Preparation And Visible-light Photocatalytic Performance Of Cerium Doped Bismuth Oxide Photocatalyst

There are a lot of dyeing factories in our country. Dyeing factory produces muchwastewater, and dyeing wastewater contains complex components. It is a threat toecological environment and human health. Photocatalysis technology is one ofadvanced oxidation technology. Photocatalyst can be excited after light radiation andthen produce radicals with high oxidation. So photocatalysis technology can degradecomplex compounds like dyeing wastewater.The band gap of Bi2O3equals to2-3.96eV. That is to say some Bi2O3photocatalystcan respond to visible light. But pure Bi2O3is unstable. Rare earths have uniqueelectron shell structure. And it can separate the photo-generated electrons andphoto-generated holes effectively. Our country is rich in bismuth resource and rareearth resource. Cerium is a cheaper one in rare earth metal. Cerium doping canimprove the photocatalytic properties of bismuth oxide. And it is significant for theuse of bismuth and cerium resource and the control of environmental pollution toprepare Ce doped bismuth oxide photocatalyst which is respond to visible light.In summary, hydrothermal method or amorphous complexation was used to prepareCe doped bismuth oxide photocatalyst which was respond to visible light. Theprepared samples were characterized by X-ray diffraction (XRD), infraredspectroscopy (IR), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visiblediffuse reflectance spectroscopy (UV-Vis DRS) techniques. And Orange II was usedas the target pollutant. The effects of preparation conditions and reaction conditionson photocatalytic activity were investigated. The main achievements are as follows:1. Compared the samples prepared by hydrothermal method to the samplesprepared by amorphous complexation. The samples prepared by hydrothermal methodhad a better photocatalytic activity because of smaller band gap and higher level of adsorbed oxygen.2. The doping rate of Ce/Bi, pH value of solution in preparation process andcalcination time had effects on polymorphs and photocatalytic activity. The optimumpreparation conditions were: Ce/Bi rate was0.5, pH value of solution in preparationprocess was5and calcination time was2h. The photpcatalyst under optimumpreparation conditions was tetragonal Bi2O3. Its adsorption edge was about630nmand the bandgap was2.25eV. After two hours degradation under visible-light, thedegradation rate of Orange II was up to96.44%.3. When the dosage was in the range of1-5g/L, the reaction-rate-constantincreased with increasing dosage. When the initial concentration of Orange II was inthe range of40-100mg/L, the reaction-rate-constant decreased with increasing initialconcentration. k=13.3082×m1.7176×C0-1.2421(k represented reaction-rate-constant, mrepresented dosage, and C0represented the initial concentration of Orange II, theequation could be used when m=1-5g/L and C0=40-100mg/L). The degradation ofOrange II fitted in first-order kinetic equation. Photocatalyst rejected each other whenpH value of the solution was far from their isoelectric point. So the sample had abetter photocatalytic activity when the pH value of Orange II kept away from theisoelectric point of sample. Anions could restrain photocatalytic reaction. Theinhibition level was NO3-<Cl-<SO42-<HCO3-.