Synergistic impacts of synthesized zero-valent iron nanoparticles (nZVI) on phytoremediation of lead (Pb) contaminated soil using <i>Tagetus erecta</i> L.

Rapid industrialization, particularly in developing countries, has increased lead (Pb) levels in soil and the environment. This study explores the impacts of nanoscale zero-valent iron (nZVI) on the phytoremediation of Pb using Tagetus erecta L. as a plant. A three-month pot experiment was tested with nZVI amendments of 100, 300, and 500 mg/kg, with a Pb metal concentration of 400 mg/kg. The nZVI was characterized with the FE-SEM (Field Emission Scanning Electron Microscopy), UV-visible spectroscopy, and Zeta Potential Analysis. The study assessed various plant growths, and physiological and biochemical parameters. Characterizations of nZVI revealed that synthesized nZVI were porous in structure, having good stability with a zeta potential of -11.8 mV. Results showed that 500 mg/kg nZVI amendments in Pb treated pots significantly (P<0.05) increased root length by 41%, shoot length by 22 %, relative water content (RWC) by 20%, and total chlorophyll by 25 % as compared to Pb only treatments. The findings also suggested that nZVI amendments resulted in decreased proline content to overcome the Pb stress. The Pb accumulation in T. erecta at 500 mg/kg nZVI amendments was 610 mg/kg in roots and 150 mg/kg in shoots. These were significantly (P<0.05) higher as compared to Pb only treatments. The Pearson correlation analysis revealed that plant growth parameters were negatively correlated with proline content. Hence, the integration of nZVI improved Pb phytoremediation efficiency and mitigated Pb-induced stress in T. erecta.