Coloured liquid anion-exchangers

Of the several stable and coloured uninegative ions examined, trans-bis(dimethylglyoximato) dinitritocobaltate(III) ([Co(C₄H₇O₂)₂(NO₂)₂]^-, termed goldenate ion, G^-) can advantageously replace the erdmannate ion in the formation of a more photochemically stable coloured anion-exchanger derived from Aliquat-336 chloride. Quantitative spectrophotometric measurements of its displacement by chloride, bromide and perchlorate ions were made and are discussed together with literature data to examine the effect of parameters such as the nature of the cation and of the anion and change in the organic solvent on the relative and absolute values of extraction constants.     

Extraction of catechol violet, chrome azurol S and eriochrome cyanine R with chloroform solutions of liquid anion-exchangers

The extraction of Catechol Violet, Chrome Azurol S and Eriochrome Cyanine R with chloroform solutions of tri-n-octylamine (TOA), TOA hydrochloride and Aliquat 336 has been investigated. From the extraction isotherms, absorption spectra of the organic phases and dependence of the extraction coefficients on extractant concentration, it was found that the singly-charged anions HL(-) are extracted preferentially, but acidic groups other than sulphonate can also form ion-pairs with alkylammonium cations at higher pH values of the aqueous phase, and at high acidity these dyes can be extracted other than by an anion-exchange reaction. The three dyes (especially Eriochrome Cyanine R and Chrome Azurol S) were strongly extracted with the liquid anion-exchanger used and Aliquat 336 was a better extractant than TOA or TOA hydrochloride. The absorption spectra for the organic phases containing Chrome Azurol S and Eriochrome Cyanine R depended on the extractant used.     

Liquid-liquid extraction of thorium from malonate solution with liquid anion-exchangers

Thorium is quantitatively extracted with 4% Amberlite LA-1 or LA-2 in xylene, from 0.01M malonic acid medium at pH 3.0 and stripped from the organic phase with 1M hydrochloric acid, then determined spectrophotometrically at 545 nm as its complex with thoron. It is separated from other elements by selective extraction and stripping.     

Extraction and separation studies of uranium/VI/with tris-/2-ethyl hexyl/phosphate

A solvent extraction method is proposed for the extraction and separation of uranium from salicylate media using tris-/2-ethyl hexyl/ phosphate dissolved in xylene as an extractant. The optimum conditions were evaluated from a critical study of pH, salicylate concentration, extractant concentration, period of equilibration and diluent. The method permits the separation of uranium from thorium, cerium, titanium, zirconium, hafnium, copper, vanadium and chromium from binary mixtures and is applicable to the analysis of uranium in synthetic samples. The method is precise, accurate, fast and selective.     

The extraction of manganese (II) from aqueous thiocyanate solutions with liquid anion-exchangers

Summary Manganese(II) is efficiently extracted from acidified thiocyanate solutions by alamine and, even more effectively, aliquat dissolved in e.g. toluene or CCl₄. The metal-containing species present in the organic extracts is Mn(NCS) ₄ ^2– .

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Extraktion von Mangan (II) ans wäßrigen Thiocyanatlösungen mit flüssigen Anionen-Austauschern

Zusammenfassung Mit Hilfe von Alamin oder besser Aliquat, gelöst z.B. in Toluol oder Tetrachlorkohlenstoff, kann Mangan(II) mit gutem Erfolg aus sauren Thiocyanatlösungen extrahiert werden. Mn ist in den organischen Extrakten als Mn(NCS) ₄ ^2– enthalten.

     

Liquid-liquid extraction of cadmium(II) from aqueous thiocyanate solutions with liquid anion-exchangers

An investigation has been made on the system liquid anion-exchanger-Cd(II)-NCS⁻. The influence of the acidity and thiocyanate concentration of the aqueous phase on the extraction has been studied. Using various methods of analysis, it has been shown that the complex anion present in the organic extracts is Cd(NCS) ₄ ²⁻ . Details are given concerning the removal of traces of Zn(II) from Cd(II)-containing solutions, and the quantitative separation of Cd(II) from Cr(III).     

