Uranium fate during crystallization of magnetite from ferrihydrite in conditions relevant to the disposal of radioactive waste
Uranium fate during crystallization of magnetite from ferrihydrite in conditions relevant to the disposal of radioactive waste
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DOI：
10.1180/minmag.2015.079.6.02
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发表时间：
2015-11
影响因子：
2.7
通讯作者：
T. Marshall;K. Morris;G. Law;F. Mosselmans;P. Bots;Hannah E. Roberts;S. Shaw
中科院分区：
文献类型：
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作者：
T. Marshall;K. Morris;G. Law;F. Mosselmans;P. Bots;Hannah E. Roberts;S. Shaw
本文研究了高pH条件下磁铁矿中铀的掺入及其氧化行为，以确定放射性废物处置系统中磁铁矿形成和氧化扰动的铀滞留机理。将铁石膏暴露于含有U（VI）aq的水泥浸出液（pH 10.5-13.1）中，并通过添加Fe（II）aq诱导磁铁矿结晶。XRD、化学萃取和XAS技术的组合提供了直接证据，表明U（VI）被还原并结合到磁铁矿结构中，可能作为U（V），其中显著部分为氧化再活化。在高pH值下通过还原和掺入磁铁矿固定U（VI），并在再氧化时具有显着的稳定性，对于限制放射性废物地质处置中的铀迁移具有明确和重要的意义。
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.