中空纤维渗透汽化复合膜及组件研究进展

中空纤维渗透汽化膜组件具有器件小型化及成本较低等方面的优势,其工业应用潜力巨大。本文介绍了中空纤维渗透汽化复合膜及组件的研究进展,阐述了膜材料、成膜方法以及组件结构参数等对组件渗透汽化性能的影响,并对中空纤维渗透汽化膜组件的中试研究进行了总结。通过组件放大及中试研究发现,中空纤维渗透汽化膜组件的装填密度、长度以及抽吸方式均会影响其下游侧的真空度,从而影响其渗透汽化性能。膜材料的分子设计、组件的结构参数优化以及耐溶剂耐高温封装将是中空纤维渗透汽化膜组件未来工业放大过程中的关键环节。     

Characterization of sodium alginate and poly(vinyl alcohol) blend membranes in pervaporation separation

By blending a rigid polymer, sodium alginate (SA), and a flexible polymer, poly(vinyl alcohol) (PVA), SA/PVA blend membranes were prepared for the pervaporation separation of ethanol–water mixtures. The rigid SA membrane showed a serious decline in flux and a increase in separation factor due to the relaxation of polymeric chains, whereas the flexible PVA membrane kept consistent membrane performance during pervaporation. Compared with the nascent SA membrane, all of the blend membranes prepared could have an enhanced membrane mobility by which the relaxation during pervaporation operation could be reduced. From the pervaporation separation of the ethanol–water mixtures along with the temperature range of 50–80°C, the effects of operating temperature and PVA content in membrane were investigated on membrane performance, as well as the extent of the relaxation. The morphology of the blend membrane was observed with PVA content by a scanning electron microscopy. The relaxational phenomena during pervaporation were also elucidated through an analysis on experimental data of membrane performance measured by repeating the operation in the given temperature range. SA/PVA blend membrane with 10 wt % of PVA content was crosslinked with glutaraldehyde to enhance membrane stability in water, and the result of pervaporation separation of an ethanol–water mixture through the membrane was discussed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:949–959, 1998     

Potentials of pervaporation to assist VOCs’ recovery by liquid absorption

Gas treatment by liquid absorption is a well-known process to remove volatile organic compounds (VOCs) from industrial waste gases. Usually the liquid is an organic solvent of high boiling point; however, after VOCs’ absorption it must be regenerated for the possible reuse and this step is classically achieved by heating the liquid. The paper presents the work directed to investigate an alternative regeneration step based on a liquid-vapour membrane separation, i.e. pervaporation. Because most of the energy required in pervaporation processes is consumed to remove the minor component from the initial mixture by selective permeation through the membrane, one can expect a significant energy cut in the operational costs linked to the regeneration of the liquid if the pervaporation step can substitute the heating one. The results reported here show that the technological possibility to use pervaporation is first governed by the stability of the membrane in the absorption liquid. The viability of the overall process is actually controlled by the mutual affinity between the VOCs, the solvent phase and the polymeric material. As a matter of fact, whereas VOCs have to exhibit strong affinities to both the solvent and the membrane material, the polymer has to be well resistant and even repellent to the solvent to avoid the possible sorption in the membrane that would drastically depress the pervaporation efficiency. In other words the membrane transport properties must be specific for the VOCs. This goal was reached following several experimental approaches, going from membrane modifications to the selection of suitable heavy protic solvents. Hence it has been shown for the case of dichloromethane (DCM) that low molecular weights polyalcohols (e.g. glycols) appeared to be suitable media to allow in particular the specific transport of DCM. On the other hand, polydimethylsiloxane (PDMS) based membranes were selected for their stability in these polyglycols and for their marked affinity for DCM. The simulation of the hybrid gas treatment process at pilot-scale was also achieved by a simple model relying on experimental data for both vapour liquid equilibria and permeation flux. A simple comparison of the energy needed to regenerate the heavy solvent by each possible step has also been made.     

Liquid phase desulfurization of jet fuel by a combined pervaporation and adsorption process

Since the conventional hydrodesulfurization process employed in the refinery industry is not suitable for mobile fuel cell applications (e.g. auxiliary power units, APUs), the present study aims at developing an alternative process and determining its technical feasibility. A large number of processes were assessed with respect to their application in fuel cell APUs. The results revealed that a two-step process combining pervaporation and adsorption is a suitable process for the on-board desulfurization of jet fuel. Therefore, a pervaporation process with subsequent adsorption was selected for detailed investigation. Six different membrane materials and ten sorbent materials were screened to choose the most suitable candidates. Further laboratory experiments were conducted to optimize the operating conditions and to collect data for a pilot plant design. Different jet fuel qualities with up to 1675 ppmw of sulfur can be desulfurized to a level of 10 ppmw. The aim of developing a suitable process for the desulfurization of jet fuel in fuel cell APUs was thus achieved.     

