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%.     

Radiochemical characterization and decontamination of rare-earth-element concentrate recovered from uranium leach liquors

Journal of Radioanalytical and Nuclear Chemistry - The paper deals with two rare earth elements (REE) concentrates recovered from uranium leach liquors after sorption separation of uranium....     

Determination of gold in leach liquors by anodic stripping voltammetry in non-aqueous medium

The anodic stripping voltammetry of gold in butyl acetate/methanol (2 + 1) mixture is reported. The tetrachloroaurate(III) complex is extracted into butyl acetate, lithium perchlorate in methanol is added, and gold is deposited on a glassy carbon rotating disk cathode at ?0.6 V vs. SCE. The deposited gold is stripped in the same medium at a scan rate of 50 mV s^?1. The method is suitable for the determination of gold (0.1–1 mg l^?1) in chloride leach liquors.     

Heterometric micro-determination of uranium (vi) by precipitation as phosphate

A method is presented for the heterometric détermination of uranium (VI) by titration with a solution of Na₂HPO₄. 1–8 mg uranium in 10 ml solution can be determined with an accuracy of 0.01 mg in about. 15 minutes. The influence of various nitrogen compounds and different working conditions were studied.     

Separation of uranium and thorium using tris(2-ethylhexyl) phosphate as extractant

The distribution behavior of uranium and thorium has been investigated in a biphasic system of different aqueous nitric acid concentrations and a solution of tris(2-ethylhexyl) phosphate (TEHP) inn-dodecane at 25°C. The effect of different uranium and thorium concentrations in the aqueous phase on the extraction of these metal ions is evaluated. These results indicate that TEHP is a better choice than tri-n-butyl phosphate (TBP) for the separation of²³³U from the irradiated thorium matrix.     

Quantum mechanical calculation of aqueuous uranium complexes: carbonate, phosphate, organic and biomolecular species

Background  

Quantum mechanical calculations were performed on a variety of uranium species representing U(VI), U(V), U(IV), U-carbonates, U-phosphates, U-oxalates, U-catecholates, U-phosphodiesters, U-phosphorylated N-acetyl-glucosamine (NAG), and U-2-Keto-3-doxyoctanoate (KDO) with explicit solvation by H₂O molecules. These models represent major U species in natural waters and complexes on bacterial surfaces. The model results are compared to observed EXAFS, IR, Raman and NMR spectra.     

Highly efficient epoxidation method of olefins with hydrogen peroxide as terminal oxidant, bicarbonate as a co-catalyst and oxodiperoxo molybdenum(VI) complex as catalyst

A combination of the newly synthesized and structurally characterized compound, [MoO(O2)2(saloxH)](saloxH2= salicylaldoxime) as catalyst, H2O2 as terminal oxidant and NaHCO3 as co-catalyst when stirred in CH3CN (10 cm3) at room temperature (rt) shows a very pronounced efficiency epoxidation of olefinic compounds, the method being green and economical.     

Efficient electrosorption of uranium(VI) by B,N, and P co-doped porous carbon materials containing phosphate functional groups

Journal of Solid State Electrochemistry - In this paper, polyphosphazene was synthesized as precursors using benzene-1,4-diboronic acid and hexachlorocyclotriphosphazene (HCCP) by a simple one-step...     

Separation,purification and recovery of thorium from monazite leach liquors by counter-current extraction process

Journal of Radioanalytical and Nuclear Chemistry - Separation and purification of thorium from monazite leach liquors was investigated by counter current extraction process. The Primene JM-T...     

Annealing of radiomanganese in KMnO4 and in mixed crystals of KMnO4 with KClO4, KReO4 and KBF4

The influence of recoil energy, ionizing radiation and crystal composition, on the retention and on the thermal annealing of radiomanganese in KMnO₄ is studied. It is reported, that the recoil energy is of no great influence. In pure KMnO₄ two annealing processes can be distinguished, one with a relatively low energy of activation leading to MnO₄⁻ as a result of oxygen transfer, and one with a higher energy of activation comprizing the reaction of recoil manganese with its former oxygen ligands. The second process can be suppressed by ionizing radiation and by fast neutron irradiation. The increase of the retention in mixed crystals with KClO₄ and KReO₄ is tentatively ascribed to the tendency to form species which have structures which are as similar as possible to that of the host matrix.     

