Adsorption behavior and mechanism of perfluorooctane sulfonate on nanosized inorganic oxides

[Display omitted] •Nano-oxides have much higher adsorption capacity for PFOS than bulk particles.•PFOS adsorption on nano-oxides is pH-dependent.•Electrostatic attraction and hydrogen bond are responsible for PFOS sorption.•Co-existing PFOS and Cu(II) greatly enhances their sorption on nano-oxides.•Formation of bilayer PFOS structure leads to enhanced Cu(II) adsorption. Adsorption of perfluorooctane sulfonate (PFOS) on manufactured nanoparticles (NPs) is critical for understanding their transport and fate in aquatic environments. In this study, the adsorption behavior of PFOS on nanosized Al2O3, Fe2O3, SiO2 and TiO2 was examined in terms of adsorption isotherms and influences of pH, ionic strength and heavy metallic cations. The nano-oxides had much higher adsorption capacities than bulk particles due to higher surface hydroxyl density. PFOS adsorption showed strong pH dependence due to different species of surface hydroxyl groups on nano-oxides. Besides electrostatic interaction, sulfonic group of PFOS possibly formed hydrogen bonds on the surface of nano-oxides. Because of the bridging effect in the co-adsorption process, the coexisting PFOS and heavy metallic cations greatly enhanced their adsorption onto the nano-oxides. Comparative adsorption of different perfluorinated sulfonates indicated the possible formation of bilayer PFOS adsorption on the nano-oxides, leading to the enhanced Cu(II) adsorption on the sulfonic groups of PFOS on the surfaces through electrostatic interaction.