Sustainable Strategy for Microplastic Mitigation: Fe3O4 Acid-Functionalized Magnetic Nanoparticles for Microplastics Removal
Ivanilson da Silva de Aquino, Ester de Araújo Freire, Alisson Mendes Rodrigues, Otilie E. Vercillo, Mauro Francisco Pinheiro da Silva, Mateus Faustino Salazar da Rocha, Míriam Cristina Santos Amaral, Ariuska Karla Barbosa Amorim
Abstract
Microplastic (MPs) pollution has emerged as a critical environmental issue due to its persistent accumulation in ecosystems, posing risks to aquatic life, food safety, and human health. In this study, magnetic Fe3O4 nanoparticles functionalized with citric acid (Fe3O4@AC) were used to remove high-density polyethylene (HDPE), low-density polyethylene (LDPE), and polypropylene (PP) MPs from an aqueous medium. Fe3O4@AC was synthesized via the coprecipitation method and characterized by morphology (SEM), crystalline phases (XRD), chemical aspects (FTIR), and surface area (nitrogen sorption isotherms). The MPs removal efficiency of Fe3O4@AC was evaluated based on the initial concentration, contact time, and pH. The adsorption isotherm and kinetics data were best described by the Sips and pseudo-second-order models, respectively. Fe3O4@AC removed 80% of the MPs at a pH of 6. Based on experimental observations (zeta potential, porosity, and SEM) and theoretical insights, it was concluded that hydrogen bonding, pore filling, and van der Waals forces governed the adsorption mechanism. Reusability tests showed that Fe3O4@AC could be reused up to five times, with a removal efficiency above 50%. These findings suggest that Fe3O4@AC is a sustainable and promising material for the efficient removal of microplastics from wastewater, offering a reusable and low-impact alternative that contributes to environmentally responsible wastewater treatment strategies.