单外皮层PES中空纤维气体分离膜制备的研究

以聚醚砜(PES)作膜材料,N-甲基吡咯烷酮(NMP)为溶剂,乙醇(Ethanol)作非溶剂,NMP-Water为芯液,获得PES/NMP/Ethanol铸膜液[m(PES)∶m(NMP)∶m(Ethanol)=35∶57∶8],采用相转化法制备了PES中空纤维气体分离不对称膜,研究了保存时间、硅橡胶种类、芯液浓度、芯液流量和凝胶温度等对PES中空纤维膜O2/N2渗透性能的影响。同时,分析了单外皮层PES中空纤维气体分离膜的结构,讨论了PES中空纤维气体分离膜的机械性能。当芯液组成的m(NMP)∶m(H2O)=86∶14和凝胶温度17℃时,涂3%硅橡胶A后的PES中空纤维气体分离膜气体分离性能如下:αO2/N2=6.68,JO2=2.26GPU,JN2=0.33GPU。     

中空纤维膜分离技术在氢回收中的应用

随着生产能力的逐步提高,合成氨系统排放的吹除气由间歇排放改为稳定排放。为了降低合成氨生产成本,采用中空纤维膜分离技术回收吹除气中的H2用于合成氨生产。装置投运后,氢回收率最高达95%,合成氨产量由16.1 t/h提高至16.7 t/h,经济效益显著。     

PVDF树脂的物性对中空纤维膜性能的影响

采用了不同特性粘度的PVDF树脂,通过非溶剂致相分离法(NIPS)制备了相应的PVDF中空纤维膜。通过力学性能、纯水通量、牛血清白蛋白(BSA)截留率等性能测试发现,不同特性粘度的PVDF树脂制备的中空纤维膜的性能差异较大。随着PVDF特性粘度的增加,PVDF中空纤维膜的拉伸强度及断裂伸长率逐渐增加,纯水通量逐渐降低,BSA截留率先降低后增加。通过扫描电镜(SEM)进一步发现,随着PVDF特性粘度的增加,PVDF树脂制备的中空纤维膜,其海绵层上的孔状结构逐渐减少且变小。     

气体分离用聚砜中空纤维膜的活化涂敷技术

主要探讨了一些表面活性剂对气体分离用聚砜中空纤维膜表面涂敷上的作用。结果表明 ,其中TO 80对提高H2 /N2 分离系数的效果最佳。     

添加剂和凝结剂温度对用无溶剂致相位分离法生产高性能PVDF/聚醚F127混合中空光纤膜的影响(英文)

Poly(vinylidene fluoride)(PVDF) has become one of the most popular materials for membrane prepara-tion via nonsolvent induced phase separation(NIPS) process.In this study,an amphiphilic block copolymer,Plu-ronic F127,has been used as both a pore-former and a surface-modifier in the fabrication of PVDF hollow fiber membranes to enhance the membrane permeability and hydrophilicity.The effects of 2nd additive and coagulant temperature on the formation of PVDF/Pluronic F127 membranes have also been investigated.The as-spun hollow fibers were characterized in terms of cross-sectional morphology,pure water permeation(PWP),relative molecular mass cut-off(MWCO),membrane chemistry,and hydrophilicity.It was observed that the addition of Pluronic F127 significantly increased the PWP of as-spun fibers,while the membrane contact angle was reduced.However,the size of macrovoids in the membranes was undesirably large.The addition of a 2nd additive,including lithium chlo-ride(LiCl) and water,or an increase in coagulant temperature was found to effectively suppress the macrovoid for-mation in the Pluronic-containing membranes.In addition,the use of LiCl as a 2nd additive also further enhanced the PWP and hydrophilicity of the membranes,while the surface pore size became smaller.PVDF hollow fiber with a PWP as high as 2530 L?m?2?h?1?MPa?1,a MWCO of 53000 and a contact angle of 71° was successfully fabricated with 3%(by mass) of Pluronic F127 and 3%(by mass) of LiCl at a coagulant temperature of 25 °C,which shows better performance as compared with most of PVDF hollow fiber membranes made by NIPS method.     

