静电纺丝纳米纤维膜固定化酶及其应用*

静电纺丝是一种简单有效的制备聚合物纳米纤维的技术,在组织工程、药物控释和传感器等方面具有广泛的应用。采用静电纺丝技术制备得到的纳米纤维膜具有比表面积大、孔隙率高和易于分离回收等优点,可以作为一种优良的酶固定化载体,目前在酶固定化领域受到了广泛的关注。本文综述了近年来静电纺丝纳米纤维膜固定化酶的研究进展,在阐述静电纺丝纳米纤维膜制备技术的基础上,详细介绍了纳米纤维膜表面担载法和包埋法固定化酶的原理和方法,分析了不同固定化方法的优缺点,并讨论了静电纺丝纳米纤维膜固定化酶的应用前景,对静电纺丝纳米纤维膜固定化酶的发展方向进行了展望。     

聚全氟乙丙烯中空纤维膜的制备及性能

以聚全氟乙丙烯(FEP)为成膜聚合物,MT-Ⅱ型复合粉为致孔剂,邻苯二甲酸二辛酯(DOP)为稀释剂,采用熔融纺丝拉伸法制备了FEP中空纤维膜,研究了其耐酸碱等性能.结果表明,FEP中空纤维膜的表面具有由拉伸孔、界面孔及溶出孔组成的多重孔结构,而其横截面为均匀分布的海绵状孔结构.FEP中空纤维膜经质量分数为25%的硫酸水溶液和25%的氢氧化钠水溶液分别处理60 d后,膜的化学结构未发生变化,而且平均孔径增大,孔径分布变窄,断裂强度保持率分别在86.8%及80.8%以上,耐酸碱性明显优于商业化聚偏氟乙烯(PVDF)中空纤维膜,显示出优异的化学稳定性及良好的热稳定性.     

聚酰亚胺纤维

聚酰亚胺纤维具有高强度模、耐高温、耐辐射等优越的性能。在多种纺制聚酰亚胺纤维的方法中,湿纺容易制得高强高模的样品。本文主要介绍了聚酰亚胺纤维的一步法湿纺、二步法湿纺和熔融纺丝方法,并对纤维的性能进行了概述。     

聚4-甲基-1-戊烯膜的制备与应用研究进展

聚4-甲基-1-戊烯是一种具有低密度、高透气性等优良性质的膜材料,具有广泛的应用前景.本文从制备方法和具体应用两个方面综述了近年来国内外PMP膜的研究进展,重点介绍了热致相分离法、熔融拉伸法、溶剂挥发法及静电纺丝法、非溶剂致相分离法、热致相分离-熔融拉伸耦合法等其它方法进行PMP膜制备的原理及影响因素,并对PMP膜在体...     

静电纺丝技术制备聚合物基中空结构材料

静电纺丝是一种制备纳米尺度连续长丝的技术, 采用静电纺丝技术高效可控地构筑微纳米中空结构材料备受关注. 本文综述了通过静电纺丝技术制备聚合物中空纤维和中空微球的研究进展, 展望了其在不同功能材料领域的发展前景.     

静电纺丝中空纳米纤维在催化领域的应用

更大的比表面积、更丰富的界面组成及更高效的传质路径是构筑多元催化体系,实现催化剂效率提升的关键.中空纳米纤维具有的多元空腔结构赋予其比表面积和界面组成上广阔的调变空间,使其成为制备高效异相催化剂的理想平台.静电纺丝技术的发展为中空纳米纤维的可控制备提供了更简易高效的方法,促进了中空纳米纤维的结构创新和应用扩展.本文从构筑策略、结构特点及结构与性能的对应关系3个角度总结了基于静电纺丝法制备的不同组成和形态的中空纳米纤维材料在催化领域(包括光催化、电催化、热催化)应用中的独特优势.首先展示了创新的静电纺丝方法结合后续工艺制备的中空纳米纤维的不同结构形态,然后梳理了基于中空纳米纤维构筑高效催化剂的研究进展,最后展望了中空纳米纤维在催化领域应用的未来发展趋势,以期为高效异相催化剂的设计提供有益的参考.     

