Fe 3 O 4 /Laser-Induced Graphene as an Adsorbent for Microplastics Emitted from Household Wastewater

Removal of microplastics (MPs), which pose a severe threat to humanity and ecosystems, is essential. Although extensive efforts have been made to efficiently remove MPs, it still remains a difficult task. We fabricated Fe 3 O 4 /laser-induced graphene, by simply irradiating a laser on the surface of a polymer prepared by homogeneously mixing iron oxide, lignin powder, and polydimethylsiloxane, to efficiently remove household-derived MPs. Subsequently, Fe 3 O 4 -laser-induced graphene particles (Fe 3 O 4 -LIGPs) were prepared through scrapping and heat treatment. The Fe 3 O 4 -LIGPs efficiently adsorbed three types of MPs (melamine—particle size: 2 and 10 μm, polystyrene—particle size: 10 μm, polyamide—particle size: 50 μm) within 300 min and could be easily separated from the solution by using magnetic force. The adsorption of the MPs on the Fe 3 O 4 -LIGPs followed the pseudo-first and second-order kinetics and the Freundlich isotherm model. The maximum adsorption capacities of the Fe 3 O 4 -LIGPs for the different types of MPs were 1400 (polyamide, 50 μm), 1250 (polystyrene, 10 μm), 1050 (melamine—10 μm), and 775 (melamine—2 μm) mg∙g −1 . The Fe 3 O 4 -LIGPs were reused seven times for each MP, after heat treatment, and their performance was evaluated. Graphic abstract