In many application areas there is often a need for fit-for-purpose and efficient separation strategies. This is even more important when looking for nuclear waste management solutions where the materials challenges are just one aspect. Holistic assessments including; materials creation, through to application, through to waste disposal, all play a role in informing practical solutions for the extreme environments encountered.
Our research has focused upon the synthesis of novel hierarchical bead materials optimized for selective separations. In line with holistic nuclear waste treatment, the sorbent materials are fabricated with base media that could also potentially be used, post-adsorption, for waste immobilization or as transmutation matrices. To impart selectivity into the sorbents the work has been based upon incorporating extractants, currently used in solvent extraction processes, into solid-phase materials.
Materials for separations in a nuclear context must also be assessed for their chemical stability, including both hydrolytic and radiolytic stability. Group IV metal oxide and phosphonate based materials can impart superior hydrolytic and radiolytic stability and as such are the foundation of much of this work.
Finally, using hierarchical structured beads of separation materials provide significant advantages when implemented in practice. A hierarchical bead structure is desirable as it allows ease of handling and close packing in chromatographic columns. There is also a volume and waste by-product advantage of solid-liquid separation when compared to the more conventional liquid-liquid separation processes. It has also been demonstrated that hierarchical bead morphologies provide greater availability of functional surface with the same selectivity, higher extraction loading, and the advantage of improved kinetics.