Preparation and characterization of modified polysulfone membranes with high hydrophilic property using variation in coagulation bath temperature and addition of surfactant

In this research, novel asymmetric polysulfone (PSF) membranes were prepared from PSF/polyethylene glycol (PEG)/polyoxyethylene sorbitan monolaurate/1‐methyl‐2‐pyrrolidone (NMP) system via immersion precipitation. Pure water was used as gelation media. The variation effect of coagulation bath temperature (CBT) and addition of surfactant on morphology, wettability, and pure water flux (PWF) of the prepared membranes were studied by scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle measuring instrument, and experimental set up. The contact angle measurements demonstrated that hydrophilicity of the PSF membranes was significantly enhanced by small addition of surfactant in the casting solution along with using the lowest level of CBT. Also it was found out that addition of the surfactant in the casting solution along with increasing the CBT incites the formation of the bigger pores on the top surface and results in the formation of membranes with higher thickness and more porous structure in the sublayer. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Effects of coagulation bath temperature on performances of polyethersulfone membranes modified by nanosilver particles in situ reduction

In this work, an in situ reduction method was used to prepare nanosilver‐modified polyethersulfone (PES‐Ag) ultrafiltration membranes by mixing up the reducing agent ethylene glycol and the protective agent polyvinylpyrrolidone to reduce AgNO₃ in the casting solution. The effects of coagulation bath temperature (CBT) on the separation performances, antifouling property, tensile strength, and stability of the nanosilver particles were researched. The results indicated that when the PES‐Ag membranes were prepared in 40°C coagulation bath, the loss rate of nanosilver particles during preparation was minimum, only 18.5%. With the CBT increasing from 20 to 60°C, the water flux of the PES and PES‐Ag membranes increased, whereas the rejection rate decreased. The largest flux reached 471 L·m^?2·h^?1 for PES‐Ag membranes prepared at 60°C and the rejection was over 90%. The results of contact angle and flux recovery ratio showed that PES‐Ag membranes had better hydrophilicity and antifouling property. Furthermore, the PES‐Ag membranes could inhibit Escherichia coli from growing. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Effects of coagulation bath temperature and polyvinylpyrrolidone content on flat sheet asymmetric polyethersulfone membranes

In this study, effects of coagulation bath temperature (CBT) and polyvinylpyrrolidone (PVP K15) concentration as a pore former hydrophilic additive on morphology and performance of asymmetric polyethersulfone (PES) membranes were investigated. The membranes were prepared from a PES/ethanol/NMP system via phase inversion induced by immersion precipitation in a water coagulation bath. The morphology of prepared membranes was studied by scanning electron microscopy (SEM), contact angle measurements, and mechanical property measurements. Permeation performance of the prepared membranes was studied by separation experiments using pure water and bovine serum albumin (BSA) solution as feed. The obtained results indicate that addition of PVP in the casting solution enhances pure water permeation flux and BSA solution permeation flux while reducing protein rejection. Increasing CBT results in macrovoid formation in the membrane structure and increases the membrane permeability and decreases the protein rejection. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Preparation and characterization of nanoporous polysulfone membranes with high hydrophilic property using variation in CBT and addition of tetronic‐1107 surfactant

Asymmetric polysulfone (PSF) membranes were prepared from PSF, Tetronic‐1107, and 1‐methyl‐2‐pyrrolidone (NMP) via immersion precipitation. Pure water was used as the gelation media. The effects of coagulation bath temperature (CBT) (0 and 25°C), and addition of Tetronic‐1107 on the morphology, wettability, and pure water permeation flux (PWF) of the prepared membranes were studied by scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle measurements, and experimental set up. The contact angle measurements demonstrated that the hydrophilicities of the nanoporous PSF membranes were significantly enhanced by addition of a small amount of Tetronic‐1107 surfactant in the casting solution, along with using the lower CBT. It was also found that addition of Tetronic‐1107 in the casting solution along with increasing the CBT from 0 to 25°C incites formation of bigger pores on the top surface and results in formation of membranes with higher thickness and more porous structure in the sublayer. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Properties of polyethersulfone ultrafiltration membranes modified by polyelectrolytes

