Simultaneous Electrochemical Detection of Pb (II) and Cu (II) at Reactive Black Dye/MgAl‐Layered Double Hydroxide Modified Electrode

Environmental pollution by heavy metals such as Cu(II) and Pb(II) is recognized as a major public health issue. Considering that these two heavy metals are generally present simultaneously in the same polluted environments, the development of fast, robust, and cost‐effective analytical tools for their simultaneous quantification is of considerable importance. In this study, a composite material (MgAl‐RB5) obtained by the modification of a MgAl‐layered double hydroxide (LDH) by an anionic dye (Reactive Black 5 (RB5)) was synthesized and used as a glassy carbon electrode modifier, applied for the simultaneous electrochemical detection of Pb(II) and Cu(II). The presence of the dye adsorbed onto the LDH (0.23 mmol g ⁻¹ ) and the affinity of the hybrid material for cationic compounds were highlighted by physicochemical (FTIR, TGA, BET‐specific surface area, and SEM) and electrochemical characterizations. The electrochemical signals of Cu(II) and Pb(II) at the glassy carbon electrode were improved in the presence of MgAl‐RB5 at the electrode surface due to the accumulation of these metal cations through complexation with the immobilized dye molecules. After optimization of some key experimental parameters (pH of the accumulation solution, deposition potential, nature of electrolytic solution, and accumulation times), limits of detection of 5.2 nM (1.08 µg L ⁻¹ ) and 8.1 nM (0.51 µg L ⁻¹ ) were obtained for Pb(II) and Cu(II), respectively, in the concentration range 0.1–8 μM. The sensor displayed good efficiency in several tested environmental samples, confirming tested and confirmed its potential use for the simultaneous detection of Cu(II) and Pb(II) in environmental pollution monitoring.