Removal of Hg⁰ from flue gas using Fe-based ionic liquid

Fe-based alkylimidazolium halide ionic liquids ([bmim]·FeXCl₃, X=Cl and Br) were prepared by a two-step reaction. And then the ionic liquids were characterized by infrared spectroscopy, Raman spectroscopy, nuclear magnetic resonance, thermogravimetric analysis and viscosity measurements. The Hg⁰ removal performance of the ionic liquid was also investigated in a gas/liquid scrubber using simulated flue gas. It was found that the ionic liquid possessed low viscosity and high thermal stability, and could be used as an absorbent for Hg⁰ removal from the flue gas. The ionic liquid showed high Hg⁰ removal efficiency (up to 98%) in the temperature range of 60-100°C. The Hg⁰ removal mechanism involved with Hg⁰ oxidation by the anion of ionic liquid and the regeneration of the anion.