Nano-catalytic behavior of CeO nanoparticles in dye adsorption: Synthesis through bio-combustion and assessment of UV-light-driven photo-adsorption of indigo carmine dye.

This study explores the adsorption of indigo carmine dye using bio-combusted cerium oxide nanoparticles (CeO NPs). CeO NPs were synthesized using a bio-combustion method, and then subjected to structural, morphological, and optical characterization for thorough investigation. Structural investigation was carried out using X-ray diffraction (XRD), which revealed a cubic structure with evaluated average crystallite size of 11.55 nm. Later, the same was verified by employing W-H plot (13.57 nm). UV-Vis spectroscopy revealed an effective band gap of 3 eV suited for photocatalytic applications. The metal-oxygen phonon band at 986.32 cm and 871.96 cm is confirmed using Infrared Spectroscopy (FTIR). The morphological analysis was done using Transmission and Scanning Electron Microscopy (TEM and SEM), which revealed well-dispersed, aggregated structure enclosing spherical nanoparticles with an average size of ∼14 nm. The early precursors were validated using EDAX analysis and SEM. Optical characteristics were investigated using photoluminescence (PL), which revealed a large charge transfer band between 360 nm and 435 nm. The dye removal efficiency of CeO NPs was evaluated against Indigo Carmine dye using UV light. The results showed that the significantly adsorption, with more than 70 % removed after 150 min. Kinetic experiments revealed that the depreciation occurred via a pseudo-first-order reaction process. Furthermore, the impacts of certain factors such as dye dosage, pH, reusability, and scavenger on adsorption rate were explored and shown to be effective values for the adsorption process. This study emphasizes the potential of CeO NPs as excellent photocatalysts for environmental remediation, especially in dye removal applications.