Oxidation removal of NO by in situ Fenton system: Factors and optimization

Abstract

Nitrogen oxides are harmful to human health and environment. In this study, the oxidation removal of NO through a new in situ Fenton (IF) system was investigated. The independent effects of gas flow rate, initial pH, Fe2+/H2O2 molar ratio and reagent temperature were discussed preliminarily. For the first three factors, the oxidation efficiencies of NO increased with the increase of the values and decreased when the values beyond 600 mL/min, 3 and 0.05, respectively. However, the oxidation efficiencies monotonously decreased to some extent with the rise of reagent temperature from 25 °C to 85 °C. Also, the individual significance of the above factors and the interactive effects of them for oxidizing the NO were determined by the response surface methodology (RSM). The fitted quadratic equation indicated that only the Fe2+/H2O2 molar ratio had a positive independent effect on the oxidation removal of NO, whereas the reagent temperature showed the main negative independent effect. Besides, the interactive effects of them were revealed through the response surface and counter plots. Finally, the predicted maximum oxidation efficiency of NO was 90.10%, and then the related optimal conditions were computed as 570 mL/min gas flow rate, 2.85 initial pH, 0.047 Fe2+/H2O2 molar ratio and 47 °C reagent temperature theoretically.