This study reports on the surface modification of ultrafiltration membranes using the layer-by-layer (LbL) technique. The novelty of this work resides in the LbL assembly of charged polyelectrolytes by electrostatic adsorption directly onto the ultrafiltration membranes without any prior treatment of the surface. Polyethersulfone ultrafiltration membranes have been employed for the deposition of branched poly(ethyleneimine) and poly(sodium 4-styrene sulfonate) to create a thin polyelectrolyte film on their surface. The modified membranes are characterized by their permeability and molecular weight cut-off (MWCO) value. Experiments show that the deposited polyelectrolyte layer causes a decrease in the permeability due to the additional resistance of the layers. However, the MWCO value is shifted meaning a better rejection of the dextran solution is achieved. Thus, the LbL assembly of polyelectrolyte multilayers on the surface of the membrane makes it possible to convert a membrane with open structure to a membrane with denser active layer.     

Photodegradation of imidacloprid insecticide using polyethersulfone membranes modified with iron doped cerium oxide

The widespread accumulation of insecticides in water systems is a growing concern. This study reports efficient photodegradation of imidacloprid (IMD) insecticide using polyethersulfone (PES) membranes modified with iron-doped cerium oxide (Fe-CeO₂). The work focuses on the modification of ultrafiltration polyethersulfone membranes with incremental amounts of Fe-CeO₂ photocatalysts (0.5–2.0 wt.%) using phase inversion method. An increase in Fe-CeO₂ content showed an improvement in surface roughness and porosity of membranes. Pure water flux (PWF) increased from 55.9 L m² h⁻¹ in M0 (PES) to 77.2 (M1, 0.5% Fe-CeO₂-PES), 118.0 (M2, 1% Fe-CeO₂-PES), 128.0 in M3 (1.5 wt.% Fe-CeO₂-PES) and then decreased to 98.5 L m² h⁻¹ in M4 (2 wt.% Fe-CeO₂-PES). This decrease is brought about by the high Fe-CeO₂ content, which minimizes the membranes' surface pores. Fe-CeO₂ photocatalysts are thought to give the membrane both hydrophilic and photocatalytic qualities because of their capacity to absorb light and create radical species that cause the photodegradation of IMD molecules. Consequently, under visible light irradiation, modified membranes demonstrated photocatalytic ability over IMD. Photocatalytic efficiencies of the membranes were found to be 5.2% (M0), 68.9 (M1), 75.8 (M2), 81.8 (M3), and 56.0% (M4), respectively, with M3 membranes showing the highest photocatalytic degradation efficiency and low leaching of metals. The remarkable performance observed by M3 membranes during both water filtration and photocatalytic performance may be an illustration of well dispersed photocatalyst which receives high absorption of light irradiation. Membranes with photocatalytic functionalities are tailored to exploit dual benefits of the membrane filtration and photocatalysis without compromising their original functions. However, maintaining the delicate balance of this phenomenon is still very challenging.     

Properties of polyethersulfone ultrafiltration membranes modified with polyethylene glycols

Polyethersulfone ultrafiltration membranes have been prepared using polyethylene glycols (PEGs) of 400, 1000, and 10,000 gmol, as additive with dimethylacetamide as solvent. Infrared analysis proves that PEG leaves almost completely the surface of the membranes after 24 h of water immersion. Scanning electron microscopy, contact angle, and liquid–liquid displacement porometry have been used to characterize the membrane morphology, surface hydrophilicity and porous structure. The relative flux reduction factor, flux, retention—of PEG (20,000 and 35,000 g/mol) and bovine serum albumin (67,000 g/mol)—and pure water permeability have been measured for the membranes. Results show that the addition of PEG increases slightly hydrophilicity and decreases pore size and narrows the corresponding pore size distribution while thickening the skin layer, in spite of the fast disappearance of the added PEG form the membrane surface. The resulting flux and pure water permeability are higher when middle size PEGs are added but decrease again when very high molecular weight (MW) PEGs are added. Retention decreases initially for increasing MWs of PEG although for very long PEG chains (MW of 10,000 g/mol) retention increases again. After filtration, the membranes with PEG added showed a lower relative flux reduction that decreases for increasing MW of the added PEGs. © 2013 Society of Plastics Engineers. POLYM. ENG. SCI., 54:1211–1221, 2014. © 2013 Society of Plastics Engineers     

