Thermodynamic study of Am(III) and Eu(III) extraction by iso-butyl-bis-triazinyl-pyridine

摘要

In order to better understand the extraction mechanisms of An(III) and Ln(III) by bis-triazinyl-pyridines (Btp), as well as the affinity of the latter towards An(III), the extraction of ~(152)Eu and ~(241)Am by 2,6-bis(5,6-iso-butyl-1,2,4-triazin-3-yl)-pyridine (iBu-Btp) was deeply studied. The distribution ratios (D_M) of both radiotracers were determined by γ spectrometry. The analyses of the slopes of "log-log" plots of experimental D_m values vs the concentration of iBu-Btp or that of nitrate anions at equilibrium, allowed the stoichiometry of the extracted complexes to be estimated. The extraction constants of Eu(III) and Am(III) were thereafter calculated at different temperatures and thermodynamic data, such as ΔH_(ex) and ΔS_(ex), were deduced from the Van't Hoff's law.