2025/07/28 by LEMA YADETA
paper · doi:10.20372/nadre:13116
Advisor: Asnake Lealem (PhD) ABSTRACT Methylene blue are extremely harmful to the environment and could be harmful to humans, animals, and plants. As a result, remediation to efficiently remove these toxins from industrial effluents is important work. In context of this, the use of mixed metal oxide nanocomposites for photo-degradation of organic pollutants has emerged as a major research focus. In this study single nanoparticles of (CuO, ZnO, and NiO), binary nanocomposites of (ZnO/CuO, ZnO/NiO, and NiO/CuO) and different molar ratio combination of ZnO/NiO/CuO ternary nanocomposites were synthesized by green synthesis method using Azadirachta indica (neem) leaf extract. The optical, crystallinity, and functional group of synthesized nanomaterials were characterized using ultraviolet visible spectrophotometer, X-ray diffractometer, and Fourier transform infrared spectrophotometer techniques, respectively. The optical band gaps were calculated from the UV vis spectra of CuO, ZnO, NiO, ZnO/CuO, ZnO/NiO, NiO/CuO and ZnO/NiO/CuO. From the X RD diffraction pattern the average crystalline size of green synthesized nanomaterials were in the range of 11.77- 25.26 nm. The Zn-O, Ni-O and Cu-O, stretching vibration bands were observed in FT-IR analysis. The photocatalytic activity of synthesized nanomaterials under sun-light irradiation for the degradation of methylene blue was evaluated. The effect of various parameters such as pH of dye solution, dye concentration, contact time and catalyst dose were investigated for the degradation of methylene blue. The results revealed that the optimum photocatalytic degradation conditions of methylene blue were as follows: pH =11, illumination time = 30 min, catalyst dosage = 60 mg and concentration of methylene blue = 10 mg/L. Under these optimized conditions, the removal efficiency of different photocatalysts against methylene blue were follow the order as: - NiO (72.6%) < ZnO (76.34%) < CuO (79.28%) < ZnO/CuO (82.40%) < NiO/CuO (85.10%) < ZnO/NiO (87.04%) < 1:1:2 (89.23%) < 1:1:1 (92.33%) <2:1:1 (95.42%) < 1:2:1 (99.54) in 30 min. This study showed the better photo-catalytic efficiency of ZnO/NiO/CuO (1:2:1) ternary oxide synthesized with neem leaf extract. Keywords: Nanomaterials, metal oxides, photocatalytic activity, methylene blue and degradation.