CeO2 particles were synthesized via a hydrothermal method to investigate the influenceof precursor molarity and reaction time on their structural, optical, and adsorption characteristics. Ce(NO3)3·6H2O served as the cerium source, while PVP and Triton X-100acted as surfactants to regulate nucleation and particle growth. XRD and Raman analysesconfirmed the formation of single-phase cubic fluorite CeO2, whereas FTIR spectra verifiedthe presence of Ce–O bonding. SEM observations revealed that a decreasing precursormolarity led to smaller and more uniform particles, while prolonged reaction times enhanced crystallinity. UV–Vis DRS and XPS analyses indicated that both the band gap(3.06–3.12 eV) and the Ce3+/Ce4+ ratio were governed by oxygen vacancies, demonstrating defect-mediated redox behavior. Adsorption studies using methyl orange (MO) dye followed pseudo-second-order kinetics (R2 > 0.99), indicating chemisorption as the dominant mechanism. The CP1-8 sample exhibited the highest dye removal efficiency (87%) under acidic conditions (pH < pHPZC). These findings demonstrate that controlled hydrothermal synthesis enables precise tuning of CeO2 morphology, defect density, and surface chemistry, yielding efficient adsorbent materials for environmental remediation applications.
Sargin et al. (Sat,) studied this question.