Virial Analysis of the Adsorption of Trifluorochloromethane and Methane by Microporous Carbons and Zeolites

Adsorption isotherms of trifluorochloromethane (CF 3 Cl) and methane have been determined on a number of microporous carbons and zeolites over a range of temperatures. Analysis of the data by means of the virial equation leads, in most cases, to limiting isosteric heats of adsorption in good agreement with gas chromatographic measurements. A discrepancy found in the case of zeolite 13X is interpreted in terms of specific adsorbate–adsorbent interactions. It is also shown that the shape of the virial plots can provide useful information about the nature of the adsorbent pore structure and the mechanism of pore filling

Gas Chromatographic Study of Specific Physisorption by Activated Carbons

Gas chromatography has been used to study the adsorption of C 2 –C 6 n-alkenes and methanol by activated carbons. Although the higher alkenes adsorb non-specifically only, ethene can also undergo specific interactions with hydroxyl surface sites. The adsorption of alcohols is effected by both adsorbate–adsorbent and adsorbate–adsorbate interactions to such an extent that only in the case of methanol is it possible to obtain reliable chromatographic results. Methanol can undergo specific interactions with both hydroxyl and carbonyl surface sites. The use of methanol and ethene in combination can be used to follow changes in surface polarity brought about by surface modification procedures