Effect of incorporating cellulose nanocrystals into ZnO/PVA nanocomposite for the production of electrochemical sensor to detect cadmium in water

Abstract

Nanocrystalline cellulose is observed to have excellent absorption benefits due to its low cost, biodegradability, and great biocompatibility. The existence of high content of hydroxyl group and large surface area ensures easy modification process. Therefore, changes were implemented to improve the capacity of heavy metal ions for adsorption with the expectation of developing a highly beneficial method of detecting the presence of harmful metal ions capable of harming all living organisms. In this study, cellulose nanocrystals (CNCs) were incorporated into the ZnO/PVA nanocomposites to improve their ability to adsorb metal ions. In the process of analysis, Glassy Carbon Electrode component used ZnO/PVA/CNC as the working material for the electrode. Moreover, X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Photoluminescence, UV–Vis, and I-V spectroscopy were used to analyze the nanocomposites. The results showed that the addition of CNCs enhanced the optical, mechanical, and electrical properties of the ZnO/PVA. Electrochemical measurements using cyclic voltammetry (CV) and square wave voltammetry (SWV) were carried out with varying Cd concentrations. The modified electrode showed enhanced redox activity and a significant increase in peak current response compared to ZnO/PVA without CNC. The sensor demonstrated a linear response toward Cd in the range of 0–80 ppm, with a limit of detection (LOD) of 12.07 ppm. Although the achieved LOD remains above the thresholds required for drinking water safety by regulatory bodies like the WHO, the results underscore the sensor's potential as a foundational platform for further optimization. This study highlights a proof-of-concept application for cadmium detection, particularly relevant in the context of industrial wastewater monitoring.