Recent events have called attention to the persistent possibilities of environmental and human contamination with radioisotopes such as lanthanide fission products and actinides. The challenge of limiting exposure to radionuclides and of establishing controlled industrial processes has given rise to unprecedented interest in developing specific lanthanide and actinide binding agents for separation and decontamination purposes. Separation of lanthanides and actinides is a challenging task due to the similarities in their ionic radii and the existence of most of these metal ions in the trivalent oxidation state. Our studies utilize luminescence sensitization and UV-Visible spectroscopic techniques to investigate the specific coordination of f-elements by hydroxypyridinonate hard oxygen-donor ligands. The solution thermodynamic properties of Ln(III), Cm(III), and Am(III) complexes formed with these strong chelating agents were investigated and leveraged to separate the different complexes using high performance liquid chromatography. Mass spectrometry and luminescence spectroscopy were then used to detect and identify the isolated species. While mostly soft donor ligands are used in actinide extraction processes, hydroxypyridinonate moieties have proven effective at separating the investigated trivalent ions. Moreover, the separation followed the lanthanide contraction over the f-shell, consistent with the measured complex stabilities. A predictive thermodynamic model was then devised to correlate the respective stabilities of other f-element complexes with coordination sphere properties and ligand separation potential.

Coordination, sensitization, and separation of trivalent lanthanide and actinide ions using hydroxypyridinonate hard donor ligands

247th National Meeting (2014)

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