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⁹⁹Tc immobilization by aluminum solids containing Fe(II) moieties
Mayordomo Herranz, N.ORC; Rodriguez Hernandez, D. M.; Molodtsov, K.; Johnstone, Erik V.; Roßberg, A.; Heim, K.; Foerstendorf, H.ORC; Schild, Dieter; Brendler, V.ORC; Müller, K.ORC
The immobilization of ⁹⁹Tc is predominantly mediated by the reduction of Tc(VII) to Tc(IV), primarily due to the fact that [Tc(VII)O₄] ⁻ interactions with solid interfaces are limited, whereas Tc(IV)O₂ is a hardly soluble solid [1]. Tc reduction is facilitated by Fe²⁺, particularly when it is present as a sorbed species or a constituent mineral phase [2].
The present work analyzes the ⁹⁹Tc aqueous removal by two aluminum solids containing Fe(II) moieties: γ-Al₂O₃ with sorbed Fe²⁺ and Fe(II)-Al(III) layered double hydroxide (LDH). Batch contact experiments demonstrate that both solids are effective Tc scavengers, yielding a complete removal for pH > 6.5 and from pH 3.5 to 10.5, respectively. Characterization via XPS, XAS, and in situ ATR FT-IR spectroscopy provided information of the Tc speciation and uptake mechanism. Secondary Fe-minerals (hematite, magnetite, ferrihydrite) formed in the reduction were also identified by Raman microscopy.

Bibliography
[1] Meena, A. H.; Arai, Y. Env. Chem Lett 2017, 15, 241–263.
[2] Cui, D.; Eriksen, T. E. Environ. Sci. Technol. 1996, 30 (7), 2259–2262.
  • Lecture (Conference)
    The 43th symposium on scientific basis for nuclear waste management, 21.-24.10.2019, Viena, Austria

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Publ.-Id: 29778