Blend Membranes Research Articles

Functional Properties of Grapefruit Seed Extract Embedded Blend Membranes of Poly(vinyl alcohol)/Starch: Potential Application for Antiviral Activity in Food Safety to Fight Against COVID-19.

The poly(vinyl alcohol) (PVA) and starch-based polymeric films with a ratio of 2:8 were prepared using solution casting followed by a solvent evaporation method. Four types of membranes with varied concentrations of grapefruit seed extract (GSE) i.e., 2.5-10 wt% was incorporated in the films. The prepared membranes were assessed for transparency test, mechanical properties, surface morphology, permeability test for O2, and antimicrobial properties. The PVA/starch-10% GSE loaded film showed excellent mechanical properties showing highest 1344 ± 0.7% elongation at break but poor optical transparency with 53.8% to 68.61%. The Scanning Electron Microscopic study reveals the good compatibility between the PVA, Starch, and GSE. The gas permeability test reveals that the prepared films have shown good resistance to the O2 permeability 0.0326-0.316 Barrer at 20kg/cm2 feed pressure for the prepared membranes showing excellent performance. By adding the little amount of GSE into the PVA/starch blend membranes showed promising antimicrobial efficacy against MNV-1. For 4h. incubation, PVA/starch blend membranes containing 2.5%, 5%, and 10% GSE caused MNV-1 reductions of 0.92, 1.89, and 2.27 log PFU/ml, respectively. Similarly, after 24h, the 5% and 10% GSE membranes reduced MNV-1 titers by 1.90 and 3.26 log PFU/ml, respectively. Antimicrobial tests have shown excellent performance to resist microorganisms. The water uptake capacity of the membrane is found 72% for the PVA/starch pristine membrane and is reduced to 32% for the 10% GSE embedded membrane. Since the current pandemic situation due to COVID-19 occurred by SARSCOV2, the prepared GSE incorporated polymeric blend films are the rays of hope in the packaging of food stuff.

Transport properties of polymer blends and composite membranes for selective permeation of hydrogen

Graphene Oxide (GO) dispersed in a polymer blend of Polystyrene (PS)/Poly (methyl methacrylate) (PMMA) nanocomposite membranes have been prepared by the solution cast method for hydrogen gas permeation application. This paper reports a study of blends of PMMA and PS that were prepared in different ratios of weight percentage for PMMA: PS (80:20, 50:50 and 60:40) composite with 1 wt% of GO and 2 wt% of GO. The structural and morphological properties of these prepared composite membranes have been characterized using gas permeation, Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). UV Spectroscopy and FT-IR have carried out the optical absorbance measurement of the composite membranes. The permeability measurements indicate that the GO nanofillers in blends of PS/PMMA have shown higher permeability for hydrogen gas than that of pure polymers. The gases used for the permeation measurements were H2, CO2, N2 and CH4. Selectivity has been calculated for H2/CO2, H2/N2 and H2/CH4 gas pairs and plotted to show Robeson's 2008 upper bound and compared with reported data. The transport properties of these gases have been compared with that of a neat membrane. The permeability of all gases has increased to that of the unmodified polymer membrane. The selectivity measurements show that GO composite with PS/PMMA blend membranes is highly selective for hydrogen gas from different gas pairs, therefore, these composite membranes can be used for hydrogen purification. There is a trade-off between permeability and selectivity parameters; GO nanofillers keep selectivity constant as permeability increases, which the nanogap theory could explain.

