Extraction of Am(III) and lanthanide(III) ions from HNO3 solutions using N,N′-dimethyl-N,N′-diphenylpyridine-2,6-dicarboxyamide

The distribution ratios (D) of Am(III) and the lighter trivalent lanthanide (Ln(III)) ions between HNO3 solution and a CHCl3 solution containing N,N'-dimethyl-N,N'-diphenylpyridine-2,6-dicarboxyamide (DMDPhPDA) were determined. DMDPhPDA has not only two amide sites but also a nitrogen donor atom. The D values increased with an increase in the concentration of HNO3. The D values for Am(III), Eu(III), and Nd(III) between 4 M HNO3 solution and a CHCl3 solution of 0.5 M DMDPhPDA were determined to be 1.3, 0.25, and 0.24, respectively, which suggests that Am(111) can be extracted more selectively than Eu(III) and Nd(III) at this relatively high concentration of HNO3 solution. The separation factor (D-Am/D-Eu) with DMDPhPDA is higher than that with malonamides and diglicolamides. The D values and separation factors are independent of the concentration of Am(III) and Ln(III) in the range of 10(-8) M to 10(-1) M.