Poly(arylene sulfide sulfone) hybrid ultrafiltration membrane with TiO2‐g‐PAA nanoparticles: Preparation and antifouling performance

Poly(arylene sulfide sulfone) (PASS) is a kind of newly developed polymeric membrane material which has excellent mechanical strength, thermal stability, and solvent resistance. And, it would be a potential material for high temperature ultrafiltration and organic solvent filtration. In this article, PASS hybrid ultrafiltration membrane with improved antifouling property was prepared by mixing TiO₂ nanoparticles which were grafted with polyacrylic acid (PAA). These membranes were prepared by a phase inversion technique and their separation performance and antifouling property of the prepared membranes were investigated in detail by SEM, FTIR, EDS, contact angle goniometry, filtration experiments of water, and BSA solution. The results shown that the TiO₂‐g‐PAA nanoparticles dispersed well in membrane matrix, the hydrophilicity of the membranes prepared within TiO₂‐g‐PAA nanoparticles have been improved and these membranes exhibited excellent water flux and antifouling performance in separation than that of the pure PASS membranes and PASS membranes with TiO₂ nanoparticles. More specifically, among membrane sample M0, M1.5, and MP1.5, MP1.5 which contained 1.5 wt% TiO₂‐g‐PAA exhibited the highest water permeation (190.4 L/m² h at 100 kPa), flux recovery ratio, and the lowest BSA adsorption amount. POLYM. ENG. SCI., 55:2829–2837, 2015. © 2015 Society of Plastics Engineers     

Asymmetric membranes fabricated from poly(acrylonitrile‐co‐N‐vinyl‐2‐pyrrolidone)s with excellent biocompatibility

Poly(acrylonitrile‐co‐N ‐vinyl‐2‐pyrrolidone)s (PANCNVPs) show excellent biocompatibility. In this work, PANCNVPs with different contents of N‐vinyl‐2‐pyrrolidone (NVP) were fabricated into asymmetric membranes by the phase inversion method. The surface chemical composition of the resultant membranes was determined by Fourier transform infrared spectroscopy–attenuated total reflection. Field emission scanning electron microscopy was used to examine the surface and cross section morphologies of the membranes. It was found that the morphologies hardly change with the increase of NVP content in PANCNVP, while the deionized water flux increases remarkably and the bovine serum albumin (BSA) retention decreases slightly. Experiment of dynamic BSA solution filtration was carried out to evaluate the antifouling properties of the studied membranes. The relative flux reduction of PANCNVP membrane containing 30.9 wt % of NVP is 25.9%, which is far smaller than that of the polyacrylonitrile membrane (68.8%). Results deduce that this improvement comes from the excellent biocompatibility of NVP moieties instead of the hydrophilicity change, because the water contact angles of these membranes fluctuate between 60 and 70°. Results from the membranes using poly(N‐vinyl‐2‐pyrrolidone) (PVP) as an additive confirm that, to a certain extent, the PANCNVP membranes show the advantages of antifouling compared with the polyacrylonitrile/PVP blending membrane. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4577–4583, 2006     

Preparation of PVDF/poly(tetrafluoroethylene‐co‐vinyl alcohol) blend membranes with antifouling propensities via nonsolvent induced phase separation method

Poly(vinylidene fluoride) (PVDF) was blended with a new amphiphilic copolymer, poly(tetrafluoroethylene‐co‐vinyl alcohol) [poly(TFE‐VA)], via non‐solvent induced phase separation (NIPS) method to make membranes with superior antifouling properties. The effects of the VA/TFE segment ratio of the copolymer and the copolymer/PVDF blend ratio on the properties of the prepared membranes were studied. Membranes with similar water permeabilities, surface pore sizes, and rejection properties were prepared and used in bovine serum albumin (BSA) filtrations with the same initial water flux and almost the same operating pressure, to evaluate the sole effect of membrane material on fouling propensity. While the VA/TFE segment ratio strongly affected the membrane antifouling properties, the effects of the copolymer/PVDF blending ratio were not so drastic. Membrane surface hydrophilicity increased, and BSA adsorption and fouling decreased upon blending a small amount of amphiphilic copolymer with a high VA/TFE segment ratio with PVDF (copolymer/PVDF blending ratio 1:5). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43780.     

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.     

