EDTA-functionalized iron oxide nanoparticles: enhanced adsorptive removal of toxic elements from water

Abstract Iron-based nanomaterials are promising adsorbents for water treatment because of their low toxicity, abundance, and affordability. In this study, iron oxide nanoparticles (IONPs) and EDTA-functionalized IONPs were synthesized using guava leaf extract through a precipitation method and evaluated for removing hexavalent chromium (Cr 6+ ) and divalent lead (Pb 2+ ) ions from water. Structural and surface analyses confirmed successful fabrication: XRD showed crystallite sizes of 17.80 nm (bare) and 21.60 nm (functionalized); FTIR identified biogenic functional groups; SEM revealed porous morphology, with higher zeta potential (−30.2 mV ± 4.6) for functionalized particles, and VSM indicated strong magnetization (87.4 emu/g) for bare IONPs. Batch adsorption experiments revealed optimal removal of Pb 2+ at pH 4 and Cr 6+ at pH 2. The adsorption kinetics followed a pseudo-second-order model, and equilibrium data fitted well to the Langmuir model ( R 2 = 0.99), confirming monolayer chemisorption with maximum adsorption capacities of 53.56 mg/g (Cr 6+ ) and 24.56 mg/g (Pb 2+ ). Reusability retained 88 % for Pb 2+ and 76 % for Cr 6+ after two cycles. These results demonstrate that EDTA-functionalized, green-synthesized IONPs are effective, sustainable, and reusable nano-adsorbents for removing toxic elements from contaminated water, providing a scalable pathway for environmental nanotech applications.