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

Abstract

Removal and degradation of microplastics are often carried out separately. In this work, hydrophilic bare Fe3O4 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 Fe3O4 at 1 % of the mass of microplastics. Hydrogen bonding is the main force for the adsorption of Fe3O4. Unlike the more commonly used hydrophobically modified Fe3O4 nanoparticles, the bare Fe3O4 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 Fe3O4.

Spherical DNA for Probing Wettability of Microplastics

“…Comparing the Raman spectra of the fresh and soaked PP samples, no apparent changes were observed in the carbonyl (∼1600–1800 cm −1 ) and hydroxyl regions (∼3300–3600 cm –1 ), confirming that only physical changes occurred, leading to increased wettability (Figure C). Oxidation of microplastics can generate surface carbonyl and hydroxyl groups, which can also enhance adsorption on microplastics. ,, Previous studies on the oxidation of microplastics typically used remarkably harsher conditions such as a heating time of 1–90 days and temperatures of 70–120 °C. ,, For example, when PP microplastics were oxidized at 70 °C in the presence of an oxidizing agent (K 2 S 2 O 8 ), after 5 days, the carbonyl peak started to appear in the IR signal . Thus, it was not surprising that our mild wetting conditions did not induce a change in the chemistry of the microplastic surface.…”

“…The size and morphology of the microplastics were then observed using an optical microscope (Figures A,B and S2). While the samples had a broad shape and size distribution (from 20 to 800 μm), they all fulfilled the size requirement of microplastics (<1 mm) …”

Comparison of the peroxidase activities of iron oxide nanozyme with DNAzyme and horseradish peroxidase

“…Small Fe 3 O 4 NPs were synthesized according to our previous method. 35 The other chemicals utilized here were of analytical grade. Hemin was dissolved in dimethyl sulfoxide (DMSO) to prepare a stock solution.…”

Application of Nanozymes in Environmental Monitoring, Management, and Protection

“…Therefore, it is crucial to remove and degrade microplastics in water resources. Hydrophilic bare Fe 3 O 4 nanoaggregates allowed efficient removal of the most common microplastics including high-density polyethylene, polypropylene, polyvinyl chloride, polystyrene, and polyethylene terephthalate [ 177 ]. The bare Fe 3 O 4 nanoaggregates with peroxidase-like activity further catalyzed the degradation of microplastics with nearly 100% efficiency by adsorbing to microplastics via hydrogen bonding ( Figure 8 c).…”

“…( b ) Experimental design and process on NMCMP (NMCMP: nanozyme nanoMn 3 O 4 -coated microbial populations) [ 167 ]. ( c ) Schematic diagram of Fe 3 O 4 nanozyme-catalyzed degradation of microplastics [ 177 ]. Reproduced with permission from ( a ) Ref.…”