FABRICATION OF A BIMETALLIC MOF NANOCOMPOSITE FOR ELECTROCHEMICAL SENSING OF TOXIC LEAD IONS IN AQUEOUS ENVIRONMENTS
DOI:
https://doi.org/10.71000/h04tz988Keywords:
Electrochemical techniques, Environmental monitoring, FeCoMOF/PANI-NH₂ composite, Heavy metal ions, Lead detection, Metal–organic frameworks, , PolyanilineAbstract
Background: The contamination of water sources with heavy metals, particularly lead (Pb²⁺), poses a serious global health hazard due to their bioaccumulation and neurotoxic effects. According to the World Health Organization (WHO), the permissible limit of lead in drinking water is 10 µg/L. Exposure beyond this threshold can lead to neurological, renal, and cardiovascular complications. Hence, there is an urgent need for a rapid, sensitive, and cost-effective detection method capable of identifying trace concentrations of heavy metal ions in environmental water samples.
Objective: This study aimed to synthesize and evaluate a bimetallic iron–cobalt metal–organic framework integrated with amine-functionalized polyaniline (FeCoMOF/PANI-NH₂) as a novel electrochemical sensor for the detection of Pb²⁺ ions in aqueous media.
Methods: The FeCoMOF/PANI-NH₂ composite was synthesized through a green, microwave-assisted method and structurally characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The composite material was immobilized on a glassy carbon electrode (GCE) using the drop-casting technique. Electrochemical analyses, including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV), were conducted in 0.1 M KCl containing 5 mM [Fe(CN)₆]³⁻/⁴⁻ at a scan rate of 50 mV/s.
Results: FTIR confirmed the presence of N–H (3500 cm⁻¹), O–H (3400 cm⁻¹), and M–O (600 cm⁻¹) bonds, verifying composite formation. The XRD spectrum revealed semi-crystalline peaks typical of PANI and sharp reflections characteristic of FeCoMOF. SEM micrographs showed a porous, agglomerated morphology conducive to ion diffusion. The modified GCE exhibited a 9.5-fold higher peak current response compared to the bare electrode. EIS revealed a threefold reduction in charge transfer resistance (Rct), while DPV results displayed a linear response between 2–10 µM Pb²⁺, achieving a detection limit of 0.03 µM, significantly below the WHO threshold.
Conclusion: The FeCoMOF/PANI-NH₂ composite demonstrated excellent electrochemical performance, high sensitivity, and long-term stability, confirming its potential as an eco-friendly, cost-effective sensor for real-time detection of lead and other heavy metal ions in environmental water monitoring.
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Copyright (c) 2025 Muhammad Ashraf, Zakir Hussain, Sadaqat Hakeem, Syed Amjad Hussain (Author)
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