聚偏氟乙烯中空纤维膜的开发与应用进展

介绍了中空纤维膜的性能,生产的主要技术工艺与最佳的操作条件及有关进展情况。阐述了国内外研究开发的现状与发展趋势,并探讨了扩大应用范围等的前景与市场需求。     

中空纤维膜的研究现状与发展

本文综述了中空纤维膜近年来国内外在反渗透、超滤、微滤及气体分离方面的开发应用现状。重点介绍了在渗透汽化、膜萃取、膜蒸馏等过程中的最新研究状况，并提出了对发展中空纤维膜的几点看法。     

中空纤维膜吸收烟气二氧化硫

本文综述了国内外用膜吸收法治理烟气二氧化硫的研究现状,对采用中空纤维膜吸收过程中的膜组件操作方式、吸收剂、膜材料以及工艺参数的选择进行了介绍,并应用双膜理论对中空纤维膜吸收二氧化硫过程中的各分传质系数和总传质系数进行了推导,初步探讨了建立膜吸收过程数学模型的方法。     

Improved Desalination Performance of Polyvinylidene Fluoride Hollow Fiber Membranes by the Intermediate Role of Surfactants

Polymer hollow fiber membranes (HFMs) are the core or base membranes of various membrane processes (e.g., ultrafiltration and membrane distillation). Preparing polymer HFMs with higher water flux helps improve the efficiency of the membrane processes. Using pore-forming additives is the commonly used and efficient method to improve the water flux. The current dilemma is that the conventional methods that increase the amounts or the molecular weight of the additives to improve the water flux usually lead to the decrease in membrane mechanical strength. Herein, different from the conventional research strategy, increasing the surfactant surface activity (SA) is first found to deeply promote the core of nonsolvent-induced phase separation (NIPS) that of the mutual diffusion between water and dopes. As a result, this method distinctly improves the surface porosity (from 0.8% to 9.7%) and optimizes the pore size distribution of polyvinylidene fluoride (PVDF) HFMs. Benefit from these, the water flux of ultrafiltration (3.1-fold increase, maximally) and direct contact membrane distillation (2.3-fold increase, maximally) are increased greatly. Moreover, the mechanical strength is not negatively affected due to the additive amount of small molecule surfactants is constant and small (2.0 wt%).     

Hollow Fiber Ultrafiltration Membranes from Poly(Vinyl Chloride): Preparation,Morphologies, and Properties

Hollow fiber poly(vinyl chloride) membranes were prepared by using the dry/wet spinning method. Cross-section, internal, and external surfaces of the hollow fibers structure were studied by SEM. The pore size and pore size distribution of the hollow fibers were measured by a PMI capillary flow porometer. UF experiments of pure water and aqueous solution of PVP K-90 were carried out. The effect of the PVC concentration on the hollow fibers mechanical properties was also investigated. It was found that the PVC fibers cross-sectional structure was affected by the polymer concentration in the dope solution. In particular, reduction of macrovoids size was observed when increasing PVC concentration from 15 to 19 wt%. The pore size distribution of the PVC hollow fibers was controlled by adjusting the PVC concentration. Indeed, an increase of PVC concentration up to 19 wt% leads to fibers with sharp pore size distribution (the 99% of pores is about 0.15 µm).The pure water permeation flux decreased from 162 to 128 (l/m² · h · bar), while the solute separation performance increased from 82 to 97.5%, when increasing the PVC concentration. The elongation at break, the tensile strength, and the Young's modulus of the PVC hollow fibers were improved with PVC concentration in dope solution.     

