Extraction of actinides(III), (IV), (V), (VI), and lanthanides(III) by structurally tailored diamides

Eleven diamide extractants having the different backbones were synthesized and their extractability for lanthanides(III) and actinides(III), (IV), (V) and (VI) were measured and compared. The diamides investigated include (CH2)(n)-(CONR1,R-2)(2), (n = 0, 1, 2, 3), O-((CH2)(n')-CONR1,R-2)(2), S-((CH2)(n)-CONR1,R-2)(2), and SS-((CH2)(n')-CONR1,R-2)(2), (n', n, n''' = 1, 2). The diglycolamide introducing an ether oxygen into the main frame, O-(CH2-CONR1,R-2)(2), exhibited the highest extractability for An(111), (IV) and (VI), as compared with the other bidentate diamides. It is clear from the present results that the thiadiglycolamide, TDGA, which substitutes ether sulfur atom for oxygen in DGA molecule, also enhances the extraction of actinides. The lanthanide pattern, the distribution ratios vs. the atomic number, by diglycolamide in HNO3-n-dodecane system exhibited a gradual increase of distribution ratio with increase in the atomic number, the opposite trend to that obtained by the other diamides.