Recovery of rare earth elements from simulated fluorescent powder using bifunctional ionic liquid extractants (Bif-ILEs)

BACKGROUND: Numerous high purity ammonium-type ionic liquid extractants have been prepared for engineering purposes. Bifunctional ionic liquid extractants (Bif-ILEs) have been widely applied to separate and extract rare earths and metal ions with high extraction efficiencies and selectivities. In the present study, new Bif-ILEs [A336][P204] and [A336][P507] have been used to extract rare earths from a simulated solution of a fluorescent powder in a high concentration of Al(NO(3))(3). RESULTS: Bif-ILEs were prepared from Aliquat336 (A336) and the commercial organophosphorus acid extractants, P204 and P507. These extractants [A336][P204] and [A336][P507] have similar characteristics to neutral organophosphorus extractants. When these Bif-ILEs were used to extract RE(III) from a simulated waste fluorescent powder system a third phase appeared which could be eliminated by the addition of 10% isopropanol modifier. The coexisting Al(2)O(3) in the fluorescent powder was changed to a salting-out agent (Al(NO(3))(3)) in the extraction process and promoted the extraction efficiency of RE(III). Using a countercurrent extraction process at a phase ratio V(o) : V(w) = 4 : 1 and pH = 0.56, the RE(III) recovery reached 95.2% in 5-7 stages. Finally, the extractabilities of these bifunctional extractants were compared with the neutral organophosphorus extractants P350, TBP and Cyanex923 at different concentrations, initial pHs and temperatures. CONCLUSIONS: By comparison with other neutral organophosphorus extractants, Bif-ILEs [A336][P204] and [A336][P507] can be considered efficient potential extractants for separating and recycling REEs and Al(2)O(3) from waste fluorescent powder. (C) 2011 Society of Chemical Industry