Molecular level insight into the different interaction intensity between microplastics and aromatic hydrocarbon in pure water and seawater

Abstract

The interaction of MPs and aromatic hydrocarbons in seawater and pure water was examined using experimental measurements, molecular dynamics (MD) simulations, and density functional theory (DFT) calculations in light of the potential health risks posed by microplastic (MPs)-associated aromatic hydrocarbon pollutants. Isothermal studies and MD simulations suggested that MPs have a stronger affinity for aromatic hydrocarbons in seawater. To uncover the mechanism, MPs' surface characteristics and their intermolecular interactions with aromatic hydrocarbons were examined. According to the research, MPs in seawater have less compact structure, bigger pores, and a higher specific surface area, all of which contribute to more sorption sites. Analysis of the intermolecular interaction indicated that MPs have a greater ability for molecular interactions in seawater and the interaction energy between MPs and aromatic hydrocarbons in seawater is higher. Additionally, seawater cations may act as bridges, which also accelerate sorption in seawater. In summary, this study provides a molecular-level understanding of MPs-aromatic hydrocarbons interaction and demonstrates that the interaction is stronger in seawater.

Keywords: Aromatic hydrocarbons; Density functional theory; Microplastics; Molecular dynamic simulations; Sorption.