Exposed Facets Mediated Interaction of Polystyrene Nanoplastics (Psnps) with Iron Oxides Nanocrystal

Nanoplastics (NPs), which are often detected in the natural environment, are regarded as a group of emerging pollutants. Hematite is a substance that exists widely in the surface environment and has an important impact on the environmental behavior of pollutants. Clarifying the migration of NPs requires an in-depth understanding of intrinsic interaction mechanisms of NPs with iron-containing minerals. The adsorption process of polystyrene nanoplastics (PSNPs) on the hematite exposed facets was systematically studied by adsorption experiments under different conditions, adsorption isotherm curves, Fourier Transform infrared (FTIR) spectroscopy and two-dimensional correlation spectroscopy (2D-COS) analyses. We found that PSNPs adsorbed on three exposed facets (e.g. {001}, {012} and {100}) of hematite through the electrostatic interaction but with different adsorption capacity. Adsorption models were established to explore the preferred interaction surface dependent on the exposed facets, and it was found that {012} surfaces were more favorable for PSNPs adsorption, while {001} surface has better adsorption capacity for PSNPs than {100} surface, which is due to the different density and proportion of hydroxyl groups on the exposed facets of hematite. These findings elucidated the dependence of PSNPs adsorption on the hematite facets, and illustrated the environmental impact of hematite on the migration of PSNPs