Magnetic three-dimensional graphene-like framework carbon for efficient extraction of polystyrene nanoplastics from environmental water.

In this study, a three-dimensional graphene-like framework carbon (3DFC) was prepared via a high-temperature pyrolysis method, followed by the anchoring of Fe3O4 nanoparticles through Fe-O-C coordination bonds using a solvothermal process to obtain magnetic Fe-3DFC, which was applied for the efficient extraction of polystyrene nanoplastics (PS-NPs) from environmental water samples and subsequent quantitative determination by liquid chromatography coupled with a UV detector. The physicochemical properties of Fe-3DFC were systematically characterized using multiple analytical techniques. The effects of pH, adsorbent dosage, adsorption time, and PS-NPs concentration on adsorption performance were comprehensively investigated. Adsorption experiments indicated that equilibrium was reached within 15 min, with a removal efficiency exceeding 99.2%. Fitting results based on the Freundlich isotherm model (R2 = 0.9917) and the pseudo-second-order kinetic model (R2 = 0.9889) demonstrated that the adsorption process was predominantly governed by multilayer chemical adsorption on heterogeneous surfaces. After five adsorption-desorption cycles, the adsorption efficiency remained above 86.32%. In real water samples including lake water, Yellow River water, and tap water, the recoveries for spiked PS-NPs ranged from 87.4% to 105.6%. Mechanistic studies revealed that the synergistic interaction between electrostatic attraction and π-π stacking was the primary driving force for efficient adsorption. Overall, Fe-3DFC exhibits high adsorption capacity, rapid magnetic separation, and excellent reusability, providing a promising platform for the rapid enrichment and sensitive detection of trace nanoplastics in environmental water samples.