fulltext.study @t Gmail

Photolysis of thin films of cypermethrin using in situ FTIR monitoring: Products, rates and quantum yields

Paper ID Volume ID Publish Year Pages File Format Full-Text
28995 44112 2008 8 PDF Available
Title
Photolysis of thin films of cypermethrin using in situ FTIR monitoring: Products, rates and quantum yields
Abstract

Cypermethrin is a synthetic pyrethroid insecticide commonly used both indoors and outdoors. Following its application, cypermethrin residues are exposed to atmospheric oxidants, such as ozone and OH radicals, as well as to solar radiation. The current work focuses on the photochemical degradation of cypermethrin under 254 nm, 310 nm, and solar radiation; including kinetic analysis, quantum yields, and identification of volatile and non-volatile products. The investigation was done using a combined FTIR set-up for parallel analysis of condensed and gas phases. Complementary GC–MS analysis was conducted on the pesticide’s residues. Quantum yields of 0.41 and 0.25 were obtained under 254 and 310 nm, respectively. These values are in agreement with outdoor studies and are higher than the known yields for aqueous solution. The values obtained under all tested conditions suggest that photodegradation of adsorbed cypermethrin is a major outdoor degradation pathway. Oxygen presence was found to increase degradation rate and quantum yield.The identified photoproducts include 3-phenoxybenzaldehyde, 3-phenoxybenzoic acid, acetonitrile (m-phenoxyphenyl), and cypermethrin isomers on the surface and formic acid, CO2 and CO in the gas phase. The condensed phase products are more polar than the parent molecule, suggesting that they may be susceptible to a greater leaching rate in soils.

Keywords
Cypermethrin; Photolysis; Pesticides; Photooxidation
First Page Preview
Photolysis of thin films of cypermethrin using in situ FTIR monitoring: Products, rates and quantum yields
Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 200, Issues 2–3, 15 December 2008, Pages 262–269
Authors
, ,
Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering