Characterizing the micropore size distribution of activated carbon using equilibrium data of many adsorbates at various temperatures

In this paper, we present an approach to characterize the micropore size distribution (MPSD) of activated carbon by using multiple-temperature isotherm data of many adsorbates simultaneously. The characteristics of the model are as follows: (1) The MPSD is treated as the intrinsic property of activated carbon (independent of adsorbate) and the sole source of heterogeneity. (2) Different adsorbates have access to different pore size ranges because of their difference in molecular sizes. (3) The adsorbate-adsorbent interaction energy is related to the micropore size through the Lennard-Jones potential theory. This method is examined with the extensive equilibrium data of many adsorbates measured on two different activated carbons under a wide temperature range. The effects of the configuration of the slit-shaped micropores and the local adsorption isotherm are also investigated. It is shown that, with the intrinsic structural parameters, the model proposed can describe very well the adsorption equilibria of different species on each activated carbon and predict reasonably well the multicomponent adsorption equilibria for a number of systems studied in this paper. The physical significance of the results and the applicability of the model are also discussed.