ESTIMATION OF THE ADSORBENT CAPACITIES FROM THE ADSORPTION-ISOTHERM OF BINARY-LIQUID MIXTURES ON SOLIDS

Methods available in the literature to estimate the adsorbent capacity from the adsorption isotherm of binary liquid mixtures generally assume that the adsorptives are identical, that the adsorbed phase is monolayer, and that the separation factor (or selectivity) of the system is constant. These assumptions limit the application and reliability of these methods. Based on the concept of the average molecular thickness of the adsorbed-phase layer, an alternative method is proposed that addresses the shortcomings of the existing methods. The substitution ratio, r12, which represents the molecular size differences in the adsorptives, is calculated within +/- 5% of the experimental values, for the systems tested. The characteristics of the adsorbent selectivities are successfully modeled after some hyperbolic functions. Compared with the experimental results, the proposed method gives a reliable estimate of the adsorbent capacities.