Influence Of Rear-earth Elements Doping On Nano-TiO₂ Photocatalysis Performance

In this thesis, Cyclic Voltammetry and ESR method were adopted to explore electrochemical behaviors of TiO₂ doped by rear-earth elements and variation regularity of radical signal. No new phases were found in XRD diagram after doping of rare-earth elements. The measure of Cyclic Voltammetry illustrated that the signal optimization subsequence is Nd>Sm>La>Ce>TiO₂, which basically follows the subsequence of oxidizability. Nd doping is better than other elements doping which is major because of strong basicity center on the surface of the Nd₂O₃, superficial layer dope energy lever and oxygen anion (O₂) which is an important intermediate created when TiO₂ produces the hydroxyl radical and is the important factor for making rear-earth doping own catalysis. The test of ESR indicated that in dark the subsequence of signal of the hydroxyl free radical after rear-earth doping is consistent with that of measure of Cyclic Voltammetry. The ESR showed that signals of the hydroxyi free radical in ultraviolet light and visible light are weaker than that in dark, which is because of the different surface between rear-earth doping and TiO₂ with no rear-earth doping and that the increasing of light intensity enhanced the consumption velocity of·OH, resulting in the signal of·OH in ESR weak.Adopting the clay as carrier, active carbon as aided sorption agent and rear-earth doped TiO₂ as resources of photo catalysis to degradate dye wastewater.The effect of the doping on photocatalysis were studied. It is found that the clay with low cost could solve the carrier problem and extremely enhance the TiO₂ photo catalysis behavior owing to active carbon and bivalent Mn. Ultraviolet visible diffused reflection measure showed that composite carrier widened TiO₂ response range towards light, establishing the favorable foundation for photo catalysis reaction. The test of ESR illustrated that active carbon involved the bivalent Mn extrication. And experiment approved that bivalent Mn can participate in the Fenton-typed reaction, promoting the formation of hydroxyl free radical and superoxide free radical which increased the photo catalysis of the composite carrier. The determination of absorbance in the degradated dye solution indicated that the composite carrier behaved very well during degradating the dye solution. Ultraviolet visible light absorption indicated that the effect of composite carrier on dye wastewater is not only absorption but also photo catalysis degradation.