期刊
APPLIED CATALYSIS B-ENVIRONMENTAL
卷 103, 期 1-2, 页码 48-53出版社
ELSEVIER
DOI: 10.1016/j.apcatb.2011.01.007
关键词
Hydroxyl radical; Laser flash photolysis; Photo-Fenton; Titanium dioxide; Triphenylpyrylium
资金
- Spanish Government [CTQ2009-13699, CTQ2009-13459-C05-03]
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 center dot 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. (C) 2011 Elsevier B.V. All rights reserved.
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