Polyisatin derived ion-solvating blend membranes for alkaline water electrolysis

It is a great challenge to develop membranes based on polyaromatic backbone chemistries that combine high alkaline resistance with high ionic conductivity and low gas crossover for alkaline water electrolysis. Hence, a new alkaline stable aromatic monomer containing side ion-solvating poly(ethylene oxide) (PEO) groups was synthesized and polymerized with isatin and biphenyl via super acid catalyzed hydroxyalkylation to yield ion-solvating copolymers. The prepared aryl-ether free backbone aromatic copolymers (P(IB-PEO)-y) have excellent film-forming properties, high thermal stability, but moderate KOH electrolyte uptake and relatively low conductivity. Therefore, to further enhance the electrolyte uptake and ionic conductivity, P(IB-PEO)-20 copolymers were blended with polybenzimidazole in ratios 80/20, 70/30, 60/40 and 50/50. The prepared blend membranes exhibit high electrolyte uptakes (up to 97 wt%) while the highest ionic conductivity of 110 mS cm−1 at 80 °C was observed for PBI80/P(IB-PEO) blend. The KOH doped PBI70/P(IB-PEO) membrane shows a tensile strength of 20 MPa and a significant increase in Young's modulus (131%) compared to that of PBI80/P(IB-PEO). The alkaline stability test demonstrated that PBI80/P(IB-PEO) membrane exhibits a substantially higher Young's modulus (144% increase) than non-aged analogue, after 1 month in 20 wt% KOH solution at 80 °C. Further, PBI80/P(IB-PEO) and PBI70/P(IB-PEO) membranes retained 96–98% of their original conductivity after aging, indicating their excellent alkaline resistance. Selected membranes were tested in a single cell electrolyzer to probe feasibility and crossover behaviour.

Development of CO2‐Philic Blended Membranes Using PIM–PI and PIM–PEG/PPG

AbstractBlending is a simple method through which one can effectively tailor new polymers exhibiting the properties of their parent ones. Because the original properties of polymers are maintained after blending, various studies have used these films as gas separation membranes. In this study, a new CO2 separation membrane is developed by physically mixing a polymer of intrinsic microporosity (PIM) with high gas permeability, polyimide (PIM‐PI), as the hard segment and CO2‐philic PIM‐poly(ethylene glycol)/poly(propylene glycol), or PIM‐PEG/PPG, as the soft segment. Prepared by adding 5 mol.% of PIM‐PEG/PPG to PIM‐PI, the blended membrane PPB‐5, with a tensile strength of 54 MPa and 35.5% elongation at break, shows better mechanical properties than commercial high‐performance polymer membranes developed for gas separation, PEG‐based blended membranes, and corresponding copolymer membranes with similar compositions developed in a previous study. In addition, it shows high CO2 permeability (1552.6 Barrer) and CO2/N2 selectivity (29.3) due to the well‐developed microphase separation characteristics originating from the optimal two‐component composition, and the gas separation performance is close to the Robeson (2008) upper bound.

Incorporation of MIL-101(Fe)/Tannic acid-PEG to PES-TPU blend membrane to modify a membrane with riveting mechanical stability and separation performance

A certain amount of thermoplastic polyurethane (TPU) was added to polyethersulfone (PES) to ensure higher mechanical stability. The tannic acid-polyethylene glycol (TA-PEG) and aminated metal‐organic framework-101 (Fe) (MIL-101(Fe)) were incorporated into the membrane matrix separately, then an equal mass ratio of each was incorporated into the membrane matrix, and the results were compared. The optimized membrane with dual nanoparticles elucidates a high-water permeation rate that reached 8.12 L/m2.h.bar, which is almost 4 times higher than the PES-TPU pristine membrane. The optimum membrane provided a high dye rejection property (98.3 ± 0.4 %, 98.9 ± 0.3 %, 99.0 ± 0.3 %, 99.4 ± 0.2 %, and 99.7 ± 0.2 %) for Methylene Blue (MB), Crystal Violet (CV), Methyl Green (MG), Direct Red-16 (DR-16), and Direct Yellow-29 (DY-29), respectively. Subsequently, significant antifouling features (FRR = 91.2 % for the optimized membrane) were obtained, and irreversible fouling dropped remarkably. The long-term water permeation and rejection rates were also investigated, and it was found that the optimized membrane enhanced in both, where even after 10 days, the optimized membrane maintained its initial rejection rate for all tested dyes.

Fabrication of Ti2SnC-MAX Phase Blended PES Membranes with Improved Hydrophilicity and Antifouling Properties for Oil/Water Separation.

