Impact of nitrate on the redox chemistry and solubility of Tc(IV) in alkaline, dilute to concentrated aqueous NaCl solutions
- Karlsruhe Institute of Technology, Karlsruhe (Germany)
- Karlsruhe Institute of Technology, Karlsruhe (Germany); Los Alamos National Lab. (LANL), Carlsbad, NM (United States)
Here, the impact of nitrate on the redox behaviour and solubility of 99Tc(IV) was investigated in 0.1–5.0 M NaCl–NaNO3–NaOH solutions with 0.1 M ≤ [NO3–] ≤ 1.0 M and 8.5 ≤ pHm ≤ 14.5 (with pHm = –log [H+]) in the presence or absence of reducing agents (as Fe powder, Na2S2O4, Sn(II)). The evolution of the redox conditions as a function of time (for t ≤ 450 days) was investigated: (i) in the absence of technetium (inactive samples), (ii) in the presence of 99Tc(IV) (added as 1–2 mg of TcO2∙0.6H2O(am)), and (iii) in the presence of 137Cs(I) (and absence of 99Tc). All experiments were conducted in an Ar-glovebox (O2 < 1 ppm) at T = (22 ± 2) °C. An improved understanding of Tc redox processes in nitrate-rich alkaline solutions is relevant to predict Tc behaviour in specific nuclear waste disposal scenarios and a topic of fundamental scientific interest.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- Universities/Institutions; USDOE
- Grant/Contract Number:
- AC52-06NA25396
- OSTI ID:
- 1477725
- Report Number(s):
- LA-UR-18-20528
- Journal Information:
- Applied Geochemistry, Vol. 98, Issue C; ISSN 0883-2927
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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