Bovine Serum Albumin Rejection Research Articles

Graphene oxide/chitosan doped polysulfone membrane for the treatment of industrial wastewater

Rapid urbanization and industrialization have created tremendous stress on fresh water sources. Moreover, discharge of industrial wastewater has left public health and environment under high potential risks. In this paper, chitosan-functionalized graphene oxide (GO-CH) was synthesized and incorporated into polysulfone (Psf) ultrafiltration membranes. The concentration of the nanocomposite and the ratio of GO to CH in the nanocomposite were varied to produce different GO-CH doped polysulfone membranes. The effect of GO-CH addition on the morphology and membrane performance was studied through water contact angle, scanning electron microscopy, atomic force microscopy, porosity, pore size, and permeation measurements as well as rejection and antifouling tests, while produced GO-CH nanocomposite was characterized using FTIR and XRD analyses. The GO-CH/Psf membrane exhibited higher water flux, bovine serum albumin (BSA) rejection rate, and water flux recovery ratio, and lower BSA solution flux attenuation rate than pristine Psf membrane. GO-CH/Psf membrane containing 0.085 wt% nanocomposite with GO to CH ratio of 1 to 0.01 had an improved permeate flux of 136%. Maintaining the same GO-CH composition of 0.085 wt% and changing GO to CH ratio to 1:1 resulted in better hydrophilicity (contact angle 68°) and increased reversible fouling from 23 to 33%. The best membrane was further tested with real industrial wastewater obtained from a GTL plant in Qatar showed 28% improvement in COD removal.

Magnetic‐field‐inducedFe3O4@CNTsdispersion in the separation layer to improve the performance of composite ultrafiltration membrane

AbstractIt is of great significance to regulate carbon nanotubes (CNTs) dispersed in the separation layer of membranes to improve the properties of membranes. In this work, ferric oxides coated carbon nanotubes (Fe3O4@CNTs) are prepared by solvothermal method, and then are added to the casting solution to prepare Fe3O4@CNTs/poly(ethersulfone)/sulfonated polysulfone composite ultrafiltration membranes. The result shows that Fe3O4@CNTs migrate to the separation layer of membranes under the induction of a low‐intensity magnetic field. The surface and overall porosity of the membranes increase and the surface roughness of the membranes decreases. The contact angle of composite ultrafiltration membranes decreases from 78.0° to 60.1°, indicating an improvement of hydrophilicity. The pure water permeance of the composite ultrafiltration membranes increases from 240.1 to 524.7 L m−2 h−1while retaining a high bovine serum albumin rejection (>96.8%). Moreover, the antifouling property of the composite ultrafiltration membranes is significantly improved, and the flux recovery ratio increased from 56.2% to 80.9%.

Antibacterial PES/Vancomycin ultrafiltration membranes with enhanced water flux and low BSA rejection

AbstractPolyethersulfone (PES) blended with glycopeptide Vancomycin was fabricated via phase inversion method. The fabricated membranes were characterized by scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), contact angle (CA) and optical profilometry. The PES/Vancomycin membranes showed a notable increase in hydrophilicity, porosity, pore size, antibacterial activity and water flux in comparison with pristine membranes. The changes are due to the hydrophilic nature of Vancomycin molecules and ability to form hydrogen bond quickly. The surface hydrophilicity of PES/Vancomycin membranes decreased up to 48° with increase in surface roughness (Ra), that is, 0.347 μm, thus increasing the water flux of PES/Vancomycin membranes up to 340 L/m2. h. The bovine serum albumin (BSA) rejection decreases, that is, pristine 70.9% to PES/Vancomycin 26% and BSA flux increases at constant ionic strength (0.1) and above the isoelectric point (IEP) of the BSA. Under these conditions, electrostatic interactions are expected to be minimum between protein and the membrane surfaces.

