Effect of Wavelength and UV Transmission of Thin Film TiO2 on Photocatalysis.

A laboratory study of photocatalysis was conducted for purification of water contaminants employing a batch scale reactor with thin film TiO2 catalyst. The reactor was equipped with external light source, germicidal or blacklight lamp. Wavelength bands of irradiation and the direction of incident beam were changed to investigate the effect on degradation of benzene selected as a model compound. The reaction rate constants were evaluated for photocatalytic and photochemical reaction respectively. The shorter wavelength (254nm) was more effective by a factor of 4.4 than 300-400nm when the light was on the side of catalyst surface, while longer wavelength had advantage to penetrate through the catalyst layer or opaque media. The reactivity of photocatalysis was supposed to be closely related to the excitation of molecules by direct photolysis. The production of intermediates was also influenced by wavelength bands. These intermediates degraded in 60 minutes over photocatalyst.