Extraction of Toluene from a Toluene/n-Heptane Mixture Using Protonated Imidazolium-Based Ionic Liquids

  • Ji Yeon Lee
  • YoonKook ParkEmail author


The liquid–liquid equilibria (LLE) of the ternary system consisting of toluene, n-heptane, and ethylimidazolium bis(trifluoromethyl)sulfonylimide ([EtIM][NTf2]) were measured over the temperature range 298.2–313.2 K at ambient pressure. A binary mixture of [EtIM][NTf2] and methylimidazolium bis(trifluoromethyl)sulfonylimide ([MeIM][NTf2]) was used instead of [EtIM][NTf2] to investigate the effect of an additional ionic liquid on toluene separation from a toluene/n-heptane mixture. The LLE of a different ternary system of toluene, n-heptane, and [MeIM][NTf2] was also measured at 313.2 K and ambient pressure. Ionic liquids were not detected in the raffinate phase and thus no further separation unit for ionic liquids was required in the toluene separation process. The values of the distribution coefficient of toluene with the ionic liquids used in this study are higher than those with sulfolane at 313.2 K. This should provide a significant benefit because a higher distribution coefficient for toluene yields a more economic feed-to-solvent ratio in aromatic separations.


Ionic liquid Distribution coefficient Liquid–liquid equilibrium Selectivity Binary ionic liquid mixture 



This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Education, Science and Technology (NRF-2015R1D1A1A01056570).


  1. 1.
    Meindersma, G.W., Podt, A., de Haan, A.B.: Ternary liquid–liquid equilibria for mixtures of an aromatic+ an aliphatic hydrocarbon+ 4-methyl-N-butylpyridinium tetrafluoroborate. J. Chem. Eng. Data 51, 1814–1819 (2006)CrossRefGoogle Scholar
  2. 2.
    Sakal, S.A., Shen, C., Li, C.: (Liquid+ liquid) equilibria of benzene+ cyclohexane+ two ionic liquids at different temperature and atmospheric pressure. J. Chem. Thermodyn. 49, 81–86 (2012)CrossRefGoogle Scholar
  3. 3.
    Zhang, F., Li, Y., Zhang, L., Zhou, Z., Sun, W., Ren, Z.: Benzyl- and vinyl-functionalized imidazolium ionic liquids for selective separating aromatic hydrocarbons from alkanes. Ind. Eng. Chem. Res. 55, 747–756 (2016)CrossRefGoogle Scholar
  4. 4.
    Larriba, M., Navarro, P., Garcia, J., Rodriguez, F.: Liquid–liquid extraction of toluene from heptane using [emim][DCA], [bmim][DCA], and [emim][TCA] ionic liquids. Ind. Eng. Chem. Res. 52, 2714–2720 (2013)CrossRefGoogle Scholar
  5. 5.
    Larriba, M., Navarro, P., Garcia, J., Rodriguez, F.: Liquid-liquid extraction of toluene from n-alkanes using [4empy][Tf2N] + [emim][DCA] ionic liquid mixtures. J. Chem. Eng. Data 59, 1692–1699 (2014)CrossRefGoogle Scholar
  6. 6.
    Sumon, K.Z.: Extraction of aromatics using green solvents based on ionic liquids. Thesis, King Fahd University of Petroleum & Minerals (2005)Google Scholar
  7. 7.
    Arce, A., Earle, M.J., Rodriguez, H., Seddon, K.R., Soto, A.: Bis{(trifluoromethyl)sulfony-l}amide ionic liquids as solvents for the extraction of aromatic hydrocarbons from their mixtures with alkanes: effect of the nature of the cation. Green Chem. 11, 365–372 (2009)CrossRefGoogle Scholar
  8. 8.
    Castro, M.C., Arce, A., Soto, A., Rodriguez, H.: Liquid–liquid equilibria of mutually immiscible ionic liquids with a common anion of basic character. J. Chem. Thermodyn. 102, 12–21 (2016)CrossRefGoogle Scholar
  9. 9.
    Lee, J., Park, Y.: Usage of a deep eutectic solvent based on three compounds for toluene separation. Korean J. Chem. Eng. 35, 210–216 (2018)CrossRefGoogle Scholar
  10. 10.
    Wang, Y., Hou, Y., Wu, W., Liu, D., Ji, Y., Ren, S.: Roles of a hydrogen bond donor and a hydrogen bond acceptor in the extraction of toluene from n-heptane using deep eutectic solvents. Green Chem. 18, 3089–3097 (2016)CrossRefGoogle Scholar
  11. 11.
    Larriba, M., Navarro, P., Garcia, J., Rodriguez, F.: Separation of toluene from n-heptane, 2,3-dimethylpentene, and cyclohexane using binary mixtures of [4empy][Tf2N] and [emim][DCA] ionic liquids as extraction solvents. Sep. Puri. Technol. 120, 392–401 (2013)CrossRefGoogle Scholar
  12. 12.
    Garcia, S., Larriba, M., Garcia, J., Torrecilla, J.S., Rodriguez, F.: Liquid–liquid extraction of toluene from n-heptane using binary mixtures of N-butylpyridinium tetrafluoroborate and N-butylpyridinium bis(trifluoromethylsulfonlyl)imide ionic liquids. Chem. Eng. J. 180, 210–215 (2012)CrossRefGoogle Scholar
  13. 13.
    Kapoor, U., Shah, J.K.: Thermophysical properties of imidazolium-based binary ionic liquid mixtures using molecular dynamics simulations. J. Chem. Eng. Data 63, 2512–2521 (2018)CrossRefGoogle Scholar
  14. 14.
    Fillion, J.J., Brennecke, J.F.: Viscosity of ionic liquid–ionic liquid mixtures. J. Chem. Eng. Data 62, 1884–1901 (2017)CrossRefGoogle Scholar
  15. 15.
    Renon, H., Prausnitz, J.M.: Local compositions in thermodynamic excess functions for liquid mixtures. AIChE J. 14, 135–144 (1968)CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of Biological and Chemical EngineeringHongik UniversitySejongSouth Korea

Personalised recommendations