A review on Biowaste derived nanomaterials for sustainable and multifunctional water purification systems

Purpose This review examines the development of nanomaterials derived from agricultural and industrial biowaste for sustainable water purification, establishing a structure-chemistry-performance framework that clarifies their multifunctional capabilities, practical limitations, and position relative to advanced engineered materials. Methods Recent literature was critically analysed to assess how lignocellulosic and mineral-rich biowaste is transformed into nano-activated carbons and hybrid nanocomposites. Emphasis was placed on activation chemistry (KOH, ZnCl₂, H₃PO₄), thermal processing, and emerging biological routes, evaluating their influence on pore architecture, surface functionality, and interfacial charge behaviour. Comparative benchmarking against metal-organic frameworks, graphene-based materials, doped semiconductor photocatalysts, and engineered biochars was undertaken alongside assessment of environmental safety, leaching risks, energy demand, feedstock variability, and life-cycle impacts. Results Biowaste-derived nanomaterials exhibit tunable hierarchical porosity, chemically active surfaces, and integrated adsorption, photocatalytic, antimicrobial, and magnetic recovery functions when rational activation and hybridisation strategies are applied. Activation conditions directly govern micropore formation, structural ordering, and functional-group incorporation, which are critical to heavy-metal binding and pollutant transformation. Although advanced synthetic materials may demonstrate higher peak performance under controlled conditions, biowaste-derived systems offer a more balanced combination of scalability, regeneration potential, and environmental compatibility. Key challenges remain in feedstock heterogeneity, activation energy requirements, chemical recovery, and long-term metal-carbon stability. Conclusion When engineered through mechanistically informed design rather than empirical precursor selection, biowaste-derived nanomaterials constitute a structurally competitive and economically viable platform for water treatment. Their strength lies in delivering integrated multifunctionality within a circular-economy framework rather than maximising isolated performance metrics. Future progress depends on standardised synthesis, predictive structure–property modelling, green activation strategies, rigorous leaching evaluation, and validation under realistic operating conditions to enable scalable, system-ready deployment in sustainable and decentralised water purification technologies.