季铵化聚醚砜氢氧根离子交换膜的制备及研究

以氯甲基辛基醚(CMOE)为氯甲基化试剂,成功制备了不同取代度的氯甲基化聚醚砜(CMPES),使用三甲胺水溶液将CMPES膜季铵化,制备出季铵化聚醚砜氢氧根离子(QAPESOH)交换膜。对膜的离子交换容量、吸水率、溶胀度以及离子传导率进行测试,结果表明,当QAPESOH膜的氯甲基化程度(DC)在23%～51%时,即使温度升高到60℃,膜都具有良好的吸水率和适当的溶胀度。特别是DC为51%的膜,其氢氧根传导率在20℃时可以达到15.6mS/cm,并且具有良好的机械稳定性,说明QAPESOH膜在氢氧根离子交换膜燃料电池方面有很好的应用前景。     

Fouling control in sugarcane juice ultrafiltration with surface modified polysulfone and polyethersulfone membranes

Commercial 50 and 100 kD polyethersulfone (PES) and polysulfone (PS) ultrafiltration membranes were surface modified by UV photografting of poly(ethylene glycol) methacrylate (PEGMA) monomer. The modified membranes were characterized by the degree of grafting, water flux and molecular weight cutoff (MWCO) rating. The flux and fouling of the modified and unmodified membranes were examined with sugarcane juice and its polysaccharide fraction. Under the conditions of this study, the modified membranes displayed a low degree of grafting (26-36 μg/cm²), which was independent of the UV exposure duration; however, both membrane water flux and MWCO rating were affected by the irradiation time. In the best case, the modified membranes exhibited lower fouling with sugarcane juice; furthermore, the propensity to foul also decreased. More significantly, juice flux recovery was almost complete for successive UF-cleaning cycles.     

Preparation and performance of the novel PVDF ultrafiltration membranes blending with PVA modified SiO2 hydrophilic nanoparticles

In this study, PVA‐SiO₂ was synthesized by modifying silica (SiO₂) with polyvinyl alcohol (PVA), then a novel polyvinylidene fluoride (PVDF) ultrafiltration (UF) membrane was prepared by incorporating the prepared PVA‐SiO₂ into membrane matrix using the non‐solvent induced phase separation (NIPS) method. The effects of PVA‐SiO₂ particle on the properties of the PVDF membrane were systematically studied by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT‐IR), surface pore size, porosity, and water contact angle. The results indicated that with the addition of PVA‐SiO₂ particles in the PVDF UF membranes, membrane mean pore size increased from 80.06 to 126.00 nm, porosity improved from 77.4% to 89.1%, and water contact angle decreased from 75.61° to 63.10°. Furthermore, ultrafiltration experiments were conducted in terms of pure water flux, bovine serum albumin (BSA) rejection, and anti‐fouling performance. It indicated that with the addition of PVA‐SiO₂ particles, pure water flux increased from 70 to 126 L/m² h, BSA rejection increased from 67% to 86%, flux recovery ratio increased from 60% to 96%, total fouling ratio decreased from 50% to 18.7%, and irreversible fouling ratio decreased from 40% to 4%. Membrane anti‐fouling property was improved, and it can be expected that this work may provide some references to the improvement of the anti‐fouling performance of the PVDF ultrafiltration membrane. POLYM. ENG. SCI., 59:E412–E421, 2019. © 2018 Society of Plastics Engineers     

Synthesis and characterization of polyethersulfone membranes

Phase inversion method was used to prepare polyethersulfone (PES) ultrafiltration (UF) membranes. Polyethylene glycol (PEG); N, N-dimethyl formamide (DMF) and water were utilized as pore-forming additive, solvent and non-solvent, respectively. Effects of PES and PEG concentrations in the casting solution, PEG molecular weight (MW) and coagulation bath temperature (CBT) on morphology of the prepared membranes were investigated. Taguchi experimental design was applied to run a minimum number of experiments. 18 membranes were synthesized and their permeation and rejection properties to pure water and human serum albumin (HSA) solution were studied. It was found out that increasing PEG concentration, PEG MW and CBT, accelerates diffusional exchange rate of solvent (DMF) and non-solvent (water) and consequently facilitates formation of macrovoids in the membrane structure. The results showed that, increasing PES concentration, however, slows down the demixing process. This prevents instantaneous growth of nucleuses in the membrane structure. Hence, a large number of small nucleuses are created and distributed throughout the polymer film and denser membranes are synthesized. A trade-off between water permeation and HSA rejection was involved, with membranes having higher water permeation exhibited lower HSA rejection, and vice versa. Hence, optimizing preparation variables to achieve high pure water permeation flux along with reasonable HSA rejection was inevitable. Analysis of variance (ANOVA) showed that all parameters have significant effects on the response (water flux and HSA rejection). However, CBT and PES concentration were more influential factors than PEG concentration and MW on the responses.     

