Anion-exchange behavior of rare earths,thorium, protactinium and uranium in thiocyanate-chloride media

The anion exchange of rare earths(III), thorium(IV), protactinium(V) and uranium (VI) from thiocyanate-chloride media was investigated. The equilibrium, distribution study showed that the rare earths(III) and yttrium(III) were not significantly adsorbed on a basic anion-exchangc resin, while thorium(IV), protactinium(V) and uranium(VI) were strongly adsorbed. Adsorption from the thiocyanate-chloride solutions is in the order, U(Vl) > Pa(V) > Th(IV). The separation of rare earths(III) or yttrium(III), thorium(IV), protactinium(V) and uranium(VI) was successfully accomplished by column elution in thiocyanate-chloride media. A rapid and effective ion-exchange method for separating protactinium-233 from irradiated thorium(IV) is also presented.     

A separation of protactinium from neutron-irradiated thorium

A convenient-method, based on liquid-liquid extraction with N-benzoyl-N-phenylhydroxylamine in chloroform, is given for the separation of protactinium-233 from neutron-irradiated thorium.     

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.     

Chromatographic separation of rare earths and uranium from thorium

Ohne Zusammenfassung     

Anion-exchange separation and spectrophotometric determination of thorium in geological samples

To determine thorium in geological samples it is first separated from all matrix elements by means of anion-exchange. After elution thorium is determined spectrophotometrically by using thoronol or arsenazo III. The suitability of the method for the determination of both trace and larger amounts of thorium was tested by analysing numerous geochemical standard samples with thorium contents in the range of 1-1000 ppm. In all cases very good agreement was obtained.     

Extraction behaviour of thorium,protactinium, uranium and neptunium from mixed mineral acid solutions by TLA

Studies on the extraction of thorium, protactinium, uranium and neptunium from H₂SO₄ solutions by TLA indicated that these elements have low distribution coefficients (<0.1) at high acid concentrations. Additions of HCl or HBr to H₂SO₄ solutions enhances appreciably the extraction of the mentioned elements. A systematic investigation on the effect of halide concentration and solvetn concentration helped in explaining the observed enhancement as well as identifying the extracted complexes.     

Trace/matrix separation of uranium and thorium from molybdenum and tungsten matrix. A batch method for ultratrace bulk analysis

Summary A combined analytical procedure for spectro-photometric determination of uranium and thorium traces in high-purity molybdenum and tungsten matrices using the ion-exchanger cellulose Hyphan (TM of Riedel de Haën AG, FRG) for preconcentration is described. Following their separation (batch mode) uranium and thorium are determined as arsenazo-III complexes. The limits of detection (3) are 3 ng g^–1 U and 20 ng g^–1 Th. The analytical procedures elaborated improve the detection limits for U and Th in molybdenum and tungsten matrices by four and three orders of magnitude, respectively, compared to their determination by ICP-OES or DCP-OES without matrix separation. Accordingly, the procedures are routinely applicable in an industrial laboratory. The capability of this batch method can be validated by measurements of ion beam ratio with the glow discharge mass spectrometer; comparable results are obtained.     

Anion-exchange separation of uranium (VI) from thorium,zirconium, titanium,lanthanides and other elements in malonic and ascorbic acid media

Summary The anion-exchange behaviour of uranium (VI) has been studied extensively in various mineral acid media [1], but similar studies with organic acid solutions are lacking. Although the negatively charged complex of uranium in acetic acid was studied [2, 3], very small amounts of uranium could be separated and phosphate interfered. Such studies were further extended to non-aqueous media [4]. The anionic ascorbate complex of uranium and thorium were separated by selective elution with 1 mol dm^–3 hydrochloric acid and 3 mol dm^–3 sulphuric acid [5–7] respectively. Some attempts were also made to study complexes of uranium in formic and propionic acid [1] and it was separated from copper and thorium in oxalate media [4]. However systematic studies in malonate and to some extent in ascorbate media are lacking. This paper presents such studies.     

Anion-exchange separation of beryllium, vanadium and other elements from large amounts of uranium

A method is described for the anion-exehange separation of small quantities of beryllium, vanadium, magnesium, calcium, aluminium, gallium and indium from gram-amounts of uranium. For this purpose, a medium consisting of 95 % methanol and 5% 5M nitric acid is passed through a resin bed of Dowex 1, X8. By subsequent washing of the resin with a methanol-nitric acid mixture of the same composition, these metal ions are preferentially eluted from the column, whereas uranium is still retained by the anion exchanger. In the eluates the elements are determined by means of spectrophotometric or titrimetric procedures.     

