Extraction studies of selected actinide ions from aqueous solutions with 4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione and tri-n-octylphosphine oxide.

摘要

The first measurements of distribution coefficients (K(sub d)) for Cm(III), Bk(III), Cf(III), Es(III), and Fm(III) between aqueous perchlorate solutions and solutions of 4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione (BMPPT) and the synergist tri-n-octylphosphine oxide (TOPO) in toluene are reported. Curium-243, berkelium-250, californium-249, einsteinium-254, and fermium-253 were used in these studies. The K(sub d) for (sup 241)Am was also measured and is in agreement with previously published results. Our new results show that the K(sub d)'s decrease gradually with increasing atomic number for the actinides with a dip at Cf. In general, the K(sub d)'s for these actinides are about a factor of 5 to 10 greater than the K(sub d)'s for the homologous lanthanides at a pH of 2.9, a BMPPT concentration of 0.2 M, and a TOPO concentration of 0.04 M. The larger K(sub d)'s for the actinides are consistent with greater covalent bonding between the actinide metal ion and the sulfur bonding site in the ligand.