Comparative study on ionic liquids and deep eutectic solvents in the separation of fuel additive isopropyl alcohol and ethyl acetate by the experimental study and molecular simulation

Due to their excellent properties, ionic liquids (ILs) and deep eutectic solvents (DESs) have become the two most widely studied extractants. In this work, the separation process of EAC and IPA was systematically investigated, the suitable ILs/DESs were preliminarily screened using the COSMO model. Then, the combination mechanism of ILs/DES-IPA was elucidated through the ESP and the electron density difference analysis. The mutual penetration distances, IGMH and AIM analysis were used to analyze the extraction mechanism. The results showed that [EMim][AC] had the best extraction capacity. Subsequently, Liquid-liquid equilibrium experiments were carried out on two selected ILs and two DESs, the order of the extraction capacity was [EMim][AC] > [EMim][H2PO4] > (ChCl-EG) > (ChCl-Gly), which was consistent with the result of theoretical analysis. Moreover, the experimental data were regressed by the NRTL model, with the RMSD were all below 0.012, indicating that the NRTL model could well predict the phase behavior of the system. In addition to providing data support for the separation design of the EAC-IPA system, this work provides a basis for the selection of extractants for the low-carbon alcohol ester system.