Photooxidation of exhaust pollutants: III. Photooxidation of the chloroethenes: Degradation efficiencies, quantum yields and products

Article abstract of DOI:10.1016/0045-6535(94)90314-X

The photochemical decomposition and oxidation of the chloroethenes C₂H_4-XCl_X (x=1-4) was investigated in the gas phase by irradiation with a low pressure mercury lamp in an oxygen atmosphere. Degradation efficiencies directly depend on the number of chlorine atoms both at 185 and 254 nm. The quantum yields for degradation increase from 2-3 for vinyl chloride to > 100 for tri- and tetrachloroethene at 185 nm in the 10^-3 bar concentration range. At 254 nm we measured nearly time independent quantum yields of around 10 for tri- and 40 for tetrachloroethene. The photooxidation products and their mechanism of formation are discussed in detail.