Ion exchange separation of Eu(III), Th(IV), U(VI) and Pu(IV) ions on Amberlyst A-15 in non-aqueous solutions

Distribution ratios of europium(III), thorium(IV), uranium(VI) and plutonium(IV) ions on Amberlyst A-15, a macroreticular polystyrene sulfonate resin, after extraction in HTTA-TBP-Shell Sol-T and HTTA-TOPO-benzene solutions have been determined as a function of the aqueous acidity. The affinity orders were EuPu>Th>U and Eu>Th>Pu>U in the former and the latter solutions, respectively. Separation factors were computed from the observed K_d values. A procedure for the separation of a mixture of Eu(III), Th(IV), and U(VI) ions in HTTA-TOPO-benzene solution in an ion-exchange column is described.     

Flow-injection spectrophotometric determination of molybdenum and vanadium with carminic acid in the presence of cetyltrimethylammonium bromide

The color-forming reactions of molybdenum(VI) and vanadium(IV) with carminic acid (CA) in the presence of cetyltrimethylammonium bromide (CTAB) were used in the flow-injection determination of these metals. The micellar medium enhances the spectrophotometric features of the Mo(VI)-CA and V(IV)-CA binary complexes, and the higher solubility of these complexes when the CTAB concentration is above critical micelle concentration permits the easy application of flow-injection systems. Under the optimum conditions, linear calibration graphs were obtained from 0.76 to 28.8 g/ml for molybdenum and from 0.30 to 9.1 g/ml for vanadium. The detection limits were 0.33 and 0.16 g/ml for molybdenum and vanadium, respectively. The selectivity of the method was investigated and the procedure was successfully applied to the determination of molybdenum in steels and pharmaceuticals and of vanadium in petroleum products.     

Uranium(VI) and Thorium(IV) Adsorption Studies on Chelating Resin Containing Pentaethylenehexamine as a Functional Group

A new chelating resin (glycidyl methacrylate/divinylbenzene/pentaethylenehexamine (GMA/DVB/PEHA)) for uranium(VI) and thorium(IV) has been developed by functionalizing GMA/DVB with PEHA. The adsorption of U(VI) and Th(IV) ions onto the functionalized GMA/DVB/PEHA were investigated as a function of pH value, contact time, and temperature using batch adsorption technique. The results showed that U(VI) and Th(IV) adsorption onto GMA/DVB/PEHA was strongly dependent on pH. Kinetic studies revealed that the adsorption process achieved equilibrium within 15 and 90 minutes for Th(IV) and U(VI), respectively, and followed a pseudo-second-order rate equation. The isothermal data correlated with the Langmuir model better than the Freundlich model. Thermodynamic data indicated the spontaneous and endothermic nature of the process. The maximum adsorption capacity of U(VI) and Th(IV) were found to be 114 and 78 mg/g, respectively. Quantitative recovery of uranium and thorium were achieved by desorbing the loaded GMA/DVB/PEHA with 0.5 M HNO₃      

Simultaneous determination of uranium(IV) and iron(II) with a stopped-flow inductive kinetic spectrophotometric method

A kinetic method for simultaneous determination of multielements is proposed, and a procedure for simultaneous determination of uranium(VI) and iron(II) is established based on their inductive effect on the chromium(VI)-iodide redox reaction in weak acidic medium. The reaction was monitored with the stopped-flow spectrophotometric technique by using I ₃ ^– -starch complex as indicator. The calibration graphs are linear for 0–3.6 g.cm^–3 U(IV), and 0–2.5 g.cm^–3 Fe(II), respectively. Most foreign ions, except for V(IV), Sb(III), do not interfere with the determination.     

Actinide and lanthanide extraction from nitric acid solutions by flotation

Flotation of thorium, plutonium (IV), uranium(VI) and gadolinium from aqueous nitric acid solutions (HNO₃ concentration from 0.01 to 5.0M) was investigated using lauryl phosphoric acid (LPA) as a SAS-collector. It is established that the extent of removal of the metal ions increases with the amount of LPA introduced, regardless of the solution acidity. At a fixed mole LPA to metal ratio the extent of uranium(VI) and gadolinium removal is reduced with increasing acidity, while in case of plutonium(IV) and thorium this parameter remains constant. It is shown that in principle 100% extraction of plutonium(IV) and thorium by flotation is possible regardless of the acidity of aqueous solutions. Ca(NO₃)₂ added to the system in the amount of 0.5M does not significantly affect the flotation extraction of thorium.     

