fulltext.study @t Gmail

A photophysical approach to investigate the photooxidation mechanism of pesticides: Hydroxyl radical versus electron transfer

Paper ID Volume ID Publish Year Pages File Format Full-Text
46991 46455 2011 6 PDF Available
Title
A photophysical approach to investigate the photooxidation mechanism of pesticides: Hydroxyl radical versus electron transfer
Abstract

The role of hydroxyl radical in different solar photocatalytic processes, namely photo-Fenton, titanium dioxide-based oxidation and organic photocatalysis (triphenylpyrylium) has been investigated. Using a methodology based on the flash photolytic generation of OH from N-hydroxypyridine-2(1H)-thione, followed by t-stilbene trapping, the reaction rate constants of different pesticides (dimethoate, methidathion, alachlor and pyrimethanyl) with this reactive oxygen species in deaerated acetonitrile have been determined. The results obtained under photo-Fenton conditions are in reasonable agreement with the estimated rate constants; hence the assumption that the photo-Fenton reaction mainly involves participation of the hydroxyl radical seems plausible. The oxidation pattern using titanium dioxide was also investigated; however, under these conditions no clear correlation could be found due to participation of an alternative electron transfer mechanism.Finally, pyrimethanil was the most reactive pesticide when photodegradation was carried out in the presence of TPP, in spite of its low reactivity towards hydroxyl radical. Laser flash photolysis experiments evidenced that the reaction occurs via photoinduced electron transfer within a ground state complex; this is in good correlation with the relative amount of pyranyl radical formation.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► The role of OH has been investigated by laser flash photolysis. ► The reaction rate constants of five pesticides with OH have been determined. ► Results under photo-Fenton conditions are in agreement with OH involvement. ► The oxidation pattern using TiO2 suggests a mixed mechanism. ► Using TPP, photoinduced electron transfer occurs within a ground state complex.

Keywords
Hydroxyl radical; Laser flash photolysis; Photo-Fenton; Titanium dioxide; Triphenylpyrylium
First Page Preview
A photophysical approach to investigate the photooxidation mechanism of pesticides: Hydroxyl radical versus electron transfer
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
Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 103, Issues 1–2, 14 March 2011, Pages 48–53
Authors
, , , , , , , ,
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