Selective and sensitive electrochemical determination of Pb 2+ based on highly adsorptive WO x –ethylenediamine nanowires

Electrochemical detection of heavy metal ions in water

Heavy metal ions are one of the main sources of water pollution. Most heavy metal ions are carcinogens that pose a threat to both ecological balance and human health. With the increasing demand for heavy metal detection, electrochemical detection is favorable due to its high sensitivity and efficiency. Here, after discussing the pollution sources and toxicities of Hg(ii), Cd(ii), As(iii), Pb(ii), UO₂(ii), Tl(i), Cr(vi), Ag(i), and Cu(ii), we review a variety of recent electrochemical methods for detecting heavy metal ions. Compared with traditional methods, electrochemical methods are portable, fast, and cost-effective, and they can be adapted to various on-site inspection sites. Our review shows that the electrochemical detection of heavy metal ions is a very promising strategy that has attracted widespread attention and can be applied in agriculture, life science, clinical diagnosis, and analysis.

L-Glutamine-assisted synthesis of ZnO oatmeal-like/silver composites as an electrochemical sensor for Pb2+ detection

We report a green synthesis of oatmeal ZnO/silver composites in the presence of L-glutamine as an electrochemical sensor for Pb²⁺ detection. The synthesis was performed via the direct reduction of Ag⁺ in the presence of L-glutamine in NaOH. X-ray diffraction indicated that the Ag⁺ was completely reduced to metallic Ag. The field emission scanning electron microscopy (FESEM) and energy dispersive X-ray results confirmed an oatmeal-like morphology of the ZnO with the presence of Ag. The FESEM images showed the effect of L-glutamine on the ZnO morphology. The EIS results confirmed a significant decrease in the charge transfer resistance of the modified glassy carbon electrode due to the presence of Ag. From the differential pulse voltammetry results, a linear working range for the concentration of Pb²⁺ between 5 and 6 nM with LOD of 0.078 nM (S/N = 3) was obtained. The sensitivity of the linear segment is 1.42 μA nM^-1 cm^-2. The presence of L-glutamine as the capping agent and stabilizer decreases the size of Ag nanoparticles and prevents the agglomeration of ZnO, respectively. Graphical abstract ᅟ.