In this research work, the Ti2SnC MAX phase (MP) was synthesized via the reactive sintering procedure. The layered and crystalline structure of this MP was verified by SEM, HRTEM, and XRD analyses. This nano-additive was used for improvement of different features of the polyethersulfone (PES) polymeric membranes. The blended membranes containing diverse quantities of the MP (0-1 wt%) were fabricated by a non-solvent-induced phase inversion method. The asymmetric structure of the membranes with small holes in the top layer and coarse finger-like holes and macro-voids in the sublayer was observed by applying SEM analysis. The improvement of the membrane's hydrophilicity was verified via reducing the contact angle of the membranes from 63.38° to 49.77° (for bare and optimum membranes, respectively). Additionally, in the presence of 0.5 wt% MP, the pure water flux increased from 286 h to 355 L/m2 h. The average roughness of this membrane increased in comparison with the bare membrane, which shows the increase in the filtration-available area. The high separation efficiency of the oil/water emulsion (80%) with an improved flux recovery ratio of 65% was illustrated by the optimum blended membrane.

Fabrication of high-performance mixed matrix blend membranes comprising PES and TPU reinforced with APTS functionalized-graphene oxide via VIPS-NIPS technique for aqueous dye treatment and antifouling properties

BackgroundIn recent decades, the preparation and design of nanofiltration (NF) membranes were significantly progressed for dye rejection application in various industries, such as the textile industry. Moreover, it is well-known that the membrane antifouling property is another factor that is very important in evaluating NF membrane performance. MethodsIn this article, some NF membranes have been fabricated by the incorporation of various amounts of polyethersulfone (PES), thermoplastic polyurethane (TPU), and APTS functionalized-graphene oxide (GO-APTS) nanosheets. The GO-APTS nanosheets has been prepared utilizing the improved hummer's procedure for the fabrication of graphene oxide (GO), followed by adding (3-aminopropyl) triethoxysilane (APTS). The mixed matrix membranes (MMMs) have been generated via the VIPS-NIPS procedure to enhance the removal performance of the prepared membranes. Tensile analyses data exhibited that TPU blending and GO-APTS embedding into the PES improve the tensile strength and elongation at break of the prepared membranes. Significant FindingsThe dye removal ability of the membranes has been studied in terms of removing methylene blue (MB), crystal violet (CV), methyl green (MG), and direct yellow 29 (DY-29). It is worth pointing out that due to the superior permeation (5.08 L/m2.h.bar) along with the outstanding separation ability (97.3%, 98.1%, 98.7%, and 99.4% for MB, CV, MG, and DY-29, respectively), the optimized nanoparticle-containing membrane (M7) was selected as the excellent membrane in dye separation. Suitable hydrophilicity of TPU and GO-APTS also turned the M7 membrane into a membrane with high resistance against fouling, so the FRR and Rt values reached 92.9% and 53.2%, respectively.

Ionic Liquids-Polymer of Intrinsic Microporosity (PIMs) Blend Membranes for CO2 Separation.

Membranes with high CO2 solubility are essential for developing a separation technology with low carbon footprint. To this end, physical blend membranes of [BMIM][Ac] and [BMIM][Succ] as Ionic Liquids (ILs) and PIM-1 as the polymer were prepared trying to combine the high permeability properties of PIM-1 with the high CO2 solubility of the chosen ILs. Membranes with a PIM-1/[BMIM][Ac] 4/1 ratio nearly double their CO2 solubility at 0.8 bar (0.86 cm3 (STP)/cm3 cmHg), while other ratios still maintain similar solubilities to PIM-1 (0.47 cm3 (STP)/cm3 cmHg). Moreover, CO2 permeability of PIM-1/[BMIM][Ac] blended membranes were between 1050 and 2090 Barrer for 2/1 and 10/1 ratio, lower than PIM-1 membrane, but still highly permeable. The here presented self-standing and mechanically resistant blend membranes have yet a lower permeability compared to PIM-1 yet an improved CO2 solubility, which eventually will translate in higher CO2/N2 selectivity. These promising preliminary results will allow us to select and optimize the best performing PIM-1/ILs blends to develop outstanding membranes for an improved gas separation technology.

