Photo-sensitized Degradation of Dye Pollutants on Amorphous TiO2 under Visible Light Irradiation

Abstract

Amorphous TiO2 (Am-TiO2) was prepared via a simple step through hydrolysis.The as-prepared Am-TiO2 was characterized by X-ray diffraction,X-ray photoelectron spectroscopy,UV-visible diffuse reflectance spectroscopy,and N2 adsorption-desorption.Large surface area (216 m2/g) and abundant surface hydroxyl group/chemical adsorbed water were observed on Am-TiO2.Compared with crystallized TiO2,the adsorption edge of Am-TiO2 exhibited a blue shift (from 411 to 378 nm).Rapid photo-sensitized degradation of rhodamine B (RhB) was achieved on Am-TiO2 under visible light (λ 420 nm) irradiation.The pseudo-first-order rate constant (k=0.0325 min-1) was 6.5 and 5.2 times that of anatase and TiO2 P25,respectively.Moreover,both the N-deethylation and cleavage of chromophore ring structure of RhB were observed on Am-TiO2 while only the latter path predominated on crystallized TiO2.The difference between cleavage of chromophore ring structure and N-deethylation was ascribed to different anchoring groups of RhB on TiO2 through-COOH and-N+Et2,respectively.Testing in 4 recycle experiments,the degradation rate of RhB did not change significantly,indicating the excellent stability and reusability of the Am-TiO2 photocatalyst.