Accelerated aging of polyvinyl chloride microplastics by UV irradiation: aging characteristics, filtrate analysis, and adsorption behavior

The extensive use of plastic products by people has led to the prevalence of microplastics (MPs) in aquatic and terrestrial ecosystems. MPs will be able to undergo multiple aging processes and release dissolved organic matter (DOM) in the aquatic environment, thereby further affecting the ecosystem. Therefore, this thesis systematically investigated the photo-aging properties of polyvinyl chloride (PVC), and characterized the changes in physicochemical properties; in addition, the DOM composition and fluorescence characteristics of MPs leachate were characterized by using TOC and 3D-EEMs. Our results showed that the O/C ratio can quantitatively characterize the surface aging of MPs. Furthermore, We chose Malachite green (MG) and Sulfamethoxazole (SMX), which are abundantly present in the aqueous environment, as the target pollutants, through adsorption experiments we established the regression equations of the equilibrium adsorption capacity of aging MPs with O/C ratio or CI and mean particle size. Exploring the relationship between aging properties and the adsorption capacity of microplastics can help predict the degree of aging and accumulation of hydrophilic contaminants in the natural environment.