Extraction of certain radionuc1ides by bipicolinamides as new extractants from nitric acid medium

Abstract

Two new symmetrical bipicolinamides (pyridine2,6-dicarboxamide), viz., N, N'-tetrahexyl bipicolinamide (THBPA) and N, N'-tetra-(2-ethylhexyl) bipicolinamide (TEHBPA) have been synthesized and characterized. The extracting ability of these extractants for U(VI), Th(IV) and Fe(III) and some selected fission products such as Cs, Sr(II), Co(II) and Eu(III) from nitric acid solutions have been compared with that of the two parallel structure monoamides(pyridine-4-carboxamide), viz., N,N'-dihexyl isonicotainamide (DHINA) and N,N'-di-(2-ethylhexyl)-isonicotainamide (DEHINA). TEHBPA shows higher extraction efficiency for U(VI), Th(VI) and Fe(III) than THBPA. A systematic investigation has been carried out on the extraction behavior of U(VI) with the two newly prepared bipicolinamides. The stoichiometry of the extracted species of U(VI) conforms to UO₂(NO₃)₂.2(bipicolinamides). The extraction behavior of U(VI), Th(IV) and Fe(III) with gamma-irradiated bipicolinamides and monoamides has been studied as a function of absorbed doses.