Preparation of Eco-Friendly Nanocatalyst Calcium Oxide (CaO) for Oily Wastewater Treatment by Advanced Oxidation Process

In the present work, a novel eco-friendly nanocatalyst (NC) calcium oxide (CaO) is synthesized from the waste of tomato plants by physical method for the degradation of oil in oily wastewater by photocatalytic technology as a sophisticated oxidation process. The characterization of NC prepared is described by dynamic light scattering (DLS), Brunauer-Emmett-Teller (BET) analysis, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), X-ray powder diffraction (XRD), and energy-dispersive X-ray (EDX) spectroscopy, which illustrated that the NC prepared possessed a nanoscale size and a cubic crystal structure. The activity of NC in the photodegradation process is evaluated using oil concentration (100–500 ppm), amount of NC (0.1–1) g/L, and pH (4–12) at a specific aeration rate of 1 L/min and time irradiation of 30–180 min and under UV light. The findings showed that the degradation efficiency of oil increased with an increased amount of NC, time, and pH while decreasing with increased oil concentration. The maximum degradation of oil reached 83.0% at optimum conditions (oil concentration = 100 ppm, amount of NC = 0.6 g/L, pH = 7, time of irradiation = 120 min, and temperature = 23 ◦C). This work illustrates that the novel NC can be employed as an environmentally friendly and economical photocatalyst and might be improved in its characteristics and performance by thermal technique (calcination) to enhance the reduction of oil from oily wastewater.