Polysulfone Ultrafiltration Membranes Research Articles

A novel antifouling and thermally stable polysulfone ultrafiltration membranes with sulfobetaine polyimide as porogen

Polysulfone ultrafiltration membranes were prepared with sulfobetaine polyimide (s‐PI) via phase inversion process, during which s‐PI migrated and enriched on the surfaces of membranes/pores due to its hydrophilic nature. Therefore, s‐PI not only enhanced surface hydrophilicity, but also acted as a pore‐forming agent. It was proved that the introduction of s‐PI effectively promoted membrane porosity and antifouling ability. Under optimized conditions, the pure water flux of blend membranes reached 220.58 L m−2 h−1 with a protein rejection ratio of 99.3%, and a flux recovery ratio of 90.86%, indicating the superior antifouling property and filtration performances of zwitterionic polymer blend membranes. Moreover, the blend membrane can stand a temperature of 90°C without degrading its separation performance. Besides excellent thermal stability, the blend membranes exhibited a distinctly advanced mechanical strength due to the addition of rigid s‐PI polymer. Overall, this study provided a facile and scalable method for the preparation of antifouling and thermally stable ultrafiltration membranes.

Polysulfone/halloysite composite membranes with low fouling properties and enhanced compaction resistance

In the present study, polysulfone (PSF) ultrafiltration membranes incorporated with varying amounts of halloysite nanotubes (Hal) were fabricated via immersion precipitation membrane casting technique. Membrane characterization by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM) revealed that the composite membranes showed notable changes in the morphology, roughness, and distribution of Hal within the membrane matrix. SEM images, pore size, and porosity estimations indicated that the incorporation of low to medium Hal loadings resulted in PSF/Hal membranes with smaller surface pore size, lower porosity, and thicker top skin layer due to the strong interfacial interactions between Hal and PSF matrix. The addition of 5 wt% Hal reduces the composite membrane's contact angle by 14o from the 78.7o of the pristine membrane. The incorporation of 0.2 wt% Hal resulted in a 140% increase in the top surface Young's modulus of the composite membrane, and a notably reduced adhesion of hydrophobic foulants compared to the pristine PSF membrane. During the filtration of bovine serum albumin (BSA) and skimmed milk (SM) solutions, the PSF membranes incorporated with 0.2 and 0.5 wt% Hal showed excellent rejection and flux recovery as well as revealed strong anti-fouling and compaction resistance properties.

Fouling resistant, high flux, charge tunable hybrid ultrafiltration membranes using polymer chains grafted graphene oxide for NOM removal

The unprecedented performance of fouling resistant, high flux and high rejection hybrid ultrafiltration polysulfone membranes with charge tunable channels using functionalized polymer chains grafted graphene oxide (SPK-g-GO) nanosheets for natural organic matter removal from aqueous feed is herein reported. The novel SPK-g-GO nanosheets were first prepared by esterification reaction at 55 °C using hydroxylated sulfonated poly(ether ether ketone) and graphene oxide. Then, polysulfone blend hybrid membranes with charge tunable channels were produced via the non-solvent induced phase separation method and optimized by varying the SPK-g-GO concentration from 1 to 8 wt.% in the casting solution. The membranes were characterized using scanning electron microscopy, Raman spectroscopy, atomic force microscopy, surface zeta potential and contact angle measurements. The surface texture and hydrophilicity of the membranes were altered due to the incorporation of SPK-g-GO. The hybrid membrane’s water flux was highly dependent on the amount of SPK-g-GO incorporated within the membrane matrix. The maximum water flux (485.7 L m−2 h−1), obtained using the membrane with 4 wt.% SPK-g-GO, was almost 270% higher than that of the membrane without SPK-g-GO (181.1 L m−2 h−1). The fouling resistance and natural organic matter retention capabilities of the membranes were examined via UF tests of synthetic natural organic matter solution at 1 bar feed pressure and neutral pH. The hybrid membrane with 4 wt.% SPK-g-GO loading exhibited remarkable improvement over the pristine one, rejecting more than 86% of the and recovering ~90% of its initial water flux after washing with a stable retention rate during a long-term filtration test.

