Extraction of micro- and macroconcentrations of rare earth ions with the mixture of D2EHPA and TBP in n-hexane and cyclohexane

The synergistic solvent extraction of Eu(III) and some other rare earth elements from nitrate solutions (HNO3+LiNO3) by a mixture of (TBP+D2EHPA) in n-hexane and cyclohexane has been investigated at 22 °C. Antagonism found in europium extraction from 0.1M HNO3 transforms into a synergistic effect. The synergistic effects existing for all investigated metals in extraction from 0.1M HNO3+3M LiNO3 were caused by formation of mixed complexes of the type Ln(D2EHPA)2nH2n−3+1(NO3)1TBPm, where 1=1 or 2. The selectivity of the extraction in a synergistic system is lower for the La−Yb pair than in the case of D2EHPA extraction under the same conditions. On the other hand, the application of the synergistic mixture is more suitable for Eu−Ho separation. Thus the synergistic effect can be used for the separation or refining of some lanthanides.