Synthesis Of Membranes Research Articles

Synthesis, Characterization, and Fabrication of Nickel Metal-Organic Framework-Incorporated Polymer Electrolyte Membranes for Fuel-Cell Applications.

Proton-conducting sulfonated polymer metal-organic framework (MOF)-based composite membranes were synthesized by anchoring the nickel MOF (Ni-MOF) to the aromatic sulfonated polymer backbone. In this work, we sulfonated two different polymers, poly(1,4-phenylene ether ether sulfone) (PEES) and poly ether ether ketone (PEEK), with a controllable sulfonation degree, and the synthesized Ni-MOF was incorporated into the sulfonated polymers to prepare a polymer electrolyte membrane. The effect of an MOF as a pendant moiety on the polymer backbone had a significant effect on properties such as water uptake, thermal, mechanical, and oxidative stabilities, swelling ratio, ion-exchange capacity (IEC), morphology, proton conductivity, and fuel-cell performance. The presence of an MOF structure enhanced the water retention capacity of the composite membranes. Adding Ni-MOF to the composite membrane improved the fuel-cell performance by increasing the OCV and power density. Among the synthesized electrolytes, the 3 wt % Ni-MOF-incorporated sPEEK membrane displayed a power density of 319 mW/cm2 with a cell voltage of 0.79 V, which was higher than the pure sulfonated polymer. Thus, the developed composite membranes are suitable for fuel-cell applications.

Synthesis and characterization of composite membranes based on bacterial cellulose and coral powder

Preparation of bacterial cellulose and coral powder composite membranes has been carried out. Composite membranes were made by mixing bacterial cellulose with coral powder at different mass ratios at temperatures of 25 ºC, 40 ºC, 60 ºC and At 80 ºC, the composite membrane was evaluated for Fourier Transformation of Infrared, X-Ray Diffraction, degree of swelling, proton conductivity and methanol permeability. From the FT-IR analysis it was found that in the absorption area around 1461.385 – 911cm-1 showing the Si-O-Si stretching functional group, and in the absorption area around 3000 - 3500 cm-1 showing the (O-H) group which shows the semicrystalline composite membrane for each mass variation, according to the results of X-Ray Diffraction. The maximum proton conductivity has been measured as 3.32 x 10-3 S.cm-1 at 60°C, produces a degree of swelling of 31.14% and methanol permeability of 3.72 × 10-9 mol/cm.s for a mass ratio of bacterial cellulose:coral powder composite membrane 4:1.

Synthesis of Chitosan Silica Membrane from Petung Bamboo (<i>Dendrocalamus asper</i>) Leaves and Its Application as Pb(II) Metallic Adsorbent

Membrane synthesis through a phase inversion method using chitosan and sodium silicate solutions has been conducted. This research aims to characterize the silica chitosan membrane (SCM) of petung bamboo leaves and determine the synthesized product's adsorption capacity for Pb(II) ions. The XRF characterization showed the silica content of petung bamboo leaves with a percentage of 78.03%. SEM analysis before adsorption is around 13.0 μm, and the pore diameter after adsorption is around 9.7 μm. The results of adsorption analysis of Pb(II) metal using AAS showed that the SCM variation A at an initial concentration of 10.0000 ppm Pb(II) metal adsorbed was 9.8101 ppm, and at an initial concentration of 25.0000 ppm Pb(II) metal was 22.3421 ppm. The variation B at an initial concentration of 10.0000 ppm Pb(II) metal adsorbed was 9.8870 ppm and at an initial concentration of 25.0000 ppm Pb(II) metal adsorbed was 23.5806 ppm. The variation C at an initial concentration of 10.0000 ppm Pb(II) metal adsorbed was 9.9639 ppm, and at an initial concentration of 25.0000 ppm Pb(II) metal was 24.1855 ppm. The results of this research conclude that the highest SCM adsorption power is variation C (2%:22.95%) with a percentage of 99.63%.

