Selective extraction and separation of Ce(IV) from thorium and trivalent rare earths in sulfate medium by an α-aminophosphonate extractant

A novel extractant, di (2-ethylhexyl) (2-((2-ethylhexyl) amino) propan-2-yl) phosphonate (DEHAPP, abbreviated as B ), was synthesized for the selective extraction of Ce(IV) in sulfate medium. The effect of contact time, the H 2 SO 4 concentration, the DEHAPP concentration and temperature on the Ce(IV) extraction were studied systematically. DEHAPP exhibits a good extraction ability towards Ce(IV) when compared with other neutral organophosphorus extractants such as Cyanex 923, Cyanex 925 and DEHEHP. The extraction equilibrium constants and thermodynamic parameters (Δ G , Δ H and Δ S ) were calculated. The extraction reaction of Ce(IV) is an endothermic process. The extracted complexes were determined to be H 2 SO 4 · B ( org ) and Ce(HSO 4 ) 2 SO 4 ·2 B ( org ) . A extraction process to selectively recover Ce(IV) from bastnaesite leaching was proposed, by which the purity of cerium product reached 99.5% with a yield of 90.7%.