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Abstract  

The distribution of tantalum(V) between 0.1M trioctylamine oxide dissolved in xylene and sulphuric acid solutions has been studied. On the basis of results on the distribution, it is concluded that at sulphuric acid concentration 0.5M, tantalum is probably extracted by a solvate mechanism as the complex Ta(OH) (SO4)2·3TOAO. It has also been shown that tantalum can be quantitatively separated from niobium, uranium, thorium and rare earth elements by extraction with N-oxide of trioctylamine from 0.5M sulphuric acid solution.

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Abstract  

The solvent extraction of cerium(III) from nitric, hydrochloric and sulphuric acid solutions by 4-(5-nonyl)pyridine oxide and trioctylamine oxide in xylene has been studied. The influence of the concentration of the solvents and salting-out agents is described. From the results of partition experiments attempts have been made to deduce the nature of the extracted species. The investigation shows that cerium(III) can be separated from cerium(IV) from very dilute solutions of mineral acids and also from moderate nitric acid media.

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Abstract  

Trace level cerium has been oxidized to the quadrivalent state with potassium dichromate and shown to be preferentially extracted from very dilute mineral acid solutions and also from moderate nitric acid media by 0.1M solutions of 4-(5-nonyl)pyridine oxide and trioctylamine oxide dissolved in xylene. The dependence of extraction on the type of N-oxide, acid concentration and the N-oxide concentration has been investigated. The influence of the concentration of salting-out agents is described. Separation factors for a number of metal ions relative to cerium(IV) are reported for 0.1 M 4-(5-nonyl)pyridine oxide/xylene-0.1M sulphuric acid system. The ratio of the D for Ce(IV) to that of Ce(III) is greater than 105, and the D for Ce(IV) is much greater than that for thorium(IV). Separation of cerium(IV) from thorium has been achieved from 0.1M sulphuric acid solutions using 0.1M 4-(5-nonyl)pyridine oxide/xylene as an extractant.

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Abstract  

The partition of tracer-level (<10−7 mole/l) platinum between various 4-(5-nonyl)-pyridine phases and aqueous nitric, hydrochloric, and sulphuric acid phases has been studied radiometrically as a function of the amine and acid concentrations. The effects of saltingout agents and some anions on the extraction of the metal are reported. The extraction data is compared with that of gold and conditions are established for the separation of daughter199Au from neutron irradiated platinum. The distribution coefficients of various metal ions are given for the 4-(5-nonyl)pyridine-10M HCl system and their factors for separation from platinum estimated.

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Abstract  

The extraction of technetium (VII) by 4-(5-nonyl)pyridine has been investigated from different aqueous solutions. Separation from uranium and some fission products has been achieved in nitrate media. From the results of partition experiments, attempts have been made to deduce the nature of the extracted species.

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Selective solvent extraction of chromium(VI) using 2-hexylpyridine

Separation from uranium, thorium, fission products and first transition series elements

Journal of Radioanalytical and Nuclear Chemistry
Authors:
M. Iqbal
and
M. Ejaz

Abstract  

The extraction behaviour of trace and macroamounts of chromium(VI) from different mineral acid solutions by 2-hexylpyridine in chloroform has been investigated. In the chloride system, the extracted species is apparently (HPyH+)2 (Cr2O7)2− or HPy+(HCrO 4 ) for macro and trace amounts of chromium(VI), respectively. Among the common anions chloride and sulphate have little effect on extraction up to 1M concentration, while in the case of nitrate there is a continuous decrease in the extraction with the increase of salt concentration in the aqueous phase. The effect of ascorbate, acetate, citrate, oxalate, thiosulphate, thiocyanate ions on the extraction from 1M HCl was also examined. Separation factors of several elements relative to chromium(VI) have been described and the separation of chromium(IV) from a large number of elements has been achieved.

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Abstract  

The extraction of chromium(VI) from aqueous hydrochloric, nitric and sulfuric acid solutions by diphenyl-2-pyridylmethane(DPPM) dissolved in chloroform has been studied. Chromium(VI) is quantitatively extracted from hydrochloric acid solutions in the range 0.1–1M. With increasing acid concentration, the extraction of chromium diminishes and in concentrated acid solutions practically all the chromium remains in the aqueous phase. The quantitative back-extraction of chromium from the organic phase is possible with HCl or HNO3 at concentrations higher than 5M through the use of reducing agents. The composition of the extracted chromium(VI) species was studied in solution. The complexes (DPPMH)+HCrO 4 and (DPPMH)2Cr2O 7 are extracted for tracer and macro amounts of chromium(VI) respectively. The data have been utilized for the separation of chromium(VI) from base metal ions.

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Abstract  

Enrichment of51Cr has been made by recoil enrichment using potassium chromate as the target material. Irradiation of four days at a neutron flux of 2·1013n·cm−2·sec−1 in the core of PARR, followed by a chemical separation using a new liquid-anion exchanger, diphenyl-2pyridylmethane (0.1M in chloroform) gives a product of high specific activity (>30 Ci per gram), suitable for medical diagnostic applications.

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Abstract  

A very rapid method for the separation of molybdenum(VI) from neutron irradiated uranium and its fission products is described. The procedure is based on the selective extraction of molybdenum(VI) by a 0.1M solution of 2-hexylpyridine in benzene from 4M HCl+0.04M KSCN. Decontamination factors were estimated to be >104 for the radionuclides of niobium, zirconium, ruthenium, lanthanum, cerium, promethium, yttrium, strontium and barium.

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