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Comprehensive study has been performed on the extraction of actinide ions of various oxidation states, An n + (An=U, Np, Pu, Am, Cm and Cf), with bis(1-phenyl-3-methyl-4-acylpyrazol-5-one) derivatives, H 2 BP n ( n ; number of polymethylene chain=3, 4, 5, 6, 7, 8, 10 and 22). All H 2 BP n derivatives showed higher extraction efficiencies for An n + than 1-phenyl-3-methyl-4-benzoylpyrazol-5-one (HPMBP) did, which is attributable to the strong multidentate interaction with An n + or high hydrophobicity of H 2 BP n in comparison with HPMBP. The highest efficiency for all An n + examined was obtained with H 2 BP8 or H 2 BP7. The extracted species were confirmed as An(BP n )(HBP n ) for Am 3+ , Cm 3+ and Cf 3+ , and An(BP n ) 2 for U 4+ , Np 4+ and Pu 4+ . The extracted species of UO 2 2+ depended on the length of the polymethylene chain. The species UO 2 (HBP n ) 2 was extracted with H 2 BP3 or H 2 BP4 and UO 2 (BP n ) with H 2 BP n of n ≥5. NpO 2 + was hardly extracted from the solution of pH less than 9. On the basis of the correlation between the distribution ratio and pH the procedure for the successive separation of the actinides in nitric acid medium was developed. The recommended procedure using H 2 BP8 was applied to the mutual separation of UO 2 2+ , NpO 2 + , Pu 4+ and trivalent transplutonium ions. |
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