Eco-friendly synthesis of nZVI for water remediation: latest developments and environmental applications

This review discusses recent advances in the green synthesis of nanoscale zero-valent iron (nZVI), with emphasis on plant-derived materials as sustainable reducing and stabilizing agents. A wide range of plant extracts obtained from leaves, seeds, peels, and other biomass sources have been employed to generate nZVI through phytochemical-mediated reduction, offering an eco-friendly alternative to conventional chemical methods. Emerging research demonstrates a clear shift toward bio-inspired and circular synthesis strategies, where polyphenol- and alkaloid-rich extracts enhance particle stability, control size distribution (typically 10-100 nm), and improve reactivity. Moreover, these research strategies have pointed out a notable increase in the reusability of nZVI and have also been directed toward integrating nZVI compounds with natural supports, such as clays, biochar, and agricultural residues, to limit aggregation, increase reusability, and improve performance in complex wastewater matrices. Green-synthesized nZVI has shown broad potential in sustainable remediation, with particle sizes generally ranging from 10 to 80 nm and removal efficiencies of approximately 90% for dyes, heavy metals, and antibiotics under optimized conditions. Supported nZVI composites further demonstrate strong environmental robustness, exhibiting up to 95% reusability over multiple cycles. The novelty of this review lies in its integrated analysis connecting synthesis routes, physicochemical properties, and environmental performance of plant-mediated nZVI, addressing gaps in earlier literature that largely overlooked these correlations. Finally, the review critically evaluates the scalability, stability, and ecological impacts of green-synthesized nZVI and outlines future research needs for improving reproducibility and advancing practical applications in real-world water treatment systems.