Fabrication and characterization of dual-layer hollow fiber membranes incorporating poly(citric acid) grafted GO with enhanced antifouling property for water treatment

ABSTRACT Membrane fouling which occurs during filtration process is a perennial issue and could lead to reduced separation efficiency. In this work, poly(citric acid) grafted graphene oxide (PGO) was respectively incorporated into matrix of single-layer hollow fiber (SLHF) and duallayer hollow fiber (DLHF) membranes, aiming to improve membrane antifouling properties during water treatment. Different loading of PGO ranging from 0 to 1 wt% was first introduced into the SLHF in order to identify the best PGO loading for the DLHF preparation with its outer layer modified by nanomaterials. The findings showed that at the optimized PGO loading of 0.7 wt%, the resultant SLHF membrane could achieve both higher water permeability and bovine serum albumin rejection compared to the neat SLHF membrane. This is owing to the improved surface hydrophilicity and increased structural porosity upon the incorporation of optimized PGO loading. When 0.7 wt% PGO was introduced only to the outer layer of DLHF, the cross-sectional matrix of the membrane was altered, forming microvoids and spongy-like structure (more porous). Nevertheless, the BSA rejection of the membrane was improved to 97.7% owing to the presence of inner selectivity layer that was produced from different dope solution (without PGO addition). The DLHF membrane also demonstrated significantly higher antifouling properties compared to the neat SLHF membrane. Its flux recovery rate is 85%, i.e., 37% better than that of neat membrane. By incorporating hydrophilic PGO into the membrane, the interaction of the hydrophobic foulants with the membrane surface is greatly reduced.

Ag@BiOBr/PVDF photocatalytic membrane for remarkable BSA anti-fouling performance and insight of mechanism

Membrane technologies offer great potential in desalination and wastewater treatment. However, the serious issue of membrane fouling results in the unsatisfactory sustainability and reusability for treating wastewater containing high level of organic foulants. In this work, a photocatalytic membrane reactor system combining Ag@BiOBr photocatalyst and polyvinylidene fluoride (PVDF) ultrafiltration with remarkable anti-fouling property was constructed. The integrated Ag@BiOBr/PVDF photocatalytic ultrafiltration membranes were prepared by blending Ag@BiOBr nanoparticles (NPs) into PVDF membrane via phase inversion method. The membrane separation performance and fouling resistance were studied in a cross-flow ultrafiltration system using bovine serum albumin (BSA) as the model foulants. Compared with the pristine PVDF membrane, the hydrophilicity and surface smoothness of composite membranes were promoted by photocatalyst-incorporation, the Ag@BiOBr/PVDF membrane with the optimal Ag@BiOBr blending content of 2.0 wt% achieved both enhanced water flux and higher BSA rejection efficiency. More importantly, the mechanism of anti-fouling and self-cleaning performances were further studied, the photocatalysis process based on Ag@BiOBr/PVDF membrane effectively decomposed the BSA foulant into broken protein with induced change of carbonyl, ionic bond and hydrogen bond contents in BSA foulants via the active radicals, weakened the intermolecular force of BSA foulants to prevent membrane pore blockage. Meanwhile, the broken protein peptide chains with more negative charges could result in the strength of electrostatic repulsive forces between BSA molecules and membrane. As a result, the BSA foulant could be stably removed in the Ag@BiOBr/PVDF photocatalytic ultrafiltration system under visible light irradiation, achieving the excellent anti-fouling performance by preventing the membrane pore blockage and foulant adhesion. We believe the Ag@BiOBr/PVDF photocatalytic membrane presented in this study will be one example among many photocatalyst-membrane combinations that can be further pursued for organic pollutants removal. In particular, we expect the theoretical support can present a great opportunity to design novel photocatalytic membranes with sustainable anti-fouling performance.

In Situ Incorporation of TiO2@Graphene Oxide (GO) Nanosheets in Polyacrylonitrile (PAN)-Based Membranes Matrix for Ultrafast Protein Separation.

Organic polymeric ultrafiltration (UF) membranes have been widely used in protein separation due to their advantages of high flux and simple manufacturing process. However, due to the hydrophobic nature of the polymer, pure polymeric UF membranes need to be modified or hybrid to increase their flux and anti-fouling performance. In this work, tetrabutyl titanate (TBT) and graphene oxide (GO) were simultaneously added to the polyacrylonitrile (PAN) casting solution to prepare a TiO2@GO/PAN hybrid ultrafiltration membrane using a non-solvent induced phase separation (NIPS). During the phase separation process, TBT underwent a sol-gel reaction to generate hydrophilic TiO2 nanoparticles in situ. Some of the generated TiO2 nanoparticles reacted with the GO through a chelation interaction to form TiO2@GO nanocomposites. The resulting TiO2@GO nanocomposites had higher hydrophilicity than the GO. They could selectively segregate towards the membrane surface and pore walls through the solvent and non-solvent exchange during the NIPS, significantly improving the membrane's hydrophilicity. The remaining TiO2 nanoparticles were segregated from the membrane matrix to increase the membrane's porosity. Furthermore, the interaction between the GO and TiO2 also restricted the excessive segregation of the TiO2 nanoparticles and reduced their losing. The resulting TiO2@GO/PAN membrane had a water flux of 1487.6 L·m-2·h-1 and a bovine serum albumin (BSA) rejection rate of 99.5%, which were much higher than those of the currently available UF membranes. It also exhibited excellent anti-protein fouling performance. Therefore, the prepared TiO2@GO/PAN membrane has important practical applications in the field of protein separation.

