Preparation And Properties Of Molecular Imprinted TiO₂?SiO₂?Composite Materials

In this dissertation,some molecularly imprinted TiO2(SiO2)composites were synthesized by molecular imprinting technique in combination with sol-gel method,the adsorption and photocatalytic degradation performances of the prepared materials were tested,the results showed that the selectivity of the materials was obviously improved.The dissertation consists of the following four chapters.In chapter 1,the status quo and conventional treatment methods of the organic pollution in water were introduced.The basic properties,reaction mechanism,the preparation method of TiO2 catalyst,as well as the reaction mechanism and characteristics of molecularly imprinted sol-gel technology were summarized.Finally,the aims,significance and methods of the research were proposed.In chapter 2,a molecularly-imprinted amino-functionalized sorbent for selective remove of 2,4-dichlorophenoxyacetic acid(2,4-D)was prepared by a surface imprinting technique in combination with a sol-gel process.The 2,4-D-imprinted amino-functionalized silica sorbent was characterized by FT-IR,nitrogen adsorption and the static adsorption experiment.The selectivity of the sorbent was investigated by a batch competitive binding experiment using an aqueous 2.4-D and 2.4-dichlorophenol(2,4-DCP)mixture.The largest selectivity coefficient for 2,4-D in the presence of 2,4-DCP was found to be over 18,the largest relative selectivity coefficient between 2,4-D and 2,4-DCP over 9.The static uptake capacity and selectivity coefficient of the 2,4-D-imprinted functionalized sorbent are higher than those of the non-imprinted sorbent.The imprinted functionalized silica gel sorbent offered a fast kinetics for the extraction/stripping of 2,4-D,73%of binding capacity(200 mg L-1 2,4-D onto 20 mg of the imprinted sorbent)was obtained within 5 min and the adsorbed 2,4-D can be easily stripped by the mixture solution of ethanol and 6 mol L-1 HC1(V:V=1:1).In a test of five extraction/stripping cycles,the adsorption capacity of the sorbent was all above 93%of that of the fresh sorbent,which was shown to be promising for selective removal of 2,4-D from environmental samples and can be regenerated and used for many times on separation applications.In chapter 3,a novel 2,4-dichlorophenol imprinted TiO2-SiO2 catalyst was prepared by molecular imprinting technique in combination with sol-gel method.The prepared material was characterized by X-ray diffraction(XRD),infrared spectroscopy(IR),scanning electron-microscopy(SEM),transmission electron microscopy(TEM)and N2 adsorption measurement.The effect of the preparation condition on the degradation behavior,the photo-catalytic ability and selectivity of the prepared material were evaluated.The results showed that the imprinted material had good photo-degradation capacity and selectivity toward the target pollutant,which was shown to be promising for selective removal of 2,4-dichlorophenol from environmental samples.In chapter 4,a novel Cu2+ doped 2,4-dichlorophenol imprinted TiO2-SiO2 nanocomposite catalyst was prepared by molecular imprinting technique in combination with sol-gel methods.The prepared material was characterized by X-ray diffraction(XRD),infrared spectroscopy(IR),scanning electronmicroscopy(SEM)and N2 adsorption measurements.The photo-catalytic ability and selectivity of the material was also evaluated.The results showed that the Cu2+ doped imprinted material had not only good capacity but also favourable selectivity toward the photo-catalytic degradation of the target pollutant,which was shown to be promising for selective removal of 2,4-DCP from environmental samples.