Performance enhancement of commercial ultrafiltration polysulfone membrane via in situ polymerization of aniline using copper chloride as a catalyst

AbstractBACKGROUNDPolyaniline is well known for enhancing hydrophilicity and antifouling properties, which could be beneficial for protein separation processes in membranes. The development of polyaniline in the presence of cupric chloride as an oxidant was a target for better distribution.RESULTSBiofouling‐resistant hydrophilic membrane surfaces were developed via in situ polymerization of aniline on a polysulfone membrane surface. Membrane surface modifications were made with various percentages of monomer (0.5, 1 and 2%). All the modified membranes exhibited improved membrane surface properties. The modified membrane (Poly(Sulf‐Ani‐2)) containing 2% aniline as a monomer in polymerization solution showed the best hydrophilicity, exceptional permeability and better protein rejection ability as well as enhanced anti‐biofouling property.CONCLUSIONSIn situ polyaniline attachment might be an easy and beneficial technique for the fabrication of hydrophilic membrane surfaces for large‐scale industrial applications. The attachment of polyaniline on polysulfone membrane surfaces through in situ polymerization in the present study proved to be an advanced approach for crafting better membranes with considerable hydrophilicity and fouling control enhancement.

Modification of Polysulfone Ultrafiltration Membranes via Addition of Anionic Polyelectrolyte Based on Acrylamide and Sodium Acrylate to the Coagulation Bath to Improve Antifouling Performance in Water Treatment.

Surface modification of polysulfone ultrafiltration membranes was performed via addition of an anionic polymer flocculant based on acrylamide and sodium acrylate (PASA) to the coagulation bath upon membrane preparation by non-solvent induced phase separation (NIPS). The effect of PASA concentration in the coagulant at different coagulation bath temperatures on membrane formation time, membrane structure, surface roughness, hydrophilic-hydrophobic balance of the skin layer, surface charge, as well as separation and antifouling performance was studied. Scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, contact angle and zeta potential measurements were utilized for membrane characterization. Membrane barrier and antifouling properties were evaluated in ultrafiltration of model solutions containing human serum albumin and humic acids as well as with real surface water. PASA addition was found to affect the kinetics of phase separation leading to delayed demixing mechanism of phase separation due to the substantial increase of coagulant viscosity, which is proved by a large increase of membrane formation time. Denser and thicker skin layer is formed and formation of macrovoids in membrane matrix is suppressed. FTIR analysis confirms the immobilization of PASA macromolecules into the membrane skin layer, which yields improvement of hydrophilicity and change of zeta potential. Modified membrane demonstrated better separation and antifouling performance in the ultrafiltration of humic acid solution and surface water compared to the reference membrane.

Eco-friendly solvents and their mixture for the fabrication of polysulfone ultrafiltration membranes: An investigation of doctor blade and slot die casting methods

Nonsolvent induced phase separation has been widely used to fabricate polymeric membranes. Common solvents, such as dimethylacetamide (DMAc) and N-Methyl-2-pyrrolidone (NMP), are toxic and not environmentally friendly; therefore, eco-friendly alternatives are needed. Eco-friendly solvents, such as Rhodiasolv® PolarClean (PolarClean) and γ-valerolactone (GVL), have been investigated to replace DMAc and NMP at the laboratory scale; however, not extensively at the production scale. In this work, the feasibility of fabricating polysulfone (PSf) ultrafiltration membranes using eco-friendly solvents at laboratory and production scales is investigated. First, it was determined that the addition of GVL to dope solutions of PolarClean could reduce the original preparation time at a rotation speed of 450 RPM by two-thirds, and by three-quarters at 600 RPM. Furthermore, dope solutions exhibit Newtonian fluid behavior. Doctor blade extrusion and a roll-to-roll (R2R) system integrated with slot die casting are used to fabricate the PSf ultrafiltration membranes at laboratory and production scales, respectively, and the resulting membranes are compared structurally, morphologically and operationally.The chemical structure of membranes is not affected by the use of different solvents or by the differences in fabrication scale. On the other hand, cross-sectional images show that the structures of the membranes are different, most likely due to differences in diffusion rates between the different solvents/co-solvents into the nonsolvent, water. Furthermore, it has been observed that the roughness values of the membranes relative to the fabrication process is different, possibly due to differences in the required evaporation time. All membranes display similar operational parameters, i.e., flux decline, permeability and recovery, during bovine serum albumin (BSA) filtration. Therefore, this study shows that PSf membranes fabricated using eco-friendly solvent mixtures are comparable to traditional membranes, cast using petroleum-derived solvents, and are scalable using slot die casting on a R2R.

