芳香聚酰胺系列反渗透复合膜的初步研究

本文研究了以芳香族聚酰胺为超薄层,聚砜多孔膜为支撑膜的反渗透复合膜,简要地讨论了成膜过程中的各种因素对膜性能的影响,如胺类和酰氯的种类、比例和浓度,以及反应时间等。探讨了膜性能与进料浓度的关系,膜的低压和耐氯性能及膜的电学性能和膜结构。实验表明选择不同胺类和酰氯,控制一定的成膜工艺条件,可制出具有各种不同反渗透特性的复合膜。     

FM-100反渗透复合膜的研制

糠醇和预聚体M在聚砜支撑膜上进行共缩聚反应,制备了FM-100反渗透复合膜。研究了预聚体M和催化剂的用量、聚合反应的温度以及添加剂的性质等对FM-100复合膜反渗透性能的影响。同时,研究了供料液浓度和pH值等对FM-100复合膜性能的影响,考查了膜的抗氯性、抗氧化性和长期运转的稳定性。     

聚酯酰胺反渗透复合膜的制备及其表征

以间苯二胺、氨基葡萄糖与均苯三甲酰氟为反应物，在聚砜基膜上用界面聚合法制备聚酯酰胺反渗透复合膜。用红外光谱仪（FT-IR）和扫描电子显微镜（SEM）及原子力显微镜（AFM）对所制备膜的结构和形态进行表征。红外光谱的结果表明有聚酰胺和聚酯结构的生成，扫描电镜结果显示复合膜表面呈明显的峰谷状结构，原子力显微镜分析结果表明聚酯酰胺膜表面粗糙度较聚酰胺膜表面粗糙度大。实验考察了界面聚合反应中的水相单体配比对所制备复合膜分离性能的影响；并进一步考察了操作条件及物料性质对制备的聚酯酰胺反渗透复合膜分离性能的影响。研究表明：随水相中氨基葡萄糖配比的增加，复合膜的脱盐率下降，通量上升。聚酯酰胺反渗透复合膜在1．6MPa操作压力下水通量达到27．4L／m^2·h以上，对2000mg／L的NaCl、KCl、MgCl2、Na2SO4、MgSO4等无机盐的脱盐率均在97．5％以上。     

芳香聚酰胺反渗透复合膜界面聚合影响因素分析

目前应用较为广泛的反渗透复合膜的制备方法是由单体间苯二胺和均苯三甲酰氯在超滤支撑膜上界面聚合生成聚酰胺脱盐皮层。该制膜方法影响因素众多,能够影响反渗透复合膜分离性能的因素主要有支撑膜的结构和化学性质、单体结构和浓度、添加剂的选择、反应温度和时间、后处理温度和时间等。对界面聚合的一些主要影响因素进行分析。     

超低压反渗透复合膜研制

研究了以聚砜作为支撑层,间苯二胺和均苯三甲酰氯为主要聚合单体,并使用多种添加剂,经界面聚合制备超低压反渗透复合膜,探讨了超低压反渗透复合膜制备的成膜规律和主要影响因素：底膜支撑层、水相、有机相、添加剂的种类,聚合时间和热处理温度等。试验结果表明,在适当的试验条件下制备的超低压反渗透复合膜,具有优良的分离性能。在1.0MPa测试压力,4L/min流速下,对温度25℃、浓度1500mg/L的氯化钠溶液,脱盐率可以达到99.2%,水通量达到50L/m2.h。     

PSF支撑层结构对PDMS复合膜渗透汽化性能的影响

以4种不同结构的聚砜(PSF)作为支撑层,制备PDMS/PSF渗透汽化复合膜,考察其用于乙醇/水体系的分离性能,以研究支撑层结构对渗透汽化复合膜分离性能的影响。采用SEM和EDX分析复合膜表层结构,结果表明,支撑层结构几乎不影响复合膜的选择性,但对膜通量有较大影响,特别是支撑层的表面结构对复合膜性能的影响比断面结构更明显。     

聚砜/改性碳纳米管复合膜的制备及亲水性能

利用浸没沉淀相转化法,以聚砜(PSF)为膜材料,羧基化碳纳米管(MWCNTs-COOH)为添加剂,聚乙烯吡咯烷酮(PVP)为致孔剂,N,N-二甲基乙酰胺(DMAc)为溶剂,制备了聚砜/多壁碳纳米管复合膜,系统研究了制备复合膜时碳纳米管的添加量、预挥发时间以及凝固浴组成对其结构和性能的影响。实验结果表明,添加MWCNTs-COOH后,复合膜的亲水性能和抗污性能显著提高,同时复合膜的力学性能也明显增强。复合膜的 SEM 照片显示,随预挥发时间的延长和凝固浴中DMAc 质量分数的增加,复合膜断面由指状孔结构向海绵状孔结构过渡;复合膜的水通量下降,截留率上升。     

