Adsorption of Chain Molecules in Slit-Shaped Pores: Development of a SAFT-FMT-DFT Approach

Density functional theory (DFT) is commonly used to treat the adsorption of molecules in carbon and silica pores of various geometries. In this work, we develop a DFT with an accurate molecular-based equation of state to calculate thermodynamic properties using fundamental measure theory (FMT), which is a rigorous approach for the treatment of homogeneous and nonhomogeneous hard-sphere fluids. A theoretical framework results with adsorbing molecules treated as hard-sphere chains with square-well attractive interactions. The Mansoori–Carnahan–Starling–Leland and Carnahan–Starling–Boublik equations of state are used for the hard-sphere interactions, and a version of the statistical associating fluid theory for potentials of variable range (SAFT-VR) is used to describe the square-well fluid. First- and second-order perturbative attractive terms are included in the theory. Theoretical predictions are in good agreement with published results for Monte Carlo simulations of the adsorption of chain molecules. In ...