Photocatalytic degradation of five sulfonylurea herbicides in aqueous semiconductor suspensions under natural sunlight |
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Authors: | Fenoll José Hellín Pilar Flores Pilar Martínez Carmen María Navarro Simón |
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Institution: | a Equipo de Calidad Alimentaria, Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario (IMIDA), C/Mayor s/n, La Alberca, 30150 Murcia, Spain b Departamento de Química Agrícola, Geología y Edafología, Facultad de Química, Universidad de Murcia, Campus Universitario de Espinardo, 30100 Murcia, Spain |
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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 (WO3), tin (IV) oxide (SnO2) 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 (Na2S2O8) 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 (t½) ranged from 8 to 27 min (t30W = 0.3-1.2 min) for sulfosulfuron and chlorsulfuron, respectively in the ZnO/Na2S2O8 system. None of the studied herbicides was found after 120 min of illumination (except chlorsulfuron, 0.2 μg L−1). |
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Keywords: | Water detoxification Sulfonylurea herbicides Photocatalytic oxidation Semiconductor materials |
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