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

The photochemical decomposition and oxidation of benzene was investiga ted in the gas phase by irradiation of benzene in an oxygen/ozone atmo sphere with ultraviolet light from low and medium pressure mercury lam ps. The degradation efficiency depends on the concentration of the pol lutant, the power output of the UV-lamp, the ozone concentration and t he residence time in the irradiated area. The quantum yields for photo oxidation 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 electro nically excited benzene which are fluorescence, internal conversion an d intersystem crossing as well as the absence of chain reaction steps at both wavelengths.