Reclaiming mercury from spent fluorescent bulbs

Removing and reusing mercury from spent compact fluorescent lightbulbs helps keep the toxic element out of landfills, where it can enter the environment. In an effort to advance mercury recycling, researchers have developed a technique for processing spent CFLs that’s more energy efficient than current methods (ACS Sustainable Chem. Eng. 2016, DOI: 10.1021/acssuschemeng.5b01612). Existing recovery methods evaporate mercury at high temperature, separating it from other materials in the bulbs. Parisa A. Ariya of McGill University and her colleagues instead use iron oxide nanoparticles to trap mercury at near room temperature without heating. The team broke open CFLs within a vessel that was connected to a chamber loaded with nanoparticles. As mercury vapor from the bulbs flowed into the chamber, it stuck to the nanoparticles. The team then used magnets to transfer the nanoparticles to an electrochemical reactor in which the researchers drove off ionic mercury species and reduced them to elemental mercury. Their prototype system recovered up to 85% of the mercury and required only 20 W of power, little enough for a small solar panel to provide.