Comparing the sorption of pyrene and its derivatives onto polystyrene microplastics: Insights from experimental and computational studies

In this study, the sorption behaviors and mechanisms between polystyrene microplastics (micro-PS) and 4-rings polycyclic aromatic hydrocarbons (PAHs) pyrene (Pyr) and its derivatives (S-Pyr), including 1-methylpyrene (P-CH₃), 1-hydroxypyrene (P-OH), 1-aminopyrene (P-NH₂), 1-pyrenecarboxylic acid (P-COOH) were investigated at neutrality. The results revealed that the sorption rates of micro-PS for S-Pyr were higher than those for parent Pyr. Meanwhile, -CH₃ could slightly facilitate the sorption, whereas -OH, P-NH₂, and P-COOH intensively inhibit the sorption of S-Pyr onto micro-PS. The sorption capacities of Pyr/S-Pyr increased with decreasing size of micro-PS. Besides, the effects of salinity and temperature on the sorption characteristics of micro-PS for Pyr/S-Pyr depended on their substituents. Combined with experimental and computational methods, it could be concluded that the main sorption mechanisms were possibly hydrophobic interaction, π-π interaction and pore-filling. The observations reported here could improve predictions of environmental behaviors and bioavailability of PAHs and micro-PS.