Removal of polystyrene nanoplastics from aqueous solutions by a novel magnetic zeolite adsorbent

Nanoplastics (NPs) made from plastic fragments have attracted wide attention due to their extensive distribution and potential harm to organisms. In this study, the zeolite as raw samples, a new magnetic zeolite (MZ) adsorbent was successfully synthesized by co-precipitation method to remove polystyrene nanoplastics (PSNPs). The adsorption amounts of PSNPs by MZ sample enhanced with the increases of PSNPs initial concentration and the temperature in aquatic solutions. The maximum equilibrium adsorption amount could achieve 34.2 mg/g. The solution pH, co-existing anions, and ionic strength could significantly affect the removal of PSNPs. Comparing different adsorption models, it displays that the pseudo-second-order and Sips models could well fit the adsorption process of PSNPs by MZ. Based on the XPS analysis, the iron oxide functional groups exhibit an important role in capturing PSNPs. The potential adsorption mechanisms of PSNPs are summarized as electrostatic attraction, complexation, and π-π conjugation. Overall, the synthesized magnetic material can effectively remove NPs from aqueous solutions.