Spray coating of polysulfone/poly(ethylene glycol) block polymer on macroporous substrates followed by selective swelling for composite ultrafiltration membranes

Polysulfone(PSF) is extensively used for the production of ultrafiltration(UF) membranes thanks to its high strength,chemical stability,and good processibility.However,PSF is intrinsically hydrophobic,and hydrophilic modification is always required to PSF-based membranes if they are intended to be used in aqueous systems.Facile strategies to prepare hydrophilic PSF membranes are thus highly demanded.Herein we spray coat a PSF-based amphiphilic block polymer onto macroporous substrates followed by selective swelling to prepare flat-sheet PSF UF membranes.The polymer is a triblock polymer containing PSF as the majority middle block tethered with shorter block of polyethylene glycol(PEG) on both ends,that is,PEG-b-PSF-b-PEG.We use the technique of spray coa ting to homogeneously dispense diluted triblock polymer solutions on the top of macroporous supports,instantly resulting in uniform,defect-free polymer coating layers with the thickness down to ~1.2 μm.The bi-layered composite structures are then immerged in ethanol/acetone mixture to generate mesoscale pores in the coating layers following the mechanism of selective swelling-induced pore generation,thus producing composite membranes with the mesoporous triblock polymer coating as the selective layers.This facile strategy is free from additional hydrophilic modification and much smaller dosages of polymers are used compared to conventional casting methods.The pore sizes,porositie s,hydrophilicity,and consequently the separation properties of the membranes can be flexibly tuned by changing the swelling duration and the composition of the swelling bath.This strategy combining spray coating and selective swelling is upscalable for the production of highperformance PSF UF membranes.

Preparation of antifouling ultrafiltration membranes from copolymers of polysulfone and zwitterionic poly(arylene ether sulfone)s

The past few decades have witnessed rapid gains in our demands of antifouling membranes such as water purification membranes and hemodialysis membranes.A variety of methodologies have been proposed for improving the antifouling performance and the hemocompatibility of the membranes.In this study,a series of copolymers(PSF-PESSB)containing polysulfone(PSF)and poly(arylene ether sulfone)bearing pendant zwitterionic sulfobetaine groups(PESSB)were prepared via one-pot polycondensation.Subsequently,the ultrafiltration(UF)membranes were prepared from different zwitterion-containing copolymers.The prepared membranes showed high thermal stability and mechanical properties.Besides,it also displayed attractive antifouling performance and blood compatibility.Compared with the original PSF membrane,the amount of protein absorption on the modified membrane was reduced;the flux recovery ratio and the resistance to blood cells were significantly improved.The results of this work suggest that PSF-PESSB membranes are expected to be applied in blood purification.The introduction of zwitterion-containing polymers to membranes paves ways for developing advanced hemodialysis technologies for crucial process.

Characterization of polysulfone hollow-fiber ultrafiltration membrane and its cleaning efficiency by streaming potential and flux method

Polysulfone(PS)hollow-fiber ultrafiltration membrane was characterized combined with flux and streaming potential in single electrolyte solutions.The effects of trans-membrane pressure,electrolyte concentration,ion valence and pH value of electrolyte solution on the streaming potential(SP)of the membrane were investigated.The zeta potential and surface charge density of the membrane were calculated on the basis of Helmholtz-Smoluchowski equation and Gouy-Chapmann theory.The results indicate that the valence and concentration of cation have a greater influence on the SP and surface charge density of PS membrane than those of anion,and the pH value of electrolyte solution has great effects on the SP and zeta potential of the membrane surface. Both the absolute value of the streaming potential and water flux of the adsorbed membrane decrease,compared with those of the clean membrane.The streaming potential and flux of the cleaned membrane can be completely recovered by cleaning with the mass fraction of 0.8%EDTA at pH=10.

Selective swelling of polysulfone/poly(ethylene glycol) block copolymer towards fouling-resistant ultrafiltration membranes

Fouling resistance of ultrafiltration(UF) membranes is critical for their long-term usages in terms of stable performance, so convenient approaches to prepare fouling-resistant membranes are always anticipated. Herein, we demonstrate the facile fabrication of antifouling polysulfone-block-poly(ethylene glycol)(PSF-b-PEG, SFEG)composite membranes. SFEG layer was coated onto macroporous supports and cavitated by immerging them in acetone/n-propanol following the mechanism of selective swelling induced pore generation. Thus-produced SFEG membranes possessed high permeance and excellent mechanical strength. Meanwhile, the structures and separation performances of the SFEG layers can be continuously tuned through simply changing swelling durations. More importantly, the hydrophilic PEG chains were spontaneously enriched onto the pore walls through swelling treatment, endowing intrinsic antifouling property to the SFEG membranes. Bovine serum albumin(BSA)/humic acid(HA) fouling tests proved the prominent fouling resistance of SFEG membranes, and the fouling resistance is expected to be long-standing because of the firm connection between PEG chains and PSF matrix by covalent bonding.

