I. I. Torocheshnikova

Task-specific ionic liquid trioctylmethylammonium salicylate as extraction solvent for transition metal ions

A quaternary ammonium-based room temperature ionic liquid trioctylmethylammonium salicylate (TOMAS) has been studied as an extractant of transition metal ions (Fe(3+), Cu(2+), Ni(2+), Mn(2+)) in aqueous solutions. The effect of pH value on the recovery of metal ions has been investigated. The mechanism of extraction into the ionic liquid has been proposed. The possibility of stripping voltammetric determination of transition metals in aqueous solutions using TOMAS-modified electrodes has been demonstrated.

18-Crown-6 and dibenzo-18-crown-6 assisted extraction of cesium from water into room temperature ionic liquids and its correlation with stability constants for cesium complexes.

The pH-profiles of the extraction of Cs+ into four conventional (1-butyl-3- methylimidazolium hexafluorophosphate and bis[trifluoromethyl)sulphonyl]imides of 1- butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, and 1-(2-ethylhexyl)-3-methylimidazolium) and two novel (trioctylmethylammonium salicylate and tetrahexyl-ammonium dihexylsulfosuccinate) room temperature ionic liquids have been determined both in the absence and in the presence of crown ether (18-crown-6 or dibenzo-18-crown-6). The pH-profiles of distribution ratio of crown ethers have been established in the same conditions. The relationship of cesium extraction efficiency both with the stability of its complexes with crown ethers and crown ethers’ distribution ratio has been clarified.

Phosphoryl containing podands as carriers in plasticized membrane electrodes selective to quaternary ammonium surfactants

Open chain polyethers with phosphoryl-containing terminal groups have been studied as carriers in plasticized membrane electrodes that are selective towards cationic surfactants. Host–guest complexation has also been studied by means of batch extraction and bulk membrane transport experiments. For the various guests, the bulk membrane (chloroform) transport rate decreases in the series tetraalkyl ammonium > alkyl pyridinium > alkyl ammonium, while the series of solvent extraction efficiency is exactly opposite; an explanation for this behaviour is proposed. The performance of electrode membranes follows the series for bulk membrane transport. Among the ISE membranes of various composition, one containing the longest (seven oxygen atoms) podand, o-nitrophenyl octyl ether (plasticizer), and sodium tetraphenyl borate (anionic additive) performs the best. The slope of the electrode function equals 58.5 mV/decade, the detection limit for dodecyltrimethylammonium is 3.2 × 10-6 M. ISE response time is 5–10 s, the working pH range is 2–11 and lifetime is at least 6 months. The electrode selectivity is significantly better than that of conventional ion-association and crown ether based electrodes.

Thermodynamics of complexation of cesium ions with dibenzo-18-crown-6 in hydrophobic ionic liquids

The stability constants of the [Cs(DB18C6)]+ complex (DB18C6 is dibenzo-18-crown-6, L) in hydrophobic ionic liquids (room-temperature ionic liquids, RTIL) trioctylmethylammonium salicylate ([TOMA][Sal]), tetrahexylammnoium dihexylsulfosuccinate ([THA][DHSS]), and 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([BMIM][N(Tf)2], as well as of the [Cs(18C6)2]+ complex in [BMIM][N(Tf)2], were measured by 133Cs NMR in the temperature range 27–57°C. The changes in the enthalpy and entropy of complex formation were determined. A linear correlation was revealed between logK1 and the extraction factor logDCsDB18C6 for the cesium extraction from an aqueous solution into the RTIL.

Extraction of Nitrates of Alkali and Alkaline Earth Metals with Crown Ether into Hydrophilic Ionic Liquid in the Presence of Salting out Agent

We show that the hydrophilic liquid N-butyl-4-methylpyridinium tetrafluoroborate is suitable for the extraction of metal ions with dicyclohexyl-18-crown-6. We used magnesium sulfate as salting-out agent, resulting in the formation of two immiscible phases in the ionic liquid-water system. The pH profiles of the extraction of alkali and alkaline earth metals have been determined; the influence of the concentration of the salting-out agent on recovery has been investigated.

Extraction of amino acids with di(2-ethylhexyl)phosphoric acid in the presence of dicyclohexyl-18-crown-6

Extraction of amino acids from aqueous solutions into chloroform with di(2-ethyl-hexyl)phosphoric acid was studied. The extraction efficiency decreases in the sequence Trp>Phe>Leu>Arg>Lys>He>Ala>Gly. The addition of dicyclohexyl-18-crown-6 improves the efficiency and kinetics of extraction of most amino acids. The extraction degree depends on the concentration of the crown ether.

Transport of carbohydrates across a bulk liquid membrane with substituted calyx[8]arenes and phosphoryl-containing podand

Adamantyl- andtert-butyl-substituted calyx[8]arene esters and tripodal podand containing diphenylphosphoryl terminal groups are capable of transporting monosaccharides, but not disaccharides, across a bulk chloroform membrane. Both stoichiometry of complex formation and transport selectivity, in particular, glucose-fructose selectivity, are sensitive to the structure of a carrier.

Extraction of cadmium, lead, cobalt, copper, and zinc ions from aqueous solutions into hydrophilic–hydrophobic ionic liquids

Extraction of cadmium(II), lead(II), cobalt(II), copper(II), and zinc(II) into ionic liquids tetraoctylammonium N-lauroyl sarcosinate and trioctylmethylammonium salicylate is studied. Cadmium(II), lead(II), copper(II) in tetraoctylammonium N-lauroyl sarcosinate and copper(II) in trioctylmethylammonium salicylate are quantitatively extracted from neutral and weakly alkaline solutions in the absence of additional reagents. The effect of the composition of aqueous and organic phases, as well as the contact time, on metal extraction is investigated.