Magnetic iron oxide/carbon composites derived from MIL-88A(Fe) for efficient removal of polystyrene nanoplastics from water

The efficient removal of nanoplastics from aquatic environments remained a critical environmental challenge. Herein, MIL-88A(Fe) was employed as the precursor to fabricate a series of magnetic iron oxide/carbon composites (M-T, M = MIL-88A(Fe), T = 300–800 °C) via controlled pyrolysis. Among them, the optimized M-600 preserved a spindle–like morphology, with superparamagnetic Fe 3 O 4 nanoparticles uniformly embedded in the carbon matrix. M-600 exhibited exceptional adsorption performance with excellent magnetic separability, achieving 97.46% removal efficiency for polystyrene nanoplastics (PSNPs) (pH=7, 0.3 g·L −1 , 25 °C). It worked within the pH range of 2.0–7.0. The efficiency was 63.97% after five cycles, and the maximum adsorption capacity was 69.97 mg·g −1 . The adsorption kinetics followed the pseudo-first-order model, while the adsorption isotherm was well fitted by the Sips model. Its favorable wettability facilitates interfacial contact, and the efficient capture of PSNPs was dominated by electrostatic attraction and further strengthened by π–π stacking interactions. Overall, this study provides a technically reliable and promising strategy for nanoplastic removal.