Effect of Initial Toluene Concentration on the Photooxidation of Toluene -NO x - Air Mixture - I. Change of Gaseous Species

An experimental investigation of the gas-phase photooxidation of toluene-NO-air mixtures at sub-ppm concentrations has been carried out in a 6.9 m3, indoor smog chamber irradiated by blacklights. Measured parameters in the toluene-NO experiments included , NO, NO, NO, CO, SO toluene, and air temperature. The initial toluene concentration ranged from 225 ppb to 991 ppb and the initial concentration ratio of toluene/NO in ppbC/ppb was in the range of 5～20. It was found that the variation of gaseous species with irradiation time caused by the photooxidation of toluene-NO-air mixtures depended on the initial toluene concentration for similar concentration ratio of toluene/NO. The dependency of initial toluene concentration on the photooxidation of toluene-NO-air mixtures for toluene/NO=5～6 seemed to be opposite to that for toluene/NO=10～11. The arriving time at maximum ozone concentration depended on both initial toluene concentration and initial concentration ratio of toluene/NO. However, the maximum concentration of ozone formed by photooxidation depended only on the initial toluene concentration.luene concentration.