Anion-exchange behavior of Mo and W as homologs of Sg (element 106) in HCl and HNO3 as well as in mixed HCl-HF and HNO3-HF solutions

Isolation and quantification of a 93Mo isotope solution from proton irradiated niobium

⁹³Mo (4000 y half-life) formed through the ⁹³Nb(p,n)⁹³Mo reaction was isolated from a niobium target foil previously used in a low energy medical cyclotron. ⁹³Mo has identical characteristic x-ray emission and mass as the isomer ^93mNb and stable Nb present in the target foil at much higher concentrations. This makes distinction between ⁹³Mo, ^93mNb and stable Nb difficult using radiometric or mass spectrometric methods. An anion exchange method in combination with x-ray spectrometry and ICP-MS/OES enabled quantitative isolation of about 0.4 μg ⁹³Mo (14 kBq) from ^93mNb with a separation factor >10⁴ on a single column. An extraction chromatography column (TEVA) was used to reach a^93mNb/⁹³Mo activity ratio of <10^-6 and an atom ratio ⁹³Nb/⁹³Mo <1% making the ⁹³Mo suitable for both radiometric and mass spectrometric testing. ⁹³Mo is the only radioisotope of molybdenum with a long enough half-life suitable for this purpose. Calibration of the ⁹³Mo isotope solution was done through x-ray spectrometry using a characterized BEGe-detector in combination with a^99mTc solution. This is the first reported isolation of a⁹³Mo solution in the literature and the first time a LSC-spectrum of ⁹³Mo is shown.

Extraction of carrier-free 99Mo by ionic liquids from acid solutions: A model of seaborgium (Sg) experiment

A new approach for extraction of ⁹⁹Mo tracer as a lighter homolog of Seaborgium (Sg) by three different the ionic liquids are studied. Aliquat-336 [Aliq-336.Cl^-] as anion exchange has been used for the preparation of three ionic liquid, namely: ([Aliq-336]⁺ [SCN]^-), ([Aliq-336]⁺ [S]^- ) and ([Aliq-336]⁺ [Fe(CN)₆]^-). Their potential extraction of carrier free ⁹⁹Mo from HNO₃ solutions has been evaluated. The obtained results demonstrated that successful extraction of carrier free ⁹⁹Mo from HNO₃ solutions is achieved. The ([Aliq-336]⁺ [Fe(CN)₆]^-) is found to give the highest extraction affinity for ⁹⁹Mo than the others ionic liquids investigated. The preliminary results could be useful for the upcoming aqueous experiments of Seaborgium.

Chemical separation of Mo and W from terrestrial and extraterrestrial samples via anion exchange chromatography

A new two-stage chemical separation method was established using an anion exchange resin, Eichrom 1 × 8, to separate Mo and W from four natural rock samples. First, the distribution coefficients of nine elements (Ti, Fe, Zn, Zr, Nb, Mo, Hf, Ta, and W) under various chemical conditions were determined using HCl, HNO3, and HF. On the basis of the obtained distribution coefficients, a new technique for the two-stage chemical separation of Mo and W, along with the group separation of Ti-Zr-Hf, was developed as follows: 0.4 M HCl-0.5 M HF (major elements), 9 M HCl-0.05 M HF (Ti-Zr-Hf), 9 M HCl-1 M HF (W), and 6 M HNO3-3 M HF (Mo). After the chemical procedure, Nb remaining in the W fraction was separated using 9 M HCl-3 M HF. On the other hand, Nb and Zn remaining in the Mo fraction were removed using 2 M HF and 6 M HCl-0.1 M HF. The performance of this technique was evaluated by separating these elements from two terrestrial and two extraterrestrial samples. The recovery yields for Mo, W, Zr, and Hf were nearly 100% for all of the examined samples. The total contents of the Zr, Hf, W, and Mo in the blanks used for the chemical separation procedure were 582, 9, 29, and 396 pg, respectively. Therefore, our new separation technique can be widely used in various fields of geochemistry, cosmochemistry, and environmental sciences and particularly for multi-isotope analysis of these elements from a single sample with significant internal isotope heterogeneities.

Aqueous-phase chemistry of the transactinides

The experimental techniques developed to perform rapid chemical separations of the heaviest elements in the aqueous phase are presented. In general, these include transport of the nuclear reaction products to a separation device by the gas-jet technique and dissolution in an aqueous solution containing inorganic ligands for complex formation. The complexes are chemically characterized by a partition method which can be liquid–liquid extraction, ion-exchange- or reversed-phase extraction chromatography. The separated fractions are quickly evaporated to dryness for the preparation of samples for α-particle spectroscopy. Comments are given on the special situation in which chemistry has to be studied with single atoms. Theoretical predictions of chemical properties are compared to the presently known chemical behaviour of rutherfordium, Rf (element 104), dubnium, Db (element 105), seaborgium, Sg (element 106), and hassium, Hs (element 108) and to that of their lighter homologs in the Periodic Table in order to assess the role of relativistic effects in the chemistry of the heaviest elements.

Theoretical treatment of the complexation of element 106, Sg, in HF solutions

Fully relativistic density-functional calculations of the electronic structures of various oxo-fluoro-complexes were performed for group-6 elements Mo, W, and element 106, Sg. Based on the electronic density distribution data, relative values of the free energy change of complex formation reactions in HF solutions have been defined. On their basis, sequences in the sorption of Mo, W, and Sg by an anion exchange resin (Kdvalues) have been predicted. The results show a complex situation depending on the acid concentration and pH of the solution. The predicted trends are in agreement with the known data for Mo and W. The following sequence in the sorption of Mo, W, and Sg by an anion exchange resin from 5×10-3HF/0.1 M HNO3solutions is predicted: Mo>Sg>W. A very good separation of Sg from Mo and W is expected at concentrated HF solutions, where MOF5-is formed. The sequence of the sorption in this case should be Sg ≫W > Mo.

Separation of Trace Level Hafnium from Tungsten: A Step Toward Solving an Astronomical Puzzle

182Hf (T(1/2) = 9 x 10(6) y) is believed to be formed by pure r-process during a supernova explosion, and therefore, the search for minute traces of 182Hf in the earth's crust is of great interest. Only accelerator mass spectrometry (AMS) is well suited for detecting such low levels of 182Hf. But any attempt to measure 182Hf by AMS must ensure that the sample is free from its naturally occurring stable isobar 182W. A simple method for separation of tungsten and hafnium has been developed using radiometric simulation followed by checking the decontamination of tungsten from Hf in a synthetic sample by AMS. The separation studies were performed by a liquid-liquid extraction technique using tri-n-octylamine (TOA) as the organic reagent. It has been found that a very high separation factor (1.6 x 10(6)) can be achieved when 0.3 M TOA diluted in cyclohexane is used as the organic phase and 6 M HCl (in the presence of small amount of H2O2) is used as the aqueous phase.