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The complexation of Cm(III) and Eu(III) with the novel i-SANEX complexing agent 2,6-bis[1-(propan-1-ol)-1,2,3-triazol-4-yl]pyridine (PTD) was studied by time-resolved laser fluorescence spectroscopy (TRLFS). The formation of 1:3, 1:2, and 1:1 metal/ligand complexes was identified upon increasing PTD concentration in 10 mol/L HClO and in 0.44 mol/L HNO solutions. For all these complexes, stability constants were determined at different acid concentrations. Though under the extraction conditions proposed for an An/Ln separation process, that is, for 0.08 mol/L PTD in 0.44 mol/L HNO, 1:3 complexes represent the major species, a significant fraction of 1:2 complexes was found. This is caused by ligand protonation, and results in lower Eu(III)/Am(III) separation factors compared to SO-Ph-BTP, until now considered the i-SANEX reference ligand. Focused extraction studies performed at lower proton concentration, where the 1:3 complex is formed exclusively, confirm this assumption.

Four lipophilic 1,10-phenanthroline di(thio)amide, diester or diketone derivatives were studied as ligands for Am(III)/Eu(III) separation from acidic media. The synthesis of these compounds is reported together with the extraction tests in different solvents (kerosene, octanol and o-nitrophenyl hexyl ether), HNO3 concentrations and ratios between the ligand and the synergistic agent (Br-Cosan). The promising results obtained from the large number of solvent extraction tests carried out show that it might be possible to apply this class of ligands to advanced reprocessing of spent nuclear fuel. The experimental data indicate that, under the conditions that simulate the real radioactive waste, the extraction efficiency and Am/Eu separation factors are particularly high, thus suggesting that the combination of soft heterocyclic N-donor atoms and hard carbonyl groups of ester and amides affords a tetradentate donor set of atoms (ONNO) that gives rise to remarkable selectivities. ESI-MS studies and DFT calculations shed light on the possible structure of the Eu(3+) complexes indicating that the 1 : 1 : 2 (cation : ligand : anion) complex is slightly more stable than the 1 : 2 : 1 species.

he adsorption of uranium (VI), cesium and strontium ions from aqueous solutions onto a commercial activated carbon obtained by physical activation of coconut shell has been studied in batch systems. In particular the adsorption of uranium, studied as a function of contact time and metal ion concentration, followed pseudo-first-order kinetics. Equilibrium adsorption data were fitted by Langmuir and Freundlich isotherm models and the maximum adsorption capacity of the activated carbon resulted to be 55.32 mg/g. The study showed that the considered activated carbon could be successfully used for uranium adsorption from aqueous solutions. Feasibility of cesium and strontium adsorption onto the same activated carbon has been also investigated. Results showed that no affinities with both of these ions exist