SIMULTANEOUS PHOTOCHEMICAL GENERATION OF OZONE IN THE GAS-PHASE AND PHOTOLYSIS OF AQUEOUS REACTION SYSTEMS USING ONE VUV LIGHT-SOURCE

A more efficient use of vacuum ultraviolet (VUV) radiation produced by an immersed Xe-excimer light source (172 nm) was investigated for the oxidative degradation of organic pollutants in aqueous systems. All e mitted VUV radiation from one light source was used in two simultaneou s but separate photochemical reactions: (1) photochemical generation o f ozone by irradiating oxygen in the gas phase and (2) photolysis of t he aqueous reaction system. The gas stream containing the generated oz one is sparged into the reaction system, thus enhancing the oxidative degradation of organic pollutants. The photochemically generated ozone in the gas phase was quantitatively analyzed, and the kinetics of the degradation of 4-chlorophenol (4-CP) and of the dissolved organic car bon (DOG) were determined under different experimental conditions. The results show that the rates of degradation of the substrate and of th e DOC decrease in the order of the applied processes, VUV/O-3 > O-3 > VUV. (C) 1997 IAWQ. Published by Elsevier Science Ltd.