Measurement and Correlation of Isobaric VLE Data for 1-Propanol + Water + 1-Butyl/Decyl-3-methylimidazole Bromide/Nitrate ILs at 101.33 kPa

Here, a novel protocol for the separation of the azeotropic system was performed by combining experimental investigations with the COSMO-RS prediction and molecular simulation to select ILs to break up the azeotropic point. The VLE data for the 1-propanol (1) + water (2) + ILs (3) azeotropic system were measured using a Fischer still at 101.33 kPa and correlated by the NRTL model. Four types of [Bmim]Br, [Bmim]NO3, [Demim]Br, and [Demim]NO3 ILs synthesized were screened to separate the azeotropic system. The affinity interaction occurred between the ILs and water, leading to the formation of the salting-out effect on 1-propanol because the ILs binding water molecules made free water molecules decrease, leading to the precipitation of 1-propanol in the pseudobinary azeotropic system. By comparison, the cations and anions of ILs for the salting-out effect are in the order as follows: [Demim]+ > [Bmim]+ and NO3– > Br–. Additionally, the descending orders of the ILs for the salting-out effect are [Demim]NO3, [Demim]Br, [Bmim]NO3, and [Bmim]Br. 30% (molar fraction) of ILs can separate the azeotropic systems by breaking up the azeotropic point.