Crystalline Swelling of Smectite Samples in Concentrated NaCl Solutions in Relation to Layer Charge

Slade, P. G.; Quirk, J. P.; Norrish, K.

doi:10.1346/ccmn.1991.0390302

Cited by 143 publications

(76 citation statements)

References 20 publications

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“…Jaynes et al (1992) reported a decrease in the negative layer charge in Mghectorites after each of several heat treatments at 250~ which was attributed to progressive octahedral Mg > for Li + substitution. Slade et al (1991) found that the basal spacing of hectorite expanded from 15.5 .~ to 18.5 A in NaC1 solutions as the NaC1 concentration decreased, corresponding to the transition from two to three sheets of water between the silicate layers. This behavior is typical of most montmorillonites.…”

Section: Introductionmentioning

confidence: 96%

Dissolution of Hectorite in Inorganic Acids

Komadel

1996

Clays and clay miner.

105

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Abstract--The effect of acid type and concentration on the reaction rate and products of dissolution of hectorite in inorganic acids was investigated. The dissolution of hectorite in hydrochloric (HC1), nitric (HNO3) and sulphuric (H2SO4) acids was characterized using quantitative chemical analysis, infrared (IR) and multinuclear MAS NMR spectroscopies. The rate of dissolution increased with acid concentration and decreased in the order HC1 --> HNO 3 > H2SO 4 at the same molar concentration. No differences were found in the reaction products of hectorite treated with the three acids. The rate of Li dissolution was slightly greater than that of Mg at lesser acid concentrations (0.25 M), indicating that protons preferentially attack Li octahedra. The gradual changes in the Si-O IR bands reflects the extent of hectorite dissolution. The analysis of 298i MAS NMR spectra relative peak intensities with dissolution time and acid concentration provided direct dissolution rates for tetrahedral (Q3) Si. After acid dissolution, most Si was bound in a three dimensional framework site (Q4), but a substantial part also occurred in the Si(OSi)3OH (Q31 OH) and Si(OSi)2(OH)2 (Q22OH) environments. These three sites probably occur in a hydrous amorphous silica phase. Both Aliv and Alw rapidly disappeared from 27A1 MAS NMR spectra of the dissolution products with acid treatment. The changes in IR and MAS NMR spectra of hectorite due to acid dissolution are similar to those of montmorillonite.

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Section: Introductionmentioning

confidence: 96%

Dissolution of Hectorite in Inorganic Acids

Komadel

1996

Clays and clay miner.

105

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“…The equilibrium water density of such a hydrated clay depends on the type of clay mineral, the type of interlayer counterion, the applied pressure and temperature, and the water vapor pressure. [3][4][5][6] Although clay swelling is well understood on a qualitative level, the quantitative details are difficult to access experimentally, especially on the molecular level. Statisticalmechanical computer simulations are ideally suited to obtain such microscopic insight.…”

Section: Introductionmentioning

confidence: 99%

Adsorption isotherms of water in Li–, Na–, and K–montmorillonite by molecular simulation

Hensen

Tambach

Bliek

et al. 2001

The Journal of Chemical Physics

102

133

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A biased Monte Carlo method for the insertion of water in dense clay-water systems is presented. The use of this algorithm results in a considerable increase of the success rate of insertion attempts. It allows us to compute water adsorption isotherms up to high water densities, where the conventional Monte Carlo scheme fails. The isotherms were calculated by a combination of molecular dynamics and grand-canonical Monte Carlo simulation for Li-, Na-, and Kmontmorillonite at a fixed d(001) spacing of 12.0 Å. At low water pressure, the degree of clay hydration is governed by the type of counterion, Li-montmorillonite having the highest water content. Hydrogen bonding between water molecules is absent. Li ϩ and Na ϩ are small enough to be organized in two layers close to the clay mineral surfaces, whereas K ϩ is mainly located in the midplane. In both cases, the water molecules primarily reside in the midplane of the interlayer. Increasing the water pressure leads to water adsorption at higher energy sites closer to the surface, i.e., coordinating to the structural OH groups in the hexagonal cavities. A hydrogen bond network is formed in the clay interlayer. This points to water condensation and leads to a sharp increase in the clay water content.

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“…Various techniques such as NMR, IR and X-ray scattering have been used to determine the ordering and mobility of the water molecules in the layers (Nickolov et al, 2005;Pouliquen et al, 2001;Slade et al, 1991;Turov et al, 2005). Molecular dynamics simulation that combines physics, mathematics and chemistry is an advanced research method to study the radial distribution of water molecules around particles.…”

Section: Methodsmentioning

confidence: 99%

Hydration Layers on Clay Mineral Surfaces in Aqueous Solutions: a Review/Warstwy Uwodnione Na Powierzchni Minerałów Ilastych W Roztworach Wodnych: Przegląd

Min¹,

Peng²,

Song³

2014

Archives of Mining Sciences

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Hydration layer on clay mineral surfaces is originated from the adsorption of polar water molecules and hydrated cations on the surfaces through unsaturated ionic bonds, hydrogen bonds and van der Waals bonds. It has attracted great attentions because of their important influences on the dispersive stability of the particles in aqueous solutions. This review highlighted the molecular structure of clay minerals, the origin of hydration layers on clay mineral surfaces, the hydration layer structural model, hydration force and the main parameters of affecting the hydration layers on clay minerals (crystal structure, cationic type and strength, and solution pH). Also, the research methods for hydration layers were briefly described, especially the determination of hydration layer thickness by the Einstein viscosity method and AFM method. In addition, the applications of the stability of fine clay mineral particles in aqueous suspensions were summarized.Keywords: Hydration layers; clay minerals; dispersion; hydration force Warstwa uwodniona na powierzchni minerałów ilastych (gliniastych) powstaje w wyniku adsorpcji polarnych cząsteczek wody i uwodnionych kationów powierzchniowych wiązanych za pomocą nienasyconych wiązań jonowych, wiązań wodorowych i wiązań van der Waalsa. Zagadnienie to wzbudza wiele uwagi ze względu na to, że w dużej mierze warunkuje stabilność dyspersyjną cząstek w roztworach wodnych. W pracy omówiono strukturę molekularną minerałów ilastych, powstawanie warstw uwodnionych na powierzchni minerałów ilastych i siły hydratacji; przedstawiono także model strukturalny warstwy uwodnionej oraz główne parametry warunkujące powstawanie warstwy uwodnionej na powierzchni materiałów ilastych (struktura krystaliczna, rodzaj występujących kationów, stężenie roztworu i jego pH). Ponadto, pokrótce przedstawiono metody badań, ze szczególnym uwzględnieniem badania grubości warstw uwodnionych przy zastosowaniu modelu lepkości Einsteina oraz metody AFM. Ponadto, zestawiono zagadnienia związane ze stabilnością cząstek drobnoziarnistych minerałowa ilastych i ich potencjalne zastosowania.Słowa kluczowe: warstwy uwodnione, minerały ilaste, dyspersja, siła hydratacji

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Crystalline Swelling of Smectite Samples in Concentrated NaCl Solutions in Relation to Layer Charge

Cited by 143 publications

References 20 publications

Dissolution of Hectorite in Inorganic Acids

Dissolution of Hectorite in Inorganic Acids

Adsorption isotherms of water in Li–, Na–, and K–montmorillonite by molecular simulation

Hydration Layers on Clay Mineral Surfaces in Aqueous Solutions: a Review/Warstwy Uwodnione Na Powierzchni Minerałów Ilastych W Roztworach Wodnych: Przegląd

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