Determination of pK aIL values of three chelating extractants in ILs: Consequences for the extraction of 4f elements
No Thumbnail Available
Date
2015-04-01
External link to pdf file
https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84939957015&origin=inward
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Abstract Aqueous-ionic liquid biphasic systems have been examined in terms of water and acid solubilities in the IL-rich phase at ambient temperature. The biphasic mixtures were comprised of acids of various concentrations (H+; Cl-, H+; NO3-, H+; ClO4-, mainly from 1 × 10-2 to 1 × 10-4 mol·dm-3) and four ionic liquids of the imidazolium family [C1C n im][Tf2N] (n = 4, 6, 8 and 10). The effects of ionic medium (μ = 0.1 mol·dm-3, by use of Na+; Cl-, Na+; NO3- or Na+; ClO4-, according to the acid investigated), the nature of the IL cation as well as the nature of the acid on the mutual solubilities of (H2O, H+, [C1C n im]+ and [Tf2N]-) entities were determined. Then, three chelating compounds (HL), which belong to the β-diketone family (thenoyltrifluoroacetone (HTTA), 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one (HP) and 4-benzoyl-3-phenyl-5-isoxazolone (HPBI)), were added to [C1C4im][Tf2N] and subsequent determination of the H+ distribution between the two phases allowed the determination of their dissociation constants (pK aIL) in the water-saturated ionic liquid phase. A very strong effect of the IL cation on the HTTA pK aIL value was observed from n = 4 to n = 10. The influence of this phenomenon on the lanthanide extraction process is discussed.