Studies on Cellulose Acetate/Low Cyclic Dimmer Polysulfone Blend Ultrafiltration Membranes and their Applications

Abstract

Flat sheet ultrafiltration membranes from cellulose acetate (CA)/low cyclic dimer polysulfone (LCD PSf) were prepared by a phase inversion method. N, N′‐Dimethyl formamide and different molecular weight of polyethylene glycol (PEG 200, PEG 400, and PEG 600) were used as solvent and pore‐forming additive, respectively. The membranes were characterized in terms of pure water flux, water content, porosity, membrane hydraulic resistance, and morphology. The pure water flux was found to reach the highest value of 181.82 Lm^?2h^?1 at 5 wt.% PEG of 600 molecular weight and 10 wt.% LCD PSf content in the blended solution for membrane preparation. SEM micrographs indicated that the addition of PEG into the CA/LCD PSf solution changes the inner structure of the membrane. The influence of filtration time and applied pressure on membrane permeability was examined by copper/polyethylenimine complex rejection studies. With increase in filtration time, the rejection of the copper/polyethylenimine complex decreased and the results were discussed.     

Preparation and Characterization of Cellulose Acetate/Aminated Polysulfone Blend Ultrafiltration Membranes and their Application Studies

Abstract

Ultrafiltration membranes are largely being applied for heavy metal ion separations from aqueous streams. Cellulose acetate (CA) and aminated polysulfone (APSf) based membranes are prepared in the absence and presence of the polymeric additive, polyethylene glycol, PEG 600, in various compositions. The effects of polymer blend composition and additive concentration on compaction, pure water flux, membrane hydraulic resistance, water uptake, and contact angle has been investigated to evaluate the performance of the membranes and the results are discussed. Surface and cross-sectional morphologies of membranes were also analyzed using scanning electron microscopy. Toxic heavy metal ions such as Cu²⁺, Ni²⁺, Cd²⁺, and Zn²⁺ were separated by the blend membranes using polyethyleneimine (PEI) as polymeric ligand. The rejection and permeate flux efficiencies of the blend membranes are compared with pure cellulose acetate membranes.     

Comparative Study of Enantioseparation of Racemic Tryptophan by Ultrafiltration Using BSA-Immobilized and BSA-Interpenetrating Network Polysulfone Membranes

Effectiveness of Bovine Serum Albumin (BSA) as chiral recognizing protein in enantiomers separation by ultrafiltration technique was studied by immobilizing BSA on the membrane and incorporating BSA as semi-interpenetrating network in the membrane matrix. Separation of racemic tryptophan solution was performed in closed loop cross flow ultrafiltration using BSA immobilized polysulfone membrane and polysulfone membrane having BSA semi-IPN network. The volumetric flux (J_v), the solute flux (J_s), the separation factor (α), and the enantiomeric excess (%ee) of two types of membranes at different trans-membrane pressures and permeation times were determined. BSA semi-IPN membrane exhibits higher volumetric as well as solute fluxes compared to BSA immobilized membrane. Separation factor (α) to the order of 1.89 was achieved with BSA immobilized membrane after 8 h of ultrafiltration and in the same duration BSA-IPN membrane exhibited separation factor (α) to the order of 1.62. BSA immobilized membrane exhibits higher enantiomeric excess (30.8%) compared to BSA semi-IPN membrane (23.8%) after 8 hrs. BSA molecules available on membrane as immobilized or as semi-IPN under go complexion with tryptophan enantiomers differently. BSA immobilized membrane performed better separation and enantiomeric purity; however, the solute flux of the membrane decreases.     

聚砜类分离膜材料及其改性研究进展

讨论了一些常用的聚砜类分离膜材料的结构与性能,从共混、共聚和表面接枝改性等方面对聚砜类膜材料的改性进行了详细的阐述,对聚砜类膜材料的研究与应用前景进行了展望。     

Ultrafiltration of Myoglobin using Surface-Sulfonated Polysulfone Hollow Fiber

The usage of ionic polysulfone (PSF) hollow fiber for the ultrafiltration of protein was investigated. The surface of polysulfone hollow fiber was sulfonated through the Blanc chloromethylation reaction to become anionic. Characterization of the modified hollow fiber was performed including ion exchange titration, pure water permeation, and molecular sieving measurement. The performance of ultrafiltration of protein was evaluated using myoglobin at various pH values. The results show that the water contact angles and hydraulic resistance are markedly decreased, indicating that the surface-modified PSF hollow fibers are more hydrophilic. In addition, the retention of myoglobin depends on the pH of the solution. At a pH higher than the isoelectric point of myoglobin, both hollow fiber and the protein have the same charge sign, and both the flux of the solution and the retention are the highest. The sulfonated PSF hollow fiber may be used as a biomaterial for protein separation and purification.     

New Inorganic Ultrafiltration Membranes: Titania and Zirconia Membranes

Destabilization of colloidal solutions permits preparation of titania and zirconia ultrafiltration membranes. In this work, layer thickness, pore diameter as a function of sintering temperature, and water permeability are developed. These membranes have a very good chemical resistance and can be used in all pH ranges in ultrafiltration processes. A comparison between alumina, titania, and zirconia membranes is given.     

相转化法制备聚砜膜研究进展

系统概述了相转化法制备聚矾膜时聚矾含量、添加剂、凝固浴及铸膜液在空气中的蒸发时间对其结构和性能的影响。随着聚矾含量的增加,膜结构从疏松向致密转变;在铸膜液中添加适合的添加剂可制备适当结构和渗透性能的聚矾膜;在凝固浴中添加适量的溶剂,可有效抑制膜内大孔结构的形成;空气中蒸发时间的增大时,膜表面趋于疏松,当增加到一定程度后基本趋于稳定。还综述了相转化法制备聚矾膜时聚矾含量、添加剂、凝固浴及铸膜液在空气中的蒸发时间对其结构和性能的影响。     

Polysulfone Membranes. III. Performance Evaluation of Polyethersulfone—PVP Membranes

Abstract

The performance of membranes produced from casting solutions consisting of polyethersulfone (PES), poly-(N-vinyl-pyrrolidone) (PVP), and N-methyl-2-pyrrolidinone (NMP) were systematically studied. Zero-shear casting solution viscosities for these polymer solutions were determined as a function of PES and PVP concentrations. Ultrafiltration membranes were then cast using the phase inversion technique and characterized by separation experiments using polyethylene glycols of various molecular weights as test solutes. A pore flow model was fitted to the resulting separation data to provide estimates of the average pore radius and membrane porosity. These parameters were used to compare laboratory results for this membrane casting solution system with performance data for commercially available polyethersulfone membranes.     

Preparation and Properties of Ultrafiltration Ceramic Membranes

A technology for preparing ceramic ultrafiltration membranes with a ZrO₂-based selective layer and their pore and separating characteristics are determined. The potential use of these membranes for separation or fractionation of polyvinylpyrrolidone and purification of apple pectin is demonstrated.     

Ultrafiltration Membranes Prepared by Styrene-Grafted Polyvinylpyrrolidone

Abstract

The suitability of a new grafted copolymer for preparing ultrafiltration membranes was studied. The copolymer was obtained by radiochemical grafting of styrene onto polyvinylpyrrolidone. The membranes were prepared by the phase-inversion technique from N-methyl-2-pyrrolidone solutions. Influence of grafting degree and solutions concentration on the ultrafiltration performances were studied. It was demonstrated that for polystyrene grafting values close to 85% w/w and a copolymer solution concentration of 15% w/v, the membranes have a high permeate flux (more than 100 L·m^?2·h^?1) and a good separation factor (more than 95%) for aqueous dextran solutions. The mechanical resistance of the membranes was evaluated and their microscopic structure was examined by SEM.     

Retention of Biopolymers by Ultrafiltration Membranes

Separation of biopolymers is one of increasingly important applications of ultrafiltration (UF) membranes. The efficiency of separation is often evaluated through pilot experiments and seldom predicted. Available predictions focus on correlations between UF pore width and biopolymer hydrodynamic diameter, while overlooking key operational parameters including transmembrane pressure (TMP). The role of TMP in the retention of biopolymers is revealed, i.e., magnification of TMP leads to decreased retention of the particulates. No full retention of the biopolymers without a rigid outer shell has been observed. Pressure‐induced stretching of flexible biopolymers and expansion of membrane pores are the possible reasons of deteriorating selectivity. A division into flexible and rigid biopolymers provides a better prediction of membrane selectivity.     

电场强化制备荷电聚砜超滤膜及其性能

采用高压电场强化技术,结合相转化法制备荷电超滤膜.添加剂、溶剂与膜材料分别为聚乙烯吡咯烷酮(PVP K30)、N–甲基–2–吡咯烷酮(NMP)与聚砜(PSF),主要对膜分离性能受到高分子聚合物质量分数、凝固浴温度、电场强度等因素的影响进行了研究与分析.结果表明,高压电场强化不会改变膜的微观结构,但会影响膜的分离性能.实...     

相转化法制备聚砜类纳滤膜的研究现状

介绍了国内外用浸入沉淀相转化法制备聚砜类纳滤膜的研究现状,系统阐述了浸入沉淀相转化法制备聚砜类纳滤膜时,聚合物含量、溶剂、添加剂、凝固浴、预蒸发时间和辐照对其结构和性能的影响,通过对这些因素的调节,可以改变相分离时的热力学和动力学过程,控制膜皮层的厚度、致密性,改变膜截面的孔结构,对膜的水通量和分离性能产生影响。     

聚砜超滤膜表面辐照改性研究

实验以聚砜为膜材料,聚乙二醇（PEG）为添加剂,采用浸入沉淀相转化法制备聚砜平板超滤膜,然后对实验制备的聚砜膜进行紫外辐照改性,考察了辐照对聚砜膜结构和性能的影响,研究了膜辐照前后断裂强度的变化,通过表面接触角测定仪、红外分析仪（FTIR）、扫描电镜（SEM）、改性膜的水通量和截留性能等方法来表征膜辐照前后的结构和性能变化,聚砜超滤膜经紫外辐照改性取得了良好的效果。     

基于后磺化的萘磺酸型磺化聚砜质子交换膜的性能

以环氧氯丙烷（EPO）为试剂,通过烷基化反应在聚砜（PSF）主链引入环氧基团制备环氧化聚砜（OPSF）,紧接着OPSF与2萘酚6,8二磺酸钾（NSK）通过反应制备一种萘磺酸型侧链磺化聚砜（PSF-NS）,PSF-NS的化学结构用红外光谱（FTIR）和核磁氢谱（1H-NMR）进行充分表征。同时采用溶液浇注的方法制备相应的质子交换膜（PEM）,研究温度对PEM的性能包括离子交换容量、吸水率、溶胀率和质子传导率等的影响。结果表明,相比于一些主链型磺化芳香聚合物PEM,PSF-NS在高吸水率下保持很好的尺寸稳定性;随着温度的升高,PSF-NS膜的吸水率、溶胀率和质子传导率增大,其中PSF-NS-4（磺酸基团键合量为1.43 mmol/g）在25 ℃和85 ℃的吸水率分别是29.6 % 和43.1 %,相应的溶胀率是25.2 % 和 56.2 %,甲醇渗透率为16.8×10-7 cm2/s,甲醇渗透率低于Nafion115膜在相同条件下的性能。     

