Nouveaux aspects de l’interprétation des isothermes d’absorption de mélanges liquides binaires sur des surfaces solides

Schay, Géza; Nagy, Lajos

doi:10.1051/jcp/1961580149

Cited by 60 publications

(29 citation statements)

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“…For binary mixtures, a negative excess of one component means a positive excess of the other. By considering the region of adsorption isotherms in which the excess decreases almost linearly with increasing volume fraction of acetonitrile in the mobile phase,9, 43, 52 one arrives through Equation (2) at the conclusion that the maximum amounts of acetonitrile that can be adsorbed by the bonded phases are roughly 9 and 13 μmol m −2 for PFP cap ‐SP and PFH cap ‐SP, respectively. In the inset of Figure 5, the organic‐rich mobile‐phase region of the adsorption isotherm is magnified.…”

Section: Resultsmentioning

confidence: 99%

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Revealing the Fine Details of Functionalized Silica Surfaces by Solid‐State NMR and Adsorption Isotherm Measurements: The Case of Fluorinated Stationary Phases for Liquid Chromatography

Ciogli

Simone

Villani

et al. 2014

Chemistry A European J

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The structural and chromatographic characterization of two novel fluorinated mesoporous materials prepared by covalent reaction of 3-(pentafluorophenyl)propyldimethylchlorosilane and perfluorohexylethyltrichlorosilane with 2.5 μm fully porous silica particles is reported. The adsorbents were characterized by solid state (29)Si, (13)C, and (19)F NMR spectroscopy, low-temperature nitrogen adsorption, elemental analysis (C and F), and various chromatographic measurements, including the determination of adsorption isotherms. The structure and abundance of the different organic surface species, as well as the different silanol types, were determined. In particular, the degree of so-called horizontal polymerization, that is, Si-O-Si bridging parallel to the silica surface due to the reaction, under "quasi-dry" conditions, of trifunctional silanizing agents with the silica surface was quantified. Significant agreement was found between the information provided by solid-state NMR, elemental analysis, and excess isotherms regarding the amount of surface residual silanol groups, on the one hand, and the degree of surface functionalization, on the other. Finally, the kinetic performance of the fluorinated materials as separation media for applications in near-ultrahigh-performance liquid chromatography was evaluated. At reduced velocities of about 5.5 (ca. 600 bar backpressure at room temperature) with 3 mm diameter columns and toluene as test compound, reduced plate heights on the order of 2 were obtained on columns of both adsorbents.

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Section: Resultsmentioning

confidence: 99%

“…Excess adsorption isotherms can be employed to estimate the capacity and thickness of a surface phase (absolute adsorption) 32. 39, 43 The volume of i in the stationary phase ${V_i^{\rm{S}} }$ and the stationary‐phase volume V S can be assessed by the linear region of the excess isotherm [Eq. (2)].…”

Section: Methodsmentioning

confidence: 99%

Revealing the Fine Details of Functionalized Silica Surfaces by Solid‐State NMR and Adsorption Isotherm Measurements: The Case of Fluorinated Stationary Phases for Liquid Chromatography

Ciogli

Simone

Villani

et al. 2014

Chemistry A European J

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“…Microscopic pictures provide visual information on the structure of the probes. Though the resolution of the scanning tunnel microscopic pictures is rougher in the case of amorphous carbon samples than in the case of the samples showing ordered graphite structure, the resolution limit is correct compared with the roughness of the carbon matrix. − The chemical (polar−nonpolar) character of the carbon surface can be tested by using an adequate binary liquid mixture. − The heterogeneity of the activated carbons prepared from the previously mentioned precursors proved to be independent of their origin according to the liquid adsorption data.…”

Section: Introductionmentioning

confidence: 99%

Comparative Study of Active Carbons from Different Precursors

Bóta¹,

László²,

Nagy³

et al. 1997

Langmuir

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The effect of the precursor on the morphology, the structure, and the adsorption properties of the activated carbon in the case of poly(ethylene terephthalate) and cellulose, was studied. Scanning tunnel microscopy, X-ray scattering methods, and adsorption from gas and liquid phases were applied to answer the problem. According to adsorption data, the micropore structure and the chemical character of the two activated samples were found to be practically independent of their origin, but essential structural dissimilarities were concluded from SAXS data. STM illustrated the effect of the precursor's structure only in dimensions which are considerably larger than the size of the regions governing the microporous behavior. The morphological differences in the carbon correspond to the different links between the crystallites. Presumably these connections strongly affect the diffusion of the activating agent and thus the pore structure developing during the activation process.

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“…The areal reduced excess adsorption isotherms for methanol (1) + benzene (2) and 2-propanol (1) + n -heptane (2) systems on silica gel Si-40 and Si-100 are presented in Figures and . As seen there, the shape of experimental isotherms is type II according to Schay−Nagy classification …”

Section: Resultsmentioning

confidence: 98%

Adsorption from the Liquid Phase on Silica Gels of Various Structural Heterogeneity

1999

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Competition of liquid components for silica gel surface was tested for binary liquid mixtures: methanol + benzene and 2-propanol + n-heptane. The adsorption isotherms were measured using silica gels for column chromatography Si-40 and Si-100 from Merck. On the basis of specific surface excess isotherms the surface layer capacities were calculated. Taking into account the properties of the bulk solutions, the influence of geometrical structure of silicas on the composition of the surface phase is discussed.

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Nouveaux aspects de l’interprétation des isothermes d’absorption de mélanges liquides binaires sur des surfaces solides

Cited by 60 publications

References 0 publications

Revealing the Fine Details of Functionalized Silica Surfaces by Solid‐State NMR and Adsorption Isotherm Measurements: The Case of Fluorinated Stationary Phases for Liquid Chromatography

Revealing the Fine Details of Functionalized Silica Surfaces by Solid‐State NMR and Adsorption Isotherm Measurements: The Case of Fluorinated Stationary Phases for Liquid Chromatography

Comparative Study of Active Carbons from Different Precursors

Adsorption from the Liquid Phase on Silica Gels of Various Structural Heterogeneity

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