Heterogeneity in solution adsorption: Edge carbon and oxide coverages

Coltharp, Marcellus T; Hackerman, Norman

doi:10.1016/0021-9797(73)90362-7

Cited by 33 publications

(4 citation statements)

References 15 publications

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“…They contain both nonpolar, i.e., benzophilic, and polar regions. The latter increases with the number of carbon atoms being at the edge of the crystallites . As the x 1,a values, i.e., the ratio of the polar/nonpolar regions are very similar in the two samples, we presume that the ratios of the outer polar and inner nonpolar regions of the crystallites and thus their lateral extensions are almost identical in the two samples.…”

Section: Resultsmentioning

confidence: 70%

“…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%

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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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Section: Resultsmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Comparative Study of Active Carbons from Different Precursors

Bóta¹,

László²,

Nagy³

et al. 1997

Langmuir

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“…It would be helpful to have a quantitative means of classifying or ranking isotherms according to sign and extent of deviation from the IAS. A simple numerical ranking would aid the often difficult comparisons between members of a set of theoretical or experimental isotherms . Further, such classifying would provide useful background information for determination of distributions of surface energy when desired or calculation of adsorbed phase activity coefficients when appropriate.…”

Section: Introductionmentioning

confidence: 99%

On Numerical Classification of Solution Adsorption Isotherms

Coltharp

2005

Langmuir

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To numerically classify solution adsorption isotherms, a difference or deviation measure, DS(mc) (the relative difference between two sums of the adsorption maximum's characteristics of selectivity isotherms x 100), is derived. The measure is applicable to completely miscible binary solutions on solids. This quantity evaluates the difference between an adsorption system and the ideal adsorption system (ideal adsorbed and bulk phases, homogeneous surface, and equal molar area solution components) at the point of maximum adsorption. For model systems, DS(mc)s are calculated at several levels of surface heterogeneity (Gaussian distribution of surface energy) and for different signs of phase nonideality (regular solution phases) on a homogeneous surface and on a simple two-site-type heterogeneous surface. All heterogeneous surfaces have negative DS(mc) values, but nonideal phases have DS(mc)s with signs opposite to the sign of deviation from Raoult's law. DS(mc)s from both U- and S-shape isotherms are reported for 16 experimental systems consisting of hydrocarbon mixtures and both alcohol + hydrocarbon and alcohol + water solutions or acetone + carbon tetrachloride on several silica gels and a variety of carbons.

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“…, 1978bJaroniec, 1977;Bulow et al 1982). It has been shown that in the case of certain solids, such as silica gels or active carbons, the energetic heterogeneity of a gas/solid or solid/solution interface is of prime importance in governing the behaviour of adsorption isotherms, (Jaroniec, 1977;Jaroniec et al 1978a;Coltharp and Hackerman, 1973) heats of adsorption (Rudzinski et al 1983), heat capacities (Rudzinski and Jagiello, 1982), etc. In a great number of cases surface heterogeneity appears to be among the most important physical factors influencing the behaviour of adsorption systems.…”

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confidence: 99%

Adsorption from multicomponent gas mixtures on the heterogeneous surfaces of solid catalysts

Wojuciechowski

Hsu

Rudziński³

1985

Can J Chem Eng

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A generalized isotherm for adsorption of gas mixtures with different molecular sizes on heterogeneous surfaces has been derived. The isotherm retains the form of the equation derived by Crickmore and Wojciechowski (C-W). The single heterogeneity factor in the C-W equation is replaced by a product C , a , which accounts for the combined effect of surface heterogeneity and molecular size. The term is non-separable by experiment but the concept is very important in considering catalytic reactions where a great variety of molecular sizes and types can be adsorbed on the catalyst surface.

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Heterogeneity in solution adsorption: Edge carbon and oxide coverages

Cited by 33 publications

References 15 publications

Comparative Study of Active Carbons from Different Precursors

Comparative Study of Active Carbons from Different Precursors

On Numerical Classification of Solution Adsorption Isotherms

Adsorption from multicomponent gas mixtures on the heterogeneous surfaces of solid catalysts

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