渗透汽化膜的制备及其应用进展

渗透汽化（pervaportion, PV）作为一种新颖的分离技术在工业范围内得以应用,至关重要的是它在恒沸混合物、近沸混合物分离方面的显著优势。相比分馏、精馏、萃取等传统分离方法,渗透汽化技术具有经济、高效、便于管理的优点,但目前缺少优质的渗透汽化膜材料和先进的膜制备方法。本文综述了近年来渗透汽化技术以及渗透汽化膜的研究现状,首先介绍了PV技术的分离机理、PV膜的制备方法、PV技术在工业上的应用领域等,并重点讨论了料液温度、料液浓度、料液流速、膜上下游蒸汽压差、膜材料等关键因素对渗透汽化分离性能的影响。文中提出未来渗透汽化技术应在膜材料方面积极探索,选用聚合物为材料,并结合先进的膜制备方法来进一步降低膜的厚度,从而明显地提高膜渗透通量。     

渗透蒸发分离醋酸/水体系

介绍渗透蒸发分离醋酸/水体系的研究现状及应用前景,对目前分离醋酸/水体系的透酸膜和透水膜的性能进行较全面的归纳,阐述渗透蒸发分离醋酸/水过程的理论研究状况及存在的问题.指出膜的制备是当前首要的研究课题之一,必须开发新的膜材料并对现有膜材料进行改性;溶解-扩散理论存在相当的局限性,引入量子化学理论和分子动力学理论将对渗透蒸发过程的模拟研究产生推动作用.     

Pervaporation separation of alcohol–water mixture through 4-vinylpyridine chemical modified poly(4-methyl-1-pentene) membrane

For dehydrating separation aqueous alcohol solution by the pervaporation technique, a chemical modified poly(4-methyl-1-pentene) (TPX) membrane was synthesized with 4-vinylpyridine (4-VP). The morphology, crystallinity, and thermodegradation properties were investigated by scanning electron microscopy, X-ray, and thermogravimetric analysis, respectively. The modified TPX membrane possessed higher stability than that of the unmodified TPX membrane. The effects of feed temperature and poly(4-VP) (P4-VP) content of the modified TPX membranes on the performances of pervaporation were studied. A separation factor of 133 and a permeation rate of 115 g/mh can be obtained for the TPX/P4-VP membrane with 3.0 wt % P4-VP content. © 1995 John Wiley & Sons, Inc.     

ZSM-5沸石填充聚氨酯膜的制备及渗透汽化分离水中乙酸异丙酯

采用两步法制备了ZSM-5沸石填充的疏水性端羟基聚丁二烯基聚氨酯（PU）膜,用以分离水中芳香性有机物乙酸异丙酯。对该膜的化学结构、形貌及热稳定性进行了表征,并研究了ZSM-5沸石填充的PU膜的溶胀度及渗透汽化性能。结果表明：添加ZSM-5沸石后,膜的热稳定性明显提高,沸石与膜的相容性较好,且随着添加量的增加,膜的溶胀度降低,分离因子先升后降。在303 K、料液浓质量分数为1%的条件下,ZSM-5添加量为20%（质量分数）时,分离因子达到最高;同时随着料液浓度及操作温度的上升,通量和分离因子都增加。在333 K、料液质量分数为1%的条件下,PU-ZSM-5-20膜的分离因子及通量最高可达288.72 g/（m2·h）和53.21 g/（m2·h）。     

Permeation and separation of aqueous alcohol solutions through grafted poly(vinyl alcohol) latex membranes

The poly(vinyl alcohol)–acrylonitrile–2-hydroxy ethyl methacrylate (PVA–AN–HEMA) grafted latex membrane was synthesized by grafting AN and HEMA mixture on PVA in aqueous solution. The ceric ammonium nitric in nitric acid was was used as a catalyst. This membrane has well-balanced composition of hydrophilic and hydrophobic components and was proved by transition electron microscopy to process microstructure between continuous and disperse phases. The permeability of alcohol–water solution and separativity of phenol–water solution through this PVA–AN–HEMA membrane were studied. It was found that the permeation rate for aqueous solution as as alcohol–water was greater than that for pure water, and the separativity of phenol–water solution by pervaporation increased as the amount of PHEMA increased.     

