Research On Preparations,Characterizations And Photocatalytic Properties Of BiYTi₂O₇and BiYTi₂O₇-PAIN Composite Photocatalysts

Photocatalytic oxidation technology is a promising, effective and energy-saving water treatment technology without any secondary pollution.In this paper, novel visible-light responsive photocatalyst BiYTi2O7was prepared by solid-state reaction. The characterization of BiYTi2O7revealed that single-phase BiYTi2O7was synthesized successfully at1150℃for30h and crystallized with pyrochlore-type structure, stable cubic crystal system by space group Fd3m. During the crystallization process of BiYTi2O7, the Bi-O, Y-0octahedrals and Ti-O tetrahedrons were rearranged from disorder to order, and thus formed the lattice skeleton. Besides, only Bi, Y, Ti, O were detected in the BiYTi2O7and the average atomic ratio of Bi:Y:Ti:O was almost1:1:2:7. The band gap energy of BiYTi2O7was2.349eV. Moreover, the specific surface area of BiYTi2O7was1.8905m2g-1.The photocatalytic activities of BiYTi2O7were evaluated by the photocatalytic degradation of Indigo Carmine (IC) and Azocarmine G (AG). The effects of some experimental conditions (such as synthetic conditions of photocatalyst, photocatalyst dosage, initial concentration and pH of dyes) on photocatalytic reactions were studied. The effects of electron acceptors such as H2O2, NaCl and Na2SO4on photocatalytic reactions had also been carried out. The photocatalytic degradation of IC and AG with BiYTi2O7followed the first-order reaction kinetics, and the first-order rate constants were0.279h-1and0.056h-1, respectively. It illustrated that BiYTi2O7was more suitable for photocatalytic degradation of IC whose structure was much simpler and the molecular mass was much smaller. Finally, the circulating runs in the photocatalytic degradation of IC and AG with BiYTi2O7under visible light were checked in this experiment. It indicated that BiYTi2O7photocatalyst had high stability and would not photocorrode during the photocatalytic degradation.In addition, BiYTi2O7-PANI composite photocatalysts were synthesized via chemical oxidative polymerization method for the first time in order to solve the promblem of lower photocatalytic degradation rate of AG with BiYTi2O7. The XRD and ESM-EDS revealed that the addition of polyaniline would not change the lattice structure of BiYTi2O7and would not introduce other elements except carbon and nitrogen. UV-Vis concluded that visible light absorptions of these composite photocatalysts were increased because of addition of polyaniline. Subsequently, the photocatalytic efficiency of AG was improved.