Preparation of a CeO2/γ-Al2O3 composite and its catalytic degradation performance
CeO2/γ-Al2O3 composite catalyst has been prepared using CeO2 as an active component and γ-Al2O3 as a support to remove dye from wastewater by catalytic degradation. The catalytic performance of the CeO2/γ-Al2O3 sample for the degradation of methylene blue is studied under visible light irradiation. The results show the presence of γ-Al2O3 and CeO2 with a cubic fluorite structure in the CeO2/γ-Al2O3 samples synthesized at 550°C. Small CeO2/γ-Al2O3 particle and a good dispersion of CeO2 are achieved with loading of CeO2. The loading of CeO2 on γ-Al2O3 also increases the total pore volume and pore diameter, which results in a high specific surface area of 132.03 m2/g, a total pore volume of 0.74 cm3/g, and a mean pore diameter of 22.54 nm. The photocatalytic degradation efficiency of methylene blue by the CeO2/γ-Al2O3 catalyst is higher than those of CeO2 and γ-Al2O3. Under the same conditions the CeO2/γ-Al2O3 catalyst achieves 98.36% degradation at 80 min, higher 5.0% and 11.9% degradation than CeO2 and γ-Al2O3, respectively. The high efficiency is attributed to promotion of the structural and textural performance of the CeO2/γ-Al2O3 catalyst by synergistic interaction between CeO2 and γ-Al2O3. These performances promote a larger surface area, higher content of acid sites, more •OH radicals and higher redox properties of the catalyst. The catalytic reaction kinetics could be fitted by the heterogeneous Langmuir-Hinshelwood model and the pseudo-first order rated constant for kapp is 17.5×10−2, which is 1.33 and 2.5 times as big as those of CeO2 and γ-Al2O3, respectively. CeO2/γ-Al2O3 catalyst suggests promising application for practical dye pollutant treatment.
Composite catalyst; CeO2/γ-Al2O3; Methylene blue; Catalytic degradation; Wastewater treatment
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