Reversed micellar solubilization extraction and separation of thorium(IV) from rare earth(III) by primary amine N1923 in ionic liquid

Abstract

The extraction behavior of thorium(IV) sulfate by primary amine N1923 in imidazolium-based ionic liquid (IL) namely 1-octyl-3-methylimidazolium hexafluorophosphate ([C 8mim]PF 6) was systematically studied in this paper. Results showed that the extraction behavior was quite different from that using conventional solvent as diluent. A reversed micellar solubilization extraction mechanism was proposed for the extraction of thorium(IV) by N1923/[C 8mim]PF 6 via slope analysis method and polarized optical microscopy (POM)/transmission electron microscopy (TEM) observation. The salt-out agent, Na 2SO 4, was demonstrated to prompt this extraction mechanism. The extraction of several rare earths(III) (La, Ce, Nd, Gd, Er) by N1923/[C 8mim]PF 6 was investigated to evaluate the separation coefficients between Th(IV) and rare earth(III) (RE(III)). On this basis, we made a preliminary assessment for the possibility of using ionic liquid as diluent for the separation of Th(IV) from RE(III) in clean process.