Study On Preparation Of Molecular Imprinted And Metal Doped TiO₂Photocatalyst And Its Selective Degradation Of BPA In Water

The bad effects of Endocrine Disrupting Chemicals (EDCs) to human health and environment are concerned by the whole society. How to remove EDCs, which is in low concentration and with high toxicity, from environment especially from water has become a hotpot and difficulty in environmental management.The TiO2semiconductor materials, which have high chemical stability, low toxic and low price, were used widely for degrading organic pulluion. However, TiO2photocatalysis has no selectivity for degrading organics. How to improve the selectivity of TiO2photocatalyst has been a hot topic in the research of photocatalysis field recently. In this thesis, our work included2parts:1. Preparation of mesoporous TiO2through Sol-Gel methodThe molecular imprinting can effectively improve the selectivity of TiO2photocatalyst. Mesoporous imprinted TiO2were prepared through sol-gel method by combining mesoporous and the molecular imprinting at the first time.The nanoparticles materials were characterized by powder X-ray diffraction, transmission electron microscope, and nitrogen adsorption/desorption. It was proved there are mesopore structures in the materials. When the molar ratio of TiCl4/Ti(OBu)4was1.5:1, the quatily of P123was1g and the ageing time was32hours, the mesoporous imprinted TiO2material had the biggest surface area of148m2/g, which was3times of that of P25.The pH value of solution and the initial concentration of TiO2affected the photocatalyst activity. When the pH value was9.5and the initial concentration of TiO2was0.2g/L, the photocatalysts has the highest photocatalyst activity.When phenol was used as co-pollution, the selectively photocatalysis of the prepared imprinted TiO2was run. When molecular imprinted TiO2was applied as photocatalyst, the BPA was completely degraded after illumination of20min, and the phenol was degraded56.5%after illumination of2hours. When P25was used for photocatalysis, BPA was completely degraded after illumination30min, and the phenol was degraded90.2%after illumination in2hours. Comparing to P25, the imprinted TiO2materials have a higher degradation efficiency for BPA and a lower degradation efficiency for phenol. Therefere, the prepared imprinted TiO2realized a good selectively photocatalysis on BPA.2. Preparation of molecular imprinted/Zn doped TiO2microspheresUsing dodeeylamine (DDA) as the template, pure TiO2, imprinted TiO2, Zn doped TiO2and imprinted/Zn doped TiO2microspheres were prepared by hydrothermal synthesis method. In order to improve the photocatalitic activity and the selectivity of the photocatalyst, molecular imprinting and metal ions doping was combined creatively to prepare the TiO2materials. Therefore, the prepared materials have high selectivity for photocatalysis of the goal pollution. Meanwhile, the metal doping had extended the visable light absorption range of the photocatalyst and the use ratio of the light had been improved.In the proeess of sample preparation, the molar ratio of DDA/Ti(OBu)4, the stir time and the rection temperature would affect the aggregation of the TiO2particles. When the molar ratio of DDA/Ti(OBu)4was1:1, the stir time was3hours and the rection tempare was120℃, the TiO2microspheres have better decentrality. Meanwhile, the photocatalyst activivity could be improved by increasing of composition of doping Zn. However, the photocatalyst activivity could not be improved further when the percentage of doped Zn was above1.5%.When phenol was present as co-pullution, the selectively photocatalysis of the prepared4kinds of TiO2microspheres was test. When molecular imprinted/Zn doped TiO2was used as photocatalyst, the BPA was completely degraded after illumination of10min, which was faster than that for molecular imprinting TiO2(15min), Zn doped TiO2(15min) and pure TiO2(25min). Meanwhile, the phenol was degraded71%after illumination in2hours, which was lower then molecular imprinting TiO2(79.5%), Zn doped TiO2(74.3%) and pure TiO2(78.5%). The results demonstrated that, molecular imprinted/Zn doped TiO2has both higher photocatalytic activity and higher selectivity for photocatalysis of goal pollution BPA than pure TiO2, imprinted TiO2and Zn doped TiO2.