title: Sorption of polycyclic aromatic hydrocarbons to polystyrene nanoplastic.
abstract: Microplastic has become an emerging contaminant of global concern. Bulk plastic can degrade to form smaller particles down to the nanoscale (<100 nm), which are referred to as nanoplastics. Because of their high surface area, nanoplastic may bind hydrophobic chemicals very effectively, increasing their hazard when such nanoplastics are taken up by biota. The present study reports distribution coefficients for sorption of polycyclic aromatic hydrocarbons (PAHs) to 70 nm polystyrene in freshwater, and PAH adsorption isotherms spanning environmentally realistic aqueous concentrations of 10(-5)  μg/L to 1 μg/L. Nanopolystyrene aggregate state was assessed using dynamic light scattering. The adsorption isotherms were nonlinear, and the distribution coefficients at the lower ends of the isotherms were very high, with values up to 10(9) L/kg. The high and nonlinear sorption was explained from π-π interactions between the planar PAHs and the surface of the aromatic polymer polystyrene and was higher than for micrometer-sized polystyrene. Reduction of nanopolystyrene aggregate sizes had no significant effect on sorption, which suggests that the PAHs could reach the sorption sites on the pristine nanoparticles regardless of the aggregation state. Pre-extraction of the nanopolystyrene with C18 polydimethylsiloxane decreased sorption of PAHs, which could be explained by removal of the most hydrophobic fraction of the nanopolystyrene. Environ Toxicol Chem 2016;35:1650-1655. © 2015 SETAC.
authors.affiliation: Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University, Wageningen, The Netherlands.
authors.forename: Lijing
authors.initials: L
authors.lastname: Liu
authors.affiliation: Physical Chemistry and Soft Matter, Wageningen University, Wageningen, The Netherlands.
authors.forename: Remco
authors.initials: R
authors.lastname: Fokkink
authors.affiliation: Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University, Wageningen, The Netherlands.|Institute for Marine Resources & Ecosystem Studies, Wageningen UR, IJmuiden, The Netherlands.
authors.forename: Albert A
authors.initials: AA
authors.lastname: Koelmans
mesh_terms: D000327:Adsorption; D005618:Fresh Water / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D053758:Nanoparticles / Q000032:analysis* / Q000737:chemistry; D010316:Particle Size; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis* / Q000737:chemistry; D011137:Polystyrenes / Q000032:analysis* / Q000737:chemistry; D013499:Surface Properties; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D011137:Polystyrenes; D014874:Water Pollutants, Chemical
keywords: Dynamic light scattering; Microplastic; Nanoplastic; Polycyclic aromatic hydrocarbons; Sorption