新型复合纳滤膜研究进展

纳滤膜因操作压力低、通量高、具有分离选择性以及运行成本较低等优势引起越来越多的关注,目前已在苦咸水脱盐、污水治理和海水淡化等领域发挥着重要作用。界面聚合作为常见的制备聚酰胺纳滤膜的方法,其聚合反应进程的调控可以有效地调节纳滤膜的微观结构,进而对其分离性能产生重要影响。本文从复合纳滤膜的结构入手,总结了当前常用的提升纳滤膜性能的改性方法,包括优化分离选择层、构建中间层、调整底膜结构三个方面,讨论了界面聚合过程反应单体、添加剂种类、制备条件等对分离层结构和分离性能的影响,并分析了底膜的孔径、孔隙率、亲疏水性等理化性质对复合膜性能的影响以及不同类型中间层的优缺点。在此基础上,总结了当前业界内亟待解决的问题,并对纳滤膜的未来发展趋势进行了展望。     

界面聚合在渗透汽化膜分离领域的应用进展

蒸馏、萃取等传统分离方法能耗高,污染环境,而渗透汽化由于低能耗、高效、环保等优势,为共沸物、近沸点混合物的分离提供了新的思路,但渗透汽化膜制备过程中面临的最大问题是获得性能优异且稳定的膜材料。在众多制备方法中,界面聚合法具有反应活性高、常温下生成膜层稳定、制备活性层致密等特点而备受关注。通过对界面聚合过程的调控,可以优化活性层,从而制备出兼具高通量和高选择性的渗透汽化膜。本文综述了界面聚合的原理、在渗透汽化膜制备方面的优势和近年来国内外的研究进展,详细阐述了复合膜制备过程中底膜的选择与改性、界面聚合条件的调控对渗透汽化膜结构和分离性能的影响机制,并对界面聚合制备渗透汽化膜所面临的问题及前景进行了总结与展望。     

基于界面聚合技术的复合纳滤膜改性研究进展

为了追求可持续发展，缓解缺水压力，水处理工艺的改进与研发就显得尤为重要。与传统水处理工艺相比，纳滤膜技术具有运行效率高、节约能源、设备紧凑、易于操作、不会产生二次污染以及自动化程度高等优点。该技术凭借这些优点及其独有的分离性能，在膜分离领域脱颖而出。在复合纳滤膜的构造上，界面聚合（IP）技术凭借操作简便、效率高、成膜稳定的特点成为了制备复合纳滤膜最常用的工艺。但是界面聚合的反应速度极快，怎样调控其反应过程进而提高纳滤膜的选择渗透性仍是一个巨大的挑战。此文主要在界面聚合技术的基础上，从基膜改性、两相单体改性、添加剂改性等三个方面综述了复合纳滤膜的改性研究进展，并对未来界面聚合技术的优化进行了展望。     

聚酰胺薄层复合膜的界面聚合制备过程调控研究进展

界面聚合法制备的聚酰胺薄层复合膜凭借着渗透通量以及分离选择性高、化学稳定性佳等优点在水处理等领域有着广泛应用。聚酰胺分离层的物理结构和化学性质决定着复合膜的分离性能,通过调控界面聚合过程来优化聚酰胺层的理化性质可提高复合膜的分离性能。本文聚焦聚酰胺分离层性质与复合膜性能之间的关系,从基膜改性、调控单体反应过程、聚酰胺层后处理三个方面综述了近年来调控界面聚合制膜过程的研究进展。通过分析单体传质对界面聚合反应的影响以及膜结构与性能间的构-效关系,总结了界面聚合制备聚酰胺复合膜的调控机理和方法,为进一步提升聚酰胺复合膜的分离性能提供理论依据和发展方向。     

界面聚合法制备耐酸纳滤膜的研究进展

强酸性环境中的分离过程在实际的工业生产中十分常见，纳滤分离技术具有效率高、能耗低、安全环保等优点，但是以聚酰胺为分离层材料的商品纳滤膜在强酸性环境中将发生降解，截留性能显著恶化。总结了近年来采用界面聚合法制备耐酸复合纳滤膜的研究进展，主要包括聚磺酰胺类、聚（三嗪）胺类和聚脲类复合纳滤膜，深入讨论了上述膜材料耐酸性提升的机理，分析了耐酸膜材料的结构设计规律，在此基础上提出了该领域的核心问题和发展方向，旨在为高性能耐酸复合纳滤膜的开发提供有益参考。     

