An atomic scale computational approach to understanding REDOX speciation of uranium on iron bearing minerals

拟议的PHD研究将使用最先进的量子化学计算和正在进行的实验研究，以确定铀与含铁矿物的氧化还原形态，包括从铀酰(VI)还原为铀酰(V)、铀(IV)以及以NDA地点存在的氧化还原活性矿物为代表的Fe(II)氧化还原活性矿物的歧化机理。结果将明确支持土地质量专题领域(NDA助学金C5部分)。具体目标是：1.利用量子化学计算(密度泛函理论)研究铀酰(VI)-Fe(II)矿物相互作用，并辅之以实验拉曼光谱、光学光谱和X射线吸收光谱数据。2.寻找含铁(II)矿物麦金纳威石、铁水铁矿、磁铁矿和黄铁矿。3.允许准确预测热力学参数和光谱数据(氧化还原电位、EXAFS、拉曼光谱、红外光谱和光谱)，将其输入到ANDRA特定相互作用理论数据库和PHREEQC等地球化学模型中。4.研究了铀酰(V)与Fe(II)矿物表面的相互作用机理。5.进一步检查生成的还原/氧化物种，包括导致铀酰(V)歧化、重整铀酰(VI)和产生U(IV)相的关键低聚铀(V)聚集体。6.建立吸附和解吸的热力学参数，包括铀酰(VI)和(V)阳离子接近给定矿物表面或晶面的能量分布。

The proposed PhD research will use state of the art quantum chemical calculations and accompanying ongoing experimental studies to determinethe REDOX speciation of uranium with iron-bearing minerals, including reduction from uranyl(VI) to uranyl(V), U(IV) and disproportionationmechanisms on Fe(II) REDOX active minerals representative of those present at NDA sites. Outcomes will explicitly support the Land Qualitythematic area (NDA bursary call section C5). The specific objectives are to: 1. Employ quantum chemical calculations (density functional theory) toinvestigate uranyl(VI)-Fe(II) mineral interactions, complemented by experimental Raman, optical and X-ray absorption spectroscopy data. 2. Targetthe Fe(II) bearing minerals mackinawite, ferrihydrite, magnetite and pyrite. 3. Allow accurate prediction of the thermodynamic parameters andspectroscopic data (REDOX potentials, EXAFS, Raman, IR and optical spectra) to feed into geochemical models e.g. the ANDRA Specific InteractionTheory database and PHREEQC. 4. Investigate the mechanisms of uranyl(V) interaction with Fe(II) mineral surfaces. 5. Further examine the resultantreduced/oxidised species including key oligiomeric uranyl(V) aggregates that lead to disproportionation of uranyl(V), reforming uranyl(VI) andproducing U(IV) phases. 6. Establish thermodynamic parameters for sorption and desorption, including the energy profiles for approach of uranyl(VI)and (V) cations to a given mineral surface or crystallographic plane.