Photocatalytic process for the tetracycline removal under visible light: Presenting a degradation model and optimization using response surface methodology (RSM)

[Display omitted] •TC was remarkably degraded using TiO2/Fe2O3 nano photocatalyst under visible light.•60 W lamps have been used as light, indicating considerable saving of energy.•A polynomial model of degradation and optimization was presented based on RSM. Nowadays tetracycline (TC) has a wide range of application in the world. Such a resistant anti biotic can penetrate into water resources and severely threat human and fauna health. Photocatalytic removal of TC was investigated under visible light using TiO2-Fe2O3 photocatalyst and maximum degradation efficiency was observed as 93.00%. Central composite design (CCD) was used to optimize kinetic of degradation based on response surface methodology (RSM). The correlation coefficient, F-value, and P-value of the fitted second order model were obtained 0.9863, 77.33, and smaller than 0.001, respectively; these figures account for the suitable adequacy of the model. Catalyst dosage, TC concentration, time, and light intensity were chosen as numerical variables to scrutinize their effects on the TC removal efficiency. Catalyst loading was determined as the most significant term in the fitted polynomial. Optimization of values for variables was also done and it included 79.75% of predicted degradation with 0.787 value of desirability.