Studies on the selective transport of organic compounds by using ionic liquids as novel supported liquid membranes

Luís C. Branco, João G. Crespo, Carlos A. M. Afonso

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162 Citations (Scopus)


The possibility of using room-temperature ionic liquids (RTILs) in bulk (nonsupported) and supported liquid membranes for the selective transport of organic molecules is demonstrated. A systematic selective transport study, in which 1,4-dioxane, propan-1-ol, butan-1-ol, cyclohexanol, cyclohexanone, morpholine, and methylmorpholine serve as a model seven-component mixture of representative organic compounds, and in which four RTILs based on the 1-n-alkyl-3-methylimidazolium cation (n-butyl, n-octyl, and n-decyl) are used together with the anions PF6-or BF4-, immobilized in five different supporting membranes, confirms that the combination of the selected RTILs with the supporting membranes is crucial to achieve good selectivity for a specific solute. The use of the RTIL 1-n- butyl-3-methylimidazolium hexafluorophosphate, immobilized in a polyvinylidene fluoride membrane, allows an extremely highly selective transport of secondary amines over tertiary amines (up to a 55:1 ratio). The selective transport of a given solute through the RTIL/membrane system results from the high partitioning of the solute to the liquid membrane phase which, in the case of amines, is rationalized mainly by the formation of a preferential substrate/H-C(2) hydrogen bonding to the imidazolium cation.

Original languageEnglish
Pages (from-to)3865-3871
Number of pages7
JournalChemistry - A European Journal
Issue number17
Publication statusPublished - 2 Sep 2002


  • Amines
  • Ionic liquids
  • Liquid membranes
  • Selective transport
  • Separation processes


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