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

Preliminary studies of adsorption kinetics on activated carbon provided some tentative evidence for a possible compensation effect where the activation energies and In(preexponential factors) obtained from the Arrhenius equation 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 combination with our previous results for water, n-octane, and n-nonane adsorption 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 of 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 desorption on microporous carbons and may extend further to other porous systems.