Influence of calcination temperature on TiO2 nanotubes’ catalysis for TiO2/UV/O3 in landfill leachate solution

Abstract

The influence of calcination temperature on TiO2 nanotubes’ catalysis for TiO2/UV/O3 was investigated. TiO2 nanotubes (TNTs) were prepared via the sol-gel method and calcined at 300–700 °C, which were labeled as TNTs-300, TNTs-400, TNTs-500, TNTs-600 and TNTs-700, respectively. TNTs were characterized by transmission electron microscopy(TEM) and X-ray diffraction (XRD). It is found that TNTs calcined at 400 °C showed the best thermal stability. When the calcination temperature increased from 400 °C to 700 °C, the special structure of tubes was destroyed and gradually converted into nanorods and/or particles. The transformation from anatase to rutile occurred at 600 °C, and the rutile phase was enhanced when the calcination temperature was increased to over 600 °C. The calcination temperature’s influence on TNTs’ adsorption activity for chemical oxygen demand (COD) and catalytic activity for TiO2/UV/O3 was investigated in landfill leachate solution. In landfill leachate solution, the adsorption activity of COD decreased in the reduced order of TNTs-300, TNTs-400, TNTs-500, TNTs-600 and TNTs-700. In photocatalytic ozonation, TNTs-400 showed the best catalytic activity while TNTs-700 exhibited the worst. In other three processes, the COD removal of TNTs-300/UV/O3 was higher than those of TNTs-500/UV/O3 and TNTs-600/UV/O3 in the first 20 min, and then became close to those of the latter two in the following 40 min. Compared with TNTs-300 and TNTs- 400, TNTs-600 had the best anti-fouling activity, while TNTs-500 and TNTs-700 had lower anti-fouling activity than the former three. In photocatalytic ozonation, the calcination temperature of 400 °C was appropriate when TNTs were obtained at the synthesis temperature of 105 °C.