Separation Study of Am(III) and Eu(III) Using a Synergistic System of Cyanex-301 and 4,7-di-Phenyl-1,10-Phenanthroline

Separation of Am(III) and Eu(III) was attempted employing a mixture of Cyanex-301 and several O- and N- donor neutral ligands from low pH solutions. Out of these, the O-donor ligands displayed poor separation behavior at pH 2.0 as compared to those reported earlier at pH 3.5 which was ascribed to a change in the extraction mechanism. Out of the N-donor phenanthroline derivatives employed for the separation studies, 4,7-diphenyl-1,10-phenanthroline (Ph2Phen) displayed superior extraction behavior for Am(III) while not significantly extracting Eu(III). This resulted in a separation factor (S.F., defined as DAm/DEu) value of 9000 at pH 2.0 which is about four times lower that the S.F. value reported earlier at pH 3.5 using Phen as the neutral donor ligand. The methyl derivative, Me2Phen, showed remarkable poor extraction and separation behavior. Molecular modeling using ab initio calculations was used for explaining the unusual extraction behavior. The effect of sodium nitrate concentration on the separation behavior was also investigated.