Cobalt(III) carbonate and bicarbonate chelate complexes of tripodal tetraamine ligands containing pyridyl donors: the steric basis for the stability of chelated bicarbonate complexes

The synthesis and characterization (X-ray crystallography, UV/vis spectroscopy, electrochemistry, ESI-MS, and (1)H, (13)C, and (59)Co NMR) of the complexes [Co(L)(O(2)CO)]ClO(4)xH(2)O (L = tpa (tpa = tris(2-pyridylmethyl)amine) (x = 1), pmea (pmea = bis((2-pyridyl)methyl)-2-((2-pyridyl)ethyl)amine) (x = 0), pmap (pmap = bis(2-(2-pyridyl)ethyl)(2-pyridylmethyl)amine) (x = 0), tepa (tepa = tris(2-(2-pyridyl)ethyl)amine) (x = 0)) which contain tripodal tetradentate pyridyl ligands and chelated carbonate ligands are reported. The complexes display different colors in both the solid state and solution, which can be rationalized in terms of the different ligand fields exerted by the tripodal ligands. Electrochemical data show that [Co(tepa)(O(2)CO)](+) is the easiest of the four complexes to reduce, and the variation in E(red.) values across the series of complexes can also be explained in terms of the different ligand fields exerted by the tripodal ligands, as can the (59)Co NMR data which show a chemical shift range of over 2000 ppm for the four complexes. [Co(pmea)(O(2)CO)](+) is fluxional in aqueous solution, and VT NMR spectroscopy ((1)H and (13)C) in DMF-d(7) (DMF = dimethylformamide) over the temperature range -25.0 to 75.0 degrees C are consistent with inversion of the unique six-membered chelate ring. This process shows a substantial activation barrier (DeltaG(#) = 58 kJ mol(-1)). The crystal structures of [Co(tpa)(O(2)CO)]ClO(4)xH(2)O, [Co(pmea)(O(2)CO)]ClO(4).3H(2)O, [Co(pmap)(O(2)CO)]ClO(4), and [Co(tepa)(O(2)CO)]ClO(4) are reported, and the complexes containing the asymmetric tripodal ligands pmea and pmap both crystallize as the 6-isomer. The carbonate complexes all show remarkable stability in 6 M HCl solution, with [Co(pmap)(O(2)CO)](+) showing essentially no change in its UV/vis spectrum over 4 h in this medium. The chelated bicarbonate complexes [Co(pmea)(O(2)COH)]ZnCl(4), [Co(pmap)(O(2)COH)][Co(pmap)(O(2)CO)](ClO(4))(3), [Co(pmap)(O(2)COH)]ZnCl(4)xH(2)O, and [Co(pmap(O(2)COH)]ZnBr(4)x2H(2)O can be isolated from acidic aqueous solution, and the crystal structure of [Co(pmap)(O(2)COH)]ZnCl(4)x3H(2)O is reported. The stability of the carbonate complexes in acid is explained by analysis of the crystallographic data for these, and other slow to hydrolyze chelated carbonate complexes, which show that the endo (coordinated) oxygen atoms are significantly hindered by atoms on the ancillary ligands, in contrast to complexes such as [Co(L)(O(2)CO)](+) (L = (NH(3))(4), (en)(2), tren, and nta), which undergo rapid acid hydrolysis and which show no such steric hindrance.     

KMnO4-NaIO4对香紫苏醇的氧化

研究了在相转移催化或非相转移剂催化或硅胶支持下KMnO4-NaIO4对香紫苏醇的氧化。在3种不同条件下均得到成分单一的氧化产物香紫苏醚,收率分别为47%,21%和59%。     

Determination of uranium(VI) in natural waters after preconcentration on adsorbent containing m-aminophenol fragments

Sorption and complexing properties of a modified adsorbent based on a maleic anhydride-styrene copolymer towards uranium(VI) are studied and the main quantitative characteristics of the metal ion sorption are determined. An adsorbent containing m-aminophenol fragments is proposed for the selective sorption of uranium(VI) from solutions. The optimal sorption conditions have been found. The recovery of uranium(VI) under the optimal conditions exceeds 95%. A procedure of the sorption photometric determination of uranium(VI) in sea water is developed.     

