Hg0 removal from flue gas by ionic liquid/H2O2

1-Alkyl-3-methylimidazolium chloride ionic liquids ([Cnmim] Cl, n = 4, 6, 8) were prepared. The ionic liquid was then mixed with hydrogen peroxide (H2O2) to form an absorbent. The Hg0 removal performance of the absorbent was investigated in a gas/liquid scrubber using simulated flue gas. It was found that the ionic liquid/H2O2 mixture was an excellent absorbent and could be used to remove Hg0 from flue gas. When the mass ratio of H2O2 to ionic liquid was 0.5, the absorbent showed high Hg0 removal efficiency (up to 98%). The Hg0 removal efficiency usually increased with the absorption temperature, while decreased with the increase of alkyl chain length in ionic liquid molecule. The Hg0 removal mechanism involved with Hg0 oxidation by H2O2 and Hg2+ transfer from aqueous phase to ionic liquid phase.