Enhancing antifouling characteristics and performance against protein macromolecule foulant on PVDF membrane ultrafiltration with eco-friendly Arabic gum additive

This study investigated the effects of Arabic gum (AG) on the separation performance of polyvinylidene fluoride (PVDF) membranes. The membrane properties were characterized using scanning electron microscope energy dispersive X-ray (SEM–EDX), Fourier transforms infrared (FTIR), tensile strength tester, and contact angle. Results showed that incorporating AG from 0.5 wt% to 1.5 wt% into PVDF membrane could increase pure water flux from 47.46 L/m2 h to 66.04 L/m2 h and porosity from 53% to 58%. Moreover, the highest flux recovery was obtained by PVDF/AG-1.5 membrane, revealing the improvement in fouling resistance against bovine serum albumin (BSA). However, the addition of AG from 0.5 wt% to 1.5 wt% did not affect to increase of membrane mechanical strength and the efficiency of the membranes for BSA rejection. SEM, XRD and FTIR analyses confirmed the successful incorporation of AG, which improved membrane surface hydrophilicity compared to the pristine PVDF membrane. Overall, the obtained result showed that incorporating AG could attain synergy benefits in enhancing the membrane properties and performance.

Preparation and Characterization of PVDF-TiO2 Mixed-Matrix Membrane with PVP and PEG as Pore-Forming Agents for BSA Rejection.

Polymeric membranes offer straightforward modification methods that make industry scaling affordable and easy; however, these materials are hydrophobic, prone to fouling, and vulnerable to extreme operating conditions. Various attempts were made in this study to fix the challenges in using polymeric membranes and create mixed-matrix membrane (MMMs) with improved properties and hydrophilicity by adding titanium dioxide (TiO2) and pore-forming agents to hydrophobic polyvinylidene fluoride (PVDF). The PVDF mixed-matrix ultrafiltration membranes in this study were made using the non-solvent phase inversion approach which is a simple and effective method for increasing the hydrophilic nature of membranes. Polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG) as pore-forming chemicals were created. Pure water flux, BSA flux, and BSA rejection were calculated to evaluate the mixed-matrix membrane's efficiency. Bovine serum albumin (BSA) solution was employed in this study to examine the protein rejection ability. Increases in hydrophilicity, viscosity, and flux in pure water and BSA solution were achieved using PVP and PEG additives. The PVDF membrane's hydrophilicity was raised with the addition of TiO2, showing an increased contact angle to 71°. The results show that the PVDF-PVP-TiO2 membrane achieved its optimum water flux of 97 L/(m2h) while the PVDF-PEG-TiO2 membrane rejected BSA at a rate greater than 97%. The findings demonstrate that use of a support or additive improved filtration performance compared to a pristine polymeric membrane by increasing its hydrophilicity.

Fabrication and characterization of cellulose acetate ultrafiltration membrane and its application for efficient bovine serum albumin separation

AbstractTo solve the easy contamination problem of ultrafiltration membranes during protein separation, a series of cellulose acetate (CA) ultrafiltration membranes with different pore morphology and structure were successfully prepared by combining solution casting, non‐solvent‐induced phase inversion, and pore‐forming agent leached out technologies. The effects of molecule weight and the content of porogen polyethylene glycol (PEG) on the pore morphology, chemical composition, and wettability of the CA ultrafiltration membrane were systematically studied. The feed permeability, bovine serum albumin rejection, and anti‐fouling ability were also investigated. The results showed that the CA10k membrane has the highest pure water flux of 877.5 L/m2h.bar, largest bovine serum albumin (BSA) rejection of 96.5% and flux recovery rate of 90.9% when the PEG molecule weight and content are 10 kDa and 10 wt%. Those results showed that the CA ultrafiltration membranes have great application prospects in the BSA separation area.

