In situ crystallization of ZnAl2O4/ZnO nanocomposite on alumina granule for photocatalytic purification of wastewater

ZnAl2O4/ZnO nanocomposites with different ZnO (20, 30, and 40 mol%) concentrations and coated samples on supports were successfully prepared through combustion synthesis assisted by microwave. Two catalyst supports (alpha-Al2O3 granules and gamma-Al2O3 granules) in the forming of granules were used by sintering. The obtained products after calcination were characterized by X-ray diffraction (XRD), electron microscopy (SEM and TEM), Brunauer-Emmett-Teller (BET), dynamic light scattering (DLS), photoluminescence spectroscopy (PL), and UV-Vis spectroscopy. Samples were studied by degradation of methyl orange (MO) under UV irradiation in a photoreactor to evaluate the photocatalytic performance. Degradation using a ZnAl2O4/ZnO (30 mol%) nanocomposite reached 97.1 %. gamma-Al2O3 granules have demonstrated considerable difference in photocatalytic efficiency compared to alpha-Al2O3 granules. Therefore, the coated granules were able to be employed for the removal of dyes from wastewater, having desirable repeatability and reusability. Our results may initiate large-scale production of coated layers with promising photocatalytic performances.