Experimental Study on the Removal of NO from Coal-Fired Flue Gas by the Na₂SiO₃/Fenton System

A novel Na2SiO3/Fenton system was employed for NO removal from coal-fired flue gas in a bubble reactor. The NO removal efficiency of this system could reach 94.36% when the flue gas residence time was 3 s. The hydrolysis reaction of Na2SiO3 produced OH-, which made the solution alkaline, and the formation of iron-based colloids in the alkaline environment effectively catalyzed the generation of free radicals from H2O2, O-2(center dot-) radicals, which was the main reason for the increase of NO removal efficiency. The reaction of H2O2 catalyzed by iron-based colloids increased the solution pH, which could not only further improve the NO removal efficiency but also enhance the useless decomposition of H2O2. Na2SiO3 could buffer the solution pH, which weakened the ineffective decomposition of H2O2 and prolonged the effective denitrification time. The X-ray diffraction and ion chromatography analysis showed that NO was finally converted to NO3- and NO2-.