Speciation of technetium peroxo complexes in sulfuric acid revisited
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The reaction of Tc(+7) with H2O2 has been studied in H2SO4 and the speciation of technetium performed by UV–visible and 99-Tc NMR spectroscopy. UV–visible measurements show that for H2SO4 ≥ 9 M and H2O2 = 0.17 M, TcO3(OH)(H2O)2 reacts immediately and blue solutions are obtained, while no reaction occurs for H2SO4 < 9 M. The spectra of the blue solutions exhibit bands centered around 520 and 650 nm which are attributed to Tc(+7) peroxo species. Studies in 6 M H2SO4 show that TcO4 − begins to react for H2O2 = 2.12 M and red solutions are obtained. The UV–visible spectra of the red species are identical to the one obtained from the reaction of TcO4 − with H2O2 in HNO3 and consistent with the presence of TcO(O2)2(H2O)(OH). The 99-Tc NMR spectrum of the red solution exhibits a broad signal centered at +5.5 ppm vs TcO4 − and is consistent with the presence of a low symmetry Tc(+7) molecule.
KeywordsTechnetium Peroxo complexes Speciation Sulfuric acid
Funding for this research was provided by the U.S. Department of Energy, Office of Nuclear Energy, NEUP grant through INL/BEA, 321 LLC, 00129169, agreement number DE-AC07-05ID14517. Further supports were provided by the National Science Foundation (Grant NSF-CHE 0750118 and Grant NSF-CHE-0959617 for purchase of the 400 MHz NMR spectrometer at Hunter College) and the U. S Department of Energy, Grant DE-FG02- 09ER16097 (Heavy Element Chemistry, Office of Science) and Grant DE-SC0002456 (Biological and Environmental Research, Office of Science). Infrastructure at Hunter College is partially supported by Grant RR003037 from the National Center for Research Resources (NCRR), a component of the National Institutes of Health (NIH). Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under Contract DE-AC04-94AL85000. The authors thank Trevor Low and Julie Bertoia for outstanding health physics support.
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