Acrylonitrile-based copolymer membranes containing reactive groups: effects of surface-immobilized poly(ethylene glycol)s on anti-fouling properties and blood compatibility

The anti-fouling properties and blood compatibility of poly(acrylonitrile-co-maleic acid) (PANCMA) membranes were improved by the immobilization of poly(ethylene glycol)s (PEG) on membrane surface. It was found that the reactive carboxyl groups on PANCMA membrane surface could be conveniently conversed into anhydride groups and then esterified with PEG. Chemical and morphological changes as well as biocompatibility on membrane surface were analyzed by Fourier transform infrared spectroscopy, elemental analysis, scanning electron microscopy, water contact angle, protein adsorption, and platelet adhesion. Results revealed that, with the immobilization of PEG, the hydrophilicity and blood compatibility of the acrylonitrile-based copolymer membranes were improved obviously. The molecular weight of PEG had an obvious influence on the properties of the PEG-immobilized membranes. Permeation behaviors for the studied membranes were investigated by water and bovine serum albumin (BSA) filtration experiments. Compared with the original PANCMA membrane, the membrane immobilized with PEG 400 (M_w=400 g/mol) showed a three-fold increase in a BSA solution flux, a 40.4% reduction in total fouling, and a 57.9% decrease in BSA adsorption.     

Surface modification of polypropylene membrane by low‐temperature plasma treatment

Microporous polypropylene membranes were low temperature plasma treated with acrylic acid and allylamine. Parameters of plasma treatment were examined and optimized for the enhancement of membrane performance properties. Excess power damaged the membrane surface and excess monomer flow rate increased the reactor pressure to interfere with the glow discharge. Longer plasma treatment time resulted in even more plasma coating and micropore blocking. The contact angle with water decreased and wettabilities increased with the increase of plasma treatment time. Deposition of the plasma polymer on the membrane surface was confirmed by FTIR/ATR spectra of the treated surface. In determining the flux, the hydrophilicity of the surface played a role as important as that of the micropore size. Adequate plasma treatment could enhance both water flux and solute removal efficiency. Results from the BSA (bovine serum albumin) solution test confirmed that fouling was greatly reduced after the plasma treatment. The BSA solution flux through the plasma‐treated membranes depended on pH, whereas pH variation had no serious effects on the untreated membrane. Modification of the surface charge by the plasma treatment should exert a substantial influence on the adsorption and removal of BSA. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1555–1566, 2001     

Polyethersulfone-polyvinylpyrrolidone composite membranes:Effects of polyvinylpyrrolidone content and polydopamine coating on membrane morphology,structure and performances

Hydrophilic modification is a promising method to inhibit fouling formation on ultrafiltration membrane.In this work,different mass concentrations (1％-16％) of hydrophilic polyvinylpyrrolidone were incorpo-rated into polyethersulfone (PES) membranes fabricated by none-solvent induced phase separation.Then,polydopamine (PDA) coating on the surface of prepared membrane was carried out at pH 8.5.The mor-phology and structure,surface hydrophilicity,permeation flux,BSA rejection,antifouling and stability performances of PES and PDA/PES modified membranes were investigated in detail.The results indicated that PDA was successfully attached onto the membranes.Membrane hydrophilicity was evaluated by water contact angle measurement.The contact angles of modified membranes reduced remarkably,sug-gesting that the membrane hydrophilicities were significantly increased.The results of filtration tests,which were done by dead-end filtration of bovine serum albumin solution,showed that the properties of permeability and fouling resistance were obviously improved by PDA modification.When polyvinylpyrrolidone mass content reached 10％,flux recovery ratio of modified membrane was up to 91.23％,and its BSA rejection were over 70％.The results of stability tests showed that the modified mem-branes had good mechanical stability and chemical stability.This facile fabrication procedure and out-standing performances suggested that the modified membranes had a potential in treating fouling.     

