Due to their many unique properties, using ionic liquids (ILs) as diluents for nuclear separations has numerous advantages, but also significant disadvantages (such as the higher costs, lower fluidity, unclear disposal pathways, and the general unfamiliarity of ILs to chemical technologists). In the minds of nonacademic separations scientists these disadvantages often eclipse the advantages since modest performance benefits do not justify a radical departure from the convention. Molecular diluents have been in use for 60+ years, and it is difficult to run against a vast backlog of hands-on technological experience. Thus, the use of ILs in nuclear separations requires very significant offsetting cost benefits and performance gains as compared with the molecular liquids. This confines ILs to a few niches, where their advantages can potentially exceed their disadvantages. It also follows that in addition to the widely known benefits of ILs, these diluents may have the less known ones that can tip the equation. I will teach that radiation stability of such IL diluents and their ability to inhibit radiation damage to the extractant can be regarded as such offsetting advantages. I will argue that one of the most challenging nuclear separations, viz. group separations of lanthanides from minor actinides, is conducive to IL adaptation, and I will demonstrate two ways of accomplishing this task, one which relies on “reinvention” of TALSPEAK and the other that relies on the use of task-specific soft-N-hard-O donors. A case will be made that extended cycle lifetimes due to radiation protection in these systems can become an argument in favor of further development of IL-based approaches.

Ionic liquids for separations of trivalent lanthanides and minor actinides: Combining performance and radiation stability

253rd National Meeting (2017)

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