The sorption of water vapour by active carbon

Dubinin, M. M.; Zaverina, E. D.; Serpinsky, V. V.

doi:10.1039/jr9550001760

Cited by 130 publications

(81 citation statements)

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“…Carrott has argued [8] that the mechanism of methanol adsorption on carbon blacks is similar to that which has been discussed by a number of workers, for example [30][31][32][33] for water in that at low pressures, and surface coverage, hydrogen bonding occurs between methanol and polar surface groups which can be considered as primary adsorption sites. At higher pressures and as surface coverage increases, the methanol adsorbed at primary sites acts as secondary sites.…”

Section: Resultsmentioning

confidence: 96%

Specific and non-specific interactions on non-porous carbon black surfaces

Andreu

Stoeckli

Bradley

2007

Carbon

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The interactions which occur between methanol, ethanol or propanol and the surfaces of non-porous carbon blacks with increasing levels of oxygen chemistry have been studied using adsorption isotherm analysis and immersion calorimetry. Surface oxygen has been controlled by ozone treatment and characterised using X-ray photoelectron spectroscopy, which gives a direct and quantitative measure of surface composition from first-principles, and has not yet been extensively employed in detailed carbon adsorption studies. Nitrogen adsorption at 77 K and heat of immersion Àh i (mJ m À2 ) data for toluene, show that the physical structure of the carbon blacks is not modified by ozone treatment. A systematic shift to higher adsorption values, due to increasing specific hydrogen bonding interactions between the alcohol -OH groups and surface oxygen, is observed in all of the alcohol isotherms as the total oxygen content of the carbon surfaces ([O] T /at.%) increases. This effect is most significant for methanol confirming that the mechanism of adsorption is dominated by hydrogen bonding and therefore dependant on the surface concentration of oxygen sites. It is also observed for ethanol and propanol but is less marked due to the increasing non-specific, dispersion, interactions of the alkyl chain with the non-polar carbon surface. This description is in agreement with the data obtained for the specific enthalpies of immersion Àh i (mJ m À2) into the alcohols and into water or toluene which allow a semi-quantitative assessment off the relative polar and dispersion contributions to the overall interactions as functions of both carbon surface oxygen composition and the molecular structure of the alcohols. An overall correlation is observed between adsorption behaviour, [O] T /at.%, the resulting Àh i values and the characteristic energy E (kJ mol À1 ) of the DRK equation. It is also observed that the values of the affinity coefficient b DRK increase directly as a function of [O] T indicating that this latter parameter may provide a basis for predicting the adsorption isotherms of certain polar vapours on non-porous carbon surfaces. The effects of carbon surface chemistry on the character of adsorption isotherms, which change from Type III for the base N330 (and for a graphitized carbon black N234G) to Type II for the oxidised N330 materials, is discussed and the resulting effects on the surface area parameters S DRK and S BET (m 2 g À1 ) are considered.

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Section: Resultsmentioning

confidence: 96%

Specific and non-specific interactions on non-porous carbon black surfaces

Andreu

Stoeckli

Bradley

2007

Carbon

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“…The adsorption on activated carbon of surface functional groups begins from the low relative pressure P/Po (Kaneko et al, 1989Mowia et al, 2003), where as the predominant adsorption starts near P/Po = 0.5 for activated carbon free of surface functional groups (Ohba et al, in press; Kimura et al). The established mechanism of water adsorption on activated carbon comes from the presence of surface functional groups; water molecules are adsorbed on the surface oxygen sites of carbon pores through hydrogen bonding, forming the clusters of adsorbed molecules (Dubinin et al, 1955;Mowia et al, 2003). However, water vapor can be adsorbed on activated carbon treated at high temperature in a hydrogen atmosphere.…”

Section: Cluster-aided Water Adsorption In Hydrophobic Nanospacesmentioning

confidence: 99%

Nanospace Molecular Science and Adsorption

Kaneko¹,

Ohba²,

Ohkubo³

et al. 2005

Adsorption

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The relationships between the enhanced interaction potential and intensive confinement effect of slit-shaped and cylindrical nanospaces are shown. The structures of water molecules and aqueous ions confined in nanospaces of activated carbon fiber (ACF) and single wall carbon nanohorn (SWNH)s were studied by adsorption, in situ small angle X-ray scattering(SAXS), GCMC simulation, and EXAFS spectroscopy. Water molecules are associated with each other to form the clusters, being stabilized in the carbon nanospaces. This stabilization mechanism of water in carbon nanospaces were evidenced by the interaction potential calculation, GCMC simulation, and the density fluctuation analysis of in situ SAXS. The Ornstein-Zernike analysis of in situ SAXS profiles lead to the conclusion that the critical size of water clusters for predominant water adsorption in hydrophobic carbon nanospaces is about 0.5 nm corresponding to the octomer to decamer. The adsorption hysteresis of water adsorption isotherm of nanoporous carbon was interpreted by the cluster growth, which is confirmed by the density fluctuation analysis. The Rb and Br ions confined in the carbon nanospaces were examined by EXAFS spectroscopy. The remarkable decreases in the hydration number and the water-Rb ion distance of the solution confined in the nanospaces were observed. In particular, the hydration number of the Rb ion in the nanospaces of SWNH is less than 3, being much smaller than the hydration number (6) of the bulk solution. The electrical double layer structure in the nanospaces should be quite different from that in the bulk solution.

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“…It is now believed that the hysteresis observed in water adsorption in microporous carbons is not due to capillary condensation and evaporation, which is typically observed in adsorption of simple gases in mesoporous materials [14]. Adsorption of water in carbon was first put forwarded by Dubinin and co-workers [15], who proposed an entirely different mechanism than the capillary condensation and evaporation of simple gases in mesoporous media, where the Cohan/Kelvin equation applies [3]. Not only hysteresis of water adsorption is observed in porous carbons, but it also occurs with non-porous carbon, even with graphitized thermal carbon blacks (GTCB) [16].…”

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

Scanning curves of water adsorption on graphitized thermal carbon black and ordered mesoporous carbon

Horikawa

Muguruma

et al. 2015

Carbon

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Adsorption isotherms of water on porous carbons generally show large hysteresis loops whose origin is believed to be different from simple gases adsorption in mesoporous solids. In this paper, we discussed in details the behavior of water adsorption isotherms and their descending scanning curves for two carbons of different topologies, a highly graphitized thermal carbon black, Carbopack F, and a highly ordered mesoporous carbon, Hex. For both solids, very large hysteresis loops are observed, but their behaviors are different. For Carbopack F, the loop extends over a very wide range of pressure and the loop is larger when the descending is started from a higher loading; while for Hex, the hysteresis loop shows distinct steps, the number of which depends on the loading where the descending starts. By carefully analyzing the scanning curves from different loadings, we established the mechanism of water adsorption in Hex as a sequence of three steps: (1) water molecules adsorb on functional groups located at the junctions between adjacent basal planes of graphene layers, (2) growth of water clusters around the functional groups, and (3) bridging of adjacent clusters to form larger clusters, followed by a complete filling of mesopores.

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The sorption of water vapour by active carbon

Cited by 130 publications

References 0 publications

Specific and non-specific interactions on non-porous carbon black surfaces

Specific and non-specific interactions on non-porous carbon black surfaces

Nanospace Molecular Science and Adsorption

Scanning curves of water adsorption on graphitized thermal carbon black and ordered mesoporous carbon

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