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Photocatalytic degradation of caffeine: Developing solutions for emerging pollutants

Paper ID Volume ID Publish Year Pages File Format Full-Text
55034 47038 2013 8 PDF Available
Title
Photocatalytic degradation of caffeine: Developing solutions for emerging pollutants
Abstract

The photocatalytic degradation of the psychoactive substance caffeine was studied using composites prepared with multi-walled carbon nanotubes and three different TiO2 materials: one synthesized by a modified sol–gel method and two others obtained from Evonik and Sigma–Aldrich. These materials were characterized by several techniques (e.g., DRIFT, XRD, N2 adsorption–desorption isotherms, TEM, SEM).The tested materials increased the caffeine degradation rate and the oxygenated groups created by acid treatment on the surface of the carbon nanotubes were crucial for the photocatalytic activity of all prepared composites. In addition, the photocatalytic activity of TiO2 from Sigma–Aldrich markedly increased with the addition of functionalized carbon nanotubes, which seems to be related with the larger TiO2 crystallite sizes and the better contact of these TiO2 particles with carbon nanotubes.Selective trapping of photogenerated holes and radicals by EDTA and tert-butanol shows that photogenerated holes are crucial on the photodegradation pathway but free radicals produced by photoexcited electrons do also participate in the mechanism and seem to be responsible for the higher activity observed for composites prepared with functionalized carbon nanotubes and TiO2 from Sigma–Aldrich in comparison to TiO2 alone. Films prepared with these composites revealed higher photocatalytic activity than films of TiO2 from Evonik.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (315 K)Download as PowerPoint slideHighlights► Caffeine can be removed from aqueous solutions using composite photocatalysts. ► CNT have a positive effect on the photo-activity of larger TiO2 anatase particles. ► Photogenerated holes are preferential pathways for the photodegradation process. ► Photoexcited electrons are responsible for the higher activity of SA/CNTf-20. ► Films of SA/CNTf-20 are more active than films of P25.

Keywords
Caffeine; Heterogeneous photocatalysis; Titanium dioxide; Carbon nanotubes; Scavengers for holes and radicals; Photocatalyst films
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 209, 15 June 2013, Pages 108–115
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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