High-flux CO2 separation using thin-film composite polyether block amide membranes fabricated by transient-filler treatment

An energy-efficient and eco-friendly membrane-based CO2 separation process is required to address global concerns pertaining to energy and environment. In this context, polymer materials such as polyimides, polyvinyl alcohol, and polyether block amide (PEBA) have been intensively explored, and a high CO2 selectivity has been attained; however, these membranes exhibit a low permeance, thereby hindering process efficiency. Gas permeance depends mainly on the thickness and morphology of the selective layer; but it is difficult to overcome the limitation of the intrinsic permeability of the polymer material by controlling the thickness of the selective layer. Herein, we report a method for manufacturing thin-film composite (TFC) membranes with a defect-free, ultrathin, and highly permeable selective layer through transient-filler (TF) treatment consisting of blending a TF/polymer matrix and then removing the TF. Polyethylene glycol (PEG), used as the TF, was homogeneously blended through hydrogen bonding with the polymer matrix, PEBA. The blended membrane, PEG/PEBA, possessed a less crystalline structure than that of PEBA and a large free volume, thereby exhibiting a high gas permeance. After the removal of the TF from PEG/PEBA, the resultant PEBA (r-PEBA) retained the less crystalline structure, and the thickness of the selective layer decreased substantially. The permeance of the r-PEBA TFC membrane, 2371 GPU, was substantially higher than that of neat PEBA, 1350 GPU, owing to the aforementioned synergistic effects.

Fabrication of High-Performance Colorimetric Membrane by Incorporation of Polydiacetylene into Polyarylene Ether Nitriles Electrospinning Nanofibrous Membranes.

Polyarylene ether nitrile (PEN) is a novel high-performance engineering plastic with various applications, particularly in thermoresistance-required fields. In this study, a well-known stimuli-response polydiacetylene monomer, 10, 12-pentacosadiynoic acid (PCDA), was encapsulated within electrospun PEN nanofibers to fabricate a colorimetric membrane with satisfactory thermal and corrosion resistance. To optimize the compatibility with PCDA, two PENswith distinct molecular chains were utilized: PEN-PPL and PEN-BPA. The chemical structure and elemental mapping analysis revealed that the PCDA component was successfully incorporated into the PEN fibrous. The PCDA bound significantly better to the PEN-PPL than to the PEN-BPA; due to the carboxyl groups present on the side chains of PEN-PPL, the surface was smooth and the color changed uniformly as the temperature rose. However, owing to its poor compatibility with PEN-BPA, the PCDA formed agglomerations on the fibers. The thermal analysis demonstrated that the membranes obtained after PCDA compounding maintained their excellent heat resistance. The 5% weight loss temperatures of composite nanofibrous membranes manufactured by PEN-PPL and PEN-BPA were 402 °C and 506 °C, respectively, and their glass transition temperatures were 219 °C and 169 °C, respectively, indicating that the blended membranes can withstand high temperatures. The evaluation of application performance revealed that the composite membranes exhibited good dimensional stability upon high thermal and corrosive situations. Specifically, the PEN-P-PCDA did not shrink at 170 °C. Both composite membranes were dimensionally stable when exposed to the alkali aqueous solution. However, PEN-P-PCDA is more sensitive to OH-, exhibiting color transition at pH > 8, whereas PEN-B-PCDA exhibited color transition at high OH- concentrations (pH ≥ 13), with enhanced alkali resistance stability owing to its nanofibrous architecture. This exploratory study reveals the feasibility of PEN nanofibers functionalized using PCDA as a desirable stimulus-response sensor even in high-temperature and corrosive harsh environments.

Ni-Zn metal-organic framework based membranes for rejection of Pb(II) ions

The present paper describes a sustainable and affordable supply of clean, and safe water approach to investigate Ni-Zn MOF embedded membrane for rejection of Pb (II) ions in aqueous solution. Ni-Zn MOF powder was prepared by solvo-thermal method, and then the Ni-Zn MOF embedded membranes with various concentrations (0.025 wt%, 0.05 wt% and 0.1 wt%). The membranes were fabricated by a common phase inversion method. Phase solutions of Pb(II) prepared with PVP at different concentrations in aqueous solutions. Water filtration and Pb (II) rejection tests were operated on a batch scale. The prepared Ni-Zn MOF powder characterized by FTIR, SEM-EDX analyses and zeta potential measurements. Ni-Zn MOF membranes were characterized by FTIR, SEM-EDX analysis, contact angle, and water permeability measurements. The effects of important parameters on adsorption including concentration and pH were investigated. The obtained results indicated that the maximum rejection of Pb(II) was 98% for a feed solution containing 80 mg Pb/L at pH 8 and assistance with 2 % PVP for 0.05 wt% Ni-Zn MOF membrane. Additionally, it was detected that blend membranes revealed better Pb(II) rejection than pure PSF membrane.

