Follow-up research of ultraviolet catalyzing vaporized H2O2 for simultaneous removal of SO2 and NO: Absorption of NO2 and NO by Na-based WFGD byproduct (Na2SO3)

In the previous work, gas phase oxidation of NO was completed through a method of ultraviolet catalyzing vaporized H2O2, and the results were satisfactory. While the problem of how to effectively absorb NO2 and NO had not yet been studied, this paper was attempted to carry out the absorption of NO and NO2 by various absorbents. The experimental results indicated that Na2SO3 was the best absorbent, and the effects of some key factors on the simultaneous removal were assessed, such as the concentration of Na2SO3, the reaction temperature, the solution pH, the concentration ratio of NO2 to NO, the coexistence gases SO2 and O-2, and the conventional anions. Under the optimal conditions, the efficiencies of SO2, NO2 and NO were 99.2%, 89% and 78% respectively. The alkaline atmosphere and high temperature were beneficial for NO2 removal. An appropriate amount of SO2 could promote the removal of NO2 and NO. O-2 exhibited an inhibition on removing NO2 and a promotion on removing NO. Sulfate was demonstrated as a promoter for NO removal. Bicarbonate and nitrite were favorable for NO2 removal. The products were identified as sulfate and nitrite based on the characterization by XRD, the reaction mechanism was speculated finally. (C) 2017 Elsevier B.V. All rights reserved.