Medicinal Plant-Mediated Nanoparticles for Sustainable Water Treatment: Mechanisms, Applications and Safety

Abstract

Medicinal and aromatic plant (MAP)-mediated nanoparticles are increasingly proposed as sustainable materials for water treatment, yet their translational value depends on more than green synthesis feasibility. This review critically evaluates how MAP-derived phenolics, flavonoids, terpenoids, alkaloids, polysaccharides, proteins, and other metabolites influence nanoparticle nucleation, capping, surface chemistry, colloidal stability, and environmental performance. The discussion integrates evidence across Ag, Au, ZnO, TiO 2 , iron oxide, and CeO 2 systems used for potentially toxic element adsorption, photocatalytic degradation of organic pollutants, antimicrobial disinfection, and membrane enhancement. Unlike descriptive reviews that focus mainly on synthesis routes, this article emphasizes mechanistic uncertainty, extract variability, minimum characterization, ion release, reusability, leaching, and ecotoxicological validation. Current evidence shows promising laboratory performance but remains limited by inconsistent extract standardization, incomplete nanoparticle characterization, reliance on model pollutants, weak real-wastewater validation, and scarce life-cycle assessment. Future progress requires metabolite-informed synthesis, comparative performance reporting, simulated and real wastewater testing, immobilized or recoverable nanoparticle formats, standardized ecotoxicity assays, and circular end-of-life strategies. A phased roadmap is proposed to move MAP-mediated nanoparticles from proof-of-concept synthesis toward safer, reproducible, and scalable water treatment technologies.