Development of a Green Technology for Mercury Recycling from Spent Compact Fluorescent Lamps Using Iron Oxides Nanoparticles and Electrochemistry

The widespread use of energy efficient mercury containing lamps and impending regulations on the control of mercury emissions has necessitated the development of green mercury control technologies such as nanosorbent capture and electrolysis regeneration. Herein we describe a two-step green technique to remove and recycle mercury from spent compact fluorescent lamps (CFLs). The first element included the assessment of capture efficiencies of mercury vapor on magnetite (Fe3O4) and maghemite (γ-Fe2O3), naturally abundant and ubiquitous components of atmospheric dust particles. Around 60 μg of mercury vapor can be removed up to 90% by 1.0 g of magnetite nanoparticles, within a time scale of minutes. The second step included the development of an electrochemical system for the mercury recycling and regeneration of used nanoparticles. Under optimized conditions, up to 85% of mercury was recovered as elemental mercury. Postelectrolysis regenerated iron oxide nanoparticles were used in several sorption–electrolysis cycles without loss of the adsorption capacity, morphology, and surface area. The low energy usage for electrolysis can be supplied by the solar panels. The implications of our results within the context of green technology are herein discussed.