熔融纺丝-拉伸法制备PVDF中空纤维膜及其油-水分离性能

以聚偏氟乙烯(PVDF)为成膜聚合物, 聚全氟乙丙烯(FEP)为添加剂, 聚乙二醇(PEG)和氯化钙(CaCl₂)为复合成孔剂, 采用熔融纺丝-拉伸法制备了PVDF中空纤维膜. 在制膜过程中未使用其它溶剂和稀释剂, 实现了制膜过程的相对绿色化. 分析和讨论了拉伸比对PVDF中空纤维膜结构与性能的影响, 测试了纤维膜的孔径分布、 力学性能和油-水分离性能等. 结果表明, 进行拉伸后处理的膜的孔径分布较窄, 在油包水乳液分离测试中, 分离效率均在97%以上, 表现出良好的油-水分离效果.     

简易熔融纺丝实验装置

合成纤维是三大合成高分子材料之一,它的加工过程主要是成纤过程即纺丝.纤维纺丝的最基本和应用最广泛的方法有熔融纺丝法和溶液纺丝法,其中的熔融纺丝法较为常用,速度快,操作简便.     

静电纺丝法制备新型吸附分离材料

随着现代经济、工业的发展,许多环境问题出现在了人类面前,对于新型吸附分离材料的需求也变得十分迫切。静电纺丝法是一种简单有效制备连续纳米长丝的技术,有着十分广阔的应用前景。由于静电纺丝法制备的纤维膜具有较大的比表面积、易于调控的微观结构及化学性质,静电纺丝法能够用于制备新型的吸附分离材料。本文对电纺纤维膜的制备与改性,以及电纺纤维膜在空气过滤、油水分离、重金属离子去除等领域的应用进行了介绍,同时对其未来的发展进行了展望。     

静电纺丝法制备丹皮酚纤维膜的综合实验设计

设计了静电纺丝法制备以聚己内酯为载体的含丹皮酚的载药纤维膜的综合实验,实验涉及载药纤维膜的制备和表征测试等操作。采用静电纺丝技术制备了丹皮酚纤维膜,利用红外光谱仪,扫描电镜和X-射线衍射仪进行了表征。通过此综合教学实验,学生可了解纳米纤维膜的制备方法及表征技术,掌握红外光谱仪的原理及操作技术,了解扫描电镜、X射线衍射仪等大型仪器的原理和制样方法。该实验项目涵盖多个知识点,综合性强,便于操作,可作为高分子材料与工程、制药工程等本科专业的综合实验项目,培养学生的综合实验技能和创新能力,激发他们对科研的兴趣。     

聚全氟乙丙烯中空纤维膜研究

以聚全氟乙丙烯(FEP)为成膜聚合物,复合无机粒子为成孔剂,邻苯二甲酸二辛酯(DOP)为稀释剂,采用熔融纺丝工艺制备得到FEP中空纤维膜.分析和讨论了不同成膜体系对FEP中空纤维膜热性能、动态力学性能和力学性能的影响,并对膜的纯水通量和孔径分布进行表征.用扫描电子显微镜(SEM)观察了膜的横断面和表面形貌.结果表明,所得FEP中空纤维膜为由溶出微孔和界面微孔组成的海绵状孔结构.随着成孔剂含量的增加,成孔剂在成膜体系中分散程度变差,容易发生团聚,最终导致膜孔径变大,孔径分布变宽.成孔剂和稀释剂对FEP中空纤维膜的热性能和动态力学性能影响较小.当FEP含量增加到70 wt％时,膜表面容易形成一层致密层,降低了膜的通透性.     

Self-assembly of inner skin hollow fiber polyelectrolyte multilayer membranes by a dynamic negative pressure layer-by-layer technique

