Simultaneous desulfurization and denitrification through an integrative process utilizing NaClO2/Na2S2O8

SO2 and NO emitted from coal-fired power plants have caused serious air pollution in China. In this paper, a novel complex oxidant, NaClO2/Na2S2O8, was prepared for simultaneous removal of SO2 and NO through a pre-oxidation method. The cooperative effect as well as mechanism between NaClO2 and Na2S2O8 was elucidated, with the corresponding best ratio of 4 wt%:4 wt%. The effects of various reaction factors on the simultaneous removal were investigated, i.e. the adding rate of the complex oxidant, the pH of the complex oxidant, the reaction temperature, the flue gas residence time and the coexistence gases. The experimental results indicated that the desulfurization process was mainly controlled by the sodium humate (HA-Na) absorption, while the denitrification was significantly affected by various conditions. Under the optimal conditions, the removal efficiencies for SO2 and NO were 100% and 82.7%, respectively. Compared with our previous works, NaClO2/Na2S2O8 has some superiorities of less dosage of the complex oxidant, rapid reaction rate and more efficient in NO removal. According to the characterizations of removal products by XRD, FT-IR and UV-Vis, and the literature references, the reaction mechanism was speculated. (C) 2017 Elsevier B.V. All rights reserved.