Modification Effect of Nano-Graphene Oxide on Properties and Structure of Polysulfone Ultrafiltration Membrane

In order to improve the purification properties of polysulfone (PSF) ultrafiltration membranes (UFM), nano-graphene oxide (nano-GO) was taken as modifier, and the physical blending process was adopted in our experiment. The microstructure, surface morphology and functional groups of modified UFM have been characterized respectively by scanning electron microscopy, atomic force microscopy and Fourier transform infrared spectroscopy, and the static contact angle between the membrane surface and the water droplet has also been detected to show the change of its hydrophilicity. Through experiments, it has been found that modified UFM has larger and more developed finger micro-pores, and there exist a large number of -OH groups on its surface, and also its hydrophilicity has been enhanced. The result of the experiments show that the modified UFM may keep rejection above 97% and its water flux can be reached at about 219.1 L/(m2·h) under pressure of 1 bar if 0.4 wt% of nano-GO was added. Additionally, the nano-GO can increase the flux recovery radio (FRR) of the membranes, and the maximum FRR was observed as 74.4% if 0.3 wt% of nano-GO was appended.

Uncovering the effect of poly(ethylene-co-vinyl alcohol)molecular weight and vinyl alcohol content on morphology,antifouling,and permeation properties of polysulfone ultrafiltration membrane:thermodynamic and formation hydrodynamic behavior

Various hydrophilic poly(ethylene-co-vinyl alcohol)(EVOH)were used herein to precisely control the structure and hydrodynamic properties of polysulfone(PSF)membranes.Particularly,to prepare pristine PSF and PSF/EVOH blends with increasing vinyl alcohol(VOH:73%,68%,56%),the non-solvent-induced phase separation(NIPS)technique was used.Polyethylene glycol was used as a compatibilizer and as a porogen in N,Ndimethylacetamide.Rheological and ultrasonic separation kinetic measurements were also carried out to develop an ultrafiltration membrane mechanism.The extracted membrane properties and filtration capabilities were systematically compared to the proposed mechanism.Accordingly,the addition of EVOH led to an increase in the rheology of the dopes.The resulting membranes exhibited a microporous structure,while the finger-like structures became more evident with increasing VOH content.The PSF/EVOH behavior was changed from immediate to delayed segregation due to a change in the hydrodynamic kinetics.Interestingly,the PSF/EVOH32 membranes showed high hydrophilicity and achieved a pure water permeability of 264 L·m^(–2)·h^(–1)·bar^(–1),which was higher than that of pure PSF membranes(171 L·m^(–2)·h^(–1)·bar^(–1)).In addition,PSF/EVOH32 rejected bovine serum albumin at a high rate(>90%)and achieved a significant restoration of permeability.Finally,from the thermodynamic and hydrodynamic results,valuable insights into the selection of hydrophilic copolymers were provided to tailor the membrane structure while improving both the permeability and antifouling performance.

Synthesis and Preparation of Polysulfone Hollow Fiber Chelating Membrane Modified with Thiourea

Several kinds of chloromethyl polysulfones （CMPF） with different chlorinity and reactive groups were synthesized by Friedel.crafts reaction, which could be utilized as reactively matrix membrane materials. The CMPF hollow matrix membranes were prepared with phase inversion by utilization of CMPF/additive/DMAC casting solution and CMPF as membrane materials. It was found that the effects of additive content, bore liquid and dry spinning distance on the structure of CMPF hollow fiber matrix membrane were different. A high qualified palysulfone hollow fiber chelating membrane modified with thiourea as chelating groups was prepared using CMPF as membrane matrix materials, through the reaction between thiourea and CMPF hollow fiber matrix membrane to afford the methyl iso-thiourium polysulfone. The experimental results showed that thermal drawing could increase the mechanical properties of matrix membrane, and the thermal treatment could increase the homogeneity and stability of the structure of polysulfoue hollow fiber chelating membrane modified with thiourea.

