Electrochemical detection of eosin yellow dye and its adsorptive removal from wastewater

Abstract The environmental persistence and toxicity of Eosin Yellow (EY) dye demand sensitive detection and effective remediation approaches. Herein, we report a new dual function approach for the ultra-trace detection and removal of EY using modified glassy carbon electrode (GCE) for detection and employing adsorption method for efficient removal. The electrochemical sensing platform was prepared by modifying GCE with carboxyl-functionalized multiwalled carbon nanotubes (COOH-fMWCNTs) and Fe doped ZnO nanoparticles. The adsorptive removal of EY was carried out using NiCu-layered double hydroxide (NiCu-LDH). Both materials (the electrode modifier and the adsorbent) were successfully synthesized and characterized by XRD, XPS, FESEM, TEM, HR-TEM, EDS, FTIR and UV-Vis analyses, confirming the formation of hexagonal Fe-ZnO and rhombohedral NiCu-LDH exhibiting a nanosheet like morphology. The designed sensor exhibited excellent electrocatalytic activity for EY detection, enabling a wide linear detection range (0.01 µM to 30 µM) with a 0.314 nM limit of detection (LOD). For wastewater remediation from EY, NiCu-LDH was used as adsorbent. This adsorbent harnesses the high surface area and strong adsorption capacity, the porosity and the mechanical strength, resulting in improved dye adsorption and environmental sustainability. This adsorbent achieved rapid equilibrium with the adsorbate EY within 55–60 min and showed maximum adsorption capacity of 71.4 mg.g − 1 in accordance with the Langmuir isotherm model, suggesting monolayer adsorption. The adsorption adhered to pseudo-second order kinetics with optimal performance at pH 6. Collectively, this work presents a detection platform designated as COOH-fMWCNT/Fe-ZnO/GCE based sensor enabling trace-level EY monitoring, while NiCu-LDH as an adsorbent for bulk dye removal, offering a practical solution for water quality management.