title: Study of the photodegradation kinetics and pathways of hexaflumuron in liquid media.
abstract: Hexaflumuron, one of the benzoylphenylurea insect growth regulators, can be leached into surface water and thus having a potential impact on aquatic organisms. In this study, the photodegradation processes of hexaflumuron under high-pressure mercury lamp irradiation were assessed. The photodegradation kinetics were studied, as were the effects of pH, different light sources, organic solvents and environmental substances, including nitrate ions (NO3(-)), nitrite ions (NO2(-)), ferrous ions (Fe(2+)), ferric ions (Fe(3+)), humic acid, sodium dodecyl sulfate (SDS) and hydrogen peroxide (H2O2). Three photodegradation products in methanol were identified by gas chromatography-mass spectrometry (GC-MS). In general, the degradation of hexaflumuron followed first-order kinetics. In the four media studied, the photodegradation rate order was n-hexane > methanol > ultrapure water > acetone. Faster degradation was observed under high-pressure mercury lamp irradiation than under xenon lamp irradiation. The pH had a considerable effect, with the most rapid degradation occurring at pH 5.0. The photodegradation rate of hexaflumuron was promoted in the presence of NO3(-), NO2(-), Fe(2+), humic acid, SDS and H2O2, but inhibited by Fe(3+). Moreover, the presumed photodegradation pathway was proposed to be the cleavage of the urea linkage.
authors.affiliation: Department of Pesticide Science, Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, College of Plant Protection, Nanjing Agricultural University, Ministry of Agriculture, Nanjing, China.
authors.forename: Chengying
authors.initials: C
authors.lastname: Lu
authors.forename: Xing
authors.initials: X
authors.lastname: Yin
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Liu
authors.forename: Minghua
authors.initials: M
authors.lastname: Wang
mesh_terms: D001549:Benzamides / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry; D005296:Ferrous Compounds / Q000737:chemistry; D006812:Humic Substances; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009566:Nitrates / Q000737:chemistry; D009573:Nitrites / Q000737:chemistry; D010671:Phenylurea Compounds / Q000737:chemistry*; D055668:Photochemical Processes; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D005466:Fluorocarbons
chemical_list: D001549:Benzamides; D005290:Ferric Compounds; D005296:Ferrous Compounds; D006812:Humic Substances; D006861:Hydrogen Peroxide; D009566:Nitrates; D009573:Nitrites; D010671:Phenylurea Compounds; D012967:Sodium Dodecyl Sulfate; D012997:Solvents; C058039:hexafluoron; D005466:Fluorocarbons