Enhanced water flux through ultrafiltration polysulfone membrane via addition‐removal of silica nano‐particles: Synthesis and characterization

In the present paper, hierarchically structured ultrafiltration polysulfone (PSf) membrane was prepared to explore the effect of addition and subsequent removal of SiO₂ nano‐particles on the membrane morphology, hydrophilicity, and separation properties. The PSf based membranes namely PSf, PSf/SiO₂ and PSf/WSiO₂ (i.e. SiO₂ nano‐particles was acid‐washed and removed from PSf/SiO₂), were synthesized and characterized by different characterization methods. Pure water flux through the membranes was determined using a filtration unit operating at a continuous dead‐end flow mode. The modification enhanced the morphology, hydrophobicity, porosity and transport properties of the modified membranes, although the molecular weight cut‐off (MWCO) of the membranes was not changed considerably. In comparison, PSf/WSiO₂ membrane exhibited excellent pure water flux (about 4.5 times the flux of PSf, and 17 times the flux of PSf/SiO₂), although antifouling property of PSf/SiO₂ in separation of bovine serum albumin (BSA) was better than that of PSf and PSf/WSiO₂ membranes. The results suggested that the addition/removal of sacrificial solid fillers within/from a membrane matrix may provide a promising strategy to enhance PSf membrane transport property. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43556.     

Fabrication and performance of a polyethersulfone nanofiltration membrane impregnated with a mesoporous silica–poly(1‐VInylpyrrolidone) nanocomposite

Fouling is a serious problem in the membrane formation process. Adding hydrophilic polymers or inorganic particles into the membrane is an effective way for improving the antifouling performance. However, most of the water‐soluble polymeric additives leach out during the phase inversion process, and the inorganic particles are prone to agglomerate in the membrane, which decreases the antifouling property of the membrane. In this study, poly(1‐vinylpyrrolidone) (PVP) was grafted onto mesoporous silica (MS) nanoparticle surface, and polyethersulfone (PES)/MS–PVP nanocomposite membranes were fabricated by the phase inversion method. MS–PVP dispersed well on the membrane surface, and the hydrophilicity of the PES/MS–PVP membranes increased with increasing content of MS–PVP. PES/MS–PVP membranes exhibited higher water flux than that of the bare PES membrane without any loss in NaCl rejection, and water flux of 25 L/m²h could be achieved by the membrane containing 3% of MS–PVP, which is almost 1.5 times as high as that of bare PES membrane at 0.6 MPa. The protein adsorption onto the membrane surface declined significantly from 49 to 25 mg/cm² when the MS–PVP loading increased from 0% to 3%. POLYM. COMPOS., 38:908–917, 2017. © 2015 Society of Plastics Engineers     

Surface modification of UHMWPE/fabric composite membrane via self‐polymerized polydopamine followed by mPEG‐NH2 immobilization

In this work, a novel approach to improve the antifouling properties of membrane surfaces was developed. First, a polydopamine layer was attached onto the surface of an ultrahigh molecular weight polyethylene/fabric composite microporous membrane based on dopamine self‐polymerization and adhesive behavior. Then, methoxy polyethylene glycol amine was covalently bonded with the polydopamine layer via a Schiff base reaction. The physicochemical properties of the modified composite membrane surface were investigated, and the results indicated this modification could effectively enhance the membrane surface hydrophilicity. Furthermore, the protein fouling resistance of both dopamine‐coated and methoxy polyethylene glycol amine immobilized composite membranes was evaluated. It was found that a dopamine coating cannot obviously enhance the membrane antifouling properties due to its strong bioadhesion behavior. However, the antifouling properties of the composite membranes were significantly improved after being immobilized with a methoxy polyethylene glycol amine layer. Consequently, a layer‐by‐layer modified composite membrane with excellent antifouling property was obtained. The pure water flux and flux recovery ratio of the resultant membrane were 764 L m^?2 h^?1 and 83%, respectively. The aim of this paper was to provide an effective approach to optimizing the separation efficiency and antifouling performance of the ultrahigh molecular weight polyethylene/fabric composite membrane. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46428.     