反渗透复合膜研究(Ⅱ)初生态膜的原位改性

界面聚合是制备超薄复合膜是通过两种互不相溶的单体溶液在多孔支撑的表面进行聚合,再经热处理,洗涤等工艺后得到超薄复合膜。初生态膜(IniM)是指完成界面聚合反应而未经后处理（热处理,洗涤等）的膜。采用间苯二胺和均苯三甲酰氯通过在多孔聚砜膜上界面聚合得到初生态反渗透复合膜,再用四乙烯五胺对初生态膜进行表面原位改性,经后处理得到改性反渗透复合膜。对改性反渗透复合膜面XPS分析结果为：改性膜表面的O/N比明显低于未改性的,这说明四乙烯五胺通过反应接枝在膜表面;同时,改性膜面接触角大于未改性膜的,进一步证明了这一点。脱盐性能测试结果为：改性反渗透复合膜的水通量和NaCl脱除率随着进水pH值的增大而减小,这与未改性的反渗透复合膜变化趋势完全相反;这是因为改性反渗透复合膜面含有氨基（—NH₂）或亚胺基（=NH）,当pH值增大时,其与水的亲和力减小;而未改性的反渗透复合膜表面含有羧基（—COOH）, 当pH值增大时,其与水的亲和力增大。     

海水淡化反渗透复合膜元件的制备

论述了海水淡化膜元件制作过程中，支撑底膜的孔结构、水相及有机相单体的种类、浓度，界面聚合的时间、热处理温度以及产业化生产过程中各个工艺条件的控制对海水淡化反渗透复合膜性能和均匀性的影响；介绍了膜元件卷制的工艺对元件性能的影响以及国产海水淡化反渗透复合膜元件在实际工程中的应用情况及与进口膜元件的性能对比。     

PFI型复合反渗透膜的性能特性

在常温常湿下连续制得的增强聚砜膜具有不对称结构,平均孔径300—1500A,且耐热性和化学稳定性好,适宜于做复合膜的支撑膜。以增强聚矾膜为支撑膜,采用就地聚合技术制备了PFI型复合膜。本文对操作压力,供料液温度,供料液浓度和pH值等对PFI型膜性能的影响进行了试验,同时考查了其抗氧化性,抗氯性,长期贮存和长期运转的稳定性。     

Effect of surface properties of polysulfone support on the performance of thin film composite polyamide reverse osmosis membranes

In this work, influence of initial conditions and surface characteristics of porous support layer on structure and performance of a thin film composite (TFC) polyamide reverse osmosis (RO) membrane was investigated. The phase inversion method was used for casting of polysulfone (PSf) supports and interfacial polymerization was used for coating of polyamide layer over the substrates. The effect of PSf concentrations that varied between 16 wt % and 21 wt %, and kind of the solvent (DMF and NMP) used for preparation of initial casting solution were investigated on the properties of the final RO membranes. SEM imaging, surface porosity, mean pore radius, and pure water flux analysis were applied for characterization of the supports. The substrate of the membrane, which synthesized with 18 wt % of PSf showed the most porosity and the synthesized RO membrane had the lowest salt rejection. In case of the solvents, the membranes synthesized with DMF presented better separation performance that can be attributed to their lower thickness and sponge‐like structure. The best composition of support for TFC RO membranes reached 16 wt % PSf in DMF solvent. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44444.     

Preparation,characterization, and application of thin film composite nanofiltration membranes

The active aromatic polyamide layers of thin film composite nanofiltration (NF‐TFC) membranes were prepared via interfacial polymerization (IP) from three different types of polyamine: p‐phenylenediamine (PPD), m‐phenylenediamine (MPD), or piperazine (PRP), and trimesoyl chloride (TMC) on polysulfone/sulfonated polysulfone (PSf/SPSf) alloy substrates. Chemical components, cross section structures, and thermal properties of the polyamide active layers and the bulk membranes, characterized by Fourier transfer IR spectroscopy and attenuated total reflection IR spectroscopy, scanning electron microscopy, and differential scanning calorimetry and thermogravimetry, respectively, revealed an interpenetrating layer between the polyamide active layer and the substrate. A ridge–valley structural active layer was formed on the PSf/SPSf substrate for the NF‐TFC membrane with a thick polyacrylamide (PA) layer. Compared with the NF‐TFC membranes on PSf substrates, those on PSf/SPSf alloy substrates had a higher permeability without losing the selectivity by introducing the hydrophilic SPSf into the hydrophobic PSf substrates. The binding between the modified substrate and the active PA layer was also improved. Good separation performances using these NF‐TFC membranes were obtained in the polyvalent ion separation, the ground water softening, and the treatment of wastewater from adipic acid plants in a wide pH range. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1251–1261, 2005     