Chromatographic separation of uranium

Summary A solvent mixture of methanol and saturated ammonium acetate solution (18:2) is employed for the separation of uranium in ppm quantities from iron (up to 1000 fold excess) by paper chromatography. The separation from both iron and copper can be achieved by using a solvent mixture of methyl ethyl ketone, acetic acid, and diluted nitric acid (1613).

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Zusammenfassung Zur papierchromatographischen Trennung von ppm-Mengen Uran von Eisen (in bis zu 1000 fächem Überschuß) wird ein Laufmittel aus Methanol und gesätt. Ammoniumacetatläsung (182) benutzt. Die Trennung von Eisen und Kupfer wird mit einem Gemisch aus Methyläthylketon, Essigsäure und verd. Salpetersäure (1613) durchgeführt.

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The author is highly thankful to Prof. Bh. S.V. Raghava Rao for his valuable suggestions and guidance throughout the progress of this work.Thanks are also due to the Department of Geology, Andhra University for supplying the samples and to the Counsil of Scientific and Industrial Research, New Delhi for the award of a fellowship.     

Extraction chromatography of uranium with dioctyl sulphoxide

Uranium(VI) is quantitatively extracted from aqueous perchlorate media into dioctyl sulphoxide in 1,2-dichloroethane. The extracted species contains four sulphoxides for each uranium. Most other metal ions are not appreciably extracted. On columns containing a solid support impregnated with dioctyl sulphoxide in 1,2-dichloroethane, uranium(VI) may be separated quantitatively from metal ions such as thorium(IV), zincronium(IV) and rare carths(III).     

Sorption of uranium on lead hydroxyapatite

The uranium sorption from diluted aqueous solution onto lead hydroxyapatite was studied by using a batch-mode technique and the fluorimetric determination of uranium mass concentration. Partially crystallised lead hydroxyapatite [Pb₁₀(PO₄)₆(OH)₂] was obtained by direct precipitation and mild heating. This material presents very high specific surface, which is the key factor in the sorption of uranium from diluted solution. This material has a high ability to remove uranium (K _d,max from 5,661 to 18,833 ml/g, at 4 and 60 °C, respectively) in the chosen setup conditions (initial concentration of uranium 5 × 10^?6 M and pH 5.65).     

Extraction of uranium/VI/ with octylphenyl acid phosphate from nitric acid solutions and its separation from some trivalent lanthanides

Mössbauer spectra of hexakis/alkylurea/iron/III/ complexes were measured to investigate the paramagnetic relaxation in ionic compounds. The effects of iron-iron distance and temperature on Mössbauer line shape were studied in these compounds, and the results are discussed in comparison with our previous data on tris/\-diketonato/iron/III/.     

Selective separation of metal ions by use of chelate-forming resins prepared by modification of conventional anion-exchangers with spadns and orange II

Anion-exchangers loaded with SPADNS or Orange II or SPADNS + Nitroso-R salt are used for selective separation of bismuth and cadmium, which are then determined by AAS.     

Extraction with long chain amines-VII polarographic determination of uranium

A polarographic determination of uranium is described, based on the highly selective extraction of uranium(VI) with a chloroform solution of trioctylammonium chloride, followed by re-extraction of uranium into an aqueous 0·5M KCl-0·5M HCl solution, which also serves as the polarographic supporting electrolyte. In this medium, uranium(VI) is reduced at the dropping mercury electrode to give two polarographic waves, the first of which is of analytical significance. In this way it is possible to determine 50–2400 μg of uranium in 1 ml of supporting electrolyte and in the presence of large amounts of accompanying elements.     

Ion chromatography using anion-exchangers modified with dextran sulfate

Summary Retention behavior of anions and cations on anion-exchangers modified with dextran sulfate has been investigated. Retention of anions was remarkably reduced by the modification, and the retention factor decreased with decreasing eluent concentration when sodium sulfate was used as the eluent. Cations were also retained on the modified stationary phase, and alkali and alkaline-earth metal ions were separated using copper sulfate or tris(2,2′-bipyridyl)ruthenium chloride as eluent. The size of the dextran sulfate strongly affected the retention behavior of analyte ions.     

