Photo-catalysis of bromacil under simulated solar light using Au/TiO sub(2): evaluation of main degradation products and toxicity implications

• Published in: Environmental science and pollution research international Vol. 22; no. 2; pp. 1468 - 1479
• Main Authors: Angthararuk, Dusit, Sutthivaiyakit, Pakawadee, Blaise, Christian, Gagne, Francois, Sutthivaiyakit, Somyote
• Format: Journal Article
• Language: English
• Published: 01.01.2015
• Subjects: Byproducts; Degradation; Gold; Herbicides; Simulation; Titanium dioxide; Toxicity; Transformations
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-014-3425-3

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/TiO sub(2) 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 super(-1) of Au/TiO sub(2) with a half-life of 25.66 plus or minus 1.60 min and a rate constant of 0.0271 plus or minus 0.0023 min super(-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.