The TiO₂ (B) nano-belts with excellent performance prepared via alkaline stirring hydrothermal method and its application to remove 17α-ethynylestradiol

In this work, TiO2 (B) nano-belts were synthesized by hydrothermal method under stirring, and static conditions and preparation conditions were optimized. The prepared materials were characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), photoluminescence spectroscopy (PL), and N2 adsorption/desorption measurement. The photocatalytic performance was evaluated by removing synthetic estrogen 17α-ethynylestradiol (EE2), which is the most potent endocrine-disrupting chemical. The results show that the TiO2 nano-belt possesses pure metastable monoclinic TiO2 (B) and has uniform nano-belt shape with 80~120-nm diameters and 62.904 m2 g-1 of specific surface area. Under the best optimal preparation conditions (0.5 g P25, 20 mL 10 mol L-1 NaOH, hydrothermal temperature 180 °C for 18 h under stirring, 400 °C calcination for 2 h), the TiO2 (B) has better catalytic activity with 100.00% removal rate towards 3 mg L-1 EE2 in 120 min. The removal rates of EE2 over catalyst which was prepared under static condition and P25 are 74.66% and 70.71%, respectively. The photocatalytic degradation rate constant of TiO2 (B) prepared under stirring condition (0.0379 min-1) is 4.51 times and 8.42 times than those of TiO2 prepared under static condition (0.0084 min-1) and P25 (0.0045 min-1). The excellent photocatalytic activity is mainly ascribed to longer one-dimensional nano-belt structure and effective suppression of photo-produced electron-hole.