Membranes Based on PTMSP/PVTMS Blends for Membrane Contactor Applications.

In this work, perspective polymeric materials were developed for membrane contactor applications, e.g., for the dissolved oxygen removal from amine CO2 capture solvents. Several polymeric blends based on poly[1-trimethylsilyl-1-propyne] (PTMSP) and poly[vinyltrimethylsilane] (PVTMS) were studied. The gas and water vapor sorption and permeability coefficients for the PTMSP/PVTMS blend membranes at different PVTMS contents (0-100%) were obtained under temperatures of 30 and 60 °C for the first time. As the PVTMS content increases, the O2 and CO2 permeabilities decrease by 160 and 195 times at 30 °C, respectively. The fractional accessible volume of the polymer blends decreases accordingly. The transport of the CO2 capture solvent vapors through the PTMSP/PVTMS blend membranes were determined in thermo-pervaporation (TPV) mode using aqueous monoethanolamine (30%), N-methyldiethanolamine (40%), and 2-amino-2-methyl-1-propanol (30%) solutions as model amine solvents at 60 °C. The membranes demonstrated high pervaporation separation factors with respect to water, resulting in low amine losses. A joint analysis of the gas permeabilities and aqueous alkanolamine TPV data allowed us to conclude that the polymer blend composition of PTMSP/PVTMS 70/30 provides an optimal combination of a sufficiently high oxygen permeability and the pervaporation separation factor at a temperature of 60 °C.

Preparation and Characterization of Nanofibrous Membranes Electro-Spun from Blended Poly(l-lactide-co-ε-caprolactone) and Recombinant Spider Silk Protein as Potential Skin Regeneration Scaffold.

Biomaterial scaffolding serves as an important strategy in skin tissue engineering. In this research, recombinant spider silk protein (RSSP) and poly(L-lactide-co-ε-caprolactone) (PLCL) were blended in different ratios to fabricate nanofibrous membranes as potential skin regeneration scaffolds with an electro-spinning process. Scanning electron microscopy (SEM), water contact angles measurement, Fourier transform infrared (FTIR) spectroscopy, wide angle X-ray diffraction (WAXD), tensile mechanical tests and thermo-gravimetric analysis (TGA) were carried out to characterize the nanofibrous membranes. The results showed that the blending of RSSP greatly decreased the nanofibers' average diameter, enhanced the hydrophilicity, changed the microstructure and thermal properties, and could enable tailored mechanical properties of the nanofibrous membranes. Among the blended membranes, the PLCL/RSSP (75/25) membrane was chosen for further investigation on biocompatibility. The results of hemolysis assays and for proliferation of human foreskin fibroblast cells (hFFCs) confirmed the membranes potential use as skin-regeneration scaffolds. Subsequent culture of mouse embryonic fibroblast cells (NIH-3T3) demonstrated the feasibility of the blended membranes as a human epidermal growth factor (hEGF) delivery matrix. The PLCL/RSSP (75/25) membrane possessed good properties comparable to those of human skin with high biocompatibility and the ability of hEGF delivery. Further studies can be carried out on such membranes with chemical or genetic modifications to make better scaffolds for skin regeneration.

High-Performance and Low-Cost Membranes Based on Poly(vinylpyrrolidone) and Cardo-Poly(etherketone) Blends for Vanadium Redox Flow Battery Applications

Energy storage systems have aroused public interest because of the blooming development of intermittent renewable energy sources. Vanadium redox flow batteries (VRFBs) are the typical candidates owing to their flexible operation and good cycle durability. However, due to the usage of perfluorinated separator membranes, VRFBs suffer from both high cost and serious vanadium ions cross penetration. Herein, we fabricate a series of low-budget and high-performance blend membranes from polyvinylpyrrolidone (PVP) and cardo-poly(etherketone) (PEKC) for VFRB. A PEKC network gives the membrane excellent mechanical rigidity, while PVP endows the blend membranes with superior sulfonic acid uptake owing to the present N-heterocycle and carbonyl group in PVP, resulting in low area resistance. Meanwhile, blend membranes also display low vanadium ion permeability resulting from the electrostatic repulsion effect of protonated PVP polymer chains towards vanadium ions. Consequently, the 50%PVP-PEKC membrane has a high ionic selectivity of 1.03 × 106 S min cm−3, while that of Nafion 115 is nearly 17 times lower (6.03 × 104 S min cm−3). The VRFB equipped with 50%PVP-PEKC membrane has high coulombic efficiencies (99.3–99.7%), voltage efficiencies (84.6–67.0%) and energy efficiencies (83.9–66.8%) at current densities of 80–180 mA cm−2, and possesses excellent cycle constancy, indicating that low-cost x%PVP-PEKC blend membranes have a great application potentiality for VRFBs.