Fabrication of cellulose nanocrystal (CNC) from waste paper for developing antifouling and high-performance polyvinylidene fluoride (PVDF) membrane for water purification

Waste papers are used as a source of raw material to fabricate cellulose nanocrystals (CNCs), a highly valued product with a high degree of crystallinity. Rod-shaped CNCs with an average diameter of 53 ± 9 nm and an average length of 234 ± 42 nm were obtained with a crystallinity of around 78%. Polyvinylidene fluoride (PVDF) thin composite membrane was developed by adding CNCs into the PVDF matrix in different amounts (0, 0.5, 1, 1.5, 2, 3 wt%). Porous finger-like structures in the membrane increased with an increase in CNC content. The FTIR measurement and high-resolution FESEM image of the membranes verified the presence of CNCs in the composite membranes. 48% high pure water flux (PWF) was obtained for PVDF/CNC as compared to pristine PVDF membrane with the addition of 3% CNCs at a pressure of 1 kg−1cm−2. Water contact angle (WCA) also decreased from 85° to 69° with increasing the wt% of CNCs in the dope solution, which signifies improved hydrophilicity. Further, the PVDF/CNCs membrane showed a high bovine serum albumin (BSA) rejection of 93% and a flux recovery ratio (FRR) of 76.76 %, whereas the pristine PVDF membrane showed BSA rejection of 70.86% and a FRR of 40.82 %, respectively.

Enhanced Antifouling in Flat-Sheet Polyphenylsulfone Membranes Incorporating Graphene Oxide-Tungsten Oxide for Ultrafiltration Applications.

In this study tungsten oxide and graphene oxide (GO-WO2.89) were successfully combined using the ultra-sonication method and embedded with polyphenylsulfone (PPSU) to prepare novel low-fouling membranes for ultrafiltration applications. The properties of the modified membranes and performance were investigated using Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), contact angle (CA), water permeation flux, and bovine serum albumin (BSA) rejection. It was found that the modified PPSU membrane fabricated from 0.1 wt.% of GO-WO2.89 possessed the best characteristics, with a 40.82° contact angle and 92.94% porosity. The permeation flux of the best membrane was the highest. The pure water permeation flux of the best membrane showcased 636.01 L·m-2·h-1 with 82.86% BSA rejection. Moreover, the membranes (MR-2 and MR-P2) manifested a higher flux recovery ratio (FRR %) of 92.66 and 87.06%, respectively, and were less prone to BSA solution fouling. The antibacterial performance of the GO-WO2.89 composite was very positive with three different concentrations, observed via the bacteria count method. These results significantly overtake those observed by neat PPSU membranes and offer a promising potential of GO-WO2.89 on activity membrane performance.

Electrostatic Repulsive Features of Free-Standing Titanium Dioxide Nanotube-Based Membranes in Biofiltration Applications.

This study presents the electrostatic repulsive features of electrochemically fabricated titanium dioxide nanotube (NT)-based membranes with different surface nanomorphologies in cross-flow biofiltration applications while maintaining a creatinine clearance above 90%. Although membranes exhibit antifouling behavior, their blood protein rejection can still be improved. Due to the electrostatically negative charge of the hexafluorotitanate moiety, the fabricated biocompatible, superhydrophilic, free-standing, and amorphous ceramic nanomembranes showed that about 20% of negatively charged 66 kDa blood albumin was rejected by the membrane with ∼100 nm pores. As the nanomorphology of the membrane was shifted from NTs to nanowires by varying fabrication parameters, pure water flux and bovine serum albumin (BSA) rejection performance were reduced, and the membrane did not lose its antifouling behavior. Herein, nanomembranes with different surface nanomorphologies were fabricated by a multi-step anodic oxidation process and characterized by scanning electron microscopy, atomic force microscopy, water contact angle analysis, X-ray diffraction, and energy-dispersive X-ray spectroscopy. The membrane performance of samples was measured in 3D printed polyethylene terephthalate glycol flow cells replicating implantable artificial kidney models to determine their blood toxin removal and protein loss features. In collected urine mimicking samples, creatinine clearances and BSA rejections were measured by the spectrophotometric Jaffe method and high-performance liquid chromatography.

