Density Functional Theoyr Study On Interfacial Property Of Binary Mixture

The interfacial tension of solutions has a considerable influence on thetransfer of mass and energy across interfaces. It is a basic thermodynamicproperty that plays an important role in some engineering applicationsincluding the adhesion of thin films over surfaces, the stability of foams, thegeneration of bubbles and drops. As a result, a detailed understanding ofinterfacial tension is essential from a practical perspective. In recent years,great efforts have been made in developing a reliable theoretical platform forthe interfacial properties of fluid mixtures. However, it is still a challengebecause of their unsymmetrical nature.In this work a density functional model is constructed to describe theinterfacial properties of fluid mixtures. In the theoretical model, the modifiedfundamental measure theory (MFMT) is employed to describe hard spherecontribution and the first-order mean spherical approximation (FMSA) andassociating fluid theory are incorporated to describe the attractive contribution. The thesis focus on the different binary mixtures: nonpolar-nonpolar fluidmixtures: Ar(1)+Kr(2),CO₂(1)+heptanes (2) and methane(1)+pentane(2);nonpolar-associating fluid mixtures: CO₂(1)+ethanol (2), CO₂(1)+water (2)and hexane(1)+2-butanol(2); nonpolar-polar fluid mixture:CO₂(1)+acetone(2).Partial results are tested by the available experimental data, showing the goodpredictive capability of the theory to the interfacial property of binarymixtures.The above theoretical approach is then extended to vapor–liquid–solidternary system. The interfacial properties of N₂(1)+water (2) system in thepresence of a hydrophobic wall are described. The density profiles of thedissolved N2and the water in the vicinity of the hydrophobic wall arecalculated, in which gas enrichment and liquid depletion are easily to find.Based on the supersaturation induced by the gas enrichment and liquiddepletion, the free energy barriers with different supersaturation ratio ordifferent hydrophobicity for bubble nucleation are approximately estimated toanalyze the possibility of spontaneous bubble nucleation.