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 an d Cm) and some lanthanides by 2-bromodecanoic acid and different nitrogen-c ontaining extractants was studied. The extraction by mixtures of 2-bromodec anoic acid and 2,2':6',2 "-terpyridine or N,N'-dimethyl-N,N'-dicyclohexylte tradecyl 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 an d europium was higher with the terpyridine mixture compared with the malona mide mixture. The separation factor between americium and europium from nit ric 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 indi cate a more covalent character in the actinide-terpyridine complex than in the actinide-malonamide complex. The terpyridine was shown to be easily tra nsferred to the aqueous phase when protonated and thus the protonation abil ity for terpyridine was investigated at different concentrations of terpyri dine and 2-bromodecanoic acid. Studies to determine the stoichiometry of th e M(III) extracted complex with the synergistic mixtures were also performe d.