Water Hyacinth Cellulose for Polymer Composites and Bioplastics: A Review of Extraction, Formulation and Applications

Petroleum-based plastics generate over 400 million tonnes of waste annually, posing severe ecological threats to terrestrial and aquatic environments. Concurrently, water hyacinth (Eichhornia crassipes, Mart.) infests over 50 countries, disrupting waterways, fisheries, and riparian economies. This review proposes that both challenges can be addressed within a single material strategy: valorizing water hyacinth biomass into cellulose-derived bioplastics, nanocellulose composites, and functional hydrogels. To organize the evidence, the review uses a conceptual Harvest–Extract–Formulate–Deploy (HEFD) scheme that follows the value chain from field harvest through cellulose extraction, composite formulation and crosslinking to end use. The scheme is a structuring device and not a validated model. The review draws on the peer-reviewed literature published between 2018 and 2026 and examines composition, mechanical and thermal performance, synthesis routes, and applications in packaging, agriculture and biomedicine. Water hyacinth is not a plastic in itself but a variable lignocellulosic raw material, and the properties of materials made from it depend mainly on the matrix polymer, filler content, and the interface between the two. Reported tensile strengths are modest and elongation at break is far below that of low-density polyethylene (LDPE), so equivalence with LDPE has not been shown. Mass loss in soil-burial tests ranges from a few percent to near-complete disintegration depending on the formulation, and few studies measure mineralization. Feedstock may be cheap, or even paid for, where removal is publicly funded, but no peer-reviewed techno-economic study has confirmed this advantage. A decentralized small-scale production model is proposed for tropical smallholder settings, and clear gaps remain in life-cycle assessment, standardization, and regulation.