Radiolytic effects on actinide(III) complexation with a hydrophilic PyTri ligand

The selective Am and Cm recovery from the highly active raffinate could be achieved by innovative-Selective ActiNide EXtraction (i-SANEX) process downstream major actinides removal. The TetraOctyl-DiGlycolAmide (TODGA) extractant and a hydrophilic complexing agent, 2,6-bis[1-(propan-1-ol)-1,2,3-triazol-4-yl)]pyridine (PTD) being the most promising one, could be synergically used to separate Am and Cm from chemically similar lanthanides. Besides promising selectivity and efficiency for Am and Cm extraction, such systems must prove radiolytic and hydrolytic stability, given the high radionuclide content of the feed. In this work, PTD selectivity for trivalent Am and Cm towards Eu, chosen as representative lanthanides, has been studied at relevant conditions by different spectroscopic techniques. In order to mimic the process conditions, solutions of PTD were γ-irradiated up to 200 kGy by a 60Co source or aged up to 100 days in 0.44 mol/L HNO3 before complexometric titration experiments. The obtained UV-Vis and Time-Resolved Laser Fluorescence Spectroscopy (TRLFS) results were compared with those of fresh PTD solutions, in order to evaluate the impact of radiolysis and hydrolysis on metal-ligand complex formation. In accordance with the stability outlined by previous studies, also the complexation capabilities resulted to be unaltered. These results further support PTD as a valid candidate for partitioning processes.