Sustainable valorization of water hyacinth-derived lignocellulose towards functional applications

Invasive plant species like water hyacinth (WH) are often problematic due to their rapid growth, forming dense colonies that deplete nutrients and reduce oxygen levels in water bodies. However, the green valorization of this aquatic weed and its transformation into valuable products could help address the interconnected challenges of pollution, climate change, and biodiversity loss. In this study, we utilized WH - a sustainable, low-cost, and abundant biomass-to develop eco-friendly biopolymers as sustainable alternatives to synthetic plastics. Unlike kraft pulping, our approach uses a highly adaptable and recyclable green deep eutectic solvent (DES) to break down WH into a viscous lignocellulose slurry. By casting this slurry, we created bioplastics with excellent physical and mechanical properties. The resulting biopolymer displays a high tensile strength of 101.8 MPa, outperforming kraft paper and surpassing common bioplastics like PLA and PHA, demonstrating superior structural performance. These biopolymers can be easily recycled at the end of their life by mechanical disintegration in water, allowing the lignocellulose slurry to be reused. Unlike non-biodegradable synthetic plastics, our bioplastics can naturally biodegrade in the soil, exemplifying a desirable closed-loop cycle. The biopolymer also retained high antioxidant activity of 90.2%, making it suitable for applications requiring oxidative stability. This work advances eco-friendly material science by promoting resource recovery, reducing plastic pollution, and offering a method to control the spread of WH. In the future, WH biopolymers could replace commonly used petrochemical plastics in sustainable, multifunctional applications such as agricultural mulching films, food packaging, and foams.