Innovatively-synthesized CeO2/ZnO photocatalysts by sono-photochemical deposition: catalyst characterization and effect of operational parameters on high efficient dye removal

CeO2/ZnO with varied Ce4+ mass ratios was synthesized as a stable and reusable photocatalyst using a sono-photochemical process in which CeO2 crystals were formed and precipitated on the porous surface of ZnO nanosheets that had been pre-synthesized using the urea hydrolysis method. The synthesized photocatalysts were characterized through XRD, FTIR, BET, FE-SEM, and TEM techniques. The effects of light and ultrasonic irradiation on the removal of methylene blue (MB) as a contaminant component from deionized (DI) water were examined and the concentration of MB residue was measured using an UV-Vis spectroscopy after the treatment operation. The performance of the photocatalytic degradation was evaluated using a variety of operating parameters including catalyst composition (0-0.70 wt% Ce), initial dye concentration (10-30 ppm), catalyst loading (0.20-1.50 gr L-1), aeration by air flow (0-3.50 L min(-1)), pH (3-9.70), and also ultrasonic irradiation (80 kHz and 60 W). Results demonstrate that when the CeO2/ZnO with Ce/Zn mass ratio of 3 was employed instead of ZnO alone, the time of complete photocatalytic degradation lowered by almost 20%. Additionally, when the real water collected from Doroodzan dam, Fars, Iran with a total TDS of 540 ppm polluted with 20 ppm MB was treated with CeO2/ZnO (0.30 wt% Ce) nanosheets, MB was completely degraded after 8 min of the photocatalytic reaction. Furthermore, the ZCe3 could be used for the degradation process at least for 5 cycles with only a 12% reduction in MB degradation efficiency.

Automated summary

CeO2/ZnO photocatalyst was synthesized using a sono-photochemical process and showed excellent degradation performance in removing methylene blue from water. The synthesized catalyst exhibited stable and reusable properties, with only a slight decrease in efficiency after multiple cycles.