CAREER: Polymeric ligands with tunable affinities to enable selective f-element separations

The f-elements (lanthanides and actinides) play a crucial role in several peaceful applications of nuclear technology, including electricity generation, clean energy technologies, and cancer treatment. These elements can be harvested from natural resources through traditional mining approaches or by processing industrial waste sources. In many cases, the lanthanides must be separated from the actinides, like uranium and thorium, before they can be used in the final application. Lanthanides and actinides are currently separated by solvent extraction approaches - a chemical process with large physical and carbon footprints and also generates mixed radioactive waste. Membrane-based separations are an alternative to solvent extraction that can have a smaller physical footprint and minimize the volume of waste generated. Thus, designing membrane materials that can selectively achieve these separations is a key step in improving the sustainability and cost-effectiveness of these processes. The fundamental knowledge generated in this project will guide the design of future membranes that will be used in lanthanide/actinide separations from various feedstocks. The ability to selectively separate lanthanides from actinides via membranes will enhance national security and improve the efficiency of resource recovery and water treatment. This research program is integrated with an educational program that will develop service-learning opportunities for graduate students, engage the local Cleveland community through nuclear-focused outreach activities, and build a training program for future STEM educators focusing on inclusive teaching strategies. The goal of this research is to understand the molecular-level phenomena that underpin ion-ion selectivity in copolymer ligands used for f-element separations. This goal will be achieved by synthesizing polymer ligands with controlled compositions to serve as a platform for studying ligand-ligand and ligand-ion interactions. Molecular interactions will be investigated through a combined approach of computational modeling and spectroscopy. Finally, the polymer ligands will be coated on membrane surfaces. These studies will reveal the practical implications of intermolecular interactions on affinity, kinetics, and selectivity. This research will be integrated with a graduate-level radiochemistry course in which students will develop teaching tools to communicate radiochemistry concepts to non-scientific audiences. These tools will be deployed at outreach events that target K-12 students in Cleveland through partnerships with the Leonard Gelfand STEM Center and the Girl Scouts of Northeast Ohio. Finally, a new mentored-teaching experience for graduate students will serve as a practicum to integrate inclusive pedagogical techniques into their teaching portfolios. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.