Preparation And Photocatalytic Degradation Performance Of TiO₂/SiO₂/GDY Composite Photocatalyst

With the acceleration of China’s socialist modernization,issues such as eutrophication of water bodies and water pollution have become increasingly prominent,which will affect the sustainable development of China’s economy in the long run.Solving the problems of water eutrophication and water pollution,building a good ecological environment,and developing wastewater treatment technologies that are clean and sustainable and can recycle wastewater resources have become a common problem faced by current researchers.At present,the most widely used water treatment technology is biological treatment,physical treatment,and chemical treatment.Among these methods,the chemical treatment method has the characteristics of low cost,convenient and easy operation,and no secondary pollution in green,and becomes the most commonly used treatment method.The nano-semiconductor materials in the chemical treatment method maximize the sustainability,environmental protection and economic characteristics,and thus become the most commonly used processing materials in chemical treatment methods.Among the nano-semiconductor materials,titanium dioxide（Ti O₂）materials with good chemical stability,low cost and easy availability,and green pollution-free materials are the most suitable photocatalytic degradation materials.However,due to the large band gap of Ti O₂,the photoelectron-hole pair is easy to recombine and the surface area is small,and its application in wastewater dye treatment has been limited.Therefore,it is of great significance to study the nano-Ti O₂composites with good photocatalytic properties by studying the improved structure and properties of nano-Ti O₂materials.In this paper,titanium dioxide/silica（Ti/Si）composites were prepared by combining titanium dioxide with silicon dioxide（Si O₂）,and then titanium dioxide/silica（Ti/Si）composites were composited with graphene（GDY）.Titanium dioxide/silica/graphene（Ti/Si/GDY）composite photocatalytic materials with good photocatalytic properties,and their microstructure and photocatalytic properties were studied.Characterization and degradation test of industrial wastewater were carried out.The main experimental contents and results are as follows:（1）Preparation and photodegradation performance test of mesoporous Ti/Si composites.Nonionicsurfactant:polyethyleneoxide-polypropylene oxide-polyethylene oxide triblock copolymer（P123）are used as template,tetrabutyl titanate（TBOT）is used as titanium source,tetrasilicate tetra Ethyl ester（TEOS）is used as a silicon source,and green non-toxic surfactant 80（Span80）is used as a pore-expanding agent.By adjusting the ratio of the pore-expanding agent Span80 and the surfactant P123,as well as the ratio of TBOT and TEOS,A series of mesoporous titanium-silicon composites were synthesized by hydrothermal synthesis.The morphologies,structures and properties of the synthesized materialswere characterized by SEM,IR,BET and XRD,and the optimum preparation method of Ti/Si nanomaterials was determined.The photocatalytic properties of the prepared material and commercial titanium dioxide（P25）were tested under ultraviolet light for methylene blue（MB）dye solution.The degradation properties of the prepared material were compared with those of commercial titanium dioxide（P25）,and the stability of the material was tested by cyclic performance test.The results show that the Ti O₂modified by Si O₂has a larger specific surface area,and the dispersion of Ti O₂is better,and the removal rate of MB dye solution can reach 99.3%near-complete degradation under ultraviolet light.（2）Preparation of Ti/Si/GDY composite and test of visible light degradation performance.Ti/Si/GDY materials,titanium dioxide/silica/graphene（Ti/Si/GR）materials,and titanium dioxide/silica/carbon nanotube（Ti/Si/CNT）materials were synthesized by hydrothermal synthesis.The morphologies,structures and properties of the composites were characterized by SEM,XRD,UV-Vis DRS,XPS,Raman and other characterization methods to determine whether the Ti/Si/GDY materials were successfully compounded.The degradation performance of MB dye solution was tested under visible light,and the effect of composite materials on photocatalytic degradation of MB dye was studied.The results show that the light absorption range of the Ti/Si composite modified by GDY is expanded from the ultraviolet region to the visible light absorption region.The degradation rate of MB dye solution under visible light conditions reached 91.8%.（3）Ultrasound degradation of MB dye solution by Ti/Si/GDY composites.As for the problems of high concentration,dark color and poor light transmittance of industrial dyestuff wastewater,the degradation of MB dye wastewater by ultrasound was studied.The effects of initial dye concentration,adsorbent dosage,ultrasonic power and adsorption time on the degradation of MB dye solution by Ti/Si/GDY,Ti/Si/GR,Ti/Si/CNT,Ti/Si composites and P25 were studied.The optimal degradation conditions were determined by degradation experiments.The results show that Ti/Si/GDY composites can still degrade MB dye solution under the condition of ultrasonic catalysis.The maximum degradation rate of MB dye solution can reach 74.1%when the initial concentration of MB dye solution is 15 mg/L,the dosage of Ti/Si/GDY composites is 15 mg,the degradation time is 30 min and the ultrasonic power is 100 W.