Preparation, Characterization And Photocatalytic Property Of Modified TiO₂/Rectorite Composites

Due to its high toxicity, degradation resistant, environmental persistence and harmful forbiology, chlorophenols will lead to serious environmental pollution problems when emittinginto the environment, especially of emissions of industrial wastewater containingchlorophenols which have caused serious pollution to water bodies in recent years. Thus,studying an effective technology or method for the degradation of organic pollutants likechlorophenols has become a focus of current research in the field of environment. Thesemiconductor TiO2photocatalytic technology is just the effective method because of itschemical stability, strong oxidation ability and no secondary pollution, which is widely usedin the degradation of organic pollutants in wastewater. However, TiO2still has someshortcomings in the aspect of photocatalytic application, such as easy recombination by thephoto-generated electron and hole, in response to a narrow range of light, easy to reunite andinactivation, difficult to separate and recycle and so on.In order to solve the shortcomings of TiO2, this paper prepared two kinds of modifiedTiO2/rectorite composite photocatalysts by sol-gel method, including Cu-doped TiO2/rectoritecomposite photocatalyst and N, Cu co-doped TiO2/rectorite composite photocatalyst. Theas-prepared composite photocatalysts were characterized by X-ray diffraction (XRD),Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, N2adsorption-desorption, X-ray photoelectron spectroscopy (XPS), UV-visible diffusereflectance spectra (UV-vis DRS). Meanwhile4-chlorophenol (4-CP) was chosen as the targetpollutant to investigate the photocatalytic properties of the two prepared compositephotocatalysts under ultraviolet light and visible light and a variety of different factors whichaffect theirs photocatalytic properties were also studied. The possible mechanism forphotocatalytic degradation of4-CP was discussed as well. The main conclusions are asfollows:(1) The Cu-doped TiO2/rectorite composite photocatalyst (TR-r-T) with photocatalyticactivity was prepared successfully by sol-gel method. TiO2in the prepared composite exists inanatase mainly, and the Eg values of all the prepared composites were decreased than that ofpure TiO2.(2) When Cu doping amount was0.5%and calcination temperature was500℃, theprepared composite photocatalyst (TR-0.5%-500℃) showed the best photocatalytic propertyfor degradation of4-CP with about70%degradation rate after180min under UV lightirradiation on the below reaction conditions: catalyst dosage of1.0g/L, initial concentration of20mg/L, the solution pH of5.(3) The N, Cu co-doped TiO2/rectorite composite photocatalyst (TR-rN) withphotocatalytic activity was prepared successfully by sol-gel method. TiO2was formedsuccessfully in the prepared composite with the kind of main anatase status, and successfullyloaded on the surface of rectorite.(4) All the prepared composites (TR-rN) had responses to visible light. And when Ndoping amount was1.0%, the prepared composite photocatalyst (TR-1.0%N) showed the bestphotocatalytic property for degradation of4-CP after180min under visible light irradiationon the below reaction conditions: catalyst dosage of1.0g/L, initial concentration of20mg/L,the solution pH of5. After recycling and reused for five times, the photocatalytic degradationrate of4-CP by the TR-1.0%N composite decreased slightly, which indicated that the preparedcomposite was reusable and high stability.