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Recovering rare earths from fluorescent and energy-saving lamps

Belgium – Chemists from Belgium’s KU Leuven university have developed a process based on ionic liquid technology for the recycling of europium and yttrium in fluorescent and energy-saving lamps, with the metals being directly reusable in new lamps.

Compared to traditional solvents, the ionic liquid approach offers a number of advantages, including selectivity for metal dissolution and reusability. Rare earth elements are indispensable for many modern electronic and cleantech applications but supply is subject to geopolitical tensions, thus fuelling an increased interest in recycling. Europium and yttrium are used in red lamp phosphor, a substance which transforms ultraviolet light into red light.

′Although it is already obligatory to collect end-of-life fluorescent and energy-saving lamps, the involved recycling is strongly focused on the safe removal of mercury from the waste,′ comments Professor Koen Binnemans from the university′s department of chemistry. ′Because of the technical complexity to recuperate europium and yttrium using traditional solvents, the powder containing these two critical metals is typically not reused.′

Researcher David Dupont says of the alternative developed at KU Leuven: ′Instead of employing an acid as the solvent, we use an ionic liquid; this is an organic dissolving agent that consists entirely of ions or electrically-loaded particles. It does not evaporate, it is inflammable and it works very selectively; we can design it in such a way that it only dissolves the red lamp phosphor. The recycled europium and yttrium can be directly reused. Furthermore, the ionic liquid is also reusable for a next cycle.′

With this new method, the recycling process requires less chemicals and energy, adds Binnemans. ′Both from a technical and environmental perspective, this approach is a very interesting alternative,′ he says.

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