Simultaneous Removal of NO2 and C6H6 in an NO2/C6H6 Mixture in Air by 172-nm Xe2 Excimer Lamp at Atmospheric Pressure

NO2 and C6H6 in an NO2(200 ppm)/C6H6(200 ppm) mixture were simultaneously removed in air at atmospheric pressure using a 172-nm vacuum ultraviolet (VUV) Xe2 excimer lamp. Reactants and products before and after photoirradiation were analyzed using an FTIR spectrometer. Results show that NO2 and C6H6 were finally converted to HNO3 and CO2, respectively, by 172-nm photolysis of the NO2/C6H6 mixture. Although the removal rate of NO2 in the NO2/C6H6 mixture was nearly the same as that of pure NO2 in air, the C6H6 removal delayed until a sufficient reduction of NOx (NO2, NO, and NO3) concentrations. In order to obtain information on these results, computer simulation of decomposition processes was carried out. The delay of the C6H6 removal in the NO2/C6H6 mixture was explained by 42–82 times larger reaction rate constants of the O(3P) + NOx reactions than that of the O(3P) + C6H6 reaction.