Plastics, when released into the environment, undergo surface weathering due to mechanical abrasion and ultraviolet (UV) exposure that leads to the formation of microplastics. Weathering also introduces oxygen functional groups on the surface, which will affect surface interactions compared to pristine plastics. In this study, the adsorption of selected model contaminants of high environmental relevance was evaluated at different level of abiotic and biotic transformation to understand how microplastics aging influences contaminant adsorption on high density polyethylene (HDPE) and polypropylene (PPE). Microplastics were aged through an accelerated weathering process using UV exposure with or without hydrogen peroxide. The effect of UV aging on the microplastics’ morphology and surface chemistry was characterized by Fourier Transform Infrared Spectroscopy, X-Ray Photoelectron Spectroscopy, streaming Zeta potential, Brunauer–Emmett–Teller Krypton adsorption analyses and Computed X-Ray Tomography. Sorption of organic contaminants was found to be higher on aged microplastics compared to pristine ones for all contaminants investigated. This increase in sorption affinity was found to be associated with a change in the surface chemistry and not in an increase in specific surface area after aging. To evaluate if this higher sorption affinity of aged microplastics will change in the presence of biological surface weathering (i.e. biofouling),  pristine and aged microplastics were exposed to natural lake water for four weeks. Sorption isotherms were measured using biofouled microplastics to measure the combined sorption of the microplastics and accumulated biomass. The amount of microbial biomass accumulated on the surface was also evaluated to correlate the changes in sorption affinity with the change in microplastic biofouling. The results of this study emphasize the need to understand how contaminant-microplastics interactions will evolve as microplastics are altered by biotic and abiotic factors in the environment.

Impact of accelerated UV aging and biofilm formation on the sorption of organic and metallic compounds onto microplastics

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.