An Explicit Solution for Concentration Polarization for Gas Separation in a Hollow Fiber Membrane

In the present work, a one-dimensional mathematical model is developed to analyze the concentration polarization phenomenon for the separation of gas mixtures in composite hollow fiber membranes. An analytical expression is developed for determining the interfacial concentration at the interface of dense and porous support layers. Further, the model accounts for the non-ideality of the gas mixture. Both co-current and counter-current flow configurations for the separation of hydrogen from a three-component mixture are studied. The effects of feed side pressure and velocity as well as permeability on concentration polarization are probed. It is apparent from this study that the concentration polarization phenomenon significantly affects the separation efficiency at higher permeability values.     

分子印迹纤维膜富集分离白藜芦醇的研究

以白藜芦醇为模板分予,聚偏氟乙烯中空纤维膜为支撑体,采用自由基热聚合法制各自藜芦醇分子印迹复合膜,对膜分离性能进行了测试。结果表明,当萃取剂为纯甲醇时,物质透过膜的魁很少,印迹膜体现出对模板分子的吸附选择性;当萃取剂为0．3％冰醋酸．甲醇时,印迹膜呈现对模板分子的透过选择性。     

Separation of Phenol from Aqueous Streams by a Composite Hollow Fiber Based Pervaporation Process Using Polydimethyl siloxane (PDMS)/Polyether-Block-Amide (PEBA) as Two-Layer Membranes

Abstract

In order to simultaneously achieve both high permselectivity and permeability (flux) for the recovery of aromatic compounds such as phenol from aqueous streams, a composite organophilic hollow fiber based pervaporation process using PDMS/PEBA as two-layer membranes has been developed. The process employed a hydrophobic microporous polypropylene hollow fiber, having thin layers of silicones (PDMS) and PEBA polymers coating on the inside diameter. The composite membrane module is used to investigate the pervaporation behavior of phenol in water in a separate study; and that of a mixture of phenol, methanol, and formaldehyde in an aqueous stream (a typical constituent of wastewater stream of phenol-formaldehyde resin manufacturing process) in another study. The fluxes of phenol and water increase relatively linearly with increasing concentration especially at low feed concentration, and exhibit a near plateau with further increase in concentration. As a result, the phenol/water separation factor decreases as the feed concentration increases. Significant improvement in phenol/water separation factor and phenol flux is achieved for this two-layer (PDMS/PEBA) membranes as compared to that achieved using only PDMS membrane. The phenol and water fluxes and the separation factor are highly sensitive to permeate pressure as all decrease sharply with increase in permeate pressure. For this membrane, an increase in temperature increases the separation factor, and also permeation fluxes of phenol and water. An increase in feed-solution velocity does not have a significant effect on phenol and water fluxes, and also on the separation factor at least within the range of the feed-solution velocity considered. In the study of pervaporation behavior of a typical constituent of wastewater stream of phenol-formaldehyde resin manufacturing process, phenol permeation shows a much higher flux and a higher increase in flux with increase in concentration is also exhibited as compared to that exhibited by methanol permeation. This thus indicates that the membrane is more permeable to phenol than to methanol and formaldehyde.     

中空纤维超滤膜去除乳酸钙中蛋白质的研究

发酵法联合生产乳酸-乳酸钙工艺中,分离出的乳酸钙产品含有蛋白质、还原糖、重金属等杂质,影响产品的品质。本实验研究了中空纤维膜对乳酸钙中蛋白质的去除,并分析了压差、温度、浓度及pH值等因素的影响。得到了较好的工艺操作条件为Δp=0.05MPa,Δ=30g/L,30°C,pH=4。进一步提出用多步超滤能提高蛋白质的去除率15%～27%。     

Improving Blood Compatibility of Polyethersulfone Hollow Fiber Membranes via Blending with Sulfonated Polyether Ether Ketone

