Effect of Isomeric Propanols on the Performances of Polyethersulfone Nanofiltration Membranes

Abstract

In this work, polyethersulfone (PES) asymmetric nanofiltration (NF) membranes were prepared by immersion precipitation phase inversion process. The casting solution contained N-methyl-2-pyrrolidone (NMP) as solvent, 1-propanol and 2-propanol as nonsolvent additives, and polyvinylpyrrolidone (PVP) as pore former additive. Water was used as a coagulant. The effects of the PVP content in the casting solution and the exposed time on the performances of the NF membranes were investigated. It was found that with the increase of PVP content, the pure water flux (PWF) increased to the largest value and then decreased. The rejection to PEG 1000 always decreased. The largest value (1281.40 kg · m^?2 · h^?1 · MPa^?1) of PWF appeared when the content of 1-propanol was 9 wt.%. However, when 2-propanol was added in the casting solution, the largest value of PWF was only 678.37 kg · m^?2 · h^?1 · MPa^?1 (the content of 2-propanol was 7 wt.% and other preparing conditions were unchanged). The results meant that both PWF and rejection of the membranes with 1-propanol as additive were higher than that of 2-propanol as additive. The possible reason was discussed from the viewpoint of the difference of solubility of propanols to PES and PVP.     

磺化聚醚砜质子交换膜的制备及性能研究

以浓硫酸为溶剂、氯磺酸为磺化剂对聚醚砜（PES）进行了磺化，采用氢核磁共振谱（^1H NMR）、傅立叶变换红外光谱（FTIR）及热重分析（TGA）对磺化聚醚砜（SPES）进行了表征，证实PES得到了磺化。制备了一系列不同磺化度的SPES膜，测试了膜的接触角、含水率和电导率。试验结果表明，SPES具有良好的热稳定性；随着磺化度的增加，膜的亲水性能增加，膜的电导率增加。当SPES膜的磺化度达到37．0％（摩尔分数）时，SPES膜在室温下的电导率与商业化的Nafion 112膜的电导率相当。     

溶剂/非溶剂体系对聚醚砜微孔膜性能和结构的影响

以N,N-二甲基乙酰胺(DMAc)、N-甲基吡咯烷酮(NMP)和N,N-二甲基甲酰胺(DMF)为溶剂,乙醇(EtOH)、异丙醇(IPA)、正丁醇(BuOH)、一缩二乙二醇(DegOH)、聚乙二醇400(PEG400)为非溶剂添加剂,研究了溶剂/非溶剂体系对聚醚砜(PES)膜的结构和性能的影响.改变铸膜液体系中的非溶剂含量对膜的结构和性能有很大影响,但是这种影响不是以非溶剂的绝对含量来衡量的,而取决于非溶剂/溶剂的比值.改变溶剂的组成和配比也改变了溶剂/非溶剂体系,体系的溶度参数越接近PES的溶度参数,与PES的相容性越好,但是膜的通量较小.实验结果表明,采用NMP(或DMAc)与DMF以适当比例混合作溶剂,比采用单一NMP(或DMAc)作为溶剂制得的膜通量要大.通过改变溶剂配比,可实现对膜的表面开孔率、孔径、断面结构等参数的微控.     

Characteristics and Performances of Blended Polyethersulfone and Carbon-Based Nanomaterial Membranes: Effect of Nanomaterial Types and Air Exposure

Polyethersulfone (PES) is a widely used polymeric material for ultrafiltration or nanofiltration membranes. To enhance membrane permeability, rejection, and antifouling performance, the effect of four different types of carbon-based nanomaterials and air exposures during PES/carbon-based nanomaterial membrane fabrication was evaluated. The carbon-based nanomaterials were pristine carbon nanotubes, oxidized CNTs (CNTs-O), pristine graphene nanoplatelets (GNPs-P), and oxidized graphene nanoplatelets (GNPs-O). The characteristics and performances of pure and blended membranes were investigated based on their permeability, porosity, morphology, and hydrophobicity. Longer air contact time during membrane preparation resulted in lower membrane permeability, hydrophobicity, and porosity. All fabricated membranes tended to have channelled sponge-like structure, and highest permeability was attributed to the PES/GNPs-O membrane.     

