Study On Preparation And Catalytic Degradation Of ZIF-8@TiO₂ Composite Photo Catalyst

With the transformation and upgrading of China’s industrial production,high quality green development is the main development mode of China’s economy at present.A large number of organic pollutants have become a major problem of ecological environmental pollution in the process of green and innovative development.MOFs are a kind of nano porous materials with three dimensional periodic network structure which are composed of metal ions or metal oxide clusters and organic ligands.Adsorption photo catalysis technology was adopted to degrade organic pollutants.ZIF-8 with good thermal stability in MOFs was selected as adsorption material and TiO₂was selected as photo catalytic material in this thesis.TiO₂ was doped with elements I and Gd which calcined at 350 ^oC and 400 ^oC and recombined with ZIF-8.ZIF-8doped with Eu element was combined with TiO₂calcined at 700^oC in this thesis.The composites were characterized and the degradation ability of organic pollutants under ultraviolet light was investigated.The main work of this thesis is as follows:1.TiO₂ doped with different amount of potassium iodide（KI）was prepared by sol-gel method and ZIF-8@TiO₂（KI）was obtained by solvothermal synthesis method.It was characterized by XRD,SEM,BET,XPS and UV-Vis.The crystal form of TiO₂,the surface morphology,specific surface area,the change of element valence state and the change of band gap of the composite material were analyzed.The influence of different mole ratio of KI doping on the efficiency of TiO₂photo catalytic Congo red was explored.The results showed that TiO₂（5%KI）had the highest catalytic efficiency and the degradation efficiency of Congo red dye was 95.21%under UV light.The composite of TiO₂（5%KI）and ZIF-8 greatly improved the degradation efficiency.The catalytic efficiency was 76.42%after four cycles.2.ZIF-8（Eu）@Mc-TiO₂ was prepared by the composite of mixed TiO₂（Mc-TiO₂）and ZIF-8 doped with different amount of element europium（Eu）.The crystal form,surface morphology,specific surface area,element valence state and band gap of the composite were analyzed.The effects of different mole ratios of Eu on the photo catalytic basic fuchsin of ZIF-8（Eu）@Mc-TiO₂were investigated.The results show that ZIF-8（5%Eu）@Mc-TiO₂has the highest catalytic efficiency and the degradation efficiency of basic fuchsin is 99%after 1 h under ultraviolet light.The catalytic efficiency was 90.84%after four cycles.3.TiO₂ doped with different amount of element gadolinium（Gd）was prepared by sol-gel method which was combined with ZIF-8.The changes of crystal form,surface morphology,specific surface area,element valence state and band gap width of the material were analyzed.The effects of doping Gd with different molar ratios on the photo catalytic neutral red of TiO₂were investigated and the catalytic effect of composite materials.The results showed that TiO₂（0.3%Gd）had the highest catalytic efficiency and the degradation efficiency of neutral red was94.53%after 1 h of reaction under UV light.TiO₂（0.3%Gd）combined with ZIF-8 improved the photo catalytic efficiency which was 69.14% after being recycled for four times.