Preparation of Fluorine Modified Titanium Dioxide Catalyst and Its Photocatalytic Degradation for Oilfield Wastewater
The florine modification of titanium dioxide was realized by plasma discharge technique with C2H2F4 as F source,and the morphology and structure of the catalyst were characterized by XRD,XPS,UV-vis,PL,etc.The effectiveness of fluorine-modified titanium dioxide catalyst was studied in terms of the degradation of methylene blue and oilfield wastewater,and the corresponding influencing factors as well as the reusability of the catalyst were investigated.The results showed that for the corrosive medi-um of pH 6 with the addition of 8 g/L catalyst,the best degradation effect on oilfield wastewater was ac-quired with the COD removal rate up to 88％.For the corrosive medium with the presence of HCO3,CO3-,PO43-,and SiO32-,the photocatalytic induced reaction would be significantly inhibited,while Cl-had little effect on it.Besides,the hydroxyl radical(OH)was more critical for the photocatalytic related reac-tion.It follows that after plasma induced fluorine modification,a large number of ≡Ti-F bond and oxygen defects could be produced on the surface of titanium dioxide,achieving fluorine dopped TiO2 gaps(Ti-O-F-Ti bond),in turn,the ≡Ti-F and oxygen defects can promote the transfer of photogenerated electron-holes to the surface of titanium dioxide,meanwhile,the fluorine dopped TiO2 gaps caused a hybrid va-lence band of titanium dioxide,consequently narrowing the band gap width from 2.98 eV to 2.82 eV,which can enhance the absorption of the catalyst in the visible light region and improve the photocatalytic degradation efficiency of oilfield wastewater.
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