Selective liquid adsorption and structural properties of montmorillonite and its hexadecylpyridinium derivatives

Dékány, Imre; Szántó, F.; Nagy, Lajos

doi:10.1007/bf01679173

Cited by 30 publications

(10 citation statements)

References 9 publications

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“…(3) has been investigated by I. Dékány et al in several publications [32]- [36]. It is revealed by the adsorption equilibrium diagrams that when the adsorption of a liquid pair consists of components with significantly different polarities, the value of the equilibrium constant K decreases with increasing surface hydrophobicity of the different silicate surfaces covered by alkyl chains [38]- [43].…”

Section: Adsorption Of Binary Liquid Mixtures On Solid Surfacesmentioning

confidence: 99%

The influence of the interfacial properties of composite catalyst material on the photocatalytic conversion of TiO_2 layer silicates

Kun

Dékány

2009

Per. Pol. Chem. Eng.

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Solid-gas and solid-liquid interfacial properties of titanium dioxide/layer silicate composite sorbents were studied by sorption experiments and the photocatalytic properties were also investigated.The photocatalyst TiO 2 was prepared by the sol-gel method and the sol obtained was used for heterocoagulation of Namontmorillonite at several different mass ratios, yielding supported photocatalysts of various compositions. The TiO 2 content of the samples ranged from 20 to 75 wt%. The specific surface areas of the samples, determined by nitrogen adsorption, ranged from 120 to 290 m 2 /g. The catalytic properties of TiO 2 /montmorillonite composites were tested by photooxidation of dichloro acetic acid (DCA). The specific surface area and the porosity exert a major influence on the photocatalytic efficiency through the interfacial layer properties. The rate of photo-oxidation of DCA depends strongly on the surface accessibility of the intermediates and the specific surface area calculated from gas and liquid mixture adsorption data. The conversion data of DCA presented show that the photocatalytic efficiency of TiO 2 can depend significantly on the accessibility of different molecules to the TiO 2 nanocrystals embedded in the layer silicate support in confined space.

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Section: Adsorption Of Binary Liquid Mixtures On Solid Surfacesmentioning

confidence: 99%

The influence of the interfacial properties of composite catalyst material on the photocatalytic conversion of TiO_2 layer silicates

Kun

Dékány

2009

Per. Pol. Chem. Eng.

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“…Adsorption excess isotherms were determined on hydrophilic and partially hydrophobic layered silicates in methanol-benzene mixtures [62][63][64][65]. From these isotherms the free energy of adsorption ∆ 21 G ϭ f(x 1 ) that is characteristic of surface polarity is derived [60][61][62].…”

Section: Heat Of Immersion On Hydrophilic and Hydrophobic Colloimentioning

confidence: 99%

“…15. In this way the changes in specific surface caused by disaggregation need not be separately monitored, because our data always refer to enthalpy changes accompanying the sorption of molar amounts of the adsorbed material [62,78,79]. The majority of heat evolution is due to preferential adsorption of methanol (see Fig.…”

Section: B Immersional Wetting On Nonswelling Clay Mineralsmentioning

confidence: 99%

“…When the originally hydrophilic surface is modified by long alkyl chains [80][81][82][83][84][85][86][87][88][89][90][91][92], heats of immersion display significantly greater differences. This is well demonstrated by adsorption and X-ray diffraction measurements in toluene (Table 5).…”

Section: Heat Of Wetting On Swelling Clay Mineralsmentioning

confidence: 99%

“…Significant swelling is observed in toluene; therefore, either endothermal-exothermal signals separated in time are registered within the same measurement or the wetting results in only an endothermal heat effect [37,38,62,78,79]. 19-21.…”

Section: Heat Of Wetting On Swelling Clay Mineralsmentioning

confidence: 99%

See 2 more Smart Citations

Microcalorimetric Control of Liquid Sorption on Hydrophilic/Hydrophobic Surfaces in Nonaqueous Dispersions

Garti¹

2000

Surfactant Science

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Interlamellar Liquid Sorption on Hydrophobic Silicates

Dékány¹,

Szántó²,

Weiss

et al. 1985

Ber Bunsenges Phys Chem

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A particular advantage of adsorption measurements on layer silicates is that the adsorption between the silicate layers can be followed by X‐ray measurements. — When the external and internal surface of the silicate montmorillonite is modified by increasing amounts of hexadecylpyridinium cations, the surface character changes from hydrophilicity to hydrophobicity. The changes are evaluated from the excess adsorption isotherms for methanol‐benzene mixtures. The volume Vs of the adsorption phase derived from the isotherms is compared with the free interlayer volume Vf from X‐ray measurements. — On sodium montmorillonite methanol is preferentially adsorbed and the volume increase observed by X‐ray measurements coincides with Vs. If the sodium cations are progressively displaced by hexadecylpyridinium ions the azeotropic point of the type IV isotherms is shifted to lower mole fractions of methanol. The methanol molecules are increasingly displaced from the adsorption phase by benzene molecules. Vf becomes strikingly larger than Vs. — It is concluded that the adsorption layer is not homogeneous in the interlayer space: the methanol molecules are adsorbed on the silicate layers and the benzene molecules are in the vicinity of the hexadecylpyridinium ions. In addition to this adsorption layer the remaining volume is filled with methanol‐benzene mixtures having a composition different from the adsorbed phase and more similar to the bulk phase.

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Selective liquid adsorption and structural properties of montmorillonite and its hexadecylpyridinium derivatives

Cited by 30 publications

References 9 publications

The influence of the interfacial properties of composite catalyst material on the photocatalytic conversion of TiO_2 layer silicates

The influence of the interfacial properties of composite catalyst material on the photocatalytic conversion of TiO_2 layer silicates

Microcalorimetric Control of Liquid Sorption on Hydrophilic/Hydrophobic Surfaces in Nonaqueous Dispersions

Interlamellar Liquid Sorption on Hydrophobic Silicates

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