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Capturing nanoplastics through a collagen fibrous membrane with hierarchical functional surfaces
Summary
Scientists have created a filter made from collagen (a natural protein, not plastic) that can capture over 98% of nanoplastics from water—tiny plastic particles too small to see that have been found in our blood and organs. Unlike current plastic-based filters, which are hard to recycle, this collagen membrane is eco-friendly, reusable, and works by chemically grabbing onto plastic particles rather than just blocking them by size, making it a promising step toward cleaner drinking water in the future.
Nanoplastics (NPs) pose a significant threat to ecosystems and human health due to their diminutive size and high potential for bioaccumulation. Most existing membranes for NPs separation, however, are composed of non-biodegradable, petroleum-based polymers that are difficult to recycle. This study introduces the development of an eco-friendly collagen fibrous membrane (CFM) with a hierarchical structure designed for NPs capture, achieved through crosslinking CFM with a polyphenol-Al coordination system (P/Al-CFM). The polyphenol-Al crosslinking significantly enhances collagen fiber dispersion, imparting the membrane with increased porosity, hydrophilicity, mechanical strength, and thermal stability. P/Al-CFM exhibited high removal efficiency (> 98%) and flux (> 4400 L·m·h·bar) for NPs with varying surface charges (PS-COOH and PS-NH), along with excellent resistance to interference from complex water matrices and satisfactory reusability. Furthermore, modulating the crosslinking degree tailors the pore structure, characterized by an increased proportion of pores smaller than 3 μm and a shift in the dominant pore size from approximately 10 μm to 6 μm, which enhances the removal of smaller NPs (e.g., 20 nm) but reduces permeation flux. Mechanistic investigations revealed that NPs capture is driven by a synergistic effect of the hierarchical functional surfaces, involving intra-particle diffusion and multi-site chemisorption, rather than mere size exclusion. This work offers a novel approach for developing high-performance, sustainable bio-based filtration materials.