ИСТИНА

The rhenium(VII) and technetium(VII) behavior in extraction systems is known to be strongly affected by the presence of zirconium. Recently the hydrolyzed form of zirconium perrhenate and pertechnetate were shown to form the dimeric {Zr2(OH)2} core surrounded by six permetallate anions acting as monodentate ligands and six coordination water molecules [1,2]. It was shown [1, 2] that usually very stable tetramer [Zr4(OH)8(H2O)16]8+ undergoes dissociation in the presence of TcO4–/ReO4– yielding isostructural dimers, [Zr2(µ-OH)2(MO4)6 (H2O)6] 3H2O (M = Tc, Re) that is very close to zirconyl in view of Zr:O ratio. In this frame the formation of Tc(VII)-Zr(IV) species in nitric acid and their extraction in kerosene/tributylphosphate (TBP) phases was re-examined. The technetium distribution coefficient (DTc) was evaluated as a function of nitric acid concentration (1-7 M) and is in the range of 25-37, which is significantly higher compared to solutions that do not contain zirconium and confirms the synergism of their coextraction. [1] Novikov, A.P., Zagidullin, K.A., Kuznetsov, V.V. et al. Speciation and Complex Formation of Zirconium(IV) with Tc(VII) and Re(VII) in Liquid–Liquid Extraction Systems. ACS Omega, 2025, V. 10.Is. 33. 38064-38072. doi: 10.1021/acsomega.5c05158 [2] Shohel, M.; Bustos, J.; Roseborough, A.; Nyman, M. Pertechnetate/Perrhenate‐capped Zr/Hf‐Dihydroxide Dimers: Elucidating Zr−TcO 4 Co‐Mobility in the Nuclear Fuel Cycle. Chem. – A Eur. J. 2024, 30 (10), e202303218. https://doi.org/10.1002/chem.202303218.