High‐performance composite nanofiltration membranes fabricated via ternary mixture: Complementary preponderance of the fluorine‐containing monomer 2,2′‐bis(1‐hydroxyl‐1‐trifluoromethyl‐2,2,2‐triflutoethyl)‐4,4′‐methylene dianiline and the rigid monomer bisphenol F

In a previous study, we proved that tailoring the polyamide backbone stiffness is an effective way to fabricate high‐performance polyamide nanofiltration (NF) membranes. However, in the previous study, we mainly focused on the flat membrane and did not consider its chlorine tolerance. In this study, by regulating the aqueous‐phase compositions in the interfacial polymerization process, chlorine tolerance on NF hollow‐fiber membranes was endowed while the membrane performance stayed high. The experimental results show that when the ratio of Piperazine (PIP)–bisphenol F (BPF)/2,2′‐bis(1‐hydroxyl‐1‐trifluoromethyl‐2,2,2‐triflutoethyl)‐4,4′‐methylene dianiline (BHTTM) was 5:1:4, the NF membrane possessed a permeate flux of 21.0 L m^?2 h^?1 bar^?1 and an Na₂SO₄ rejection up to 90.0%. X‐ray photoelectron spectroscopy analysis also confirmed that the polymerization degree of the PIP–BPF–BHTTM NF membrane was the highest. Moreover, the NF membrane could tolerate active chlorine to over 10,000 ppm h Cl. After the active chlorine treatment, the permeate flux increased over 30.0 L m^?2 h^?1 bar^?1, and the Na₂SO₄ rejection was about 90.0%. Although the PIP–BHTTM NF membrane also possessed good chlorine tolerance, its permeate flux (after active chlorine treatment) was only 60% of that of the PIP–BPF–BHTTM NF membrane. Therefore, the PIP–BPF–BHTTM NF membrane possessed a combination of high flux and high chlorine tolerance and showed good potential in water treatment in rigorous environments. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46482.     

Fabrication of antifouling membranes by blending poly(vinylidene fluoride) with cationic polyionic liquid

Membrane fouling problem is now limiting the rapid development of membrane technology. A newly synthesized cationic polyionic liquid (PIL) [P(PEGMA-co-BVIm-Br)] was blended with poly(vinylidene fluoride) (PVDF) to prepare antifouling PVDF membranes. The PVDF/P(PEGMA-co-BVIm-Br) exhibited an increased surface hydrophilicity, the water contact angle was reduced from 77.8° (pristine PVDF) to 57.9°. More porous membrane structure was obtained by adding PIL into the blending polymers, as high as 478.0 L/m²·h of pure water flux was detected for the blend PVDF membrane in comparison with pristine PVDF (17.2 L/m²·h). Blending of the cationic PIL with PVDF gave a more positive surface charge than pristine PVDF membrane. Blend membranes showed very high rejection rate (99.1%) and flux recovery rate (FRR, 83.0%) to the positive bovine serum albumin (BSA), due to the electrostatic repulsion between the membrane surface and proteins. After three repeated filtration cycles of positive BSA, the blend PVDF membranes demonstrated excellent antifouling performance, the permeation flux of the membranes was recovered very well after a simple deionized water washing, and as high as 70% of FRR was obtained, the water flux was maintained at above 350 L/m²·h. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48878.     

Fabrication of polysulfone nanocomposite membranes with silver‐doped carbon nanotubes and their antifouling performance

In this study, polysulfone (PSf)/silver‐doped carbon nanotube (Ag‐CNT) nanocomposite membranes were prepared by a phase‐inversion technique; they were characterized and evaluated for fouling‐resistant applications with bovine serum albumin (BSA) solutions. Carbon nanotubes were doped with silver nanoparticles via a wet‐impregnation technique. The prepared Ag‐CNT nanotubes were characterized with scanning electron microscopy (SEM)/energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, Raman spectroscopy, and thermogravimetric analysis. The fabricated flat‐sheet PSf/Ag‐CNT nanocomposite membranes with different Ag‐CNT loadings were examined for their surface morphology, roughness, hydrophilicity, and mechanical strength with SEM, atomic force microscopy, contact angle measurement, and tensile testing, respectively. The prepared composite membranes displayed a greater rejection of BSA solution (≥90%) and water flux stability during membrane compaction with a 10% reduction in water flux values (up to 0.4% Ag‐CNTs) than the pristine PSf membrane. The PSf nanocomposite membrane with a 0.2% Ag‐CNT loading possessed the highest flux recovery of about 80% and the lowest total membrane resistance of 56% with a reduced irreversible fouling resistance of 21%. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44688.     

