Cation-exchange behaviour of uranium(vi) on amberlite ir-120 : Separation from mixtures

Quantitative studies are reported on the cation-exchange behaviour of uranium(VI) at the milligram level with Amberlite IR-120. Hydrochloric, nitric, sulphuric, perchloric, acetic and citric acids were tested as cluants; 200–300 ml of 2 N hydrochloric, nitric or sulphuric acid suffice for quantitative elution of 17 mg of uranium(VI) from a 1.4 cm X 14 5 cm bed The efficiency of the elutmg agents is discussed in terms of their elution constants Uranium is separated from thorium by selective elution, from zirconium, cerium(III), copper and nickel by converting the latter into suitable anionic complexes and from phosphate just by passing the mixture through the cation exchanger.     

Solvent extraction of scandium from malonic acid with high molecular-weight amines

Scandium is quantitatively extracted with 4% Amberlite LA-1 or Amberlite LA-2 in xylene at pH 2.5-5.5 from 0.1M malonic acid. Scandium is stripped from the organic phase with 0.5M hydrochloric acid and determined spectrophotometrically at 525 nm, as its complex with Alizarin Red S. Primene JM-T, tri-iso-octylamine, tributylamine and tribenzylamine have also been studied as extractants, but found to be unsatisfactory for various reasons. Xylene, toluene, benzene, chloroform, carbon tetrachloride, hexane, cyclohexane and kerosene have been studied as diluents. Xylene is found to be the most efficient. Scandium can be separated from most metals by selective extraction, and from gallium, thallium(III), bismuth, antimony(III), chromium(III), copper(II), iron(III), uranium(VI), cerium, zirconium, indium, thorium and titanium by selective stripping, in some cases combined with use of suitable complexing media to retain the other metals in the organic phase.     

Reversed phase extraction chromatography of chromium with tributylphosphate on silica gel

Summary A silica-gel column impregnated with TBP will extract various metal ions from hydrochloric acid media of various concentrations. Chromium(VI) is readily separated in this way from many other metal ions by use of selective extraction and elution. Chromium(VI) is easily separable from chromium(III). Chromium(VI) is separable from binary mixtures with alkali and alkaline earths, scandium, yttrium, cerium, zirconium, thorium, vanadium, manganese, iron, cobalt, nickel, copper, zinc, aluminium, gallium, indium, germanium, tin, lead, antimony, bismuth and tellurium by selective sorption, and from multicomponent mixtures [e. g. with copper or cobalt, vanadium and thorium; titanium, vanadium(V) and uranium(VI); iron(III) and molybdenum(VI)] by selective sorption and elution. The method is applicable to analysis of alloys.

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Extraktionschromatographische Trennung von Chrom mit Tributylphosphat auf Silicagel

Zusammenfassung Mit einer Silicagel-Säule, die mit Tributylphosphat imprägniert wurde, lassen sich verschiedene Metallionen aus salzsaurem Medium verschiedener Konzentration extrahieren. Chrom(VI) ist auf diese Art gut von vielen anderen Metallionen durch selektive Extraktion und Elution zu trennen. Es ist auch von Chrom(III) leicht trennbar. Ebenso kann man Chrom(VI) aus binären Gemischen mit Alkalien, alkalischen Erden, Scandium, Yttrium, Cer, Zirkon, Thorium, Vanadin, Mangan, Eisen, Kobalt, Nickel, Kupfer, Zink, Aluminium, Gallium, Indium, Germanium, Zinn, Blei, Antimon, Wismut und Tellur durch selektive Sorption trennen. Aus Mehrfachgemischen, z. B. mit Kupfer oder Kobalt, Vanadin und Thorium; Titan, Vanadin(V) und Uran(VI); Eisen(III) und Molybdän(VI) ist es ebenfalls durch selektive Sorption und Elution trennbar. Das Verfahren eignet sich für die Analyse von Legierungen.

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Presented at the 8th International Microchemical Symposium, Graz, August 25–30, 1980.     

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.     

Extraction chromatographic separation of thorium (IV) with tri-n-octylphosphine oxide (TOPO)

Thorium was extracted from a mixture of nitric acid and NaNO₃ of 0.01M each at pH 2.2 on a column of silica gel coated with TOPO. Thorium was separated from alkalis, alkaline earths, chromium, iron, cobalt, nickel, zinc, cadmium, mercury, lead, trivalent rare earths, platinum group metals, chloride, phosphate and acetate in binary mixtures by selective extraction of thorium. Thorium was separated from cerium (IV), zirconium, uranium and molybdenum by selective elution of thorium with 0.01M H₂SO₄. The method was extended for the analysis of thorium in monozite ore.     

