Microplastic Adsorption on Magnetic Nanoparticles: PET on CoFe2O4

Microplastic pollution is a significant and growing environmental concern. Polyethylene terephthalate (PET) is one of the most prevalent microplastics, posing substantial risks to aquatic ecosystems. A promising removal technique is magnetic extraction, utilizing hydrophobic magnetic nanoparticles (MNPs) to adsorb microplastics for subsequent separation from water. In this work, we investigate the adsorption of PET microplastics onto oleic acid/oleylamine (OA/OAm) capped cobalt ferrite (CoFe2O4) MNPs using a combined computational and experimental approach. Experimentally, CoFe2O4 MNPs have been synthesized, functionalized to enhance hydrophobicity, and applied in PET adsorption studies, with the material’s adsorption characterized using a combination of transmission electron microscopy (TEM) and Fourier transform infrared (FTIR), energy-dispersive X-ray (EDX), X-ray photoelectron (XPS), and ultraviolet–visible (UV-Vis) spectroscopy. Density functional theory (DFT) calculations have been employed to model the adsorption process, with time-dependent density functional theory (TDDFT) methods employed to obtain the optical absorption spectra in the UV-Vis regime. By combining these techniques, we show the mechanism of PET adsorption on CoFe2O4 MNPs is via charge transfer to the surface, with an estimated PET uptake on OA/OAm capped CoFe2O4 MNPs of ∼57%. These findings provide both a fundamental understanding of microplastic adsorption on MNPs and an effective strategy for mitigating microplastic contamination in water.