TRIVALENT F-ELEMENT INTRAGROUP SEPARATION BY SOLVENT-EXTRACTION WITH CMPO-COMPLEXANT SYSTEM

For trivalent actimide and lanthanide separation, the solvent extracti on system which employs neutral bifunctional extractant tyl(phenyl)-N, N-diisobutylcarbamoylmethylphosphine oxide (CMPO) and aminopolyacetic acid was investigated. The system is based on CMPO-tri-n-butylphosphat e (TBP) mixed solvent and diethylenetriaminepentaacetic acid (DTPA)-so dium nitrate solution. The separation is achieved bq complexing trival ent actimide preferentially with DTPA in aqueous phase and extracting lanthanide into organic phase. Mutual separation between light lanthan ide, Am and Cm was mainly governed by complex formation with DTPA. The acidity is mast affecting parameter for partitioning and its increase results in decrease of distribution ratio. For selective stripping of trivalent actinide from 0.2 M CMPO-1.0 M TBP in n-dodecane at room te mperature, 0.05 M DTPA and 2-4 M sodium nitrate solution (pH 2) is use ful. From the observed distribution behavior, a basic flow sheet which is composed of four steps was proposed. In batchwise experiments with radioactive nuclides, separation factor of larger than 13 and 27 for Ce/Am and Cm/Eu, respectively, were obtained and the applicability of the system was indicated.