Titel
"Adsorption of Inhomogeneous Fluids with Classical Density Functional Theory and PC-SAFT EoS"
Abstract
Classical Density Functional Theory (DFT) is consistent framework used to study the phase behaviour and surface properties of inhomogeneous fluids. It is based in the famous Density Functional Theory developed by Walter Kohn and Pierre Hohenberg that is used for the determination of the electronic properties of materials from the electronic density (‘distribution of electrons’), work that later made them won the Nobel Prize in chemistry. In contrast, classical DFT determines the thermodynamic properties of fluids from the distribution of particles, or particle density.
Inhomogeneous fluids are found in thermodynamic systems where the particle density shows oscillations due to the presence of surfaces, e.g. fluid-fluid and fluid-solid interfaces. In this kind of systems, the final distribution of particles leads to phenomena related to adsorption, surface tension, wetting transition, capillarity, among others. Therefore, classical DFT has shown to be a powerful tool to study surface phenomena.
The implementation of a classical DFT framework consists on the definition of a Helmholtz free energy functional that takes into account the interactions between the particles, e.g. repulsion, chain formation, dispersive attraction, association, polar and electrostatic interactions. In this way, it is possible to use as reference an equation of state for bulk fluids such as the Perturbed Chain Statistical Association Fluid Theory [3] (PC-SAFT) together with classical DFT for the calculation of adsorption for inhomogeneous systems. Furthermore, with this implementation it is possible to use the original pure component parameters for bulk fluids of the equation of states directly into the classical DFT calculations.