Efficiently Synthetic TiO_2 Nano-sheets for PCE, TCE, and TCA Degradations in Aqueous Phase Under VUV Irradiation

摘要

The present study investigates the applicability of the synthesized titanium dioxide (TiO_2) for the removal of tetrachloroethene (PCE), trichloroethene (TCE), and 1,1,1-trichloroethane (TCA) in aqueous phase under VUV illumination. The photo-degradation results indicated that these harmful chemicals can be effectively removed under VUV irradiation, and the addition of the synthesized TiO_2 significantly enhanced their degradation. Moreover, using nitrobenzene (NB) as a probe of hydroxyl radical (·OH), the NB degradation rate was better over VUV/synthesized TiO_2, suggesting the high concentration of OH generated. The TiO_2 used has been synthesized by a simple hydrothermal solution containing tetrabutyl titanate and hydrofluoric acid and characterized by using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM), and X-ray photo-electron spectroscopy (XPS). The characterization results showed that the synthesized TiO_2 was in anatase form and consisted of well-defined sheet-shaped structures having a rectangular outline with a thickness of ～4 nm, side length of ～50 nm, and width of ～33 nm and has a surface of 90.3 m~2 g~(-1). XPS analysis revealed the formation of ≡ Ti-F surface bonds. Moreover, the synthesized TiO_2 nano-sheets have shown good stability after testing their photo-catalytic activity through five cycles of reuse in TCE degradation. In summary, it can be concluded from the results on both photo-catalytic activity and the surface analyses that the synthesized TiO_2 nano-sheets have a great potential for application in chlorinated solvent-contaminated groundwater remediation.