Zero-Valent Iron Nanoparticles Supported on Biomass-Derived Porous Carbon for Simultaneous Detection of Cd²⁺ and Pb²⁺

A green and efficient electrochemical sensor for simultaneous detection of cadmium (Cd) and lead (Pb) heavy-metal ions is proposed in this work. For this aim, biomass-derived porous carbon (BPC) along with nanoscale zero-valent iron (nZVI) nanoparticles have been used to modify glassy carbon electrodes (GCE). The carbon substrate herein was obtained from abundant marine biomass, Posidonia oceanica. The nZVI particles were in situ reduced on BPC by combining the conventional liquid-phase reduction method of ferric chloride with the impregnating process. Physicochemical and electroanalytical investigations were established by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherm, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS), all suggesting that the nZVI particles were successfully anchored and uniformly dispersed on the carbon substrate, and the synergistic effect between the BPC and nZVI properties uplifts the electrocatalytic ability of the modified electrode nZVI-BPC/GCE. The as-fabricated electrode was then assessed and evaluated for the simultaneous detection of Cd2+ and Pb2+ in an aqueous buffered solution containing acetate using square-wave stripping voltammetry (SWSV). Experimental conditions and parameters such as the effect of electrolyte pH, deposition potential, and deposition time for sensing target ions were optimized. Results demonstrated that the sensing electrode exhibited a linear detection range of 2.0–50 μg/L for both metal ions, and detection limits of 0.1926 and 0.2082 μg/L were recorded for Cd2+ and Pb2+, respectively. Moreover, drinking water samples were further analyzed for the practical testing of the developed sensor, where it also revealed adequate detection performances.