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Sustainable tannic acid-based polyurethane foam for enhanced microplastic removal and antibacterial water purification
Summary
Scientists created a new water filter foam by adding tannic acid (a natural compound found in tea and plants) to regular polyurethane foam, which made the filter's pores much smaller and tighter, shrinking them by over 85%. This upgraded foam not only traps tiny plastic particles more effectively but also kills bacteria, cutting bacterial counts in wastewater by over 90%, making it a promising, eco-friendly tool for cleaning up water we might eventually drink or use.
Microplastic (MP) pollution is a critical environmental concern due to its persistence, bioaccumulation, and toxicity. Conventional polyurethane filters, while widely used in water treatment for their porosity and flexibility, suffer from large, non-uniform pores (>60 μm) and lack intrinsic antibacterial properties, limiting their efficiency. To overcome these issues, we developed an eco-friendly, multifunctional polyurethane foam (PUF) incorporating tannic acid (TA), a natural polyphenol. TA provides strong antibacterial and antioxidant activity and functions as a bio-based crosslinker within the polyurethane matrix, enhancing foam stability. Increasing the TA content creates a more robust network structure, thereby decreasing the average pore size by 85.4% (from 65.6 μm to 9.6 μm) and enhancing the removal efficiency for microplastics of various sizes. Furthermore, filtration tests using real wastewater demonstrated a 91.9% reduction in bacterial counts (from 1,215 to 98 CFU mL⁻ 1 ), confirming the antimicrobial efficacy of the material. TA-incorporated PUF achieve simultaneous removal of MP and microorganisms. The reactive incorporation of TA creates uniform pores while preserving the mechanical integrity of conventional polyurethane, making it a promising material for advanced wastewater treatment.