Abstract
Photocatalytic oxidation of 4-chlorophenol (4-CP) was investigated by using a multi-stage reactor system with titania immobilized on a stainless steel mesh under an irradiation of 11 W low pressure mercury lamp with the wave length of 200-300 nm. Catalytic activities of 4-chlorophenol degradation over Ag/TiO2 (Degussa P25), Au/TiO2 (Degussa P25) and temperature treated TiO2 (Degussa P25) were studied in both the batch suspended and continuous immobilized systems. The presence of either temperature treated TiO2, Ag/TiO2 or Au/TiO2 affects insignificantly the 4-CP degradation compared to the photolysis. In contrast, TiO2 significantly affects the intermediates, hydroquinone and hydroxyhydroquinone. The presence of Ag and Au does not improve the catalytic activity of TiO2 in the 4-CP degradation but it affects the degradation of intermediate products. The commercial TiO2 was immobilized on the cylindrical stainless steel mesh by dip-coating with the suspension of TiO2 (Degussa P25) in methanol and used as the catalyst in the multi-stage reactor unit. The titania on the stainless steel mesh support was found to be well adhered and its activity was still high after the regeneration.
