Title  Electrochemical Separation of Curium and Americium	Researchers D. Hatchett, K. Czerwinski Collaborators George F. Vandergrift, III, Senior Scientist, Chemical Technology Division, Argonne National Laboratory
Background  In the Transmutation Research Program the separation of the trivalent actinides Am and Cm from the trivalent lanthanides, and even each other, has been identified as an area of particular interest.  The removal of lanthanides from trivalent actinides is necessitated for the neutron economy of a fuel containing Am and Cm.  Furthermore, a fuel containing only Am would ease the demands on a reactor for transmutation.  The destruction rate of Cm isotopes in a reactor is comparable to their decay rate.  Separation and storage of the Cm, and reintroduction into the fuel of the Pu daughters, is a transmutation option that can be explored if a suitable method for the separation of Cm from Am is obtained.  Furthermore, removal of Cm would reduce difficulties in fuel fabrication.  Electrochemical methods can be used to effectively separate actinide and lanthanide species from complex mixtures.  This is based on the unique electrochemical properties of each specific target species.  In studies it has been found that with the exception of Ce, aqueous solutions provide unsuitable electrochemical windows to effectively evaluate the thermodynamic properties that are useful for chemical separation.  Therefore a more novel approach was examined which eliminated the aqueous solution with a Room Temperature Ionic Liquid (RTIL) solution.  RTIL solutions do not suffer from the side reactions that are prominent in aqueous environments.  In addition the potential window is much larger for the RTIL solutions.  The RTIL solutions are a new starting point for the electrochemical separation of individual species from a mixture.	Research Objectives and Methods The objectives of this project are to use electrochemical techniques techniques to develop a thermodynamic understanding of actinide and lanthanide species in RTIL solution, and to use this data to effectively separate species with very similar chemical properties.  In consultation with a national laboratory collaborator, electrochemical methods and materials will be evaluated and used to exploit the thermodynamic differences between similar chemical species, enhancing the ability to selectively target and sequester individual species from mixtures.  This project is in its third year and has successfully completed phases 1 and 2.  Phase 3 has been partially completed.  The tasks have been expanded to include a fourth phase.  Phase 1 Evaluate thermodynamic oxidation/reduction properties of Ce using electrochemical methods.  Phase 2 Evaluate the thermodynamic properties of chelated Ce, Sm, and Eu at carbon, platinum and gold electrodes.    Phase 3 Examine the use of conductive polymer membranes for the uptake and expulsion of complexed and uncomplexed actinide and lanthanide species.  This phase still needs to examine the uptake, selective adsorption and separation of individual actinide and lanthanide species, including the isolation of Cm from Am, using conductive polymer/metal composite membranes containing bound chelates.  Phase 4 Prepare and characterize RTIL solutions.  Examine the electrochemical window and evaluate the electrochemical properties of lanthanide and actinide species in the non-aqueous ionic environment.  The following were specific goals for this year: Electrochemistry of GC, Au, and Pt electrodes in RTIL ([MeBu3N][NTf2]) (red) and 0.1 M H2SO4 (blue).   The IR spectra show the typical RTIL anion Li(TFSI) (blue), and UO2 complexed to TFSI (red).  The shift of the SO2 peak at 1350cm-1 indicates TFSI complexation, and the peak around  810cm-1 indicates the presence of a U=O bond.
Students  Sandra Elkouz G Wendy Pemberton G	Department Mechanical Engineering
Final Report	Annual Report
Proposal 05/07/04	Quarterly Reports   10/01/04-12/31/04   01/01/05-03/31/05  04/01/05-06/30/05  01/01/06-03/31/06