title: Photochemical fate and photocatalysis of 3,5,6-trichloro-2-pyridinol, degradation product of chlorpyrifos.
abstract: In this study we have focused on 3,5,6-trichloro-2-pyridinol (TCP), degradation product of chlorpyrifos. Photolysis experiments were conducted in order to elucidate its degradation mechanism. Identification of products was performed using the LC-MS technique. To evaluate the mineralization efficiency, TiO2 photocatalytic study was performed. Under photolytic experimental conditions, the concentration of TCP after 120 min of irradiation reached 5.9 ± 1.5% of the initial concentration, while chloride concentration reached approximately 73% of total chloride concentration. The TOC measurements after 120 min of photocatalytic degradation experiment revealed high mineralization rate, i.e. 53.6 ± 1.9%, while chloride concentration reached 26.6 mg L(-1) what means almost quantitative transformation of organic chlorine into chloride. TIC chromatogram (ESI, negative ion mode) of the reaction mixture after 30 min of irradiation revealed the presence of several peaks. One of them has already been reported previously. Two other products have been identified in this study for the first time. They have been formed by radical attack of the reactive OH(•) species on the carbonyl group followed by the corresponding N-C or C-C bond cleavages and recyclization with formation of the pyrrol structures substituted with carboxylic groups. Both deprotonated molecules easily lose CO2 in ESI conditions.
authors.affiliation: Laboratory for Environmental Research, University of Nova Gorica, Vipavska 13, P.O. Box 301, 5000 Nova Gorica, Slovenia.
authors.forename: Romina
authors.initials: R
authors.lastname: Žabar
authors.affiliation: Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, Equipe Photochimie, BP 10448, F-63000 Clermont-Ferrand, France.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Sarakha
authors.affiliation: Organic Chemistry Department, Lomonosov Moscow State University, Moscow, 119991, Russia.
authors.forename: Albert T
authors.initials: AT
authors.lastname: Lebedev
authors.affiliation: Organic Chemistry Department, Lomonosov Moscow State University, Moscow, 119991, Russia.
authors.forename: Olga V
authors.initials: OV
authors.lastname: Polyakova
authors.affiliation: Laboratory for Environmental Research, University of Nova Gorica, Vipavska 13, P.O. Box 301, 5000 Nova Gorica, Slovenia; Faculty of Health Sciences, University of Ljubljana, Zdravstvena pot 5, 1000 Ljubljana, Slovenia. Electronic address: polonca.trebse@zf.uni-lj.si.
authors.forename: Polonca
authors.initials: P
authors.lastname: Trebše
mesh_terms: D002384:Catalysis; D004390:Chlorpyrifos / Q000032:analysis* / Q000528:radiation effects; D002851:Chromatography, High Pressure Liquid; D007700:Kinetics; D010782:Photolysis; D011728:Pyridones / Q000032:analysis* / Q000528:radiation effects; D053719:Tandem Mass Spectrometry; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000528:radiation effects
chemical_list: D011728:Pyridones; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; C012587:3,5,6-trichloro-2-pyridinol; D014025:Titanium; D004390:Chlorpyrifos
keywords: 3,5,6-trichloro-2-pyridinol; LC-MS; Photocatalysis; Photolysis