Characterization and evaluation of ZnO/CuO catalyst in the degradation of methylene blue using solar radiation

Catalysts based on the combination of zinc oxide and copper oxide were synthesized at a 80:20 mass ratio by the Pechini method and calcined at 500, 600 and 700 degrees C for 1 h. These catalysts were characterized by XRD, SEM, FT-IR, BET, UV-Vis, TGA and XRF. They were subsequently tested for the removal of methylene blue dye by means of heterogeneous catalysis combined with solar radiation through a RCCD experimental design, analyzing the concentrations of H2O2 and methylene blue, as well as radiation exposure time and pH. The average crystallite size obtained was of 26.21, 28.21 and 35.91 nm for the respective calcined samples. The XRF was effective in determining the elements present in the catalyst, consisting of 75% zinc oxide and 25% copper oxide. The values of surface area were of 7.54, 7.19 and 3.92 m(2)/g, respectively. The experimental design showed that the catalyst calcined at 500 degrees C exhibited the highest removal efficiency (93%) of methylene blue with a dye concentration of 20 mg/L. Despite the need to carry out new studies to optimize the process, results suggest that the application of solar photocatalysis in the treatment of methylene blue with ZnO/CuO is a feasible alternative.