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Yokoyama, Akihiko*; Kitayama, Yuta*; Fukuda, Yoshiki*; Kikunaga, Hidetoshi*; Murakami, Masashi*; Komori, Yukiko*; Yano, Shinya*; Haba, Hiromitsu*; Tsukada, Kazuaki; Toyoshima, Atsushi*
Radiochimica Acta, 107(1), p.27 - 32, 2019/01
Times Cited Count:1 Percentile:11.41(Chemistry, Inorganic & Nuclear)Oe, Kazuhiro*; Attallah, M. F.*; Asai, Masato; Goto, Naoya*; Gupta, N. S.*; Haba, Hiromitsu*; Huang, M.*; Kanaya, Jumpei*; Kaneya, Yusuke*; Kasamatsu, Yoshitaka*; et al.
Journal of Radioanalytical and Nuclear Chemistry, 303(2), p.1317 - 1320, 2015/02
Times Cited Count:8 Percentile:61(Chemistry, Analytical)A new technique for continuous dissolution of nuclear reaction products transported by a gas-jet system was developed for superheavy element (SHE) chemistry. In this technique, a hydrophobic membrane is utilized to separate an aqueous phase from the gas phase. With this technique, the dissolution efficiencies of short-lived radionuclides of Mo and W were measured. Yields of more than 80% were observed for short-lived radionuclides at aqueous-phase flow rates of 0.1-0.4 mL/s. The gas flow-rate had no influence on the dissolution efficiency within the studied flow range of 1.0-2.0 L/min. These results show that this technique is applicable for on-line chemical studies of SHEs in the liquid phase.
Oe, Kazuhiro; Tsukada, Kazuaki; Asai, Masato; Sato, Tetsuya; Toyoshima, Atsushi; Miyashita, Sunao; Nagame, Yuichiro; Schdel, M.; Kaneya, Yusuke*; Lerum, H. V.*; et al.
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We are planning to investigate the redox behavior of element 106, seaborgium (Sg). For the Sg study, we newly developed a continuous dissolution apparatus which dissolves the gas-jet transported nuclides produced in nuclear reactions into aqueous solution. The new apparatus has a hydrophobic membrane filter for separation of aqueous solution from the gas. We investigated the dissolution efficiencies with the apparatus for short-lived nuclides of molybdenum and tungsten which are lighter homologues of Sg. In the meeting, the dependence of the efficiencies on the aqueous- and gas-flow rates will be reported.
Miyashita, Sunao; Oe, Kazuhiro; Toyoshima, Atsushi; Sato, Tetsuya; Asai, Masato; Tsukada, Kazuaki; Nagame, Yuichiro; Schdel, M.; Kaneya, Yusuke*; Omtvedt, J. P.*; et al.
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For the experiments of the redox potentials of Sg, rapid separation between different oxidation states of Sg is needed. In this study, solvent extraction of hexavalent Mo and W, as the lighter homologues of Sg, from 1.0 mol/L hydrochloric acid solution into di-(2-ethylhexyl)phosphoric acid (HDEHP), 1-phenyl-3-metyl-4-benzoyl-5-pyrazolone (PMBP), N-benzoyl-N-pheny-hydroxylamine (BPHA) and 4-isopropyl-tropolone (HT) in toluene was carried out. When HDEHP and PMBP were used as extractant, extraction equilibrium of W was achieved within 5 and 1 hours respectively. On the other hand, when BPHA and HT were used, extraction equilibrium of W was quickly achieved within 1 minute in both extractants. Extraction kinetics of Mo using BPHA and HT was examined. Extraction kinetics of Mo was slower than that of W. Extraction equilibrium of Mo was achieved within 10 by BPHA and 3 minutes by HT. We concluded that HT is a suitable extractant for the Sg reduction experiment.
Miyashita, Sunao; Toyoshima, Atsushi; Oe, Kazuhiro*; Asai, Masato; Sato, Tetsuya; Tsukada, Kazuaki; Nagame, Yuichiro; Schdel, M.; Kaneya, Yusuke; Haba, Hiromitsu*; et al.
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Solvent extraction of Mo and W using 4-isopropyltropolone (Hinokitiol, HT) was investigated. Extraction mechanism of Mo and W with HT was examined by slope analysis. The slopse of the distribution ratio of Mo and W vs. [HT] in logarithmic scale are 1.88 and 1.54, respectively.
