Waste-to-sensor: high-sensitivity detection of heavy metals in water using Arc-ferrite/N-rGO nanocomposites from industrial and electronic waste

Abstract The escalating global crises of hazardous waste accumulation and heavy metal contamination demand innovative solutions that simultaneously address environmental remediation and analytical sensing needs. This study presents a sustainable electrochemical platform fabricated from industrial and electronic waste streams for the high-performance detection of notorious heavy metals. Herein, we repurposed arc furnace dust into ferrite nanoparticles and converted spent battery graphite into highly conductive nitrogen-doped reduced graphene oxide (N-rGO) through controlled synthesis processes. The resulting Arc-ferrite/N-rGO nanocomposite was integrated into a carbon paste electrode, demonstrating exceptional electrochemical performance with a 3.5-fold increase in faradaic current and significantly improved electron transfer kinetics compared to bare electrodes. Through comprehensive optimization of differential pulse voltammetry parameters, the optimal conditions were established as follows: an acetate-KCl buffer (pH 4.5), a deposition potential of -1.1 V, a scan rate of 50 mV/s, and a 180 s accumulation time. The sensor achieved remarkable analytical performance for simultaneous detection of cadmium (II), lead (II), and mercury (II) with detection limits of 1.01 – 1.13 ppb, well below WHO guidelines for drinking water. Excellent linearity (R² > 0.995) across a 10.0 – 150.0 ppb concentration range and superior selectivity against a 100-fold excess of eleven common interfering cations demonstrated the sensor’s robustness for real-world applications. The sensor enabled the simultaneous detection of Pb²⁺, Cd²⁺, and Hg²⁺ in industrial wastewater, with results cross-validated by microwave plasma atomic emission spectroscopy. This work establishes a powerful circular economy paradigm, transforming environmental liabilities into valuable analytical assets while addressing the dual challenges of waste management and environmental monitoring. The Arc-ferrite/N-rGO sensor represents a scalable, economically viable, and environmentally responsible solution for next-generation heavy metal detection systems.