原位界面聚合制备PVDF复合纳滤膜的研究

为改善聚偏氟乙烯(PVDF)复合纳滤膜性能，以掺入单体哌嗪(PIP)的铸膜液制备基膜，通过原位界面聚合快速制备复合纳滤膜，简化了制备程序。ATR-FTIR分析结果表明，基膜上成功生成聚酰胺(PA)层，SEM观察到PA层表面具有典型结节结构。得到的复合纳滤膜对Na₂SO₄截留率为95.59%,渗透通量为12.37 L/(m²·h·bar),远高于传统界面聚合制备的PVDF复合纳滤膜。72 h的持续测试结果表明该复合纳滤膜具有良好的长期稳定性。     

PA/ZIF-8/PVDF复合纳滤膜的制备及其性能

采用反向扩散法在聚偏氟乙烯(PVDF)基膜表面原位生长一层均匀、致密的金属有机骨架材料ZIF-8纳米晶体层,并进一步优化界面聚合反应,制备高性能聚酰胺(PA)/ZIF-8/PVDF复合纳滤膜.采用SEM、XRD、FTIR、AFM、XPS、水接触角测定仪以及固体表面Zeta电位仪对ZIF-8/PVDF复合膜及PA/ZIF-8/PVDF复合纳滤膜的组成、结构和形貌进行了表征,考察了ZIF-8亚层的生长对界面聚合反应、复合纳滤膜结构及性能的影响.结果表明,ZIF-8晶体亚层在PVDF膜表面的均匀连续生长改善了PA分离层与PVDF基膜的界面相容性,提高复合纳滤膜PA分离层的交联度.在0.6 MPa下,复合纳滤膜纯水通量可达24.05 L/(m2·h),对MgSO4、Na2SO4、NaCl和MgCl24种盐的截留率分别达到97.34％、93.57％、89.31％和85.16％,具有优异的抗污染性能.     

复合纳滤膜的研究进展

纳滤膜是孔径介于反渗透膜和超滤膜之间的一种分离膜,对二价、高价离子,及分子量大于200的有机物有较高脱除率,广泛用于海水淡化、城市污水处理等领域.纳滤复合膜是在微孔基膜表面复合上具有纳米级孔径的功能层,而获得的膜材料.本文介绍了一系列通过物理涂覆、接枝及界面聚合等方法制备的复合纳滤膜,综述了此领域的最新进展,并对纳滤膜的研究做出展望.     

用于混合一价盐分离的纳滤膜的制备及性能研究

针对有机颜料废水中单价相似离子（例如CH₃COO^-和Cl^-）分离难的问题,以表面活化能与脱水现象协同作用的分离机制为指导,在界面聚合中加入3,5-二氨基苯甲酸（DMA）来调控孔径、电性等性质,制备对醋酸根和氯离子具有高选择性的复合纳滤膜。XPS结果表明DMA参与界面聚合反应,形成疏松选择层;Zeta电位表明膜表面负电性增强。通过pH、操作压力等条件优化,得出0.6%（质量） DMA-TFC膜性能最佳,水通量较未改性复合膜提高44%,对于醋酸钠与硫酸钠的分离比达到15.0。本工作为相似离子分离纳滤膜的设计与制备提供了理论和实践基础,在颜料废水等水处理、物料分离等领域展现了良好的应用前景。     

耐溶剂复合纳滤膜的研究进展

耐溶剂纳滤是一种新型的膜分离技术,用于有机混合物的分离。商品耐溶剂纳滤膜大多是采用相转化法制备的整体皮层非对称膜,膜皮层较厚,通量较低。耐溶剂复合纳滤膜由基膜和分离层组成,具有薄皮层、高溶剂通量和高溶质截留率的优点。耐溶剂复合纳滤膜的制备与改性也因此成为近年来的研究热点。本文从界面聚合、表面涂覆、层层自组装、原位生长、有机-无机杂化和表面改性六个方面介绍耐溶剂复合纳滤膜的研究进展,最后对其发展前景进行展望。     

