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Solar photocatalytic decomposition of two azo
dyes on multi-walled carbon nanotubes (MWCNTs)/TiO 2 composites |
Huilong WANG,Shuqin LIU,Hui WANG,Wenfeng JIANG, |
Department of Chemistry,
Dalian University of Technology, Dalian 116023, China; |
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Abstract Multi-walled carbon nanotubes (MWCNTs)/TiO2 composite photocatalysts with high photoactivity were prepared by sol-gel process and further characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), and UV-vis absorption spectra. Compared to pure TiO2, the combination of MWCNTs with titania could cause a significant absorption shift toward the visible region. The photocatalytic performances of the MWCNTs/TiO2 composite catalysts were evaluated for the decomposition of Reactive light yellow K-6G (K-6G) and Mordant black 7 (MB 7) azo dyes solution under solar light irradiation. The results showed that the addition of MWCNTs enhanced the adsorption and photocatalytic activity of TiO2 for the degradation of azo dyes K-6G and MB 7. The effect of MWCNTs content, catalyst dosage, pH, and initial dye concentration were examined as operational parameters. The kinetics of photocatalytic degradation of two dyes was found to follow a pseudo-first-order rate law. The photocatalyst was used for seven cycles with photocatalytic degradation efficiency still higher than 98%. A plausible mechanism is also proposed and discussed on the basis of experimental results.
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Keywords
sol-gel
multi-walled carbon nanotubes (MWCNTs)/TiO2 composite
photocatalysis
azo dye
solar irradiation
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Issue Date: 05 September 2010
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