A molecular thermodynamics approach is developed in order to describe the adsorption of fluids on solid surfaces. The new theory is based on the statistical associating fluid theory for potentials of variable range [A. Gil-Villegas et al., J. Chem. Phys. 106, 4168 (1997)] and uses a quasi-two-dimensional approximation to describe the properties of adsorbed fluids. The theory is tested against Gibbs ensemble Monte Carlo simulations and excellent agreement with the theoretical predictions is achieved. Additionally the authors use the new approach to describe the adsorption isotherms for nitrogen and methane on dry activated carbon.

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A molecular-based approach for modelling mixtures adsorbed onto solid surfaces using the Statistical Associating Fluid Theory for Potentials of Variable Range (SAFT-VR) for three-and two-dimensional systems is presented in this work. The theory is used to describe the adsorption of binary mixtures of carbon dioxide, methane and nitrogen onto dry activated carbon, describing the overall adsorption phase diagram reported for these systems even at high pressures.

Résumé -Thermodynamique moléculaire de l'adsorption à l'aide de systèmes à potentiels discrets -Un modèle thermodynamique de fluide basé sur des potentiels discrets a été développé pour décrire l'adsorption sur une surface solide. À l'aide de théories de la perturbation, comme la théorie SAFT (Statistical Associating Fluid Theory), et la théorie DPT (Discrete Potential Theory), en combinaison avec la simulation moléculaire, nous avons formulé une approche bi-dimensionnelle qui permet de décrire des systèmes qui intéressent l'industrie pétrolière, tels les isothermes d'adsorption du CO 2 ou des asphaltènes. Abstract -Molecular Thermodynamics of Adsorption using Discrete-Potential Systems

A simple molecular thermodynamic approach is applied to the study of the adsorption of gases of chain molecules on solid surfaces. We use a model based on the Statistical Associating Fluid Theory for Variable Range (SAFT-VR) potentials [A. , J. Chem. Phys. 106 (1997) 4168] that we extend by including a quasi-two-dimensional approximation to describe the adsorption properties of this type of real gases [A. Martínez, M. Castro, C. McCabe, A. Gil-Villegas, J. Chem. Phys. 126 (2007) 074707]. The model is applied to ethane, ethylene, propane, and carbon dioxide adsorbed on activated carbon and silica gel, which are porous media of significant industrial interest. We show that the adsorption isotherms obtained by means of the present SAFT-VR modeling are in fair agreement with the experimental results provided in the literature.