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

该奖项由化学部的环境化学科学计划支持。 圣路易斯华盛顿大学的丹尼尔·吉阿马尔和杰弗里·卡塔拉诺教授及其团队研究铀和铅，这是自然产生的有毒元素和重要的环境污染物。 铀和铅通常以氧化物（与氧结合）的形式存在于自然界中。铀和氧化铁在环境中的反应性取决于它们的氧化还原化学。这些物质的重结晶会影响其毒性。这项研究扩展了我们对铀和铅氧化物氧化还原驱动重结晶的发生和环境影响的理解。 这项工作建立在其他金属氧化物重结晶的相关研究基础上，特别是氧化铁（“锈”）和氧化锰。 通过该项目获得的科学知识可用于减少受污染地下水中的铀和受污染饮用水中的铅的接触。 该研究与教育活动相结合，涉及课程丰富，研究生培训，并推广到K-12学生和其他公众成员。该项目探讨了氧化还原驱动的重结晶作为许多半导体金属氧化物共同的环境意义的一般现象。 具体目标包括测量铀（VI）水溶液与固体铀（IV）氧化物之间以及铅（II）水溶液与固体铅（IV）氧化物之间同位素交换的速率和程度。再结晶对所得到的颗粒的组成、结构和尺寸的影响正在被表征。同位素交换和重结晶的条件下有关的修复铀污染的地下水和控制饮用水分配系统中的铅被用来量化重结晶对污染物的流动性的影响。

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.