Adsorption of vapors of argon, nitrogen, n-hexane, and benzene on boron nitride and molybdenum sulfide

Belyakova, L. D.; Киселев, А. В.

doi:10.1007/bf00845935

Cited by 4 publications

(10 citation statements)

References 4 publications

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“…This uptake is steeper for lower temperatures where it occurs at a lower reduced pressure, and the consequent separation in the isotherms in this region is particularly notable in the experimental data. This form of isotherm is in good agreement with the results obtained by Kiselev et al , who measured isotherms of methanol on a highly graphitized thermal carbon black by a gas chromatographic method and noted their unusual form which is not included in IUPAC classification . These isotherms are initially of type III (convex to the pressure axis) and then become concave and change to a type II at higher coverage.…”

Section: Resultssupporting

confidence: 91%

“…However, in many of these publications, the adsorbent is heterogeneous, and the interaction of methanol with the substrate is dominated by defects and functional groups as reflected in the high initial heat of adsorption which then decreases with loading when the adsorption occurs on progressively weaker sites, the characteristic signature of a heterogeneous surface. In a few studies, notably those by Kiselev and co-workers, − adsorption and isosteric heat were measured on highly homogeneous surfaces, but unfortunately their data are limited to a monolayer. The configuration of a crystalline monolayer of adsorbed methanol on graphite has been studied by Morishige over a temperature range 30–215 K, and like Kiselev he was interested mainly in the behavior of a single layer of adsorbed molecules over the graphite surface.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Temperature on Adsorption of Methanol on Graphitized Thermal Carbon Black: A Computer Simulation and Experimental Study

Nguyen

Nicholson

et al. 2011

J. Phys. Chem. C

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We report a computer simulation and experimental study of adsorption of methanol on a highly graphitized thermal carbon black over a range of temperatures to investigate the adsorptive capacity, the isosteric heat, and the configuration of molecules in the adsorbed layer. We include coverage beyond the monolayer region, not previously studied in detail. The adsorption is shown to be strongly affected by hydrogen bonding which results in strong fluid–fluid interaction between the adsorbed molecules. The adsorption isotherms are initially sigmoidal, however, and in the multilayer region the isotherms follow typical type II behavior. The isosteric heat of adsorption of methanol is distinctly different from that of simple gases because of the dominance of the strong interactions between adsorbed molecules over the solid–fluid interactions. The configuration of adsorbed molecules in the submonolayer region favors the formation of 2D cyclic clusters of four or five methanol molecules, which maximizes the hydrogen bonding, while near the end of the completion of the first layer methanol molecules form molecular chains with some degree of 2D-zigzag pattern which again maximizes the hydrogen bonding between all molecules. This is in qualitative agreement with the X-ray diffraction measurements obtained by Morishige (Morishige, K.; Kawamura, K.; Kose, A. J. Chem. Phys. 1990, 93, 5267). When the second and higher layers are formed above the surface, the adsorbate forms clusters in three-dimensional configurations; however, the molecular chains with some degree of 2D-zigzag pattern in the first layer still remain.

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Section: Resultssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Effects of Temperature on Adsorption of Methanol on Graphitized Thermal Carbon Black: A Computer Simulation and Experimental Study

Nguyen

Nicholson

et al. 2011

J. Phys. Chem. C

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“…A linear relationship between the heat of adsorption ∆U and the free energy ∆G (and thus ln K) is usually found for weak interactions such as the physical adsorption that is studied here (38,42). Such a relationship can indeed be found for many vapor adsorption data (1,2,27,38).…”

Section: Resultssupporting

confidence: 52%

“…The heat of adsorption was determined from adsorption coefficients measured at 50, 60, 70, and 80 °C at one constant relative humidity according to the van't Hoff equation () (for this equation see the Appendix). These high temperatures are the most suitable for conducting accurate and quick experiments, and the results may be extrapolated to environmental temperatures as reported earlier (): A linear relationship between the heat of adsorption Δ U and the free energy Δ G (and thus ln K ) is usually found for weak interactions such as the physical adsorption that is studied here ( , ). Such a relationship can indeed be found for many vapor adsorption data ( 1, 2, 27, 38 ).…”

Section: Resultsmentioning

confidence: 81%

Adsorption of VOCs from the Gas Phase to Different Minerals and a Mineral Mixture

Goss

Eisenreich

1996

Environ. Sci. Technol.

135

111

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Vapor adsorption is an important process for the environmental fate of many organic pollutants by influencing the transport and degradation processes in the environment. This work is part of an attempt to understand vapor adsorption by systematically studying the influence of adsorbent, adsorbate, temperature, and relative humidity (RH) on the adsorption equilibrium. Here adsorption to three well-defined minerals (hematite, corundum, and lime) was studied by a chromatographic method. An exponential decrease of the adsorption coefficients of all tested compounds on all adsorbents was found between 30 and 90% RH. Below 30%, the influence of relative humidity was even stronger. The same functional relationship had been found for quartz and clay minerals tested earlier ( , ). We therefore hypothesize that this relationship may be valid for all minerals in general. Differences in the surface area-normalized adsorption on different mineral surfaces were found, and they were most distinct at low relative humidities. These differences became smaller with increasing relative humidity and disappeared when humidity approached 100% RH. The extrapolated adsorption coefficients at 100% RH agree with those reported for a bulk water surface. At close to 100% RH, the adsorbed water film apparently was thick enough to prevent influence of the mineral surface on adsorption. The heats of adsorption did show a slight dependence on the mineral surface. As expected, they increased for adsorbents and compounds with increasing adsorption coefficients. Finally, the adsorption of organic vapors to a mixture of two minerals, Ca-kaolinite and corundum, was found to equal the linear sum of the contributions of the single minerals.

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“…The term highly graphitized refers to a carbon black which has been graphitized at 2700 K, or greater, under vacuum or in a reducing environment of pure hydrogen. Three studies of water adsorption on such a carbon black were those completed by Belyakova et al, Easton and Machin, and Tarasevich et al The one of greater interest to this study is that of Belyakova et al since it gives relatively detailed isotherms in the region of submonolayer coverage an ambient temperature. The carbon black used in their study was one of the most uniform carbon blacks ever reported.…”

Section: Resultsmentioning

confidence: 98%

Simulation Study of Water Adsorption on Carbon Black: The Effect of Graphite Water Interaction Strength

Birkett

2007

J. Phys. Chem. C

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The adsorption of water on carbon black has been calculated on several model graphitized carbon blacks using Monte Carlo simulation. The surface is modeled using different interaction strengths for a Steele type potential and the placement of various functional groups on the surface. The results for the various surface configurations are compared with the few experimental results available in the literature. Traditionally used parameters for the Steele potential provide isotherms with no similarity to those seen in experiment. Increased interaction well depths with the surface lead to more realistic isotherms but still require strongly attractive functional groups for qualitative agreement. The well depth used to achieve this falls within the realm of interaction strengths proposed in the literature by various methods. Full agreement with experiment isotherms is not achieved apparently because of a lack of large clusters formed in the simulations.

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Adsorption of vapors of argon, nitrogen, n-hexane, and benzene on boron nitride and molybdenum sulfide

Cited by 4 publications

References 4 publications

Effects of Temperature on Adsorption of Methanol on Graphitized Thermal Carbon Black: A Computer Simulation and Experimental Study

Effects of Temperature on Adsorption of Methanol on Graphitized Thermal Carbon Black: A Computer Simulation and Experimental Study

Adsorption of VOCs from the Gas Phase to Different Minerals and a Mineral Mixture

Simulation Study of Water Adsorption on Carbon Black: The Effect of Graphite Water Interaction Strength

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