Characterization of composite membranes by their non-equilibrium thermodynamic transport parameters

Composite reverse osmosis membranes were prepared by interfacially polymerizing aromatic polyamide discriminating layers on the inside surface of microporous polyethersulfone hollow fibers and on the surface of flat sheet polysulfone ultrafilters. The salt rejection and flux of these membranes were measured at various feed pressures. From these measurements, the membrane reflection coefficients, salt permeances and hydraulic permeances were estimated. Neither the polysulfone ultrafilters nor the microporous polyethersulfone hollow fibers possessed any inherent salt rejecting capability. Both had a hydraulic permeance at least two orders of magnitude greater than that of the respective composite membranes. Consequently, it was concluded that the estimated transport parameters for both composite membranes were characteristics exclusively of thier polyamide discriminating layers. Comparison of these transport parameters generated insight into structural and functional aspects of the membrane that could not be visualized by scanning electron microscopy.     

Forward osmosis water desalination: Fabrication of graphene oxide-polyamide/polysulfone thin-film nanocomposite membrane with high water flux and low reverse salt diffusion

This paper investigates the synthesis of graphene oxide (GO)-incorporated polyamide thin-film nanocomposite (TFN) membranes on polysulfone substrate for forward osmosis applications. The GO nanosheets were embedded into polyamide layer using different concentrations (0.05?0.2 wt%). The results represented the alteration of polyamide surface by GO nanosheets and enhancing the surface hydrophilicity by increasing the GO loading. The results showed that the water flux for 0.1 wt% GO embedded nanocomposite (TFN) membrane was 34.7 L/m² h, representing 90% improvement compared to the thin-film composite, while the salt reverse diffusion was reduced up to 39%.     

添加剂对聚砜膜结构和性能的影响

通过浸没沉淀相转化法制备聚砜超滤膜,分别以高分子聚乙烯基吡咯烷酮（PVP-K30,PVP-K90）、聚乙二醇（PEG-6000,PEG-20000）和小分子氯化锌（ZnCl2）、丙酸（AS）6种物质作为制备聚砜超滤膜的添加剂,含量均为10%。并对聚砜超滤膜的断面结构、纯水通量、牛血清蛋白（BSA）截留率、孔隙率及平衡水含量等5项性能进行了测试及表征。由断面结构可以看出,PVP-K90作为添加剂时,制得膜的断面完全为海绵状结构,其它添加剂制得膜断面中均有指状孔结构;PVP-K30作为添加剂时制得膜的纯水通量最大;丙酸作为添加剂制得膜的BSA截留率最高;聚乙烯基吡咯烷酮（PVP）和聚乙二醇（PEG）制得膜的平衡水含量及总孔隙率均较高,但闭孔也较多。     

Thin-film composite forward osmosis membranes with substrate layer composed of polysulfone blended with PEG or polysulfone grafted PEG methyl ether methacrylate

To advance commercial application of forward osmosis (FO), we investigated the effects of two additives on the performance of polysulfone (PSf) based FO membranes: one is poly(ethylene glycol) (PEG), and another is PSf grafted with PEG methyl ether methacrylate (PSf-g-PEGMA). PSf blended with PEG or PSf-g-PEGMA was used to form a substrate layer, and then polyamide was formed on a support layer by interfacial polymerization. In this study, NaCl (1 mol?L⁻¹) and deionized water were used as the draw solution and the feed solution, respectively. With the increase of PEG content from 0 to 15 wt-%, FO water flux declined by 23.4% to 59.3% compared to a PSf TFC FO membrane. With the increase of PSf-g-PEGMA from 0 to 15 wt-%, the membrane flux showed almost no change at first and then declined by about 52.0% and 50.4%. The PSf with 5 wt-% PSf-g-PEGMA FO membrane showed a higher pure water flux of 8.74 L?m⁻²?h⁻¹ than the commercial HTI membranes (6–8 L?m⁻²?h⁻¹) under the FO mode. Our study suggests that hydrophobic interface is very important for the formation of polyamide, and a small amount of PSf-g-PEGMA can maintain a good condition for the formation of polyamide and reduce internal concentration polarization.     

