Application of synergistic MEHPA-DEHPA mixed solvent to the extraction of lanthanides(III)

The distribution ratio of neodymium(III) in extraction with mono(2-ethylhexyl)-phosphoric acid was determined as a function of extractant and Nd(III) concentrations, and effect of co-existing DEHPA was studied. A characteristic extraction of a tracer quantity of Nd(III) was found at an extractant concentration of approximately 0.01 M. Di(2-ethylhexyl)phosphoric acid depresses the extraction of Nd(III) in MEHPA of a concentration of 0.01M, but enhances it at higher concentrations of MEHPA. Owing to the high Df values against lanthanides(III) and an excellent radiation stability, the synergistic combination of MEHPA-DEHPA, preferably at a DEHPA/MEHPA mole ratio of 3, was concluded to be applicable to the isolation of lanthanides (and actinides) from highly acidic solutions.