Indian Journal of Chemical Technology, Vol.27, No.3, 235-242, 2020
Preparation of a CeO2/gamma-Al2O3 composite and its catalytic degradation performance
CeO2/gamma-Al2O3 composite catalyst has been prepared using CeO2 as an active component and gamma-Al2O3 as a support to remove dye from wastewater by catalytic degradation. The catalytic performance of the CeO2/gamma-Al2O3 sample for the degradation of methylene blue is studied under visible light irradiation. The results show the presence of gamma-Al2O3 and CeO2 with a cubic fluorite structure in the CeO2/gamma-Al2O3 samples synthesized at 550 degrees C. Small CeO2/gamma-Al2O3 particle and a good dispersion of CeO2 are achieved with loading of CeO2. The loading of CeO2/gamma-Al2O3 also increases the total pore volume and pore diameter, which results in a high specific surface area of 132.03 m(2)/g, a total pore volume of 0.74 cm(3)/g, and a mean pore diameter of 22.54 nm. The photocatalytic degradation efficiency of methylene blue by the CeO2/gamma-Al2O3 catalyst is higher than those of CeO2 and gamma-Al2O3. Under the same conditions the CeO2/gamma-Al2O3 catalyst achieves 98.36% degradation at 80 min, higher 5.0% and 11.9% degradation than CeO2 and gamma-Al2O3, respectively. The high efficiency is attributed to promotion of the structural and textural performance of the CeO2/gamma-Al2O3 catalyst by synergistic interaction between CeO2 and gamma-Al2O3. These performances promote a larger surface area, higher content of acid sites, more center dot 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 k(app) is 17.5 x10(-2), which is 1.33 and 2.5 times as big as those of CeO2 and gamma-Al2O3, respectively. CeO2/gamma-Al2O3 catalyst suggests promising application for practical dye pollutant treatment.