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

• It is the first time of using Fe-based ionic liquid as an absorbent for Hg0 removal from flue gas.
• High Hg0 oxidation efficiency can be achieved.
• Hg0 oxidation by the anion of Fe-based ionic liquid and the regeneration of the anion coexist in the absorption process.

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.