Investigating the effect of zirconium-based and titanium-based metal–organic frameworks nanoparticles on the performance of polysulfone hollow fiber mixed matrix membrane for dialysis application

This study aims to investigate polysulfone (PSF) mixed matrix membranes (MMMs) properties containing zirconium-based and titanium-based metal–organic frameworks (MOFs). for hemodialysis application. The nanoparticles were synthesized, and the membranes were produced by the phase inversion method. Membrane characterization conducted by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), field emission Scanning electron microscope (FE-SEM), energy-dispersive x-ray analysis (EDX), transmission electron microscopy (TEM), x-ray diffraction (XRD), and atomic force microscopy (AFM) confirmed the presence of MOF nanoparticles. Also, the evaluation of the specific surface area of nanoparticles was done by BET. The water contact angle reduced from 64.4° to 51.2°, indicating the hydrophilicity improvement, enhancing the pure water flux from 46.8 L/m²h for the pristine membrane to 76.7 L/m2h for the pristine membrane M₄. The total fouling resistance decreased from 30% to 21%, and the bovine serum albumin (BSA) adsorption of modified membranes was lower than that of the pristine membrane. Urea and creatinine were cleared significantly for modified ones, up to 82.6% and 72.1%, respectively, and all membranes showed BSA retention of more than 93%. A comparison between MMMs that contained UIO-66-NH₂ and MIL-125-NH₂ showed that the former had a better effect on the performance. M₄ had better results, indicating high water flux, the lowest fouling resistance, high porosity, lower BSA adsorption, proper clearance for urea and creatinine, and 94.2% BSA retention.     

Hydrophilic Modification of PVDF Microfiltration Membrane with Poly (Ethylene Glycol) Dimethacrylate through Surface Polymerization

The hydrophilic modification of poly (vinylidene fluoride) (PVDF) membrane with poly (ethylene glycol) dimethacrylate (PEGDMA) through grafting reaction for antifouling was reported. The influence of PEGDMA content, reaction temperature and time, on the structure, morphology, antifouling, and hydrophilicity of PVDF-g-PEGDMA membrane has been investigated. The PEGDMA monomers that were grafted on the surface of PVDF microfiltration membrane were confirmed by Attenuation total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS), and morphology study conducted by SEM revealed the changes before and after modification. The protein adsorption, filtration performance, water content, and dynamic contact angle were used to characterize the antifouling and hydrophilicity of the modified PVDF membranes. Compared with the pristine PVDF membrane, the bovine serum albumin (BSA) adsorption on the PVDF-g-PEGDMA membrane decreased about 80%, and the water contact angle of the membrane dropped to 0°. Besides, the experimental results revealed no significant differences between the membrane samples with respect to pore size.     

Enhanced hydrophilic polysulfone hollow fiber membranes with addition of iron oxide nanoparticles

Membranes are at the heart of hemodialysis treatment functions to remove excess metabolic waste such as urea. However, membranes made up of pure polymers and hydrophilic polymers such as polyvinylpyrrolidone suffer problems of low flux and bio‐incompatibility. Hence, this study aimed to improve polysulfone (PSf ) membrane surface properties by the addition of iron oxide nanoparticles (IONPs ). The membrane surface properties and separation performance of neat PSf membrane and membrane filled with IONPs at a loading of 0.2 wt% were investigated and compared. The membranes were characterized in terms of morphology, pure water permeability (PWP ) and protein rejection using bovine serum albumin (BSA ). A decrease in contact angle value from 66.62° to 46.23° for the PSf /IONPs membrane indicated an increase in surface hydrophilicity that caused positive effects on the PWP and BSA rejection of the membrane. The PWP increased by 40.74% to 57.04 L m^?2 h^?1 bar^?1 when IONPs were incorporated due to the improved interaction with water molecules. Furthermore, the PSf /IONPs membrane rejected 96.43% of BSA as compared to only 91.14% by the neat PSf membrane. Hence, the incorporation of IONPs enhanced the PSf hollow fiber membrane hydrophilicity and consequently improved the separation performance of the membrane for hemodialysis application. © 2017 Society of Chemical Industry     

