Nanosensor for the detection of eosin yellow and its photocatalytic degradation using phytosynthesized cerium oxide nanoparticles

Abstract

A substantial rise in pollution due to population growth, industrialization, and urbanization has led to water contamination over the past few years, especially in developing countries. Dye-loaded effluents are often discharged into water reservoirs without any treatment, posing a significant threat to the sustainability of the environment and public health. Hence, it is imperative that researchers explore methods to effectively detect and eliminate dyes from waterways and suggest tangible solutions. With this consideration, the current work presents an efficient, cost-effective, eco-friendly, and sustainable approach for the detection of water pollutant (eosin yellow: EY) and its elimination from water. The voltammetric detection of EY was carried out on a transducer fabricated with carboxyl-functionalized multiwalled carbon nanotubes, while its removal was carried out using green-synthesized cerium oxide nanoparticles (CeO₂ NPs). Under optimized conditions, the designed sensor detected EY up to a 1.24 nM limit of detection. CeO₂ NPs were prepared using Cassia fistula leaves for the photocatalytic removal of EY from wastewater. The phytosynthesized CeO₂ NPs were analyzed by X-ray diffraction analysis, photoluminescence spectroscopy, UV-visible spectroscopy, differential scanning calorimetry, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. These synthesized CeO₂ NPs having a band gap of 3.24 eV were applied for the photocatalytic breakdown of EY under direct sunlight. Results revealed 99% removal of EY by CeO₂ NPs from wastewater of pH 5. The findings of the current work emphasize the significance of nanosensor and nanomaterials-based photocatalysis for the detection of water contaminants and for devising a sustainable and environmentally benign remedial plan for water purification.