Miyashita, Sunao; Toyoshima, Atsushi; Oe, Kazuhiro*; Sato, Tetsuya; Asai, Masato; Tsukada, Kazuaki; Nagame, Yuichiro; Schdel, M.; Kaneya, Yusuke; Haba, Hiromitsu*; et al.
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The extraction behavior of hexavalent and reduced Mo and W were investigated when aqueous phase was 0.1 M HCl/0.9 M LiCl solution. The D value of Mo was changed from 10 to 1 when applied potential was near 0 to -0.2 V. On the other hand, the D value of W was not changed at all applied potentials in this experimental condition. Those results indicated that Mo was reduced by FEC, and the extraction behavior of reduced Mo was different from hexavalent Mo. In the case of W, W was not reduced or the D values of reduced W was same as hexavalent W.
Toyoshima, Atsushi; Miyashita, Sunao*; Asai, Masato; Sato, Tetsuya; Kaneya, Yusuke; Tsukada, Kazuaki; Kitatsuji, Yoshihiro; Nagame, Yuichiro; Schdel, M.; Lerum, H. V.*; et al.
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To carry out a continuous reduction experiment of Sg with the low production rates and the short half-life, we are developing a new chemistry assembly consisting of a membrane degasser (MDG), a flow electrolytic column (FEC), the continuous liquid-liquid extraction apparatus, and the liquid scintillation counting system (SISAK). Recently, we have begun preparatory studies with Mo and W isotopes. Aqueous solution dissolving Mo and W was successfully separated from a carrier gas. Redox couples of Mo(VI)/Mo(V) and W(VI)/W(V) in HCl have been characterized for their macro amounts. Extraction behavior of Mo(VI) and W(VI) between toluene containing hinokitiol (HT) and HCl was successfully observed by a batch method. On-line extractions of short-lived Mo and W were also carried out using SISAK and MDG. In the symposium, our present status of the preparation with Mo and W will be presented.
Toyoshima, Atsushi; Asai, Masato; Attallah, M. F.*; Goto, Naoya*; Gupta, N. S.*; Haba, Hiromitsu*; Huang, M.*; Kanaya, Jumpei*; Kaneya, Yusuke; Kasamatsu, Yoshitaka*; et al.
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Towards electrolytic reduction of Sg, batch-wise electrolytic reduction of carrier-free Mo and W radiotracers was studied using a flow electrolytic column (FEC). The electrolyzed samples from a FEC were chemically analyzed by solvent extraction with TOA and HDEHP to separate and identify reduced species from the stable Mo(VI) and W(VI) ones based on their different extraction behavior. Mo and W were applied as radiotracers. We also performed cyclic voltammetry and UV/Vis absorption spectrometry of macro amounts of Mo and W in acidic solutions to obtain information on redox reactions of these elements under given conditions. In the conference, the present status of the preparatory reduction experiments with Mo and W will be presented.
Toyoshima, Atsushi; Miyashita, Sunao*; Oe, Kazuhiro*; Kitayama, Yuta*; Lerum, H. V.*; Goto, Naoya*; Kaneya, Yusuke; Komori, Yukiko*; Mitsukai, Akina*; Vascon, A.; et al.
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no abstracts in English
Toyoshima, Atsushi; Oe, Kazuhiro*; Asai, Masato; Attallah, M. F.*; Goto, Naoya*; Gupta, N. S.*; Haba, Hiromitsu*; Kaneko, Masashi*; Kaneya, Yusuke; Kasamatsu, Yoshitaka*; et al.
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Due to short half-lives less than 10 s and extremely low production rates, transactinide elements heavier than seaborgium (Sg) are produced on an atom per hour scale. Therefore, a continuous rapid chemistry assembly is required to study aqueous-phase chemistry of these heaviest elements. In the present study, we started developments of a continuous chemistry assembly. Our first attempt was made in on-line experiments with Mo and W, lighter homologs of Sg, to optimize a chemistry assembly consisting of a newly developed membrane degasser as an interface between gas-jet and aqueous phase, a flow electrolytic column apparatus utilized to control oxidation states of Mo and W ions, and the continuous liquid-liquid extraction apparatus of SISAK for separation. In the conference, present status of the developments will be presented.