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The partitioning behavior of indium and thallium ions between aqueous hydrochloric acid solutions and hydrophobic betainium bis(trifluoromethylsulfonyl)imide ionic liquid was studied using a standard liquid–liquid extraction technique. The experiments were mainly carried out by means of a radiochemical method, using 111In and 201Tl medical radionuclides at an ultra-trace concentration. Both mono- and trivalent thallium were utilized and the highest oxidation state (3+) was produced by adding either chlorine or bromine water to the aqueous phase prior to extraction. The metal ion transfer was optimized by varying the aqueous concentration of hydrochloric acid and by introducing zwitterionic betaine as an extracting agent into the aqueous phase. It was found that the highest D values of In(III), Tl(III) and Tl(I) in the investigated chemical systems were up to 200, 70, and 1, respectively. The influence of the addition of lithium salt, having common with the ionic liquid counterion, and the variation of mixing time on the distribution ratio of the metal ions were also studied. To understand the underlying extraction mechanism of the metal ions and to propose the predominant extracted species, mathematical models based on ion pair formation and ion exchange were developed.

International audience; The solubility of hydrophobic betainium bis(trifluoromethylsulfonyl)imide ionic liquid in an aqueous phase with controlled acidity has been investigated by a standard liquid-liquid extraction technique. The effect of zwitterionic betaine added into the aqueous phase has also been studied. Quantitative NMR was employed to characterize the distribution behavior of the ionic liquid constituents between the two phases. A mathematical model to describe the ionic liquid solubility in the aqueous phase was developed. This approach was utilized to estimate the conditional solubility product constant of the ionic liquid. The possibility of the transfer of some dissociation products back into the organic phase was investigated. (C) 2018 Elsevier B.V. All rights reserved.

International audience; Pure hydrophobic ionic liquids are known to extract metallic species from aqueous solutions. In this work we have systematically investigated thallium (Tl) extraction from aqueous hydrochloric acid (HCl) solutions into six pure fluorinated ionic liquids, namely imidazolium-and pyrrolidinium-based ionic liquids with bis(trifluoromethanesulfonyl)imide and bis(fluorosulfonyl)-imide anions. The dependence of the Tl extraction efficiency on the structure and composition of the ionic liquid ions, metal oxidation state, and initial metal and aqueous acid concentrations have been studied. Tl concentrations were on the order of picomolar (analyzed using radioactive tracers) and millimolar (analyzed using inductively coupled plasma mass spectrometry). The extraction of the cationic thallium species Tl + is higher for ionic liquids with more hydrophilic cations, while for the TlX z 3−z anionic species (where X = Cl − and/or Br −), the extraction efficiency is greater for ionic liquids with more hydrophobic cations. The highest distribution value of Tl(III) was approximately 2000. An improved mathematical model based on ion exchange and ion pair formation mechanisms has been developed to describe the coextraction of two different anionic species, and the relative contributions of each mechanism have been determined.