Surface modification of high-rejection ultrafiltration membrane with antifouling capability using activated oxygen treatment and metallic glass deposition

Polysulfone (PSf) composite ultrafiltration membranes were subjected to Ar/O2 plasma assisted oxygen activation and then coated with various forms of metallic glass (W50Ni25B25, Zr60Cu25Al10Ni5, and Pd74Si14Cu12). The activated oxygen treated PSf ultrafiltration membrane was strongly hydrophilic, with pure water flux (PWF) of 350.7 L m−2 h−1 and bovine serum albumin (BSA) rejection of 83%. The application of metallic glass (MG) to the surface of the polysulfone composite membrane using low-power radio-frequency magnetron sputtering improved the BSA rejection rate (ranging from 98.6 to 99.9%) with only a slight reduction in PWF: tungsten-based MG (321.5 L m−2 h−1), zirconium-based MG (215.6 L m−2 h−1), and palladium-based MG (181.3 L m−2 h−1). The membrane with the tungsten-based coating achieved remarkable PWF, BSA rejection, and antifouling performance, due primarily to high surface hydrophilicity (water contact angle of 24.2°) and a strongly negative surface charge. Overall, the proposed metallic glass/polysulfone composite membranes achieved moderately high PWF and protein rejection with incredible antifouling competence, even under extended (multi-cycle) fouling conditions.

Stimuli responsive mixed matrix polysulfone ultrafiltration membrane for humic acid and photocatalytic dye removal applications

Current work discusses the synthesis and characterization of a pH and thermo-responsive poly (N-vinylcaprolactam-TiO2-acrylic acid) (VCL-TiO2-AA) polymer nanocomposite in various compositions of TiO2 and application of these nanocomposites for the modification of polysulfone (PSF) membranes. The stimuli responsive nanocomposite was directly blended to the membrane casting solution and this casting solution was used to synthesize membranes by phase inversion method. The modified membranes were analyzed for their hydrophilic, photocatalytic, pH, and thermo-responsive behavior. The membranes were characterized for their morphology by using FESEM. FTIR and FESEM-EDX analysis were carried out to analyze their elemental analysis. Furthermore, the effect of the synthesized stimuli responsive VCL-TiO2-AA polymer nanocomposite was analyzed on the membrane performance in terms of fouling, temperature and pH responsiveness, and photocatalytic removal of MB dye under dark and UV light conditions at different pH values. Furthermore, the ultrafiltration performance and antifouling nature of the modified membranes were investigated and analyzed.

Enhancement of Industrial Effluents Quality by Using Nanocomposite Mg/Al LDH Ultrafiltration Membranes

In this paper, Mg–Al-Acr LDH and Mg–Al-Amps LDH nanocomposites were synthesized via reacting of acrylic acid and 2-acrylamido2-methylpropansulfonic acid with Mg–Al LDH by chelation technique. The nanocomposite LDHs were applied as a hydrophilic fillers for modification of polysulfone (PSf) ultrafiltration membrane. The Mg–Al LDH/PSf, Mg–Al-Acr LDH/PSf and Mg–Al-Amps LDH/PSf membranes were fabricated using induced phase-blending method. The chelated LDHs and UF membranes were characterized using Atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and thermogravimetric analyses. In contrast to the neat PSf film, the Mg–Al-Acr LDH/PSf and Mg–Al-Amps LDH/PSf nanocomposite membranes exhibited higher pore size, porosity, hydrophilicity and lower surface roughness. The finger-like structures demonstrated for neat PSf membrane in cross-section SEM images were collapsed in Mg–Al-Acr LDH/PSf and Mg–Al-Amps LDH/PSf nanocomposite membranes. The synthesized PSf films were optimized in the presence of suitable content of hydrophilic LDHs (0.1 wt%). Not only the modified PSf membranes, when compared with the neat membrane, show a higher pure water flux of 300 and 390 l m−2 h for 0.1 wt% Mg–Al-Acr LDH/PSf and Mg–Al-Amps LDH/PSf membranes, respectively, but also the antifouling of the optimal nanocomposite films was enhanced. Moreover, the TOC of the wastewater decreased from 140.8 to 44 and 30.8 mg l−1, correspondingly. Finally, with a higher water permeation and humic acid rejection, those equipped films turned to be more attractive and excellent for effluent features enhancement.

A novel Polysulfone/Iron-Nickel oxide nanocomposite membrane for removal of heavy metal and protein from water.