Preparation and properties of PPSU/GO mixed matrix membrane

Polyphenylene sulfone/graphene oxide (PPSU/GO)mixed matrix membraneswith different GOcontents are prepared by phase inversion technique using, PEG-1000 as porogen, and N,N-dimethylacetamide (DMAC) as solvent. The hydrophilicity and pure water flux of the membrane are investigated. The morphology, hydrophilicity, thermodynamic stability and compatibility of the membranes are characterized by various techniques such as SEM, TGA, FTIR and so on. The permeation properties of the membrane are measured in terms of pure water flux and bovine serum albumin (BSA) retention. The results indicate that when the GO content is 1.5 wt%, an evenly distributed finger structure has been formed in the mixed matrix membranes. Owing to the presence of GO, the hydrophilicity and the thermal stability of the membranes are improved, and the fouling resistance is also enhanced.     

石墨烯量子点纳滤膜的仿生修饰及稳定性研究

亲水修饰是提高纳滤膜抗污染性能的重要方法。采用氯化胆碱（ChC）对石墨烯量子点（GQDs-TMC）纳滤膜进行后处理仿生修饰,模拟细胞膜上磷酰胆碱的两性离子抗污染表面。红外光谱（FTIR）和表面元素分析（EDS）表明ChC以共价键结合在纳滤膜分离层上。提高反应温度和氯化胆碱溶液浓度,可以增加纳滤膜的仿生修饰程度。ChC的季铵基团与GQDs-TMC纳滤膜分离层羧基基团形成两性离子结构,提高了仿生修饰（GQDs/ChC-TMC）纳滤膜的亲水性,降低了表面电势,提高了对染料分子和二价盐离子的截留率,并且显著增强了抗污染性能。经过酸、碱和氧化剂溶液浸泡处理及高温纳滤膜分离实验,GQDs/ChC-TMC纳滤膜的渗透率和截留率均未发生较大改变,表明仿生纳滤膜具有优异的化学稳定性和耐热稳定性。     

Thermal conductivity of PVDF/PANI-nanofiber composite membrane aligned in an electric field

Poly(vinylidene fluoride)(PVDF) is a semi-crystalline thermoplastic polymer with excellent thermal stability,electrochemical stability and corrosion resistance, which has been widely studied and applied in industrial nonmetallic heat exchanger and piezoelectric-film sensor. In this study, polyaniline(PANI) nanofibers were synthesized using dodecylbenzene sulfonic acid as the surfactant. The obtained PANI nanofibers were blended in PVDF matrix to enhance thermal conductivity and tensile strength of composite materials. Electric field was applied for the orientation of membrane structure during membrane formation. Scanning electron microscope(SEM) images exhibited that the PANI nanofibers were well-dispersed in the composite membranes. The structure of composite membranes was more orderly after alignment. X-ray diffraction(XRD) and differential scanning calorimetry(DSC) indicated that the content of PANI nanofibers contributed to the transformation of PVDF from α-phase to β-phase. Both the tensile strength and thermal conductivity of composite membranes were significantly improved. This tendency was further enhanced by the application of electric field. The maximum tensile strength was obtained when the content of PANI nanofibers was 3 wt%, which was 46.44% higher than that of pure PVDF membrane. The maximum thermal conductivity of composite membranes after alignment was 84.5% greater than that of pure PVDF membrane when the content of PANI nanofibers was 50 wt%. The composite membrane is a promising new potential material in heat transfer field and the mechanism explored in this study would be informative for further development of similar thermal conductive polymeric materials.     

