【作者】 李静；

【导师】 吴勉；

【作者基本信息】 中国矿业大学 ， 化学， 2025， 硕士

【摘要】 油水乳液中液滴粒径小、稳定性高,处理难度大。膜分离技术具有分离效率高、能耗低、操作简便等优点,被认为是深度处理含油废水（特别是粒径小于20微米的油水乳液）的有效技术之一。近年来,具有超浸润特性的多孔膜在油水分离领域备受关注。金属有机框架材料（MOFs）因其比表面积高、孔道均匀和表面化学性质可调,成为构筑高性能分离膜的理想材料。其中,沸石咪唑酯骨架材料ZIF-8具有化学性质稳定、孔隙率高和易于功能化修饰的特点,在膜分离领域展现出巨大的潜力。为了提高ZIF-8膜的通量,采用单宁酸（TA）表面功能化刻蚀ZIF-8,制备具有孔腔结构和表面有丰富羟基的TA@ZIF-8复合膜。通过优化TA掺杂量,调控复合膜的微结构及润湿性能,并对其水包油型乳液的分离性能进行了研究。为了应对复杂的油水混合体系,构建了具有非对称浸润性能的Janus ZIF-8膜,按需分离水包油型乳液或油包水型乳液。主要研究内容及结论如下:（1）为了在保持高选择性的前提下,提高ZIF-8膜的通量,首先采用刻蚀的方法制备了TA修饰的ZIF-8颗粒,然后通过真空沉积策略,制备了TA@ZIF-8复合膜,该膜具有超亲水性和水下超疏油性,可用于高效分离水包油型（O/W）乳液。TA的修饰不仅在ZIF-8内部形成了大尺寸的孔腔,而且在ZIF-8表面引入了丰富的羟基,促进了溶剂分子的渗透。同时,乳化液滴与复合膜表面羟基之间的氢键相互作用能破坏乳化液滴的界面膜,实现破乳过程;然后小油滴碰撞聚结形成大油滴,实现油水的高效分离。基于尺寸筛分效应,复合膜具有较高的分离效率,对一系列O/W乳液的渗透通量为3306 L m^-2 h^-1 bar^-1,截油率高达99.8%。此外,由于TA与ZIF-8中暴露的Zn中心之间的配位相互作用,复合膜具有优异的机械和化学稳定性,经过10次循环过滤后,仍表现出稳定的分离性能。由于膜的亲水性形成的水合层效应加上相对光滑的膜表面,提高了膜的抗污染性能,在实际含油废水处理中表现出很大的应用潜力。（2）为了应对复杂的油水乳液分离体系,提出了具有非对称浸润性的Janus膜。首先分别采用（3-氨基丙基）三乙氧基硅烷（APTES）和聚乙烯吡咯烷酮（PVP）对ZIF-8颗粒进行疏水和亲水改性,然后将改性后的粉末分别喷涂在不锈钢网（SSM）两面,制备了具有非对称浸润性的Janus膜。疏水改性能大大降低表面能,使APTES@ZIF-8表现出超疏水性（水的接触角为152°）,亲水基团的引入使PVP@ZIF-8界面表现出超亲水-水下超疏油性（水下油的接触角为153°）。Janus ZIF-8膜独特的微纳分级结构与非对称浸润性产生的润湿性梯度的协同作用增强了破乳能力。破乳后的液滴在微纳结构表面快速聚结,实现高效的油水分离。该Janus ZIF-8膜在重力驱动下表现出优异的分离性能,亲水面对一系列O/W乳液的渗透通量为850 L m^-2 h^-1,截油率达99.1%以上;疏水面对一系列W/O乳液的渗透通量为267 L m^-2 h^-1,截水率达99%以上。此外,制备的Janus膜经过10次循环O/W和W/O乳液过滤、50次砂纸磨损和24 h强酸/碱和高浓度盐浸泡后,依然表现出稳定的分离性能。因此,快速喷涂法制备的超浸润Janus膜能用于按需分离O/W乳液或W/O乳液,为复杂油水混合体系的分离提供了新思路。本文包含图58幅,表4个,参考文献125篇。更多还原