Antimicrobial dual ionic‐covalent k‐carrageenan/carboxymethyl chitosan membranes with robust moisture retention property

AbstractTo develop an antimicrobial membrane for wound healing, the blended k‐carrageenan (KC)/carboxymethyl chitosan (CMCH) membranes were fabricated through a freeze‐drying process together with a dual‐ion (Cu2+and K+ or Cu2+and Ca2+) crosslinking approach. The dual‐ion crosslinking by Cu2+and K+ could not only make the membranes compact but could also improve the uptake capacity and mechanical properties of the fabricated membranes. The maximum tensile stress of membranes reached up to 43 MPa and the highest swelling ratio was around 5500%, exhibiting robust moisture retention property. The CMCH and Cu2+ in blended membranes provided a good antimicrobial property against gram‐positive and gram‐negative bacteria. Moreover, the fabricated membranes showed good cytocompatibility. These results indicated the fabricated KC/CMCH membranes with dual‐ion by Cu2+ and K+ have favorable properties and have a great potential for application in wound healing.

Fabrication of novel hydrophobic electrospun nanofiber membrane using polybenzoxazine for membrane distillation application

In this study, a novel hydrophobic blend polyvinylidene fluoride (PVDF) nanofibrous membrane with polybenzoxazine (PBz) was fabricated by the electrospinning technique to apply in membrane distillation (MD) process. Accordingly, pristine PVDF and a fluoro containing benzoxazine monomer (Bz) was blended and then thermally treated for crosslinking the Bz. The membrane properties were determined in terms of contact angle, young module, thickness, and the membranes were characterized by scanning electron microscope and Fourier transform infrared spectroscopy. The water contact angle of membranes increased from ca. 102.8° for the pristine PVDF membrane to 132.7° post cured Bz blended membrane. Moreover, the mechanical properties of blended membranes enhanced, while obtaining smoother and physically more stable membranes compared to the pristine nanofibrous membrane. The optimum membranes were tested in a lab-scale vacuum assisted air gap membrane distillation system. Results showed that Bz blended and cured membranes exhibited higher rejections and permeate flux for reverse osmosis brine and boron solutions compared to the pristine membrane that demonstrate the promising potential of Bz blended membranes in MD applications.

Cellulose acetate/polyvinylidene fluoride based mixed matrix membranes impregnated with UiO-66 nano-MOF for reverse osmosis desalination

Reverse osmosis (RO) is considered a lifesaver technology to conquer the current catastrophic water shortage situation. However, reaching a competitive RO membrane is a challenging issue. Therefore, this study investigated the optimum polymeric blending ratio between cellulose acetate (CA) and polyvinylidene fluoride (PVDF) to have a new blended polymeric membrane named cellulose acetate polyvinyl (CAPV-X), where X is the PVDF concentration %, with enhanced properties. The optimum prepared CA/PVDF blended membrane was selected for further enhancement with nano sized metal organic framework (UiO-66 MOF). Selection was made depending on each membrane salt rejection. A membrane characterization was performed based on Fourier transform infrared (FTIR), X-ray diffractometer (XRD), scanning electron microscope, thermal gravimetric analysis, and contact angle. FTIR and XRD data confirmed the successful preparation of the blended polymeric membranes CAPV-5, CAPV-7 and CAPV-10. Further, they proved UiO-66 nanofiller impregnation in the hybrid CA/PVDF/UiO-66 membrane (CPU). The addition of PVDF and nano-MOF had a slight positive effect on the membrane thermal stability. The contact angle increased with increasing the PVDF concentration and decreased once more with the impregnation of UiO-66. The RO membrane performance revealed that the optimum CA/PVDF ratio was found to be 93/7% with around 80% salt rejection and a permeate water flux of 4 L/m2 h. CPU composite membrane was then fabricated to enhance salt rejection and permeate water flux. The testing data indicated that salt rejection and permeate water flux increased over blended CAPV-7 membrane by almost 12% and 42%, respectively. Overall, CPU hybrid membrane could be used for water desalination with a good salt rejection of 90.2% and a permeate water flux of 5.7 L/m2 h.Graphical abstract

