Synergistic Solvent Extraction of Trivalent Lanthanides and Actinides by Mixtures of l-Phenyl-3-methyl-4-acetyl-pyrazolone-5 and Neutral Oxo-Donors

Abstract

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 l-phenyl-3-methyl-4-acetyl-pyrazolone-5 (HPMAP) and octyl(phenyl)-N,N-diisobutyl carbamoylmethyl phosphine oxide (CMPO) or bis-(2-ethylhexyl)sulphoxide (B2EHSO) in xylene. The results 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 · 2B2EHSO. 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 system can bring a decrease in the separation factor, it is notable that addition of B2EHSO improves the separation of the Eu-Lu pair. The thermodynamic parameters for the extraction of Eu(III) with HPMAP alone as well as with mixtures of one of the neutral oxo-donors CMPO or B2EHSO in xylene have also been calculated at 25° C using the temperature coefficient method.