Extraction and recovery of cerium(IV) and fluorine(I) from sulfuric solutions using bifunctional ionic liquid extractants

摘要

The extraction of cerium(IV) (Ce(IV)), fluorin (F~-) and Ce(IV)-F mixture solution from sulfuric acid medium using bifunctional ionic liquid extractants (Bif-ILEs) [trial-kylmethylammoniumj[di-(2-ethylhexyl)orthophosphinate]([A336][P507]), [trialkylmethylammonium] [di-2-ethylhexylphosphinate] ([A336][P204]) and [trialkylmethylammonium][bis 2,4,4-trimethyl-pentylphosphinate] ([A336][C272]) in n-heptane have been investigated in this report. The effect of H2SO4 concentration, extractant concentration and salting-out agent concentration has been investigated. The thermodynamic parameters have been determined, showing that the extraction was exothermic. The extraction mechanism has been obtained. The comparison for the extraction of Ce(IV), Ce(IV) in Ce(IV)-F mixture solution, cerium(III) (Ce(III)) and thorium(IV) (Th(IV)) has been investigated and the extraction efficiency order followed as: Ce(IV)>Th(IV)>Ce(III). Ce(IV) in Ce(IV)-F mixture solution was extracted in the form of CeF~(3+). The highest separation factor (β) values of Ce(IV)/Ce(III) and CeF~(3+)/Ce(III) were 3.32 x 10~3 and 2.58 x 10~3 in the [A336][P507] extraction system, 7.27 x 10~2 and 6.94 x 10~2 in the [A336][P204] extraction system, and 1.84 x 10~2 and 2.75 x 10~2 in the [A336][C272] extraction system, respectively, which indicated that Ce(IV) and Ce(IV) in Ce(IV)-F mixture solution could be separated from Ce(III) effectively.