Microwave-Aided Green Synthesis of ZrO2/ZnO/AC Nanocomposite for Catalytic Degradation of Organic Dye

In this work, a simple green method was followed to prepare ZrO2/ZnO/AC nanocomposite with the aid of plant extract as a capping and stabilizing agent for the nanoparticles. The prepared nanocomposite was characterized with different techniques such as Fourier transform infrared (FTIR), ultraviolet–visible spectroscopy (UV-Vis), dynamic light scattering (DLS), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscope (SEM), thermal gravimetric analysis (TGA), and nitrogen adsorption for surface area. The successful formation of ZrO2/ZnO and loading it on the surface of activated carbon (AC) was confirmed by XRD, UV-Vis, EDS, and SEM images. Different degradation tests were performed under different conditions including the mass of the catalyst, pH, the concentration of dye solution and H2O2 used, and the catalyst. Blank tests ensured the necessity of both catalyst and H2O2 for the degradation to start. ZrO2/ZnO/AC was the best compared to ZrO2/ZnO, and AC with a degradation of 68% compared to 3% and 36%, respectively. The performance of ZrO2/ZnO was almost negligible confirming the importance of combining nanoparticles with suitable support. Furthermore, the highest degradation efficiency using ZrO2/ZnO/AC was achieved at a pH of 2 with degradation of 80% compared to 67% at a pH of 10, since the surface will be positively charged leading to a higher reaching rate of MO anions to the surface. Also, the highest performance was achieved when 0.8% of H2O2 was used with degradation of 91%. Despite the lower degradation in this work compared to what has been reported in the literature, it is still very promising since it was achieved under a stagnant and dark environment, which makes it a promising candidate for treating huge bodies of wastewater stored in dark places or containers.