Efficient magnetic adsorption of polystyrene nanoplastic from aqueous solutions by eco-friendly Fe3O4 nanoparticles: Removal, kinetic and isotherm modeling studies

Abstract

Today, nanoplastics (NPs) are a growing environmental concern due to their persistence and widespread distribution, posing risks to ecosystems and human health. Their ability to transport pollutants makes them particularly dangerous, underscoring the urgent need for effective removal methods. Herein, we report the synthesis of an environmentally friendly material that enables the magnetic removal of polystyrene nanoparticles (PSNPs) from aqueous solutions by green chemistry approach. The material synthesized by using pine resin extract as a reducing and capping agent is iron oxide magnetic nanoparticles (PR@Fe₃O₄ MNPs). Spectroscopic (UV–Vis, FTIR) and microscopic (EFSEM, EDXS) techniques were used to characterize the nanoparticles and confirm the adsorption of PSNPs on the PR@Fe₃O₄ MNPs. X-ray diffraction (XRD) patterns indicated the crystalline nature of the nanoparticles and confirmed the preservation of the structure of PR@Fe₃O₄ MNPs after adsorption. The adsorption of PSNPs (with a diameter of 100 nm) was performed under varying conditions, including different contact times, dosages of PR@Fe₃O₄ MNPs, and concentrations of PSNPs. It was observed that the removal efficiencies of PSNPs (100 mg/L) ranged from 95.45% to 99.13% when the dosage of PR@Fe₃O₄ MNPs increased from 2.5 mg to 10.0 mg after 24 h, reaching the maximum adsorption capacity at 454.55 mg/g. Kinetic and isotherm studies indicated that the adsorption process fits best to a pseudo-second-order kinetic model and Langmuir isotherm, suggesting monolayer adsorption on homogeneous surfaces. Finally, the results of this study concluded that the green-synthesized PR@Fe₃O₄ MNPs can be used as effective and eco-friendly materials to remove PSNPs from aquatic environments.

Graphical abstract