CD shopping page |
2011-Sustainable Industrial Processing Summit
|
| Editors: | Florian K |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2012 |
| Pages: | 630 pages |
| ISBN: | 978-0-9879917-2-0 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
Solvation And Complexation Of Ions In Ionic Liquids: Spectroscopic And Theoretical Studies
clotilde gaillard1;1CNRS, villeurbanne, France;
Type of Paper: Regular
Id Paper: 188
Topic: 6
Abstract:
The aim of our work is to understand, on experimental and theoretical bases, why Room-Temperature Ionic Liquids (RTILs) that are immiscible with water can be so specific in terms of solvation, complexation and extraction of both cations and anions. RTILs, being by definition composed exclusively of ions, display unique and unusual (as compared to molecular solvents, either polar -water- or non polar -hexane-) features as far as complexation and extraction processes are concerned. In particular, they have a great potential for liquid/liquid extraction of metallic moieties, often displaying much higher extraction efficiencies compared to conventional organic media. So far, the best choice (“solvent design”) of the cation / anion components of the RTIL for a given process (liquid/liquid extraction, catalysis, organic synthesis) remains empirical and hampered by the very limited knowledge of the microscopic state and solvation of solutes in RTILs, thus requiring more fundamental studies. We thus have carried out investigations on the solvation, complexation and extraction abilities of hydrophobic RTILs towards the cation UO22+, and the anion ReO4- (the non-radioactive homologue of TcO4-) that are both of industrial relevance to the nuclear fuel cycle. Investigations are led by coupling experimental techniques (UV-visible spectroscopy, TRLFS, EXAFS) to molecular dynamics calculations. In this presentation, we will focus on the results obtained on the complexation phenomena evidenced between UO22+ and ReO4- in hydrophobic ionic liquids (C4mimTf2N, Me3BuTf2N, Bu3MeTf2N), and compare it with results obtained in more conventional solvents, i.e. water and acetonitrile. The stoechiometry of the limit complexes formed was shown to depend on the solvent, and in particular, is different between an imidazolium- and a tetra-alkyl-based RTILs. Those experimental results are compared and supplemented with molecular dynamics calculation which allowed to gain insights on the solvation of cationic and anionic species in RTILs.