Characteristics of Adsorbable Gases and Vapors

Early investigators described adsorption as surface condensation and today it is generally accepted that the forces that bind molecules 

A familiar illustration is the way in which dust particles enable a supersaturated vapor to condense to a liquid another example is found in the dew that forms on a solid surface when the humidity is not sufficienT tovprecipitate as a fog. In acknowledging the greater attractive force of a solid surfaceT v must not lose sight of the fact that adsorption requires the cooperation of the gas molecules, and a greater measure of assistance will be furnished by molecules that more readily condense to a liquid. 

The adsorptions shown in Table 2 2 are not of sufficient magnitude to warrant separation on an industrial scale but as we would anticipate from the condensibility factor, the adsorption of a gas should increase as the temperature is lowered. Dewar,8 in 1904, found that even helium can be adsorbed in large quantities at a sufficiently low temperature. In using temperature as an adjunct for the separation of gases, success can depend on the selection of a temperature appropriate to the separation involved. Yagi9 points out that carbon dioxide is most effectively separated from air between —90° C and — 110°C at higher temperatures carbon dioxide is 

Various ways have been searched to equalize the condensibility factor. One approach is to compare the adsorption of vapors at equal ratios of partial pressure to saturation pressure.14 Pearce et al.15 sought to equalize the influence of condensibility by conducting the adsorption of each vapor at a temperature corresponding to its boiling point. 

From J. N. Pearce and P. E. Peters, in J. Phys. Chem., 42 229 (1938) reprinted by permission of Williams and Wilkins Company, Baltimore, Md. 

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