Determination of uranium and radium in phosphate rock and technical phosphoric acid

Summary Uranium in phosphate rock can be determined radiometrically using gamma-counting and spectrophotometrically using arsenazo I. In the latter case the rock is dissolved in HNO₃, then uranium is extracted with tributyl phosphate, stripped with hot water and determined. For the determination of uranium in technical phosphoric acid, the fluorosilicate ion present as impurity must first be precipitated, the uranium separated on Amberlite IRA-400 in the sulfate form, then determined in the eluate spectrophotometrically by arsenazo I. Radium can be determined in leach solutions by the emanation method.

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Bestimmung von Uran und Radium in Phosphatgestein und technischer Phosphorsäure

Zusammenfassung Uran kann in Phosphatgestein radiometrisch mit -Zählung und spektralphotometrisch mit Arsenazo I bestimmt werden. Zur spektralphotometrischen Bestimmung wird die Probe in Salpetersäure gelöst, dann das Uran mit Tributylphosphat extrahiert, in heißes Wasser überführt und bestimmt. Zur Uranbestimmung in technischer Phosphorsäure muß zuerst das als Verunreinigung vorhandene Fluorosilicat gefällt und dann das Uran mit Hilfe von Amberlit IRA-400 in der Sulfatform abgetrennt werden, bevor es im Eluat mit Arsenazo I bestimmt werden kann. Radium kann in Auslaugungslösungen mit Hilfe der Emanationsmethode bestimmt werden.

     

Sulphate analysis in uranium leach iron(III) chloride solutions by inductively coupled Argon Plasma Spectrometry

Inductively coupled Argon Plasma Spectrometry is used for the indirect determination of sulphate in iron(III) chloride leach solution of Elliot Lake uranium ores via addition of a known amount of barium ions and analyzing for excess of barium. The ore contains approximately 7 wt% pyrite, FeS(2) as the major mineral which oxidizes to generate sulphate during leaching with fe(III). The effects of pH, the concentrations of Fe(III) and chloride ions and for presence of ethanol in the test samples on the accuracy of analysis are studied. It is found that unlike the Rhodizonate method, removal of iron(III) from or addition of ethanol to the test sample prior to analysis are not required. Linear calibration curves are obtained.     

Determination of uranium(VI) in monazite sand

The design and characterization of an argon segmented-solid phase extraction system is described. A 200 ul volume micro-column has been constructed for the preconcentration of rare earth elements (REEs) from salt matrices containing uranium. An inductively coupled plasma atomic emission spectrometer has been utilized for simultaneous detection of Sr, Y and the REEs (namely Ce, Eu, La, Nd, Pr, Sm) at levels ranging from 5- to 2000 ppm in LiC1/KCl samples containing U. Preconcentration factors of 100 fold have been demonstrated. The precision, linear dynamic range and column performance of the system will be presented.     

Synergistic extraction of uranium(VI) with tri-n-butyl phosphate and i-butyldodecylsulfoxide

Summary The synergistic extraction of uranium(VI) from aqueous nitric acid solution with a mixture of tri-n-butyl phosphate (TBP) and i-butyldodecylsulfoxide (BDSO) in toluene was investigated. The effects of the concentrations of extractant, nitric acid, sodium nitrate and sodium oxalate on the distribution ratios of uranium(VI) have been studied. The values of enthalpy change for the extraction reactions with BDSO, TBP and a mixture of TBP and BDSO in toluene were -23.2±0.8 kJ/mol, -29.2±1.4 kJ/mol and -30.6±0.6 kJ/mol, respectively. It has been found that the maximum synergistic extraction effect occurs when the molar ratio of TBP to BDSO is close to 1. The composition of the complex of the synergistic extraction is UO₂(NO₃)₂ ^. BDSO ^. TBP.     

Polarographic determination of uranium(VI) in aqueous tri-n-butyl phosphate solutions

The effect of TBP as well as the organic diluents on the polarographic wave of U(VI) reduction has been investigated in sulphuric and perchloric acids. It was found that the presence of TBP traces in the solution to be analyzed induced another wave which was more prominent in sulphuric acid solutions. This can be eliminated by boiling the solutions for about 5 min before their analysis for uranium. The effect of supporting electrolyte on the polarographic reduction of U(VI) was also studied and the use of 6N HClO₄ was recommended.