Ultrafiltration of Albumin-Ethanol Solutions on Mineral Membranes

Abstract

This paper investigates the ultrafiltration of albumin-ethanol solutions on ZrO₂ mineral membranes for the preparation of human albumin from plasma. The classical process consists of a preconcentration phase of a 20% ethanol-albumin 7.5 g/L solution to raise albumin concentration to 80 g/L, then a diafiltration to reduce ethanol concentration to less than 0.3 g/L, and a final concentration to adjust albumin concentration to its final value of 210 g/L. The potential advantages of mineral membranes relative to the polysulfone membranes presently used are a longer membrane life and higher permeate fluxes in the presence of ethanol. In addition, they lend themselves to the use of back flushing or pulsatile flows for reducing membrane fouling. Using 2.7 mm i.d. Carbosep membranes with a 10 kd cut-off and velocities of 7 m/s, permeate fluxes of 40 L/hμm² at 4[ddot]C were obtained with 50 g/L albumin, 20% ethanol solutions representative of the preconcentration phase, while 45 to 50 L/hμm² were obtained at albumin concentrations of 100 g/L without ethanol at 8[ddot]C, representative of the final concentration phase. These fluxes compare favorably with fluxes obtained previously in our laboratory with polysulfone membranes which were respectively of 22 and 40 L/hμm² for the same solutions. This study confirms the expectation of a smaller reduction in the presence of ethanol of the permeate flux for the mineral membranes while albumin concentration in the permeate remained generally under 0.4 g/L irrespective of retentate concentration. The superposition of pressure and flow pulsations on the filter inlet by a piston-in-cylinder system decreases concentration polarization and increases permeate flux by 50 to 60% as compared with steady flows under the same conditions.     

Ultrafiltration Carbon Membranes from Organic Sol-Gel Process

We present a simple approach for preparing mesoporous carbon membranes on macroporous fly-ash-based ceramic supports via sol-gel polymerization of resorcinol with formaldehyde. The support was dip-coated and dried at 45°C under ambient pressure without a special drying process. The mesoporous carbon membrane was obtained after carbonization under a nitrogen atmosphere. The coating–pyrolysis process only required one cycle. The graphitization degree increased with carbonization temperature, as shown by X-ray diffraction. However, Raman spectroscopy revealed that defects emerged at high carbonization temperature. Scanning electron microscopy clearly showed the mesoporous carbon layer and macroporous support, a uniform carbon layer with thickness less than 1 µm forming on the support. The obtained carbon membrane shows uniform pores and high mesopore volume. The flux of pure water through the mesoporous carbon membrane was as high as 167 L · m^?2 · h^?1 · bar^?1. The molecular weight cutoff of this membrane was found to be about 20,000 Da.     

溶胶-凝胶法制备磺化聚砜/二氧化钛超滤膜

采用改性之后的聚砜作为原材料,通过溶胶-凝胶法与二氧化钛进行有机/无机杂化,将不同质量分数的二氧化钛加入磺化聚砜中,经过一系列处理得到磺化聚砜与二氧化钛杂化膜.通过对膜进行水接触角、纯水通量、截留率、机械强度的测试,得出以下结论:当二氧化钛的质量分数在3%以下时,有助于提高复合膜的亲水性和机械强度,在没有影响膜的截留率的同时增加了膜的通量,使得膜具有很好的抗污染能力;随着二氧化钛的不断加入,粒子发生团聚现象,导致杂化膜的性能开始下降.     

负载纳米银磺化聚醚砜超滤膜的制备及其抗菌性

为了改善聚醚砜(PES)膜的抗污染性能,将PES磺化并制成超滤膜,然后将超滤膜浸渍在硝酸银溶液中,吸附Ag~+的超滤膜在维生素C的还原作用下将Ag负载在膜表面,制备了负载纳米银磺化超滤聚醚砜膜(SPES-Ag)。通过扫描电镜(SEM)、原子力显微镜(AFM)、X射线衍射(XRD)对SPES-Ag超滤膜进行了表征,并通过细胞吸附法进行了抗菌性测试。结果表明,纳米银的平均尺寸为120 nm,它的负载提高了超滤膜的抗菌性能,对大肠杆菌、假单胞菌和金黄色葡萄球菌的抗菌率分别达到了96.7%,98.3%,87.7%。此外,水通量和截留率的测试结果表明,SPES-Ag超滤膜的水通量为438.4 L/(m~2·h),对牛血清蛋白(BSA)的截留率达到94.3%。