NMR Study on the Possible Interactions Between Imidazolium Based Ionic Liquids and Extractants Widely Applied in Solvent Extraction and Separation of f-Ions

Thenoyltrifluoroacetone: Preferable Molecule for Solvent Extraction of Metals—Ancient Twists to New Approaches

A review of the investigations devoted to the solvent extraction processes of metal ions with a chelating ligand thenoyltrifluoroacetone (HTTA) is presented herein. It seems that this molecule has been preferred in the field for more than half a century, and that it is used very often as an extractant for almost all metals. The main objective of the present review is also to provide an overview of the synergistic solvent extraction of lanthanoids, particularly with the use of a β-diketone−neutral mixture. Based on the previous published results in the open literature, the extraction efficiency has been examined in detail and discussed further mainly in terms of the corresponding equilibrium constants among other outlined, so-important parameters. Major conclusions on the role of ligating groups of extractants towards the mechanism, an improved extraction enhancement, and selectivity are additionally provided. The fact that ionic liquids (ILs) appear to be replacing volatile diluents in the field of the liquid–liquid extraction of metals, again with the participation of this β-diketone, is not surprising. As is well known, a very efficient and simple way to determine the stoichiometry of the extracted species in the organic phase is by the simple use of the slope analysis method; however, it is sometimes difficult to perform, either because it somehow requests good solubility of the ligand or because obtained slopes are quite often far from integer values in ILs.

Distribution of N-Methylimidazole in Ionic Liquids/Organic Solvents Systems

The partition coefficients, Kmim, of N-methylimidazole (mim) in two-component systems composed of ionic liquid (IL) and a series of organic solvents immiscible with ILs (butyl acetate, ethyl acetate, tert-butyl methyl ether, diethyl ether and cyclohexane) were determined by a shake-flask method. The influence of different factors such as temperature, solvent polarity, mim concentration, and water content on Kmim by using 1-butyl-3-methylimidazolium chloride {[C4C1im]Cl} as a model compound was comprehensively studied. The calculated thermodynamic functions of transfer (∆trG0, ∆trH0, ∆trS0) showed that the mim migration (IL→organic phase) is a thermodynamically unfavorable and enthalpy-determined process in the temperature range of 298.15 to 328.15K; however, the results suggested that mim partition toward the organic phase can be enhanced by the rational manipulation of the extraction conditions. Experiments conducted with other 1-alkyl-3-methylimidazolim chlorides (CnC1im]Cl (n = 6, 8, 10) revealed that mim possesses similar behavior and can be successfully washed out from the ILs by extraction with organic solvents. The results obtained in this study give some clues toward the choice of an appropriate solvent and conditions to be employed for the purification of halide-based ILs by means of a liquid-liquid extraction.

The interaction of extractants during synergistic solvent extraction of metals. Is it an important reaction?

The target of the review is to provide an overview on the possible interaction between the two ligands during synergistic solvent extraction of metallic species.

Synergism as a phenomenon in solvent extraction of 4f-elements with calixarenes

The objective of the review is to provide an overview on the synergistic solvent extraction of lanthanoids: β-diketone/calixarene mixtures.