Extraction of bivalent vanadium as its pyridine thiocyanate complex and separation from uranium, titanium, chromium and aluminium

A simple method is described for the extraction of V(II) as its pyridine thiocyanate complex. Vanadate is reduced to V(II) in 1-2N sulphuric acid by zinc amalgam. Thiocyanate and pyridine are added, the solution is adjusted to pH 5.2-5.5 and the complex extracted with chloroform. The vanadium is back-extracted with peroxide solution. Zinc from the reductant accompanies the vanadium but alkali and alkaline earth metal ions, titanium, uranium, chromium and aluminium are separated, besides those ions reduced to the elements by zinc amalgam. The method takes about 20 min and is applicable to microgram as well as milligram amounts of vanadium.     

Extraction and separation of scandium salicylate with triphenylphosphine oxide

Scandium can be extracted from 5.0 × 10⁻² mol/1 sodium salicylate solution, adjusted to pH 4.0–5.0 with 0.5% triphenylphosphine oxide dissolved in toluene as an extractant. After stripping from the organic phase with 0.5 mol/1 HCl it can be subsequently determined spectrophotometrically with Alizarin Red S. The method permits a separation of Sc(III) from Ti(IV), V(V), Cr(VI), Fe(III), Y(III), La(III), Ce(III), Nd(III) and Sm(III) in synthetic mixtures. The method is fast, simple and selective.     

Extraction separation of cadmium and zinc with tetra-n-butylammonium iodide

Tetra-n-butylammonium iodide (TBAI) forms associations in chloroform and aqueous solutions. A TBAI solution in chloroform extracts hydroiodic acid by addition. From 0.5M hydroiodic acid medium cadmium is quantitatively extracted into a TBAI solution in chloroform. Under these conditions zinc is not extracted. This makes possible the extractive separation of cadmium from zinc in micro-or macroamounts.     

Extraction and separation of scandium salicylate with triphenylphosphine oxide

Scandium can be extracted from 5.0 × 10^–2 mol/l sodium salicylate solution, adjusted to pH 4.0–5.0 with 0.5% triphenylphosphine oxide dissolved in toluene as an extractant. After stripping from the organic phase with 0.5 mol/l HCl it can be subsequently determined spectrophotometrically with Alizarin Red S. The method permits a separation of Sc(III) from Ti(IV), V(V), Cr(VI), Fe(III), Y(III), La(III), Ce(III), Nd(III) and Sm(III) in synthetic mixtures. The method is fast, simple and selective. Received: 6 May 1996 / Revised: 21 July 1996 / Accepted: 25 July 1996     

Anion-exchange separation of uranium from the lanthanidfs

The anion-exchange behavior of uranium and the lanthanides in acetie acid-organic solvent mixtures is described. The distribution coefficients of the elements in 13 organic solvents containing acetic acid as the coniplexing agent were measured, and methods for the quantitative separation of uranium, from the rare-earth elements are proposed.     

Cation-exchange separation of uranium in dimethylsulphoxide medium

Cation-exchange chromatography in a dimethylsulphoxide (DMSO) medium is a suitable means for separating uranium from metal ions, including copper, iron, nickel and molybdenum. Quantitative separations of uranium from 26 elements can best be effected on a column of Dowex 50W-X8 (200-400 mesh), using as the eluent a 20% v/v DMSO solution which is 0.6Min hydrochloric acid and 0.25M in sodium acetate. Only calcium is eluted with the uranium and all other elements studied are eluted either before or after uranium. The elution characteristics of uranium and of other metal ions were investigated with respect to changes in eluent and resin compositions. Separations were much less effective at higher concentrations of sodium ion or DMSO. None of the organic solvents methanol, ethanol, methyl glycol, acetone, dioxan or acetic acid was found to produce favourable separation conditions. Results with Dowex 50 resins of lower or higher cross-linkage were inferior to those obtained with the X8 resin.