【Abstract】 The droplet in oil-water emulsion has small particle size and high stability,and it is difficult to treat.Membrane separation technology has the advantages of high separation efficiency,low energy consumption,and simple operation,and is considered one of the effective technologies for deep treatment of oily wastewater（especially oil-water emulsion with particle size less than 20 microns）.In recent years,porous membranes with super-wetting properties have attracted much attention in the field of oil-water separation.Metal-organic frame materials（MOFs）are ideal materials for high-performance separation membranes because of their high surface area,uniform pores,and adjustable surface chemistry.Among them,the zeolite imidazolate skeleton material ZIF-8 has the characteristics of chemical stability,high porosity,and easy functional modification,which shows great potential in the field of membrane separation.To increase the flux of ZIF-8 membrane,the TA@ZIF-8 composite membrane with pore structure and abundant hydroxyl groups was prepared by surface functionalization of tannic acid（TA）to etch ZIF-8.The microstructure and wettability of the composite membrane were regulated by optimizing the doping amount of TA,and the separation performance of the oil-in-water emulsion was studied.To cope with the complex oil-water mixing system,Janus ZIF-8 membrane with asymmetric infiltrating property was constructed to separate oil-in-water emulsion or water-in-oil emulsion as needed.The main research contents and conclusions are as follows:（1）To improve the flux of ZIF-8 membrane on the premise of maintaining high selectivity,TA modified ZIF-8 particles were first prepared by the etching method,and then TA@ZIF-8 composite membrane was prepared by the vacuum deposition strategy.The membrane has super hydrophilic and underwater super oleophobic properties and can be used for efficient separation of oil-in-water（O/W）emulsions.The modification of TA not only formed a large-sized cavity inside ZIF-8 but also introduced a rich hydroxyl group on the surface of ZIF-8,promoting the penetration of solvent molecules.At the same time,the hydrogen bond interaction between the droplet and the hydroxyl group on the surface of the composite membrane can destroy the interface film of the droplet and realize the demulsification process.Then small oil droplets collide and coalesce to form large oil droplets,achieving efficient separation of oil and water.Based on the sisioning effect,the composite membrane has a high separation efficiency,the permeability of a series of O/W emulsions is 3306 L m^-2 h^-1 bar^-1,and the oil intercession rate is as high as 99.8%.In addition,due to the coordination interaction between TA and the exposed Zn center in ZIF-8,the composite membrane has excellent mechanical and chemical stability,and still shows stable separation performance after10 cycles of filtration.Due to the hydrophilic effect of the membrane and the relatively smooth surface of the membrane,the anti-pollution performance of the membrane is improved,which shows great application potential in the actual treatment of oily wastewater.（2）In order to cope with the complex oil-water emulsion separation system,the asymmetric infiltrating Janus membrane was proposed.First,the ZIF-8 particles were modified with（3-amino-propyl）triethoxysilane（APTES）and polyvinylpyrrolidone（PVP）respectively,and then the modified powder was sprayed on both sides of stainless steel mesh（SSM）to prepare the asymmetric infiltrating Janus membrane.The hydrophobic modification property greatly reduces the surface energy,making APTES@ZIF-8 appear super hydrophobic（contact angle of water is 152°）,and the introduction of hydrophilic groups makes PVP@ZIF-8 appear super hydrophilic-underwater super oleophobic（contact angle of underwater oil is 153°）.The synergistic effect of Janus ZIF-8 membrane unique micro-nano hierarchical structure and its asymmetric wettability gradient enhances the demilking ability.After demulsification,the droplets coalesce rapidly on the surface of micro-nano structure to achieve efficient oil-water separation.The prepared Janus ZIF-8 membrane showed excellent separation performance under gravity drive,and the permeability of hydrophilic water surface to a series of O/W emulsions was 850 L m^-2 h^-1,and the oil intercepting rate was more than 99.1%.The permeation flux of hydrophobic surface to a series of W/O emulsions is 267 L m^-2 h^-1,and the water interception rate is more than 99%.In addition,the prepared Janus membrane showed stable separation performance after 10 cycles of O/W and W/O emulsion filtration,50 cycles of sandpaper wear,and 24 hours of immersion in strong acids/bases and high concentrations of salt.Therefore,the super-wetted Janus membrane prepared by the rapid spraying method can be used to separate O/W emulsions or W/O emulsions on demand,providing a new idea for the separation of complex oil-water mixing systems.There are 58 figures,4 tables,and 125 references included in this thesis.更多还原