In the past studies, electrostatic layer-by-layer (LbL) adsorption of oppositely charged polyelectrolytes has proven to be a promising method for the preparation of polyelectrolyte multilayer membranes (PEMMs). Till now, this method was mainly used to assemble flat sheet and tubular membranes. Since hollow fiber membrane has some advantages such as high-packing density, self-contained mechanical support and hence the consequent economical superiority, this study therefore seeked to assemble inner skin hollow fiber PEMMs by using a dynamic LbL adsorption technique. The assembly process was successfully accomplished by alternatively dynamically filtrating polyacrylic acid (PAA) and polyethyleneimine (PEI) on a hydrolyzed hollow fiber polyacrylonitrile (PAN) membrane under a negative pressure condition. In the case of pervaporation separation of 95 wt.% ethanol–water mixture (50 °C), the membrane obtained with only 4.5 and 6.5 bilayers had separation factor of 245 and 1338 while the permeate fluxes were 290 and 120 g/(m² h), respectively. The pervaporation separation behavior of various alcohol/water mixtures with the alcohols being t-butanol, 2-propanol and ethanol were also investigated. Finally, scanning electron microscopy and atomic force microscopy clearly confirms a uniform and defect-free layer formed on the inner surface of hollow fiber support. Since different polyelectrolyte pairs could be used to assemble PEMMs for different uses, it was expected that the dynamic negative pressure LbL adsorption technique could also potentially be used to prepare many types of PEMMs in other fields.     

中空纤维复合膜

中空纤维复合膜是分离膜的一种,它是由两种(或两种以上)不同的材料采用一定的制备工艺复合而成的,其优点是将中空纤维的结构特点(如自支撑等)和复合膜的分离优势(如高选择性高通量等)有机结合.本文首先介绍了中空纤维复合膜的基膜及复合层所用到的材料(或添加材料),并按照中空纤维复合膜的结构特点对其进行了简单的分类,并重点论述了中空纤维复合膜的制备设备及工艺.最后论述了中空纤维复合膜在渗透汽化、气体分离和纳滤等领域的研究进展和应用情况,指出中空纤维复合膜需要继续深入的研究内容.     

On-line coupling of high performance gel filtration chromatography with imaged capillary isoelectric focusing using a membrane interface

A high performance liquid chromatography system, a sample preparation device, and an imaged capillary IEF (CIEF) instrument are integrated and multiplexed on-line. The system is equivalent to two-dimensional polyacrylamide gel electrophoresis (2-D PAGE), by transferring the principle of 2-D separation to the capillary format. High performance liquid chromatography (HPLC) provides protein separation based on size using a gel filtration chromatography (GFC) column. Each eluted protein is sampled and directed to a novel microdialysis hollow fiber membrane device, where simultaneous desalting and carrier ampholyte mixing occurs. The sample is then driven to the separation column in an on-line fashion, where CIEF takes place. The fluidic technology used by our 2-D system leads to natural automation. The coupling of the two techniques is simple. This is attributed to high speed and efficiency of the sample preparation device that acts as an interface between the two systems, as well as the speed and simplicity of our whole column absorption imaged CIEF instrument. To demonstrate the feasibility of this approach, the separation of a mixture of two model proteins is studied. Sample preparation and CIEF were complete in just 4-5 min, for each of the eluted proteins. Total analysis time is about 24 min. Three-dimensional data representations are constructed. Challenges and methods to further improve our instrument are discussed, and the design of an improved horseshoe-shaped sample preparation sample loop membrane interface is presented and characterized.     

COMSOL软件在枸杞多糖超滤膜生物反应器中膜阻塞模型构建中的应用

基于聚砜中空纤维超滤膜分离技术精制枸杞多糖（Lycium barbarum polysaccharide）,通过COMSOL软件对枸杞多糖膜阻塞逆流提取及超声设备参数进行修正,获得更优的纯化工艺。采用微波-超声法提取枸杞多糖,并利用聚砜中空纤维超滤膜对枸杞多糖进行分离,采用单因素分析及正交实验考察枸杞多糖提取和分离过程中的重要参数,通过COMSOL软件对重要膜阻塞参数进行修正。结果表明,枸杞多糖提取较优工艺条件为：提取温度50~70 ℃之间,超声功率50 W,固液比例1∶8~1∶12（mg∶mL）,提取时间40~60 min;当超滤膜截留相对分子质量为1×10⁴时,膜通量较好;正交实验结果表明,膜通量与料液温度关系最大,其次是膜pH值和分离操作压;COMSOL软件对枸杞多糖连续逆流提取设备进行仿真计算,结果发现与全封闭叶片相比,开孔叶片能够显著降低溶剂短路现象,使得最低流速提升高达65倍。基于COMSOL软件数据修订,枸杞多糖分离效率得到大幅度提升,为枸杞多糖工业化生产提供必要的数据积累。     

