Response surface methodology (RSM) optimization approach for degradation of Direct Blue 71 dye using CuO–ZnO nanocomposite

The present study highlights the synthesis of CuO–ZnO nanocomposite via facile hydrothermal method at 150 °C and autogenous pressure. The structural and textural features of prepared composite material was characterized by several characterization techniques such as X-ray powder diffraction, Fourier transform infrared spectroscopy, Scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The optimized prepared nanocomposite was utilized for photocatalytic degradation of aromatic Direct Blue 71 dye (DB71) under natural sunlight conditions. The catalytic activity results by CuO–ZnO nanocomposite were observed to be higher than the reagent-grade zinc oxide under visible light conditions. The response surface methodology protocol (RSM) with central composite design was optimized by different photodegradation operational parameters such as pH, dye concentration, catalyst amount, and reaction time. The optimized RSM results demonstrated that a quadratic polynomial model was found suitable to define the relation between the photocatalytic activity and operational parameters. Moreover, the observed high R² value (0.9786) confirms a strong evaluation of experimental data. To achieve maximum DB71 degradation, optimized condition was found at 177.13 min of contact time, 3.93 solution pH, and 24.34 mg/L of dye concentration with 1.85 g/L of catalyst dose The identical optimum conditions resulted maximum 89.58% DB71 degradation.