Abstract
F–TiO2 was prepared by a simple precipitation method using titanium sulfate as the titanium source, hydrogen fluoride as the fluorine source and ammonia as the precipitant. CdS/F–TiO2 composites were prepared by hydrothermal synthesis of CdS and F–TiO2. The surface morphology, crystal phase composition, ultraviolet absorption band, fluorescence intensity, element composition, valence state, specific surface and pore structure of the samples were characterized by using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), ultraviolet visible absorption spectrum (UV-Vis-Abs), Molecular fluorescence spectrophotometer (PL) and X-Ray photoelectron spectroscopy (XPS) and Surface area analyzer (BET), respectively. The effects of the dosage of the photocatalyst, pH value, the concentration of methyl orange and the addition of H2O2 on the photocatalytic performance were investigated with methyl orange solution as the target degradation product. The results showed the optimum condition for photodegradation of methyl orange by 1% CdS/F–TiO2 is that the pH value, the solid-liquid ratio, the concentration of methyl orange and the dosage of H2O2 is 2, 2 g/L, 10 mg/L and 3%, respectively. Under the same conditions, the degradation rate of methyl orange by 1% CdS/F–TiO2 was 93.36% when 300 W metal halide lamp was irradiated for 20 minutes, which was significantly higher than that of F–TiO2. CdS has a significant effect on the morphology, crystallinity, grain size and the compound probability of electrons and holes after the F–TiO2 modification. The composite causes a significant red shift at the edge of the F–TiO2 light absorption band. The photocatalytic degradation of methyl orange by 1% CdS/F–TiO2 follows the Langmuir-Hinshelwood first-order kinetic model.
Highlights
At present, there are many kinds of photocatalysts, including semiconductor metal oxides and sulfides, such as TiO2, ZnO, CdS, ZnS, and so forth [1,2,3,4,5]
The surface morphology of the samples was characterized by field emission scanning electron microscopy (SIGMA 300, Carl Zeiss Co., Ltd., Jena, Germany); The crystal phase composition of the samples was investigated with X-ray diffraction (DX-2700, Dandong Haoyuan Instrument Co., Ltd., Liaoning, China) using Cu Kα radiation at a scanning rate of 0.05◦ s−1 and a working voltage/current of 40 kV/40 mA
When the concentration of H2O2 was 3%, It indicates that the addition of a certain amount of H2 O2 is beneficial to the degradation of methyl the reduction rate of methyl orange (20 mg/L) by 1% CdS/F–TiO2 reached 93.69% after 8 min
Summary
There are many kinds of photocatalysts, including semiconductor metal oxides and sulfides, such as TiO2 , ZnO, CdS, ZnS, and so forth [1,2,3,4,5]. Semiconductor composites is a good method of improving the photocatalytic activity of titanium dioxide. CdS to the conduction band of TiO2 , effectively inhibiting the recombination of photogenerated electrons and holes [10]. For the CdS/TiO2 composite formed by semiconductor composite, it combines the advantages of the two materials and has better stability and effectively improves the responsiveness to sunlight. It can be seen from the above that the photocatalytic performance of TiO2 can be effectively improved by fluorination modification or CdS compounding. The photocatalytic properties of the samples were studied using methyl orange as simulated sewage
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