Biosynthesis of MgFe₂O₄ Nanoparticles Using Plant Extract for Efficient Lead and Mercury Removal from Water:...

Heavy metal contamination in water poses severe environmental and health challenges, creating an urgent need for sustainable remediation strategies. In this study, magnesium ferrite (MgFe₂O₄) nanoparticles were biosynthesized using natural plant extracts and explored as bioadsorbents for the removal of Pb²⁺ and Hg²⁺ from wastewater. The nanoparticles were thoroughly characterized by SEM, FTIR, and XRD, confirming the formation of well-defined spinel structures (∼3.77 nm) and the presence of hydroxyl and cyano groups as active adsorption sites. Batch adsorption experiments demonstrated high removal efficiencies, with maximum capacities of 94.85 mg/g for Pb²⁺ and 97.37 mg/g for Hg²⁺, best described by the Langmuir isotherm. Kinetic analysis indicated pseudo-second-order behavior, suggesting chemisorption-driven mechanisms. Complementary DFT calculations revealed strong electronic interactions between the metal ions and the MgFe₂O₄ surface, supporting the experimental findings. Additionally, the nanoparticles retained their adsorption performance over five reuse cycles, highlighting their stability and cost-effectiveness. These results position biosynthesized MgFe₂O₄ nanoparticles as promising, sustainable materials for heavy metal remediation in water treatment applications.