Improving the hydrophilicity of polyethersulfone membrane by the combination of grafting technology and reverse thermally induced phase separation method

In this work, surface grafting modification technology was combined with reverse thermally induced phase separation (RTIPS) method in order to improve the structure and permanent hydrophilicity of polyethersulfone (PES) membranes. Acrylic solution with different concentrations was grafted on the surface of PES membranes while grafting temperature and grafting time were also varied. The modified PES membranes were characterized in all aspects. Attenuated total reflectance Fourier transform-infrared confirmed successful modification of the PES membrane by grafting acrylic acid. Scanning electron microscopy revealed that homogeneous porous top surface as well as spongy-like cross-section structure appeared in the membrane by RTIPS procedure. Moreover, porosity was affected by changes of acrylic acid concentration, grafting temperature, and grafting time. Atomic force microscopy showed that grafting acrylic acid gave a reduction in roughness of PES membrane. Combined with the decreased values of contact angle, the hydrophilicity and antifouling performance of the PES membrane were improved. The pure water flux and BSA rejection rate of the grafted PES membranes were remarkably improved for pure PES membrane and attained a maximum, which was 1,646.24 L/(m²h) and 94.5%, respectively. The long-term test demonstrated that grafting membranes exhibited outstanding elevated water flux recovery ratio (>85%).     

Development of a high-performance polysulfone hybrid ultrafiltration membrane using hydrophilic polymer-functionalized mesoporous SBA − 15 as filler

A novel polysulfone hybrid ultrafiltration membrane was developed by blending hydrophilic poly[poly(ethylene glycol) methyl ether methacrylate] [P(PEGMA)] grafted mesoporous SBA-15 [SBA-g-P(PEGMA)] as filler. The hydrophilic SBA-g-P(PEGMA) fillers were synthesized via surface-initiated atom transfer radical polymerization. The effects of the SBA-g-P(PEGMA) fillers on the prepared hybrid membranes were systematically investigated. Compared with pristine SBA-15 fillers, SBA-g-P(PEGMA) fillers contributed to higher hydrophilicity and a more developed pore structure in the hybrid membranes. Specifically, SBA-15 grafted with a moderate P(PEGMA) molecular weight could better preserve the valid open-ended filler pore structure in the membrane matrix, thus facilitating membrane permeability. The pure water flux of the as-prepared polysulfone (PSF)/SBA-g-P(PEGMA) membrane was three times that of the PSF/SBA-15 membrane (271.7 L m⁻² h⁻¹ vs. 88.2 L m⁻² h⁻¹) with similar membrane selectivity. Moreover, the PSF/SBA-g-P(PEGMA) membranes showed improved antifouling property. This work paves the way for developing high-performance hybrid membranes by blending of hydrophilic polymer-functionalized mesoporous fillers in the future. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47353.     

Preparation of hydrophilic dimethyl 5‐sodium sulfoisophthalate/poly(ethylene terephthalate) nanofiber composite membranes for improving antifouling properties

In this study, the effect of dimethyl 5‐sodium sulfoisophthalate (SSI) nanoparticles (NPs) on the antifouling properties of poly(ethylene terephthalate) (PET) electrospun nanofiber membranes (ENMs) was investigated through the ultrafiltration of C. I. Basic Blue 3. 3 dye. To reveal the tortuous effect of this additive on the antifouling properties, scanning electron microscopy was used for the characterization of the ENM structure and the optimization of the SSI NP content. Then, some selected physical and structural properties of the membrane, such as the porosity, moisture regain, contact angle, hydraulic permeability (L _p ), and mechanical properties, in the optimized range of SSI NP contents were investigated. Finally, the influence of this additive on the rejection and flux recovery ratio of the prepared membranes was considered. Consequently, the antifouling properties were assessed with consideration of all of the aforementioned parameters. The SSI/PET2 membrane (that with 0.02% w/w SSI NPs with respect to the total amount of PET polymer and SSI NPs), with an average nanofiber diameter of 450 nm, a porosity of 78.44%, a moisture regain of 9.34%, a contact angle of 86.48°, an L _p of 42,167 L h^?1 m^?2 bar^?1, a tensile strength of 4.66 ± 0.04 MPa, a flux recovery ratio of 15.3%, and a final rejection of 95%, showed a significant enhancement in the antifouling properties compared with pristine PET ENMs. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44522.     

