Experimental and Modeling Study of Acetonitrile Separation from Water with Ionic Liquids: VLE Data for Binary and Ternary Systems

The vapor–liquid equilibrium (VLE) data of the binary acetonitrile + water system and three ternary systems containing ionic liquids (ILs): acetonitrile + water + 1-butyl-3-methylimidazolium chloride ([C4mim][Cl]), + 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]), and + 1-hexyl-3-methylimidazolium chloride ([C6mim][Cl]) were experimentally measured at low pressures. In addition, the literature VLE data for the binary systems acetonitrile + [C4mim][Cl], acetonitrile + [C4mim][BF4], and acetonitrile + [C6mim][Cl] were adopted for model correlation. The NRTL and e-NRTL models were employed to correlate the binary data. The experimental results demonstrate that the presence of ILs causes a pronounced salting-out effect on acetonitrile, significantly increasing its relative volatility with respect to water. The separation performance of the three ILs for the acetonitrile + water mixture decreases in the order: [C4mim][Cl] > [C6mim][Cl] > [C4mim][BF4].