KINETICS AND PRODUCTS OF THE TIO2 PHOTOCATALYTIC DEGRADATION OF 2-CHLOROBIPHENYL IN WATER

The light-induced degradation of 2-chlorobiphenyl (2-CB) under simulat ed solar irradiation has been investigated in aqueous solutions contai ning TiO2 suspensions as photocatalysts. The apparent quantum yield fo r an initial 2-CB concentration C-0=3.8 mu g/mL at the natural pH was ca. 0.005The oxidation kinetics of 2-CB follows the Langmuir-Hinshelwo od kinetic model at natural pH. The primary degradation of 2-CB follow s a pseudo-first-order kinetics. Several reaction intermediates were i dentified using GC/FTIR/MS and ion chromatography. The products at the initial stage of the reaction were seven isomers of 2-chlorobiphenyl- ol and biphenyl-2-ol. These intermediates underwent further photocatal ytic oxidation via aldehydes, ketones, and acids finally into CO2 and HCl. The formation and fate of some of these compounds under irradiati on were also investigated. A reaction scheme involving hydroxyl radica ls has been proposed. (C) 1998 Elsevier Science Ltd.