Electro-Cross-Flow Ultrafiltration System for the Rejection of Nickel Ions from Aqueous Solution,and Sugeno Fuzzy Model Simulation

An empirical model was developed using the experimental results, to predict the removal of nickel ions under the effect of an external electric field applied to an ultrafiltration membrane, electroultrafiltration (EUF) process. Two commercial membranes from Millipore PLCC5 (regenerated cellulose, 5 kDa) and PBCC5 (polyethersulfone, 5 kDa) were selected to conduct the experiments. The rejection of nickel ions increases with an increment of the applied voltage. The maximum rejection of the metal was found to be 60% obtained with the PBCC5 membrane and applying a potential difference of 3.5 and 4.5 V. The results have shown that the application of an external electric field increases the removal capacity of UF membranes and enhances EUF system efficiency. The experimental data for removal of nickel ions in the system were analyzed using the Takagi–Sugeno–Kang (TKS) fuzzy model. The goodness of fit for the TKS fuzzy model used was at least 98%.     

Tailoring the ionic transfer characteristics of polyvinyl chloride-based heterogeneous ion exchange membranes by embedding carboxy methyl cellulose in membrane channels

Polyvinyl chloride-based heterogeneous cation exchange membranes were modified by embedding carboxy methyl cellulose in ionic transfer channels of membrane. The effect of CMC to PVC blend ratios on properties of membranes was studied. SOM images showed uniform distribution and surfaces for prepared membranes relatively. The SEM images showed uniform and dense structure for the membranes. The XRD pattern also demonstrated amorphous structure for the membranes. Membrane water content was improved from 25 to 39 % by increase of CMC concentration up to 32 %wt. Similar trend was found for membrane surface hydrophilicity. The membrane ion exchange capacity, fixed ion concentration, membrane potential, charge density, transport number, permselectivity, and ionic flux were enhanced initially by increase of CMC ratio up to 16 %wt and then began to decrease by increase in CMC concentration from 16 to 32 %wt. The membrane oxidative stability and areal electrical resistance showed decreasing trends by utilizing of carboxy methyl cellulose in the membrane matrix. Membrane transport number and selectivity were also increased by increase of electrolyte concentration. Similar trend was found for the membrane electrical conductivity by increase of electrolyte concentration. Also prepared membranes showed higher transport number, selectivity, and areal electrical resistance at pH 7 compared to other pH values.     

Effect study of hexagonal mesoporous silica/polyaniline nanocomposite on the structural properties of polysulfone membranes and its heavy metal removal efficiency

New mixed matrix membranes of polysulfone were synthesized by different content of hexagonal mesoporous silica coated by polyaniline and used for nickel and lead ion removal. The membranes were characterized by FESEM, XRD, BET, TGA, and FTIR, and zeta potential measurements. The results showed that PANi/HMS particles enhanced the membrane porosity and permeability. These effects were explained according to an increase of the membrane hydrophilicity due to the formation of new functional groups during membrane casting. The results showed that metal ion rejection was performed by a filtration–adsorption mechanism, resulting in fixation of metal ions on the active sites of membranes.     

Effects of pre-oxidant (KMnO4) on structure and performance of PVDF and PES membranes

The structure and performance of membrane materials are very important to the efficient and stable operation in membrane drinking water purification technology. Potassium permanganate (KMnO₄), which can change the characteristics of organic matters and control membrane surface fouling, has been widely used as pre-oxidant in the front of membrane drinking water process. This study investigates the evolution of membrane surface structure and performance when polyvinylidene fluoride (PVDF) and polyethersulfone (PES) were exposed to 10, 100 and 1000 mg·L^-1 KMnO₄ solution for 6 and 12 d, respectively. The aged membrane physicochemical characteristics such as membrane surface morphology, chemical composition, hydrophilicity, porosity and zeta potential were evaluated by modern analytical and testing instruments. The anti-fouling property of membrane surface was also investigated by the filtration-backwash experiment. The results indicated that the different concentrations and exposure time of KMnO₄ led to a different variation on PVDF and PES membrane surface structure and performance, which could further affect the membrane separation performance and the membrane fouling behaviors. The membrane surface pore size and porosity increased due to the dislodgment and degradation of membrane additive (PVP), which improved membrane permeability and enhanced the adsorption and deposition of pollutants in the membrane pores. With the increase of exposure time, the membrane surface pore size and porosity reduced for the reactions of chain scission and crosslinking on membrane materials, and the backwashing efficiency declined, leading to a more serious irreversible fouling. Compared with PVDF membranes, the formation of sulfonic group for PES membranes increased the negative charge on membrane surface due to the oxidation of KMnO₄. The present study provides some new insights for the regulation of the pre-oxidant dose and the selection of the membrane materials in KMnO₄ pre-oxidation combined with membrane filtration system.     