PET沉析纤维表面形貌及热性能研究

通过纤维形态分析仪、扫描电镜、X射线衍射仪和热重分析仪对聚对苯二甲酸乙二醇酯(PET)沉析纤维的尺寸大小、表面形貌、结晶性能和热学特性四个方面进行检测分析。结果表明:PET沉析纤维相比市售PET浆粕纤维长度较短,细小纤维含量占70.4%;PET沉析纤维表面分丝帚化现象明显,其外形呈飘带状,形态柔顺,比表面积高达8.009 9 m~2/g;相比浆粕纤维,PET沉析纤维的结晶度和热稳定性相对较高,结晶度为37.88%,初始分解温度365℃,最大分解速率对应的温度为438℃,表明PET沉析纤维具有优异的热学特性,可广泛用于湿法成纸及复合材料增强等领域。     

聚醚砜超滤膜的制备与优化

为了给复合膜制备提供理想的支撑基膜,采用L-S相转化法制备聚醚砜超滤膜。通过正交实验设计,系统研究了各种因素对聚醚砜超滤膜性能的影响,并采用回归分析得到了模型方程。结果表明:所制备的聚醚砜超滤膜的水通量为246. 9L·m-2·h-1 (操作压力0. 1MPa),该膜对浓度为500mg/L的聚乙烯醇(PVA80 000)截留率达95%以上。     

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.

     

聚醚砜质量分数对聚偏氟乙烯/聚醚砜共混膜性能和结构的影响

用与聚醚砜共混的方法来改善聚偏氟乙烯膜的抗收缩性能,以二甲基乙酰胺作溶剂,聚乙烯吡咯烷酮为添加剂,研究了聚醚砜(PES)质量分数对聚偏氟乙烯/聚醚砜共混膜的收缩率、水通量、截留率及形态结构的影响。聚醚砜的加入可以有效地降低共混膜的收缩率,在w(PES)=1.5%时,共混膜的水通量取得极大值,截留率取得极小值。     

PMMA/PEG共混物形态和热性质的研究

在聚乙二醇存在的情况下,自由基聚合得到的聚甲基丙烯酸甲酯/聚乙二醇(PMMA/PEG)共混物,是一种半结晶聚合物;有相分离发生,一部分PEG晶体依然保持其晶体的特征,另一部分PEG晶体转变成非晶态,与PMMA网络复合,形成完全均一的非晶相。     

Preparation and Characterization of Poly(Acrylonitrile-co-Maleic Anhydride) Copolymer Modified Polyethersulfone Membranes

In this study, modified polyethersulfone (PES) membrane with pH sensitivity and heavy metal ion adsorption was prepared by blending a copolymer of poly(acrylonitrile-co-maleic anhydride) (P(AN-MA)). The copolymer was synthesized by free radical reaction using deionized water as the solvent, and was characterized by Fourier transform infrared spectroscopy (FTIR) analysis, elemental analysis, and gel permeation chromatography technique (GPC) measurement. Scanning electron microscopy (SEM) was used to investigate the morphology of the membrane. The modified PES membranes showed excellent pH sensitivity and pH reversibility. Furthermore, the modified PES membrane had the ability to absorb Ag⁺, Cu²⁺, Fe²⁺, and Fe³⁺. In addition, three simplified kinetic models (pseudo-first-order, pseudo-second-order, and intraparticle diffusion model) and adsorption isotherms (Langmuir and Freundlich) were used for the analysis of Cu²⁺ adsorption.     

聚醚砜改性及生物相容性研究

以聚醚砜(PES)、聚醚聚氨酯(PEU)及临床应用较广泛的亲水性抗凝血材料GAMBRO作为对比,对肝素化聚醚砜材料(H-PES)的血液相容性进行了研究。用全自动生化分析仪分别测定了血液与材料作用时血液中的血小板、凝血因子、白细胞及红细胞,采用分光光度计对材料表面溶血率进行了研究,比较了不同材料的复钙时间。实验结果表明,H-PES血小板吸附量仅为17×109/L,复钙时间约7min,引起Ca2+消耗也较少,仅有0.1mmol/L,但对白细胞吸附不理想。除PES以外,其余材料的溶血率都在5%以下。     

MFI型沸石膜的渗透分离性能及应用

综述了ＭＦＩ型沸石分子筛的渗透分离性能,探讨了其可能的分离机理,并介绍了包括膜分离与经在内的前沿进展。     

PE-HD／PA66原位复合材料的制备、形态与性能

用挤出-拉伸-注塑法制备了不含和含马来酸酐接枝聚乙烯(PE-MAH)的PE-HD/PA66原位复合(ISC)材料，以不拉伸的普通共混材料作对照，研究了PA66质量份数(fw)和引入PE-MAH(用量为0.2fw)对材料相形态、拉伸强度(σt)及模量(E)的影响及其作用机理，证明这种ISC材料能取得可观的增强效果：fw=15％条件下，不增容和增容材料的σ1分别比纯PE-HD提高45％和50％，E提高40％和25％，而相应增容普通共混材料的σt和E仅比纯PE-H13提高不到20％和30％。     

Morphology and Thermal Characteristics of Polyamide/Monosodium Glutamate Membranes

The membranes were prepared with various concentrations of polyamide and monosodium glutamate additive for dialysis application in this work. The membranes were characterized by determining creatinine diffusive permeability and by obtaining scanning electron microscope images and thermal characteristics. The results show that a membrane prepared without additive has a thick skin layer and a nonporous sublayer. The permeation of creatinine solute does not take place due to this dense (thick/nonporous) structure. When an additive is used in membrane synthesis, the thickness of skin layer reduces and voids are present, which results in permeation of this unwanted solute through the membrane.     