基于氨基酸MOF的共混超滤膜制备及性能研究

亲水化改性是解决聚砜(PSf)膜污染问题的重要策略之一,而将PSf与亲水性材料直接共混是较为高效的途径.MIP-202是亲水性多孔材料,可用于改善超滤膜的防污染性能.以N,N-二甲基乙酰胺(DMAc)为溶剂,聚乙烯基吡咯烷酮(PVP)为致孔剂,采用非溶剂致相分离法(NIPS)制备了PSf/MIP-202共混超滤膜,研究了MIP-202的含量对PSf超滤膜结构与性能的影响.通过XRD、SEM、FTIR、接触角、水通量、孔隙率和平均孔径等测试手段对共混改性膜进行表征测试.结果表明,在MIP-202添加质量分数为4%时,膜的综合性能最优,共混超滤膜的水接触角从81°降低至70°,纯水通量达到550 L/(m^(2)·h),是PSf原膜纯水通量[300 L/(m^(2)·h)]的1.8倍.该膜对牛血清白蛋白保持了95%以上的高截留率,通量恢复率从42%增加到75%,抗污染性能较PSf原膜明显提高.

磺化聚三氟苯乙烯对不同溶剂体系制备聚砜超滤膜结构及性能影响研究

本文以聚砜(PSF)为膜材料,磺化聚三氟苯乙烯(SPTFS)为改性剂,采用不同溶剂N,N-二甲基乙酰胺(DMAc)、N,N-二甲基甲酰胺(DMF)、N-甲基吡咯烷酮(NMP)制备了改性聚砜膜。采用扫描电镜、接触角测量仪、孔径分析仪和死端过滤系统研究SPTFS和溶剂对膜结构和性能的影响。研究表明,SPTFS的引入能够改变膜结构,SPTFS改性膜由纯聚砜膜的指状孔结构转变为胞腔状孔或海绵状孔结构。同时,SPTFS能够改善聚砜膜的渗透性能,以DMAc、DMF、NMP为溶剂改性的聚砜膜水通量分别提升了618.7、127.5、194.0 L/(m^(2)·h),同时蛋白质截留率均高于97%,显示出优异的分离性能。

抗污染超滤膜的研制

本文研制了氯甲基化／季铵化聚砜与聚偏氟乙烯共混超滤膜用于阴极电泳漆超滤系统。首先优化了氯甲基化／季铵化聚砜超滤膜的制备工艺，在此基础上，用聚偏氟乙烯部分代替氯甲基化聚砜制备共混超滤膜。结果表明：氯甲基化／季铵化聚砜与聚偏氟乙烯共混超滤膜不仅具有优良的分离性能。

新型抑菌聚砜超滤膜的制备及性能

将辣素功能结构单体N-(4-羟基-3-甲氧基苯甲基)丙烯酰胺(HMBA)和甲基丙烯酸甲酯(MMA)通过自由基引发合成出抑菌型共聚物P(H-co-M),通过红外吸收光谱和热重分析证实了共聚物的结构.采用共混法将共聚物引入聚砜(PSF)铸膜液中,通过浸没沉淀相转化法制备了新型抑菌超滤膜.考察了P(H-co-M)含量对超滤膜分离性能及抑菌性能的影响.结果表明,当P(H-co-M)质量分数为0.5%时,超滤膜分离性能最佳,对5 mg/L腐殖酸溶液的稳定水通量为122.2 L/(m2.h),截留率为84.4%,与未添加P(H-co-M)的超滤膜相比,分别提高了19.2%和9.2%.改性超滤膜具有较强的抑菌性能,当P(H-co-M)含量为1.0%时,抑菌率最大(约80.7%).

超滤分离纯化麻竹叶黄酮的研究

通过对5种超滤膜的对比研究,选择出切割分子量为50000D的聚砜膜PSF-500对麻竹叶黄酮有较好的分离纯化效果:产品得率高达4.29%,纯度达到44.132%。进而选择运行压力、进料液流速和运行时间等运行参数测定了聚砜膜PSF-500的超滤效果,确定了最佳工艺参数:采用操作压力0.20～0.30MPa,进料液流速0.4m/s,连续运行12h清洗超滤膜。还对聚砜膜PSF-500超滤系统进行了芦丁加样回收率测试,结果表明平均回收率为97.0%,变异系数为1.94%。

