Compensation effect for the kinetics of adsorption/desorption of gases/vapors on microporous carbon materials

Preliminary studies of adsorption kinetics on activated carbon provided som e tentative evidence for a possible compensation effect where the activatio n energies and In(preexponential factors) obtained from the Arrhenius equat ion obey a linear correlation. However, a detailed analysis was not carried out. The adsorption characteristics of a series of n-alcohol vapors on the activated carbon BAX950 were investigated over the relative pressure range p/p(o) = 0-0.97, for temperatures in the range 288-318 K. These data, in c ombination with our previous results for water, n-octane, and n-nonane adso rption provide a comprehensive adsorption kinetic study on an active carbon covering a full range of adsorptives with varying hydrophilic/hydrophobic character to establish the general validity, applicability, and mechanism o f the compensation effect. The results are discussed with reference to the pore structure and the adsorption mechanism. Detailed comparisons show that the compensation effect is a general phenomenon for adsorption and desorpt ion on microporous carbons and may extend further to other porous systems.