This research proposes a modified two-dimensional Peng-Robinson equation model to predict adsorption
isotherm in adsorbate-adsorbent systems. The parameters of the proposed model are calculated by using the optimization
of experimental data for the different single gas adsorption systems at various temperatures. The experimental
adsorption equilibrium data of adsorbate-adsorbent systems was compared with the calculated results in our
proposed model and the two-dimensional Hill-deBoer equation model. The proposed model as indicated in the results
shows a better prediction of the experimental results compared with two others.