Nuclear waste continues to accumulate without a long-term solution, significantly countering the benefits of nuclear energy. Nuclear waste is composed of many elements, and the most difficult to separate are the radioactive lanthanides and actinides. If the two could be separated, the total amount of nuclear waste would be decreased, and the partitioned lanthanides and actinides could be recycled (this is described as "closing the nuclear fuel cycle"). However, both lanthanides and actinides are primarily trivalent ions with very similar radii, leading to similar reactivity and difficult separations. The 5f orbital of the actinides is less shielded than the corresponding 4f orbital of the lanthanides, and this difference enables a greater degree of covalent interactions with softer ligands, such as sulfur and nitrogen. Previous lanthanide/actinide separation studies have utilized the principles of the TALSPEAK process, which exploits this difference in softness. A potential candidate for a similar TALSPEAK separation is N-(N'-(3-propyl)-N''-methylimidazole-2-thione) diethylenetriamine tetraacetic acid. This octadentate ligand can be synthesized by the nucleophilic substitution of diethanolamine by N-(3-bromopropyl)-N'-methylimidazolium bromide, followed by substitution by iminodiacetic acid moieties on the terminal amines to form N-(N'-(3-propyl)-N''-methylimidazolium bromide) diethylenetriamine tetraacetic acid. The imidazolium 2H can then be replaced by an S or Se under basic conditions. We will describe our work on this class of ligands and preliminary coordination chemistry studies with lanthanides.

Synthesis of N-(N'-(3-propyl)-N''-methylimidazole-2-thione) diethylenetriamine tetraacetic acid for the reduction of nuclear waste

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.