Liquid-liquid extraction and separation studies of uranium(vi)

Summary Separation of uranium(VI) from iron(III), molybdenum(VI), vanadium (V), bismuth(III), zirconium(IV) and thorium(IV) is achieved by liquid-liquid extraction with 4-methyl-3-pentene-2-one (mesityl oxide; MeO) from sodium salicylate media (0.1M, pH 6.0). The extracted species is UO₂(HO·C₆H₄COO)₂·2MeO. A procedure for separating 50g of uranium from mg amounts of the other metals is described.

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Flüssig-flüssig-Extraktion und Trennung von Uran(VI)

Zusammenfassung Die Trennung des U(VI) von Fe(III), Mo(VI), V(V), Bi(III), Zr(IV) und Th(IV) läßt sich durch Flüssig-flüssig-Extraktion mit 4-Methyl-3-penten-2-on] (Mesityloxid, MeO) aus 0,1M Natriumsalicylat bei pH 6,0 durchführen. Die extrahierte Verbindung ist UO₂(HO·C₆H₄COO)2·2MeO. Ein Verfahren zur Abtrennung von 50g Uran von Milligrammengen der anderen Metalle wurde beschrieben.

     

A new potentiometric determination of hydrazine in the presence of uranium(IV)

The present method describes the determination of hydrazine by making use of potentiometric titration technique. The underlying principle is back titration of uncreacted excess cerium remaining after the complete oxidation of hydrazine. Standardized ferrous ammonium sulfate was used for titration. This method was applied to real samples generated from a nuclear reprocessing plant wherein control of hydrazine is of paramount importance. The interference of U(IV), Cr(III), U(VI), nitrite, and chloride was studied and of all these ions the way to eliminate the interference of U(IV) was only attempted. The relative standard deviations (RSD) for synthetic as well as real samples were determined. The method gives RSD of less than 1% in the range of 1 mg to 20 mg of hydrazine. The error in the range 3 mg to 17 mg was found to be less than 1%.Plant operation section, Reprocessing Group.     

Rapid spectrophotometric determination of thorium(IV) with 1-(2′-thiazolylazo)-2-naphthol

Thorium(IV) reacts with 1-(2-thiazolylazo)-2-naphthol (TAN) in the presence of antipyrine to form a sparingly soluble red-coloured chelate, soluble in 36% methanol (v/v). Complexation takes place instantaneously at pH 2.4–2.8, maintained by glycine buffer. Antipyrine is found to enhance sensitivity of the complex, which is stable for 19 hours. The 12 complex exhibits maximum absorbance at 555 nm, obyes Beer's law in the concentration range from 0.32 to 6.56 g of thorium(IV) per ml, has a molar absorptivity of 3.14·10⁴ dm³/mol^–1·cm^–1 and a Sandel sensitivity of 7.4 ng·cm^–2. The formation constant (log K) is found to be 8.62 and 8.45. Interference of 57 anions and cations in the determination of thorium(IV) has been studied. From ten repeated determinations, the coefficient of variation was found to be ±0.98%. The method was successfully applied for determination of thorium content in a sample of monazite.     

Simultaneous determination of uranium(VI) and thorium(IV) ions with carminic acid by the partial least squares (PLS-1 and PLS-2) methods

Two multivariate calibration methods, partial least squares types 1 and 2 (PLS-1 and PLS-2) have been applied to the simultaneous determination of U(VI) and Th(IV) ions as complexes with carminic acid by visible absorption spectrophotometry. The results obtained by application of different chemometric approaches are discussed. No significant advantages were found between the methods. The proposed methods were applied satisfactorily to the determination of these ions in synthetic solutions simulating sulfuric acid leach solutions obtained from uranium-thorium ores.     

