Modulating ILs' components solubilities in aqueous-ionic liquid biphasic systems: a Q−NMR investigation
Résumé
Aqueous−ionic liquid (A−IL) biphasic systems have been examined in terms of deuterated water, acid and IL cation and anion mutual solubilities in the upper (water-rich, in mole fraction) and lower phase of aqueous/IL biphasic systems, at ambient temperature. The biphasic mixtures were composed of deuterated acids of various concentrations (DCl, DNO 3 , DClO 4 from 10-2 to 10-4 M mainly) and five ionic liquids of the imidazolium family with hydrophobic anion (CF 3 SO 2) 2 N-, viz. [C 1 C n im][Tf 2 N], (n = 2, 4, 6, 8 and 10). Analytical techniques applied are 1 H NMR, 19 F NMR, Karl-Fischer titration, pH-potentiometry for ILs' cation and anion, water and acid determination, respectively. The effects of ionic strength (μ = 0.1 M NaCl and NaNO 3 as well as μ = 0.1 M, 0.2 M and 0.4 M NaClO 4 according to the investigated acid), the nature of the IL cation as well as the nature of the mineral acid on the solubilities of (D 2 O, D + , Tf 2 N-, C 1 C n im +) entities in the lower or upper phases were determined. Addition of sodium perchlorate enhances Tf 2 N-solubility, while it inhibits ILs' cation solubility. Differences in ILs' cation and anion solubilities up to 42 mM have been evidenced. Consequences for aqueous biphasic system characterization, solvent extraction process of metal ions and ecological impact of ILs are discussed.
Domaines
Chimie
Origine : Fichiers produits par l'(les) auteur(s)
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