Chitosan-Modified Loofah Scaffold for Sustainable Microplastic Removal from Water

Sophia Wan-Ting Zhao , Preston Larson, Binbin Weng

The global accumulation of over 400 million tons of plastic waste annually has intensified the growing crisis of micro- and nanoplastic (MNP) contamination in natural and drinking water systems. These particles persist in the environment and act as vectors for toxic pollutants. Existing mitigation strategies often rely on costly synthetic materials or energy-intensive infrastructure, which may generate secondary waste streams and limit accessibility in low-resource settings. Here, we develop a low-cost, biodegradable, easily fabricated filtration platform using chitosan-coated loofah scaffolds designed to remove microplastics across diverse size ranges and morphologies. Mechanically ground polystyrene (PS) particles spanning ~500 nm to several millimeters, including irregular fragments, fibers, and spheres, were used to model realistic morphological heterogeneity. Filtration performance was evaluated under both controlled laboratory conditions and in MNP-spiked environmental pond water to capture interference from naturally occurring organic matter. Removal efficiency was quantified using optical microscopy, while SEM and ATR-FTIR verified coating integrity and characterized interactions between PS particles and the chitosan-modified scaffold. The filters achieved a cumulative MNP removal efficiency exceeding 96%, with up to 98.4% removal across all size bins, and maintained stable performance over four filtration cycles. Importantly, high removal rates persisted in environmental water matrices, demonstrating robustness under realistic conditions. With a material cost of only $0.08 per unit and minimal fabrication requirements, chitosan-modified loofah filters offer a scalable and sustainable approach for microplastic mitigation, especially in regions lacking conventional water-treatment infrastructure, such as rural and developing areas.