99Tc immobilization by aluminum solids containing Fe(II) moieties
Natalia Mayordomo1, Diana M. Rodríguez1, Konrad Molodtsov1, Erik V. Johnstone2, André Rossberg1,3, Karsten Heim1, Harald Foerstendorf1, Dieter Schild4, Vinzenz Brendler1 and Katharina Müller1.
1Helmholtz-Zentrum Dresden-Rossendorf (HZDR). Institute of Resource Ecology, Bautzner Landstrasse 400, 01328 Dresden (Germany).
2Innovative Fuel Solutions (IFS), North Las Vegas, NV (USA).
3The Rossendorf Beamline at ESRF, 71 Ave. des Martyrs, 38043 Grenoble (France).
4Karlsruhe Institute of Technology (KIT). Institute for Nuclear Waste Disposal (INE), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Karlsruhe (Germany).
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.
(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.
This work has been developed in the frame of the VESPA II project (02E11607B), supported by the German Federal Ministry of Economic Affairs and Energy (BMWi). N.M acknowledges the support of Jörg Rothe and Kathy Dardenne for their help at the KARA beamline at KIT (Karlsruhe).