Enhanced photocatalytic degradation of an azo textile dye by using TiO2/NiO coupled nanoparticles: Optimization of synthesis and operational key factors

In this study, TiO2/NiO coupled nanoparticles were prepared by impregnation method. The effect of synthesis variables, such as NiO content and calcination temperature, were studied in the photocatalytic degradation of C.I. Basic Red 46 (BR46) as a model pollutant from textile industry. XRD, SEM, TEM, DRS, and EDX techniques were used for the characterization of the prepared nanoparticles. The coupling NiO as a p-type semiconductor with TiO2 as an n-type semiconductor could produce special electrons and hole transfers, which the n–p junction is able to facilitate the separation of the electron–hole pairs and thus improve photocatalytic activity of the TiO2 nanoparticles. TiO2/NiO coupled nanoparticles with NiO content of 30 wt% and calcination temperature of 650 °C indicate the highest photocatalytic activity. The effect of operational variables were predicted and optimized using response surface methodology (RSM). The results showed that the predicted data from RSM was found to be in good agreement with the experimental results with a correlation coefficient (R2) of 0.9667. The maximum degradation efficiency (91.05%) was achieved at the optimum operational conditions: initial BR46 concentration of 10.21 mg L−1, catalyst dosage of 0.46 g L−1, irradiation time of 30 min, and distance of the solution from UV lamp of 3 cm.