Ionic liquid-containing polymer including membrane for the removal of cobalt: Synthesis, adsorption, transport, and modeling studies

This work describes synthesis of polymer inclusion membranes (PIMs), which is prepared by using varying ratios of polyvinylidene fluoride co-hexafluorophosphate (PVDF-HFP) as the base polymer and trioctyldodecylphosphonium bis(2,4,4-trimethylpentyl)phosphinate) (P88812BTMPP) as extractant carrier, and its utilization for the Co(II) sorption and transport. PIM with 40 wt% ionic liquid content showed a high sorption efficiency (>95 %) for 100 mg/L Co(II) feed with 0 and 5 mol/L HCl. Likewise, the transport experiment was achieved with Co(II) in 5 mol/L HCl as feed solution and 2 mol/L H2SO4, which exhibited excellent performance with a recovery factor of more than 85 %. The effect of various parameters on the efficiency of Co(II) sorption and transport was examined systematically. The kinetic and thermodynamic studies revealed that Co(II) sorption onto PIM was chemisorption in nature. Interestingly, the adsorption mechanism of Co(II) was found to be dependent upon the HCl concentration, resulting in two different mode of sorption mechanisms. Moreover, Co(II) desorption (>95 %) was achieved effectively, using 2 mol/L H2SO4. The recycling experiments suggested that PIM could be reused effectively without significant performance loss after six consecutive sorption-stripping cycles. Therefore, the reported PIM holds a good potential as a sorbent of critical metals, such as cobalt, due to its cost-effectiveness, excellent performance in batch-sorption and continuous transport processes, as well as good regeneration properties. To the best of our knowledge, this is the first report on Co(II) transport, employing a membrane transport system with a novel phosphonium-based ionic liquid.

Optimized preparation route for polyamide top-coated forward osmosis membrane for enhanced water flux using industrial wastewater as feed.

The forward osmosis (FO) process has recently gained significant interest in treating wastewater, brackish/seawater and concentrating feedstocks for various operations, including desalination. The study investigates the effect of different synthesis conditions of the polyamide-based thin-film composite (TFC) FO membranes on the membranes' final performance. Taguchi statistical analyses were used to fabricate and optimize the polyamide TFC FO membrane. The process parameters as factors were the amount of polyethersulfone (PES), polyethylene glycol 400 (PEG-400), polyvinyl pyrrolidone (PVP), m-phenylenediamine (MPD), and trimesoyl chloride (TMC), and TMC reaction-time (RT). The Taguchi method was adopted to investigate the optimal conditions and the significance of individual factors using an L16 (45) orthogonal array. Another Taguchi analysis (Taguchi 2) was adopted to investigate the influence of other important parameters like optimal conditions for MPD, TMC, and TMC reaction-time factors using an L9 (33) orthogonal array. Confirmation tests validated a maximum water flux of 46.4 ± 2.32 L/m2·h with a specific combination of control factors for membrane synthesis: PES/PEG/PVP/MPD/TMC/TMC RT-16/7/0.5/1/0.05/30. These tests demonstrated a high-water flux of 7.05 ± 0.35 L/m2·h when exposed to industrial wastewater (secondary effluent) as the feed solution (FS) and fertilizer as the draw solution (DS) in the FO process. The R2 values were more than 90%. The experimental validation confirmed the models' predictive ability with different FSs, including industrial wastewater.

Synthesis of sandwich structure forward osmosis membrane with calcium-carboxyl modified polyamide and tannic acid-Fe3+ interlayer and its application in coconut water concentration

In this study, a sandwich structure thin-film composite forward osmosis (TFC-FO) membrane based on calcium-carboxyl interfacial polymerization was synthesized using tannic acid-Fe (TA-Fe) as the interlayer. Additionally, the concentration effect of Ca2+ surface modification, TA-Fe intermediate layers, and their combination on coconut water concentration, membrane efficiency, anti-fouling ability, and quality of the concentrate was investigated. Compared to the TFC-Ca or TFC-TA-Fe membrane, the TFC-TA-Fe-Ca membrane significantly enhanced the concentration effect and reverse salt flux (p < 0.05) and exerted the lowest attenuation of permeability. Furthermore, the total soluble solids content increased from 5.13 °Brix to 13.17 °Brix after 8 h. The TFC-TA-Fe-Ca membrane showed a 61.20 % increase in its efficiency compared to the TFC membrane. The total reducing sugar, acids, and polyphenol contents increased by 1.72, 1.34, and 1.22 times, respectively. Overall, the sandwich structure FO membrane exhibited significant feasibility and potential for industrial application in fruit juice concentrate production.

