Synthesis And Property Of Spherical Mesoporous SiO₂/TiO₂

With the rapid development of textile,printing and dyeing engineering and other related industries,a large number of dye wastewater has been produced,which brought serious pollution to the ecological environment.The dye wastewater is toxic,and the color is obvious.It is easy to dissolve and diffuse in the water to cause pollution to the water resources,thus affecting the ecological balance.Nanometer TiO₂ is a kind of stable,safe,cheap and non polluting green catalyst.TiO₂ photocatalysis is the oxidation and degradation of organic pollutants in the environment by photo irradiation to produce electronic-hole and then react with oxygen and water to form hydroxyl radicals.However,nano TiO₂ has a low utilization rate of sunlight and the process is not easy to recycle.Therefore,the research and development of catalyst with high efficiency and practical application performance is of great significance.In this paper,SiO₂/TiO₂ composites were successfully prepared by sol-gel combined hydrothermal method,and the properties of the materials were studied.Specific research contents and conclusions are as follows:（1）SiO₂/TiO₂ composite was prepared by sol-gel combined hydrothermal method with Si/Ti（molar ratio）as 0,0.05,0.1,0.3,0.5.Using scanning electron microscope（SEM）,X ray diffraction（XRD）,Fourier transform infrared（FT-IR）,surface area analysis and other methods on the morphology and crystal of the composite were characterized.Based on the photocatalytic degradation of methylene blue（MB）experiment examined its photocatalytic performance.The results showed that SiO₂/TiO₂ was a spherical mesoporous composite material.With the increase of Si content,the specific surface area increased gradually,and the maximum was 343.54.However,the crystallization of TiO₂ was inhibited with the increase of Si content.Therefore,a certain proportion（1:0.1）of Si doping can improve the photocatalytic performance of TiO₂.（2）With Ti/PEG（mass ratio）is 0.25,0.22,0.19,0.16,0.13,and the template of the material was optimized by the method of sol-gel method and hydrothermal method.Through the SEM characterization of the material,as well as the photocatalytic degradation of MB performance testing experiments,it is proved that the role of PEG template.Finally,the amount of PEG added was 0.64g and its molecular weight was 10000.In the same way,the necessity of adding urea was proved,and the optimum adding amount of urea was 0.6g.（3）The control calcination temperature was 400℃,500℃,600℃,700℃,and 800℃,respectively.The SiO₂/TiO₂ composite was prepared by sol-gel method combined with hydrothermal method and the effect of calcination temperature on the performance of the catalyst was studied.The morphologies of the composites were characterized by SEM,XRD,FT-IR,specific surface area analysis and other test methods.By photocatalytic degradation of MB under 300W xenon lamp,get the best catalyst in the 400℃calcination.It was proved that the repeated use of the catalyst is very good,and the degradation rate of the repeated five times is more than 80%.The preparation of bulk catalyst to solve the problem for recycling of the catalyst,and the amount of catalyst and the dye solution pH were studied.When the amount of catalyst was 0.5 mg/mL,the pH was larger,which was beneficial to the catalytic degradation.（4）Application performance research:The best adsorption pH was 6,the reaction temperature was 35℃,the adsorption time was 20min,the amount of catalyst was 25mg,and the final adsorption amount was 8 mg/g,by the adsorption experiment of Pb²⁺.Verify the sunlight of MB degradation performance,and the actual dyeing wastewater was treated under 300W xenon lamp,which means the actual application performance of SiO₂/TiO₂catalyst.