path calculations, by studying the mineralogical evolution of contrasting lithofacies-basalt flows and hyaloclastites at various temperatures and pressures, different recharge water composition, and gas content. From this study, we conclude that the initial porosity of protoliths and volume changes due to their transformation into secondary minerals are sufficient to explain the different extents of alteration as observed in field studies. In addition, we present a generalized kinetic model to estimate the alteration time of glassy fragments in hyaloclastite as a function of grain size, surface roughness, and temperature. This time was found to be rather short, ranging from a few hours to a few years.

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Section: Geochemical Model Setupmentioning

confidence: 99%

Differential alteration of basaltic lava flows and hyaloclastites in Icelandic hydrothermal systems

2015

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“…X-ray diffraction (XRD) experiments have been applied for investigating the interlayer cation states via a variation of the basal spacing upon hydration. [10][11][12] The uniform distribution of interlayer cations without any specific structure has been implied in the previous studies. In the present study, the interlayer cation states, which can be varied via the local structure of the 2D nanosheets, were highlighted based on the data of solid-state 23 Na nuclear magnetic resonance (NMR) spectroscopy.…”

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confidence: 67%

Tunable states of interlayer cations in two-dimensional materials

Sato

Numata

Dai

et al. 2014

Applied Physics Letters

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Structural response of a highly viscous aluminoborosilicate melt to isotropic and anisotropic compressionsThe local state of cations inside the Å ngstrom-scale interlayer spaces is one of the controlling factors for designing sophisticated two-dimensional (2D) materials consisting of 2D nanosheets. In the present work, the molecular mechanism on how the interlayer cation states are induced by the local structures of the 2D nanosheets is highlighted. For this purpose, the local states of Na cations in inorganic 2D materials, in which the compositional fluctuations of a few percent are introduced in the tetrahedral and octahedral units of the 2D nanosheets, were systematically studied by means of 23 Na magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) and 23 Na multiple-quantum MAS (MQMAS) NMR spectroscopy. In contrast with an uniform distribution of Na cations expected so far, various well-defined cation states sensitive to the local structures of the 2D nanosheets were identified. The tunability of the interlayer cation states along with the local structure of the 2D nanosheets, as the smallest structural unit of the 2D material, is discussed. V C 2014 AIP Publishing LLC. [http://dx.

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“…These negative charges in MMT surface come from the isomorphic substitution that is the replacement of Al 3+ by other divalent cations like Mg 2+ and Fe 2+ in the octahedral sheet or the replacement of Si 4+ by Al 3+ in the tetrahedral sheet of the MMT layer. Previous works28–30 demonstrated that surface charge density of clay layers and charge locations were crucial to the swelling and flocculation of the clay platelets and the clay/water interactions. Currently, we believe it is quite possible that for the natural MMT minerals, due to the wide distribution of the local surface charge density, not all MMT platelets exfoliated into monolayers when dispersed in water; some stacked structure with very less MMT layers might still be there in the aqueous suspension, which is hard to be tested by instruments.…”

Section: Resultsmentioning

confidence: 98%

Preparing Exfoliated MMT/Polymer Nanocomposites by Combined Latex Compounding and Spray‐Drying

Lü

Wang

et al. 2011

Macro Materials & Eng

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A facile and easily industrialized approach for preparing highly dispersed MMT/polymer nanocomposites is developed by combining the latex compounding method and a spray‐drying process. Clay particles are successfully delaminated into layers, and layer re‐stacking is effectively prevented. HR‐TEM and XRD results confirm that MMT layers achieve exfoliated or nearly exfoliated dispersion in both MMT/styrene‐butadiene rubber and MMT/PS nanocomposites. Compared with melt‐blended MMT/SBR composites, MMT/SBR nanocomposites prepared by this new strategy exhibit extremely high dynamic modulus.magnified image

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Charge location effect on the hydration properties of synthetic saponite and hectorite saturated by Na+, Ca2+ cations: XRD investigation

Cited by 30 publications

References 25 publications

Differential alteration of basaltic lava flows and hyaloclastites in Icelandic hydrothermal systems

Differential alteration of basaltic lava flows and hyaloclastites in Icelandic hydrothermal systems

Tunable states of interlayer cations in two-dimensional materials

Preparing Exfoliated MMT/Polymer Nanocomposites by Combined Latex Compounding and Spray‐Drying

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