Room temperature aqueous synthesis of defect-engineered MOF-801 membrane towards efficient nanofiltration

Room temperature (RT) aqueous preparation of MOF membranes is of significant interest in meeting the demands of sustainability. Nevertheless, there remains no report on RT aqueous synthesis of water-stable high-valence MOF membranes to date. In this study, we developed a one-step RT protocol for fabricating defect-engineered MOF-801 membrane in aqueous media. Owing to enhanced structural hydrophilicity and enlarged micropore size, water was enabled to diffuse through the membrane with higher permeation flux. Obtained membrane exhibited exceptional dye rejection rate (CR:99.75 %, MB:99.69 % and MG:99.41 %) and unprecedented water flux (CR:77.33 L m−2 h−1·bar−1, MB:71.43 L m−2 h−1·bar−1 and MG:81.28 L m−2 h−1·bar−1), which were superior to state-of-the-art 3D pure MOF membranes. Our protocol paves a promising way towards sustainable production of water-stable MOF membranes under mild conditions.

Divergent Synthesis of Bipolar Membranes Combining Strong Interfacial Adhesion and High-Rate Capability

Divergent Synthesis of Bipolar Membranes Combining Strong Interfacial Adhesion and High-Rate Capability

Synthesis and characterization of faujasite zeolite membrane for selective enrichment of Arthrobacter sp. in synthetic wastewater.

This paper centers on the preparation and characterization of both a clay support and a faujasite zeolite membrane. Additionally, the study explores the development of bacterial media to assess the performance of these prepared membranes. The faujasite zeolite membrane was created using the hydrothermal method, involving the deposition of a faujasite layer to fine-tune the pore sizes of the clay support. The clay supports were crafted from clay which was sieved to particle size Φ ≤ 63 μm, and compacted with 3.0 wt.% activated carbon, then sintered at 1,000 °C. Distilled water fluxes revealed a decrease from 1,500 L m-2 h-1 to a minimum of 412 L m-2 h-1 after 180 min of filtration. Both membranes were characterized by XRF, XRD, FTIR, adsorption-desorption of nitrogen (N2), and SEM-EDS. PCR technique was used for the identification of the isolated Arthrobacter sp., and the retention of the bacteria on the clay support and the faujasite zeolite membrane were found to be 96 and 99%, respectively. The results showed that the faujasite zeolite membrane passed the clay support due to a narrow pore size of the faujasite zeolite membrane of 2.28 nm compared to 3.55 nm for the clay supports.

Synthesis of composite membranes modified with graphene oxide and polyethylene glycol for the removal of emerging contaminants from water

Graphene oxide (GO) incorporation of the polymer matrix of membranes can provide properties such as great durability, resistance, and reduction of fouling. In turn, polyethylene glycol (PEG) is a polymer capable of increasing the porosity and flow of membranes. The study aimed to analyze the synthesis of composite membrane polysulfone (PSF), GO and PEG, to separate caffeine, diclofenac sodium, and amoxicillin dispersed in water. It observed an increase in roughness through the incorporation of GO and its reduction with the addition of PEG. Membrane permeability increased from 0.61 L m-2 h-1 bar-1 to 4.54 L m-2 h-1 bar-1 after the addition of GO and PEG. The water permeance of the synthesized membranes reached 37.81 L m-2 h-1 bar-1. It is concluded that the structure and porosity, as well as the rejection of contaminants, were directly influenced by the incorporation of materials added to the membranes. The charge of GO contributed to structural and mechanical improvements of the membranes, reaching rejections of up to 80.61% of caffeine, 66.03% of diclofenac sodium, and 87.33% of amoxicillin with the membrane containing 1.5% of GO, being thus, it is considered promising for applications in water contaminated by emerging contaminants. The study brings real contributions to the area of membranes by developing an improved material, especially as it presents a high rejection of emerging contaminants that are still little studied.

