Removal and Degradation of Microplastics Using the Magnetic and Nanozyme Activities of Bare Iron Oxide Nanoaggregates

Removal and degradation of microplastics are often carried out separately. In this work, hydrophilic bare Fe₃ O₄ nanoaggregates allowed efficient removal of the most common microplastics including high-density polyethylene, polypropylene, polyvinyl chloride, polystyrene, and polyethylene terephthalate. Full extraction was achieved using Fe₃ O₄ at 1 % of the mass of microplastics. Hydrogen bonding is the main force for the adsorption of Fe₃ O₄ . Unlike the more commonly used hydrophobically modified Fe₃ O₄ nanoparticles, the bare Fe₃ O₄ benefitted from the peroxidase-like activity of its exposed surface, enabling further catalytic degradation of microplastics with nearly 100 % efficiency and easy recovery of the Fe₃ O₄ .