EXTRACTION OF PLUTONIUM(IV) WITH 1-PHENYL-3-METHYL-4-BENZOYL PYRAZOL-5-ONE AND TRI-N-OCTYLPHOSPHINE OXIDE

The synergistic extraction of plutonium(IV) with 1-phenyl-3-methyl-4-benzoyl pyrazol-5-one (HPMBP) and tri-n-octylphosphine oxide (TOPO) has been investigated using toluene as the diluent and perchloric acid as the aqueous medium. Several species with the stoichiometry Pu(PMBP)4, Pu(PMBP)4 . TOPO and Pu(PMBP)3(ClO4) . 2TOPO are co-extracted into the organic phase. The relative proportion of these species depends on the perchlorate concentration and on the concentration ratio of HPMBP to TOPO. The adduct formation constants for the ternary species for Pu4+ are found to be smaller than those of UO22+ and Am3+. Steric factors play a dominant role in the coordination of the neutral oxodonor.