Self-doped sulfonated polyaniline ultrafiltration membranes with enhanced chlorine resistance and antifouling properties

Membranes heavily rely on chlorination to diminish (bio)fouling, but chlorination can also lead to membrane degradation. We developed sulfonated polyaniline (S-PANI) ultrafiltration (UF) membranes with improved chlorine resistance and intrinsic antifouling properties. The S-PANI membranes were synthesized through Non-solvent Induced Phase Separation (NIPS). Membrane performance was evaluated under harsh chlorine conditions (250 ppm sodium hypochlorite for 3 days under different pH conditions). The S-PANI membranes showed improved chlorine resistance including a stable performance without changes in model foulant BSA rejection. In contrast, PANI membranes suffered critical structural damage with complete leakage and commercial PES membranes showed a 76% increase in pure water flux and a noticeable change in BSA rejection. Small changes in S-PANI membrane performance could be linked to membrane structural changes with pH, as confirmed by SEM, IR spectroscopy, and contact angle measurements. Additionally, the S-PANI membranes showed better antifouling properties with a high flux recovery ratio in comparison to PANI membranes using alginic acid, humic acid, and BSA model foulants. Chemical cleaning by sodium hypochlorite re-instated the transport properties to its initial condition. Overall, the developed S-PANI membranes have a high chlorine tolerance and enhanced antifouling properties making them promising for a range of UF membrane applications.     

Separation of bovine serum albumin (BSA) using γ‐Al2O3–clay composite ultrafiltration membrane

BACKGROUND: Ceramic membranes have received more attention than polymeric membranes for the separation and purification of bio‐products owing to their superior chemical, mechanical and thermal properties. Commercially available ceramic membranes are too expensive. This could be overcome by fabricating membranes using low‐cost raw materials. The aim of this work is to fabricate a low‐cost γ‐Al₂O₃–clay composite membrane and evaluate its potential for the separation of bovine serum albumin (BSA) as a function of pH, feed concentration and applied pressure. To achieve this, the membrane support is prepared using low‐cost clay mixtures instead of very expensive alumina, zirconia and titania materials. The cost of the membrane can be further reduced by preparing a γ‐alumina surface layer on the clay support using boehmite sol synthesized from inexpensive aluminium chloride instead of expensive aluminium alkoxide using a dip‐coating technique. RESULTS: The pore size distribution of the γ‐Al₂O₃‐clay composite membrane varied from 5.4–13.6 nm. The membrane was prepared using stable boehmite sol of narrow particle size distribution and mean particle size 30.9 nm. Scanning electron microscopy confirmed that the surface of the γ‐Al₂O₃–clay composite membrane is defect‐free. The pure water permeability of the support and the composite membrane were found to be 4.838 × 10^?6 and 2.357 × 10^?7 m³ m^?2 s^?1 kPa^?1, respectively. The maximum rejection of BSA protein was found to be 95%. It was observed that the separation performance of the membrane in terms of flux and rejection strongly depends on the electrostatic interaction between the protein and charged membrane. CONCLUSION: The successively prepared γ‐Al₂O₃‐clay composite membrane proved to possess good potential for the separation of BSA with high yield and could be employed as a low cost alternate to expensive ceramic membranes. Copyright © 2009 Society of Chemical Industry     

原位合成法制备高通量聚砜超滤膜及其性能研究

以聚砜（PSF）为原料,N,N‐二甲基甲酰胺（DMF）为溶剂,4,4'-二氨基二苯砜（DDS）和均苯四甲酸二酐（PMDA）为添加物,在聚砜铸膜液中“原位合成”聚酰胺酸（PAA）,采用浸没沉淀相转化法制备高水通量PSF超滤膜。使用傅里叶变换红外光谱仪（ATR-FTIR）和X射线光电子能谱分析（XPS）对膜表面化学组成进行分析,结果表明成功在膜表面引入PAA。膜的荷电性、水接触角、保湿性和水通量等性能测试表明,改性膜具有良好的保湿性和水渗透性。在0.1 MPa的运行压力下,改性膜的纯水通量和牛血清白蛋白（BSA）截留率均高于纯PSF超滤膜,纯水通量从221.39 L/(m²·h)增加至406.57 L/(m²·h),截留率从75.75%增加到96.14%;在0.01~0.1 MPa的运行压力范围内,改性膜水通量均高于纯PSF超滤膜。。     

Regenerated cellulose membrane prepared with ionic liquid 1‐butyl‐3‐methylimidazolium chloride as solvent using wheat straw

