聚乙烯亚胺有机溶剂纳滤膜微结构调控与性能优化

发布时间：2018-05-23 07:30

本文选题：聚乙烯亚胺 + 界面聚合　；参考：《郑州大学》2015年硕士论文

【摘要】：有机溶剂纳滤(OSN)是一种新兴的、压力驱动的膜分离过程,它主要适用于分子量范围在200-1000 Da之间的粒子与分子在有机相中的分离。由于其操作简便、绿色高效的优点,有机溶剂纳滤膜的发展受到广泛关注。因此,制备具有可控传递性能的有机溶剂纳滤膜,以适应复杂溶剂体系是目前有机溶剂纳滤技术的重要课题。有机溶剂纳滤膜的纳滤特性取决于膜微结构,而膜微结构又由膜材料和制备方法所决定。论文旨在利用交联与杂化耦合技术,通过界面聚合法将纳米颗粒/管填充到聚合物(聚乙烯亚胺,PEI)基质中调控其微结构,获得具有可控传递特性的有机溶剂纳滤复合膜。采用SEM、TEM、FTIR、TGA、接触角测试、溶剂吸附量和面积溶胀等对膜化学组成及其微结构进行系统表征,并测定膜的通量及截留率。论文主要探索膜微结构的形成条件和调控机制,以及有机溶剂纳滤膜的材料-微结构-纳滤特性之间的内在关系,获得高性能的有机溶剂纳滤膜的制备方法。具体研究工作如下:(1)受仿生矿化启示,PEI催化无机前体正硅酸乙酯(TEOS)水解原位生成无机纳米颗粒,随后交联制备出复合有机溶剂纳滤杂化膜。对所制备的膜进行系统表征和测试。结果显示:引入分散均匀的无机纳米颗粒,限制了链段运动性,提高膜的热稳定性和抗溶胀性,促进极性溶剂在膜中快速传递。同时,无机纳米颗粒与膜基质间良好的界面相容性,可提高膜的截留和长时稳定性。(2)环糊精(CDs)具有亲水外壁和疏水内腔,有利于构建亲/疏水通道来促进极性/非极性溶剂传递。本研究在PEI基质中引入不同尺寸和官能团的CDs,制备出双通道体系结构的复合有机溶剂纳滤膜,并对膜进行表征和测试。探索了多尺度协同效应及其作用机制,实现可控传递特性的有机溶剂纳滤膜的制备。结果显示:具备疏水内腔的CDs可在膜内形成疏水传递通道,有效提高了非极性溶剂的传递;随着CDs内腔尺寸的增大,有利于较小溶剂分子的传递。同时,通过调节改性CDs和PEI界面处的静电相互作用,可调控膜内自由体积,从而形成可控的亲水通道以供极性溶剂快速传递。其中,在10 bar下,当β-CD-NH含量增加到1.5 wt%时,异丙醇和正庚烷通量分别为41.6和24.2 L m-2 h-1,对PEG400的截留率高达94.9%以上。(3)埃洛石纳米管(HNTs)在膜中的定向排布有利于构建连续的溶剂传递通道。本研究将β-CDs改性的HNTs引入到PEI基质中,制备出高传递特性的复合有机溶剂纳滤膜。探索膜微结构的形成条件和过程机制,获得强化传递过程的理论和方法。结果显示:由于成膜过程和疏水相互作用,改性的HNTs垂直竖立在膜表面,可有效促进极性溶剂的传递。同时,改性后HNTs被高分子层覆盖,形成良好的界面兼容性,可提高膜的截留和长时稳定性。其中,在10 bar下,当HNTs-β-CD含量增加到2.0 wt%,异丙醇通量为67.8 L m-2 h-1,对PEG200的截留率高达94.3%。
[Abstract]:Organic solvent nanofiltration (OSNN) is a new, pressure-driven membrane separation process, which is mainly suitable for the separation of particles and molecules in the range of 200-1000 Da in organic phase. Due to its advantages of simple operation and green efficiency, the development of organic solvent nanofiltration membrane has received extensive attention. Therefore, the preparation of organic solvent nanofiltration membranes with controllable transfer properties to adapt to complex solvent systems is an important subject of organic solvent nanofiltration technology. The nanofiltration characteristics of organic solvent nanofiltration membrane depend on the membrane microstructure which is determined by the membrane material and preparation method. The aim of this paper is to control the microstructure of polymer (polyethylene imide PEI) matrix by interfacial polymerization by cross-linking and hybrid technology, and to obtain organic solvent nanofiltration composite membrane with controllable transfer property. The chemical composition and microstructure of the membrane were systematically characterized by means of SEMTEM FTIR TGA, contact angle test, solvent adsorption capacity and area swelling, and the flux and retention rate of the membrane were measured. In this paper, the formation conditions and regulation mechanism of membrane microstructure, and the intrinsic relationship between the material of organic solvent nanofiltration membrane, microstructure-nanofiltration characteristics, and the preparation method of high performance organic solvent nanofiltration membrane were studied. The specific research work is as follows: (1) PEI catalyzes the hydrolysis of inorganic precursor ethyl orthosilicate (TEOS) to form inorganic nanoparticles in situ, and then crosslinks to prepare composite organic solvent nanofiltration hybrid membrane. The prepared membranes were systematically characterized and tested. The results show that the introduction of inorganic nanoparticles with uniform dispersion limits the mobility of the chain segment, improves the thermal stability and anti-swelling property of the film, and promotes the rapid transfer of polar solvents in the film. At the same time, the good interfacial compatibility between inorganic nanoparticles and the membrane matrix can improve the membrane retention and long-term stability. 2) the cyclodextrin (CDss) has hydrophilic outer wall and hydrophobic cavity. It is advantageous to construct hydrophilic / hydrophobic channel to promote polar / nonpolar solvent transfer. In this study, the composite organic solvent nanofiltration membrane with two-channel system structure was prepared by introducing different size and functional groups into the PEI matrix, and the membrane was characterized and tested. The multi-scale synergistic effect and its mechanism were explored to prepare organic solvent nanofiltration membrane with controllable transfer characteristics. The results show that CDs with hydrophobic cavity can form hydrophobic transfer channel in the film, which can effectively improve the transfer of non-polar solvent, and with the increase of the size of CDs cavity, it is advantageous to the transfer of small solvent molecules. At the same time, by adjusting the electrostatic interaction between the modified CDs and the PEI interface, the free volume of the film can be regulated, thus a controllable hydrophilic channel can be formed for the rapid transfer of polar solvents. When the content of 尾 -CD-NH increased to 1.5 wt% at 10 bar, The flux of isopropanol and n-heptane were 41.6 and 24.2 L m-2 h-1, respectively, and the rejection rate of PEG400 was as high as 94.9%. In this study, 尾 -CDs modified HNTs was introduced into the PEI matrix to prepare a composite organic solvent nanofiltration membrane with high transfer characteristics. The formation conditions and process mechanism of membrane microstructure were explored, and the theory and method of enhanced transfer process were obtained. The results show that the modified HNTs is perpendicular to the surface of the film due to the interaction between film formation and hydrophobicity, which can effectively promote the transfer of polar solvents. At the same time, the modified HNTs is covered by polymer layer, forming good interfacial compatibility, which can improve the retention and long term stability of the membrane. At 10 bar, when the content of HNTs- 尾 -CD increased to 2.0 wt, the isopropanol flux was 67.8 L m ~ (-2) h-1, and the rejection rate of PEG200 was as high as 94.3%.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.893

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