Fabrication of dialysis membrane from cotton Giza 86 cellulose di-acetate prepared using Ac2O and NiCl2 as a new catalyst

This attempt has been made to synthesize the cellulose di-acetate in a solvent-free acetylation system of cotton Giza 86 cellulose with Ac2O (200 and 300 ml) in the presence of NiCl2.6HO (1.0, 1.5 and 2.0 g) as an effectively available and new catalyst by the conventional reflux and microwave irradiation methods. This study also illustrates the preparation of a dialysis membrane made from a cellulose di-acetate–dichloromethane-methanol-polyethylene glycol (MW: 200) casting solution. The microwave irradiation method for the synthesis of cellulose di-acetate showed excellent yields and short reaction time, which is an important feature of this method. The impact of the two methods on the cellulose di-acetate formation and its used in the dialysis membrane formulations was studied. The experimental degree of substitution of the prepared cellulose di-acetate values (DS = 2.00–2.7) showed an agreement with the calculated values by FTIR and 1H-NMR analysis methods. The formation of cellulose di-acetate with percentage yields varied from 62.85 to 89.85%. The applicability of the prepared membrane in dialysis operation was evaluated in terms of urea clearance, rejection of Bovine Serum Albumin (BSA) and flux of pure water. Characterization of cellulose di-acetate was achieved through 1H-NMR, FTIR, TGA, and BET analyses. The CA-PEG blend membrane was examined by contact angle measurement, porosity, and water uptake of the membrane. The cellulose acetate membrane surface morphology was determined using SEM. It is observable that the fabricated CA-PEG blend membrane from synthesized cellulose di-acetate by using Nickel chloride as a catalyst is showing remarkable rejection of BSA and urea clearance up to 100 and 67.2%, respectively. The present work is promising and applicable in dialysis membranes.

Tethering hydrophilic macromolecules onto inorganic nanoparticles via RAFT toward biocompatible polyethersulfone membrane

Polyethersulfone (PES) polymers are useful for a variety of membranes' bio-related applications. However, due to its failure to satisfy certain performance and biocompatibility standards, PES requires further surface modification. Herein, we report a facile and flexible method of PES membrane modification by combining the synthesis of silicon oxide nanoparticles grafted with polyvinylpyrrolidone (PVP) as hydrophilic macromolecules via reversible addition fragmentation chain-transfer polymerization (RAFT) and aminated polyethersulfone. The blending of polyethersulfone-modified membranes with SiO2@PVP and aminated polyethersulfone results in a robust, hydrophilic, and biocompatible surface. This research work uniquely uses this strategy to stabilize the existence of the hydrophilic modifiers (SiO2@PVP and aminated polyethersulfone) within the membrane matrix. Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) are used to analyze the prepared polymer brush and the modified membranes. The modified membranes demonstrate high pure water flux at 345 ​L ​m−2 ​h−1 and bovine serum albumin (BSA) rejection at 98 ​%. The prepared membranes also show favorable hydrophilicity with a contact angle of 46.8° compared with pristine polyethersulfone at 79°. Furthermore, the modified membranes demonstrate an acceptable degree of blood biocompatibility according to partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT), and fibrinogen (FIB) concentration analysis. Based on inductively coupled plasma optical emission spectroscopy (ICP-OES), the silicon nanoparticle leaching in permeate is in a safe range. Accordingly, the modified polyethersulfone membrane is safe and suitable for hemodialysis and bio-related applications.

Preparation of a cyclodextrin metal-organic framework (CD-MOF) membrane for chiral separation