Making a nanocomposite membrane is an effective way of producing membranes with desired functionality, better permeance. In this work, virgin polysulfone ultrafiltration (UF) membrane and nanocomposite membranes with different concentrations ranging from 100 to 2,000mg/L iron-nickel oxide in polysulfone matrix were prepared by phase inversion method. The performances of prepared membranes were evaluated by pure water permeance testing, protein rejection, and lead rejection. Up to 99.66% removal of lead was achieved by nanocomposite membrane. The structure and property of membranes were analyzed by scanning electron microscopy (SEM), powder X-ray diffractometer (XRD), and atomic force microscopy (AFM) and zeta potential analysis. The nanocomposite membranes showed higher water permeance as compared to virgin ultrafiltration membrane. The membrane with 750mg/L concentration of iron-nickel oxide nanoparticle demonstrated the increase in water flux by 117.85% as compared to the virgin ultrafiltration membrane. Higher albumin rejection and lead rejection were achieved by nanocomposite membrane as compared to polysulfone membrane. Leaching study of nanomaterial in water was undertaken, and it was found the leaching of nanomaterial was minimal. Increase in surface roughness, increase in number of pores with decrease in pore size, led to improvement in ultrafiltration performance by increased selectivity and permeance of the membrane. © 2020 Water Environment Federation PRACTITIONER POINTS: The nanocomposite ultrafiltration membrane with iron-nickel oxide nanomaterial. Upto 117.85% increase in pure water permeance as compared to virgin membrane. Upto 99.66% lead rejection and upto 96.8% albumin rejection from aqueous solution. Little or no leaching of nanomaterials in water. Increased selectivity and productivity of membrane.

Photo-Fenton assisted self-cleaning hybrid ultrafiltration membranes with high-efficient flux recovery for wastewater remediation

Membrane fouling problems severely hindered the integrated development of membrane technology. Currently, construction of a fouling-resistance membrane was an everlasting and ubiquitous research focus. In this study, β-FeOOH nanorods were anchored onto commercial polysulfone (PSF) ultrafiltration (UF) membranes surface via in-situ mineralization to fabricate an anti-fouling UF membrane for organic and dyes wastewater treatment. The ion-dipole interaction and π-cation interaction between Fe3+ and PSF chains guaranteed β-FeOOH nanorods attaching onto the surface without an intermediate layer. A satisfying flux recovery ratio (93.6% and 94.3%) and a low irreversible fouling ratio (6.4% and 5.9%) for bovine albumin (BSA) and sodium alginate (SA) solutions, respectively, were acquired on account of the photo-Fenton catalytic property and hydrophilicity of nanorods without sacrificing the permeation flux sharply. Importantly, the resultant membrane exhibited a desirable separation performance for various dyes solutions, with high permeation flux (53.6–100.0 L·m−2·h−1·bar−1) and appropriate rejection rates (60.9–92.6%). This work not only improved the anti-organic fouling performance extensively, but also provided a novel insight to decorate the conventional UF membrane surface straightforward without an intermediate layer.

Tailoring polyethersulfone/quaternary ammonium polysulfone ultrafiltration membrane with positive charge for dye and salt selective separation

AbstractPolyethersulfone (PES)/quaternary ammonium polysulfone (QAPSf) blend ultrafiltration (UF) membranes with positive charge were fabricated by nonsolvent induced phase separation (NIPS) for use in dye and salt selective separation. QAPSf was synthesized by nucleophilic substitution with chloromethylated polysulfone (CMPSf). The effect of the PES/QAPSf mass ratio on the morphology and performance of blend UF membranes were studied. The membranes' zeta potentials gradually changed from negative to positive with decreases in the PES/QAPSf mass ratio. At PES/QAPSf mass ratios of 30:70 and 10:90, the zeta potentials of the membranes reached +1.8 mV and + 5.9 mV, respectively. Additionally, the contact angles of the membranes decreased from 74° to 52° as the QAPSf content increased from 0 wt% to 90 wt%. Furthermore, the membrane with a PES/QAPSf mass ratio of 30:70 showed a high water permeance (181.4 LMH bar−1) and excellent dye and salt selective separation performance. The rejection ratios reached 99.1%, 87.8%, 99.6%, and 92.4% for dyes Congo red, methyl blue, Alixin blue 8GX, and basic blue 24, respectively, while those for salts Na2SO4, MgSO4, MgCl2, and NaCl were ≤ 10%. In addition, the PES/QAPSf membranes showed excellent antifouling performance and good operating stability with dye‐salt mixtures of various pHs and salt concentrations.

