Thin-Layer Chromatography Method for the Investigations of Re(VII), Mo(VI)

Abstract

The benavicur of Re(VII), Mo(VI) and V(V) ions was studied chromatographically in aliphatic alcohol -HC1 systems on Al ₂O₃ as an adsorbent. Changes in the chromatographic process with the changes of the kind and composition of mobile phase were analysed.

It was also attempted to describe theoretically the results of chromatograpnic separation by using the thermodynamic theory of adsorption from multicomponent solutions.     

Radiochemical separation of rhenium(VII) from tungsten(VI)

The absorption of rhenium(VII) and tungsten(VI) ions on Al₂O₃ from HCl, HClO₄, HNO₃, H₂SO₄, H₃PO₄, NaOH, NH₄OH, NaCl, NaF, and Na-tartarate solutions by batch equilibration, as well as by passage through a chromatographic column, has been studied. The results show that rhenium(VII) can be effectively separated from tungsten(VI) using any of the acid or salt solutions investigated. The experimental data allowed to develop a simple procedure for the radiochemical separation of rhenium isotopes from an irradiated WO₃ sample.     

Uranium(VI) extraction by Winsor II microemulsion systems using trialkyl phosphine oxide

Summary The parameters affecting the formation of the microemulsion were investigated and the microemulsion region was determined. The extraction of uranium(VI) from HNO₃ solution into a water in oil microemulsion was studied. The effects of the concentration of extractant (TRPO), the volume ratio of oil to water and the acidity of outer water phase on the extraction equilibrium of uranium(VI) are discussed and the appropriate conditions are obtained. The result showed the microemulsion has great efficiency for uranium(VI) extraction.     

Separation of the Oxyanions of Re(VII), Mo(VI), Cr(VI), W(VI), and V(V) from a Multicomponent Solution at pH 6 by foam Fractionation

Abstract

An experimental investigation is presented of the foam separation of the oxyanions of Re(VII), Mo(VI), Cr(VI), W(VI), and V(V). The pH 6.0, multicomponent aqueous solutions are 1.0 × 10 ^?6 M in each metal. The effect of chloride competition with the metal oxyanions for the cationic surfactant is determined with NaCl concentrations up to 0.3 M. With proper NaCl concentration adjustments, V(V) can be separated completely from the other four metals, and Re(VII) and Mo(VI) from the other three. Pulsed surfactant dosage is investigated for 1.0 × 10 ^?6 M Mo(VI) solutions at pH 6.0 and 3.1.     

Liquid-liquid extraction of Mo(VI) and V(V) by Primene JMT

The extraction equilibrium of pentavalent vanadium and hexavalent molybdenum with a benzene solution of primary amine Primene JMT sulphate has been investigated. The comparison of the extraction of aqueous solutions containing the salts of the elements and the solutions containing the mixture of Mo(VI) and V(V) was carried out. The attention was directed to the pH 2–6 region in which the heptamolybdates and decavanadates in prevail aqueous phase and to the region ≈1M H₂SO₄ which was suitable for the extraction separation of Mo(VI). The mechanism of extraction is discussed.     

Solvent extraction of Mo(V) and Mo(VI) from hydrochloric acid into Aliquat 336 chloroform solution

Solvent extraction of macro amounts of Mo(V) and Mo(VI) from HCl using Aliquat 336 in chloroform was performed for the electrochemistry of Sg. The extraction reaction attained equilibrium with a shaking time of 10 s in higher than 8 M HCl. The D values of Mo(V) obtained by the electrochemical reduction of Mo(VI) were in good agreement with those obtained by the extraction of MoCl₅, and the D values of Mo(V) were higher than those of Mo(VI). These results suggested that the reduction behavior of Sg might be studied by electrochemical reduction combined with the present solvent extraction.     

Solvent extraction of technetium(VII) by primary amine in heptane solution from aqueous alkaline solution

Technetium(VII) extraction has been investigated to obtain useful information concerming the back-extraction of Tc(VII). Radioactive technetium-95m was used to determine the distribution ratio (D _Tc) of^95mTcO ₄ ^– for Tc(VII) extraction using Primene JMT (RNH₂) in heptane solution. An emulsion formation did not occur in the ammonium carbonate system but occurred in the sodium hydroxide solutions. The extraction mechanism has also determined by using the slope analysis method to study the relationships between logD _Tc and log [RNH₂], and between logD _Tc and pH.     

Technetium(VII) extraction by a primary amine and technetium(VII) coprecipitation with ammonium diuranate in hydrofluoric acid solution

The separation of technetium(VII) from uranium(VI) has beeen studied through experiments on the coprecipitation of Tc(VII) with ammonium diuranate precipitate, and in the extraction of Tc(VII) from an aqueous hydrofluoric acid solution using a primary amine (Primene JMT) as an extractant dissolved inn-heptane. The extraction of Tc(VII) reached a quantitative level after several repetitions of the extraction procedure. Also, the stripping of Tc(VII) into 3M aqueous solution of ammonium carbonate was enhanced to a level over 99% by repeating the stripping cycles.     

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.     

