Adsorption-Journal of the International Adsorption Society
Experimental and simulated data for adsorption of gas mixtures on energetically heterogeneous surfaces like activated carbon and zeolites exhibit negative deviations from ideality. The deviations are large in some cases, with activity coefficients at infinite dilution equal to 0.1 or less. Similar molecules form ideal mixtures, but molecules of different size or polarity are nonideal. Equations for bulk liquid mixtures (Wilson, Margules, etc.) do not apply to isobars for adsorbed mixtures. A two-constant equation for activity coefficients as a function of composition and spreading pressure is in good agreement with theory, simulation, and experiment.
Talu, Orhan; Li, Jianmin; and Myers, Alan L., "Activity Coefficients of Adsorbed Mixtures" (1995). Chemical & Biomedical Engineering Faculty Publications. 82.
Talu, O., Li, J., , & Myers, A. L. (1995). Activity coefficients of adsorbed mixtures. Adsorption, 1(2), 103 - 112. doi:10.1007/BF00704999
The final publication is available at Springer via http://dx.doi.org/10.1007/BF00704999