BACKGROUND: Currently, cellulose membranes are prepared by cellulose acetate hydrolysis or chemical derivatization dissolution and regeneration using cotton pulp or wood pulp. In this study, the concept ‘lignocelluloses biorefinery’ was used, and good quality long fiber was fractionated from wheat straw using clean technologies. The objective of this study is to develop wheat straw cellulose to prepare regenerated cellulose membrane with ionic liquid 1‐butyl‐3‐methylimidazolium chloride ([BMIM]Cl) as solvent. RESULTS: Wheat straw cellulose (WSC) fractionated from wheat straw contained 93.6% α‐cellulose and the degree of polymerization (DP) was 580. WSC was dissolved directly without derivatization in [BMIM]Cl. With increase in dissolving temperature, the DP of the regenerated cellulose dropped, which resulted in a decrease in the intensity of regenerated cellulose membrane. After regeneration in [BMIM]Cl, the WSC transformed from cellulose I to cellulose II, and the crystallinity of the regenerated cellulose was lower than the original cellulose. The regenerated WSC membrane had good mechanical performance and permeability, the tensile strength and breaking elongation were 170 MPa and 6.4%, respectively, the pure water flux was 238.9 L m^?2 h^?1 at 0.3 MPa pressure, and the rejection of BSA was stabilized at about 97%. CONCLUSION: Wheat straw cellulose fractionated from wheat straw satisfied the requirement to prepare regenerated cellulose membrane using ionic liquid [BMIM]Cl as solvent. Copyright © 2012 Society of Chemical Industry     

The influence of solvent properties on the performance of polysulfone/β‐cyclodextrin polyurethane mixed‐matrix membranes

This study investigates the effect of solvent properties on the structural morphology and permeation properties of polysulfone/β‐cyclodextrin polyurethane (PSf/β‐CDPU) mixed‐matrix membranes (MMMs). The membranes were prepared by a modified phase‐inversion route using four different casting solvents [dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), dimethyl acetamide (DMA), and N‐methyl‐2‐pyrrolidone (NMP)]. While DMSO‐based membranes demonstrated particularly high permeability (ca 147 L/m²h.bar), their crystallinity was low compared to MMMs prepared using DMA, DMF and NMP due to the formation of thin active layers on their surfaces. Cross‐sectional morphology revealed that the MMMs have a dense top skin with finger‐like inner pore structures. Membranes prepared using NMP displayed the highest hydrophilicity, porosity, and crystallinity due to the low volatility of NMP; DMF membranes exhibited superior mechanical and thermal stability due to its (DMF) high hydrogen bonding (δH) values. Thus, the morphological parameters, bulk porosity, and flux performance of MMMs have a significant inter‐relationship with the solubility properties of each solvent (i.e., δH, density, volatility, solubility parameter). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2005–2014, 2013     

Separation of Humic Substances by Porous Ion-Exchange Membranes from Sulfonated Polysulfone

Abstract

Ultrafiltration involving sulfonated polysulfone membranes provides high efficiency for humic matter removal from water. The increase in ion-exchange capacity of the polymer matrix from 0.24 to 0.96 mmol SO₃H groups per 1 g of dry membrane increases the membrane pore diameter and its hydrophilicity, and thus the permeate flux from 0.05 to 3.69 m³/m²·d. In order to decrease the manufacturing cost, membranes from polysulfone and sulfonated polysulfone blends were investigated. It was shown that a one-to-one blend resulted in a membrane having similar antifouling properties to pure sulfonated polysulfone. Both membranes reject humic matter in the 91–98% range and show a flux decline of 5–30% as a result of surface fouling.     

Optical resolution of (R,S)‐2‐phenyl‐1‐propanol through enantioselective ethycellulose membranes

Enantioselective membrane was prepared using ethyl cellulose (EC) as membrane material. The flux and permselective properties of membrane using aqueous solution of (R,S)‐2‐phenyl‐1‐propanol as feed solution was studied. The employed membrane process was a pressure driven process. All kinds of important conditions including preparation and operation of membranes were investigated in this experimentation. When the membrane was prepared with 18 wt % EC, 20 wt % N,N‐dimethylformamide in casting solution, 13 min evaporation time and 0°C temperature of water bath for the gelation of the membrane, and the operating pressure and feed solution of (R,S)‐2‐phenyl‐1‐propanol were 0.2 MPa and 1.5 mg/mL, respectively, over 90% of enantiomeric excess (e.e.) and 44.2 (mg/m² h) of flux were obtained. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009