Functional Modification And Photocatalytic Properties Of Titanium Dioxide

TiO2,which has been regarded as a promising photocatalyst,is widely used in many aspects,such as environmental management.The photocatalytic efficiency of TiO2 is poor due to its narrow light absorption wavelength range and poorly effective utilization.Besides,TiO2 has no selection on photocatalysis,limiting its application scope.In respect to the defects,many attempts have been made to improve properties of TiO2.In this thesis,in order to improve photocatalytic efficiency,the surface of TiO2 was modified using poly(o-phenylendiamine)and graphene.And then,the molecular imprinting polymers with specific recognition ability based on the modified TiO2 were synthesized.The present thesis includes following three parts.1)In this research,the titanium dioxide coated with poly(o-phenylendiamine)and graphene was prepared successfully,respectively,and characterized by FT-IR,UV-Vis DRS and TEM.The results showed that the modified TiO2 with poly(o-phenylendiamine)possessed the core/shell structure,the thickness of the conductive polymer layer was about 3 nm and the light reflectivity of the photocatalyst reduced from 96 to 74%,improving significantly the light absorption of the Ti02 photocatalyst.In the case of the titanium dioxide coated with graphene,the ultraviolet absorption wavelength shifted from 401 to 405 nm.Consequently,the absorption scope of the TiO2 photocatalyst in the visible light region was broadened.2)Titanium dioxide coated with molecularly imprinted polymer(MIP-TiO2)was prepared using 4,4'-dihydroxydiphenyl ether(ODP)as template molecules and o-phenylenediamine as functional monomer.TEM observation showed that the MIP-TiO2 has much rougher surface than the NIP(non-imprinted polymer)-TiO2.Besides,The adsorption performances of MIP-TiO2 and NIP-TiO2 on the template molecules and structural analogues(4,4'-dibromodiphehyl ether and 4,4'-diaminodiphenylether)were compared.The results showed that the adsorption amount of MIP-TiO2 was as 5 times as that of NIP-TiO2.The adsorption amount of MIP-TiO2 on ODP was as 1.32 and 1.83 times as that.of MIP-TiO2 on 4,4'-dibromodiphenyl ether and 4,4'-diaminodiphenylether,respectively.3)The photocatalytic performances of the above TiO2 photocatalysts were explored.The activity of the photocatalyst TiO2 membrane modified by organosilicone was investigated form the photocatalytic degradation of nitrobenzene,and the photodegradation efficiency reached 37.91%within 2 h.For 4,4'-hydroxy diphenyl ether,the photodegradation efficiency of the poly(o-phenylendiamine)-modified TiO2 was 22.76%within 6 h,while the photodegradation efficiency of the TiO2 modified by graphene reached 40.8%in the same-time.The photodegradation efficiency of MIP-TiO2 reached 48.55%within 6 h,which had evident higher than that of NIP-TiO2.In addition,the photodegradating reaction mechanism of various modified TiO2 photocatalysts on 4,4'-hydroxy diphenyl ether was studied.