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Metathesis of Ionic Liquids: Continuous Ion Exchange by Donnan Dialysis
Author(s) -
Keil Philipp,
Schwiertz Manuel,
König Axel
Publication year - 2014
Publication title -
chemical engineering and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.403
H-Index - 81
eISSN - 1521-4125
pISSN - 0930-7516
DOI - 10.1002/ceat.201200322
Subject(s) - chemistry , hydroxide , inorganic chemistry , ion exchange , counterion , chloride , bromide , aqueous solution , ionic liquid , membrane , ultrapure water , ion , organic chemistry , chemical engineering , catalysis , biochemistry , engineering
Ionic liquids (IL) are salts that have extraordinary low melting points below 100 °C. While only a very limited number of possible IL can be synthesized directly, the vast majority is prepared via the synthesis of a precursor IL with the desired cation and a subsequent anion exchange. This paper presents the continuous anion exchange by Donnan dialysis in aqueous solution with anion exchange membranes. The retention of the anion exchange membranes used in this work for inorganic and IL cations was found to be R > 99 %. The average integral transport coefficients were determined for the exchange of chloride/acetate, chloride/hydroxide and bromide/hydroxide for various IL and classical salts. The values of the integral average transport coefficients were found to be independent of the investigated counterions. Process modeling was applied to optimize the flow conditions to reach an anion exchange > 98 %. Ultrapure hydroxide solutions and acetates of common classes of IL cations were prepared with a conversion of the reactant anions of > 99 % and cationic impurity contents of < 1 %.