Measurement and modeling of isobaric vapor – Liquid equilibrium and isothermal interfacial tensions of ethanol + hexane + 2,5 – Dimethylfuran mixture

Abstract

Isobaric vapor-liquid equilibrium data have been measured for the ternary system ethanol + hexane + 2,5 – dimethylfuran at 94 kPa and in the temperature range 330–344 K. Equilibrium determinations were performed in a vapor-liquid equilibrium still with circulation of both phases. The dependence of interfacial tensions of the ternary mixture on concentration was also experimentally determined at atmospheric pressure and 298.15 K, using the maximum differential bubble pressure technique. From the experimental results, it follows that the ternary mixture exhibits positive deviation from ideal behavior. Furthermore, the determined interfacial tensions exhibit negative deviations from the linear behavior, and ternary aneotropy is observed. The vapor-liquid equilibrium (VLE) data of the ternary mixture past the consistency test and were well correlated by Redlich–Kister expansion and predicted by the nonrandom two-liquid (NRTL), Wilson and universal quasichemical (UNIQUAC) activity coefficient models using binary parameters only. The interfacial tensions (IFT) were smoothed using the Myers-Scott expansion, showing an important contribution of parameters that describe three-body interactions, thus suggesting that the ternary interfacial tensions data cannot be initially predicted from the binary contributions. The experimental isobaric VLE and isothermal IFT data of the ternary mixture were accurately characterized by applying the linear square gradient theory to the Peng–Robinson Stryjek–Vera equation of state (EoS) appropriately extended to mixtures by means of the modified Huron–Vidal mixing rule. This model allows directly transferring the experimental excess Gibbs energy function to the EoS model for equilibrium and interfacial tension calculation purposes. This theoretical framework shows that both experimental VLE and IFT data can be accurately predicted by using binary contributions and provide a route to interpolate values phase equilibrium and interfacial tension.