The Fabrication Of Clay Modified Bismuth Tungstate Photocatalysts And The Photocatalytic Properties For The Degradation Of Organic Contaminants

The rapid development of China's economy and the significant improvement of people's living standards inevitably cause serious pollutions to the surrounding environment,such as domestic sewage,industrial wastewater,soil erosion and energy depletion issues.Therefore,searching for clean and pollution-free new water treatment technology is a major topic of discussion in the current scientific community.In recent years,semiconductor photocatalytic technology has received wide attention from the industry insider due to its advantages of environmental protection,sustainable utilization and low cost.As a traditional photocatalyst,titanium dioxide?Ti O2?has the characteristics of strong photocatalytic capability,non-toxicity and low price.However,due to these defects such as the large band gap?3.2 e V?,it can only be excited by ultraviolet light??<400 nm?,small specific surface area and difficulty inrecycling,which are extremely limited in the application.Bismuth tungstate?Bi₂WO₆?is favored by researchers as the best visible light catalyst in lanthanide oxide,but its poor adsorption and low quantum yield also restrict its process of development.Therefore,loading and modifying pure Bi₂WO₆ has far-reaching significance.In this thesis,a new photocatalytic material with large specific surface area and high visible light photocatalytic activity was prepared by combining Bi₂WO₆ with attapulgite?ATP?and iron-based montmorillonite?Fe/Na-MMT?,Which were tested for photocatalytic performance and characterized for crystal structure and morphology.The main experimental contents are as follows:In the first part,Bismuth tungstate/attapulgite?Bi₂WO₆/ATP?composites were prepared by solvothermal method,and their photocatalytic performance was evaluated by degrading dyeing wastewater Rhodamine B?Rh B?and antibiotic wastewater tetracycline?TC?.In addition,these analysis and identification were carried out by means of X-ray diffraction?XRD?,scanning electron microscopy?SEM?,Fourier transform infrared spectroscopy?FT-IR?,X-ray photoelectron spectroscopy?XPS?,specific surface area and pore structure distribution?BET?,UV-visible diffuse reflectance spectroscopy?UV-vis DRS?and liquid chromatography-mass spectrometry?LC-MS?.To explore the degradation mechanism of composite material to Rh B solution in free radical trapping experiments.The degradation mechanism of rhodamine B was explored in free radical trapping experiments.The experiments showed thatthe optimal degradation performance was obtained when the p H of the precursor solution was 1,the hydrothermal time was 18 h,the hydrothermal temperature was 180 °C,and the mass ratio of ATP to Bi₂WO₆ was 6%.Photogenerated holes?h+?and hydroxyl radicals?·OH?play a major role in the photodegradation process.The results show that the incorporation of ATP can not only improve the adsorption performance of organic pollutants,but also enhance the responsiveness of visible light,thereby inhibiting the photogenerated electron-hole recombination and improving the separation efficiency of photogenerated carriers.In the second part,Bismuth tungstate/Iron Oxide/Sodium montmorillonite?Bi₂WO₆/Fe3O4/Na-MMT?composites were prepared by the high-temperature calcination method and the solvothermal method,and their photocatalytic performance was evaluated by degrading Rh B.Besides,these analysis and detection were carried out by means of XRD,SEM,XPS,BET,FT-IR,UV-vis DRS and vibrating sample magnetometer?VSM?.To explore the degradation mechanism of composite to Rh B solution in free radical trapping experiments.The experiments showed that the better degradation performance was gained when the hydrothermal temperature was 160 °C,the hydrothermal time was 22 h,and the mass ratio of Bi₂WO₆ to Fe/Na-MMT is 15:1.Photogenerated holes?h+?play a major role when H₂O₂ is not added,While hydroxyl radicals?·OH?play a major role when H₂O₂ is added.The results show that the incorporation of Fe3O4 and Na-MMT can not only improve the adsorption performance oforganic pollutants,but also achieve the solid-liquid separation by applying an external magnetic field and accelerate the rate of degradation by adding H₂O₂.