JOURNAL OF CHEMICAL ENGINEERING OF JAPAN
Online ISSN : 1881-1299
Print ISSN : 0021-9592
Separation Engineering
Application of Ionic Liquids to Extraction Separation of Rare Earth Metals with an Effective Diglycol Amic Acid Extractant
Fukiko KubotaYousuke ShimoboriYuzo BabaYusuke KoyanagiKojiro ShimojoNoiho KamiyaMasahiro Goto
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JOURNAL OPEN ACCESS

2011 Volume 44 Issue 5 Pages 307-312

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Abstract

The application of ionic liquids as alternatives to conventional organic solvents in extraction processes has been actively investigated. A crucial step towards the practical use of ionic liquids is the development of extractants that work effectively within these new media. In the present study, the extraction separation of rare earth metals into ionic liquids, 1-butyl, 1-octyl, and 1-dodecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([Cnmim][Tf2N], n = 4, 8, 12), was performed using a novel extractant, N,N-dioctyldiglycol amic acid (DODGAA). Quantitative extraction of metal ions such as Y3+ and Eu3+ was selectively achieved in the presence of the base metal ion Zn2+, which was not extracted at all under the present experimental conditions. The extraction efficiency was enhanced for the shorter-alkyl-chain imidazolium ionic liquid [C4mim][Tf2N] compared to that for a conventional organic solvent system. Extraction mechanism studies elucidated that the metal extraction proceeds via proton exchange reactions between DODGAA and the metal ions in the ionic liquid (the same mechanism as in the conventional organic solvent). The stripping reaction, or recovery, of the metal ions from the extracting phase was readily accomplished with an acid solution such as nitric acid.

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© 2011 The Society of Chemical Engineers, Japan
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