Redox interactions of Tc(VII), U(VI), and Np(V) with microbially reduced biotite and chlorite
Brookshaw, Diana R. and Pattrick, Richard A.D. and Bots, Pieter and Law, Gareth T. W. and Lloyd, Jonathan R. and Mosselmans, J. Fredrick W. and Vaughan, David J. and Dardenne, Kathy and Morris, Katherine (2015) Redox interactions of Tc(VII), U(VI), and Np(V) with microbially reduced biotite and chlorite. Environmental Science and Technology, 49 (22). pp. 13139-13148. ISSN 0013-936X (https://doi.org/10.1021/acs.est.5b03463)
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Abstract
Technetium, uranium, and neptunium are contaminants that cause concern at nuclear facilities due to their long half-life, environmental mobility, and radiotoxicity. Here we investigate the impact of microbial reduction of Fe(III) in biotite and chlorite and the role that this has in enhancing mineral reactivity toward soluble TcO4 -, UO2 2+, and NpO2 +. When reacted with unaltered biotite and chlorite, significant sorption of U(VI) occurred in low carbonate (0.2 mM) buffer, while U(VI), Tc(VII), and Np(V) showed low reactivity in high carbonate (30 mM) buffer. On reaction with the microbially reduced minerals, all radionuclides were removed from solution with U(VI) reactivity influenced by carbonate. Analysis by X-ray absorption spectroscopy (XAS) confirmed reductive precipitation to poorly soluble U(IV) in low carbonate conditions and both Tc(VII) and Np(V) in high carbonate buffer were also fully reduced to poorly soluble Tc(IV) and Np(IV) phases. U(VI) reduction was inhibited under high carbonate conditions. Furthermore, EXAFS analysis suggested that in the reaction products, Tc(IV) was associated with Fe, Np(IV) formed nanoparticulate NpO2, and U(IV) formed nanoparticulate UO2 in chlorite and was associated with silica in biotite. Overall, microbial reduction of the Fe(III) associated with biotite and chlorite primed the minerals for reductive scavenging of radionuclides: this has clear implications for the fate of radionuclides in the environment.
ORCID iDs
Brookshaw, Diana R., Pattrick, Richard A.D., Bots, Pieter ORCID: https://orcid.org/0000-0001-6863-0648, Law, Gareth T. W., Lloyd, Jonathan R., Mosselmans, J. Fredrick W., Vaughan, David J., Dardenne, Kathy and Morris, Katherine;-
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Item type: Article ID code: 56746 Dates: DateEvent17 November 2015Published21 October 2015Published Online21 October 2015AcceptedSubjects: Science > Chemistry Department: Faculty of Engineering > Civil and Environmental Engineering Depositing user: Pure Administrator Date deposited: 27 Jun 2016 10:12 Last modified: 07 Oct 2024 08:10 URI: https://strathprints.strath.ac.uk/id/eprint/56746