Detection of Copper Ions in Seawater Using a Graphitised Multi-Walled Carbon Nanotubes-Copper Ion Carrier Modified Electrode

Abstract

Copper is an essential element in living organisms and is crucial in marine ecosystems. However, excessive concentrations can lead to seawater pollution and pose a risk of toxicity to marine organisms, as it is a heavy metal. In addition, it can enter the human body through the food chain, potentially endangering human health. Consequently, there is increasing focus on the rapid and highly sensitive detection of copper ions (Cu2+). We prepared a graphite carbon electrode modified with graphitised multi-walled carbon nanotubes/copper(II) ion carrier IV (GMWCNT/copper(II) ion carrier IV/glassy carbon electrode (GCE)) using a drop-coating method. Scanning electron microscopy (SEM) analysis revealed that the composite material film possessed a large surface area. Incorporating this composite material significantly enhanced the adsorption capacity for ions on the electrode surface and greatly improved conductivity. Differential pulse anodic stripping voltammetry (DPASV) was employed to quantify copper levels in seawater. Under optimal experimental conditions, a strong linear relationship was observed between the Cu2+ response peak current and its concentration within a range of 50–500 µg L−1, with a correlation coefficient of 0.996. The GMWCNT/copper(II) ion carrier IV/GCE exhibited excellent stability and reproducibility, achieving a low detection limit for Cu2+ at 0.74 µg L−1 when applied to copper detection in seawater. Furthermore, spiked recovery rates ranging from 98.6% to 102.8% demonstrated the method’s high sensitivity, convenient operation, and practical value for real-world applications in detecting Cu2+ levels in seawater.