A sensitive spectrophotometric method for the determination of trace amounts of uranium(VI) using 2-hydroxy-1-naphthaldehyde isonicotinoyl hydrazone

The reaction between uranium(VI) and 2-hydroxy-1-naphthaldehyde isonicotinoyl hydrazone (2HNAINH) has been investigated in HCl-sodium acetate buffers and a highly sensitive and simple procedure for the determination of uranium(VI) is suggested. The orange red colored complex showed maximum absorption at 430 nm in buffer solutions of pH 3. Beer's law is obeyed in the range of 0.2 to 33 g ml^–1. The molar absorptivity and Sandell's sensitivity are found to be 9.6×10³ mol·l^–1 and 0.025 g cm^–2, respectively. The composition of the complex between metal and reagent is found to be 11. The effect of diverse ions is also studied and the method is successfully applied for the determination of uranium in synthetic mixtures.     

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.

     

Coulometric determination of uranium in presence of iron/plutonium using a platinum working electrode

A controlled potential coulometric method for the determination of uranium in the presence of iron or plutonium using a platinum working electrode has been developed. The method consists of reduction of uranium in 8M H₂SO₄ by Ti(III) followed by destruction of excess Ti(III) and selective oxidation of Fe(II) or Pu(III) to Fe(III) or Pu(IV), respectively, by sodium nitrite. The U(IV) is subsequently determined by electrolytic oxidation at Pt electrode using Fe(III) as an intermediate. The method was employed for the determination of uranium in synthetic mixtures of U+Fe and U+Pu containing varying ratios of U/Fe or U/Pu. The precision obtained for uranium results was ±0.25%.     

N,N,N′,N′-tetrabutylsuccinylamide as a new extractant in n-dodecane for extraction of uranium(VI) and thorium(IV) ions

N,N,N,N-tetrabutylsuccinylamide (TBSA) was synthesized, characterised and used for the extraction of U(VI) and Th(IV) from nitric acid solutions into n-dodecane. Extraction distribution coefficients of U(VI) and Th(IV) as a function of aqueous nitric acid concentration, extractant concentration and temperature have been measured and found that n-dodecane as diluent was superior to 50% 1,2,4-trimethyl benzene (TMB) and 50% kerosene, (OK) system for extraction of U(VI) and Th(IV). The compositions of extracted species, equilibrium constants and enthalpies of extraction reactions have also been calculated. The formation of the 121 complex of uranyl(II) ion or the 141 complex of thorium(IV) ion, nitrate ion and TBSA and extracted species was further confirmed by the IR spectra of saturated extract of U(IV) and Th(IV).     

A new procedure for the spectrophotometric determination of uranium(VI) in the presence of a large excess of thorium(IV).

Spectrophotometric determination of microgram amounts of U(VI) with 2-(5-Bromo-2-Pyridylazo)-5-diethylaminophenol (Br-PADAP), originally developed by Johnson and Florence has been modified to enable the determination of U(VI) in the presence of a large excess of Th(IV). The effects of thorium, tri-n-butyl phosphate (TBP) and ethanol on the estimation of uranium have been studied in detail and are presented in this paper. This modified method can be applied for the analysis of U(VI) both in aqueous and organic samples containing a large excess of Th(IV) (Th:U = 10000:1).     

Preconcentration and determination of ultra-trace amounts of U(VI) and Th(IV) using titan yellow-impregnated Amberlite XAD-7 resin

A simple and sensitive method for the determination of ultra trace amounts of U(VI) and Th(IV) ions by spectrophotometric method after solid-phase extraction on a new extractant-impregnated resin (EIR) has been reported. The new EIR was synthesised by impregnating a weakly polar polymeric adsorbent, Amberlite XAD-7, with titan yellow (TY) as extractant. The analytical method is based on the simultaneous adsorption of analyte ions in a mini-column packed with TY/XAD-7 and performing sequential elution with 0.5% (w/v) Na₂CO₃ for uranium and 2.0 M HCl for thorium. The influences of the analytical parameters including pH, salting out agent and sample volume were investigated. The interference effects of foreign ions on the retention of the analyte ions were also explored. The limits of detection for U(VI) and Th(IV) were as low as 50 and 25 ng L^?1, respectively. Relative standard deviations (n = 7) for U(VI) and Th(IV) were 3.1% and 2.9%, respectively. The method was successfully applied to the determination of ultra trace amounts of U(VI) and Th(IV) in different real matrices including industrial wastewater samples and environmental waters. The proposed method was validated using three certified reference materials and the results were in good agreement with the certified values.     