水溶液中挥发性有机化合物渗透蒸发分离技术

介绍了水溶液中挥发性有机化合物 (VOCs)的各种分离方法 ,重点分析了渗透蒸发分离技术经济优势。阐释了渗透蒸发膜的选择标准、渗透蒸发过程的传质机理 ,以及原料液浓度、原料液温度、原料液流量、渗透侧压力、添加剂和膜组件型式等因素对渗透蒸发过程分离效率的影响 ,并简要预测了渗透蒸发过程的发展趋势与动态。     

Effect of polystyrene stars with fullerene C60 cores on pervaporation properties of poly(phenylene oxide) membrane

Star‐shaped macromolecules with six arms of polystyrene grafted onto a fullerene C₆₀ core, or fullerene‐containing polystyrene (FPS), were used for the modification of poly(phenylene oxide) (PPO) and the preparation of a dense thin‐film membrane. The membrane structure was studied using scanning electron microscopy. The effect of FPS modifier on membrane density and mass transfer of methanol and ethylene glycol through the membrane was studied. Sorption and pervaporation tests were used to determine degree of sorption, diffusion coefficients, flux through the membrane and separation factor. In the pervaporation of a methanol–ethylene glycol mixture over the concentration range of 10–30 wt% methanol in the feed, all membranes showed high affinity to methanol. The separation factor reached a maximum at 5 wt% FPS in the membrane. The PPO/FPS membranes exhibit the best separation properties when the feed is enriched with ethylene glycol. © 2016 Society of Chemical Industry     

PDMS/ZSM-5膜的制备及渗透汽化分离水中乙酸正丁酯和乙酸乙酯

为探究出适合分离水中的乙酸正丁酯和乙酸乙酯的新型渗透汽化膜材料,选用沸石ZSM-5 对聚二甲基硅氧烷(PDMS)材料进行填充改性,以聚偏氟乙烯(PVDF)为支撑层,采用刮涂法制备PDMS/ZSM-5/PVDF复合膜渗透汽化分离水中的乙酸正丁酯和乙酸乙酯。采用SEM、接触角测量仪、FTIR、TGA和XRD等对膜材料物理化学性能进行表征,考察了膜材料的溶胀行为及渗透汽化性能。结果表明,ZSM-5在 PDMS 膜中分散均匀,且没有发生化学作用,并提高了膜材料的疏水性和热稳定性。随着ZSM-5添加量的增加,膜在乙酸正丁酯和乙酸乙酯的溶胀度和待分离组分在膜材料中的扩散速率不断增加。随着进料浓度和温度的增加,渗透通量不断增大,分离因子先增大后减小。随着ZSM-5在PDMS/ZSM-5/PVDF复合膜中含量的增加,总渗透通量增加,而分离因子呈现先增加后减小的趋势。当添加量为10%（质量）时,分离因子达到最大值。对于乙酸正丁酯/水体系,渗透通量和分离因子最大值分别为319 g·m ^-2·h ^-1和131;而对于乙酸乙酯/水体系,渗透通量和分离因子最大值分别为1385 g·m ^-2·h ^-1和121。     

渗透蒸发分离水—乙醇研究──Ⅰ．乙醇水溶液与多元反应体系分离特征

以聚酰胺羧酸为膜材料，考察了制膜条件、化学改性对膜亲水性及水－乙醇分离性能的影响；针对戊酸与乙醇的酯化反应，测定了改性膜对多元反应体系的分性能，并初步分析了膜分离过程对酯化反应的影响。     

渗透蒸发复合膜的选材与制备

与对称膜、非对称膜相比,渗透蒸发复合膜有扩散阻力小、渗透通量高、机械强度好等优点,同时在选材和制备方面也有其自身的特点。活性层材料主要依据Flory huggins相互作用参数理论或溶解度参数理论进行粗略选择,再通过一些实验手段做进一步筛选。支撑层材料多为无机或有机多孔材料,选择的主要依据是材料的物理化学性质、机械性质及结构。另外,活性层与支撑层之间的黏合与孔渗也是必须考虑的问题。介绍了相关的黏合理论,列举了常用的防止孔渗发生的措施。最后结合近年来渗透蒸发复合膜的研究实例详细介绍了复合膜的常用制备方法,如界面聚合法、浸涂法、等离子聚合法和自组装法等。     

Ultrasound Assisted Pervaporation Separation of Pyridine/Water Mixtures Using Poly(vinyl alcohol)/Polyacrylonitrile Blend Membranes

Poly(vinyl alcohol)/polyacrylonitrile blend membranes were prepared to separate pyridine/water mixtures by pervaporation. The membranes were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The effects of membrane composition, feed pyridine concentration, operating temperature, downstream pressure and ultrasound irradiation on the separation process were evaluated. The experimental results indicated that with increasing PVA mass ratio and operating temperature the permeate flux increased but the separation factor decreased, while with increasing feed concentration and downstream pressure the separation factor increased and the permeate flux decreased. It was observed that Ultrasound irradiation enhanced the permeate flux.     

