Macroscopic adsorption phenomena such as pore condensation and hysteresis effects originate from microscopic fluid-solid interactions. Recent progress is based on further development of molecular methods like classical density functional theory (DFT). DFT is a powerful computational tool and gives access to the inhomogeneous fluid structure in nano- and mesoporous media. The description of the fluid-fluid interactions by the PC-SAFT equation of state enables the prediction of adsorption isotherms of pure substances and mixtures over a wide pressure range.
The porous medium is often decribed by an external field which is only varying in the spacial coordinate perpendicular to the wall. This results in structureless and chemically homogeneous walls. The proposed solid model takes the atomistic nature of the solid into account and decomposes the solid into interaction sites which are placed on a lattice grid.
This study shows the influence of microscopic roughness and chemical heterogeneity on the adsorption behaviour of n-alkanes. The solid model is then extended to real ordered porous media like zeolites and covalent organic frameworks.