A design of composite hollow fiber membranes with tunable performance and reinforced mechanical strength

A new design of hollow fiber membranes with high mechanical strength, great surface area per volume ratio and tunable filtration performance is presented. This newly developed hollow fiber membrane was produced by an intensified production process, in which the processes of thermally induced phase separation (TIPS), non‐solvent induced phase separation (NIPS), and interfacial polymerization (IP) were combined. PVDF (polyvinylidene difluoride) hollow fiber membranes (produced by TIPS) were used as support substrates. Afterwards, PES (polyethersulfone) (made by NIPS) and PA (polyamide) layers (manufactured by IP) were coated one by one. The pure water permeability, molecular weight cut off (MWCO), salt rejection, tensile stress together with surface and cross‐sectional morphology indicate that the properties of the hollow fiber membranes can be easily adjusted from microfiltration‐like to nanofiltration‐like membranes only by varying the presence of the IP step and the concentration in the PES layer in the production system. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41247.     

压力驱动薄层复合膜中微孔基底的研究进展

压力驱动薄层复合膜（TFC）因其高分离效率和低能耗等优点,在水处理领域得到广泛应用。TFC膜的开发及性能提升可针对聚酰胺（PA）分离层和微孔基底两方面进行优化。其中,微孔基底对其上通过界面聚合（IP）形成的PA层的结构和分离性能具有重要影响。本文对NF/RO TFC膜中微孔基底的研究工作进行了评述。首先对两类微孔基底（相转化微孔基底和静电纺丝微孔基底）进行了概述,进而介绍了传统相转化微孔基底对IP过程的影响机理,并对相转化微孔基底的改性方法（聚合物共混、纳米材料掺杂、表面改性等）进行了总结,最后展望了共价有机框架（COFs）中间层表面改性微孔基底在构建高选择性、高渗透通量压力驱动TFC膜中的发展方向及面临的挑战。     

Polyethyleneimine-Mediated Polyamide Composite Membrane with High Perm-Selectivity for Forward Osmosis

Thin-film composite (TFC) membranes comprised of a polyamide (PA) selective layer upon a porous substrate dominate the forward osmosis (FO) membrane market. However, further improvement of perm-selectivity still remains a great challenge. Herein, a polyethyleneimine (PEI) interlayer is intentionally designed prior to interfacial polymerization (IP) to tailor the PA layer, which thus improves the separation performance. The PEI interlayer not only improves the substrate hydrophilicity for adsorbing more diamine monomer and controlling its release rate, but also participates in IP reaction by crosslinking with acyl chloride (TMC). Furthermore, it can decrease the electronegativity of the substrate for decreasing reverse salt diffusion. Consequently, a denser, thinner and smoother PA layer is formed due to the uniform distribution, controllable release of diamine monomer and the extra crosslinking between PEI and TMC. Furthermore, the PA layer becomes more hydrophilic with PEI involvement. As a result, the asprepared TFC membrane exhibits a favorable water flux of 16.1 L m⁻² h⁻¹ and an extremely low reverse salt flux (1.25 g m⁻² h⁻¹). Meanwhile, it achieves an excellent perm-selectivity with a ratio of water to salt permeability coefficient of 8.25 bar⁻¹. Moreover, it exhibits an outstanding antifouling capacity. The work sheds light on fabricating high perm-selective membranes for desalination.     

Green lignin-based polyester nanofiltration membranes with ethanol and chlorine resistance

As the main water treatment material, polymeric membranes inevitably suffer from membrane fouling. In this work, novel lignin-based polyester composite nanofiltration membranes (NFM) with ethanol and chlorine resistance were fabricated via interfacial polymerization. Lignin alkali (LA), a green lignin derivative, typically treated as chemical waste in the paper industry, was employed as the aqueous monomer, trimesoyl chloride (TMC) is served as the organic monomer. The structure and separation properties of the lignin-based NFM were studied, revealing that the dense polyester separation layer may show good performance for dye removal. The rejections of the optimized LA/TMC-3 membrane with an excellent permeation flux of 13.9 kg m^?2?h^?1 for rose Bengal sodium salt, brilliant blue, congo red, rhodamine B, MgSO₄, and NaCl are 97.6%, 97.3%, 97.8%, 71.34%, 51.4%, and 31.8%, respectively. Moreover, the LA/TMC-3 membrane also shows long-term tolerance in ethanol and sodium hypochlorite solution; the rejection of LA/TMC-3 to dye only decreases 8% after 8 days when immersed in alcohol, while the normalized rejection maintains 94% after 4000 ppm-hours of continuous exposure to chlorine. This lignin-based polyester membrane may broaden the sustainable utilization sphere of lignin derivatives, at that provide a referable direction for the development of membrane materials.     