Synthesis and characterization of mixed matrix membranes with graphene oxide‐impregnated zeolitic imidazolate framework‐8 for enhanced CO2/CH4 separation

AbstractFor the in situ growth method, the reaction time is important because increasing the reaction time may make it possible for the crystallized ZIF‐8 to fully cover the GO sheets; the excess of ZIF‐8 particles reduces the aspect ratio of the GO sheet. The reaction time will significantly change the morphology, affecting the composite's ability to absorb selective gas and, in turn, affect the gas selectivity. The present work identifies the reaction time for in situ growth of ZIF‐8 nanoparticles on GO sheets. The composite was synthesized at different reaction times of 2, 4, 6, and 8 h and incorporated into the PSF matrix. The fabricated membranes were characterized by FTIR, TGA, SEM, and XRD. The novel synthesized reaction time (6 h) was identified for better enhancement of CO2/CH4 separation. For pure gas studies, the results investigated that the CO2 permeability and CO2/CH4 selectivity were increased by 223% and 98%, respectively, compared with plain PSF membrane. In mixed gas (CO2/CH4) studies, the CO2 permeability and CO2CH4 selectivity were increased by 349% and 854%, respectively, compared with plain PSF membrane. Hence, the in situ growth method helps synthesize MOF@GO composites in the application of gas separation.

Facile Synthesis of Dual-Functional Cross-Linked Membranes with Contact-Killing Antimicrobial Properties and Humidity-Response.

Poly(2-hydroxyethylmethacrylate-co-2-(dimethylamino)ethyl methacrylate), P(HEMA-co-DMAEMAx), copolymers were quaternized through the reaction of a part of (dimethylamino)ethyl moieties of DMAEMA units with 1-bromohexadecane. Antimicrobial coatings were further prepared through the cross-linking reaction between the remaining DMAEMA units of these copolymers and the epoxide ring of poly(N,N-dimethylacrylamide-co-glycidyl methacrylate), P(DMAm-co-GMAx), copolymers. The combination of P(HEMA-co-DMAEMAx)/P(DMAm-co-GMAx) copolymers not only enabled control over quaternization and cross-linking for coating stabilization but also allowed the optimization of the processing routes towards a more facile cost-effective methodology and the use of environmentally friendly solvents like ethanol. Careful consideration was given to achieve the right content of quaternized units, qDMAEMA, to ensure antimicrobial efficacy through an appropriate amphiphilic balance and sufficient free DMAEMA groups to react with GMA for coating stabilization. Optimal synthesis conditions were achieved by membranes consisting of cross-linked P(HEMA78-co-DMAEMA9-co-qDMAEMA13)/P(DMAm-co-GMA42) membranes. The obtained membranes were multifunctional as they were self-standing and antimicrobial, while they demonstrated a distinct fast response to changes in humidity levels, widening the opportunities for the construction of "smart" antimicrobial actuators, such as non-contact antimicrobial switches.

Reusable saturated synthesis solutions for compact zeolite membranes

Zeolite membranes have excellent application prospects in the separation of mixtures with molecular-level differences; however, the uneven distribution of active ingredients on the support causes defects in the zeolite membranes, limiting their industrial applications. In this study, compact NaX and NaA zeolite membranes with perfect pervaporation performance were prepared in reusable saturated membrane synthesis solutions. These saturated membrane synthesis solutions not only provided sufficient Si/Al components for the even growth of zeolite on the support, but also reduced the random deposition of zeolite particles on the support by reducing the formation of zeolite particles in the bulk solution, improving the quality of the resulting zeolite membranes. The separation factors of the obtained NaA and NaX zeolite membranes were greater than 10000 for the water/ethanol and methanol/MTBE mixtures, respectively. Moreover, the saturated synthesis solutions could be reused multiple times to synthesize zeolite membranes after nutrient supplementation, saving resources and reducing environmental pollution. This study presents reusable solutions for synthesizing compact zeolite membranes, promoting the development of membrane technology for environmental protection and energy conservation.