Extractive separation of Th(IV), U(VI), Ti(IV), La(III) and Fe(III) from Zarigan ore

In this study, the effects of various extraction parameters such as extractant types (Cyanex302, Cyanex272, TBP), acid type (nitric, sulfuric, hydrochloric) and their concentrations were studied on the thorium separation efficiency from uranium(VI), titanium(IV), lanthanum(III), iron(III) using Taguchi^??s method. Results showed that, all these variables had significant effects on the selective thorium separation. The optimum separations of thorium from uranium, titanium and iron were achieved by Cyanex302. The aqueous solutions of 0.01 and 1 M nitric acid were found as the best aqueous conditions for separating of thorium from titanium (or iron) and uranium, respectively. The combination of 0.01 M nitric acid and Cyanex272 were found that to be the optimum conditions for the selective separation of thorium from lanthanum. The results also showed that TBP could selectively extract all studied elements into organic phase leaving thorium behind in the aqueous phase. Detailed experiments showed that 0.5 M HNO₃ is the optimum acid concentration for separating of thorium from other elements with acidic extractants such as Cyanex272 and Cyanex302. The two-stage process containing TBP-Cyanex302 was proposed for separation thorium and uranium from Zarigan ore leachate.     

Study of scandium and thorium sorption from uranium leach liquors

Scandium and thorium sorption from simulated uranium leach liquors by phosphorous containing ion exchange resins was studied. Increase of thorium concentration resulted in a decrease of scandium sorption by 26–65%. Tulsion CH 93 resin was chosen for Sc separation from uranium leach liquors. It was shown that 180 g L^?1 Na₂CO₃ allowed for elution 94.1% of Sc and 98.9% of Th in dynamic conditions. Using (NH₄)₂SO₄ (50 g L^?1) + ACBM (180 g L^?1) mixture for primary Sc/Th separation at the resin/eluent ratio of 1:5 resulted in thorium desorption degree as high as 66–69%, whereas scandium loss did not exceed 10%.     

Separation of Thorium(IV) from Associated Elements Using Poly-(Dibenzo-18-Crown-6) and Column Chromatography from Picric Acid Medium

A simple column chromatographic method has been developed for the separation of thorium(IV) from associated elements using poly-(dibenzo-18-crown-6). The separations are carried out from picric acid medium. The adsorption of thorium(IV) was quantitative from 0.0005–0.05M picric acid. Amongst the various eluents tested, 2.0–8.0M HCl, HBr, 1.0–6.0M HClO₄ and 5.0M acetic acid were found to be particularly efficient for the quantitative elution of thorium(IV). The capacity of poly-(dibenzo-18-crown-6) for thorium(IV) was found to be 1.29±0.01 mmol/g of crown polymer. Thorium(IV) was separated from a number of cations in binary mixtures in which most of the cations showed a very high tolerance limit. It was possible to separate thorium(IV) from a number of cations such as lanthanum(III), yttrium(III), uranium(VI), beryllium(II) and barium(II) in multicomponent mixtures. The method was extended to the determination of thorium in monazite sand. It is possible to separate and determine 5 ppm of thorium(IV) by this method. The method is very simple, rapid, selective and has good reproducibility (approximately ±2%).     

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.     

Reversed phase extraction chromatographic separation of thorium with Amberlite LA-1 from malonate solutions

Thorium was extracted at pH 5.0 from 0.01 M malonic acid on a column of silica gel coated with Amberlite LA-1. Thorium was separated from alkali and alkaline earths, managenese, iron, cobalt, nickel, zinc, tin, in binary mixtures by taking advantage of the difference in the pH of formation of malonato complexes. Thorium was separated from zirconium, uranium, scandium, molybdenum, titanium, by exploiting the difference in the stability of malonato complexes. The method was extended for the analysis of thorium in monazite.     

Cation exchange studies of vanadium(V) on Dowex 50W-X8. Separation from mixtures

Summary The cation exchange behaviour of milligram amounts of vanadium on Dowex 50W-X8 has been studied using different eluants. Quantitative elution can be achieved by 200 ml of 0.5N hydrochloric acid, 1–2N sulphuric acid, 2–3N phosphoric acid or 0.5–1N ammonium chloride solution. The relative efficiency of eluants is discussed in terms of their elution constants and bed distribution coefficients. Vanadium has been separated from copper(II), iron(III), cobalt(II), nickel, zinc, zirconium (IV), aluminium, cerium(IV), uranium(VI), thorium(IV), manganese(II), titanium(IV), and from phosphate.

