Biogenic MnO₂ nanoparticles for heavy metal removal

This study investigates the biogenic synthesis of manganese dioxide (MnO₂) nanoparticles using aqueous extract of leek (Allium ampeloprasum) leaves as a natural reducing and capping agent, providing an environmentally friendly alternative to chemical synthesis. The biologically derived MnO₂ nanoparticles were applied for the removal of heavy metal ions (Pb²⁺, Cd²⁺, Cr³⁺, and Ni²⁺) from contaminated aqueous media. To enhance bioadsorption efficiency and stability, MnO₂ nanoparticles were immobilized within calcium alginate biopolymer matrices. Comparative analyses demonstrated that the entrapped nanoparticles exhibited superior biosorption performance (96–98% removal efficiency) relative to free nanoparticles or alginate alone. Adsorption equilibrium data were evaluated using the Langmuir and Freundlich isotherm models, indicating strong biosorption affinity and favorable adsorption behavior (R² = 0.99861). The results highlight the potential of green-synthesized, bio-based nanomaterials as efficient, sustainable biosorbents for heavy metal remediation and environmental protection. This approach underscores the integration of biological resources and nanotechnology for eco-compatible bioremediation strategies.