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URN: urn:nbn:de:swb:90-AAA2301038881

U redox state and speciation of U in contact with magnetite nanoparticles : High resolution XANES, EXAFS, XPS and TEM study

Pidchenko, I.; Kvashnina, K.; Yokosawa, T.; Finck, N.; Schild, S.; Schäfer, T.; Rothe, J.; Geckeis, H.; Vitova, T.

Abstract:
Long-term storage of high-level radioactive waste is associated with potential radioecological hazards.
One chemical element of high interest is uranium (U), which can mainly exists as a mobile U(VI)
(oxidizing conditions) and sparingly soluble U(IV) (reducing conditions) species. It is expected that
the main inorganic reducing agent for U(VI) in the environment are ferrous species in magnetite,
formed on the steel canisters surface as an intermediate iron (Fe) corrosion product [1]. Results
obtained from laboratory experiments for the interaction of U(VI) with magnetite nanoparticles point
to partial reduction of U(VI) [2] or the formation of ~3 nm uranium dioxide (UO₂) particles on the
surface layer [3]. The evidence for U(VI) reduction to intermediate U(V) state was found with no
direct evidence of U(IV), which is in contradiction with thermodynamic calculations [4]. Continuous
interaction and related phase dissolution/recrystallization processes can also lead to U redox changes
and structural U incorporation into Fe oxides, resulting in U immobilization [5]. U redox state and
speciation analyses are still very challen ... mehr


Zugehörige Institution(en) am KIT Institut für Nukleare Entsorgung (INE)
Publikationstyp Vortrag
Jahr 2015
Sprache Englisch
Identifikator URN: urn:nbn:de:swb:90-AAA2301038881
KITopen ID: 230103888
HGF-Programm 32.27.04; LK 01
Erschienen in 15th International Conference on the Chemistry and Migration Behaviour of Actinides and Fission Products in the Geosphere (Migration 2015), Santa Fe, New Mexico, 13th - 18th September 2015
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