The objective of this program is to design, synthesize, and evaluate high-efficiency, high-capacity sorbent materials capable of selectively sequestering actinides from complex aqueous mixtures. One of the central goals of this project is to understand the fundamental interfacial science required to develop novel mesoporous materials coated with organized monolayers of rationally designed ligands, custom-tailored for binding specific actinide cations. This capability addresses waste management by separation of actinides, a central concern of high-level waste (HLW) management at several DOE sites. PNNL has developed self-assembled monolayers on mesoporous supports (SAMMS) as a superior method of mercury and heavy metal sequestration. SAMMS has proven to be orders of magnitude faster and more effective than existing mercury-scavenging methods. This project builds on the SAMMS concept and extends the interfacial chemistry of monolayer-coated mesoporous materials to study the requirements of selective binding of actinides. The need exists in the management of DOE's HLW to be able to selectively and completely remove the actinides so that HLW volume can be minimized and the nonradioactive components can be segregated and disposed of as low-level waste (LLW). In addition, the short-term risk assessment for tank closure requires a complete and accurate accounting of actinide speciation. These needs dictate the development of selective and efficient separation of actinides from complex waste streams so as to minimize HLW volume, reduce waste management costs, and enhance long-term stability of the HLW form.
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