Surface Modified Nano-Titanium Dioxide For Highly Effective Photocatalytic Degradation Of Dye Wastewater

The rapid development of human society is often accompanied by the destruction of the ecological environment.One of the most pressing environmental problems is water pollution.Waste water caused by organic substances,especially dyes,is highly hazardous and difficult to be naturally degraded.Finding effective technical means to deal with these pollutants is an urgent task.Among all the treatment schemes,photocatalytic technology is one of the most promising ways to save energy,be green,and have no secondary pollution.However,current photocatalysts still have many deficiencies in terms of visible light utilization efficiency,catalytic activity,and service life.Based on these deficiencies,this study uses dipyridylbenzene as organic sensitizers and graphene oxide coupled with metal atoms as inorganic modifiers,respectively,to adjust the surface of Titania,and each gives an improved photocatalytic system with good properties in photo-generated charge separation and transport.First,m-dihydropyridine(HPB)was prepared through one-pot reaction of mxylaldehyde,ethyl acetoacetate,and ammonium acetate.After its dehydrogenation and aromatization,the organic ester sensitizer(EPB)with m-dihydropyridylbenzene skeleton was obtained,which was then hydrolyzed to give organic multi-carboxylic acid sensitizer(APB).Then,the surface modification of nano-titanium dioxide by organic sensitizers EPB and APB was achieved by hydrothermal reaction,and the surface structure characteristics and performance of the modified catalyst were studied.The results show that m-dipyridine benzene sensitizers can be firmly combined on the surface of titanium dioxide,which can enhance the separation of photogenerated charges,increase the adsorption of organic dyes and broaden the absorption spectrum of light,thus greatly improve the photocatalytic degradation ability of dye wastewater.In order to further improve the visible light response activity of nano-titanium dioxide,the ultrasonic stirring was first used to modify the surface structure of titanium dioxide with graphene oxide.Then,the in-situ photocatalytic reduction method was used to realize the loading of monoatomic layer silver on the surface of graphene oxide-modified nano titanium dioxide.The photocatalytic reaction experiments show that the photocatalyst after supporting silver atoms combines the advantages of titanium dioxide,graphene and metal atoms,which greatly improvesthe photocatalytic performance.After 20 minutes of visible light irradiation,the degradation rate of methyl orange wastewater can reach 99.6%.At the same time,research in the indoor environment shows that the modified photocatalyst has better photocatalytic activity under natural indoor light.The above research shows that the improvement of titanium dioxide needs to be considered from many aspects,such as broadening the absorption spectrum,improving the separation performance of photo-generated charges,and enhancing the adsorption capacity of organic dyes on the surface.The photocatalyst with higher catalytic performance can be obtained under the appropriate combination of multiple materials.