title: Photocatalytic degradation of five sulfonylurea herbicides in aqueous semiconductor suspensions under natural sunlight.
abstract: In the present study, the photocatalytic degradation of five sulfonylurea herbicides (chlorsulfuron, flazasulfuron, nicosulfuron, sulfosulfuron and triasulfuron) has been investigated in aqueous suspensions of zinc oxide (ZnO), tungsten (VI) oxide (WO(3)), tin (IV) oxide (SnO(2)) and zinc sulfide (ZnS) at pilot plant scale under natural sunlight. Photocatalytic experiments, especially those involving ZnO photocatalysis, showed that the addition of semiconductors in tandem with the oxidant (Na(2)S(2)O(8)) strongly enhances the degradation rate of the herbicides in comparisons carried out with photolytic tests. The degradation of the herbicides follows a first order kinetics according to the Langmuir-Hinshelwood model. In our conditions, the amount of time required for 50% of the initial pesticide concentration to dissipate (t(½)) ranged from 8 to 27 min (t(30W)=0.3-1.2 min) for sulfosulfuron and chlorsulfuron, respectively in the ZnO/Na(2)S(2)O(8) system. None of the studied herbicides was found after 120 min of illumination (except chlorsulfuron, 0.2 μg L(-1)).
authors.affiliation: Equipo de Calidad Alimentaria, Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario, C/Mayor s/n, La Alberca, 30150 Murcia, Spain. jose.fenoll@carm.es
authors.forename: José
authors.initials: J
authors.lastname: Fenoll
authors.forename: Pilar
authors.initials: P
authors.lastname: Hellín
authors.forename: Pilar
authors.initials: P
authors.lastname: Flores
authors.forename: Carmen María
authors.initials: CM
authors.lastname: Martínez
authors.forename: Simón
authors.initials: S
authors.lastname: Navarro
mesh_terms: D002384:Catalysis; D060766:Drinking Water / Q000737:chemistry; D004785:Environmental Pollutants / Q000737:chemistry*; D006540:Herbicides / Q000737:chemistry*; D010782:Photolysis; D012666:Semiconductors; D013453:Sulfonylurea Compounds / Q000737:chemistry*; D013472:Sunlight; D013535:Suspensions; D014025:Titanium / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D060766:Drinking Water; D004785:Environmental Pollutants; D006540:Herbicides; D013453:Sulfonylurea Compounds; D013535:Suspensions; D014867:Water; C009495:titanium dioxide; D014025:Titanium