Developing homogeneous ion exchange membranes derived from sulfonated polyethersulfone/N-phthaloyl-chitosan for improved hydrophilic and controllable porosity

Ion exchange membranes (IEMs) composed of sulfonated poly (ether sulfone) (SPES) and N-phthaloyl chitosan (NPHCs) were synthesized. NPHCs was employed in membrane fabrication to improve the porosity and hydrophilicity of membranes. The effect of blend ratio of sulfonation (DS) and NPHCs content on physico-chemical characteristics of home-made membranes was investigated. The morphology of prepared membranes was investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD) and scanning electron microscopy (SEM). SEM images revealed the formation of a more porous membrane structure and smoother surface. The electrochemical and physical properties of CEMs were characterized comprising water content, contact angle, ion exchange capacity (IEC) and thermal stability. Membrane water content, surface hydrophilicity and IEC were enhanced with increase of DS and NPHCs blend ratios in casting solution. Furthermore, the diffusion coefficient was also improved slightly with increase of DS and NPHCs blend ratios in prepared membranes. Membrane potential, permselectivity, transport number and areal membrane resistance all showed decreasing trends by the increase in NPHCs blend ratio in casting solution. These results indicated that the prepared membrane has good prospective and great potential for desalination in electrodialysis applications.     

Surface characterization and Remazol Red adsorption by asymmetric polyethersulfone membranes modified by polyelectrolyte complexes

Polyethersulfone (PES) membranes containing 4-fluorophenyl sulfone-terminated poly(diallylpiperidinium hexafluorophosphate)-sulfonated poly(ethylene terephthalate) polyelectrolyte complexes (PECs) were obtained via phase inversion using three different methods that enabled the complexation of polyelectrolytes (PELs) to occur before, after, and during membrane formation. Atomic force microscopy-infrared spectroscopy analysis revealed varying concentrations of the polyanion depending on the preparation method and confirmed the presence of PECs in the membranes, highlighting an increase in surface roughness. Zeta potential measurements demonstrated positive surface charges for the membrane comprising PES and the polycation. The reduction in zeta potential in PEC membranes corresponded with the neutralization of positive groups by sulfonated poly(ethylene terephthalate. Scanning electron microscopy micrographs depicted surface imperfections in PEC membranes, emphasizing the influence of PECs on membrane surfaces. The water contact angle decreased, indicating increased hydrophilicity in PEC membranes. Additionally, dye adsorption results showcased significant adsorption, with the membranes absorbing at least 60% of Remazol Red from an aqueous solution. Notably, the Blend membrane outperformed others, exhibiting an exceptional adsorption rate exceeding 92%.     

The effects of spinning temperature on morphologies and properties of polyethersulfone hollow fiber membranes

Polyethersulfone (PES) hollow fiber membranes were prepared by traditional dry‐wet spinning technique. Scanning electronic microscopy (SEM) was used to characterize membrane morphologies, and the membrane properties were evaluated via bubble point measurements and ultrafiltration experiments. The effects of spinning temperature on the morphologies and properties of PES fibers were investigated in detail. At a high spinning temperature, the obtained membrane structure consisting of a thin skin‐layer and loose sponge‐like sublayer endows PES membrane with not only good permeability, but also high solute rejection. Based on the determination of ternary phase diagrams and light transmittance curves, the relationship of membrane morphologies with thermodynamics and precipitation kinetics of membrane‐forming system was discussed. It was concluded that the morphologies and properties of PES hollow fiber membrane could be conveniently tuned by the adjustment of the spinning temperature and air gap. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

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     

Influence of coagulation bath on morphology of cellulose membranes prepared by NMMO method

