Impact of Redox-driven Recrystallization on the Stability and Reactivity of Uranium and Lead Oxides

该奖项是由化学部门的环境化学科学项目支持的。华盛顿大学圣路易斯分校的丹尼尔·贾马尔教授和杰弗里·卡塔拉诺教授及其团队研究铀和铅，这两种天然存在的有毒元素和重要的环境污染物。铀和铅通常以氧化物的形式存在于自然界中（与氧结合）。铀和铁的氧化物在环境中的反应性取决于它们的氧化还原（“氧化还原”）化学性质。这些物种的再结晶会影响它们的毒性。本研究扩展了我们对氧化还原驱动铀和铅氧化物重结晶的发生和环境影响的理解。这项工作建立在对其他金属氧化物，特别是氧化铁（“锈”）和锰氧化物的再结晶的相关研究的基础上。该项目获得的科学知识可用于减少受污染地下水中的铀暴露和受污染饮用水中的铅暴露。该研究与教育活动相结合，包括课程丰富，研究生培训，以及向K-12学生和其他公众成员推广。该项目探索氧化还原驱动的再结晶作为许多半导体金属氧化物共同具有环境意义的一般现象。具体目标包括测量水铀（VI）和固体铀（IV）氧化物之间以及水铅（II）和固体铅（IV）氧化物之间同位素交换的速率和程度。表征了再结晶对所得颗粒的组成、结构和尺寸的影响。与铀污染地下水的修复和饮用水分配系统中铅的控制有关的条件下的同位素交换和再结晶正在被用来量化再结晶对污染物迁移的影响。

This award is supported by the Chemistry Division's Environmental Chemical Sciences Program. Professors Daniel Giammar and Jeffrey Catalano and their groups at Washington University in St. Louis study uranium and lead, which are naturally-occurring, toxic elements and important environmental contaminants. Uranium and lead often exist in nature as oxides (bonded to oxygen). Uranium and iron oxide reactivity in the environment depend on their oxidation-reduction ("redox") chemistry. The recrystallization of these species can impact their toxicity. This study extends our understanding of the occurrence and environmental impacts of redox-driven recrystallization of uranium and lead oxides. The work builds on related studies of recrystallization of other metal oxides, notably iron oxides ("rust") and manganese oxides. The scientific knowledge gained by this project can be used to reduce exposure to uranium in contaminated groundwater and to lead in contaminated drinking water. The research is integrated with educational activities that involve curriculum enrichment, graduate student training, and outreach to K-12 students and other members of the public. The project explores redox-driven recrystallization as a general phenomenon of environmental significance common to many semiconducting metal oxides. Specific targets include measurements of the rates and the extent of isotope exchange between aqueous uranium (VI) and solid uranium (IV) oxides and between aqueous lead (II) and solid lead (IV) oxides. The impacts of recrystallization on the composition, structure and size of the resulting particles is being characterized. Isotope exchange and recrystallization under conditions relevant to remediation of uranium-contaminated groundwater and the control of lead in drinking water distribution systems are being used to quantify the impacts of recrystallization on contaminant mobility.