Chinese Journal of Applied Chemistry ›› 2016, Vol. 33 ›› Issue (3): 320-329.DOI: 10.11944/j.issn.1000-0518.2016.03.150258

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Preparation of the Keggin Type Chromium Substituted Phosphotungstates/Titanium Dioxide Nano Film and Its Visible Photocatalytic Performance

ZOU Xiaomei,CHEN Yan,ZHU Xingwang,LIU Gaopeng,GUO Xinwei,LEI Qin,KE Xiaoxue,LI Shuaixing,HUA Yingjie(),WANG Chongtai()   

  1. School of Chemistry and Chemical Engineering,Hainan Normal University,Haikou 571158,China
  • Received:2015-07-21 Accepted:2015-11-18 Online:2016-03-02 Published:2016-03-02
  • Contact: HUA Yingjie,WANG Chongtai
  • Supported by:
    Supported by the National Natural Science Foundation of China(No.21161007), the Key International Science and Technology Foundation of Hainan Province(No.2012-GH004, No.KJHZ2014-08), the Research and Development of Applied Technology of Hainan Province(No.ZDXM20130088, No.ZDXM2014099), the National Undergraduate Innovation Project(No.201411658027), the Undergraduate Innovation Project of Hainan Province(No.20140055)

Abstract:

A PW11Cr/TiO2 nano film photocatalyst was prepared on the surface of a glass slide via the sol-gel dipping pulling method using tetrabutyl titanate Ti(OC4H9)4 as the precursor of TiO2 and the Keggin type chromium substituted heteropolyanion(PW11Cr) as the visible light active component. Then the light absorption properties, chemical composition, crystal phase and surface morphology of the as-prepared catalyst were characterized using solid ultraviolet-visible diffuse reflection spectroscopy, infrared spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The interaction between PW11Cr and TiO2 in the film was discussed. Visible photocatalytic activity of the catalyst was assessed using photocatalytic degradation of RhB as a probe. Meanwhile, a photocatalysis mechanism was suggested and compared with that of TiO2. Influences of the calcination temperature, the PW11Cr dosage and the solution pH on the catalyst activity were also examined. In the end, a recycle test of the catalyst for RhB degradation was employed to evaluate the stability of the catalyst. The PW11Cr/TiO2 photocatalyst has a good absorption of visible light. The film obtained at low calcination temperature(100 ℃) is amorphous but crystal at high calcination temperature(500 ℃). The former has higher photocatalytic activity, and is employed to degrade RhB with a concentration of 10 μmol/L under the irradiation of 200 W metal halide lamp. The degradation ratio is 95% at 120 min and the COD removal is 72% at 4 h. The hydroxyl radicals are the main reactive oxygen species leading to RhB degradation. Low processing temperature, high PW11Cr dosage and high solution acidity are favorable to enhance the photocatalytic activity of the PW11Cr/TiO2 film. After recycles of 10 times for RhB degradaion, the photocatalytic activity of the PW11Cr/TiO2 film lose insignificantly.

Key words: Keggin-type Cr-substituted phosphotungstates, titanium dioxide, visible photocatalyst, sol-gel method, rhodamine B