Faculty and Student Teams Program

Project Descriptions

Pacific Northwest National Laboratory
Radiochemical Science and Engineering Group

Project Title: Highly Selective Media for Actinide Collection and Pre-Concentration

Requesting applications from science or engineering faculty members at institutions serving students underrepresented in science, engineering, mathematics, and technology, to work on investigating highly selective media for actinide collection and pre-concentration.

Project Description

This work is a subset of a larger effort to develop automated radiochemical methods. Separation and pre-concentration of the desired analyte is often a critical step in radioanalytical methods. Current methods for separating and concentrating analytes for detection often involve complex wet chemical methods. The complexity of these separation schemes leads to relatively long sample preparation time, and automating such methods can be intricate. This is especially true for the separation of trivalent actinides. Sample preparation time and ease of automation can be greatly improved by using separation media that are highly specific for the analyte of interest. Over the past decade, researchers at PNNL have developed a ligand design methodology using computational methods to guide experimental work in separations chemistry. The deliberate design of metal ion receptors requires the capability to distinguish hosts that efficiently complement the guest. Accurate electronic-structure calculations can be coupled with experimental data to provide fundamental knowledge about host structure and the nature of ion-binding site interactions. With a molecular-level understanding of how host architecture influences ion-binding affinity, it is possible to identify structures that will provide dramatic enhancements in ion binding affinity before they are prepared and tested. The power of this approach was demonstrated at PNNL recently after a deliberately designed bicyclic diamide structure was found to extract Eu(III) ~16 million times more strongly than conventional malonamide structures.

Another class of actinide-selective ligands recently investigated at PNNL is the tripodal “Kläui ligands,” which have the general chemical structure Cp*Co[P(O)(OR)₂]₃^- [Cp* = η⁵-C₅(CH₃)₅, R = CH₃, C₂H₅, etc.]. We have observed high affinity of these ligands for the Pu(IV) ion. This presents an opportunity to apply these ligands in the collection and pre-concentration of Pu(IV). In a step towards practical application of the Kläui ligands, we prepared a prototypical resin containing the Kläui ligand where R = C₂H₅. Preliminary column experiments have indicated that this resin has remarkably high affinity for Pu(IV), even in the presence of large amounts of completing ions. The Pu(IV) affinity is maintained over a large range of acid concentrations (e.g., HCl concentrations up to 9 M and perhaps higher).

The work performed in this project will build upon these earlier studies at PNNL. In particular, bicyclic diamide and the Kläui ligands will be engineered into various separations media to allow for rapid collection and pre-concentration of Pu and other actinides. A number of engineered platforms will be considered, including attachment to functionalized organic resins, silica surfaces and magnetic nanoparticles. All of these options would allow for rapid and efficient concentrations of small amounts of analyte from a sample.

Applicants Responsibilities and Relationship to Project

Applicants will receive support under the Department of Energy Faculty Student Team Research Program (FaST) to work collaboratively with the project research team at the Pacific Northwest National Laboratory for up to 10 weeks during the year, starting in June 2006. Summer and academic year visits to PNNL will be scheduled by mutual agreement between the Radiochemical Science and Engineering Group and the successful applicant. Ideally, faculty will work at PNNL on the project for 10 weeks during the summer in the first year. Faculty will be expected to identify students from their campus to participate in the Undergraduate Research Participation programs offered by the Department of Energy at Pacific Northwest National Laboratory. Faculty will provide mentorship and/or advising support to students during the summer research activities. It is expected that the faculty member will become an integral part of the research team working on this project and will support the project through the academic year on her or his campus.

Qualifications of Ideal Candidate

Support and Financial Commitments

See Financial Information.

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