Photocatalytic degradation of methyl orange using CuO/Al 2 O 3 nanocomposite obtained by microwave-assisted thermal decomposition route

Aluminum oxide (Al 2 O 3 ) and copper oxide (CuO) are known to exhibit very exceptional properties including high thermal and chemical properties that promise a wide area of applications. In this paper, we report the microwave -assisted thermal decomposition route to CuO/Al 2 O 3 nanocomposite and its application as a photocatalyst for methyl orange (MO) degradation. Al 2 O 3 was first prepared at different temperatures of 900, 1000, and 1100 degrees C, denoted as Al 2 O 3 (1), Al 2 O 3 (2), and Al 2 O 3 (3). Subsequently, the best temperature (1000 degrees C) was selected for the synthesis of CuO/Al 2 O 3 nanocomposite. XRD analysis confirmed the hexagonal crystal structure for all the Al 2 O 3 and the monoclinic phase for the CuO within the composite. The crystallite sizes of the alumina increased with temperature and a similar growth pattern occurred in the entire samples. Scanning electron microscopy and transmission electron microscopy (SEM and TEM) show clear spherical morphology for all the samples with obvious agglomeration as temperature increases. Optical characterization displayed decreasing band gap energies with increasing temperature, implying size increase due to particle interaction, boundary energy reduction, and grain boundary migration. The photocatalytic performance of the CuO/Al 2 O 3 under visible light was evaluated on methyl orange (MO), and the degradation was studied with some process parameters such as the effect of catalysts dosage and initial concentration of MO. Results showed that the CuO/Al 2 O 3 exhibited about 94.2 % efficiency within 3 h using an optimum dose of 2.0 g/L and an initial MO concentration of 20 mg/L. However, the use of CuO/Al 2 O 3 nanocomposites to remove other organic pollutants could confirm the robustness of this catalyst.