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Zusammenfassung Das Verhalten von Milligramm-Mengen Vanadium am Kationenaustauscher Dowex 50W-X8 wurde mit verschiedenen Eluierungsmitteln untersucht. Mit 200ml 0,5 n Salzsäure, 1–2 n Schwefelsäure, 2–3 n Phosphorsäure oder 0,5–1 n Ammoniumchloridlösung konnte das Vanadium quantitativ eluiert werden. Die Wirksamkeit dieser Eluierungslösungen wurde an Hand der Elutionskonstanten und der Verteilungskoeffizienten erörtert. Von folgenden Ionen konnte das Vanadium getrennt werden: Kupfer(II), Eisen(III), Kobalt(II), Nickel, Zink, Zirkonium(IV), Aluminium, Cer(IV), Uran(VI), Thorium(IV), Mangan(II), Titan(IV) und Phosphat.

     

Determination of uranium and thorium in solar salts by neutron activation analysis

Uranium and thorium contents of solar salts were measured by neutron activation analysis. In advance of neutron irradiation, U and Th were concentrated and separated from some interfering elements by neutralization in which they were precipitated with aluminium hydroxide from solutions obtained by dissolving the salts in water or dilute nitric acid solution. The uranium and thorium concentrations determined were from several hundred ppt to 10 ppb. It was strongly indicated that uranium tends to remain in the solution (brine from seawater) phase in the process of solar salt production while thorium tends to transfer to the solid (solar salt) phase.     

Synergistic extraction and separation studies of uranium(VI)

A method is described for the extractive separation and spectrophotometric determination of uranium(VI) from an aqueous solution of pH 5.0–7.0 using benzoylacetone (bzac) and pyridine (py) dissolved in toluene as extractants. The extracted species are UO₂(bzac(₂·2py. The method provides separation of uranium(VI) from lanthanum(III), samarium(III), neodymium(III), cerium(III) and thorium(IV). The method is precise, accurate, fast and selective.     

Spectrophotometric determination of trace uranium in geological samples by flow injection analysis with on-line levextrel resin separation and preconcentration

A flow-injection system with on-line separation and preconcentration is described for the spectrophotometric determination of trace uranium in geological samples. Uranium is selctively adsorbed from 0.7 mol l^?1 nitric acid on a microcolumn (40 mm long, 4.4 mm i.d.) containing levextrel CL-5209 resin (120–200 mesh) and separated from the sample matrix and most of the co-existing ions; 10-fold concentration is obtained. Eluted uranium is determined spectrophotometrically with arsenazo-III. The detection limit is μg l^?1 uranium and calibration is linear up to 0.3 mg l^?1 uranium With dual columns operated alternately for adsorption and elution, 30 samples can be analyzed per hour. Masking agents are added to eliminate interferences from thorium and iron. The method is sensitive and highly selective, easy to operate and suitable for routine analysis of geological samples for uranium.     

Neutron activation analysis for ultra low contents of uranium and thorium in aluminium and silica

Highly sensitive neutron activation analysis of uranium and thorium in high quality silica and aluminium has been investigated using the Japan Materials Testing Reactor (JMTR), having a thermal neutron flux higher than 10¹⁴ n/cm²/s. In order to determine ultra-low contents of uranium and thorium,²³⁹Np and²³³Pa as activation products were separated by using anion exchange and LaF₃ coprecipitation methods. As a result, a number of interfering radioactive isotopes containing double neutron capture product such as¹⁸³Ta were removed completely from the isolated²³⁹Np and²³³Pa fraction and the detection limits for uranium and thorium were found to be 2·10^–12 g and 4·10^–13 g, respectively.     

Anion-exchange separation of scandium from yttrium,lanthanum, cerium and other elements in malonic and ascorbic acid media

Summary The anion-exchange behaviour of scandium was studied in malonate and ascorbate media on Dowex 2×8 colums (1.4×18 cm). It forms anionic complexes with 8% malonic acid at pH 5.0 and 5% ascorbic acid at pH 6.5. Various eluants such as mineral acids and their corresponding salts were tested eluants and their efficiencies evaluated. Scandium was separated from alkali metals, alkaline earth metals Tl(I), Hg(II) and Fe(II). It was separated from Co, Ni, Pd, Mn, Cd and Zn by selective washing of the column and from other elements by selective elution in both systems. The separation of scandium from Y, La, Ce, Pr, Nd, Sm, Gd and Dy were a remarkable feature of the method.     

