Calculation of vapor-liquid interfacial surface thickness of associating fluid using density profile and SAFT-DFT approach

Interfacial behaviour plays an important role in broad area of applied science and engineering. A knowledge of surface tension, interfacial profiles and interfacial thickness are keys to understanding of surface and interfacial process and design of processes such as separation, catalyst reactions and adsorption phenomena. The thermodynamic description of the vapor–liquid interface goes back to Gibbs, who defined it as a physical boundary between two distinct phases. van der Waals showed that there is a density gradient between liquid and vapor phases, but accurate prediction of interfacial properties of complex fluid such as water, alcohols and chain molecules have been possible with using modern Equation Of State(EOS) that are based on perturbation theory. One of the most successful modern EOS for complex fluids is the Statistical Associating Fluid Theory (SAFT). Using SAFT EOS with Density Functional Theory (DFT), the accurate surface properties of an inhomogeneous fluid can be predicted. In this work we used a new method, called Cross Intersection Method (CIM), and SAFT-DFT approach for calculating interfacial thickness of associating fluids.