Extraction and spectrophotometric determination of uranium(VI) withN-phenylcinnamohydroxamic acid

Uranium(VI) reacts withN-phenylcinnamohydroxamic acid to form an orange-yellow complex in the pH range 5.5–8.5. The orange-yellow complex, having the composition of 12 (metal:ligand), is quantitatively extractable into ethyl acetate. The spectrum of the complex exhibits a maximum absorption at 400 nm with a molar absorptivity of 6500 M^–1·cm^–1. The coloured system obeys Beer's law in the concentration range 2–40g·ml^–1 of uranium(VI). The photometric sensitivity of the colour reaction is 0.037 g·cm^–2 of uranium(VI). Most of the common ions do not interfere and the method has been found to be simple, precise, and free from the rigid control of experimental conditions. The method has been applied to the determination of uranium in synthetic matrices and potable water.     

Nuclear interferences of uranium and thorium in a reactor neutron activation analysis determination of cerium using the radionuclides141Ce and143Ce

The interference contributions of uranium and thorium to the determination of cerium based on radionuclides¹⁴¹Ce and¹⁴³Ce produced by irradiation in a reactor core was determined. The values of the interference contributions for¹⁴¹Ce were 0.28±0.01 g Ce/g U and /2.01±0.05/x10^–3 g Ce/g Th, and for¹⁴³Ce 1.33±0.03 g Ce/g U and /9.0±0.2/x10^–3 g Ce/g Th.     

A sensitive spectrophotometric method for the determination of trace amounts of uranium (VI) using o-hydroxypropiophenone isonicotinoyl hydrazone

The reaction between uranium (VI) and o-hydroxypropiophenone isonicotinoyl hydrazone (OHPINH) has been investigated in HCl-sodium acetate buffers and a highly sensitive and simple procedure for the determination of uranium (VI) is suggested. The yellow colored complex showed maximum absorption at 380 nm in buffer solutions of pH 3. Beer's law is obeyed in the range of 0.47–17 g ml^–1. The molar absorptivity and Sandell sensitivity are found to be 1.15×10⁴ dm³ mol^–1 cm^–1 and 0.02 g cm^–2, respectively. The composition of the complex is found to be 11 between metal and reagent.     

Speciation studies by capillary electrophoresis- Simultaneous determination of chromium(III) and chromium(VI)

A method for the simultaneous determination of chromium(III) and chromium(VI) by capillary electrophoresis (CE) has been developed. The chromium(III) has been chelated with 1,2-cyclohexanediaminetetraacetic acid (CDTA) in order to impart a negative charge and similar mobility to both the chromium(III) and the chromium(VI) species. The effects of the amount of the reagent, pH and heating time required to complete the complexation have been studied. Factors affecting the CE behaviour such as the polarity of electrodes and the pH of electrophoretic buffer have been investigated. The separated species have been monitored by direct UV measurements at 214 nm. The detection limits achieved are 10 g/l for Cr(VI) and 5 g/l for Cr(III) and linear detector response is observed up to 100 mg/l. The procedure has been applied to the determination of both chromium species in industrial electroplating samples and its accuracy was checked by comparing the results (as total chromium) with those of atomic absorption spectrometry. No interference occurred from transition metal impurities under optimized separation conditions. The method is also shown to be feasible for determining Cr(III) as well as other metal ions capable to form complexes with CDTA (like iron(III), copper(II), zinc(II) and manganese(II)) in pharmaceutical preparations of essential trace elements.     

Improved spectrophotometric determination of uranium(VI) with 4-(2-pyridylazo)resorcinol in the presence of benzyldimethylstearyltrimethylammonium chloride

An improved spectrophotometric determination of uranium(VI) is proposed using 4-(2-pyridylazo)resorcinol(PAR) in the presence of benzyldimethylstearyltrimethylammonium chloride(BSTAC) as a cationic surfactant. The calibration graph is linear in the range of 0.3–60 g/10 ml uranium(VI), measuring the absorbance at 550 nm. The reproducibility for 19.0 g/10 ml uranium(VI) is 0.57%. The third-derivative method using the third-derivative distance (d³A/d³) among ₁ 530 nm, ₃ 594 nm and ₂ 565 nm was also investigated.