Synergistic solvent extraction of trivalent americium and europium by 2-bromodecanoic acid and neutral nitrogen-containing reagents

The synergistic enhancement in the extraction of trivalent actinides (Am and Cm) and some lanthanides by 2-bromodecanoic acid and different nitrogen-containing extractants was studied. The extraction by mixtures of 2-bromodecanoic acid and 2,2':6',2 "-terpyridine or N,N'-dimethyl-N,N'-dicyclohexyltetradecyl malonamide (DMDCHTDMA) respectively, in tert-butylbenzene (TBB) or hydrogenated tetrapropene (TPH), was investigated and compared with 2,4,6-tri-(2-pyridyl)-1,3,5-triazine (TPTZ) in synergy with 2-bromodecanoic acid. The synergistic enhancement and the separation factor between americium and europium was higher with the terpyridine mixture compared with the malonamide mixture. The separation factor between americium and europium from nitric acid (0.01 M) with terpyridine (0.02 M), 2-bromodecanoic acid (1 M) in TBB was determined to be 7, while the separation factor for malonamide (0.1 M), 2-bromodecanoic acid (1 M) in TBB was approximately 3. This might indicate a more covalent character in the actinide-terpyridine complex than in the actinide-malonamide complex. The terpyridine was shown to be easily transferred to the aqueous phase when protonated and thus the protonation ability for terpyridine was investigated at different concentrations of terpyridine and 2-bromodecanoic acid. Studies to determine the stoichiometry of the M(III) extracted complex with the synergistic mixtures were also performed.