Racemic ofloxacin separation by supported-liquid membrane extraction with two organic phases

As the relation of chirality and activities of drugs is researched deeply, people become to re-alize the clinic importance of chirality. The different enantiomers of a drug can have vastly differ-ent pharmacological activities, pharmacokinetic processes and toxicity[1,2]. The most well-docu- mented example is that of the drug substance thalidomide. Bitter lessons and scientific research promote the interest in single-enantiomer drugs, so the potential of the chiral drug market is enormous[3]. …     

High-affinity sulfonated materials with transition metal counterions for enhanced protein separation in dual-layer hollow fiber membrane chromatography

High-affinity membrane materials have been successfully synthesized through a combination of the polymer sulfonation reaction with transition metal counterion exchange treatment. This type of promising materials were embodied for the first time with the aid of dual-layer hollow fiber technology for protein separation. Three types of immobilized metal affinity membranes (Cu(2+), Ni(2+) and Zn(2+) forms) were developed in this work and they all exhibited enhanced protein separation performance compared to the as-spun hollow fiber in H(+) form due to the strong affinity between transition metal counterions and target protein molecules. Ultimately, the high-purity target protein (>99%, w/w) could be achieved via the membrane in Cu(2+) form.     

A review on the latest development of carbon membranes for gas separation

Inorganic membranes have been developed before 1945. The earlier application of inorganic membranes was primarily concentrate on military purpose. Carbon membrane is one type of porous inorganic membrane. Although the concept of carbon membrane for gas separation has been found in the early 1970, the interest to develop carbon membrane only increased, since Koresh and Soffer successfully prepared apparently crack-free molecular sieving hollow fiber carbon membranes. Nowadays, plenty of researchers have used different polymeric materials; including polyimides, to prepare carbon membranes by using pyrolysis. In general, carbon membranes can be divided into four major configurations: flat sheet, membrane supported on tube, capillary, and hollow fiber. Permeation properties of carbon membranes have been improved greatly in these 20 years. Carbon membranes offer advantages over polymeric membranes especially in terms of selectivity as well as thermal and chemical stability. More attention will be paid to carbon membranes in this century. This paper will review the development of carbon membranes in the last 30 years and give a clear future direction in research for carbon membrane.     

PREPARATION OF ASYMMETRIC POLYETHERKETONE FLAT AND HOLLOW FIBER MEMBRANES FOR GAS SEPARATION USING ACETIC ACID BASED COAGULANTS

Membranes for gas separation have developed significantly in the last twenty years,however,there is still a need for high temperature and chemically resistant membranes that exhibit good selectivity and gas permeability.Our study examines the fundamental properties of polyetherketone (PEK,a thermally stable and chemically resistant polymer) membranes prepared using concentrated sulphuric acid (98% H_2SO_4) as the solvent.Non-solvents used in the work included acetic acid,ethanol,methanol,glycerol,and wat...     

Preparation of composite hollow fiber membranes: co-extrusion of hydrophilic coatings onto porous hydrophobic support structures

Coating a layer onto a support membrane can serve as a means of surface functionalization of membranes. Frequently, this procedure is a two-step process. In this paper, we describe a concept of membrane preparation in which a coating layer forms in situ onto a support membrane in one step by a co-extrusion process. Our aim is to apply a thin ion exchange layer (sulfonated polyethersulfone, SPES) onto a polysulfone support. The mechanical stability and adhesion of the ion-exchange material to the hydrophobic support membrane (polysulfone) has been studied by a systematic approach of initial proof-of-principle experiments, followed by single layer and double-layer flat sheet casting. Critical parameters quantified by the latter experiments are translated into the co-extrusion spinning process. The composite hollow fiber membrane has low flux as a supported liquid membrane for the copper removal due to the low ion exchange capacity of the SPES. The coating layer of the composite membrane is porous as indicated by gas pair selectivity close to unity. However, our new composite membrane has good nanofiltration properties: it passes mono and bivalent inorganic salts but rejects larger charged organic molecules. The experimental work demonstrates that co-extrusion can be a viable process to continuously prepare surface tailored hollow fiber membranes in a one-step process, even if the support and coating material differ significantly in hydrophilicity.