Sorption of polycyclic aromatic hydrocarbons by microplastic films: Characterizing kinetics, isotherms, and impacts of sludge exposure

Microplastics can facilitate the transport of environmental contaminants through sorption, which impacts the bioavailability of these contaminants. Due to the prevalence of both microplastics and polycyclic aromatic hydrocarbons (PAHs) in sludge and wastewater systems, we investigated the effects of sludge exposure on the uptake of PAHs by polylactic acid (PLA) and polyethylene (PE) films. In general, rates of PAH sorption were found to increase with longer sludge exposure times. PLA exhibited negligible changes in sorption capacity due to a lack of significant chemical changes occurring during the first two weeks of sludge exposure. In comparison, sludge-aged PE exhibited increased PAH sorption capacity, likely due to decreases in film crystallinity and increases in surface area. Our results highlight how the sorption behavior of PLA and PE films evolves with sludge exposure and will help to better predict the fate and transport of environmental PAHs.