Adsorption of vapors on nonporous sorbent models with a physically modified surface

Sarakhov, A. I.; Dubinin, M. M.; Berezkina, Yu. F.; Zaverina, E. D.

doi:10.1007/bf00909155

Cited by 9 publications

(5 citation statements)

References 5 publications

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“…Adsorption of gases on homogeneous graphene layers has been extensively studied because of the fundamental interest in developing adsorption theory and investigating the intrinsic interaction between different fluids and the basal plane of graphite. − Graphitized thermal carbon black (GTCB) is a good experimental subject to represent graphene layers, because it is synthesized by thermal decomposition of a carbonaceous precursor and graphitized at very high temperatures (at least 2700 °C) to produce highly homogeneous basal planes. However, experimental observations suggest that this material may nevertheless possess strong sites and that the interaction of adsorbate with the substrate is dominated by these sites , at very low loadings.…”

Section: Introductionmentioning

confidence: 99%

Existence of Ultrafine Crevices and Functional Groups along the Edge Surfaces of Graphitized Thermal Carbon Black

Zeng

Nicholson

2015

Langmuir

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Adsorption of different gases on graphitized thermal carbon black (GTCB) has been studied with a new molecular model to examine the consequences of micropore crevices and functional groups at the junctions between adjacent basal planes. Adsorption was simulated in the Grand Canonical Monte Carlo ensemble and the theoretical Henry constants were calculated by Monte Carlo volume integration over the Boltzmann factor of the solid-fluid potential. The simulation results are in good agreement with high-resolution experimental isotherms for argon on mineralogical graphite measured by Lopez-Gonzalez et al.1 From detailed inspection of the argon isotherms at extremely low coverages, we find two distinct Henry law regions, separated by a plateau (suggesting saturation of the stronger sites) that spans over a few decades of pressure. The first Henry law region is attributed to adsorption in the ultrafine crevices at the junctions between two adjacent basal planes, and the second region corresponds to adsorption on the basal plane, as confirmed by the theoretical Henry constant. The simulated isosteric heat and snapshots of molecular configurations show that argon adsorbs preferentially in the ultrafine crevices where there is a deep potential well due to overlap from the opposite pore walls. Similar behavior was found for other nonassociating fluids (Ar, N2, and CO2); however, for associating fluids (NH3 and H2O), the strong sites for adsorption and nucleation come from the combined effects of functional groups and ultrafine crevices, since the latter cannot alone account for the observed adsorption.

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Section: Introductionmentioning

confidence: 99%

Existence of Ultrafine Crevices and Functional Groups along the Edge Surfaces of Graphitized Thermal Carbon Black

Zeng

Nicholson

2015

Langmuir

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“…Many other experimental adsorption studies of simple gas adsorption on GTCB have been reported, amongst which may be mentioned those of Isirikyan and Kiselev (1962);Sarakhov et al (1961Sarakhov et al ( , 1963; Berezkina et al (1969); Kruk et al (1999);and Gardner et al (2000) who have also reproduced experimental results by simulation and density functional calculations.…”

Section: Argon and Nitrogen On Graphitementioning

confidence: 98%

The interplay between molecular layering and clustering in adsorption of gases on graphitized thermal carbon black – Spill-over phenomenon and the important role of strong sites

Tan

Zeng

et al. 2015

Journal of Colloid and Interface Science

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We analyse in detail our experimental data, our simulation results and data from the literature, for the adsorption of argon, nitrogen, carbon dioxide, methanol, ammonia and water on graphitized carbon black (GTCB), and show that there are two mechanisms of adsorption at play, and that their interplay governs how different gases adsorb on the surface by either: (1) molecular layering on the basal plane or (2) clustering around very strong sites on the adsorbate whose affinity is much greater than that of the basal plane or the functional groups. Depending on the concentration of the very strong sites or the functional groups, the temperature and the relative strength of the three interactions, (a) fluid-strong sites (fine crevices and functional group) (F-SS), (b) fluid-basal plane (FB) and (c) fluid-fluid (FF), the uptake of adsorbate tends to be dominated by one mechanism. However, there are conditions (temperature and adsorbate) where two mechanisms can both govern the uptake. For simple gases, like argon, nitrogen and carbon dioxide, adsorption proceeds by molecular layering on the basal plane of graphene, but for water which represents an extreme case of a polar molecule, clustering around the strong sites or the functional groups at the edges of the graphene layers is the major mechanism of adsorption and there is little or no adsorption on the basal planes because the F-SS and FF interactions are far stronger than the FB interaction. For adsorptives with lower polarity, exemplified by methanol or ammonia, the adsorption mechanism switches from clustering to layering in the order: ammonia, methanol; and we suggest that the bridging between these two mechanisms is a molecular spill-over phenomenon, which has not been previously proposed in the literature in the context of physical adsorption.

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“…Figure 3 demonstrates the appearance and growth of two water proton NMR lines. Initially only line B appeared, which obviously demonstrates that the adsorption process begins in micropores, which serve as primary adsorption centers and accumulate water molecules (15,(20)(21)(22). Line A does not appear until the integral intensity of line B reaches the saturation value equal to that for suspension.…”

Section: General Considerationsmentioning

confidence: 99%

Peculiarities in the Water Adsorption and Morphology of Carbon Chars Assessed by NMR

Odintsov

Temnikov

Belford

et al. 2001

Journal of Colloid and Interface Science

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Adsorption of vapors on nonporous sorbent models with a physically modified surface

Cited by 9 publications

References 5 publications

Existence of Ultrafine Crevices and Functional Groups along the Edge Surfaces of Graphitized Thermal Carbon Black

Existence of Ultrafine Crevices and Functional Groups along the Edge Surfaces of Graphitized Thermal Carbon Black

The interplay between molecular layering and clustering in adsorption of gases on graphitized thermal carbon black – Spill-over phenomenon and the important role of strong sites

Peculiarities in the Water Adsorption and Morphology of Carbon Chars Assessed by NMR

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