Simultaneous Electrochemical Detection of Pb and Cd by Carbon Paste Electrodes Modified by Activated Clay

Activated carbon based paste electrodes for the simultaneous and effective detection of divalent cadmium and lead ions in wastewater

Heavy metals (HM) have gained significant attention in terms of regular monitoring and detection owing to their toxicity, non-biodegradability, and persistence. Current techniques for detecting HM are expensive, cumbersome, and require sophisticated instruments and skilled labour. Hence, developing cheap, rapid, energy-efficient, and accurate sensors is imperative and electrochemical techniques have emerged as promising tools. The current study involves the fabrication of an electrochemical sensor for the concurrent detection of lead (Pb2+) and cadmium (Cd2+) ions using modified carbon paste electrodes (mCPE). Activated carbon (AC) with a BET surface area of 1118 m2 g-1 was obtained by chemical activation and thermal treatment of the waste rubberwood sawdust. AC-Graphite, AC-Reduced Graphene Oxide (RGO), and AC-RGO-Chitosan were the types of mCPEs that were utilised. The electrochemical behaviours and effects of pH, concentration, and scan rate were studied using Cyclic voltammetry (CV). Studies on detection were conducted using CV and linear sweep voltammetry. Although all the 3 mCPEs detected Cd2+ and Pb2+ in the simulated wastewater, the CPE with RGO and AC could detect Cd2+ as low as 10.91 µg L-1 and Pb2+ as low as 14.01 µg L-1. The work explored the possibility of using AC as a potential sustainable substitute for graphite in CPE.

Preparation of a Carbon paste electrode with Active materials for the detection of Tetracycline

The Electrochemical sensor based on carbon-clay paste electrode (CCPE) was constructed for sensitive determination of Tetracycline (Tc). The mineralogical composition, morphology, structure and performance of CCPE were characterized using X-ray diffraction powder, Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Cyclic Voltammetry analysis. The CCPE is constituted of two types of clay having the ratio 1/1 and 2/1 characteristic of kaolinite and montmorillonite clay respectively. Its porous structure is ascribed to the presence of graphite. The CCPE exhibited a good electrocatalytic activity towards the oxidation of Tc. The electrochemical kinetics and mechanism of Tc were proposed, showing that Tc electrocatalytic oxidation reaction was controlled by diffusion process and took place in three steps. A low concentration of Tc was detected by amperometry with the linear ranges of 0.5μM-0.8 μM (R2 = 0.98), the sensitivity was 8.01 μA/μM.cm2, the limit of detection and quantification were 5.16x10-3μM(S/N = 3) and 1.72x10-2μM respectively. Thus, the proposed electrode provides a promising and prospective CCPE sensing platform for the detection of Tc in the environment.