Comparative Evaluation of Water Hyacinth-Derived Biomass, Biochar, and Nanobiochar for Environmental Remediation: A Review.

Eichhornia crassipes (water hyacinth) is an invasive aquatic macrophyte whose lignocellulosic biomass poses environmental challenges while offering valorization potential. This review examines the thermochemical conversion of water hyacinth into biomass, biochar, and nanobiochar, covering production pathways, process parameters, and remediation performance. High cellulose and hemicellulose content, combined with mineral bioaccumulation, supports efficient pyrolysis, with temperature and residence time governing surface area, pore architecture, and material stability. Studies demonstrate the effective removal of heavy metals, nutrients, dyes, and organic contaminants using water hyacinth-derived biomass, biochar, and nanobiochar, with adsorption performance generally increasing from biomass to biochar and reaching its highest level in nanobiochar because of progressively greater surface area, pore development, and surface reactivity. Ecotoxicological profiling indicates a corresponding increase in potential toxicity from biomass to biochar and nanobiochar, highlighting the need for precautionary deployment and comprehensive risk assessment before field-scale applications. Collectively, biochar stands out in terms of adsorption performance, low toxicity, and economic feasibility.