Abstract
The behaviors of NO2in N2and in air under the UV irradiation were studied at room temperature. NO2in N2decomposed quantitatively to NO and O2under a high pressure mercury lamp irradiation. The decomposition rate was proportional to the irradiation energy and the concentration of NO2. Under a low pressure mercury lamp irradiation NO2decomposed to NO and O2, and partially to N2and O2. The decomposition rate of NO2to N2was proportional to the concentration of NO2and the smaller value of the 1 st order rate constant was obtained in later stage of the reaction than that in the early stage.
In NO2-O2-N2mixture, NO2decomposed to NO and O2under a high pressure mercury lamp irradiation. The change between NO2and NO was in equilibrium because of the oxidation of NO formed, and the equilibrium concentration of NO2increased with the initial concentration of O2While, under a low pressure mercury lamp irradiation, the oxidation of NO2to higher oxides and the reduction of NO2to NO occured simultaneously. NO formed was oxidized to higher oxides in later stage. The oxidation rate increased with the initial concentration of O2and was retarded by NO formed.
No effect by H2O was observed in the behavior of NO2 in NO2-O2-N2mixture under a high pressure mercury lamp irradiation. While, under a low pressure mercury lamp irradiation, NO did not form and the oxidation rate increased remarkably in the presence of H2O, and the rate was proportional to the concentration of NO2.
