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Ionic solvent used to collect rare earth metals

Chemists at Belgian university KU Leuven claim to have developed a process based on ionic liquid technology for the recycling of the rare earth metals europium and yttrium from collected fluorescent and energy-saving lamps. The metals are then directly reusable in new lamps.

According to the scientists, the ionic liquid has advantages over traditional solvents including its selectivity for metal dissolution and its reusability.

Europium and yttrium are used in red lamp phosphor, a substance which transforms ultraviolet light into red light. This phosphor has been used for more than 40 years in colour TV screens and fluorescent lamp tubes.

Professor Koen Binnemans, scientific promoter at KU Leuven, said: “Because it is difficult to replace the red phosphor with a rare earth-free mixture, [we need to recycle it], focusing on the safe removal of mercury.”

Researcher David Dupont explained: “We use an ionic liquid as a solvent. It does not evaporate, it is inflammable and it works very selectively.

“We can design it in such a way that it dissolves only the red lamp phosphor so the recycled europium and yttrium can be directly reused. The ionic liquid is also reusable for a next cycle.”

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