Due to their unique properties, the efficient separation of racemic mixtures remains a great challenge. Recently, membrane separation has been demonstrated as a promising chiral separation technique with the advantages of continuous operation, high throughput, and cost effectiveness. In this work, a cyclodextrin-metal-organic framework (CD-MOF) was prepared and then composited with polyvinylidene fluoride (PVDF) polymer by the phase inversion via immersion precipitation method to form a CD-MOF/PVDF composite membrane for chiral amino acid separation for the first time. The composite membranes prepared under different conditions were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) thermogravimetric analysis (TGA)and differential scanning calorimetry (DSC). The effects of preparation conditions including CD-MOF load, polymer concentration, and casting solution temperature on the hydrophilicity, water flux, bovine serum albumin (BSA) rejection and chiral separation performance of the membrane were investigated. It is found that the composite membrane (V-5%−12) prepared with the CD-MOF load of 5%, polymer concentration of 12%, and casting solution of 70 ℃ shows the best performance with the water flux of 466.4 L/m2∙h, BSA rejection rate of 24.3% and stable 100% separation efficiency for phenylalanine (Phe) enantiomers for 4 h. The interaction energies between the CD-MOF and D-Phe and L-Phe were calculated using the Gaussian 09 program package and the chiral separation mechanism of the composite membrane was proposed at the molecular level. Our work demonstrates great development potentials of the CD-MOF/PVDF composite membrane in the chiral separation of drugs.

Fabrication of Polyarylate-Based Porous Membranes from Nonsolvent-Induced Phase Separation Process and Related Permeability and Filterability Characterizations

The stability demand of polymeric membrane separation systems used in harsh environments, including high temperature, high pressure, extreme acid, and high salinity, makes the role of polyarylate (PAR) porous membranes more and more crucial. Herein, the PAR ultrafiltration membrane is fabricated from the nonsolvent-induced phase separation (NIPS) method in a simple, high-efficiency way. In order to study the evolution mechanism of cross-sectional pore morphologies during the NIPS process, different coagulation conditions, including the PAR concentration in casting solution, the coagulation temperature, and the addition of different hydrophilic additives (PEG400, PEG4000, PEG20000, and PVP), are applied. Next, the morphologies and membrane performances of various PAR membranes are analyzed by scanning electron microscopy, porosity measurement, N2 isotherm adsorption–desorption measurement, water flux measurement, bovine serum albumin (BSA) separation measurement, and mechanical test. Based on these measurements, the formation rule of different pore morphologies in the cross section of PAR membrane was clarified, and the effects of different cross-sectional morphologies on the permeability, filterability, and mechanical properties of the resultant membranes are pointed out. The viscosity effect from a higher PAR concentration and a higher hydrophilic additive concentration in a casting solution can delay the formation of the outer layer and limit the nucleation growth process of the nonsolvent, then allowing the formation of near-surface sponge-like pores and fewer inner macropores. Moreover, not only the increase of the bath temperature but also the strengthening hydrophilicity of the casting solution can accelerate the double-diffusion rate and the growth process of nuclei, thereby promoting the formation of near-surface finger-like pores and more inner macropores. Combined with the enhancement of membrane hydrophilicity, these pores as channels can accelerate the passage of water through the PAR membrane. For the PAR16–PVP10-30 membrane, not only a 120 L·m–2·h–1·bar–1 of water flux but also a close to 100% of BSA rejection ratio is obtained. Although the formation of near-surface sponge-like pores and fewer inner macropores deteriorate the membrane’s permeability, the high BSA rejection ratio and the improved mechanical property can be maintained. Finally, the optimization component of the casting solution for fabricating a PAR ultrafiltration membrane with enough permeability, high selectivity, and suitable mechanical property adds 10 wt % PVP in the solution of 16 wt % PAR, ensuring the solid hydrophilic effect and moderate viscosity effect.

Modified emulsion polyvinyl chloride membranes for enhanced antifouling and dye separation properties by introducing tungsten disulfide (WS2) nanosheets

In this study, the fabrication and modification of emulsion polyvinyl chloride (EPVC) membranes were studied using tungsten disulfide (WS2) nanosheets. The layered WS2 nanosheets were synthesized, characterized, and applied in the modification of EPVC membranes. The nonsolvent induced phase inversion method was utilized to fabricate new membranes by introducing the WS2 nanosheets into the polymeric solutions with different percentages. The performance of the fabricated membranes was characterized and evaluated using scanning electron microscopy, atomic force microscopy, attenuated total reflection-Fourier transform infrared, mean pore radius, porosity, contact angle analyses, pure water flux, fouling parameters, rejection tests for bovine serum albumin (BSA) and two dyes, and long-term and reusability tests. The results indicated that the use of WS2 nanosheets in the membrane structure up to the optimum value (1 wt%) increased the water flux and improved the antifouling properties. The pure water flux enhanced from 56.4 L/m2.h in the bare membrane to 191.2 L/m2.h in the 1 wt% WS2/EPVC membrane. In addition, the flux recovery ratio parameter increased from 64.7% to 83.5%. dye rejection rates of 94.7% and 97.8% were obtained for Reactive Red 195 and Reactive Green 19, respectively. Reusability tests for the 1 wt% WS2/EPVC membrane indicated a slight flux drop and negligible BSA rejection changes. Long-term tests showed very high stability in dye rejection and a negligible flux drop.

