Extraction liquid anion exchangers

Certain long-chain alkylammonium salts, notably tricaprylmethyl-ammonium chloride (Aliquat 336-S) and tri-Ao-octylamine hydrochloride (TIOA) are liquids, sometimes referred to as liquid anion exchangers, which can form extractable ion pairs or aggregates with anionic metal complexes in the... 

EDTA complexes of trivalent metals can be extracted successively with liquid anion exchangers such as Aliquat 336-S by careful pH control. Mixtures of lanthanides can be separated by exploiting differences in their EDTA complex formation constants. 

METAL EXTRACTION BY LIQUID ANION EXCHANGERS (TYPE lll-D)... 

All negatively charged metal complexes can be extracted by liquid anion exchangers, independent of the nature of the metal and the complexing ligand. Liquid anion exchange has extensive industrial application, and many examples are given in later chapters. Lists of extraction values are found in other works [e.g., 5, 21]. 

CMPO, the selective extractant chemistry in TRU-Resin, can be impregnated into polymers that also contain organic fluor molecules to develop sensor materials, as described previously for crown ether and liquid anion-exchange chemistry. Actinide sensing by this approach has been described.96 135 137 Such sensor chemistries have potential for use in the development of on-line monitors. 

Horwitz, E. P., Dietz, M. L., Chiarizia, R., Diamond, H., Maxwell, S. L., and Nelson, M. R., Separation and preconcentration of actinides by extraction chromatography using a supported liquid anion exchanger Application to the characterization of high-level nuclear waste solutions, Anal. Chim. Acta, 310, 63-78, 1995. 

Bandyopadhyay and Das [151] extracted mercury from soils with the liquid anion exchanger Aliquat-336 prior to determination by cold vapour atomic absorption spectrometry. 

Complex formation is studied experimentally by liquid-liquid extractions, or anion exchange separations. For a simple complex MLn, the cumulative complex formation constant... 

Sterri, S.H., Fonnum, F. (1978). Isolation of organic anions by extraction with liquid anion exchangers and its application to micromethods for acetylcholinesterase and 4-aminobutyrate aminotransferase. Fur. J. Biochem. 91 215-22. 

Some amines which extract anions from aqueous solutions as ion pairs are called liquid anion exchangers [40,41]. They are marketed commercially under such trade names as Aliquat-336 and Amberlite LA-1. They are mixtures of secondary or tertiary amines, or quaternary ammonium salts, with alkyl groups having 7-12 carbon atoms. 

Thorium is one of the few multivalent metals [others are Au(III), Ce(IV), U(VI), and Cr(VI)] which are extractable as nitrate complexes from nitric acid solutions [25-28]. The extractants used include TBP in CCI4 [26,29], TOPO in cyclohexane, toluene or xylene [25,30,31], and triphenylarsine oxide in CHCI3 [27]. Other reagents used for extraction of the nitrate complex of thorium include dibutyl dithiophosphate in various organic solvents [32], dibutyl sulphoxide in xylene [28], and bis(2-butoxyethyl) ether [33].The liquid anion-exchanger Aliquat 336 in xylene [34] and a solution of tertiary ammonium salt (Hyamine) in dichloroethane [35] have been also proposed for extraction of Th. The presence of Li, Na, or A1 nitrate improves the extraction of thorium. Sulphate, phosphate, and tartrate do not interfere, but fluoride must be masked, e.g., by aluminium. Thorium has been separated from U and Pu with the use of Alamine 336 and TOPO (in xylene or cyclohexane) [36]. 

The methods used by the participants are summarised in table 8.28. In the case of ETAAS detection, extraction was generally performed with liquid anion exchange solution (Amberlite LA 2/MIBK). 

Dilution with HCOC/H COj buffer addition of known amount of Cr(III)- Cr(Vl) enriched spike extraction with liquid anion exchange solution (Amberlite LA-2/M1BK) back-extraction of Cr(Vl) with ammonia solution electrodeposition on Pt wire in ammonia solution detection by IDMS of masses 52 and 53 (Lab. 11)... 

The net result is that the liquid tertiary amine has acted as anion exchanger between the anions A and B . Therefore, the extracting amine can also be designated as a liquid anion-exchanger. 

In the examples considered above, use has been made of liquid anion-exchangers for extraction by ion-pair formation. Use can also be made of liquid cation-exchangers for extraction by ion-pair formation and the mechanism of such an extraction is represented below. 

The most important liquid anion exchangers for commercial use are quaternary asemonium salts and primary, secondary, and tertiary amities, which become anion exchangers hy combining with mineral ncids to fomi alkyl ammonium salts. In the former case, ench a mstai extraction reaction might he written... 

Amine extraction. As explained in Sec. S.4, long-chain organic amines act as liquid anion-exchange media for the uranyl sulfate complex anion throu a reversible reaction such as... 

Tetra-n-butyl, -pentyl, -hexyl, and -heptyl ammonium iodides, dissolved in benzene or chloroform, can be used to extract TcOj from aqueous solutions. Such cations act as liquid anion exchangers. Distribution coefficients are compared in Table 7.3.A. 

When using GC organic acids are typically transferred into an organic solvent followed by derivatization, which makes organic acids suitable for GC measurement. Exceptions are direct aqueous injections of water samples (e.g., wastewater) onto specialty GC columns (Section II.C.l). Transfer into organic solvent may be achieved by liquid-liquid extraction, evaporation at high pH and subsequent solvent addition, solid-phase extraction on anion exchange resins and subsequent elution with solvents, or aqueous derivatization followed by extraction (Section II.B.3.a). 

Minoia et al. (1983) used a liquid anion exchanger Amberlite LA 1 or LA 2 in isobutyl methyl ketone and 6 mol/L HCI mixture, which was added to the aqueous biological specimen (in casu urine). After extraction of the anions, centrifugation and separation of both phases, all Cr(VI) was bound to the organic phase, whereas Cr(lll) was present in the aqueous phase. 

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