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

Timothy A. Marshall, Katherine Morris, Gareth T.W. Law, Frederick W. Mosselmans, Pieter Bots, Hannah Roberts, Samuel Shaw

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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. © 2016 by Walter de Gruyter Berlin/Boston.
Original languageEnglish
Pages (from-to)1265-1274
Number of pages10
JournalMineralogical Magazine
Volume79
Issue number6
DOIs
Publication statusPublished - 1 Dec 2015

Keywords

  • EXAFS
  • geodisposal
  • uranium incorporation
  • magnetite
  • radioactive waste
  • uranium
  • uranium retention mechanisms
  • uranium migration

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  • Projects

    BIGRAD AP13

    Morris, K., Shaw, S., Bots, P., Law, G., Marshall, T. A. & Mosselmans, J. F. W.

    25/05/1326/04/14

    Project: Research

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