The Composite Of Bi₂WO₆ And Iron-based Materials And Its Photo-fenton Degradation Of Tetracycline Hydrochloride Wastewater

In the fifty years since the discovery of penicillin,the number of multidrug-resistant and extensively drug-resistant strains has increased,but the development of new antibiotics to tackle resistant bacteria has been woefully inadequate,leading to an increasing number of fatal infections.The elimination of antibiotic residues in the environment is a practical way to reduce the’genetic contamination’caused by the misuse of antibiotics.Photocatalysis,an advanced oxidation technology with mild reaction conditions and simple operation,is increasingly being used in the treatment of antibiotic wastewater.In order to cope with the disadvantages of slow reaction speed,low redox capacity and high electron-hole pair complexation rate,photocatalysis is coupled with Fenton technology,thus building an efficient reaction system with photocatalysis-Fenton catalysis working together.Bismuth tungstate（Bi₂WO₆,BWO）,a typical bismuth-based semiconductor material,is a member of the Aurivillius phase of chalcogenide,which has a relatively narrow band width and can directly absorb visible light.In order to improve the catalytic performance of BWO,this paper investigates the morphology control of BWO,conducts morphology screening for its subsequent compounding with iron-based materials,and prepares the composites FeOOH/BWO and BWO/MIL-100（Fe）as photo-Fenton catalysts by impregnation and mechanical stirring methods,respectively.Tetracycline hydrochloride（TCH）was used as the target pollutant for degradation under simulated sunlight to enable assessment of the catalytic performance of the materials.Based on the relevant results such as radical capture experiments and cycling experiments,the catalytic mechanism is analysed and discussed to provide data support and theoretical basis for the future development of efficient and stable BWO semiconductor catalysts.The main research elements of this thesis are as follows:（1）Spherical-like BWO（P-BWO）,sheet-like BWO（S-BWO）and rod-like BWO（R-BWO）were successfully prepared by using different kinds of organic solvents to control the growth process of BWO in a high temperature and high pressure hydrothermal process.The results of photocatalytic experiments showed that S-BWO had the best catalytic performance,with more than 50%degradation of TCH within 120 min,and its catalytic activity was also stable at the later stage of the reaction.In the results of the radical trapping experiments,the contribution of the active species in the three morphologies of BWO was in the same order of magnitude,indicating that the change of morphology affects the catalytic effect but not the catalytic mechanism when BWO is used as a photocatalyst.（2）Amorphous FeOOH quantum dots were successfully prepared by mechanical stirring at room temperature and pressure,and FeOOH quantum dots were successfully grown in situ on the S-BWO surface by impregnation.The performance of 3%FeOOH/Bi₂WO₆ is much better than that of single photocatalytic systems and pure phase materials,with a first-order kinetic constant of 0.0627 min^-1 in 20 min,and it has good stability and reusability.Meanwhile,comparative experimental results show that a suitable Fe:H₂O₂ ratio is beneficial for the activation and decomposition of H₂O₂ into·OH and·O^2-,in which the Fe:H₂O₂ coefficient is yet to be determined by further in-depth studies.（3）The metal-organic framework MIL-100（Fe）was successfully prepared by mechanical stirring method at room temperature and pressure,and S-BWO was successfully compounded with MIL-100（Fe）as the precursor,and the complex BWO/MIL with different weight ratios was prepared and tested for its photo-Fenton performance.Also,a set of comparison samples with S-BWO pre-positioned in the precursor were produced to explore the crystallisation of the composite.One of the 10%BWO/MIL showed excellent photo-Fenton performance with over90%degradation of TCH in 60 min and a first order kinetic reaction constant of 0.0716 min^-1in 20 min.