【作者】 杨程；

【导师】 金君素；

【作者基本信息】 北京化工大学 ， 化学工程与技术， 2023， 硕士

【摘要】 染料废水的排放不仅对生态环境造成破坏,还对人类健康造成了威胁,高效降解染料废水备受关注。由于光催化氧化法具有反应条件温和、氧化能力强、处理范围广等优点,是一种具有广泛应用前景的染料降解方法。半导体材料和金属有机骨架（MOF）材料在光照下能产生强氧化性物质,是光催化剂的主要选择;其中铁基MOF（Fe-MOF）因其成本低廉、环境友好以及独特的理化特性备受青睐,但其对可见光吸收系数较弱,阻碍了其在光催化领域中的应用。本文通过Fe-MOF与聚合物载体或半导体材料复合,构建并制备了两种新型复合光催化材料NH₂-MIL-68(In_αFe_1-α)/PAA和BiOBr/NH₂-Fe-MOF,研究其结构、形貌、元素组成和光电化学性质,考察其对罗丹明B（Rh B）的光催化降解性能,阐释降解机理。论文主要内容如下:（1）采用高内相乳液模板法制备了球形载体材料聚丙烯酸酯微球（PAA）,再利用浸渍法和一步溶剂热法制备了双金属MOF复合光催化材料NH₂-MIL-68(In_αFe_1-α)/PAA。当前驱体溶液中铟铁离子摩尔比为7:3,催化剂用量为0.83 mg/L,Rh B初始浓度为10 mg/L时,在可见光下120min对Rh B的降解率为99.2%,反应速率常数达到0.03574 min^-1,并且光催化剂具有良好的循环稳定性。通过结构形貌表征,表明在PAA限域空间内原位生长的NH₂-MIL-68(In_αFe_1-α)的粒径减小了约90%,暴露出了更多金属中心活性位点并缩短了扩散距离;通过UV-vis DRS、瞬态光电流响应和电化学阻抗测试,表明了复合材料具有更高的可见光利用率以及电子-空穴对分离能力;通过自由基捕获实验、ESR测试证明了复合材料在光催化反应中主要的活性物质是h⁺,并提出了可能的光催化降解机理。（2）为了进一步提高光催化降解的效率,采用溶剂热法制备了BiOBr/NH₂-Fe-MOF复合光催化材料,该复合材料具有3D花状微球结构,实现了NH₂-Fe-MOF和BiOBr之间的紧密结合,形成了Type II异质结,增加了更多的活性位点,提高了可见光利用率,促进了电子-空穴对的分离。结果表明,当NH₂-Fe-MOF的摩尔含量为40%,催化剂用量为0.5mg/L,Rh B初始浓度为30 mg/L时,BiOBr/NH₂-Fe-MOF达到了对Rh B的最佳的降解性能,在可见光下40 min降解率为98.2%,其速率常数k值为0.08507 min^-1,优于目前报道的文献数据。光催化机理研究表明超氧自由基（·O₂^-）在光降解过程中发挥了主要作用。更多还原

【Abstract】 The discharge of dye wastewater not only damages the ecological environment but also poses a threat to human health.Efficient degradation of dye wastewater is receiving increasing attention.Due to its mild reaction conditions,strong oxidation capacity,and wide treatment range,photocatalytic oxidation is a dye degradation method with broad application prospects.Semiconductor materials and metal-organic framework（MOF）materials can produce strongly oxidizing substances under light irradiation and are the main choices for photocatalysts.Among them,iron-based MOF（Fe-MOF）is favored due to its low cost,environmental friendliness,and unique physical and chemical properties.However,its weak visible light absorption coefficient hinders its application in the field of photocatalysis.In this paper,two new composite photocatalytic materials NH₂-MIL-68(In_αFe_1-α)/PAA and BiOBr/NH₂-Fe-MOF were prepared by combining Fe-MOF with polymer carriers or semiconductor materials.Their structures,morphologies,elemental compositions,and photoelectrochemical properties were studied,and their photocatalytic degradation performance of Rhodamine B（Rh B）was investigated to explain the degradation mechanism.The main contents of the paper are as follows:（1）Spherical carrier material polyacrylate（PAA）microsphereswere prepared by high internal phase emulsion templating method,and NH₂-MIL-68(In_αFe_1-α)/PAA was prepared by impregnation method and one-step solvothermal method to prepare bimetallic MOF composite photocatalytic material.When the molar ratio of indium and iron ions in precursor solution was 7:3,the catalyst dosage was 0.83 mg/L,and the initial concentration of Rh B was 10 mg/L,the degradation rate of Rh B under visible light for 120 min was99.2%,and the reaction rate constant reached 0.03574 min^-1.The photocatalyst had good cyclic stability.The structural morphology characterization showed that the particle size of NH₂-MIL-68(In_αFe_1-α)grown in-situ within the PAA confinement space was reduced by about 90%,exposing more metal center active sites and shortening the diffusion distance.UV-vis DRS,transient photocurrent response,and electrochemical impedance spectroscopy test indicated that the composite material had higher visible light utilization and electron-hole pair separation ability.Free radical capture experiments and ESR testing demonstrate that the main active species in the photocatalytic reaction of the composite material was h⁺,and a possible photocatalytic degradation mechanism was proposed.（2）In order to further improve the efficiency of photocatalytic degradation,BiOBr/NH₂-Fe-MOF composite photocatalytic materials were prepared using a solvothermal method.The composite material had a 3D flower-like microstructure,which achieved a tight combination between NH₂-Fe-MOF and BiOBr,forming a Type II heterogeneous structure,increasing more active sites,improving the utilization of visible light,and promoting the separation of electron-hole pairs.The results showed that when the molar content of NH₂-Fe-MOF was 40%,the catalyst dosage was 0.5 mg/L,and the initial concentration of Rh B was 30 mg/L,BiOBr/NH₂-Fe-MOF achieved the best degradation performance for Rh B,with a degradation rate of 98.2%in 40 min under visible light.Its rate constant k value was 0.08507 min^-1,which was better than the literature data currently reported.The study of photocatalytic mechanism showed that superoxide radicals（·O₂^-）played a major role in the photocatalytic degradation process.更多还原