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 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 SO2 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, SO2 partial pressure, NO partial pressure and SO42- concentration on the combined elimination of NO and SO2 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 N2O. The NO removal efficiency increases with the initial Fe-II-EDTA concentration and SO2 partial pressure. The ratio of Fe/EDTA and the SO42- 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. (C) 2010 Elsevier B.V. All rights reserved.