Activity coefficients at infinite dilution of organic solvents and water in 1-butyl-3-methylimidazolium dicyanamide. A literature review of hexane/hex-1-ene separation

•Literature review on hexane/hex-1-ene separation.•Activity coefficients at infinite dilution using GLC.•Ionic liquid 1-butyl-3-methylimidazolium dicyanamide.•High selectivity for hexane/hex-1-ene separation at T = 323.15 K.•Possible entrainer for extraction of alkenes from alkanes.

The work presented focused on the experimental data of the activity coefficients at infinite dilution, (γ13∞) of several solutes in ionic liquid of 1-butyl-3-methylimidazolium dicyanamide, [BMIM][DCA]. The values of γ13∞ for 64 solutes, including alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, water, ethers, ketones, acetonitrile, pyridine, 1-nitropropane, thiophene, and esters in [BMIM][DCA] were determined by gas–liquid chromatography at six temperatures in range of (318.15–368.15) K. The gas–liquid partition coefficients were calculated for all solutes. The partial molar excess Gibbs energy, enthalpy and entropy at infinite dilution were calculated from the experimental γ13∞ values. The [BMIM][DCA] was discussed as a solvent for the different types of separation problems with special attention to the separation of hexane/hex-1-ene, cyclohexane/cyclohexene and ethylbenzene/styrene. This work discuss a particular type of mixture made up of small hydrocarbons (alkanes) and their unsaturated counterparts (alkenes). The separating ability of the investigated ionic liquid was compared with the previously investigated 1-butyl-3-methylimidazolium-based, and dicyanoamide-based ILs for three chosen separation problems. Additionally, a literature review of γ13∞ for the hexane/hex-1-ene separation problem at T = 323.15 K is presented for the years 2010–2015. It was found that several ILs may replace conventional solvents. The proposed [BMIM][DCA] may be used as an alternative solvent for the separation of alkenes from alkanes.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide