2-Carboxamido-6-(1h-Pyrazol-3-Yl)-Pyridines As Ligands For Efficient Separation Of Americium(Iii) From Europium(Iii)

The synthesis, Eu3+ complexation, and selective solvent extraction of Am3+ over Eu3+ in nitric acid solution by 2-carboxamido-6-(1H-pyrazol-3-yl)-pyridines (A-PzPy) ligands were described. Without the aid of any lipophilic anion source, A-PzPy ligands in methyl isobutyl ketone (MIBK) diluent demonstrated a more favorable affinity of Am3+ than Eu3+ at high acidity levels. Slope analysis showed the formation of 1:2 metal/ligand extracted species. The extraction was a spontaneous exothermic process. The analyses of fluorescence titration, Fourier transform infrared (FT-IR), Raman, time-resolved laser fluorescence spectrum (TRLFS), electrospray ionization mass spectrometry (ESI-MS), conductivity and microcalorimetric titration revealed that the composition of complex is [Eu(NO3)(2)(H2O)center dot 2(Et-p-Tol-A-PzPy)](NO3). Combining the results of solvent extraction and complexation study, the extraction mechanism was proposed. Furthermore, the stability constants (log beta) and thermodynamic parameters (Delta H, Delta S, Delta G) for complexation of Eu3+ with Et-p-Tol-A-PzPy were also presented.