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An americium(III) selective separation procedure was developed based on the co-extraction of trivalent actinides (An(III)) and lanthanides (Ln(III)) by TODGA (N,N,N',N'-tetraoctyldiglycolamide), followed by Am(III) selective stripping using the hydrophilic complexing agent 3',3'',2,5,6,tetrayl]tetrabenzenesulfonic acid). Distribution ratios were found at an acidity of 0.65 mol L -1 nitric acid that allowed for the separation of Am(III) from Cm(III) (D Cm > 1, D Am < 1), giving a separation factor between curium and americium of SF Cm/Am = 3.6 within the stripping step. The formation of the 1:1 complex was suppressed in 0.5 mol L -1 nitric acid but it was significantly present in HClO 4 at pH 3. Conditional stability constants of the complex species were calculated from the TRLFS experiments.

The applicability of 2,6-bis[1-(propan-1-ol)-1,2,3-triazol-4-yl)]pyridine (PyTri-Diol) in i-SANEX process as water-soluble complexing agent was studied. Preliminary batch experiments were aimed at identifying the optimal formulation of the PyTri-Diol solution and at preparing the ground for single-stage centrifugal contactor experiments. A TODGA-based solvent loaded using a spiked synthetic PUREX raffinate and the optimized PyTri-Diol aqueous phase were contacted in a single-stage annular centrifugal contactor setup with three different flow-rate conditions. No hydrodynamic problems were encountered and promising minor actinides separation from other cations was achieved with satisfactory kinetics and stage efficiency. The flow-sheet of a TODGA-PyTri-Diol based i-SANEX process was designed exploiting batch and single-stage data, promoting the CHON compliant PyTri-Diol as excellent alternative to the formerly used SO 3-Ph-BTP.

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Previous studies have identified the TPAEN ligand as a potentially appropriate complexing agent in solvent extraction processes for the separation of americium (Am(III)) from the fission products including lanthanide (Ln(III)) and curium (Cm(III)) ions, a challenging issue for advanced nuclear fuel recycling. To get insight into the selectivity of this ligand, the complexation of selected trivalent Ln(III) and actinide (An(III)) cations with TPAEN was investigated in solution. First, the structure and stoichiometry of the TPAEN complex with Am(III) were characterized by extended X-ray absorption fine structure spectroscopy (EXAFS). Then complexation constants and thermodynamics data were acquired for the complexes using different methods: microcalorimetry for the Ln(III) cations, time-resolved laser fluorescence spectroscopy (TRLFS) for Eu(III) and Cm(III), and UV-visible spectroscopy for Nd(III) and Am(III).