EXTRACTION OF Am(lll) AND Eu(lll) NITRATES BY 2-6-DI-(5,6-DIPROPYL-1,2,4-TRIAZIN-3-YL)PYRIDINES 1

Abstract

The extraction of Am(lll) and Eu(lll) by 2,6-di(5,6-dipropyl-1,2,4-triazin-3-yl)-pyridines from mostly 1·9 M (HNO₃ + NH₄NO₃) was studied. The compound with n-propyl (DPTP) forms dimers and trimers in mixed branched alkanes modified with 2-ethyl-1-hexanol. The self-association is supported by enhancing the HNO₃ concentration from 0·3 to 0·9 M. In the above modified diluent, DPTP extracts Am(lll) and Eu(lll) nitrates as the complexes Am(NO₃)₃HNO₃-3B and Eu(NO₃)₃HN033B. The Am(lll)/Eu(lll) separation factor is typically 100 -120. The extraction and separation efficiency of DPTP strongly decreases in the order of diluents (each modified with 2-ethyl-1-hexanol) branched alkanes > cyclohexane > 2-methyl-4-pentanone > 2-ethylhexyl acetate > benzene > chlorobenzene > xylene. 1-Octanol and 2-ethyl-1-hexanol modifiers support appropriately the solubility of protonated forms of DPTP in branched alkanes, and moderately enhance the extraction of Am(lll) and Eu(lll). 1-Butanol modifier allows a higher extraction efficiency but supports less the solubility. The optimum extraction and separation efficiency is attained at 10 - 20 vol% modifier. The isopropyl analogue extracts Am(lll) more effectively than DPTP, but the extraction is slow and the separation from Eu(lll) is inefficient.