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.