Basic studies about CMPO, Diamide comparison; Properties of Ln(III) extraction and behavior of third phase formation

Shibata, Atsuhiro  ; P.Y.COR*; not registered; not registered; not registered; not registered; Tanaka, Yasumasa

PNC has developed the TRUEX process to recover transuranium elements from high level liquid waste. This process uses CMPO as extracting solvent. DIAMEX process which uses Diamide has been developed bY CEA in France. The aim of basic studies was to get some comparison data between CMPO and Diamide. We have conducted the experiments regarding properties of Ln(III) extraction and behavior of third phase formation. Also, we have investigated properties of Ln(III) extraction with TBP and DBBP to compare bidentate ligand with monodentate ligand. This study was conducted as a frame of PNC/CEA collaboration on minor Actinide partitioning. The conclusions drawn from our studies can be summarized as follows; (1)Trivalent Lanthanides extraction reaction. CMPO, TBP and DBBP ; Ln + 3NO + 3Extractant Ln(NO) 3Extractant. Diamide; Ln + 3NO + m Diamide Ln(NO) m Diamide : m=O.71.8. (2)Extraction equilibrium constant. Apparent extraction equilibrium constants were calculated from the trivalent Lanthanides extraction reaction. The value of the constants were CMPO Diamide DBBP TBP.CMPO has high extraction efficiency for trivalent metals such as Am, but the back extraction is difficult in nitric acid media. Diamide indicated better behavior about both extraction and back extraction. (3)Separation Factors. We got separation factors (SFs) for intra-group in nitric acid. So SFs for CMPO and Diamide were nearly one, that these solvents could not separate each Lanthanides elements. The other hand, SFs for TBP and DBBP were 2 10. (4)Behavior of third phase formation. When using CMPO or Diamide, even in the case of extraction of nitric acid, third phase formation was found. When third phase was formed, the nitric acid concentration in aqueous phase was 6 N for CMPO, 4 N for Diamide. If Diamide diluted with Decaline was used, third phase wasn't found ...