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Photocatalytic removal of 2,4-dichlorophenoxyacetic acid by using sol–gel synthesized nanocrystalline and commercial TiO2: Operational parameters optimization and toxicity studies

Paper ID Volume ID Publish Year Pages File Format Full-Text
46052 46429 2012 7 PDF Available
Title
Photocatalytic removal of 2,4-dichlorophenoxyacetic acid by using sol–gel synthesized nanocrystalline and commercial TiO2: Operational parameters optimization and toxicity studies
Abstract

A comparative study of the photoefficiency of two different TiO2 catalysts in the elimination, mineralization and detoxification of waters containing herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) and toxic intermediates was performed at laboratory scale. Commercial TiO2 (Degussa (Evonik) P25) and TiO2 synthesized by citrate sol–gel method (ECT-1023t) were selected as photocatalysts. Adsorption studies, kinetic analysis and an analysis of the effect of adding oxidizing agents (H2O2 and S2O82−) were carried out for both catalysts. The toxic effect of photocatalytic treatment at different reaction times was determined by marine bacteria Vibrio fischeri bioassay. The toxic effect on this organism of the main degradation intermediate 2,4-dichlorophenol (2,4-DCP) was higher than for the initial herbicide. The optimal operational variables to eliminate the herbicide and toxic intermediates were established for both catalysts. The most effective removal of 2,4-D and toxic intermediate 2,4-DCP was achieved using ECT-1023t as catalyst at pH 3 and pH 5. The inhibitory effect on V. fischeri growth in water containing 2,4-D after 2 h of photocatalytic treatment was negligible when using ECT-1023t as catalyst. Longer times were necessary to obtain similar results when using P25 as catalyst. The addition of H2O2 significantly enhanced the degradation and mineralization rate, with different optimal H2O2 concentrations for the tested catalysts. When using H2O2 as oxidizing agent, toxicity on V. fischeri was eliminated before 1 h of photodegradation treatment with both photocatalysts.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► ECT-1023t showed higher photocatalytic activity than Evonik P25 at natural pH. ► Production of toxic of intermediates (2,4-DCP) was reduced by using ECT-1023t. ► Toxicity was eliminated before 1 h of treatment using H2O2 as oxidizing agent.

Keywords
2,4-Dichlorophenoxyacetic acid; Photocatalysis; ECT-1023t; Vibrio fischeri; H2O2; FTIR
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Photocatalytic removal of 2,4-dichlorophenoxyacetic acid by using sol–gel synthesized nanocrystalline and commercial TiO2: Operational parameters optimization and toxicity studies
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 125, 21 August 2012, Pages 28–34
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