On the use of the dual process Langmuir model for predicting unary and binary isosteric heats of adsorption.

Analytic expressions for unary and binary isosteric heats of adsorption as a function of the adsorbed phase loading were derived from the dual process Langmuir (DPL) model using the Clausius-Clapeyron equation. Unary isosteric heats of adsorption predicted from these expressions for several adsorbate-adsorbent systems were compared to values in the literature predicted from the well-accepted graphical approach using Toth and unilan models (Adsorption Equilibrium Data Handbook; Prentice Hall: NJ, 1989). Predictions from the DPL model were also compared to rare experimental unary and binary isosteric heats of adsorption in the literature for another adsorbate-adsorbent system. In all cases, very good agreement was obtained, showing that the DPL model can be used in adsorption process modeling for accurately predicting not only ideal and nonideal mixed-gas adsorption equilibria (Langmuir 2011, 27, 4700), but also unary and even binary isosteric heats of adsorption.