Molecular dynamics computer simulations of the effects of hydrogen bonding on the properties of layered double hydroxides intercalated with organic acids

Kalinichev, Andrey G.; Kumar, P. Padma; Kirkpatrick, R. James

doi:10.1080/14786430903559482

Cited by 56 publications

(65 citation statements)

References 57 publications

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“…In order to quantify the thermodynamics of hydration and swelling for three different Cs−montmorillonite models, we calculated the hydration energy, immersion energy, 27,36,40,41,[96][97][98]100 and the isosteric heat of adsorption 27 at each of the hydration states. The hydration energy (ΔU) evaluates the energy change associated with water uptake by the dry clay, and can be calculated using the generic formula:…”

Section: +mentioning

confidence: 99%

Structural Arrangements of Isomorphic Substitutions in Smectites: Molecular Simulation of the Swelling Properties, Interlayer Structure, and Dynamics of Hydrated Cs–Montmorillonite Revisited with New Clay Models

2014

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Three new structural models of montmorillonite with differently distributed Al/Si and Mg/Al substitutions in the tetrahedral and octahedral clay layers are systematically developed and studied by means of MD simulations to quantify the possible effects of such substitutional disorder on the swelling behavior, the interlayer structure, and mobility of aqueous species. A very wide range of water content, from 0 to 700 mg water /g clay is explored to derive the swelling properties of Cs−montmorillonite. The determined layer spacing does not differ much depending on the clay model. However, at low water contents up to 1-layer hydrate (∼100 mg water /g clay ) the variation of specific locations of the tetrahedral and octahedral substitutions in the two TOT clay layers slightly but noticeably affects the total hydration energy of the system. Using atom−atom radial distribution functions and the respective atomic coordination numbers we have identified for the three clay models not only the previously observed binding sites for Cs + on the clay surface but also new ones that are correlated with the position of tetrahedral substitution in the structure. The mobility of Cs + ions and H 2 O diffusion coefficients, as expected, gradually increase both with increasing water content and with increasing distance from the clay surface, but they still remain 2 to 4 times lower than the corresponding bulk values. Only small differences were observed between the three Cs− montmorillonite models, but these differences are predicted to increase in the case of higher charge density of the clay layers and/or interlayer cations.

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Section: +mentioning

confidence: 99%

Structural Arrangements of Isomorphic Substitutions in Smectites: Molecular Simulation of the Swelling Properties, Interlayer Structure, and Dynamics of Hydrated Cs–Montmorillonite Revisited with New Clay Models

2014

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“…This ion has a comparable ionic size with K + and can easily substitute for K + in the muscovite mica and other K-bearing phyllosilicates [32]. Ammonium is an important cationic functional group present in many polymers and other organic molecules, which is responsible for their strong interactions with clays and clay-related mineral surfaces [27,33] and for the formation of many useful organo-inorganic nanocomposites for diverse technological and environmental applications.…”

Section: Introductionmentioning

confidence: 99%

On the Hydrogen Bonding Structure at the Aqueous Interface of Ammonium-Substituted Mica: A Molecular Dynamics Simulation

Loganathan

2013

Zeitschrift Für Naturforschung A

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Dedicated to Professor Alfred Klemm on the occasion of his 100th birthday.Molecular dynamics (MD) computer simulations were performed for an aqueous film of 3 nm thickness adsorbed at the (001) surface of ammonium-substituted muscovite mica. The results provide a detailed picture of the near-surface structure and topological characteristics of the interfacial hydrogen bonding network. The effects of deuterium/hydrogen isotopic substitution in N(H/D) 4 + on the dynamics and consequently on the convergence of the structural properties have also been explored. Unlike many earlier simulations, a much larger surface area representing 72 crystallographic unit cells was used, which allowed for a more realistic representation of the substrate surface with a more disordered distribution of aluminium/silicon isomorphic substitutions in muscovite. The results clearly demonstrate that under ambient conditions both interfacial ammonium ions and the very first layer of water molecules are H-bonded only to the basal surface of muscovite, but do not form H-bonds with each other. As the distance from the surface increases, the H-bonds donated to the surface by both N(H/D) 4 + and H 2 O are gradually replaced by the H-bonds to the neighbouring water molecules, with the ammonia ions experiencing one reorientational transition region, while the H 2 O molecules experiencing three such distinct consecutive transitions. The hydrated N(H/D) 4 + ions adsorb almost exclusively as inner-sphere surface complexes with the preferential coordination to the basal bridging oxygen atoms surrounding the aluminium/silicon substitutions.

