Waste-derived zinc oxide nanoparticles from water hyacinth: Green synthesis, characterization, and multifunctional activities

The rapid spread of Pontederia crassipes (water hyacinth) causes severe ecological and economic challenges in freshwater ecosystems, including biodiversity loss, eutrophication, and disruption of water utilization. This study explores the waste valorization of this invasive biomass for the green synthesis of zinc oxide nanoparticles (ZnONPs), thereby addressing both environmental remediation and sustainable production. Aqueous extracts from leaf, flower, and root parts of P. crassipes were employed as bioreductants and stabilizing agents in nanoparticle fabrication. The synthesized ZnONPs were systematically characterized (UV–Vis, FTIR, XRD, SEM/TEM, zeta potential, and EDX) and evaluated for multifunctional applications, including antioxidant, antibacterial, and photocatalytic performance. Among the tested samples, flower-derived ZnONPs demonstrated the most favorable features: high yield, uniform quasi-spherical morphology, enhanced colloidal stability, and superior multifunctional bioactivities. Importantly, ZnONPs achieved up to 70.54% degradation of methylene blue dye under visible light, confirming their strong potential for wastewater treatment. This dual-benefit approach not only mitigates the ecological burden of invasive water hyacinth but also generates high-value nanomaterials for cleaner production applications. The findings highlight a circular bioeconomy pathway in which problematic biomass is transformed into sustainable nanomaterials, thereby mitigating pollution and advancing environmentally benign nanotechnology.