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

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

One-Step Preparation of Antifouling Polysulfone Ultrafiltration Membranes via Modification by a Cationic Polyelectrolyte Based on Polyacrylamide.

A novel method for one-step preparation of antifouling ultrafiltration membranes via a non-solvent induced phase separation (NIPS) technique is proposed. It involves using aqueous 0.05–0.3 wt.% solutions of cationic polyelectrolyte based on a copolymer of acrylamide and 2-acryloxyethyltrimethylammonium chloride (Praestol 859) as a coagulant in NIPS. A systematic study of the effect of the cationic polyelectrolyte addition to the coagulant on the structure, performance and antifouling stability of polysulfone membranes was carried out. The methods for membrane characterization involved scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), contact angle and zeta-potential measurements and evaluation of the permeability, rejection and antifouling performance in human serum albumin solution and surface water ultrafiltration. It was revealed that in the presence of cationic polyelectrolyte in the coagulation bath, its concentration has a major influence on the rate of “solvent–non-solvent” exchange and thus also on the rate of phase separation which significantly affects membrane structure. The immobilization of cationic polyelectrolyte macromolecules into the selective layer was confirmed by FTIR spectroscopy. It was revealed that polyelectrolyte macromolecules predominately immobilize on the surface of the selective layer and not on the bottom layer. Membrane modification was found to improve the hydrophilicity of the selective layer, to increase surface roughness and to change zeta-potential which yields the substantial improvement of membrane antifouling stability toward natural organic matter and human serum albumin.

Polydopamine Bilayer Nanofiltration Membranes with Excellent Resistance to Delamination

Bilayer nanofiltration (NF) membranes tend to delaminate and have poor stability when applied in organic solvents due to their bi-layered structure. In this study we prepared two types of polydopamine (PDOPA) modified NF membranes including PDOPA-TMC (trimesoyl chloride)/PSF and PDOPA/PIP(Piperazine)-TMC/PSF NF membranes on polysulfone (PSF) ultrafiltration membranes via interfacial polymerization based on PDOPA’s specialized molecular structure and high adhesion property. The separation performance and stability of the NF membranes were investigated. Both the polyester bonds of the PDOPA bilayer membranes and the bioadhesion of the PDOPA were simultaneously beneficial to improving the structure and chemical stabilities of the bilayer membranes. After soaking both the PDOPA-TMC/PSF and PDOPA/PIP-TMC/PSF NF membranes in ethanol solvent for 12 days, the rejection of Congo red only decreased by 1.8% (original, 99.9%) and 1.2% (original, 99.9%), respectively. For the PDOPA/PIP-TMC/PSF NF membrane, the rejection of Na2SO4 was only reduced by 1.6% (original, 98.5%). Moreover, the separation performances of both the PDOPA-TMC/PSF and PDOPA/PIP-TMC/PSF NF membranes were still excellent after soaking in a sodium hypochlorite solution (50 ppm) for 240 h (12,000 ppm·hours). The NF membranes thus exhibited long-term structural stability in ethanol and excellent chemical stability in the sodium hypochlorite solution. In particular, no delamination was observed in the above experiments, which is significant for their use in the wastewater treatment field.

Improved Performance of Polysulfone Ultrafiltration Membrane Using TCPP by Post-Modification Method.

Ultrafiltration (UF) membranes have found great application in sewage purification and desalination due to their high permeation flux and high rejection rate for contaminants under low-pressure conditions, but the flux and antifouling ability of UF membranes needs to be improved. Tetrakis (4-carboxyphenyl) porphyrin (TCPP) has good hydrophilicity, and it is protonated under strongly acidic conditions and then forms strong hydrogen bonds with N, O and S, so that the TCPP would be well anchored in the membrane. In this work, NaHCO3 was used to dissolve TCPP and TMC (trimesoyl chloride) was used to produce a strong acid. Then, TCPP was modified in a membrane with a different rejection rate by a method similar to interfacial polymerization. Performance tests of TCPP/polysulfone (PSf) membranes show that for the membrane with a high BSA (bovine serum albumin) rejection, when the ratio of NaHCO3 to TCPP is 16:1 (wt.%), the pure water flux of membrane Z1 16:1 is increased by 34% (from 455 to 614 Lm−2h−1bar−1) while the membrane retention was maintained above 95%. As for the membrane with a low BSA rejection, when the ratio of NaHCO3 to TCPP was 32:1, the rejection of membrane B2 32:1 was found to increase from 81% to 96%. Although the flux of membrane B2 32:1 decreased, it remained at 638 Lm−2h−1bar−1, which is comparable to the reported polymer ultrafiltration membrane. The above dual results are thought to be attributed to the synergistic effect of protonated TCPP and NaHCO3, where the former increases membrane flux and the latter increases the membrane rejection rate. This work provides a way for the application of porphyrin and porphyrin framework materials in membrane separation.

