SYNERGISTIC SOLVENT-EXTRACTION OF TRIVALENT LANTHANIDES AND ACTINIDESBY MIXTURES OF L-PHENYL-3-METHYL-4-ACETYL-PYRAZOLONE-5 AND NEUTRAL OXE-DONORS

The synergistic solvent extraction of trivalent lanthanides such as La , Eu and Lu, and a trivalent actinide, Am, has been studied by tracer techniques with mixtures of 1-phenyl-3-methyl-4-acetyl-pyrazolone-5 (H PMAP) and octyl(phenyl)-N,N-diisobutyl carbamoylmethyl phosphine oxide (CMPO) or bis-(2-ethylhexyl)sulphoxide (B2EHSO) in xylene. The result s indicate that these trivalent metal ions are extracted as M(PMAP)(3) with HPMAP alone, in the presence of CMPO as M(PMAP)(3) . CMPO, or in the presence of B2EHSO as M(PMAP)(3) . B2EHSO and M(PMAP)(3) . 2B2EHS O. The synergistic extraction constants of the above species are found to increase monotonically with decreasing ionic radii of these metal ions. Although addition of an adduct-forming reagent to the chelate sy stem can bring a decrease in the separation factor, it is notable that addition of B2EHSO improves the separation of the Eu-Lu pair. The the rmodynamic parameters for the extraction of Eu(III) with HPMAP alone a s well as with mixtures of one of the neutral oxo-donors CMPO or B2EHS O in xylene have also been calculated at 25 degrees C using the temper ature coefficient method.