Dramatic Changes in the Solubilities of Ions Induced by Ligand Addition in Biphasic System D₂O/DNO₃//[C₁C₄im][Tf₂N]: A Phenomenological Study

Abstract

The solubilities of C1C4im(+) and Tf2N(-) in nitric aqueous phases have been measured for several ligand types and concentrations (0.04 M tributylphosphine oxide, 0.05 M N,N'-dimethyl-N,N'-dibutylmalonamide, 0.10 M 1-methyl-3-[4-(dibutylphosphinoyl)butyl]-3H-imidazol-1-ium bis(trifluoromethylsulphonyl)imidate, and 1.1 M N,N-dihexyloctanamide). The data evidence a significant difference between the solubilities of the cations and anions of the ionic liquid as a consequence of several ion-exchange and/or ion-pairing mechanisms involving all ions present in the system as well as the protonation/nitric-extraction ability of the ligand.

Extraction of uranium(VI) from nitric acid solutions using N,N-dihexyloctanamide in ionic liquids: Solvent extraction and spectroscopic studies

“…We adapted a published procedure [21] to determine the concentrations of NTf 2 and C n mim + ions in the aqueous phase using a 400 MHz NMR spectrometer available at Grenoble University, so the protocol is identical to that described previously. [22] In such experiments, where deuterated solvents and solutes were used, a phase inversion was observed for n = 8 above 5 M DNO 3 .The detection limit for both ions is equal to 2 mM and uncertainties are in the range of 10% (cations) and 5% (anions). C n mim + solubility values were above the detection limit for all ILs investigated and over the whole acidic range, and so were data for NTf 2 in the case of n = 4.…”

“…Because the ligand concentration is fixed in these experiments, it is implicitly included in the constants so these are conditional ones. Some additional reasonable assumptions were considered in order to get a tractable expression for D U as follows: nitrate/U(VI) complexation in the aqueous phase according to published equilibrium values, negligible DHOA protonation, as already discussed [22] and polynomial empirical variations of C 4 mim + as a function of HNO 3 (see solid line in Fig. 9).…”

Metal Extraction with Ionic Liquids-Based Aqueous Two-Phase System

“…To overcome this issue, a hydrophobic IL can be used. However, hydrophobic ILs are partly soluble in the acidic aqueous solutions from which metal ions are extracted, which results in a costly undesirable loss [14]. In addition, hydrophobic ILs are still limited, and most contain fluorinated anions which can be expensive and environmentally nonbenign [5,15].…”

Ionic‐Liquid‐Based Acidic Aqueous Biphasic Systems for Simultaneous Leaching and Extraction of Metallic Ions

“…First, the range of hydrophobic ILs is limited, most being based on fluorinated anions such as bis(trifluoromethanesulfonyl)imide,[ Tf 2 N À ], [6,7] that are expensive and refractory to biodegradation. [6,7,9] Avoiding fluorinated anions is possible by using as imple anion combined with hydrophobic cations,s uch as trihexyltetradecyl phosphonium chloride.Such ILs,however, exhibit high viscosities,a nd thus poor transport properties that hinder their industrial applicability. [6,7,9] Avoiding fluorinated anions is possible by using as imple anion combined with hydrophobic cations,s uch as trihexyltetradecyl phosphonium chloride.Such ILs,however, exhibit high viscosities,a nd thus poor transport properties that hinder their industrial applicability.…”

“…[8] Ac ollateral problem is that although hydrophobic, these ILs are partly soluble in the acidic aqueous solutions from which the metal ions are to be extracted, which induces ac ostly undesirable loss. [6,7,9] Avoiding fluorinated anions is possible by using as imple anion combined with hydrophobic cations,s uch as trihexyltetradecyl phosphonium chloride.Such ILs,however, exhibit high viscosities,a nd thus poor transport properties that hinder their industrial applicability. [10,11] Another type of extracting systems,s o-called ionic-liquid-based aqueous biphasic systems (IL-ABS) have been used in the last decade for extracting neutral compounds from an aqueous phase.…”