To control the morphology of cellulose membranes used for separation, they were prepared by the NMMO method using water, methanol, ethanol and their binary solution as coagulation baths. Morphologies of the surface and cross section of dry membranes were observed. The pore structure parameters of wet membranes were determined. By comparison, the process and mechanism of pore formation in dry membranes were suggested, and the relativity of cellulose crystal size to average pore diameter in wet membranes and their influences were discussed. The results show that the morphology of dry membranes is clearly varied with coagulation baths, while the porosity of wet membranes is almost constant. Porous structures can appear in the compact region of dry membranes due to swelling from water. These pores have a virtual effect on the average pore diameter of wet membranes. By changing the composition of coagulation baths, the microstructure of cellulose membranes in a dry or wet environment can be adjusted separately. __________ Translated from Journal of Chemical Engineering of Chinese Universities, 2007, 21(3): 398–403 [译自: 高校化学工程学报]     

Influence of coagulation bath on morphology of cellulose membranes prepared by NMMO method

To control the morphology of cellulose membranes used for separation, they were prepared by the NMMO method using water, methanol, ethanol and their binary solution as coagulation baths. Morphologies of the surface and cross section of dry membranes were observed. The pore structure parameters of wet membranes were determined. By comparison, the process and mechanism of pore formation in dry membranes were suggested, and the relativity of cellulose crystal size to average pore diameter in wet membranes and their influences were discussed. The results show that the morphology of dry membranes is clearly varied with coagulation baths, while the porosity of wet membranes is almost constant. Porous structures can appear in the compact region of dry membranes due to swelling from water. These pores have a virtual effect on the average pore diameter of wet membranes. By changing the composition of coagulation baths, the microstructure of cellulose membranes in a dry or wet environment can be adjusted separately.     

Silver-filled polyethersulfone membranes for antibacterial applications — Effect of PVP and TAP addition on silver dispersion

Silver-filled asymmetric polyethersulfone (PES) membranes were prepared by a simple phase inversion technique. The effects of polyvinylpyrrolidone (PVP) and 2, 4, 6-triaminopyrimidine (TAP) on the surface properties of the silver-filled asymmetric membrane were investigated for antibacterial application. The dispersion of silver nanoparticles (Ag) and silver content on membrane surface were characterized using field emission scanning electron microscope (FESEM) and energy dispersive spectrometer (EDS), respectively. Results showed that smaller silver particles were formed in PES membranes when PVP and TAP were added during dope preparation. Using inductively coupled plasma mass spectrometry (ICP-MS), it is found that silver leaching has been significantly reduced up to 57% and 63% upon the addition of PVP and TAP respectively. The improved silver dispersion on membrane surfaces was able to enhance the antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as evidenced by larger inhibition ring in agar diffusion method. The filtration of E. coli suspension (optical density = 0.31 at λ = 600 nm) carried out on prepared membranes proved that PES-AgNO₃ with TAP as dispersant appeared to inhibit almost 100% bacterial growth in rich medium. Hence, overall results showed the potential of PES-AgNO₃ with TAP to be used for antibacterial applications especially in water treatment.     

亲水改性高岭土/聚氨酯乳液的制备及性能表征

钛酸酯偶联剂对水洗高岭土进行亲水改性,通过机械共混法制备了亲水改性高岭土/水性聚氨酯复合材料,研究了复合材料的力学性能、耐热性能。结果表明,当改性高岭土质量分数2.0%时,复合材料的拉伸强度为24.4 MPa,比聚氨酯增加53.1%,断裂伸长率达492%,增加9.6%,实现了复合材料的增韧增强,同时热稳定性也有所提高。     

聚砜/改性碳纳米管复合膜的制备及亲水性能

利用浸没沉淀相转化法,以聚砜(PSF)为膜材料,羧基化碳纳米管(MWCNTs-COOH)为添加剂,聚乙烯吡咯烷酮(PVP)为致孔剂,N,N-二甲基乙酰胺(DMAc)为溶剂,制备了聚砜/多壁碳纳米管复合膜,系统研究了制备复合膜时碳纳米管的添加量、预挥发时间以及凝固浴组成对其结构和性能的影响。实验结果表明,添加MWCNTs-COOH后,复合膜的亲水性能和抗污性能显著提高,同时复合膜的力学性能也明显增强。复合膜的 SEM 照片显示,随预挥发时间的延长和凝固浴中DMAc 质量分数的增加,复合膜断面由指状孔结构向海绵状孔结构过渡;复合膜的水通量下降,截留率上升。