Simultaneous absorption of NO and SO 2 into Fe II–EDTA solution coupled with the Fe II–EDTA regeneration catalyzed by activated carbon

Abstract

The simultaneous removal of NO and SO 2 from flue gases can be realized with Fe(II)–ethylenediamineteraacetate(EDTA) solution. Activated carbon is used to catalyze the reduction of Fe III–EDTA to Fe II–EDTA to maintain the capability of removing NO of the Fe–EDTA solution. The reductant is the sulfite/bisulfite ions produced by SO 2 dissolving into the aqueous solution. Experiments have been performed to determine the effects of activated carbon of coconut shell, Fe II–EDTA concentration, Fe/EDTA molar ratio, SO 2 partial pressure, NO partial pressure and SO 4 2− concentration on the combined elimination of NO and SO 2 with Fe II–EDTA solution coupled with the Fe II–EDTA regeneration catalyzed by activated carbon. According to the experimental results, activated carbon not only catalyzes the reduction of Fe III–EDTA by sulfite/bisulfite greatly but also avoids the release of N 2O. The NO removal efficiency increases with the initial Fe II–EDTA concentration and SO 2 partial pressure. The ratio of Fe/EDTA and the SO 4 2−concentration has little effect on the catalytic reduction of Fe III–EDTA. The optimal initial NO concentration range is from 600 ppm to 900 ppm. The experimental results manifest that the Fe II–EDTA solution coupled with catalytic regeneration of Fe II–EDTA can maintain high nitric oxide removal efficiency for a long period of time.