Efficacious selective separation of U(VI) over Mo(VI) using novel 2,9-diamide-1,10-phenanthroline ligands: Liquid-liquid extraction and coordination chemistry

Uranium and molybdenum are important strategic elements. The production of ⁹⁹Mo and the hydrometallurgical process of uranium ore face difficult problems of separation of uranium and molybdenum. In this study, the four phenanthroline diamide ligands were synthesized, and extraction and stripping experiments were performed under different conditions to evaluate the potential application of these ligands for separation of U(VI) over Mo(VI). With the growth of alkyl chain, the solubility of ligands could be greatly improved, and the separation effect of U(VI) over Mo(VI) gradually increased. The SF_U/Mo were around 10,000 at 4 mol/L HNO₃. Three stripping agents were tested with the stripping efficiency of Na₂CO₃ (5%) > H₂O > HNO₃ (0.01 mol/L). The stripping percentages of the three stripping agents were all close to unity, indicating that the ligands had the potential to be recycled. The chemical stoichiometry of U(VI) complexes with ligands was evaluated as 1:1 using electrospray ionization mass spectrometry, ultraviolet visible spectroscopy and single-crystal X-ray diffraction. The consistency between theoretical calculation and experimental results further explains the coordination mechanism.     

Rapid separation of VI/VII technetium oxidation states by solvent extraction with iodonitrotetrazolium chloride

Technetium⁹⁹ poses a difficult problem at many nuclear waste disposal sites, as there have been multiple incidents of its release to the environment due to large quantities of fission products disposed in storage tanks. Tc is mostly present under two oxidation states, Tc(VII) and Tc(IV) and the separation of Tc(IV) from Tc(VII) is often crucial for laboratory-scale work performed for the study of Tc. This work offers a method for the rapid separation of Tc(IV) from Tc(VII), using a solvent extraction system containing iodonitrotetrazolium chloride and chloroform.     

Separation and concentration of molybdenum(VI) and tungsten(VI) with chelating ion-exchange resins containing sulphur ligands

Three chelating ion-exchange resins based on macroreticular polyacrylonitrile-divinylbenzene copolymers with thioglycollic acid and cysteine as functional groups have been tested for separation of molybdenum(VI) and tungsten(VI). On a short column of the thioglycollic acid resin, molybdenum(VI) and tungsten(VI) can be selectively sorbed from pH-4.3 acetate buffer and eluted with 2M hydrochloric acid and a mixture of 0.1M sodium hydroxide and 0.1M sodium chloride, respectively, with quantitative recovery even at very low concentrations. Simulated sea-water samples have been analysed.     

Diffusion of Re(VII), Se(IV) and Cr(VI) in compacted GMZ bentonite

Journal of Radioanalytical and Nuclear Chemistry - The diffusion of Re(VII), Se(IV) and Cr(VI) in compacted Gaomiaozi bentonite was conducted by an integrated diffusion setup. The effective...     

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.     

Adsorbing colloid flotation separation and polarographic determination of Mo(VI) in water

A method is described for the flotation and determination of Mo(VI) in water at ng/ml levels. Mo(VI) is preconcentrated and separated by adsorbing colloid flotation employing aluminium(III) hydroxide as collector and sodium lauryl sulphate as surfactant at pH 5.3 ± 0.1. The molybdenum content in the froth is estimated by using the catalytic wave of Mo(VI) in the presence of nitrate by charging current compensated d.c. polarography (CCCDCP) or differential pulse polarography (DPP). The effect of variables such as pH, ionic strength, concentration of collector and surfactant, time of stirring and gas flow-rate on the recovery of Mo by flotation is reported. The effects of various cations and anions on the flotation and determination of Mo are studied. This method is employed for the determination of molybdenum in natural fresh water samples.     

Preconcentrative separation of chromium(III) species from chromium(VI) by cloud point extraction and determination by flame atomic absorption spectrometry

Microchimica Acta - We describe a high-throughput technique for the determination of chromium species in water samples by flame atomic absorption spectrometry (FAAS) after preconcentrative...     

Separation of Tc(VII) from Tc(IV) by solvent extraction

The solvent extraction of Tc(IV) and Tc(VII) by isoamyl alcohol has been studied. The TcCl ₆ ²⁻ and TcO ₄ ⁻ ions are both extracted from 3M H₂SO₄ solution but hydrolyzed Tc(IV) species are not. This permits the separation of the two valence states of technetium. The air oxidation of carrier-free hydrolyzed^99mTc(IV) may be limited by the presence of⁹⁹Tc carrier in the same chemical form. Paper chromatography and electrophoresis were used to identify TcCl ₆ ²⁻ , TcO ₄ ⁻ and hydrolyzed species. It was also found that the hydrolyzed ReCl ₆ ²⁻ can reduce TcO ₄ ⁻ to Tc(IV).     

Solvent extraction of technetium(VII) by 4-(5-nonyl)pyridine and its separation from uranium and some fission products

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.     

纳米TiO2分离富集Mo(Ⅵ)和Re(Ⅶ)

本文研究了纳米TiO2吸附剂对Mo(VI)、Re(VII)的吸附行为,考察了溶液的pH值、吸附时间、温度等因素对吸附的影响。结果表明：纳米TiO2对Mo(VI)的吸附在pH 1～8条件下,吸附率超过99%,2 mL 0.05mol/L NaOH溶液可将吸附的Mo(VI)离子完全洗脱,解吸率能达到97%。在pH 1～10范围内,纳米TiO2不吸附Re(VII), 从而达到Mo(VI)、Re(VII)分离。在2℃～50℃温度范围内,Mo(VI)的吸附过程符合Langmiur等温式,纳米TiO2对Mo(VI)的最大吸附容量从11.51mg g-1增加到14.19 mg g-1;纳米TiO2分离钼后,溶液剩余的铼,用活性炭吸附,在pH1～10范围内, Re(VII)的吸附率可达99%,用浓氨水进行洗脱,洗脱率可达96%;吸附过程可用准二级反应动力学模型描述,是以化学吸附为控制步骤的吸附过程;吸附等温线与Freundlich模型有较好的拟合。