Treatment of gas-phase volatile organic compounds (VOCs) by the UV/O3 process

The decomposition of several gas-phase volatile organic compounds (dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane, benzene, toluene, and o-xylene) in air streams by the UV/O-3 process were studied. The addition of ozone apparently improved the removal of VOCs by UV/O-3 process, and excessive ozone reduces the treatment efficiency of VOCs. The enhancement of UV light intensity promotes the decomposition of VOCs more effectively than the supplement of ozone. The mineralization and dechlorination of chloromethanes and chloroethanes by UV photolysis can be effectively achieved in the presence of ozone and were affected by the number of chlorine atom substituted on the molecules. The hydrogen abstraction from the VOCs molecule by hydroxyl radicals was inferred to be the major degradation pathway for the decomposition of VOCs. (C) 1999 Elsevier Science Ltd. All rights reserved.