Gas Chromatographic, <i>Ab Initio</i> and Molecular Statistical Study of the Cluster Adsorption of Water and Methanol Molecules onto Lyophilic Centres on a Generally Lyophobic Adsorbent Surface

Tarasevich, Yu. I.; Aksenenko, E. V.; Zhukova, A. I.; Бондаренко, С. В.

doi:10.1260/026361708786035396

Cited by 3 publications

(1 citation statement)

References 12 publications

(6 reference statements)

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“…Since ab initio calculations of clusters, modeling the systems consisting of octadecylammonium ions and octadecylamine molecules, was not possible because of limitations in resources for calculation, the effect of increasing the length of the alkyl chain on the characteristics of the molecular system was studied. We have used this approach previously in the investigation of the adsorption of water molecules on the surface carboxyl groups of graphite [11]. With this objective we carried out calculations on isolated alkylammonium ions and alkylamine molecules, and also alkylamine-alkylammonium complexes with one, two, and three carbon atoms in the alkyl chain.…”

Section: Modelling Of the Section Of The Modified Layer Containing Thmentioning

confidence: 99%

Ab initio calculation of the hydration of organic cations and their associates with amines on the surface of kaolinite

2009

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It was shown, by ab initio calculations of the characteristics of hydrophilic centers formed on the surfaces of organosubstituted kaolinites with equivalent and superequivalent modifications, that superequivalent modifications of the mineral surface with octadecylammonium chloride, i.e. blocking the hydrophilic centers of the ionic-adsorbed cationic surface-active substance with the molecular adsorbed amine, led to the redistribution of the electron density close to these centers, in particular to the decrease in the effective charge at the hydrophilic centers. The calculated structures and energetics of nanostructures formed by the adsorption of water molecules at such hydrophilic centers showed that such redistribution decreases the energy of their interaction with water, which resulted from theoretical decrease in the energetic effects of hydration of the centers effectively agreed with the experimental values of the heats of adsorption. It was shown that for such adsorbtion systems the energetics were suitable for the formation in the region of the adsorption centers of cyclic structures of water.At present layered silicates are widely used as model materials for theoretical-experimental colloid chemical and adsorption studies [1, 2]. Among a large group of structurally and chemically diverse layered silicates kaolinites are of particular importance to researchers because of their strong structural lattices in which oxysilicon tetrahedral frameworks are linked to octahedral aluminium-oxy-hydroxy networks. A characteristic example of this group of minerals is kaolinite of the Glukhov (Ukraine) deposit which has an entended (~70 m 2 /g) specific surface and a considerable cation exchange volume (~0.25 mg-equiv/g) resulting from non-stoichiometric isomorphous replacement (commonly Mg 2+ ® Al 3+ ) in octahedral positions.Substitution of the natural calcium and sodium exchange complex of kaolinite with long chain alkylammonium cations leads to hydrophobization of the adsorbent. A characteristic of cationic surfactants of alkylammonium or alkylpyridinium types is that they are absorbed in quantities which exceed the caionic exchange volume as a result of absorption of neutral amines [3].It was established in paper [4] by IR spectroscopy that strong almost symmetrical hydrogen bonds were created between the positively charged NH 3 + groups of cation and the neutral NH 2 groups of the amine. It was proposed that formation 0040-5760/09/4506-0373

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Section: Modelling Of the Section Of The Modified Layer Containing Thmentioning

confidence: 99%

Ab initio calculation of the hydration of organic cations and their associates with amines on the surface of kaolinite

2009

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Statistical-mechanical derivation of generalised langmuir equation and its application for the interpretation of chromatographic data for the adsorption of water and methanol on non-porous carbon materials

et al. 2012

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The chromatographic method is applied to the study of water and methanol adsorption on non porous carbon materials-graphitised carbon black and thermally expanded graphite. It is shown that the processing of the experimental isotherms in coordinates of the classic Langmuir equation results in their lin earization in two ranges of relative pressure, indicating the presence of two types of adsorption centres on the surface, which can be identified as the carboxyl and phenolic hydroxyl groups, respectively. A generalised Langmuir equation based on a statistical mechanical approach is proposed, capable for the description of both monomolecular and polymolecular adsorption on the surface. It is shown that this equation provides for a better description of the adsorption of polar molecules on non porous carbon materials.

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Hydrophobicity of talc basal surface

Tarasevich

Aksenenko

2014

Colloid J

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Gas Chromatographic, Ab Initio and Molecular Statistical Study of the Cluster Adsorption of Water and Methanol Molecules onto Lyophilic Centres on a Generally Lyophobic Adsorbent Surface

Cited by 3 publications

References 12 publications

Ab initio calculation of the hydration of organic cations and their associates with amines on the surface of kaolinite

Ab initio calculation of the hydration of organic cations and their associates with amines on the surface of kaolinite

Statistical-mechanical derivation of generalised langmuir equation and its application for the interpretation of chromatographic data for the adsorption of water and methanol on non-porous carbon materials

Hydrophobicity of talc basal surface

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