Preparation of different crystal types TiO2 materials and its photodegradation performance in Congo Red wastewater

TiO2 gel was synthesized by the sol–gel method, and TiO2 photodegradation material (TiO2-PDM) was obtained after drying, grinding, and heat treatment, which was used for photodegradation of Congo Red wastewater. The Rietveld refinement method confirmed that the TiO2 material was anatase crystal when the calcination temperature was lower than 600°C. When the calcination temperature was between 600 and 750°C, the TiO2 material was anatase-rutile mixed crystal, and the proportion of rutile increased gradually. The content of the rutile crystal reached 98.3% at 800°C. Compared with TiO2-PDM at 800°C, TiO2-PDM at 500°C has a smaller crystal size and better dispersibility. The best photodegradation performance was identified as the 77.1% when the drying temperature was 80°C, the calcination temperature was 500°C, and the calcination time was 1.5 h.