Theoretical and experimental studies of NO removal in alkaline H2O2 system

NO in flue gas is one of the atmospheric pollutants, and it is necessary to study effective NO removal technology. It was identified that the alkaline H 2 O 2 system achieved over 98 % NO removal efficiency with a gas–liquid contact time of 3 s in this paper. This paper investigates the mechanism of NO removal in alkaline H 2 O 2 solution through both experimental and theoretical calculations. The results reveal the NO removal process can be divided into three phases by the NaOH/H 2 O 2 molar ratio. (1) The ∙O 2 – dominated phase, where trace metal Fe catalyzes ∙O 2 – radical generation from H 2 O 2 as Fe (OH) 2+ , reacting primarily with NO to form ONOO – . The energy barrier for this process is1.299 kcal/mol, with a reaction rate constant of 9.12 E + 11 s -1 M −1 . (2) The HO 2 – dominated phase, HO 2 – was generated through OH – and H 2 O 2 neutralization, which converts NO to NO 2 and regenerating OH – . The energy barrier for HO 2 – reacting with NO is 3.833 kcal/mol, and the reaction rate constant is 2.07E + 10 s -1 M −1 . (3) The O 2 2– dominated phase, O 2 2– was a further ionization of HO 2 – and converting NO to NO 2 – directly. The energy barrier for this process is 7.079 kcal/mol, and the reaction rate constant is 1.49 E + 08 s -1 M −1 .