聚醚砜中空纤维血浆分离膜的孔径大小及分布

本文采用场致扫描电镜的显微观察法和膜对溶质的粒子筛分法测定聚醚砜中空纤维血浆分离膜的孔径大小及分布。通过显微镜观察统计得到膜的几何平均孔径为229nm,膜孔孔径分布在150nm,-350nm,筛分法测试得到膜的平均孔径为197nm。平均孔径大小约为200nm的聚醚砜中空纤维膜适合做血浆分离膜。     

PEG含量对PVDF/PEG共混膜性能的影响

以聚乙二醇(PEG)为添加剂,利用非溶剂致相分离法制备了聚偏氟乙烯(PVDF)/PEG共混膜,使用傅里叶变换红外光谱、X射线衍射、扫描电子显微镜、接触角测量等表征测试方法,研究了PEG含量对PVDF/PEG共混膜性能的影响。结果发现,PEG的加入使PVDF的结晶性能下降,同时也使其结构发生了变化。但是由于PEG的亲水性,当PEG的质量分数小于5%时,PVDF/PEG共混膜的亲水性随着PEG含量的增大而逐渐得到改善。     

Preparation and Characterization of pH-Sensitive Polyethersulfone Membranes Blended with Poly(methyl methacrylate-co-maleic anhydride) Copolymer

The current study aims to endow polyethersulfone (PES) hollow fiber membranes (HFMs) with improved pH-sensitivity by blending a random copolymer of poly(methyl methacrylate-co-maleic anhydride) (P(MMA-MA)). It was found that PES membrane modified by random copolymer had more obvious pH-sensitivity than those by alternative copolymer; while low molecular weight copolymer modified PES membrane had no pH-sensitivity. P(MMA-MA) was synthesized by a controlled dosing method via free radical polymerization and characterized by Fourier transform infrared spectroscopy (FTIR) analysis, nuclear magnetic resonance (¹H NMR), elemental analysis, gel permeation chromatography technique (GPC), and differential scanning calorimetry (DSC) measurement. Scanning electron microscopy (SEM) was used to investigate the morphology of the HFMs. The modified HFMs showed excellent pH-sensitivity, pH-reversibility and hysteresis of water flux. Through the ultrafiltration of PEG solution, we investigated the pore size change and the electroviscous effect on the water flux of the modified HFMs. Meanwhile, the modified membranes were stable with respect to the mechanical force (pressure) and exhibited good ability of Cu²⁺ adsorption.     

Effect of Casting Solution on Morphology and Performance of PVDF Microfiltration Membranes

The effects of preparation‐influencing parameters such as polymer concentration, thickness of casting solution, and type of solvent on morphology and performance of poly(vinylidene difluoride) (PVDF) microfiltration membranes for the treatment of emulsified oily wastewater were investigated. Flat‐sheet membranes were prepared from a casting solution of polymer and additive in various solvents by immersing the prepared films in nonsolvent‐containing mixtures of water and 2‐propanol. The membranes were characterized using scanning electron microscopy. Increasing the polymer concentration and membrane thickness significantly affected the pore size, leading to permeate flux decrease. An attempt was made to correlate the effect of the solvent on membrane morphology and performance employing solubility parameters between solvent and nonsolvent).     

凝固浴组成对NMMO法纤维素膜形貌的影响

为实现对分离用纤维素膜形貌的控制,采用NMMO法,分别以水、甲醇、乙醇和由它们配制的双组分溶液为凝固浴,制备了纤维素膜,观察了干膜的表面和断面形貌,测定了湿膜的孔结构参数,在对比基础上分析了干膜中微孔的形成过程与机制,探讨了纤维素结晶尺度与湿膜平均孔径的相关性和影响因素.研究表明,不同凝固浴制备出的纤维素膜在干态形貌上差别明显.纤维素膜的湿态孔隙率基本不受凝固浴组成影响,而干态下的致密区域在水溶胀后呈现多孔结构,对湿膜平均孔径影响很大.通过改变凝固浴组成,可分别或协同地调控纤维素膜的干态或湿态结构.     

聚偏氟乙烯微孔膜的制备与透过性能研究

采用相转化法制备聚偏氟乙烯（PVDF）微孔膜,研究了铸膜液中聚偏氟乙烯含量、溶剂的种类、添加剂的种类和含量、膜厚度以及操作压力等因素对聚偏氟乙烯膜水通量的影响,采用扫描电子显微镜观测了制备膜的表面结构。结果表明,制膜条件对聚偏氟乙烯微孔膜通量有重要影响,通量随添加剂含量和压力的增大而增大,随PVDF含量和膜厚度的增大而减小;当压力上升到0．16MPa时,通量将不随压力变化,达到极限通量。