Non-classical interfacial tension and fluid phase behaviour

Classical density functional theory for the prediction of the surface tension and interfacial properties of fluids mixtures of chain molecules based on the statistical associating fluid theory for potentials of variable range

“…(29). The perturbation theory of A [{ρ m (r)}] of molecules of type i not bonded at a given site A at a point r in the fluid can be expressed as a set of mass-action equations:…”

“…At about the same time, Poser and Sanchez 27 combined a lattice theory with DGT to describe the interfacial tension of hydrocarbon mixtures and polymeric systems. Peters and collaborators have made extensive use of the density gradient approach with the PR EOS or with the Associating-Perturbed-Anisotropic-Chain Theory (APACT) to study binary and ternary mixtures of carbon dioxide + butane + decane 28,29 , water + benzene 30,31 , water + ethanol + hexane 31,32 , and gas condensates of n-alkane mixtures 33 . Similar studies with cubic EOSs have been made to describe the interfacial tension of a wide variety of mixtures including: light gases (carbon dioxide, nitrogen or methane) and hydrocarbons [34][35][36] ; refrigerants, nitrogen, argon, alkanes and carbon dioxide 37 ; and associating and non-associating mixtures 38,39 .…”

Direct calculation of interfacial properties of fluids close to the critical region by a molecular-based equation of state

“…They obtained good agreement in general, but the scaling behavior did not agree with experiments, due to the classical formulation of the chosen EoS. In a later work [17], the same authors provided a temperature-dependent model for the influence parameter that provided critical exponents closer to experimental values, thus improving the description of equilibrium densities and interfacial tensions near the critical point. Miqueu et al [18] employed the DGT and the Peng-Robinson EoS with volume corrections for the calculation of interfacial tensions of hydrocarbons, gases and refrigerants.…”

“…In this sense, we perform here a methodical application of the crossover soft-SAFT equation [30,31] coupled with DGT for the quantitative prediction of vapor-liquid interfacial tensions of several experimental systems, including n-alkanes, 1-alkanols, nitriles, carbon dioxide, water, and some mixtures of them. We aim to provide accurate predictions of interfacial properties far from and close to the critical region, advancing a step forward existing works in the literature [16][17][18][19][20] that employed a DGT approach, in which the description of interfacial tensions near the critical point is rather poor as a consequence of the classical formulation of the chosen EoS. In addition we search for trends to make the model as robust and predictive as possible.…”

Using a New Proposed Influence Parameter of Gradient Theory for CH4/n-alkane Binary Systems: What Advances Can Be Achieved?

“…In recent years, three groups of empirical expressions have been used to determine the influence parameter of the gradient theory: (1) constant influence parameter [6][7][8]; (2) temperature dependent influence parameter [9,10]; (3) the influence parameter based on the densities of the vapor and liquid phases [11][12][13][14][15][16]. The first group makes the theory easer.…”