Extraction of cytochrome c by a functionalized ionic liquid containing a crown ether

Fukiko Kubota, Yusuke Koyanagi, Kazunori Nakashima, Kojiro Shimojo, Noriho Kamiya, Masahiro Goto

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15 Citations (Scopus)


To verify the applicability of functionalized ionic liquids, so-called 'task-specific ionic liquids', to liquid-liquid extraction as solvents possessing extraction ability, we carried out the extraction of a protein cytochrome c (Cyt-c) with an ionic liquid with an attached crown ether moiety in the imidazolium cation. The functionalized ionic liquid, [18C6mim][PF 6], was dissolved in two different ionic liquids as diluents, one having a hydroxyethyl group, [C2OHmim][Tf2N], and the other an ethyl group, [C2mim] [Tf2N], respectively. The transfer of Cyt-c from the aqueous phase to the ionic liquid phase took place with [18C6mim][PF6] in the [C2OHmim][Tf2N] system. The functionalized ionic liquid with the crown ether attached provided the similar extraction behavior to that using dicyclohexano-18-crown-6 (DCH18C6) as the extradant. Although the extraction ability was lower than that of DCH18C6, the functionalized ionic liquid system gave a better stripping performance than the ordinary crown ether system. The extraction efficiency was not influenced by operating temperature when the concentration of [18C6mim] was high whereas it was greatly affected by temperature at low [18C6mim] concentration. The functionalized ionic liquids showed an extremely higher extraction performance compared to that of the ordinary ionic liquids, which have no coordination sites for the target molecule.

Original languageEnglish
Pages (from-to)115-120
Number of pages6
JournalSolvent Extraction Research and Development, Japan
Publication statusPublished - 2007

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Chemical Engineering
  • Filtration and Separation


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