Oxidative Absorption of Elemental Mercury from Flue Gas Using a Modified Fenton-like Wet Scrubbing System

A novel oxidative absorption process of elemental mercury (Hg-0 ) from flue gas using a Mn2+ -modified Fe-34/H2O2 wet scrubbing system (i.e., Mn2+-modified Fenton-like wet scrubbing system) was proposed. The influence of several technological parameters (concentration of Fe3+, H2O2, and Mn2+, solution pH value, solution temperature, and concentration of Hg-0, NO, and SO2) on Hg-0 absorption in a bubbling stirred reactor was investigated. On the basis of the detection of free radicals and reaction products, the routes and mechanism of Hg-0 oxidative absorption were also proposed. Results revealed that adding M2+ greatly promoted Hg-0 absorption using a Fenton-like wet scrubbing system. The enhancement role resulted from generating more *OH radicals (they were produced from the synergistic effect of Mn-21 and Fe3+ in a Mn2+-modified Fenton-like wet scrubbing system). Hg-0 removal efficiency was elevated via increasing the concentration of Fe3+, Mn2+, or H2O2 and was decreased by increasing the concentration of He, NO, or SO2 . Increasing the solution temperature and pH value showed double influence on Hg-0 absorption. He was oxidized by 'OH and H2O2 , and center dot H-O played a key role. 'OH was found to be produced from three sources: (1) Fe-21/H2O2 system, (2) Mn-21 +/H2O2 system, and (3) by the synergistic role of Fe3+ and Mn-21 in a Mn(2+)modified Fenton-like wet scrubbing system.