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Uranium fate during crystallization of magnetite from ferrihydrite in conditions relevant to the disposal of radioactive waste

DOI: 10.1180/minmag.2015.079.6.02 DOI Help

Authors: Tim Marshall (University of Manchester) , Katherine Morris (University of Manchester) , Gareth Law (Centre for Radiochemistry Research and Research Centre for Radwaste and Decommissioning, University of Manchester, U.K.) , Fred Mosselmans (Diamond Light Source) , Pieter Bots (University of Manchester) , Hannah Roberts (University of Manchester) , Sam Shaw (University of Manchester)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Mineralogical Magazine , VOL 79 , PAGES 1265 - 1274

State: Published (Approved)
Published: December 2015
Diamond Proposal Number(s): 7367 , 7593 , 8070

Open Access Open Access

Abstract: Uranium incorporation into magnetite and its behaviour during subsequent oxidation has been investigated at high pH to determine the uranium retention mechanism(s) on formation and oxidative perturbation of magnetite in systems relevant to radioactive waste disposal. Ferrihydrite was exposed to U(VI)aq containing cement leachates (pH 10.5–13.1) and crystallization of magnetite was induced via addition of Fe(II)aq. A combination of XRD, chemical extraction and XAS techniques provided direct evidence that U(VI) was reduced and incorporated into the magnetite structure, possibly as U(V), with a significant fraction recalcitrant to oxidative remobilization. Immobilization of U(VI) by reduction and incorporation into magnetite at high pH, and with significant stability upon reoxidation, has clear and important implications for limiting uranium migration in geological disposal of radioactive wastes.

Journal Keywords: uranium, magnetite, incorporation, EXAFS, radioactive waste, geodisposa

Subject Areas: Environment, Energy


Instruments: B18-Core EXAFS

Added On: 09/01/2016 13:55

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