Reducing active layer thickness of polyamide composite membranes using a covalent organic framework interlayer in interfacial polymerization

Polyamide(PA)-based thin-film composite membranes exhibit enormous potential in water purification, owing to their facile fabrication, decent performance and desirable stability. However, the thick PA active layer with high transport resistance from the conventional interfacial polymerization hampers their applications. The controllable fabrication of a thin PA active layer is essential for high separation efficiency but still challenging. Herein,a covalent organic framework TpPa-1 interlayer was firstly deposited on a polyethersulfone(PES) substrate to reduce the thickness of PA active layer in interfacial polymerization. The abundant pores of TpPa-1 increase the local concentration of amine monomers by adsorbing piperazine molecules, while hydrogen bonds between hydrophilic groups of TpPa-1 and piperazine molecules slow down their diffusion rate. Arising from those synergetic effects, the PA active layer is effectively reduced from 200 nm to 120 nm. By optimizing TpPa-1 interlayer and PA active layer, the water flux of resultant membranes can reach 171.35 L·m~(-2)·h~(-1)·MPa~(-1), which increased by 125.4% compared with PA/PES membranes, while the rejection rates of sodium sulfate and dyes solution remained more than 90% and 99%, respectively. Our strategy may stimulate rational design of ultrathin PA-based nanofiltration membranes with high performances.     

Preparation and properties of hollow fibre nanofiltration membrane with continuous coffee-ring structure

Polyamide(PA)hollow fibre composite nanofiltration(NF)membranes with a coffee-ring structure and beneficial properties were prepared by adding graphene oxide(GO)into the interfacial polymerization process.The presentation of the coffee-ring structure was attributed to the heterogeneous,finely dispersed multiphase reaction system and the“coffee-stain”effect of the GO solution.When the piperazine concentration was 0.4 wt-%,the trimesoyl chloride concentration was 0.3 wt-%,and the GO concentration was 0.025 wt-%,the prepared NF membranes showed the best separation properties.The permeate flux was 76 L·m^?2·h^?1,and the rejection rate for MgSO4 was 98.6%at 0.4 MPa.Scanning electron microscopy,atomic force microscopy,and attenuated total reflectance-Fourier transform infrared spectroscopy were used to characterize the chemical structure and morphology of the PA/GO NF membrane.The results showed that GO was successfully entrapped into the PA functional layer.Under neutral operating conditions,the PA/GO membrane showed typical negatively charged NF membrane separation characteristics,and the rejection rate decreased in the order of Na2SO₄>MgSO₄>MgCl₂>NaCl.The PA/GO NF membrane showed better antifouling performance than the PA membrane.     

Improved performance of polyamide nanofiltration membranes by incorporating reduced glutathione during interfacial polymerization

Inspired by the specific amino acid sequence Asn-Pro-Ala (NPA) of water channel aquaporins (AQPs), we fabricated polyamide (PA) nanofiltration (NF) membranes by introducing reduced glutathione (GSH) in interfacial polymerization (IP) method. Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectrometry (XPS), scanning electron microscope (SEM), atomic force microscopy (AFM), zeta potential and static water contact angle measurement were employed to characterize the chemical composition, morphology, electronegativity and hydrophilicity of the NF membranes. The water flux of GSH/PIP-TMC NF membrane reached 32.00 L m^-2 h^-1 at 0.2MPa, which was approximately twice than that of pristine PIP-TMC NF membrane when the ratio of GHS to piperazidine (PIP) was 40% during IP process. More water channels were built as GSH was embedded into PA layer. The fabricated NF membranes also took on potent rejection for dyes and Na₂SO₄. This study presents a simple and facile method to simulate water channels-based biological materials which may find potential application in water treatment.