Structure and Performance of Poly(vinyl alcohol)/Poly(γ-benzyl L-glutamate) Blend Membranes

Poly(vinyl alcohol) (PVA)/poly(γ-benzyl L-glutamate) (PBLG) blend membranes with different PBLG wt contents were prepared by pervaporation. Structure and surface morphologies of PVA/PBLG blend membranes were investigated by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Thermal, mechanical, and chemical properties of PVA/PBLG blend membrane were studied by differential scanning calorimeter (DSC), tensile strength tests, and other physical methods. It was revealed that the introduction of PBLG homopolymer into PVA could exert an outstanding effect on the properties of PVA membrane.     

聚氨酯渗透蒸发膜的研究进展

综述了聚氨酯渗透蒸发膜在渗透蒸发分离中的研究进展,分析了聚氨酯膜软硬段结构及其它因素对其分离性能的影响,并对聚氨酯膜的改性方法进行总结和评述。指出了聚氨酯膜目前研究中存在的不足及发展趋势。     

Studies on the state of permeant in the membrane and its effect on pervaporation phenomena

Pervaporation experiments of pure water and 2-propanol through poly-dimethylsiloxane membranes were carried out in order to study the effect of the interaction between permeant and membrane material on pervaporation phenomena. From the effect of downstream pressure on the pervaporation rate, the saturation vapor pressure of water in the membrane was determined to be 2.799 × 10³ Pa (21.0 mmHg), which is the same as the literature value, whereas that of 2-propanol in the membrane was estimated to be 5.865 × 10³ Pa (44.0 mm Hg), which is 8.53 × 10² Pa (6.4 mmHg) higher than that of pure 2-propanol. In the differential scanning calorimetry analyses of permeants in the membrane, it was evident that the state of 2-propanol in the polydimethylsiloxane membrane was different from that of bulk 2-propanol. On the other hand, the state of water in the membrane was assigned to that of bulk water. Throughout the present study, it was observed that the interaction between permeant and membrane material plays an important role in determining pervaporation phenomena.     

A study on the effect of cross-linkers on pervaporation performance of room temperature vulcanised silicone rubber membranes for butanol recovery

As a rising membrane separation technology, pervaporation (PV) has been regarded as one of the most promising separation technology applied in separation of azeotropic mixtures due to its high selectivity and low energy consumption. In a PV process, separation process mainly occurs in the PV membrane, so it is of significance to develop a membrane with high performance. Room temperature vulcanised (RTV) silicone rubber is a kind of membrane material possessing good hydrophobicity and low glass transition temperature. It is widely used in the recovery of organic compounds from their dilute aqueous solutions. In this paper, RTV silicone rubber membranes were fabricated by a typical one-pot method and characterised by Fourier transform infrared spectroscopy, thermal gravimetric analysis, water contacting angle, differential scanning calorimetry, scanning electron microscopy and swelling experiment. The membranes were used in PV recovery of n-butanol from its dilute aqueous solution (about 1?wt-%). The influences of temperature and cross-linkers on the performance of PV were discussed at the same time. In conclusion, RTV silicone rubber membrane cross-linked by vinyltrimethoxysilane (WD-21), which obtained membrane selectivity of 82.9 with butanol permeability of 1.1_?×_?10⁶ Barrer at 50°C, got the best performance.     

Preparation and characterization of PVA-g-GO/PVA/PAN composite membrane for pervaporation desalination

Graphene oxide (GO) has extensive applications in membrane-based separations, but its dispersion in the membrane has always been a problem due to the presence of π–π interactions in GO nanosheets. In this study, a grafting reaction was designed by using poly (vinyl alcohol) (PVA) for GO grafting modification and poly (vinyl alcohol)-g-graphene oxide (PVA-g-GO) nanocomposites were synthesized. The grafting material to GO was the same as the basic separation polymer material. PVA-g-GO showed better dispersibility and hydrophilicity than GO, and a series of composite membranes were prepared using a polyacrylonitrile (PAN) ultrafiltration (UF) membrane as a substrate. PVA-g-GO nanocomposites and membranes were characterized by using X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), water contact angle, scanning electron microscopy (SEM), etc. The addition of PVA-g-GO improved both the separation performance and anti-swelling property of the composite membrane, and the PVA-g-GO/PVA/PAN composite membrane loaded with 2 wt.% PVA-g-GO obtained a high flux of 4.46 kg/m² · h and a high rejection of 99.99% when dehydrating 3.5 wt.% NaCl solution at 30°C by pervaporation.