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“…33 In addition, we analysed the H-bond network within the interlayer galleries and at the clay surface by applying a commonly used geometric criteria of an H-bond, 34 previously employed for hydrated layered systems. 35,36 The geometric criteria assume that a H-bond exists if and only if the intermolecular O· · · H distance is less than 2.45 Å and the angle between the O· · · O and O-H vectors is less than 30 • . In the evaluation of the H-bond network, the oxygen atoms of the clay surface, O b , were treated in the same way as O w , i.e., as potential H-bond acceptors.…”

Section: Computational Detailsmentioning

confidence: 99%

Concentrated aqueous sodium chloride solution in clays at thermodynamic conditions of hydraulic fracturing: Insight from molecular dynamics simulations

Svoboda

Lı́sal

2018

The Journal of Chemical Physics

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A relationship between the effect of uni-univalent electrolytes on the structure of water and on its volatility The Journal of Chemical Physics 148, 222807 (2018) To address a high salinity of flow-back water during hydraulic fracturing, we use molecular dynamics (MD) simulations and study the thermodynamics, structure, and diffusion of concentrated aqueous salt solution in clay nanopores. The concentrated solution results from the dissolution of a cubic NaCl nanocrystal, immersed in an aqueous NaCl solution of varying salt concentration and confined in clay pores of a width comparable to the crystal size. The size of the nanocrystal equals to about 18 Å which is above a critical nucleus size. We consider a typical shale gas reservoir condition of 365 K and 275 bar, and we represent the clay pores as pyrophyllite and Na-montmorillonite (Na-MMT) slits. We employ the Extended Simple Point Charge (SPC/E) model for water, JoungCheatham model for ions, and CLAYFF for the slit walls. We impose the pressure in the normal direction and the resulting slit width varies from about 20 to 25 Å when the salt concentration in the surrounding solution increased from zero to an oversaturated value. By varying the salt concentration, we observe two scenarios. First, the crystal dissolves and its dissolution time increases with increasing salt concentration. We describe the dissolution process in terms of the number of ions in the crystal, and the crystal size and shape. Second, when the salt concentration reaches a system solubility limit, the crystal grows and attains a new equilibrium size; the crystal comes into equilibrium with the surrounding saturated solution. After crystal dissolution, we carry out canonical MD simulations for the concentrated solution. We evaluate the hydration energy, density profiles, orientation distributions, hydrogen-bond network, radial distribution functions, and in-plane diffusion of water and ions to provide insight into the microscopic behaviour of the concentrated aqueous sodium chloride solution in interlayer galleries of the slightly hydrophobic pyrophyllite and hydrophilic Na-MMT pores. Published by AIP Publishing. https://doi

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Molecular dynamics computer simulations of the effects of hydrogen bonding on the properties of layered double hydroxides intercalated with organic acids

Cited by 56 publications

References 57 publications

Structural Arrangements of Isomorphic Substitutions in Smectites: Molecular Simulation of the Swelling Properties, Interlayer Structure, and Dynamics of Hydrated Cs–Montmorillonite Revisited with New Clay Models

Structural Arrangements of Isomorphic Substitutions in Smectites: Molecular Simulation of the Swelling Properties, Interlayer Structure, and Dynamics of Hydrated Cs–Montmorillonite Revisited with New Clay Models

On the Hydrogen Bonding Structure at the Aqueous Interface of Ammonium-Substituted Mica: A Molecular Dynamics Simulation

Concentrated aqueous sodium chloride solution in clays at thermodynamic conditions of hydraulic fracturing: Insight from molecular dynamics simulations

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