Cooperative removal of SO2 and NO using a cost-efficient triple-area control method

Chlorite-induced oxidation reaction has been demonstrated to be an efficient approach for simultaneous removal of SO2 and NO, however the dosage of used chlorite is always high, which is unfavorable for economic operation and controlling the secondary environmental impact. The motivation of this work is to explore if it is possible to reduce the chlorite dosage meanwhile guaranteeing a good removal of NO by utilizing a triple-area control method. This reaction system consists of three parts: (1) a 0.9 mM NaClO2 solution at 60 degrees C, (2) a water layer at 50 degrees C, and (3) a 80 mM Na2SO3 solution. The water layer was used to capture the ClO2 emitted from the NaClO2 solution to conduct a deep removal of NO. Na2SO3 solution was used to remove the produced NO2 and the residual ClO2 via redox reactions. Co-presence of SO2 and O-2 exhibited a great synergism in NO removal, but the presence of HCO3- remarkably suppressed the NO removal. According to the ion chromatography (IC) analysis, SO42- and NO3- were identified to be the main products, their concentration distributions in the triple-area were also revealed. The mechanisms of removal of SO2 and NO and the application prospective were proposed.