Sorption and leaching behaviors between aged MPs and BPA in water: The role of BPA binding modes within plastic matrix

Due to the hydrophobicity and large specific surface area microplastics (MPs) have become the vector for the migration of environmental organic pollutants. Environmental aging process affects the physiochemical structure of MPs and their corresponding environmental behaviors, in which the effect of bisphenol A (BPA) binding mode within plastic matrix on aging behaviors of MPs is not reported. In this work, the structural properties and BPA sorption behaviors of low density polyethylene (LDPE) MPs with BPA additives and polycarbonate (PC) MPs with BPA monomers exposed to three types of artificial accelerated aging processes including UV/H₂O, UV/H₂O₂, and UV/Cl₂ systems were comparatively investigated. Virgin LDPE and PC exhibited obvious leakage of BPA additives or monomers. Aged LDPE had stronger sorption ability towards BPA in water environment with no observed leakage of BPA additives. While, aged PC had extremely high leakage of BPA monomers, which is similar to virgin PCs and was proved to be a persistent source of BPA release. The BPA sorption on aged LDPE or leaching from aged PC was influenced by aging processes, water pH, salinity, co-existing estradiol (E2), and water sources. This study reveals the potential ecological and environmental risks of MPs containing toxic additives/monomers during aging processes from a new perspective.