E. coli inactivation by visible light irradiation using a Fe–Cd/TiO2 photocatalyst: Statistical analysis and optimization of operating parameters

In this study, the antibacterial effect of a Fe and Cd co-doped TiO2 (Fe–Cd/TiO2) visible light sensitive photocatalyst was optimized by varying operating parameters and using a response surface methodology to evaluate the experimental data. Twenty sets of disinfection experiments were conducted by adjusting three operating parameters, i.e. initial pH of the solution, reaction temperature and catalyst loading, at five levels. Based on the experimental data, a semi-empirical model was established and subsequently applied to predict the final concentration of Escherichia coli after 45 min exposure to the catalyst and visible light irradiation. Using the accurate model (coefficient of determination R2 = 0.963), optimum values were found to be 40.1 °C, 6.3, and 1.0 g/L for reaction temperature, initial pH of solution and photocatalyst loading, respectively. Under the optimized conditions, the Fe–Cd/TiO2 catalyst achieved a bacterial inactivation efficiency of 99.9% after 45 min of visible light illumination.