Determination and correlation of LLE data for n-hexane, ethyl acetate and different extractants

In order to separate n-hexane/ethyl acetate (EA) produced in industrial production, the liquid–liquid extraction was used to separate the azeotropic system with sulfolane, 1,2-propanediol and dimethyl sulfoxide (DMSO) as extractants. The liquid–liquid equilibrium (LLE) data of the n-hexane + EA + sulfolane/1,2-propanediol/DMSO were measured at 303.15 K, 313.15 K and 323.15 K. The extraction capacity of the extractants were evaluated by the distribution coefficient (D) and separation factor (S). The LLE data were correlated using the NRTL and UNIQUAC thermodynamic models to obtain binary interaction parameters. The root mean square deviation (RMSD) were all less than 0.02 indicating that the two models were suitable for the phase equilibrium behavior. GUI-MATLAB software was used to test the reliability of the regressed binary interaction parameters. The Dmol³ module of the Materials Studio was used to analyze σ-profile of n-hexane, EA and extractants and to assess the interaction energy between the components. The results show that sulfolane is the best extractant for the separation of n-hexane + EA.