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Photoactivity assessment of TiO2 thin films using Acid Orange 7 and 4-chlorophenol as model compounds. Part I: Key dependencies

Paper ID Volume ID Publish Year Pages File Format Full-Text
27864 44047 2012 6 PDF Available
Title
Photoactivity assessment of TiO2 thin films using Acid Orange 7 and 4-chlorophenol as model compounds. Part I: Key dependencies
Abstract

Azo dye Acid Orange 7 (AO7) and 4-chlorophenol (4-CP) are frequently used model compounds for photocatalytic activity assessment of TiO2 thin films. This paper explores the key factors, such as: method of analysis, initial concentration, mass transfer and reaction kinetics, in order to help identify the optimal conditions for photocatalytic activity evaluation.It has been experimentally proved that simple visible absorption spectrophotometry can be used reliably to determine the concentration changes of AO7 during its photocatalytic degradation, but is inappropriate for 4-CP and liquid chromatography should be used instead. At low concentrations (10−5–10−4 M) the first order rate constant for the photocatalytic destruction of AO7 decreases with increasing [AO7], whereas for 4-CP, it remains unchanged. This effect is not due to an approaching monolayer surface coverage of the AO7 on the titania photocatalyst but instead is due to UV screening of the titania film by the dye AO7. Thus, initial degradation rates corrected for the screening effect of AO7 solution show a direct dependence on [AO7] under the experimental conditions used in this work. At stirring speeds lower than 890 rpm (for AO7) and 220 rpm (for 4-CP) the kinetics of organic destruction are controlled by the diffusion rate of a model compound (AO7 or 4-CP) to the surface of TiO2 layer.

► Investigation of key factors for photocatalytic activity evaluation of TiO2 thin films using AO7 and 4-CP as model compounds. ► Proved that Vis absorption spectrophotometry can be used reliably to determine the concentration of AO7 during its photocatalytic degradation. ► Observed rates of AO7 degradation were corrected for UV screening of the titania film by the dye AO7. ► At stirring speeds <890 rpm (AO7) and <220 rpm (4-CP) the degradation kinetics is controlled by the diffusion rate of a model compound (AO7 or 4-CP).

Keywords
TiO2 film; Photoactivity assessment; Acid Orange 7; 4-Chlorophenol; Kinetics
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Photoactivity assessment of TiO2 thin films using Acid Orange 7 and 4-chlorophenol as model compounds. Part I: Key dependencies
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 250, 15 December 2012, Pages 66–71
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us