Spontaneous redox continuum reveals sequestered technetium clusters and retarded mineral transformation of iron

Autor:	Gabriel B. Hall, Edgar C. Buck, Daria Boglaienko, Tatiana G. Levitskaia, Yelena Katsenovich, Vanessa E. Holfeltz, Jennifer A. Soltis, Carlo U. Segre, Lucas E. Sweet, Yingge Du, Ravi K. Kukkadapu, Hilary P. Emerson
Jazyk:	angličtina
Rok vydání:	2020
Předmět:	Pertechnetate Inorganic chemistry Iron oxide chemistry.chemical_element 02 engineering and technology 010501 environmental sciences Technetium 01 natural sciences Biochemistry Redox Metal lcsh:Chemistry Ferrihydrite chemistry.chemical_compound Materials Chemistry Environmental Chemistry 0105 earth and related environmental sciences Magnetite Zerovalent iron General Chemistry 021001 nanoscience & nanotechnology chemistry lcsh:QD1-999 visual_art visual_art.visual_art_medium 0210 nano-technology
Zdroj:	Communications Chemistry, Vol 3, Iss 1, Pp 1-11 (2020)
ISSN:	2399-3669
Popis:	The sequestration of metal ions into the crystal structure of minerals is common in nature. To date, the incorporation of technetium(IV) into iron minerals has been studied predominantly for systems under carefully controlled anaerobic conditions. Mechanisms of the transformation of iron phases leading to incorporation of technetium(IV) under aerobic conditions remain poorly understood. Here we investigate granular metallic iron for reductive sequestration of technetium(VII) at elevated concentrations under ambient conditions. We report the retarded transformation of ferrihydrite to magnetite in the presence of technetium. We observe that quantitative reduction of pertechnetate with a fraction of technetium(IV) structurally incorporated into non-stoichiometric magnetite benefits from concomitant zero valent iron oxidative transformation. An in-depth profile of iron oxide reveals clusters of the incorporated technetium(IV), which account for 32% of the total retained technetium estimated via X-ray absorption and X-ray photoelectron spectroscopies. This corresponds to 1.86 wt.% technetium in magnetite, providing the experimental evidence to theoretical postulations on thermodynamically stable technetium(IV) being incorporated into magnetite under spontaneous aerobic redox conditions. For the geological disposal of radionuclides through immobilization within minerals, naturally aerobic conditions need to be considered. Here the authors report a quantitative reduction of Tc7+ and partial structural incorporation of Tc4+ into in situ formed nonstochiometric magnetite under ambient conditions.
Databáze:	OpenAIRE
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