A wet process for oxidation-absorption of nitric oxide by persulfate/calcium peroxide

This study develops and evaluates a novel wet method for NO removal using a Na2S2O8/CaO2 solution. The effects of these two components both and alone in solution, Na2S2O8 concentration, CaO2 concentration, initial pH, reaction temperature, and the concentrations of NO and O-2 on NO removal efficiency were evaluated using a bubbling reactor. The combination of Na2S2O8 and CaO2 had a synergistic effect on NO removal efficiency. NO removal was effected by CaO2 concentration, reaction temperature and the initial solution pH, while Na2S2O8 concentration and O-2 concentration had little effect. The NO removal efficiency decreased linearly from 94.5 % to 75.1 % when the NO concentration increased from 139 to 559 ppm. The products were characterized using XRD, XPS and IC, and CaSO4 center dot 2H(2)O, NO3- and SO42- were found to be the main products. The EPR analysis showed that free radicals of O-2(center dot-), SO4 center dot- and center dot OH were the key species involved in the NO removal process. Finally, the corresponding reaction mechanisms were proposed.