The comparative study of two kinds of β-Bi2O3/TiO2 binary composite and their removal of 17ɑ-ethynylestradiol
2020
Shi, Miao | Luo, Lijun | Dai, Jianhui | Xia, Lihong | Long, Junhong | Yang, Wenrong | Wang, Hongbin | Shu, Li
In this work, we used TiO₂ nanobelts and P25 particles as titanium sources to combine with β-Bi₂O₃ to form β-Bi₂O₃/TiO₂ and β-Bi₂O₃/P25 composites. The prepared samples were characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), and UV-vis absorbance spectroscopy and fluorescence spectroscopy. The structure and performance of two composites were comparatively investigated, and the β-Bi₂O₃ molar ratios in them were optimized and their roles in them were studied. The results showed that the TiO₂ nanobelts and commercial TiO₂ (P25) particles combined with β-Bi₂O₃ nanosheets. The optimal molar ratios of Bi to Ti element in two kinds of composites are 1:1. The β-Bi₂O₃ in P25/β-Bi₂O₃ makes more contribution to the improvement of photocatalytic activity of them than that in β-Bi₂O₃/TiO₂ because P25 particles are distributed on β-Bi₂O₃ nanosheet more uniformly. The photocatalytic activities of β-Bi₂O₃/TiO₂ (0.02275 min⁻¹) and β-Bi₂O₃/P25 (0.02382 min⁻¹) are 3.72 times and 3.90 times than that of pure β-Bi₂O₃ (0.0061 min⁻¹) for EE2 removal. The enhanced photocatalytic activities of two kinds of composites are ascribed to photo-induced interfacial charge transfer on the heterojunction between β-Bi₂O₃ and TiO₂ or P25. From the economic view, β-Bi₂O₃/P25 composites are better than β-Bi₂O₃/TiO₂ because TiO₂ nanobelts in the β-Bi₂O₃/TiO₂ composite are obtained from P25 via extra hydrothermal treatment in strong alkaline environment. The free radical capture experiment indicated that the dominant reactive species are h⁺ and •O⁻₂ for EE2 removal by TiO₂/β-Bi₂O₃ and P25/β-Bi₂O₃ composites.
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