KINETIC STUDY OF THE PHOTOCHEMICAL PERSISTENCE OF THE PESTICIDE METRIBUZIN IN AQUEOUS MEDIUM: INFLUENCE OF MICROPLASTICS

• Grant number: 22/16890-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2023
• End date: April 30, 2023
• Field of knowledge: Engineering - Chemical Engineering
• Principal Investigator: Antonio Carlos Silva Costa Teixeira
• Grantee: Matheus Larrondo Portiolli
• Host Institution: Escola Politécnica (EP). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Pesticides have been intensively used around the world to control pests in agriculture, raising environmental concerns associated with the toxicity of these compounds to humans and other organisms. Particularly, metribuzin (MTZ), classified as an emerging contaminant of environmental concern, is toxic to the environment. Added to this problem is the presence of microplastics in surface water, especially when considering their bioaccumulation and their possible role as adsorbents and vehicle for organic pollutants. In environmental aquatic matrices, the photochemical processes responsible for the degradation of emerging contaminants result from direct and indirect photolysis. In this context, the objective of this project is to study the photochemical degradation kinetics of MTZ in aqueous medium in simulated sunlight, as a result of photolytic processes and reactions mediated by photoinduced reactive species-RPS (HO*, 3CDOM*, 1O2), in the absence and presence of polyethylene (PE) and polystyrene (PS) microparticles. It is expected to obtain fundamental kinetic parameters for MTZ (direct photolysis quantum yield, second order kinetic constants of reactions with RPS), evaluate its adsorption on PE and PS microparticles and elucidate their role in the photo-oxidative degradation of the pesticide, seeking to understand its photochemical persistence in surface waters in the absence and presence of microplastics.