PEI/EVAL blend membranes for granule neuronal cell culture

Recently we developed a novel type of membrane, based on polyethylene vinyl alcohol (EVAL), for biomedical applications. To improve the physical and biological performance of this membrane, polyethylenimine (PEI) that has been widely used as a gene transfer vector was chosen to blend with EVAL in this study. The properties and in vitro neuronal interaction of the blend membranes were investigated. Scanning electron microscopic observations show that the membranes exhibited increasingly smoother surface morphologies as the PEI content increased. Differential scanning calorimetric analysis demonstrated that EVAL was compatible with PEI at the microscopic level and the crystallinity of EVAL membrane was reduced by amorphous PEI. The surface nitrogen to carbon ratios, surface positive charges, surface hydrophilicity and surface protein adsorption were found to increase with increasing PEI content in the blend membranes as evidenced by the evidences from electron spectroscopy for chemical analysis as well as measurements of zeta potential, water contact angle, and serum protein adsorption respectively. From the morphology and viability of neurons cultured on the surfaces, it was observed that the neurons adhered, spread, grew and differentiated more onto the moderately hydrophilic PEI-containing membranes than onto the unmodified and hydrophobic EVAL. These PEI/EVAL blend membranes, which displayed high compatibility, thermal stability, moderate hydrophilicity, improved serum protein adsorption and enhanced neuronal interaction, may offer the potential to improve the healing and axonal regeneration of injured neuronal tissues.     

Preparation and Characterization of Heterogeneous Cation Exchange Membranes Based on S-Poly Vinyl Chloride and Polycarbonate

This research deals with the preparation of heterogeneous cation exchange membranes by solution-casting techniques using S-polyvinylchloride (S-PVC) and polycarbonate (PC) as binders, cation exchange resin powder as functional groups agent, and tetrahydrofuran as solvent. The effects of polymer binder type and resin ratio loading on morphological, electrochemical, and mechanical properties of prepared membranes were studied and evaluated. Scanning electron microscopy and scanning optical microscopy were used for the membranes structure investigation. Images showed that increase of resin loading in casting solution resulted in a highly uniform phase forming. Moreover resin particles were distributed more uniformly in polycarbonate membranes compared to the polyvinylchloride ones. The water content, surface hydrophilicity, ion exchange capacity, ion concentration, permselectivity, membrane potential, surface charge density, transport number, ionic permeability, flux of ions, and current efficiency were enhanced for the prepared membranes by increase in resin ratio loading. Moreover, the increase of resin ratio in casting solution reduced the mechanical strength of the prepared membranes. The mechanical strength of S-PVC membrane was higher than the PC ones. Furthermore, the increment of resin content caused some decreases in areal electrical resistance and oxidative stability of the prepared membranes. Home-made membranes exhibited appropriate electrochemical properties in comparison with a tested commercial heterogeneous cation exchange membrane in the same experimental conditions. Swelling of the prepared membranes was also negligible compared to the commercial type.     

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...     

Effect of hydrophilic poly(ethylene glycol) methyl ether additive on the structure,morphology, and performance of polysulfone flat sheet ultrafiltration membrane

