Using local IAST with micropore size distribution to predict multicomponent adsorption equilibrium of gases in activated carbon

A mathematical model is proposed to predict multicomponent adsorption equil ibrium of gases in a heterogeneous activated carbon. The model, called MPSD -IAST, assumes a micropore size distribution (MPSD) to represent the energe tic heterogeneity of adsorbent and uses the ideal adsorbed solution theory (IAST) to describe the local multicomponent adsorption equilibrium within a given pore. The overall adsorption isotherm is the integral of the local a dsorbed-phase concentration over the complete pore size distribution range accessible to the adsorbate molecule. The adsorbate-adsorbent interaction e nergy is related to micropore size via the Lennard-Jones potential theory, and the size exclusion effect is taken into account in the competitive adso rption of different species for a given pore. The MPSD-IAST model predictio ns are examined with the equilibrium data of mixed gases measured on two co mmercial activated carbons (Ajax and Norit). The results are compared with those obtained using a MPSD-EL model where the local adsorption isotherm is described by an extended Langmuir equation.