Microwave photocatalysis III. Transition metal ion-doped TiO2 thin films on mercury electrodeless discharge lamps: preparation, characterization and their effect on the photocatalytic degradation of mono-chloroacetic acid and Rhodamine B
✍ Scribed by Hana Žabová; Vladimír Církva
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 2009
- Tongue
- English
- Weight
- 348 KB
- Volume
- 84
- Category
- Article
- ISSN
- 0268-2575
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✦ Synopsis
Abstract
BACKGROUND: Mercury electrodeless discharge lamps (Hg‐EDLs) were used to generate UV radiation when exposed to a microwave field. EDLs were coated with doped TiO~2~ in the form of thin films containing transition metal ions M^n+^ (M = Fe, Co, Ni, V, Cr, Mn, Zr, Ag). Photocatalytic degradation of mono‐chloroacetic acid (MCAA) to HCl, CO~2~, and H~2~O, and decomposition of Rhodamine B on the thin films were investigated in detail.
RESULTS: Polycrystalline thin doped TiO~2~ films were prepared by dip‐coating of EDL via a sol–gel method using titanium n‐butoxide, acetylacetone, and a transition metal acetylacetonate. The films were characterized by Raman spectroscopy, UV/Vis absorption spectroscopy, X‐ray photoelectron spectroscopy (XPS), electron microprobe analysis and by atomic force microscopy (AFM). The photocatalytic activity of doped TiO~2~ films was monitored in the decomposition of Rhodamine B in water. Compared with the pure TiO~2~ film, the UV/Vis spectra of V, Zr and Ag‐doped TiO~2~ showed significant absorption in the visible region, and hence the photocatalytic degradation of MCAA had increased. The best apparent degradation rate constant (0.0125 min^−1^), which was higher than that on the pure TiO~2~ film by a factor of 1.7, was obtained with the Ag(3%)/TiO~2~ photocatalyst. The effect of doping level of vanadium acetylacetonate on the photocatalytic efficiency of the V‐doped TiO~2~ was determined.
CONCLUSIONS: Transition metal ion‐doped TiO~2~ thin films showed significant absorption in the visible region. The metal doped TiO~2~ photocatalyst (with an appropriate amount of V, Zr and Ag) on the Hg‐EDLs increased the degradation efficiency of MCAA in a microwave field. Copyright © 2009 Society of Chemical Industry