title: Photo-catalysis of bromacil under simulated solar light using Au/TiO₂: evaluation of main degradation products and toxicity implications.
abstract: Bromacil (5-bromo-3-sec-butyl-6-methyluracil) is a substituted uracil herbicide used worldwide. It is not readily biodegradable and has the potential to contaminate different types of water bodies with possible impact on diverse non-target species. In this work, degradation of bromacil in aqueous Au/TiO2 suspension under simulated sunlight allowed fourteen degradation products to be identified. The photodegradation of bromacil followed (pseudo) first order kinetics in the presence of 0.2 g L(-1) of Au/TiO2 with a half-life of 25.66 ± 1.60 min and a rate constant of 0.0271 ± 0.0023 min(-1). Transformation routes of the photo-catalytic degradation of bromacil were then proposed. Complementary toxicity assessment of the treated bromacil solution revealed a marked decrease in toxicity, thereby confirming that by-products formed would be less harmful from an environmental point of view. Photo-catalytic degradation of bromacil thus appears to hold promise as a cost-effective treatment technology to diminish the presence of this herbicide in aquatic systems.
authors.affiliation: Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Kasetsart University, Bangkok, 10903, Thailand.
authors.forename: Dusit
authors.initials: D
authors.lastname: Angthararuk
authors.forename: Pakawadee
authors.initials: P
authors.lastname: Sutthivaiyakit
authors.forename: Christian
authors.initials: C
authors.lastname: Blaise
authors.forename: François
authors.initials: F
authors.lastname: Gagné
authors.forename: Somyote
authors.initials: S
authors.lastname: Sutthivaiyakit
mesh_terms: D001976:Bromouracil / Q000031:analogs & derivatives* / Q000737:chemistry / Q000633:toxicity; D002384:Catalysis; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D006046:Gold / Q000737:chemistry; D006207:Half-Life; D006540:Herbicides / Q000737:chemistry*; D007700:Kinetics; D008027:Light; D013058:Mass Spectrometry; D015394:Molecular Structure; D053761:Nanocomposites / Q000737:chemistry*; D010782:Photolysis; D014025:Titanium / Q000737:chemistry; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*; D014961:X-Ray Diffraction
chemical_list: D006540:Herbicides; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D001976:Bromouracil; D006046:Gold; D014025:Titanium; C004590:bromacil