Study on the removal of nitric oxide (NO) by dual oxidant (H2O2/S2O82−) system

In this paper, the removal of NO with dual oxidant (H2O2/S2O82−) system was studied in a bubble column reactor. The contrast experiment for a different system showed that the combination of Na2S2O8 and H2O2 had a significant synergistic effect on NO removal. The effects of Na2S2O8 concentration (0.02-0.2 mol/L), H2O2 concentration (0.25-2 %), molar ratio of H2O2 to Na2S2O8 (0.3:0.2-0.3:0.02 mol/mol), reaction temperature (21-70 °C) and initial pH value (1-11) on the removal efficiency of NO were investigated. The NO removal efficiency increased with the increase of Na2S2O8 and H2O2 concentrations. However, above 1 % hydrogen peroxide and 0.1 mol/L persulfate, the rate of increase in NO removal efficiency gradually slowed down. The optimal molar ratio of H2O2 to Na2S2O8 is 0.3:0.1 mol/mol. The optimum temperature for the thermal activation of dual oxidant (H2O2/S2O82-) system was 50 °C. The highest NO removal efficiency (82 %) was obtained at pH 11. The final ionic products were analyzed by ion chromatography. Combined with N material balance, NO3− was the final ionic product in spent reaction solution. A preliminary reaction mechanism for the removal of NO in dual oxidant (H2O2/S2O82−) solution was deduced. This dual oxidant (H2O2/S2O82−) system proved to be a promising reagent for wet denitration.