Current challenges in photocatalysis: Improved photocatalysts and appropriate photoreactor engineering

Current challenges in photocatalysis: Improved photocatalysts and appropriate photoreactor... The photocatalytic activity of different commercially available titanium dioxide materials is compared employing dichloroacetate (DCA−) as the model pollutant. A mechanism is presented evincing that one photon is sufficient to initiate the complete mineralization of one DCA− molecule. The observed non-linear dependence of the photonic efficiency ζ of the DCA− degradation upon the incident photon rate is explained by a simple mathematical model considering only one-electron charge transfer and recombination reactions on the semiconductor particle. Since photonic efficiencies below 1% are observed when aromatic compounds are used as model pollutants, an electron-shuttle mechanism is proposed involving the benzoquinone/hydroquinone redox couple and resulting in an overall enhancement of the electon/hole recombination. Newly synthesized colloidal Ti/Fe mixed oxide particles exhibit higher activity for the degradation of dichloroacetate than pure TiO2 colloids, however, they still suffer from cathodic corrosion problems. Finally, a self-contained thin film fixed bed reactor (TFFBR) is presented which can be operated as a stand-alone system gaining the energy for the pump operation from an appropriate photovoltaic module and regulating the water flow as a function of the solar flux. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Research on Chemical Intermediates Springer Journals

Current challenges in photocatalysis: Improved photocatalysts and appropriate photoreactor engineering

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Publisher
Springer Journals
Copyright
Copyright © 2000 by VSP
Subject
Chemistry; Catalysis; Physical Chemistry; Inorganic Chemistry
ISSN
0922-6168
eISSN
1568-5675
D.O.I.
10.1163/156856700X00255
Publisher site
See Article on Publisher Site

Abstract

The photocatalytic activity of different commercially available titanium dioxide materials is compared employing dichloroacetate (DCA−) as the model pollutant. A mechanism is presented evincing that one photon is sufficient to initiate the complete mineralization of one DCA− molecule. The observed non-linear dependence of the photonic efficiency ζ of the DCA− degradation upon the incident photon rate is explained by a simple mathematical model considering only one-electron charge transfer and recombination reactions on the semiconductor particle. Since photonic efficiencies below 1% are observed when aromatic compounds are used as model pollutants, an electron-shuttle mechanism is proposed involving the benzoquinone/hydroquinone redox couple and resulting in an overall enhancement of the electon/hole recombination. Newly synthesized colloidal Ti/Fe mixed oxide particles exhibit higher activity for the degradation of dichloroacetate than pure TiO2 colloids, however, they still suffer from cathodic corrosion problems. Finally, a self-contained thin film fixed bed reactor (TFFBR) is presented which can be operated as a stand-alone system gaining the energy for the pump operation from an appropriate photovoltaic module and regulating the water flow as a function of the solar flux.

Journal

Research on Chemical IntermediatesSpringer Journals

Published: Jan 1, 2000

References

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