Vapor−Liquid Equilibria and Interfacial Tensions of Associating Fluids within a Density Functional Theory

Abstract

A self-consistent density functional theory is applied to investigating the phase behavior and interfacial tensions of water and low-molecular-weight normal alkanols. For the bulk phases, the density functional theory is reduced to an equation of state that provides an accurate description of saturation pressures as well as vapor−liquid phase diagrams. Near the critical region, the long-range fluctuations are taken into account using a renormalization group theory. With the same set of molecular parameters, the theory yields satisfactory results for both bulk properties and surface tensions of the associating fluids investigated at all temperatures.

A density functional theory for vapor-liquid interfaces using the PCP-SAFT equation of state

“…No parameter is adjusted to interfacial properties for these systems and the agreement with the experimental data is very good. Similar to the study of Fu and Wu, 24 tational distribution of dipoles across the interface is not resolved in our approach. A fluid of dipoles actually lowers its grand potential ⍀͑V , T , ͒ by a nonisotropic orientational distribution in inhomogeneous systems.…”

“…18 The TPT1 of Wertheim is formulated in density functional form and has been applied to inhomogeneous associating fluids in several studies. [19][20][21][22][23][24][25] In the molecular model of SAFT-type equations of state, one represents molecules as connected spherical segments, resembling the molecular configuration of real molecules in a coarse-grained way. The connection of segments to form segment chains is achieved by considering a mixture of initially free spheres ͑with association sites͒ in the limit of complete association.…”

Capillary condensation in pores with rough walls: A density functional approach

“…The theory combines the approach of Schmidt [32] with the theory of Yu and Wu [43] and Cao and Wu [44]. The latter theory can be successfully applied to describe adsorption of such important from experimental point of view [45][46][47][48][49] complex fluids as carbon dioxide, hydrocarbons, polymers and many others [50]. Moreover, this theory is numerically almost as simple as density functional theories of simple fluids [26].…”

Investigation of Surface Tensions for Pure Fluids outside and inside the Critical Region

“…Investigations [28][29][30][31][32][33] show that the MFMT preserves all the advantages of the original FMT by Rosenfeld 34 but gives improved structural and thermodynamic properties of hard-sphere fluids in the bulk and at inhomogeneous conditions as well. The work of Fu and Wu 3,35 shows that MFMT always yields better results for interfacial properties of model Yukawa fluids than LDA as it correctly takes into account both the scalar and vector contributions.…”