Simultaneous detection of Lead and Cadmium using a composite of Zeolite Imidazole Framework and Reduced Graphene Oxide (ZIF-67/rGO) via electrochemical approach

Abstract

Present work reports the application of a composite of ZIF-67/rGO for the simultaneous detection of traces of lead and cadmium via square wave anodic stripping voltammetry (SWASV) technique. For this, graffoil sheets were modified with synthesized composite for the electrode fabrication [(ZIF-67/rGO)/Graffoil] for its use in sensing studies. The SWASV response of (ZIF-67/rGO)/Graffoil electrode was optimized against deposition potential (-1.0 V) and time (350 s), required for the accumulation of metal ions onto the sensor electrode. The performance of the sensing electrode was then evaluated for lead (Pb<sup>2+</sup>) and cadmium (Cd<sup>2+</sup>) ions at various concentrations. The sensor displayed linear response in a wide concentration range of 5-100 ppb. The peak current of the electrode was found to be shifted towards the higher potential at higher metal ion concentrations. Based on the response measured, the limit of detection (LOD) of the fabricated sensor has been estimated and found to be 5 and 2.93 ppb for Pb<sup>2+</sup> and Cd<sup>2+</sup> ions, respectively. The results obtained revealed good specificity of the proposed sensor towards Pb<sup>2+</sup> and Cd<sup>2+</sup> ions in the co-presence of several other ions. In addition, the sensor exhibited good reproducibility with a relative standard deviation (RSD) of ~2% for both Pb<sup>2+</sup> and Cd<sup>2+</sup> ions.