Aqueous N-H acid bis(trifluoromethylsulfonyl) imide Solution - [C4mim][Tf2N] Ionic Liquid Biphasic System: an Original Investigation by Diffusion Ordered Spectroscopy Nuclear Magnetic Resonance

International audienceTransfers of solutes from an aqueous phase to an ionic liquid phase and vice versa has been well studied for years. On the other hand, influence of transferred solutes on the ionic liquid's structure is not yet evaluated. Therefore, we focus on the aqueous-ionic liquid biphasic system composed of two immiscible phase containing N-H acid bis(trifluoromethylsulfonyl) imide and [C 4 mim][Tf 2 N] ionic liquid. After mixing and separation of the two phases, a part of water, H 3 O + , [Tf 2 N-] and H[Tf 2 N] anions were transferred into [C 4 mim][Tf 2 N] ionic liquid phase. The presence of this solutes could modify the local structure of [C 4 mim][Tf 2 N] ionic liquid. So far, our goal is to evaluate this structural change using several tools. For this, one dimensional 1 H, 19 F and Diffusion Ordered Spectroscopy Nuclear Magnetic Resonance were carried out on the [C 4 mim][Tf 2 N] phase. We observed that some of water molecules were free and formed local microstructure as water pocket inside the ionic liquid frame. The others were hydrogen bonded to [Tf 2 N-] anions or H[Tf2N]. The N-H acid bis(trifluoromethylsulfonyl) imide has a salting in effect and the biphasic system turn in a single phase for [H[Tf 2 N]] aq, init = 3 M. The network of [C 4 mim][Tf 2 N] ionic liquid is gradually destroyed when the water brought by the acid H[Tf 2 N] becomes the major species

Aqueous acidic solution - ionic liquid biphasic system: An original investigation by diffusion ordered spectroscopy nuclear magnetic resonance

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Modulating ILs' components solubilities in aqueous-ionic liquid biphasic systems: a Q−NMR investigation

International audienceAqueous−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

Effect of hydrophobic ionic liquids aqueous solubility on metal extraction from hydrochloric acid media: Mathematical modelling and trivalent thallium behavior

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Extraction of actinides by tertiary amines in room temperature ionic liquids: evidence for anion exchange as a major process at high acidity and impact of acid nature

International audienceExtraction of U(VI) and Pu(IV) using several tri-alkylamines such as tri-n-butylamine (TBA), tri-n-hexylamine (THA), tri-n-octylamine (TOA), and tri-iso-octylamine (TiOA) in room temperature ionic liquids, [Cnmim][Tf2N] (where n = 4, 6 or 8), was investigated from nitric acid as well as hydrochloric acid medium. In the absence of the amines, the extraction results indicated an increase in the extraction of both U(VI) and Pu(IV) as a function of the acid concentration which was attributed to the extraction of probable anionic species such as UO2X3−, UO2X42−, PuX5− and PuX62−(where X = Cl− or NO3−) according to an anion-exchange mechanism involving Tf2N− ions. The presence of amines in the ionic liquid enhances the extraction of the metal ions with increased HCl concentration, especially in the case of UO22+, but the amines appear to be almost inefficient in HNO3 medium. This is ascribed to the protonation/association of amines via solubilization of H+ and NO3− ions in the ionic liquid phase in the case of nitric medium, while hydrochloric acid does not solubilize in ionic liquid, and thus the amine remains efficient. Modeling of the extraction data in HCl medium for U(VI) and Pu(IV) in the presence of amines has been performed and confirmed the anion exchange mechanism

Mutual solubility of water and hydrophobic ionic liquids in the presence of hydrochloric acid

International audiencePrevious studies have shown that the presence of nitric acid, the principal solute in various hydrometallurgical processes, and perchloric acid in the aqueous phase is an important factor for increased aqueous solubility of hydrophobic ionic liquids. In this study, the effect of hydrochloric acid in the aqueous phase on the mutual solubility of water and hydrophobic 1,3-dialkylimidazolium-and N,N-dialkylpyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquids, [C n mim][Tf 2 N] (n ¼ 2, 4, 6, and 8) and [C 3 C 1 pyrr][Tf 2 N], is examined at room temperature and atmospheric pressure. Hydrochloric acid caused a considerable increase in the aqueous solubility of all the studied ionic liquids. The amount of water transferred into the organic phase increases with increasing hydrochloric acid concentration for short alkyl chain ILs, and the opposite trend was observed for long alkyl chain ILs. The effect of the N-H acid bis(trifluoromethylsulfonyl)imide, H[Tf 2 N], and the salts lithium bis(trifluoromethylsulfonyl)imide, Li[Tf 2 N], and 1-butyl-3-methylimidazolium chloride, [C 4 mim]Cl, dissolved in hydrochloric acid solutions on the mutual solubility of water and the [C 4 mim][Tf 2 N] ionic liquid were also investigated. The salting-out effect is observed and it was shown to be dependent on the nature of the salt, its concentration and the hydrochloric acid concentration in the aqueous phase. A mathematical model has been developed to describe the dependence of the ionic liquid cation and anion concentration on the common ion salt concentration in the aqueous hydrochloric acid phase. This model describes the basic character of ionic liquid dissolution in the aqueous phase and allows for estimation of solubility product values

Effect of aqueous hydrochloric acid and zwitterionic betaine on the mutual solubility between a protic betainium-based ionic liquid and water

International audienceThe 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

Hydrophobic polymerized ionic liquids for trace metal solid phase extraction: thallium transfer from hydrochloric acid media

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Ionic liquid-based uranium( vi ) extraction with malonamide extractant: cation exchange vs. neutral extraction

International audienceWe present new insights into the extraction of uranium(VI) from a nitric acid aqueous phase into 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ionic liquid ([C 4 mim][Tf 2 N]) using a malonamide extractant, namely N,N 0-dimethyl-N,N 0-dibutylmalonamide (DMDBMA). UV-vis absorption spectrophotometry and extended X-ray absorption fine structure (EXAFS) experiments have been carried out on the extracted phases and new extraction data were used in order to model the mechanism lying behind the U(VI) extraction. We show that two different uranyl species are involved, as a function of the aqueous nitric acid concentration: the cation UO 2 (DMDBMA) x 2+ (2 # x # 3) at low acid concentration, and the neutral UO 2 (NO 3) 2 (DMDBMA) at high acid concentration. The former is extracted by exchange with 2 protons, while the latter is co-extracted with a HNO 3 molecule. We show that the uranium extraction is performed without the direct help of IL ions, although the latter pollute noticeably the aqueous phase

Extraction de l’uranium(VI) avec un mélange de TODGA et d’un liquide ionique dans un solvant moléculaire

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