Synthesis and Characterization of Fe2O3/NiO/C Nanocomposite for Photocatalytic Degradation of Methylene Blue

Abstract

Wastewater generated from textile industries mostly consists of the persistent synthetic organ ic dye, particularly methylene blue (MB), released to the environment before treatment has a significant trouble because of its adverse effects on human life and aquatic ecosystems. A va riety of treatment techniques have been broadly employed to remove pollutants from the envi ronment. Photocatalysis is one of the methods that possesses several advantages. In this study, the co-precipitation method was used to synthesize Fe2O3/NiO/C nanocomposites, with spent coffee grounds (SCGs) as the carbon source. Different molar ratio of precursor salts Fe(NO3)3.9H2O (0.2M, 0.1M, and 0.2 M) and Ni(NO3)2.6H2O (0.2M, 0.2M, 0.1M) were used, combined with 0.2 g carbon, corresponding to (1:1)C, (1:2)C and (2:1)C ratio, respectively. Then, the synthesized nanocomposites were characterized using XRD, FESEM-EDX, FTIR, UV-Vis DRS, and PL analytical techniques. From the XRD result, the average crystalline size was found to be 19.89, 13.22, and 15.86 nm for Fe2O3/NiO/C (1:1)C, (1:2)C, and (2:1)C com posites. The elemental composition and morphology were analyzed by FESEM-EDX analysis. The energy band gap was approximated to be 2.44, 2.47, and 2.43 eV for (1:1)C, (1:2)C, and (2:1)C nanocomposites. FTIR results showed the stretching of Fe-O and Ni-O bonds in α Fe2O3 and NiO in the synthesized (1:2)C nanocomposites. From the PL result, the (1:2)C composite showed the lowest PL intensity in comparison with (1:1)C, and (2:1)C indicated hindrance of electron-hole recombination (EHR). The degradation efficiency of synthesized nanocomposites was found to be 80.23%, 91.65%, and 87.22% for the (1:1)C, (1:2)C, and (2:1)C nanocomposites. Among these, (1:2)C sample showed the highest degradation efficien cy due to lower electron-hole recombination and was selected for photodegradation of MB. The improved photodegradation of MB was estimated to be 93.35% using a 30 mg/L initial MB concentration, pH 9, 10 mg catalyst dosage, 30 min contact time, and a visible light source.