Plutonium Interactions with Ethylenediaminetetraacetic Acid: Solubility, Redox Behavior, and the Influence of Aqueous Calcium and Iron Oxide Minerals

This dissertation explores the behavior of plutonium in the presence of ethylenediaminetetraacetic acid (EDTA) under environmentally- and repository-relevant boundary conditions. There are two main research foci: (i) defining the binary interactions between plutonium and EDTA and (ii) probing the impact of major cations of environmental relevance (Ca(II), Fe(II/III)) on the interactions of plutonium and EDTA. The first area of research utilized undersaturation solubility studies, spectrophotometry, and advanced spectroscopic methods as a function of pH and time to investigate the speciation, solubility, and redox reactions in binary Pu-EDTA systems. The second area of research highlights the role of aqueous Ca(II) and iron oxide minerals within Pu-EDTA systems through the use of undersaturation solubility studies, advanced spectroscopic techniques, theoretical modeling efforts, and ternary sorption studies. The results of this dissertation indicate that the investigation of binary systems is not enough to develop a comprehensive understanding of the fate and transport of plutonium; the interplay between different environmental interactions can significantly impact the long-term mobility of plutonium in environmental settings and must be understood to further waste disposal and remediation/containment efforts.