Determination of uranium and thorium in complex samples using chromatographic separation, ICP-MS and spectrophotometric detection

The paper describes a research of possible application of UTEVA and TRU resins and anion exchanger AMBERLITE CG-400 in nitrate form for the isolation of uranium and thorium from natural samples. The results of determination of distribution coefficient have shown that uranium and thorium bind on TRU and UTEVA resins from the solutions of nitric and hydrochloric acids, and binding strength increases proportionally to increase the concentration of acids. Uranium and thorium bind rather strongly to TRU resin from the nitric acid in concentration ranging from 0.5 to 5 mol L⁻¹, while large quantities of other ions present in the sample do not influence on the binding strength. Due to the difference in binding strength in HCl and HNO₃ respectively, uranium and thorium can be easily separated from each other on the columns filled with TRU resin. Furthermore, thorium binds to anion exchanger in nitrate form from alcohol solutions of nitric acid very strongly, while uranium does not, so they can be easily separated. Based on these results, we have created the procedures of preconcentration and separation of uranium and thorium from the soil, drinking water and seawater samples by using TRU and UTEVA resins and strong base anion exchangers in nitrate form. In one of the procedures, uranium and thorium bind directly from the samples of drinking water and seawater on the column filled with TRU resin from 0.5 mol L⁻¹ HNO₃ in a water sample. After binding, thorium is separated from uranium with 0.5 mol L⁻¹ HCl, and uranium is eluted with deionised water. By applying the described procedure, it is possible to achieve the concentration factor of over 1000 for the column filled with 1 g of resin and splashed with 2 L of the sample. Spectrophotometric determination with Arsenazo III, with this concentration factor results in detection limits below 1 μg L⁻¹ for uranium and thorium. In the second procedure, uranium and thorium are isolated from the soil samples with TRU resin, while they are separated from each other on the column filled with anion exchanger in alcohol solutions. Anion exchanger combined with alcohol solutions enables isolation of thorium from soil samples and its separation from a wide range of elements, as well as spectrophotometric determination, ICP-MS determination, and other determination techniques.     

O-carboxyphenyl azo chromotropic acid (sodium salt) as an analytical reagent

Summary 0-carboxyphenyl azo chromotropic acid (sodium salt), named as chromotrope 2 C, is used as a new colorimetric reagent for the determination of micro amounts of thorium and aluminium. The blue-violet and red-violet complexes show maximum absorption at 590 nm and the colour systems obey Beer's law from 0.1 to 8 ppm for thorium and 0.1 to 1ppm for aluminium. However, their optimum concentration ranges are from 1.6 to 8 ppm for thorium and 0.2 to 0.8 ppm for aluminium, where the percent relative errors per 1% absolute photometric error are, respectively, 3.06 and 2.94. The composition of the complexes, as elucidated by the continuous variation method, suggests a metal to reagent ratio of 23 for thorium and a ratio of 11 for aluminium. The instability constants for the complexes are of the order of 4.044×10^–10 and 1.006 × 10^–6 at 30°C.Part I, see Z. analyt. Chem. 174, 197 (1960)     

Preparation and properties of a new chelating resin containing 1-nitroso-2-naphthol as the functional group

A macroreticular polystyrene-based chelating ion-exchanger containing 1-nitroso-2-naphthol as the functional group has been synthesized. The exchange-capacity of the resin for a number of metal ions such as copper(II), iron(III), cobalt(II), nickel(II), palladium(II) and uranium(VI) as a function of pH has been determined. The sorption and elution characteristics for palladium(II) and uranium(VI) have been thoroughly examined with a view to utilizing the resin for separation and concentration of uranium and palladium. Uranium(VI) has been separated from a mixture of ten other metal ions by sorption on the chelating resin and selective elution with 0.5M sodium carbonate. Palladium(II) has been separated from various metal ions by selective sorption on the resin in 1M hydrochloric acid medium.     

Method of separating uranium from iron and thorium

Acid leaching of uranium deposits is not a selective process. Sulfuric acid solubilizes iron(III) and half or more of the thorium depending on the mineralog of this element. In uranium recovery by solvent extraction process, uranium is separated from iron by an organic phase consisting of 10 vol% tributylphosphate(TBP) in kerosine diluent. Provided that the aqueous phase is saturated with ammonium nitrate or made 4–5 M in nitric acid prior to extraction. Nitric acid or ammonium nitrate is added to the leach solution in order to obtain a uranyl nitrate product. Leach solutions containing thorium(IV) besides iron are treated in an analogous fashion. Uranium can be extracted away from thorium using 10 vol% TBP in kerosine diluent. The aqueous phase should be saturated with ammonium nitrate and the pH of the solution lowered to 0.5 with sufficient amount of sulfuric acid. In other words, the separation of uranium and thorium depends on the way the relative distributions of the two materials between aqueous solutions and TBP vary with sulfuric acid concentration. Thorium is later recovered from the waste leach liquor, after removal of sulfate ions. Uranium can be stripped from the organic phase by distilled water, and precipitated as ammonium diuranate.