PHOTOOXIDATION OF EXHAUST POLLUTANTS .1. DEGRADATION EFFICIENCIES, QUANTUM YIELDS AND PRODUCTS OF BENZENE PHOTOOXIDATION

The photochemical decomposition and oxidation of benzene was investigated in the gas phase by irradiation of benzene in an oxygen/ozone atmosphere with ultraviolet light from low and medium pressure mercury lamps. The degradation efficiency depends on the concentration of the pollutant, the power output of the UV-lamp, the ozone concentration and the residence time in the irradiated area. The quantum yields for photooxidation at 1 atm O-2 without addition of O-3 were measured to be < < 1, both at 185 and 254 nm, demonstrating loss channels of the electronically excited benzene which are fluorescence, internal conversion and intersystem crossing as well as the absence of chain reaction steps at both wavelengths.