Adsorption of fluoranthene and phenanthrene by virgin and weathered polyethylene microplastics in freshwaters

Concern exists regarding potential health impacts associated with contaminants of emerging concern (CECs) that adsorb to microplastics (MPs). Previous studies have examined MPs as potential contaminant vectors in marine environments as opposed to freshwaters that represent drinking water sources. This study examined adsorption of two polycyclic aromatic hydrocarbons (PAHs), phenanthrene and fluoranthene, by virgin and weathered polyethylene (PE) in both artificial and natural freshwater matrices. Adsorption kinetics and isotherms conducted in artificial freshwater (AFW) consistently showed higher adsorption onto smaller (200 μm) PE when compared to 1090 μm PE. Adsorption mechanisms were primarily associated with hydrophobic interactions and monolayer chemisorption. As well, environmental factors including dissolved organic matter (DOC), pH, and polymer weathering also impacted adsorption. This work provides new insights regarding the adsorption of organic pollutants to better understand the risk of MPs in drinking water sources. [Display omitted] •Adsorption mechanism of two PAHs by PE is predominantly monolayer chemisorption.•Surface area plays a significant role in adsorption.•Hydrophobic interactions are identified as an important factor in adsorption.•PE weathering impacts surface area and oxygen-containing functional groups.•PAH adsorption in natural waters is complicated by competitive adsorption with DOC.