Efficient Adsorption and Photocatalytic Degradation of Acid Orange 7 Dye Using Ethylene Glycol‐Assisted CeO ₂ Nanoparticles

ABSTRACT The efficient removal of organic dyes is essential for wastewater remediation. In this study, we report the synthesis of cerium oxide (CeO 2 ) nanoparticles via alkaline precipitation, using ethylene glycol (EG) as a complexing agent to tailor structural and surface properties. XRD and Raman analyses confirmed a fluorite‐type cubic phase, with a decrease in average particle size from 15 to 9 nm upon EG addition. The surface area, Ce 4+ /Ce 3+ ratio, surface hydroxyl groups and the concentration of oxygen vacancies were found to be directly influenced by the use of EG. CeO 2 nanoparticles predominantly exhibited a spherical morphology along with a few nanorods. The EG‐assisted CeO 2 exhibited superior efficiency for the adsorption and photocatalytic degradation of acid orange 7 (AO7) under UV radiation. This enhanced performance is attributed to the synergistic effects of increased active sites and surface charge. Radical scavenging experiments identified radicals as the primary active species, with •OH radicals and holes playing secondary roles. CeO 2 catalyst could be reused up to four cycles without significant loss of activity. These findings highlight that EG‐assisted synthesis effectively tailors CeO 2 properties to improve its performance in remediation of emerging pollutants.