Studies on Am(III) separation from simulated high-level waste using cobalt bis(dicarbollide) (1-) ion derivative covalently bound to N,N'-di-n-octyl diglycol diamide as extractant and DTPA as stripping agent

The separation of minor actinides from high level liquid waste (HLLW) belongs to the principal challenges in current nuclear treatment. A derivative based on two cobalt bis(dicarbollide) (1(-)) ions covalently bound to the N,N'-di-n-octyl diglycolyl amide platform via diethyleneglycol chain with the formula {[(N,N'-(8-(OCH2 CH2)(2)-1,2-C2B9H10)(1',2'-C2B9H11)-3,3'-Co)(N,N'-n-C8H17)NCOCH2](2)O}Na-2 (TODGA-COSAN), dissolved in low polar mixture of hexyl methyl ketone and n-dodecane, was used as an extractant for efficient Am(III)/Eu(III) separation from PUREX HLLW. Am(III) could be selectively stripped from loaded organic phase by using a stripping agent composed from 0.05 M DTPA and 1 M citric acid as a buffer and 1 M NaNO3 at pH 3.0. Separation factor between europium and americium of 13 was achieved. The europium remaining in the organic phase could be consecutively effectively stripped by using solution of ammonium citrate or ammonium citrate with ammonium DTPA at pH similar to 7.