Rapid magnetization and removal of microplastics from environment and food based on magnetic metal-organic framework Fe3O4@SiO2@MIL-53(Al)

Microplastics (MPs) are now not only emerging as pollutants in the environment, but their current state of contamination in food is also a cause for concern. It is necessary to focus how to control, reduce, and even remove MPs. In this study, a magnetic metal-organic framework (MOF) material, FeO@SiO@MIL-53(Al), was synthesized and applied to simulate the magnetization and removal of four types of MPs. FeO@SiO@MIL-53(Al) was characterized by various means to demonstrate its successful synthesis as a core-shell nanomaterial. The conditions of the method were optimized by examining the effect of time, the mass ratio of material to MPs, temperature, and pH on the removal effect. The removal rates of four MPs were 54.10-94.17%, and the maximum adsorption capacities of FeO@SiO@MIL-53(Al) that can be adsorbed were 10511.45-44390.24 mg g. Notably, the material can effectively magnetize and remove MPs from liquid food containing alcohol with highest efficiency of 97.10 ± 1.21%. Potential adsorption mechanisms were analyzed using kinetic, isothermal, and thermodynamic models, and electrostatic attraction and hydrogen bonding were found to play a dominant role in the adsorption process. In addition, not only can FeO@SiO@MIL-53(Al) be reused up to five times to maintain high removal rates, but it can also be used in food systems. Therefore, FeO@SiO@MIL-53(Al) not only has the advantages of ease of use and stability, but also can efficiently and quickly magnetize and remove many common MPs in more complex matrices such as food.