Phyto-mediated synthesis of magnesium doped iron oxide nanoparticles and its eco-friendly application towards agriculture and environmental remediation

The study investigates the potential of environmentally friendly magnesium-doped nanoparticles derived from Hydrocotyle umbellata leaves, showcasing advantages over commercial counterparts in enhanced seed priming activity and reduced toxicity. The ferric ion reduction is confirmed through Surface Plasmon Resonance (SPR) analysis of Fe₃O₄NPs, revealing distinctive absorption peaks at 400–500 nm in UV–Vis spectra and bandgaps of 1.75 eV for 1% Mg-doped Fe₃O₄, 1.62 eV for 3% Mg-doped Fe₃O₄. A decrease in 3304.98 cm^− 1 was seen in the plant extract peaks analysis, and vibrational peaks at 1361.15 cm^− 1 (Fe₃O₄), 1350.33 cm^− 1 (1% Mg-doped Fe₃O₄) and 1354.14 cm^− 1 (3% Mg-doped Fe₃O₄) validated the synthesis of Fe₃O₄ NPs. Fluorescence spectra exhibit emission peaks corresponding to iron oxide ratios between 780 and 800 nm. Crystal size variations are observed: undoped Fe₃O₄ (42.41 nm), 1% Mg-doped Fe₃O₄ (37.07 nm), and 3% Mg-doped Fe₃O₄ (68.16 nm). Fe-SEM and EDAX mapping confirm the presence of Mg, Fe, and O elements in nanorods and spherical nanoparticles. Thermally stable up to 800 °C, Mg-doped materials show increased magnetic characteristics with saturation magnetization values of 7.25 emu/g for Fe₃O₄ and 22.50 emu/g for Mg-doped Fe₃O₄. XPS analysis reveals elemental composition, while DPPH assays demonstrate enhanced antioxidant function in Mg-doped Fe₃O₄. Raphanus sativus seed analysis indicates varied impacts, and in vitro cytotoxicity studies on Allium cepa roots show no morphological alterations in cell cycle phases. The maximum adsorption capacity of Ni²⁺ ions using Fe₃O₄ Mg-doped Fe₃O₄ and commercial nanoparticles was found to be 98.03 mg/g, 84.74 mg/g and 64.51 mg/g. The heterogeneous chemisorption mechanism and the Freundlich isotherm model best fit the experimental data, underscoring the research’s comprehensive insights into the synthesis, characteristics, and diverse applications of magnesium-doped nanoparticles in nano remediation.