Appropriate membrane for blood contacting applications requires hemocompatibility and high permeation flux; it should inhibit proteins or platelets adsorption and still possess high permeability. Aiming to improve the polyethersulfone (PES) hollow fiber membrane hemocompatibility, sulfonated polyether ether ketone (SPEEK) is self‐synthesized in the present research and added to PES in different ratios. Scanning electron microscopy images have revealed significant changes in PES membranes structure after addition of SPEEK, which can influence water permeation property of the membranes. Water contact angles of the membranes have reduced from 75° to 50° after addition of 4 wt% SPEEK. Influence of SPEEK addition on hemocompatibility of the PES membranes is evaluated via protein (bovine serum albumin) adsorption, platelet attachment, and coagulation time (APTT and TT) assays. Obtained results reveal that hemocompatibility of the modified hollow fiber membranes is enhanced as a result of emerging repulsive forces between negative charges on the membranes surface and negatively charge blood components.

     

离子液体-中空纤维支撑液膜技术分离Cs／Mo研究

支撑液膜（SLM）发展迅速、应用前景广阔,在众多支撑液膜性能改进的研究中,采用离子液体（IL）代替传统有机溶剂,已在气体、有机物分离以及生物反应器方面有一定的进展。本实验采用疏水性聚丙烯中空纤维（HF）作支撑体,针对目标金属Cs离子选择杯冠化合物DB18C6作萃取剂,预选[Bmim][PR]、[Bmim][NTf2]和[Bmim][BF4]三种ILs作稀释剂制备膜体系,探索其在Cs／Mo分离中的应用潜力。结果表明,在本实验工艺条件下,使用[Bmim][PF6]成功制备了离子液体中空纤维支撑液膜体系（IL—HFSLM）,该液膜体系在料液流速低于5mL／min的条件下稳定存在,并可实现从含Mo溶液中回收超过80％的Cs。     

Removal of Volatile Organic Compounds from Water by Pervaporation Using Polyetherimide-Polyethersulfone Blend Hollow Fiber Membranes

Abstract

Removal of volatile organic compounds (VOCs) such as 1,2-dichloroethane, trichloroethylene, chlorobenzene and toluene from water solutions through polyetherimide (PEI)-polyethersulfone (PES) blend hollow fiber membranes was investigated by pervaporation (PV) in this work. The separation performances of the membranes were researched by varying the spinning conditions (such as coagulation temperature and air gap distance) for the preparation of the hollow fibers and the operation conditions (such as velocity, concentration, and temperature of feed liquids). For the PEI-PES blend hollow fiber membrane prepared when the air gap was 7 cm and the temperature of coagulation bath was 45°C, it possessed high selectivity to the aqueous solutions containing 0.04 wt.% of VOCs at 20°C. The separation factors to 1,2-dichloroethane, trichloroethylene, chlorobenzene and toluene were 7069, 5759, 3952, and 3205, respectively. It was found that the pervaporation performance of the blend hollow fiber membrane was strongly related to the molecular size of the VOCs. The order of the selectivities was 1,2-dichloroethane > trichloroethylene > chlorobenzene > toluene.     

中空纤维膜制备方法研究进展

介绍了中空纤维膜3种主要制备方法,即溶液纺丝法、熔融纺丝-拉仲法和热致相分离法。分别阐述了这3种方法的技术路线和致孔机理,回顾了3者的进展,展望了中空纤维膜制备技术的发展趋势。     

Improvement of H2/CH4 Separation Performance of PES Hollow Fiber Membranes by Addition of MWCNTs into Polymeric Matrix

Carboxylated multiwalled carbon nanotubes (MWCNTs) were added to polyethersulfone hollow fiber membranes to improve their H₂/CH₄ separation properties. The addition of MWCNTs up to 1 wt% increased macrovoids formation in cross-section, while in 2 wt% loading, decreased due to increase in dope viscosity. The best gas separation performance for the mixed-matrix hollow fiber membranes was achieved at 1 wt% MWCNTs loading with hydrogen permeance of 69 GPU and H₂/CH₄ selectivity of 44.1 at 5 bar(g). Tensile test results showed that incorporation of MWCNTs into the polymeric matrix affected the mechanical properties of the fabricated membranes.