Transport of functional group modified polystyrene nanoplastics in binary metal oxide saturated porous media

Metal oxides exist in porous media in the form of composite metal oxides, which can significantly affect the transport and transformation of pollutants in the soil environment. In this study, binary metal oxide porous media were prepared to explore the effects of solution chemistry, and the presence of binary metal oxides on the transport of functional group modified polystyrene nanoplastics (PSNPs) in saturated porous media. The results show that the existence of binary metal oxides significantly affects the migration ability of PSNPs in saturated porous media. The increase of ionic strength and the presence of multivalent cations affect the transport capacity of PSNPs in porous media. The types of binary metal oxides affect the migration of PSNPs in saturated porous media. The surface roughness and electrostatic interaction are important factors affecting the retention of PSNPs on the surface of binary metal oxide saturated porous media. The surface morphology has a more far-reaching impact. In addition, DLVO theory cannot fully explain the interaction between PSNPs and saturated porous media in the presence of Al³⁺. This study's results help provide some theoretical support for the migration of microplastics in the soil environment.