Preparation And Photocatalytic Activity Of Ternary Nano-TiO₂ Composites

In recent years,with the vigorous development of economy and industry,the contradiction of environmental pollution has become increasingly prominent.Environmental-friendly photo-catalytic technology has become a research hot-spot to deal with environmental problems.Among them,semiconductor titanium dioxide with high efficiency,low cost and easy access,and no secondary pollution has shown great application prospects.In this paper,Anastasia TiO₂ was prepared by sol-gel method?Sol-gel?,and the defects were modified by TiO₂,such as low TiO₂ enrichment ability,high void junction electron pair recombination rate,wide band gap and hard recovery of powder catalyst.A two-dimensional GO/TiO₂ composite catalyst and three-dimensional Fe₃O₄/GO/TiO₂ composite catalyst were prepared by solvothermal method.Methylene blue solution was used.?MB?as the target,the optimum preparation conditions of the three catalysts were explored,and the physicochemical properties of the three catalysts were analyzed by TEM,XRD,UV-Vis and other characterization methods.The catalyst prepared under the optimum conditions was applied to the removal of Methylene blue.The effects of solution pH,catalyst dosage and initial concentration of pollutants on the removal rate of Methylene blue were investigated.The long-term operation stability and recycling performance of the catalyst were also studied.Further,the catalyst was applied to the advanced treatment of effluent from sewage treatment plant,and the applicability of the catalyst in the actual wastewater treatment was explored.The conclusions are as follows:?1?the optimum conditions for preparing TiO₂ by sol-gel method are as follows:n[C₁₆H₃₆O₄Ti]:n[C₂H₅OH]:n[H₂O]:n[CH₃COOH]:n[CTAB]=1:28:3:4:0.01;pH=2;hydr-olysis temperature is 20?;calcination temperature is 450?.When 0.5 g/L was added to the prepared catalyst,MB was completely degraded in 230 minutes.?2?The optimum mass ratios of binary GO/TiO₂ composite catalyst and ternary Fe₃O₄/GO/TiO₂ composite catalyst prepared by solvothermal method in one step are4:100 and 8:4:100.The two composite catalysts degraded MB completely in 90minutes and 70 minutes respectively,which greatly improved the photocatalytic performance of TiO₂.When the solution was alkaline,the photocatalytic performance of the materials was better.The ternary Fe₃O₄/GO/TiO₂ composite catalyst could degrade MB completely in 50 minutes.?3?Magnetic Fe₃O₄ can simply solve the problem of difficult recovery of TiO₂.powder.After three times reuse,the ternary catalyst with mass ratio of 8:4:100 can still recover 95%of the catalyst and 87.6%MB was degraded.Compared with pure TiO₂.,the recovery rate increases by 23.9%,which greatly improves the reusability of TiO₂.?4?The characterization of three materials,such as TEM,XRD and UV-Vis,further proves that the TiO₂ of the sol-gel method is anatase nano TiO₂,and the introduction of GO improves the photocatalytic performance of TiO₂,and has successfully solved the difficult problem that pure TiO₂ is difficult to use visible light.Fe₃O₄ not only adds magnetism to the catalytic material to solve the problem of difficult recovery of powders,but also enhances the response value of the material in the visible spectrum region,improves the photocatalytic performance of TiO₂.and broadens the scope of practical application.?5?The degradation of Methylene blue by TiO₂.,GO/TiO₂ and Fe₃O₄/GO/TiO₂accorded with the first-order kinetics model,R²>0.96,and the reaction rate constant K value of Fe₃O₄/GO/TiO₂ was the highest,which further proved that Fe₃O₄/GO/TiO₂had higher catalytic efficiency than GO/TiO₂ and TiO₂.?6?0.5 g/L ternary Fe₃O₄/GOTiO₂ composite catalyst can degrade 55.6%macromolecular organic matter in the effluent of secondary sedimentation tank of municipal sewage treatment plant in 360 minutes,greatly reducing aromaticity,and removing 34.9%COD,reaching 44.8 mg/L,meeting the first-class A standard of municipal sewage discharge,which has high practical application.