Polysulfone Ultrafiltration Membrane Promoted by Brownmillerite SrCuxCo1–xO3−λ-Deposited MCM-41 for Industrial Wastewater Decontamination: Catalytic Oxidation and Antifouling Properties

A polysulfone (PSf) ultrafiltration (UF) membrane without a chemical reaction process is unable to deeply clean industrial wastewater and prone to fouling. In this work, a 30 mol % Cu-substituted b...

Preparation and characterization of novel nanoporous SBA-16-COOH embedded polysulfone ultrafiltration membrane for protein separation

Polysulfone ultrafiltration membrane was modified by novel nanoporous SBA-16-COOH during the membrane preparation via the phase inversion. The pure water flux and bovine serum albumin (BSA, as the foulant) flux were measured at 2 bar and the membranes’ antifouling behavior were analyzed. The membranes showed higher water flux after SBA-16-COOH addition up to 2 wt% and after that the flux slightly decreased which is attributed to the aggregation of SBA-16-COOH particles at the higher concentrations. SBA-16-COOH addition improved the surface hydrophilicity and led to elongated finger-like pores within the membranes cross section structure. The water flux after BSA flux was still higher than the one before BSA, thereby SBA-16-COOH addition resulted in better antifouling properties. In terms of BSA rejection, the nanocomposite SBA-16-COOH-based membranes outperform the pristine PSf membrane with rejection values up to 98.9%. The water contact angle confirmed the enhanced hydrophilicity of the membranes’ surface due to COOH functional groups of the nanomaterials which led to a higher permeability and an enhanced fouling resistance.

Fabrication of polyamide thin film nanocomposite reverse osmosis membrane incorporated with a novel graphite‐based carbon material for desalination

AbstractThe properties of polyamide (PA) thin film composite (TFC) membranes are affected by many variables, especially the additives in the process of interfacial polymerization that play an important role in the properties of membranes. In this study, a new type graphite carbon was added into organic phase containing trimesoyl chloride for interfacial polymerization with aqueous phase containing m‐phenylenediamine to prepare modified polyamide thin film nanocomposite (TFN) membranes for reverse osmosis (RO) adhibition. Polysulfone ultrafiltration membranes were used as the carrier of the interfacial polymerization. The concentration of graphite carbon was selected from 0.002 to 0.01 wt%. The polyamide nanocomposite membrane prepared with the concentration of 0.004 wt% graphite carbon showed the best RO desalination performance, which the water flux of this TFN membrane is over 2.3 times as much as pristine TFC membrane, and the salt rejection is over 99%. This article provides a well‐performing polyamide thin film nanocomposite membrane modified by a new‐type carbon nanoparticles consequently.

Low‐fouling polysulfone ultrafiltration membranes with amphiphilic sulfobetaine polyamide as additive

AbstractIn this study, amphiphilic sulfobetaine polyamide (sPA) oligomers with sulfobetaine as end groups and arylamide as backbone were synthesized as the pore‐forming additive for the preparation of polysulfone membranes. This additive showed good solubility and compatibility with the membrane casting solution due to the self‐assembly behaviors of sPA in organic solvent. Moreover, the effects of hydrophobic chain length and additive dosage on membrane morphology, hydrophilicity, permeability, antifouling, and mechanical properties were systematically studied. In view of these results, it can be concluded that the higher content and smaller size of sPA in the casting solution correlated with better filtration and separation performances of the membranes. Results showed that the pure water flux increased from 68.2 L m−2 hr−1 for the pristine membrane to a maximum of 205 L m−2 hr−1 for the blend membrane, meanwhile, the protein rejection ratio was above 95.2% and the flux recovery ratio was promoted from 68.3% to above 85.0%. The fouling resistance of the blend membranes was further demonstrated by significantly reduced protein/bacteria adhesion. And consistent high‐performances in filtration and separation were demonstrated after the blend membranes were treated at 90°C.