Asymmetric Membrane Containing Ionic Liquid [A336][P507] for the Preconcentration and Separation of Heavy Rare Earth Lutetium

A novel polymer inclusion membrane (PIM) was prepared for the preconcentration and separation of heavy rare earth element (HREE) Lutetium (Lu) from dilute solution. The membrane was composed of poly(vinylidene fluoride) (PVDF) as a matrix and bifunctional ionic liquid extractant [tricaprylmethylammonium][di(2-ethylhexyl)orthophosphinate] ([A336][P507]) as carrier, without any plasticizer. A weak physical effect existed between PVDF chain segment and [A336][P507], but no chemical interaction. Structure characterization and transport experiment both proved the membrane to be an asymmetric structure and LuCl3 would transport faster from surface with small pores to large pores. YbCl3 was transported much faster than LuCl3 which was different in liquid–liquid extraction. Preconcentration experiment realized a great acceleration on the transport of LuCl3. And the PIM was proved stable and durable. All these would provide a novel approach to the preconcentration and separation of Lu from dilute solution like leachate of southern ion adsorbed rare earth deposit.