Novel pyrazole-based MOF synergistic polymer of intrinsic microporosity membranes for high-efficient CO2 capture

Advanced membranes with high gas separation performances are highly demanded for energy-efficient CO2 capture. Nonetheless, the ubiquitous “trade-off” relation between permeability and selectivity remains a daunting challenge for currently synthetic membranes. Here, a novel category of pyrazole-based MOF (termed as MOF-303 or Al(OH)HPDC) as nanofillers was firstly blended into the polymer of intrinsic microporosity (PIM-1) matrix to fabricate MOF-303/PIM-1 mixed matrix membranes (MMMs). Owing to their superiorities of CO2-philic ability, high porosity and suitable aperture sizes, the presence of MOF-303 in membrane could create additional CO2 transport nanochannels, thus promoting the rapid transport of CO2 molecules across the blended membrane. As a result, this newly-developed membrane containing 10 wt% MOF-303 nanofilles evince a remarkably high CO2 permeability of 6602.8 Barrer, with a comparably ideal CO2/N2 selectivity of 25.6. This corresponding separation performance far surpasses the most popular 2008 Robeson's upper bond, and approaches the refined 2019 Robeson's upper bond. This study may provide a novel avenue to apply pyrazole-based MOFs in fabricating the facilitated transport membranes applied in industrial CO2 capture.

Effect of coagulation bath on selective separation of PEI-PEG1000 methane dehydration membrane

In order to prepare high-performance natural gas dehydration membranes, effects of coagulation bath were studied during a non-solvent-induced phase separation (NIPS) process. Specifically, concentrations of N-methyl-2-pyrrolidone (NMP) and polyethylene glycol 1000 (PEG 1000) were investigated respectively on the structure and properties of polyetherimide (PEI)-PEG1000 blend membranes. Studies have shown that both coagulation baths, namely, NMP and PEG1000, can affect membrane structures and improve the overall separation performance of the blend membranes. The presence of NMP in the coagulation bath formed a dissolution equilibrium with the membrane to modify the membrane structure and slow down the rate of phase separation, and the separation coefficient was 151.8 with 8% NMP. With the increase of PEG1000 concentration in the coagulation bath, the hydrophilicity of the membrane enhanced, and a separation coefficient of 585.7 was reached at 10% PEG1000.

A highly promoted nanofiltration membrane by incorporating of aminated Zr-based MOF for efficient salts and dyes removal with excellent antifouling properties

Nowadays, effective removal of dye and salt from aqueous solutions has received widespread attention in the field of wastewater treatment. In this study, Zr-based nanofillers were used to create high-flux polyethersulfone nanofiltration membranes with impressive anti-fouling performance. Three different levels of UiO-66-NH2 concentration (0.01, 0.1, 1 wt%) were used in membrane body. Solvothermal method was used to synthesize the nanoparticles, and their physical and chemical characteristics were examined through FTIR, XRD, EDAX, and FESEM analyses. Membranes properties also were investigated by SEM, porosity, water content, roughness, water contact angle, flux, separation efficiency, and fouling studies. The surface roughness of the blended membrane with 0.01 wt% nanoparticles (M2) was almost halved compared to the pristine membrane (M1). The water contact angle was also reduced from 70.98° for M1 to 39.09° for M2. The water flux of M2 with 0.01 wt% nanoparticles was 2.31 times higher than that of the pristine membrane. The MB, RhB, and RB21 dyes, as well as Na2SO4, MgSO4, MgCl2, and NaCl solutions, were used to investigate the membrane separation efficiency. All modified membranes showed significant dye retention for both cationic and anionic dyes, and sodium sulfate rejection reached up to> 93.2%. The M2 exhibited the best performance for removal of MB (95.8%), RhB (94.2%), and RB21 (83.6%). The FRR was 46.51% for bare membrane, whereas it was increased significantly for the modified samples up to> 86%. The total resistance of the optimal membrane was remarkably reduced compared to the PES pristine membrane.