Facile solvent extraction separation of Th-227 and Ac-225 based on room-temperature ionic liquids

摘要

New separation methodologies for radioisotopes are crucial to many medical applications. In this work, the solvent extraction of Th-227 and Ac-225 based on ionic liquids (ILs) was investigated using N,N,N',N'-tetraoctyldiglycolamide (TODGA) or di(2-ethylhexyl)phosphoric acid (HDEHP) as an extractant. Four ILs, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)-imide ([C _4mim][NTf _2]), 1-butyl-3-methylimidazolium bis-(perfluoroethanesulfonyl)imide ([C _4mim][BETI]), 1-butyl-2,3-trimethyleneimidazolium (trifluoromethanesulfonyl)imide ([BuI5][NTf _2]), and 1-benzyl pyridinium bis(trifluoromethanesulfonyl) imide ([PhCH _2Py][NTf _2]) with different cation or anion structural features were used as diluents for the separation of Th-227 and Ac-225. Excellent extraction efficiencies and selectivities were found for Th-227/Ac-225 when HDEHP was used as an extractant in these ILs. The effects of different extractant concentrations in ILs and different aqueous phase acidities on extraction efficiencies and selectivities of Th-227/Ac-225 are also presented. The success in separation of Th-227 and Ac-225 isotopes highlights great potentials of use of ionic liquids in isotope production.