Fe3O4/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 Fe3O4/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, Fe3O4-laser-induced graphene particles (Fe3O4-LIGPs) were prepared through scrapping and heat treatment. The Fe3O4-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 Fe3O4-LIGPs followed the pseudo-first and second-order kinetics and the Freundlich isotherm model. The maximum adsorption capacities of the Fe3O4-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 Fe3O4-LIGPs were reused seven times for each MP, after heat treatment, and their performance was evaluated.