Unveiling the effect of polymer-selective interactions with perovskite nanomaterials on the transport of microplastics in saturated porous media

Abstract

Microplastics (MPs) have attracted global concern due to their persistence, mobility, and ecological risks in subsurface environments. Meanwhile, perovskite nanomaterials are also increasingly released into the environment due to their widespread use in material industry. However, the co-existence and potential interactions between perovskites and MPs remain poorly understood. This study systematically investigates and elucidates how perovskite nanoparticles influence the transport behaviors of four representative MPs, including polystyrene (PS), polyethylene terephthalate (PET), polyethylene (PE), and polypropylene (PP), in saturated porous media. A sorts of column experiments, extreme gradient boosting (XGBoost) regression model, zeta potential analysis, density functional theory (DFT) calculations, size distribution measurements, and adsorption experiments were used to conduct the exploration and elucidation. The findings indicated that BaTiO<inf>3</inf> and SrTiO<inf>3</inf> significantly inhibited the transport of PE and PP, but had negligible effects on PS and PET. Polymer type of MPs was confirmed to be the key factor dominating their transport with perovskites. This selective inhibition was verified to originate from the weaker electrostatic repulsion and stronger adsorption affinity between the perovskites and the PE and PP, compared to their interactions with PS and PET. These findings provide a mechanistic understanding of heterogeneous MPs-nanoparticle interactions and emphasize the importance of polymer type in controlling MPs mobility in soil-underground environments.