The characterization and performance of a core–shell structured nanoplatform for fluorescence turn-on sensing and selective removal of perfluorooctane substance

The high dissociation energy of C-F bonds makes the natural degradation and decomposition of PFAS (per- and poly-fluoroalkyl substances) nearly impossible, leaving the PFAS wastes widely dispersed and permanently persisting in the natural environment. Consequently, detection and recognition techniques, as well as treatment technology, are highly desired for perfluorooctane sulfonate (PFOS) pollutants. In this work, we designed a core–shell magnetic-porous composite structure (denoted as Fe₃O₄@MCM-41/EY) for the sensing, adsorption, and removal of PFOS, using EY:CTAB (0.5 μM:80 μM, EY = Eosin Y, CTAB = cetyltrimethylammonium bromide) as the sensing probe, Fe₃O₄ nanoparticles as the core, and porous silica MCM-41 as the shell. The composite structure of Fe₃O₄@MCM-41/EY was confirmed by means of SEM (scanning electron microscope), magnetism, XRD (X-ray diffraction), N₂ adsorption/desorption, and TGA (thermal gravimetric analysis). A probe loading level of 28.5 % was determined. The probe showed an emission turn-on effect toward PFOS owing to the viscosity variation of the micelles caused by PFOS. A linear fitting equation was obtained as I/I₀ = 1.081 + 0.144 × 10⁶[PFOS], R² = 0.990, with good sensing selectivity and LOD (limit of detection) of 0.27 μM. In addition, Fe₃O₄@MCM-41/EY removed PFOS efficiently with an adsorption capacity of 0.126 mg/g. The novelty of this work was the simultaneous sensing, adsorption, and removal of PFOS using a core–shell magnetic-porous composite structure.