Eco-Corona Formation Enhances Cotransport of Nanoplastics and Organic Contaminants in Porous Media

The dynamic interactions between nanoplastics and environmental macromolecules, particularly the formation of eco-corona, have received growing attention. There is increasing evidence that eco-corona plays a critical role in determining the fate, transport, and impact of nanoplastics. In this study, we show that even a low mass of eco-corona formed on nanoplastics significantly affects the cotransport of nanoplastics and organic contaminants in porous media. Specifically, eco-corona formation promotes the transport of 4-nonylphenol with polystyrene nanoplastics, especially when the eco-corona forms after contaminant adsorption to nanoplastics. Spectroscopic evidence indicates that 4-nonylphenol molecules are sequestered between the nanoplastics and the eco-corona due to the simultaneous binding to surface O-functional groups of the nanoplastics and to the polar macromolecules preferentially acquired by the nanoplastics. Transport modeling and supplementary adsorption/desorption experiments confirm that this binding configuration effectively inhibits or retards the release of 4-nonylphenol from the nanoplastics-eco-corona complex. Conversely, for 2,2′,4,4′-tetrabromodiphenyl ether, an eco-corona inhibits its cotransport with nanoplastics by blocking the porous domains of the nanoparticles, which are the preferred binding sites for nonpolar, nonionic, hydrophobic compounds. The dynamic interplays between nanoplastics, macromolecules, and contaminants have important implications for predicting the spread, release, and bioaccumulation of plastic additives in aquatic environments.