Optimization of hydrothermal synthesis of Bismuth titanate nanoparticles and application for photocatalytic degradation of Tetracycline

In this research, hydrothermal process was used to synthesize Bi4Ti3O12 nanoparticles under supercritical water condition, and using Bi2O3 and TiO2 as precursors. The prepared nanoparticles were analyzed by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-vis diffuse reflectance spectroscopy. Hydrothermal synthesis of Bi4Ti3O12 was optimized successfully via response surface methodology (RSM), and through Box-Behnken design. Effect of selected process parameters including temperature, reaction time, and pH were investigated on the production yield of Bi4Ti3O12 nanoparticles. Analysis of variance (ANOVA) demonstrated that the suggested quadratic model can interpret the experimental data, properly (R2 = 0.9978 and R2- adjusted = 0.9929). Moreover, the optimum conditions for the production yield was found to be the temperature of 497 °C, pH value of 11.8, and reaction time of 1.9 h. The production yield obtained from the RSM under the optimum condition was attained about 63.9%. Produced bismuth titanate nanoparticles were applied for degradation of Tetracycline antibiotic through photocatalytic process under visible and UV light irradiation. UV-visible diffuse reflectance spectroscopy showed that bismuth titanate has a band gap of 2.6 eV, and Bi4Ti3O12 nanoparticles demonstrated a great photocatalytic activity for Tetracycline photo-degradation. Narrow band gap as the main advantage of bismuth titanate makes it an energy and cost effective photocatalyst which allows removing around 65% of tetracycline under visible light irradiation.