New foam filter achieves high microplastic removal rates in initial testing

by Justin Jackson , Phys.org

 DECEMBER 9, 2024 

Morphology of cotton fibers. Photographs and SEM images of cotton fibers (a) (b) before

 and (c) (d) after dispersion. Cotton are micron-sized fiber bundles assembled from

 nanofibers, which could be stripped and uniformly dispersed in water after simple 

mechanical homogenization. Credit: Wu et al., Science Advances 10, eadn8662 (2024)

Wuhan University-led research is reporting the development of a revivable self-assembled supramolecular biomass fibrous framework (a novel foam filter) that efficiently removes microplastics from complex aquatic environments.

Plastic waste is a growing global concern due to significant levels of microplastic pollution circulating in soil and waterways and accumulating in the environment, food webs and human tissues. There are no conventional methods for removing microplastics, and developing strategies to handle diverse particle sizes and chemistries is an engineering challenge.

Researchers have been looking for affordable, sustainable materials capable of universal microplastic adsorption. Most existing approaches involve expensive or difficult-to-recover adsorbents, fail under certain environmental conditions, or only target a narrow range of microplastic types.

In a study, "Revivable self-assembled supramolecular biomass fibrous framework for efficient microplastic removal," published in Science Advances, researchers detail the invention of a fabricated foam that relies solely on hydrogen bonding between protonated chitin nanofiber sheets and cellulose fibers.

Experiments measured adsorption capacity under multiple environmental conditions and across various microplastics: polystyrene, polymethyl methacrylate, polypropylene, and polyethylene terephthalate. Results showed that the foam performed consistently even after repeated use.

Removal efficiencies of up to 98.0 to 99.9% were recorded in water samples and sustained removal rates of 95.1% to 98.1% over multiple cycles. Performance tests demonstrated the foam's rapid adsorption kinetics, reaching equilibrium within 24 hours. Adsorption efficiency remained high across a range of microplastic types and sizes, from 100-nanometer polystyrene microspheres to 3-micron secondary microplastics.

Computational analyses revealed that the adsorption mechanism included physical interception, electrostatic attraction, and multiple intermolecular interactions, such as hydrogen bonding and van der Waals forces.

The researchers emphasize the scalability and environmental adaptability of the foam, its recyclability in organic solvents and its stability under various water conditions.

By integrating cost-effective and sustainable raw materials with a simple fabrication method, the solution hopes to provide a viable strategy for addressing the growing problem of microplastic pollution with practical advantages for large-scale microplastic remediation.

More information: Yang Wu et al, Revivable self-assembled supramolecular biomass fibrous framework for efficient microplastic removal, Science Advances (2024). DOI: 10.1126/sciadv.adn8662

Journal information: Science Advances 

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