Influence of metal salts in reaction medium on performance enhancement of novel aliphatic–aromatic-based polyamide thin-film composite osmosis membranes

In this study, we report an easy and novel way to develop high flux aliphatic–aromatic-based thin-film composite (TFC) polyamide osmosis membranes by addition of inorganic metal salts with amine reactants in the reaction system of polyethylene imine (PEI) and 1,3-benzene dicarbonyl chloride. Inorganic metal salts like CuSO₄, NiSO₄, MgSO₄, and Al₂(SO₄)₃ added to block some of the amine groups of PEI through complexation which in turn changes the polycondensation reaction kinetics of amine acid chloride reaction. The prepared membranes were characterized using water contact angle and atomic force microscopy studies and the performances were evaluated both in reverse osmosis and forward osmosis mode. In presence of metal salts in reaction interface, the performance of TFC membranes was greatly enhanced and the optimum metal salt concentration was identified for individual metal salts for maximum performance enhancement. The effects of different anions for same metal ion and different molecular weight of PEI were evaluated on composite polyamide membrane performances. Water permeability (flux) of 63.48 L m^?2 h^?1 was achieved upon inorganic salt addition compared to the unmodified TFC membranes with flux of 42.1 L m^?2 h^?1 at similar salt rejection of ~95%. Based on the new findings, a conceptual model was proposed to explain the role of metal ion in amine solution on the resulting characteristics of aromatic–aliphatic type polyamide–polysulfone composite membrane.     

Chiral separation of D,L‐serine racemate using a molecularly imprinted polymer composite membrane

Molecularly imprinted (MIP) composite membranes were prepared using conventional interfacial polymerization technique that has been often used for the preparation of reverse osmosis (RO) membrane. Target molecules (D ‐serine) were used together with the piperazine (PIP) and Trimesoyl chloride (TMC) for the interfacial polymerization of the active layer with chiral spaces in it on the surface of the polysulfone ultrafiltration membranes. After formation of the polyamide composite membranes, the target molecules in the active layers were removed and MIP composite membranes were prepared. The MIP membranes prepared so were then characterized with analytical methods and proved to be effective for the selective permeation of D ‐serine. When serine racemate was used for optical resolution, the diffusion rate of the D ‐serine appeared to be faster than that of the L ‐serine and in permeates, the concentration of the D ‐serine increased with operation time. When the operating time reached 60 h, enantiomeric excess (% ee) of the serine mixture in permeates became about 80%. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1866–1872, 2007     

Synthesis and transport properties of thin film composite membranes. II. Preparation of sulfonated poly(phenylene oxide) thin film composite membranes for the purification of alberta tar sands waste waters

Thin film composite membranes of sulfonated poly(phenylene oxide) (SPPO)–polysulfone (PS) (SPPO–PS) were prepared by coating the hydrogen or sodium form of SPPO onto various porous substrates such as polysulfone (PS). The effects of membrane preparation conditions and feed water variables on the salt rejection and production rates were investigated using reverse osmosis. Purification of the waste waters from the Alberta heavy oil fields for desalination and recycling use was carried out. Production rates and salt rejections for the various feeds were found to be in the range of 5–20 gfd (gallons/ft² day) and 80–99% respectively at 600 psig and 20°C, depending on the experimental conditions and membrane properties.     

Improvement of performance of polyamide reverse osmosis membranes using dielectric barrier discharge plasma treatment as a novel surface modification method

In this research, surface modification of aromatic polyamide thin film composite (TFC) reverse osmosis (RO) membranes was carried out using dielectric barrier discharge (DBD) plasma treatment to improve the performance and fouling resistance of prepared RO membranes. First, polyamide TFC RO membranes were synthesized via interfacial polymerization of m‐phenylenediamine and trimesoyl chloride monomers over microporous polysulfone support membrane. Next, the DBD plasma treatment with 15 s, 30 s, 60 s, and 90 s duration was used for surface modification. The surface properties of RO membranes were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR), SEM, AFM, and contact angle measurements. The ATR‐FTIR results indicated that DBD plasma treatment caused hydrogen bonding on the surface of RO membranes. Also, the contact angle measurement showed that the hydrophilicity of the membranes was increased due to DBD plasma treatment. The changes in the membranes surface morphology indicated that the surface roughness of the membranes was increased after surface modification. In addition, it was found that the DBD plasma treatment increased the water permeation flux significantly and enhanced sodium chloride (NaCl) salt rejection slightly. Moreover, the filtration of bovine serum albumin revealed that the antifouling properties of the modified membranes had been improved. POLYM. ENG. SCI., 59:E468–E475, 2019. © 2018 Society of Plastics Engineers