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Studies on the Selective Transport of Organic Compounds by Using Ionic Liquids as Novel Supported Liquid Membranes
Author(s) -
Branco Luís C.,
Crespo João G.,
Afonso Carlos A. M.
Publication year - 2002
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20020902)8:17<3865::aid-chem3865>3.0.co;2-l
Subject(s) - ionic liquid , membrane , chemistry , hexafluorophosphate , alkyl , morpholine , polyvinylidene fluoride , selectivity , cyclohexanol , organic chemistry , hydrogen bond , inorganic chemistry , molecule , biochemistry , catalysis
Abstract 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 PF 6 − or BF 4 − , 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/HC(2) hydrogen bonding to the imidazolium cation.