Malonamide-Functionalized Ionic Liquid for Recovery of Rare-Earth Metals from End-Of-Life Products (Lamp Phosphors)

A novel functionalized ionic liquid, namely, malonamide-functionalized ionic liquid (MFIL) was synthesized and evaluated for the liquid-liquid extraction of rare-earth metals (REMs), transition, and other base metals from a hydrochloric acid medium. Theoretical calculations coupled with FT-IR studies were used to establish the mode of complexation between metal ions and the extracting moiety of MFIL. Uptake studies with multimetal feed solutions showed very good selectivity for REMs over other transition and base metals. Quantitative back extraction of REMs from loaded MFIL was accomplished using an acidic solution. MFIL showed preferential uptake of REMs over base and transition metals typically found in lamp phosphors.