【作者】 刘昕；

【导师】 吕东伟；

【作者基本信息】 哈尔滨工业大学 ， 土木工程， 2023， 硕士

【摘要】 近年来,催化膜同高级氧化工艺的结合使用越来越被关注,发展成为有效的水中有机物处理前沿技术之一,其中催化膜耦合臭氧氧化系统被认为是有前途的商业水处理系统。将催化膜同臭氧催化氧化工艺结合,应用于对小分子有机物的有效去除,一方面能够避免臭氧催化氧化过程传质效率低和催化剂的回收问题,另一方面也能够实现传统低压膜对小分子污染物的去除。采用锰氧化物和有机物造孔剂为制膜原材料,通过球磨得到制膜粉体,通过干压结合高温烧结,一步法直接制备MnO_x平板催化膜,其在高温烧结过程中发生还原,膜的孔径结构、元素状态等都会发生变化。进而改变催化膜烧结温度实现对MnO_x催化膜形貌结构、晶相组成、元素价态和表面缺陷等方面的调控,将使用扫描电子显微镜、X射线衍射、X射线光电子能谱、电子顺磁共振等多种仪器表征催化膜,考察烧结温度对膜性质的调控作用。发现在烧结温度为500℃、700℃、900℃时,烧结温度升高,膜内孔径减小,相应膜通量降低,Mn²⁺与Mn³⁺含量比增大,表面晶格氧与氧空位的含量比下降。其次,以阿特拉津为目标污染物,于催化膜耦合臭氧催化氧化体系中,验证了MnO_x平板催化膜具有催化活性。同时对比不同烧结温度对膜的催化效能的调控,其中相比500℃膜和700℃膜,900℃膜具有最佳的催化活性,平均孔径约738.85 nm、Mn²⁺含量为70.99%、氧空位含量为68.21%,三者共同对催化膜的活性产生影响。进行单因素影响实验,考察不同条件对催化效能的影响。在实验范围内,提高臭氧投量,降低底物浓度或者增加进料液在膜内的停留时间都与MnO_x催化膜对阿特拉津的去除呈正相关关系。通过电子顺磁共振仪器和活性氧淬灭实验,验证催化降解过程存在·O₂^-、·OH及¹O₂,说明降解过程既存在自由基路径也存在非自由基路径。根据液质联用分析产物,推断阿特拉津降解可能的路径。此外,对使用后催化膜的性质分析表征以探究反应机制,反应体系Mn²⁺/Mn³⁺的电子转移和氧空位也在催化反应中发挥重要作用。MnO_x平板催化膜的制备能为金属氧化物类无机催化膜内的金属元素价态和氧元素状态调控提供一种可操作性强的方法。该膜实现了对小分子污染物的有效去除,结合离子溶出情况和江水背景下更佳的催化效果,展现了实际应用潜能。更多还原

【Abstract】 The combination of catalytic membranes and advanced oxidation processes has received increasing attention in recent years and developed into one of the effective cutting-edge technologies for organic matter treatment in water.Among them,the catalytic membrane coupled ozone oxidation system was considered the promising commercial water treatment system.The combination of catalytic membrane and ozone catalytic oxidation process can effectively remove small molecule organic compounds.On the one hand,it can avoid low mass transfer efficiency and catalyst recovery issues in the ozone catalytic oxidation process,and on the other hand,it can also achieve the removal of small molecule pollutants by traditional low-pressure membranes.Manganese oxide and organic pore forming agents were used as raw materials for membrane preparation.The membrane powder was obtained through ball milling,and the MnO_x flat catalytic membrane is directly prepared through a one-step method of dry pressing combined with high-temperature sintering.During the high-temperature sintering process,it underwent reduction,and the pore structure,elemental state of the membrane would change.Furthermore,by changing the sintering temperature of the catalytic membrane,the morphology,structure,crystal phase composition,elemental valence states,and surface defects of the MnO_xcatalytic membrane could be controlled.Various instruments such as scanning electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,electron paramagnetic resonance,etc.would be used to characterize the catalytic membrane and investigate the regulatory effect of sintering temperature on membrane properties.It was found that at sintering temperatures of 500℃,700℃,and 900℃,the sintering temperature increased,the pore size inside the membrane decreased,and the corresponding membrane flux decreased.The content ratio of Mn²⁺to Mn³⁺increased,and the content ratio of surface lattice oxygen to oxygen vacancies decreased.With atrazine as the target pollutant,the catalytic activity of MnO_x flat catalytic membrane was verified in a catalytic membrane coupled ozone catalytic oxidation system.At the same time,the control of different sintering temperatures on the catalytic efficiency of the membrane was compared.Among them,compared to the500℃and 700℃membranes,the 900℃membrane had the best catalytic activity,with an average pore size of about 738.85 nm,a Mn²⁺content of 70.99%,and an oxygen vacancy content of 68.21%.The average pore size,Mn²⁺/Mn³⁺content ratio,and oxygen vacancy content all together had an impact on the catalytic membrane activity.A single factor influence experiment was conducted to investigate the effects of different conditions on catalytic efficiency.Within the experimental range,increasing ozone dosage,reducing substrate concentration,or increasing the residence time of the feed liquid in the membrane were positively correlated with the removal of atrazine by MnO_x catalytic membrane.Through electron paramagnetic resonance instruments and reactive oxygen quenching experiments,the presence of·O₂^-,·OH,and ¹O₂ in the catalytic degradation process was verified,indicating that there are both free radical and non free radical pathways in the degradation process.Based on the analysis of the products by liquid chromatography-mass spectrometry,a possible pathway for the degradation of atrazine was inferred.In addition,the properties of the catalytic membrane after use were analyzed and characterized to explore the reaction mechanism.The electron transfer and oxygen vacancies of the reaction system Mn²⁺/Mn³⁺also played an important role in the catalytic reaction.The preparation of MnO_x flat catalytic membranes can provide a highly operational method for regulating the valence states of internal metal elements and oxygen element states of metal oxide inorganic catalytic membranes.This membrane has achieved effective removal of small molecule pollutants.Combining ion dissolution and better catalytic performance under river water background,it has demonstrated practical application potential.更多还原