Removal of Elemental Mercury in Flue Gas with H_2O_2 Solution Catalyzed by Zn-Doped BiFeO_3

摘要

Magnetic Zn-doped BiFeO3 catalyst was synthesized by the tartaric acid sol gel method, and its characteristics were characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, Brunauer Emmett Teller technique, and vibration sample magnetometer. The catalytic activity of Zn-BiFeO3 was evaluated for activating H2O2 to oxidize elemental mercury in a self-designed bubbling reactor, and the effects of the Zn doped ratio in catalyst, catalyst dosage, H2O2 concentration, solution pH, and reaction temperature on the removal of Hg degrees were also investigated systematically. The result indicated that the removal efficiency of Hg-0 achieved 81% under the optimum conditions, in which the Zn doping ratio was 0.2, H2O2 concentration was 0.15 mol L-1, catalyst dosage was 0.3 g L-1, solution pH was 6, reaction temperature was 50 degrees C, and Hg degrees concentration was 50 mu g/m(3). Moreover, it was demonstrated indirectly that (OH)-O-center dot and HO2 center dot were the active species when Hg degrees was oxidized to oxidation state mercury using H2O2 solution catalyzed by 0.2Zn-doped BiFeO3, where tert-butyl alcohol and benzoquinone were used as quenchers. The reaction mechanism was established eventually through the characterizations of catalyst and reaction product.