Extraction of protactinium(V) chloro complexes by tri-capryl amine and its separation from thorium(IV), uranium(VI) and rare earths

The distribution of Pa(V) between aqueous HCl solutions and organic phases of tricaprylamine has been described. The dependence of extraction on acidity, salting-agent and extractant concentration was investigated. The possible extraction mechanism is discussed in the light of results obtained. The separation of Pa(V) from Th(IV), U(VI) and rare earths, is also suggested.     

Ion-exchange separation of uranium,thorium and plutonium isotopes from environmental samples

Radioisotopes of uranium, thorium and plutonium in water, soil and fertilizer samples, have been chemically separated and determined by alpha-spectrometry method. Radiochemical procedure involving ion-exchange, enabled to determine these isotopes in very low concentrations (under 50 Bq/g).²³²U,²²⁹Th and²³⁸Pu were used as a tracers for radiochemical yield recoveries (up to 90%). Thin layer sources have been obtained by electrodeposition.     

Paper chromatographic separation of thorium, zirconium and uranium

Summary The possibility of paper chromatographic separation of a number of elements (Th, U, Zr, Fe, Mg, Ni, Co, Ce, La, Y, Sm, Gd) has been studied, employing solvent mixtures containing tri-n-butyl phosphate (TBP) as principal constituent. Various factors that influence the R_f values have been investigated. It has been made possible to separate only thorium and uranium from the other elements including the rare earths and also from one another. Only thorium and uranium move under the conditions studied, the others remain stationary on the starting line. The solvent mixture methylisobutyl ketone-isobutyl alcohol-TBP (503812) shaken with 4 M HNO₃ proved to be a good mobile solvent for the separation of thorium and uranium. Thorium has also been separated from monazite extract. A single chromatogenic spray (-SNADNS-6) has been used for the detection of all the elements. Thorium, uranium and zirconium have also been quantitatively estimated after chromatographic separation by EDTA titration using the same dye.

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Zusammenfassung Die Möglichkeit der papierchromatographischen Trennung verschiedener Elemente (Th, U, Zr, Fe, Mg, Ni, Co, Ce, La, Y, Sm, Gd) mit tributylphosphathaltigen Laufmitteln ist untersucht worden. Hierbei wurde die Beeinflussung der R_f-Werte durch verschiedene Faktoren geprüft und eine Möglichkeit zur Trennung von Thorium und Uran voneinander sowie von anderen Metallen gefunden. Als Laufmittel hat sich am besten das Gemisch Methylisobutylketon-Isobutanol-Tributylphosphat (503812), äquilibriert mit 4 n Salpetersäure, bewährt. Nur U und Th wandern, alle anderen Elemente bleiben auf der Startlinie. Thorium konnte auch aus Monazitextrakt abgetrennt werden. -SNADNS-6 dient als einziges Nachweisreagens für alle genannten Metalle und wird auch als Indicator benutzt bei der komplexometrischen Titration von Zr, Th und U im Anschluß an die papierchromatographische Abtrennung.

     

Anion exchange separation of uranium, thorium and bismuth

Summary A method for the anion exchange separation of uranium, thorium and bismuth is described, using the strongly basic anion exchanger Dowex 1 X8. These three elements are simultaneously adsorbed on the resin (nitrate form) from a solution consisting of 96% n propanol and 4% 5 n nitric acid. The separation of thorium and bismuth from uranium is effected by washing the column with a mixture consisting of 80% methanol and 20% 5n nitric acid (elution of uranium). To separate thorium from bismuth the resin is then treated with a solution consisting of 80% methanol and 20% 6n hydrochloric acid whereby the thorium is eluted. Finally the bismuth is removed by washing the column with 1 n nitric acid. The experimental conditions for this separation scheme have been selected after the determination of the distribution coefficients of uranium, thorium, and bismuth in different mixtures of aliphatic alcohols with nitric and hydrochloric acid.

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Zusammenfassung Zur Trennung von Uran, Thorium und Wismut wird der stark basische Anionenaustauscher Dowex 1X8 verwendet. Aus einem Lösungsmittelgemisch von 96% n-Propanol und 4% 5n Salpetersäure werden die drei Elemente zusammen an dem Austauscher (Nitratform) adsorbiert. Mit einer Mischung von 80% Methanol und 20% 5n Salpetersäure wird sodann das Uran eluiert. Thorium wird mit einem Gemisch von 80% Methanol und 20% 6n Salzsäure ausgewaschen und schließlich wird mit 1 n Salpetersäure das Wismut von der Säule entfernt. Die Verteilungskoeffizienten der drei Metalle wurden in verschiedenen Gemischen von aliphatischen Alkoholen und Salz- sowie Salpetersäure bestimmt.

