Interaction among the simultaneous removal of SO2, NO and Hg0 by electrochemical catalysis in K2S2O8

Abstract

Sulfur dioxide (SO2), nitrogen oxides (NOx) and mercury (Hg0) produced by coal combustion are still the main sources of atmospheric pollutants. To find out the interaction among the simultaneous removal of SO2, NO and Hg0, the method of electrochemical catalysis in K2S2O8 was used to oxidize and remove these three pollutants from the simulated flue gas. Results indicated that the presence of SO2 promoted the oxidative absorption of NO under the condition of sufficient oxidant, while NO showed a weak competitive oxidation relationship to SO2. SO2 promoted the oxidative absorption of Hg0 through the generated SO32−, and Hg0 had no obvious effect on the desulfurization process due to its low concentration. NO promoted the oxidative absorption of Hg0 by its oxidation product NO2, and Hg0 also had no significant effect on the denitrification process due to the low concentration. During the removal of SO2, NO and Hg0 by electrochemical catalysis in K2S2O8, the electrochemical method could not only promote the rapid decomposition of S2O82− to produce a large amount of SO4−, but also help the electrolysis of H2O into HO. The oxidation of the solution was enhanced by oxidative free radicals such as SO4− and HO. Thus, the removal efficiency of SO2 oxidized by electrochemically catalyzed K2S2O8 was as high as 96%, the removal efficiency of NO could reach 90%, and the Hg0 removal efficiency was up to 92%.