Preparation And Application Of Solar Photocatalytic Materials With Multilevel Structure Based On ZnO/Eu₂O₃ Rods

Industrialization and urbanization will bring serious water pollution,including the widespread use of textile dyes in life especially antibiotics abuse and the proliferation of pathogenic microorganisms and so on.These serious damage to the ecological environment hinders the social and economic development.Dealing with water pollution by photocatalysis is a kind of eco-friendly and effective method.Metal oxide is a common photocatalysis,which is widely used in light catalytic disinfection and organic matter degradation.However,to realize the preparation of the material with highly light catalytic activity is still a huge challenge by optimizing the composition and structure.It is reported that utilizing MOFs derivative method can effectively control the component and structure of oxide-based photocatalysis material to improve the visible light catalytic properties.In this work,the linear MOFs with high specific surface area was employed as the sacrifice template by pyrolytic conversion.Besides,MOFs derivative metal oxide composite photocatalyst modified by the precious metal nanoparticles was obtained through a method of in situ reduction.Moreover,the photocatalytic degradation performance and the relationship between material structure and performance were studied.The details are summarized briefly as follows:First of all,Zn Cl₂and BTC were prepared to synthesize linear MOFs（Zn-BTC）at room temperature and a series of ZnO-C visible light catalytic materials were obtained by calcining Zn-BTC.Besides,the coordination reaction time and calcination temperature on the morphology structure of the visible light catalytic materials were studied respectively.The experimental results shows that caterpillar ZnO-C composite materials was obtained when the coordination reaction time control in 30 min and calcination temperature is 550℃.In order to further optimize the photocatalytic activity of this material Ag nanoparticles were loaded on this photocatalytic material to get caterpillar-shaped Ag-ZnO-C composites by the method of visible light reduction.The forming mechanism and morphology features of caterpillar-shaped visible photocatalysis ZnO-C-550 and Ag-ZnO-C-550 were analyzed systematically.The theoretical analysis suggests that a caterpillar-shaped part mainly comes from the precursor of micron-sized MOFs,flagella-shaped part mainly comes from the nanorod MOFs.Secondly,the photocatalytic degradation of pollutants,photocatalytic bactericidal performance and the photocatalytic mechanism of ZnO-C-550 and Ag-ZnO-C-550 composite materials were analyzed.In this work,MB、Pn P and AMX were used as the substrate template in visible light catalytic experiment,and the E.coli was employed as the substrate in antibacterial experiment.The adsorption performance and visible light degradation performance of ZnO,ZnO-C-550,Ag-ZnO-C-550 were analyzed in detail.In the test of photocatalytic degradation of pollutants,the reaction rate constants of ZnO nanorods、ZnO-C-550 and Ag-ZnO-C-550 were 34.5×10^-3min^-1、52.2×10^-3min^-1、148.4×10^-3min^-1respectively,and the degradation rate were 70.9%99.4%99.8%respectively by photocatalyzing 20mg/L MB.Besides,the reaction rate constants of ZnO nanorods、ZnO-C-550 and Ag-ZnO-C-550 were 2.7×10^-3min^-1、6×10^-3min^-1、6.8×10^-3min^-1respectively,and the degradation rate were 62.7%81.7%89.3%respectively by degrading 10mg/L PNP.And the reaction rate constants of ZnO nanorods、ZnO-C-550 and Ag-ZnO-C-550 were9.4×10-³min^-1、19.6×10^-3min^-1、13.8×10^-3min^-1respectively,and the degradation rate was56.3%,85.5%,90.1%,respectively by degrading 91.3mg/L AMX.The efficiency of Ag-ZnO-C-550 for MB could still reach 97.2%after fifth cycles.MOFs provides high ratio surface area and fast adsorption for pollutants,but also promotes the photoproduction electron transfer and reduces the carrier of the compound.In addition,the photocatalyzed efficiency of Ag-ZnO-C-550 nearly doubledthan before for degrading MB,and it also has a certain degree of increase for PNP and AMX.The degree of response of visible light was broadened by the loading of precious metal（Ag）,and the light antibacterial sterilization efficiency of a small amount of this product was reached more than 99.99%to inactivate E coli within 20 min.Finally,the linear organic skeleton of rare earth metal（Eu-mofs）was synthesized by using rare earth metal salts,and further self-assembled to form sea urchin-shaped multi-stage structure Eu₂O₃-C and Ag-Eu₂O₃-C composite photocatalyst were prepared by means of high-temperature calcination.The results showed that the material could retain the structure of sea urchin-shape and effectively degrade MB after calcination.Combining the photocatalysis with membrane material is advantageous to the separation of the catalyst.Quantitative Ag-Eu₂O₃-C was deposited on the surface,and further deposited titanium dioxide by the method of ALD,finally Eu₂O₃-C-Ti O₂composite was onbtained.The research shows that the coated sea urchin-shaped Eu₂O₃-C nanofiber membrane with 6.3wt%titanium dioxide by ALD had the best performance of catalyst,and the photocatalytic reaction rate constant was11.8×10^-3min^-1,degradation rate was reached to 93.8%,which provides simple and quick way for photocatalytic disinfection industrial,and it will be more competitive than titanium dioxide nanofiber membrane in water pollution part.