Isobaric Liquid–Liquid Equilibrium Measurements and Thermodynamics Modeling for Systems: Benzene + Cyclohexane + DESs at 303.15 and 323.15 K

In this work, three deep eutectic solvents (DESs), which are sulfolane + tetrabutylammonium bromide 3:1 (molar ratio, ST3:1), sulfolane + tetrabutylammonium bromide 7:1 (molar ratio, ST7:1), and ethylene glycol + trimethylamine hydrochloride 5:1 (molar ratio, ET5:1), were prepared and used as extractants for the separation of benzene and cyclohexane mixture by liquid–liquid extraction. Liquid–liquid equilibrium (LLE) data for the three ternary systems of benzene + cyclohexane + DESs were measured at 303.15 and 323.15 K under atmospheric pressure. The Othmer–Tobias equation was used to validate the consistency of the experimental tie-lines data and the regression coefficients R2 were all close to 1. Meanwhile, distribution coefficient (β), selectivity (S), and performance index (PI) were used to evaluate the performance of the three DESs, and the result indicates that the DESs ST3:1 and ST7:1 as extractants are more feasible for the separation of benzene and cyclohexane mixture compared to ET5:1. In addition, the nonrandom two-liquid (NRTL) model was used to correlate the LLE data of the ternary systems, and the binary interaction parameters of the NRTL model were obtained