Extraction behavior of Pu(IV), Th(IV), and fission product elements with hexapropyl and hexabutyl phosphoramides

Hexapropyl phosphoramide (HPPA) and hexabutyl phosphoramide (HBPA) were examined for the macrolevel extraction and stripping of tetravalent metal ions such as Pu(IV) and Th(IV). The solvation number of Pu(IV) with both the phosphoramides were measured. The number of stages was evaluated for the quantitative extraction and stripping of Pu(IV) and Th(IV) in cross-current mode with 1.1 M phosphoramides in xylene from the nitric acid medium. The distribution ratios for the extraction of Th(IV) were measured with 1.1 M phosphoramides in xylene as a function of equilibrium aqueous phase Th(IV) and nitric acid concentration. In addition, distribution ratios for the extraction of fission product elements such as Zr, Tc, Ru, lanthanides (La, Pr, Nd and Gd) and activation product Am were also measured with 1.1 M HPPA and HBPA in n-Dodecane (n-DD) system as a function of aqueous phase nitric acid concentration. The extraction data generated with phosphoramides were compared with a 1.1 M TBP/n-DD system.

Effects of temperature on the extraction of U(VI) and Pu(IV) by tris(2-methylbutyl) phosphate from nitric acid media

Extraction behavior of tris(2-methylbutyl) phosphate (T2MBP), a higher homologue of tri-n-butyl phosphate (TBP), in the extraction of U(VI) and Pu(IV) from nitric acid media has been evaluated in the present study. Distribution ratios for the extraction of these metal ions by T2MBP were measured as a function of equilibrium aqueous phase nitric acid concentration, extractant concentration and temperature to understand the temperature effects on extraction. Enthalpies of extraction of T2MBP/n-dodecane-U(VI)-HNO3and T2MBP/n-dodecane-Pu(IV)-HNO3systems were calculated from the distribution ratio data using “second law” method. The data reveal that the extraction of U(VI) by T2MBP is exothermic in nature, whereas that of Pu(IV) is endothermic.

N,N,N′,N′-Tetra-Methyl-3-Oxy-Pentane-1,5-Diamide (TMPDA): A Promising Back Extractant for Ln(III) and Zr(IV)

Water-soluble oxa-diamide ligand, N,N,N′,N′-tetra-methyl-3-oxy-pentane-1,5-diamid (TMPDA) has been synthesized and purified. Its crystal structure, melting point, decomposition temperature, solubilities in aqueous phase and organic phase, distribution ratio between aqueous and organic phase, etc. are reported. The effect of TMPDA concentration in aqueous phase and HNO3 concentration in the equilibrium aqueous phase on the extraction efficiency of La(III), Ce(III), Pr(III), Nd(III), Zr(IV), Fe(III), Y(III), Mo(VI), Ru(III) and Pd(II) by 30% TRPO/kerosene have been studied. The results indicate that TMPDA dissolve well in aqueous phase but almost insoluble in kerosene or 30%TRPO/kerosene in the bi-phase system. It can effectively reduce the extraction of Ln(III), Y(III) and Zr(IV) into 30%TRPO/kerosene at a moderate acid system (0.24mol/L∼0.27mol/L HNO3). TMPDA is a promising stripping agent for Ln(III), Y(III) and Zr(IV) from loaded TRPO.