Author: G. Sudha

DOI: http://doi.org/10.31788/RJC.2026.1939759

Coal fly ash-derived NaX zeolite-supported cerium oxide (CeO2/Zeo-NaX) was developed as an efficient visiblelight photocatalyst for methylene blue degradation in aqueous solution. Coal fly ash, an abundant aluminosilicateindustrial waste, was first converted to NaX zeolite through alkaline hydrothermal synthesis and then functionalizedwith nanoscale CeO2 to enhance light harvesting and redox activity. The composite was characterised by FTIR, PXRD, SEM-EDX, nitrogen adsorption–desorption, and UV–Vis diffuse reflectance spectroscopy, confirmingzeolite formation, successful CeO2 incorporation, increased surface area, and band gap narrowing into the visibleregion. Under visible-light irradiation, CeO2/Zeo-NaX exhibited superior photocatalytic performance towardmethylene blue, achieving more than 94% degradation at neutral pH under optimised catalyst dosage, dyeconcentration, and irradiation time. Kinetic analysis revealed pseudo-first-order behaviour with a rate constant comparable to or better than many reported photocatalytic systems, which is attributed to synergistic effectsbetween CeO2 nanoparticles and the porous zeolite framework that promote efficient charge separation and reactiveoxygen species generation. The photocatalyst also showed good structural stability and recyclability with onlyamarginal loss in activity over repeated cycles, highlighting its potential as a cost-effective and sustainable material for treating dye-contaminated industrial wastewater while valorising coal fly ash within a circular economyframework. The work contributes to SDG-6 (Clean Water and Sanitation) by combining wastewater treatment withbeneficial reuse of coal fly ash. Its significance lies in offering a low-cost, waste-derived photocatalyst strategythat can support future studies on real industrial effluents, scale-up, catalyst regeneration, and circular-economytreatment systems.

Keywords: Waste-to-Resource Transformation, Nax Zeolite Synthesis, Cerium Oxide Nanoparticles, MethyleneBlue Dye, Visible-Light Photocatalysis, Advanced Oxidation Processes.