In this work, effects of hydrophilic poly(ethylene glycol) methyl ether (PEGME) 5000 additive on the structure, morphology, and performance of polysulfone (PSF) membrane have been investigated. The membranes are prepared with direct blending of PEGME5000 (0–9 wt %) with two compositions of PSF (12 and 15 wt %) into N-methyl-2-pyrrolidone and further characterized in terms of morphology, structure, fouling, and ultrafiltration performance. The ternary phase diagram is plotted to investigate the thermodynamic stability of the system. Moreover, protein adsorption tests are conducted using bovine serum albumin (BSA) to see the effect of PEGME5000 on surface hydrophilicity. The ultrafiltration experiments are performed using humic acid (HA) solution and oil-in-water (o/w) emulsion. The result showed that, the contact angle decreased from 64° to 46° and from 67.6° to 49° for 12M and 15M membranes, respectively, indicating an improved hydrophilicity. The 12M and 15M membranes with 9 wt % of PEGME5000 have the lowest BSA adsorption due to highest antifouling property. The maximum permeability was obtained 0.72 and 0.51 L/m² h kPa for 12M5 and 15M3, respectively, due to maximum porosity which is also supported by the morphological result. In HA permeation, 12M5 and 15M3 achieved a maximum Flux _RR around 0.95 and 0.91, respectively, which was remarkably higher compared to 0.61 and 0.62 Flux _RR of 12M0 and 15M0. Also, PEGME5000 significantly affected the structure and morphology of the membranes. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47163.     

Surface modification of polypiperazine-amide membrane by self-assembled method for dye wastewater treatment☆

Polypiperazine-amide membranes were modified with poly(ethyleneimine) (PEI) by self-assembled method, through which PEI molecules were fixed on the membrane surface by ionic interaction. In the experiments, the PEI concentration ranged from 50 to 2000 mg·L?1 while the depositing time was fixed at 20 min. The results showed that low PEI concentration resulted in a slight increase of pure water flux, which was attributed to the enhanced membrane surface hydrophilicity. The PEI adsorption on membrane surface had less effect on the re-jections to neutral PEG and sucrose, but improved the rejections to divalent cationic ions and methylene blue as the result of reversion of the membrane surface charge from negative to positive according to the XPS analysis and zeta potential measurements. The membrane modified at PEI=1500 mg·L?1 exhibited high rejection to methylene blue (MB) and is potential to be applied in the treatment of effluents containing positively charged dyes.     

Anti‐biofouling anion exchange membrane using surface modified quaternized poly(ether imide) for microbial fuel cells

This article deals with a novel way of improving the anti‐biofouling potential of an anion exchange membrane (AEM) by surface modification with ethanol amine (AEOH), a low cost material without affecting the chemical structure and morphology of Quaternized Poly(ether imide) ( QPEI), the host membrane. The anti‐biofouling potential of the AEM was evaluated using bacteria anti‐adhesion test, hydrophilicity, surface roughness, water uptake, and the AEOH modification time. The data reveal that power density in all MFCs attain the highest in the sixth batch and thereafter declined albeit in a varying rate as expected measuring the least for QPEI‐30. Periodical measurement of internal resistance and protein content on the membrane surfaces were found to be the least for QPEI‐30 when compared with others. A reduced biofouling with improved anti‐biofouling property is attributed to the enhanced hydrophilicity due to surface modification. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44432.     

Preparation of blend polyethersulfone/cellulose acetate/polyethylene glycol asymmetric membranes for oil–water separation

Blend PES/CA hydrophilic membranes were prepared via a phase-inversion process for oil–water separation. PEG-400 was introduced into the polymer solution in order to enhance phase-inversion and produce high permeability membranes. A gas permeation test was conducted to estimate mean pore size and surface porosity of the membranes. The membranes were characterized in terms of morphology, overall porosity, water contact angle, water flux and hydraulic resistance. A cross-flow separation system was used to evaluate oil–water separation performance of the membranes. From FESEM examination, the prepared PES/CA membrane presented thinner outer skin layer, higher surface porosity with larger pore sizes. The outer surface water contact angle of the prepared membrane significantly decreased when CA was added into the polymer solution. The higher water flux of the PES/CA membrane was related to the higher hydrophilicity and larger pore sizes of the membrane. From oil–water separation test, the PES/CA membrane showed stable oil rejection of 88 % and water flux of 27 l/m² s after 150 min of the operation. In conclusion, by controlling fabrication parameters a developed membrane structure with high hydrophilicity, high surface porosity and low resistance can be achieved to improve oil rejection and water productivity.