Optimization of reactive black 5 degradation using hydrothermally synthesized NiO/TiO2 nanocomposite under natural sunlight irradiation

Abstract

In this study, the photocatalytic degradation of reactive black 5 using NiO/TiO2 nanocomposite as catalyst was optimized based on response surface methodology (RSM). NiO/TiO2 nanocomposite was fabricated through hydrothermal technique (P = autogenous, T = 150°C). The nanocomposite fabricated was characterized using powder X-ray diffraction, scanning electron microscopy, UV–vis spectrophotometer, and Fourier transmission infrared spectroscopy. The central composite design (CCD) was applied for the experimental design and process optimization. The optimization studies were carried out by changing initial pH, catalyst dosage, dye concentration, and contact time. The high regression coefficient (R2 = 0.9460, Radj = 0.9040) between the variables and the response indicated excellent estimation of experimental data by quadratic model. The optimum catalyst dose, pH, dye concentration, and contact time were found to be 2 g/l, 5, 40 mg/l, and 150 min, respectively, and under the optimal values of process parameters, the dye degradation performance of 86.1% was achieved. Based on the data of present study, it is concluded that CCD and RSM could be employed to model dye degradation parameters using NiO/TiO2 nanocomposite while optimizing and minimizing the number of experiments required.