Separation of americium(III) and europium(III) from nitrate medium using a binary mixture of cyanex-301 with n-donor ligands

Separation behavior of Am3+ and Eu3+ was studied from aqueous nitrate medium using the "soft-donor" Cyanex-301 (bis(2,4,4-trimethylpentyl) dithiophosphinic acid) in toluene as the extractant. The separation factor (S.F.=D-Am/D-Eu) value of 5000 (obtained with pure Cyanex-301) increased about eight times when a binary mixture of Cyanex-301 and N-donor ligands (such as 2,2'-bipyridyl (bipy) or 1,10-phenanthroline (phen)) was used as the extractant. The S.F. values of >40,000 are the highest reported to date. Nitrate ion played an important role in the separation behavior of the trivalent lanthanide and actinide ions. The extracted species, established by the slope analysis method, are Am(A)(3).B-o and Eu(A)(2)(X).B-o , respectively where A = deprotonated form of Cyanex-301, B = phen or bipy and X = NO3- .