A ternary mechanism for the facilitated transfer of metal ions into room-temperature ionic liquids (RTILs): implications for the “greenness” of RTILs as extraction solvents

Abstract

Partitioning of sodium ions between aqueous nitrate media and 1-alkyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imides (C n mim + Tf 2 N 2 ) in the presence of dicyclohexano-18-crown-6 is shown to take place via as many as three pathways: conventional nitrato complex extraction and/or either or both of two ion-exchange processes, the relative importance of which is determined by aqueous acidity and the hydrophobicity of the ionic liquid cation. Contrary to expectations, increasing the alkyl chain length of the IL cation (from C 5 mim + to C 10 mim + ) is insufficient to eliminate the possibility of ion exchange as a mode of metal ion partitioning between the two phases, an observation with negative implications for the utility of ILs as environmentally benign extraction solvents.

Extraction of Proteins from Biological Fluids by Use of an Ionic Liquid/Aqueous Two‐Phase System

“…The extraction of metal species into the upper phase could only be facilitated in the presence of dedicated chelating reagents. [43][44][45] The effect of BmimCl and K 2 HPO 4 on BSA quantification by the Bradford method: After BSA extraction, the upper phase contains large amounts of BmimCl, while the lower phase is rich in K 2 HPO 4 . The effects of these species on the quantification of BSA were therefore investigated.…”

Synergistic Effect of 18-Crown-6 Derivatives on Chelate Extraction of Lanthanoids(III) into an Ionic Liquid with 2-Thenoyltrifluoroacetone

“…22 Many studies have investigated the possible use of an IL as an extraction solvent on the extraction of metal cations, organic compounds 22,50,51 and biomolecules. 52,53 In the use of an IL for metal cation extraction, the IL shows remarkably high performance for the extraction of alkali metals, [23][24][25][26][27] alkaline earth metals, [25][26][27][28][29][30] transition metals [31][32][33][34][35][36][37][38] and lanthanoids. [39][40][41][42][43][44][45][46] Most studies on this IL extraction system consist of the ion-exchange process with the IL cation using neutral extractants, firstly reported by Dietz and Dzielawa.…”

Selective Extraction of Copper, Mercury, Silver, and Palladium Ions from Water Using Hydrophobic Ionic Liquids

“…[15][16][17][18][19][20][21] However, because ion-exchange may occur between the metal ion and the ionic-liquid's cation, the ionic liquid may decompose in water. [22][23][24][25] Task-specific ionic liquids (TSIL), can extract cations without ion-exchange. [26][27][28] TSILs are ionic liquids with functional groups appended to the cation.…”

“…[9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] Because the properties of ionic liquids are tunable, it may be possible to identify some ionic liquids that have low viscosity, very low solubility in water, and high affinity for selected metal ions. [29][30][31][32][33][34][35][36][37][38][39][40][41] Previous reports show that ionic liquids containing imidazolium cations with alkyl chains and [PF 6 ] -anion are not useful for extraction of cations from water.…”