     

Anion-exchange separation of cobalt from nickel

An anion-exchange method has been developed for the separation of cobalt from nickel, based on the observation that from a malonic acid solution containing sodium nitrite, cobalt is preferentially adsorbed by the exchanger but nickel passes through. The cobalt is eluted with 2M ammonium chloride in dilute ammonia solution. Prom an ammonium malonate solution containing chloride and nitrate, cobalt is quantitatively electro-deposited on a platinum cathode to give a bright, adherent deposit. Nickel is deposited from a solution of similar composition.     

Separation of thorium from uranium ore

Thorium-230 has many research applications, but there is not a commercial source of this isotope. However, since ²³⁰Th is part of the ²³⁸U decay chain, it can be separated from naturally occurring uranium. In this work, a novel procedure was developed to separate thorium from uranium ore, consisting of leaching, liquid–liquid extraction, precipitations and ion exchange chromatography. The final product was 91.32?±?0.77 mg of thorium with a purity of 99.5?±?1.2 wt%. Of that, 7.65?±?0.10 mg was ²³⁰Th and the remainder ²³²Th. The total yield of ²³⁰Th was 71.1?±?5.4%. Ways to improve the yield by further processing the back-extraction solution are suggested.

     

ICP-AES determination of silver after chemical separation from uranium matrix

The separation of silver from a uranium matrix has been carried out using Cyanex-471X (triisobutylphosphine sulphide) in xylene. The effects of various parameters such as the Cyanex-471X concentration, the nitric acid molarity, the contact time and the nitrate ion concentration on the extraction of silver have been studied. The silver metal ion species extracted into the organic phase was found to be Ag(NO₃)·2S (where S is Cyanex-471X). The stripping of silver into an aqueous medium was carried out with 5% NaHSO₃, followed by its determination using ICP-AES.     

Radiochemical separation of thorium acetylacetonate from other thorium species

A solvent extraction technique to separate different chemical species of thorium is presented. The products formed by the chemical effects of the /n,/ reaction on the Th/acac/₄ were separated by this method and the retention value was measured.     

Anion-exchange system in magnesium nitrate media. Application to chemical analysis of manganese nodules for thorium and uranium

Summary The adsorption behaviour of 26 metal ions on the strongly basic anion-exchange resin Bio Rad AG-1, X-8 has been examined in magnesium nitrate media. The salt concentration range from 0.50-3.0 M is covered in the presence of 0.1 M free nitric acid. The distribution coefficients of bismuth(III), thorium(IV) and uranium(VI) rise to the order of 1,000 in media of 0.1 M nitric acid with high salt strength, while most other elements are only weakly adsorbed as is also the case in pure nitric acid media. The system allows thorium(IV) and uranium(VI) to be concentrated simultaneously from 2.5 M nitrate media, so that it can be applied successfully to the determination of thorium and uranium in manganese nodules with consecutive Chromatographic elution from a single small resin column. The subsequent determination is carried out spectrophotometrically with Arsenazo III.

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Anionenaustausch in Magnesiumnitratlösung. Anwendung zur Thorium- und Uranbestimmung in Manganknollen

Zusammenfassung Das Adsorptionsverhalten von 26 Metallionen wurde aus Magnesiumnitratlösung an dem stark basischen Anionenaustauscher Bio-Rad AG-1, X-8, untersucht. Die Salzkonzentration reichte von 0,5-3,0 M bei Gegenwart von 0,1 M freier Salpetersäure. Die Verteilungskoeffizienten von Bismut(III), Thorium(IV) und Uran(VI) reichen bei hoher Salzkonzentration bis zur Größenordnung von 1000, wogegen die meisten anderen Elemente nur schwach adsorbiert werden, was auch in reiner salpetersaurer Lösung der Fall ist. Dadurch können Th(IV) und U(VI) gleichzeitig aus 2,5 M Nitratlösung angereichert und mit gutem Erfolg in Manganknollen bestimmt werden, wobei nur eine einzige Elution von einer kleinen Harzsäule erforderlich ist. Die anschließende Bestimmung erfolgt spektralphotometrisch mit Arsenazo III.