Affinity coefficients of the Polanyi/Dubinin adsorption isotherm equations

Wood, Gerry O.

doi:10.1016/s0008-6223(00)00128-7

Cited by 188 publications

(119 citation statements)

References 40 publications

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“…As shown earlier [16] for the adsorption of non-specific vapours such as C 6 where E DRK (i) is the characteristic energy derived from the slope of the DRK plot for the vapour (i) and E DRK (C 6 H 6 ) is the energy for the reference vapour which is usually chosen as benzene; is close to, but not necessarily exactly equal to, the value found by Wood for the volume filling of micropores [17]. This means that keeping benzene as the reference requires the actual determination of its isotherm, as well as the isotherms of other vapours (nitrogen, alcohols, etc.).…”

Section: Introduction and Theoreticalmentioning

confidence: 74%

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: Introduction and Theoreticalmentioning

confidence: 74%

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

Andreu

Stoeckli

Bradley

2007

Carbon

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“…Calculation of adsorption energy (Liang, 2008;Ceng et al, 2004;Gao et al, 2001;Dastgheib et al, 2005;Wood, 2001;Wu et al, 2002). An adsorption force field exists on the adsorption surface of AC, and during the adsorption process, it generates an adsorption potential that is determined by the adsorbent, the adsorbate, and the distance between the adsorbate molecule and the adsorbent surface.…”

Section: Physicality Of Acmentioning

confidence: 99%

Effects of activated carbon surface properties on the adsorption of volatile organic compounds

Sun

et al. 2012

Journal of the Air & Waste Management Association

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Physical and chemical properties of activated carbon (AC) were analyzed to investigate the effects of adsorbate properties on AC adsorption performance. Fixed-bed adsorption experiments were conducted with toluene, acetone, and xylene as adsorbates. From the results, the adsorption capacities of the three adsorbates had the following order: xylene > toluene > acetone. The correlation between experimental data and adsorbate properties was also analyzed. The results showed that different functional groups corresponding to the properties of adsorbates influenced the adsorptive properties of AC differently. The adsorption capacity of AC increased linearly as the molecular weight, dynamic diameter, boiling point, and density of the adsorbate increased. However, adsorption capacity decreased as the polarity index and vapor pressure of the adsorbate increased. For adsorption onto three types of AC, the adsorption energies of the three adsorbates had the following order: xylene > toluene > acetone.Implications: This paper focused on the research on adsorption behavior of activated carbon based on adsorbate properties. Adsorption experiments were conducted under the same condition while the adsorbates were toluene, acetone, and xylene, respectively. Correlation analysis between experimental data and adsorbate properties was conducted. The different groups have different influence on the adsorptive properties of ACs. The adsorption capacity of activated carbon increases with the increase of adsorbate molecular weight, dynamic diameter, boiling point, and density, and that this relationship is linear. The relationship between adsorption capacity and the polarity index and vapor pressure of adsorbate shows an opposite trend, and the adsorption capacities and adsorption energies of three kinds of activated carbon for these three adsorbates had the following order: xylene > toluene > acetone.

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“…We have used the correlation proposed by Ye et al [67]: Some of the parameters can be readily obtained; P v , V b can be obtained from thermodynamic properties [68], and V 0 from the carbon manufacturer or by measurement. The affinity coefficient (β) and the pore volume adjusting coefficient (k v ) are parameters that need to be estimated [64,65,67,69] or fitted to adsorption isotherm data. For the most part, we could find literature data for many of the species shown in Appendix 2 and fit equation (5) to those data [50,59,60,67,[69][70][71][72][73][74][75][76][77][78][79][80][81][82][83][84].…”

Section: Adsorption Isothermsmentioning

confidence: 99%

Fuel quality issues in stationary fuel cell systems.

Papadias¹,

Ahmed²

2012

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Affinity coefficients of the Polanyi/Dubinin adsorption isotherm equations

Cited by 188 publications

References 40 publications

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

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

Effects of activated carbon surface properties on the adsorption of volatile organic compounds

Fuel quality issues in stationary fuel cell systems.

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