Robust and highly hydrophilic ultrafiltration membrane with multi-branched cellulose nanocrystals for permeability-selectivity anti-trade-off property

To overcome challenges associated with the “trade-off” effect and membrane fouling, the high-performance ultrafiltration membranes were prepared by blended multi-branched nanocellulose (Multi CNC) into polyethersulfone (PES) matrix using non-solvent induced phase separation (NIPS) technology. The as-prepared composite ultrafiltration membranes have high hydrophilicity, thicker skin layer and lower negative charge due to the abundant polar groups of carboxyl (COOH) in Multi CNC. As the results, the water flux and Bovine serum albumin (BSA) rejection of the composite membranes with 1 wt% Multi CNC reached to 961.65 L/m2·h and 96.4 %, while the flux and rejection of the original PES membrane was only 702.04 L/m2·h and 86.2 % respectively, thus the “trade-off” was effectively improved by loading of Multi CNC. Moreover, the flux recovery ratio (FRR) of MCP1 (FRR = 74.08 %) was 2.1 times as much as the original PES membranes (FRR = 34.81 %) in the water-BSA-water filtration process, verified that the introduction of Multi CNC could effectively improve the anti-fouling ability of composite membranes. Such hydrophilic composite ultrafiltration membranes with robust mechanical performance could be developed for pharmaceutical and biotechnological industries.

Facile engineering of PES ultrafiltration membranes using polyoxometalates for enhanced filtration and antifouling performance

The pursuit of augmented membrane separation performance is mainly proceeded by breaking the permeability-selectivity trade-off and ameliorating the membrane fouling propensity. Here, we report the usage of phosphomolybdic acid (PMo12) as a functional additive to fabricate poly (ether sulfone) (PES) based composite ultrafiltration membranes via a non-solvent induced phase separation process. In contrast to the control PES membrane, the introduction of PMo12 endowed the composite membranes with increased surface pore density, porosity and selective layer thickness as well as the enhanced hydrophilicity and charge property through altering the phase inversion rate, thereby resulting in a significantly increased filtration performance. Specifically, the optimized composite membrane presented a water flux of 572.67 ± 21.73 L·m−2·h−1 and a bovine serum albumin rejection of 99.31 ± 0.22 %, which are ca. 340 % and 0.7 % higher than those of the control PES membrane, respectively. Importantly, the composite membrane also displayed enhanced anti-organic and anti-biofouling properties with the assistance of the introduced PMo12. This work provides an efficient pathway to simultaneously enhance the filtration and antifouling performance toward the further advancement of UF membrane for water purification.

Robust fabrication of poly(lactic acid) membrane with good hemocompatibility over heparin‐mimetic graphene‐based nanosheets

AbstractDeveloping dislysis membranes with outstanding hemocompatibility is the key of hemodialysis used for curing the kidney malfunction. Herein, polylactic acid (PLA) membrane with high water flux (640.2 L m−2 h−1) and bovine serum albumin (BSA) rejection (>97%) is prepared and subsequently modified by heparin‐mimetic sulfonated graphene oxide (SGO) via modified mussel‐inspired method. The (NH4)2Fe(SO4)2 serves as Fenton catalyst significantly accelerates the oxidized polymerization of dopamine (DA) in DA‐g‐SGO to form polydopamine‐g‐SGO (PDA‐g‐SGO). The uniform immobilization of SGO significantly improves the hydrophilicity and electronegativity of the PLA membranes, inhibiting platelets adhesion. Moreover, the sulfonic group of SGO plays the role of anticoagulant as heparin. The obtained PLA/PDA‐g‐SGO membrane exhibits excellent hemocompatibility with longer recalcification time (230 s) and lower hemolysis ratio (1.6%) than those of original PLA membrane (120 s, 10.7%). This study demonstrates a potential way to improve the hemocompatibility of polymeric membranes.