Polystyrene microplastics removal from aqueous solutions by magnetic iron nanoparticles

The presence of microplastics in aquatic environments, along with their impacts on humans and other organisms, poses a global challenge. Consequently, in recent years, methods for removing these pollutants from the environment have gained significant attention from researchers. This research focused on the removal of polystyrene microplastics from aqueous solutions using magnetic Fe₃O₄ nanoparticles. Polystyrene microplastics were prepared from waste generated by a plastic equipment manufacturing plant. The effects of microplastic concentration, Fe₃O₄ nanoparticle dosage, contact time, and pH on the removal of microplastics were systematically investigated. Adsorption isotherms were analyzed using the Langmuir, Freundlich, Temkin, and Sips models, while adsorption kinetics were evaluated with pseudo-first-order and pseudo-second-order kinetic models. Structural characterization was performed using FTIR, XRD, SEM/EDS, BET, and VSM analyses. Results showed that increasing the contact time from 15 to 120 minutes enhanced the removal rate from 52.55% to 80.81%, reaching equilibrium thereafter. Increasing the Fe₃O₄ nanoparticle dosage from 0.02 g to 0.1 g resulted in an increase in removal efficiency from 65.85% to 80.81%. Additionally, the removal percentage decreased from 63.76% at a microplastic concentration of 1200 ppm to 55% at 2400 ppm. The highest removal efficiency was observed under neutral pH conditions. Isotherm analysis indicated that the Freundlich model best described the adsorption process (R² = 0.96). The pseudo-second-order kinetic model (R² = 0.98) provided a better fit than the pseudo-first-order model. Due to their low cost, environmental compatibility, and effective adsorption performance, Fe₃O₄ magnetic nanoparticles represent a promising option for removing microplastics from aqueous environments.