PAN／PS共混中空纤维超滤膜研究

本文将聚丙烯腈（ＰＡＮ）和聚砜（ＰＳ）材料共混，采用二甲基甲酰胺（ＤＭＦ）作溶剂，以干－湿纺丝工艺制备中空纤维超滤膜，研究了二种膜材料和溶剂的热力学性质，确定合适的共混体系，并考察相同共混比下共混物浓度对中空纤维超滤膜性能影响。以磷酸三乙酯（ＴＥＰ）和冰醋酸作为添加剂，分别观测其不同含量时膜性能变化规律，认为磷酸三乙酯作为添加剂有一定的优越性。提高铸膜液温度，有助于增强ＰＡＮ－ＰＳ－ＤＭＦ所组成部分互溶体系的混溶性，为中空纤维超滤膜制备提供必要条件。

表面活性剂对超滤膜表面改性的研究

采用三类表面活性剂对聚砜超滤膜进行表面改性．实验结果表明，非离子表面活性剂Ｔｗｅｅｎ２０效果最明显，改善了膜表面的亲水性，提高了通量．

高性能聚砜支撑膜研制

研究了复合用高性能聚砜（ＰＳ） 支撑膜的制备．详细讨论了聚砜制膜液中聚砜和添加剂含量、第二添加剂及其含量、溶剂组成、凝胶浴组成与支撑膜性能的关系．研究结果表明，制膜液中聚砜和添加剂含量对膜性能影响较大；加入第二添加剂，可显著降低聚砜制膜液对环境条件，尤其是环境湿度的敏感性，消除以往制膜过程中易产生的针孔等缺陷，提高了膜的完整性和性能稳定性；使用混合溶剂可有效改善膜的孔结构，提高支撑膜的性能；控制凝胶浴中溶剂含量，可进一步提高聚砜支撑膜连续制备的性能稳定性．

Al_2O_3-聚砜复合超滤膜用于中水处理的研究

为了节约用水,对住宅区的分质排水和城市污水厂的污水(中水)进行处理回用是较为可行的方法．膜分离技术是进行中水回用的有效方法之一,但膜容易被污染,造成通量下降．为此,研究了自制的耐污染Al2O3-聚砜复合膜在中水处理中的应用．分析了操作压力、水温、操作时间和膜清洗对水通量的影响,并对产水水质进行了测试．结果表明,该复合膜的水通量随着操作压力的提高而增大,在相同操作压力下,复合膜的水通量要高于聚砜膜的水通量;复合膜在操作24 h后水通量保持较高;随着水温的升高,复合膜的水通量逐渐加大;适当的清洗工艺可使复合膜具有较长的使用寿命;产水水质达到生活杂用水的水质标准．

膜亲和色谱用于胰蛋白酶抑制剂的分离

分别采用酰化-胺化和氯甲基化-胺化对聚砜进行化学修饰,用相转化法制成平均孔径为450nm的超滤膜,经重氮化反应,共价键合上具有活性的胰蛋白酶。其相对活力可达10200 u/g。每克化学改性聚砜膜上可固载化上15 mg胰蛋白酶。用此酶膜对胰蛋白酶抑制剂进行了亲和分离,一次可得6.5mg纯胰蛋白酶抑制剂。

磺化聚砜改性超滤膜的制备及性能

Using sulfonated polysulfone for raw material and complex additive.Adopting the method of the posture transform to preparation sulfonated polysulfone modified ultrafiltration memebrane.It’s aperture is 400-500?.Structure and separate capability have been investigated.Result show that the sulfonated polysulfone modified ultrafiltration membrane can separate solubility protein in the ferment solution of the erythromycin.Problem of the emulsification in the extraction process of the erythromycin have been resolved.

紫外辐照改性聚砜超滤膜

用紫外辐照的方法改性聚砜超滤膜，紫外辐照后膜性能的变化与辐照时间、改性剂种类、改性剂浓度等有关．聚砜超滤膜经紫外辐照改性后，通量增加、膜的亲水性增强．并讨论了紫外辐照改性超滤膜的机理．

聚砜/聚醚类高聚物共混相容性及超滤膜的研究

研究了由聚砜(PSf)和自制的聚醚类高聚物制备的共混超滤膜的组分相容性、性能及膜结构.利用差示扫描量热仪(DSC)测定了纯PSf、纯聚醚类高聚物以及不同PSf/聚醚类高聚物共混配比制得的超滤膜的玻璃化转变温度(Tg).实验结果表明,PSf与聚醚类高聚物组分在整个配比范围内完全相容.所测定的共混膜的Tg与利用Fox方程得出的理论计算值相一致.PSf/聚醚类高聚物共混膜的水通量要高于纯PSf和纯聚醚类高聚物且截留率几乎没有变化.通过扫描电子显微镜(SEM)观察了膜的形态并对膜的超滤性能进行了解释.