Preparation of a functional silica membrane coated on Fe3O4 nanoparticle for rapid and selective removal of perfluorinated compounds from surface water sample

• A novel magnetic nanocomposite was prepared in one step by a sol-gel process.
• The composite possessed good selectivity and rapid sorption kinetics for PFCs.
• The composite exhibited high removal efficiency for PFCs in surface water sample.
• The composite presented favorable reusability and stability for PFC removal.

In this study, a novel silica membrane functionalized with amino group and octyl-perfluorinated chain was prepared on the periphery of Fe3O4 nanoparticle (NP). The obtained nanocomposite (Fe3O4@SiO2-NH2&F13) exhibited good selectivity for perfluorinated compounds (PFCs) by electrostatic and fluorine-fluorine (F-F) interaction with the addition of size exclusion effect. In ethanol, the monolayer coverage of PFCs occurred on most of the binding sites and the adsorption capacity were in the range of 13.20–111.14 mg g−1. In aqueous solution, due to the hydrophobicity of perfluoroalkane chain, some PFCs (C ⩾ 8) may also stick together on the composite surface, which made the sorption amounts of these PFCs greatly enhanced. Thereafter, Fe3O4@SiO2-NH2&F13 was used for rapid and selective removal of nine PFCs from surface water sample. In 1 L of spiked water samples fortified at 0.5–50 ng L−1 levels, the composite showed a better removal efficiency (86.29%) for PFCs than that (58.61%) of powdered activated carbon (PAC). In addition, high concentrations (5–50 mg L−1) of humic acid (HA) had no significant influence on the removal performance of the composite for PFCs. Furthermore, Fe3O4@SiO2-NH2&F13 could be reused for several times with no obvious decrease in the removal efficiency. Thus, the magnetic nanocomposite could be used as an effective adsorbent for PFC removal from aquatic environment.

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