MINOR ACTINIDE SEPARATIONS USING ION EXCHANGERS OR IONIC LIQUIDS

Hobbs, D. ; Visser, A. ; Bridges, N.

关键词: ACTINIDES;    AFFINITY;    ELECTROLYTES;    INORGANIC ION EXCHANGERS;    ION EXCHANGE;    ION EXCHANGE MATERIALS;    LIQUID ION EXCHANGERS;    MOLTEN SALTS;    OXIDATION;    OXIDIZERS;    PHOSPHONATES;    RARE EARTHS;    SODIUM;    TESTING;    TITANATES;    VALENCE;    WATER;    ZIRCONIUM;   

DOI  :  10.2172/1030792
RP-ID  :  SRNL-STI-2011-00554
PID  :  OSTI ID: 1030792
Others  :  TRN: US1200065

美国|英语

来源: SciTech Connect

【 摘 要 】

This project seeks to determine if (1) inorganic-based ion exchange materials or (2) electrochemical methods in ionic liquids can be exploited to provide effective Am and Cm separations. Specifically, we seek to understand the fundamental structural and chemical factors responsible for the selectivity of inorganic-based ion-exchange materials for actinide and lanthanide ions. Furthermore, we seek to determine whether ionic liquids can serve as the electrolyte that would enable formation of higher oxidation states of Am and other actinides. Experiments indicated that pH, presence of complexants and Am oxidation state exhibit significant influence on the uptake of actinides and lanthanides by layered sodium titanate and hybrid zirconium and tin phosphonate ion exchangers. The affinity of the ion exchangers increased with increasing pH. Greater selectivity among Ln(III) ions with sodium titanate materials occurs at a pH close to the isoelectric potential of the ion exchanger. The addition of DTPA decreased uptake of Am and Ln, whereas the addition of TPEN generally increases uptake of Am and Ln ions by sodium titanate. Testing confirmed two different methods for producing Am(IV) by oxidation of Am(III) in ionic liquids (ILs). Experimental results suggest that the unique coordination environment of ionic liquids inhibits the direct electrochemical oxidation of Am(III). The non-coordinating environment increases the oxidation potential to a higher value, while making it difficult to remove the inner coordination of water. Both confirmed cases of Am(IV) were from the in-situ formation of strong chemical oxidizers.