Search

N,N-Dialkyl diglycolamic acid (HDRDGA) derivatives with alkyl groups varying from n-hexyl to n-dodecyl were synthesized, and the promising ligands such as N,N-dioctyl diglycolamic acid (HDODGA) and N,N-didecyl diglycolamic acid (HD2DGA) were investigated for the mutual separation of trivalent lanthanides and actinides from dilute nitric acid solution. Since diglycolamic acid is strongly polar, it was dissolved in a traditional diluent, n-dodecane, with the help of an isodecyl alcohol (IDA) phase modifier. Nevertheless, the hexyl and didodecyl derivatives were sparingly soluble even in the presence of 30% (v/v) IDA in n-dodecane, and therefore, the extraction behavior of the lanthanide and actinide representatives, Eu(III) and Am(III), respectively, was studied only in a solution of HDODGA or HD2DGA present in 30% (v/v) IDA/n-dodecane. The cation-exchange mechanism of extraction and the stoichiometry of trivalent metal to HDRDGA were elucidated from the slope analysis of the extraction data. Since the stoichiometry of the metal to ligand complex in the organic phase was unusually varied from 1 : 3 to 1 : 6 depending upon the Nd(III) loading into the organic phase, the reverse micellar aggregation behavior and the coordination chemistry of Nd(III) in the organic phase were probed by dynamic light scattering and visible spectroscopy, respectively. The results revealed that three molecules of anionic DRDGA were coordinated to Nd(III) in the inner-sphere at lower metal concentrations, and also three more molecules of HDRDGA in the outer-sphere at higher metal concentrations. The good separation factor achieved with the use of these ligands showed their potential ability to separate lanthanides from actinides in nitric acid medium. [ABSTRACT FROM AUTHOR]

N,N-dihexyloctanamide (DHOA) is being considered as a promising extractant in the aqueous reprocessing of spent nuclear fuels. In view of rise in temperature of the solvent during reprocessing of fast reactor fuel, the present study aimed at evaluating the physical properties such as density, viscosity, and interfacial tension and Pu(IV) extraction behavior in 1.1 M DHOA/n-dodecane as a function of temperature and duration of heating. The influence of nitric acid in altering the physical properties with respect to temperature was evaluated. Physical properties and extraction behavior of the solvent changed to a remarkable extent with temperature. Quantitative amount of Pu(IV) could be back-extracted from loaded, solvent in three contacts at 313 K. FT-IR studies were carried out to evaluate the thermal stability of the solvent. Thus, the performance of the solvent, 1.1 M DHOA/n-dodecane is satisfactory at higher temperatures also. [ABSTRACT FROM AUTHOR]

Various diglycolamides (DGAs),N,N,N’,N’-tetraoctyl diglycolamide (TODGA),N,N-di-2-ethylhexyl-N’,N’-di-octyl diglycolamide (DEHDODGA),N,N,N’,N’-tetra-2-ethylhexyl diglycolamide (TEHDGA),N,N-di-decyl-N’,N’-di-hexyl diglycolamide (D2DHDGA),N,N-di-butyl-N’,N’-di-dodecyl diglycolamide (DBD3DGA),N,N,N’,N’-tetra-hexyl diglycolamide (THDGA), andN,N,N’,N’-tetradecyl diglycolamide (TDDGA) have been synthesized and studied for the extraction of Am(III) and Eu(III) from nitric acid medium. An attempt was made to understand the extraction and third phase formation behavior of trivalent metal ions in these DGAs. Our results revealed that despite having the same carbon to oxygen ratio in these DGAs, the third phase formation behavior and extractions achieved in these DGAs are significantly different. [ABSTRACT FROM AUTHOR]

The radiolytic degradation of N, N-di-dodecyl- N′, N′-di-2-ethylhexyl-3-oxapentane-1,5-diamide (DDEHDGA) was studied at various absorbed doses of γ-radiation. The degradation was assessed by measuring the variation in the extraction behavior of Am(III) in irradiated solvent systems composed of neat DDEHDGA or 0.1 M DDEHDGA/ n-dodecane in the presence and absence of nitric acid. The distribution ratio of americium ( D) decreased with increase of absorbed dose. The presence of n-dodecane and nitric acid enhanced the radiolytic degradation of the solvent. The third phase formation behavior of Nd(III) decreased with increase of absorbed dose and the third phase was not observed at absorbed doses above 100 kGy. The recovery of Am(III) from the irradiated system was near quantitative in five contacts. The study revealed that the extraction and stripping behavior of the irradiated solvent was quite satisfactory for partitioning of minor actinides from real wastes. [ABSTRACT FROM AUTHOR]

The radiation stability of N,N-di-dodecyl- N′, N′-di-octyl-3-oxapentane-1,5-diamide (DDODGA) was studied by γ-irradiation of the solvent up to a absorbed dose of 1,000 kGy. The effect of γ-irradiation on the radiolytic degradation of DDODGA was assessed by measuring the distribution ratio of Am(III) ( D) as well as the third phase formation in the irradiated DDODGA- n-dodecane solution. The D in the irradiated solution decreased with increase of absorbed dose. The critical aqueous concentration of Nd(III) above which the third phase forms, increased with increase of absorbed dose. However, the limiting organic concentration of Nd(III) remained at ~25 mM irrespective of the absorbed dose. Recovery of Am(III) from the radiolytically degraded organic phase showed that back extraction of Am(III) was quantitative in a few contacts using dilute nitric acid. Our studies clearly indicated that radiolytic degradation of DDODGA in n-dodecane is marginal even at the absorbed dose of 1,000 kGy, and therefore DDODGA is a potential candidate for minor actinide partitioning. [ABSTRACT FROM AUTHOR]