Simultaneous absorption of NO and SO2 into FeII–EDTA solution coupled with the FeII–EDTA regeneration catalyzed by activated carbon

The simultaneous removal of NO and SO2 from flue gases can be realized with Fe(II)–ethylenediamineteraacetate(EDTA) solution. Activated carbon is used to catalyze the reduction of FeIII–EDTA to FeII–EDTA to maintain the capability of removing NO of the Fe–EDTA solution. The reductant is the sulfite/bisulfite ions produced by SO2 dissolving into the aqueous solution. Experiments have been performed to determine the effects of activated carbon of coconut shell, FeII–EDTA concentration, Fe/EDTA molar ratio, SO2 partial pressure, NO partial pressure and SO42− concentration on the combined elimination of NO and SO2 with FeII–EDTA solution coupled with the FeII–EDTA regeneration catalyzed by activated carbon. According to the experimental results, activated carbon not only catalyzes the reduction of FeIII–EDTA by sulfite/bisulfite greatly but also avoids the release of N2O. The NO removal efficiency increases with the initial FeII–EDTA concentration and SO2 partial pressure. The ratio of Fe/EDTA and the SO42−concentration has little effect on the catalytic reduction of FeIII–EDTA. The optimal initial NO concentration range is from 600 ppm to 900 ppm. The experimental results manifest that the FeII–EDTA solution coupled with catalytic regeneration of FeII–EDTA can maintain high nitric oxide removal efficiency for a long period of time.