One-step synthesis of freestanding and translucent ZrO2 nanotube membranes by direct electrochemical anodization

One-step synthesis of freestanding zirconium oxide nanotube (ZrO2-NT) membranes was obtained by direct electrochemical anodization of zirconium (Zr) substrates in aqueous electrolytes (mixture of 1 M (NH4)2SO4 and 0.75 M NH4F). The maximum membrane area was 9 cm2 and showed translucency from 400 to 700 nm. The ZrO2-NTs have an external diameter of ∼80 nm, an internal diameter of ∼55 nm, and a length of ∼22.5 μm. Moreover, the ZrO2-NTs showed a cubic crystal structure after anodization. The results are highly promising for applications requiring independent ZrO2 nanotube membranes.

One step co-sintering synthesis of asymmetric metal membrane with smooth surface for microfiltration

In this paper, a novel fabrication method for manufacturing tubular micro-filtration membrane with mirror-like surface by one step co-sintering without additive doping has been developed. The result shows that the metallic membrane was bonded to the support tightly after sintering at 1250 °C for 2 h. The fine powder content has a significant impact on the integrity of the membrane layer, which is due to the synergistic shrinkage during the co-sintering process. The surface roughness and average pore size of the as-fabricated stainless-steel membranes by the new method are 178 nm and 2.1 μm, respectively.

Nanoparticle-filled oriented nanofiber membrane for effective emulsion separation via spin coating

Patterned membranes, particularly those modified with nanoparticles, are commonly used in the effective filtration separation of emulsions. However, the conventional fabrication methods are based on wet spinning that require large quantities of organic solvents, necessitating treatment and recycling. This increases the economic and environmental cost, damages the environment, and lowers the production efficiency. In this study, we develop a novel spin-coating method to directly fabricate oriented and patterned nanofiber membranes from powders without harsh solution treatment. The patterned nanofiber membrane exhibits a higher flux than a traditional porous membrane with disordered nanofibers and the same retention rate. The use of oriented nanofiber membranes filled with multi-walled carbon nanotubes and graphene enhances the emulsion-breaking effect during emulsion separation. The effect of the type and diameter of the nanofibers on the orientation degradation of the oriented nanofiber membrane is analyzed. The combination of nanofiber membranes with nanoparticles enables the design and synthesis of composite nanofiber membranes with precisely tailored pore structures for various applications.

A Zn/Cd/Ni Metal-Organic Framework-Based Solid and Flexible Fluoroprobes for Highly Selective Detection of 4-Nitroaniline in Real Water Samples.

The combination of diazabicyclic compound i.e. 1,4-diazabicyclo[2.2.2]octane (DABCO) and dicarboxylate linker 1,4-dicarboxylic acid are employed to self-assemble with three divalent metal ions such as Zn2+, Cd2+, Ni2+ led to the formation of highly stable pillar layered luminescent metal-organic frameworks. The emissive response of as-synthesized MOFs was studied in organic solvents with different functionalities resulting in the development of fluoroprobes having excellent recognition ability for 4-nitroaniline with detection limit upto micromolar. All the MOFs display a good linear relation between the fluorescence intensity and concentration of 4-NA in the range of 10-90µmol L-1. The values of Ksv for Zn-MOF, Cd-MOF, and Ni-MOF are found to be 1.75 × 104mol-1L, 1.25 × 104mol-1L, and 28.0 × 104mol-1L, respectively. The calculated detection limit values are 19.7µmol L-1, 27.6µmol L-1, and 1.19µmol L-1 respectively. Moreover, the study was further extended to fabricate the solid membrane-based fluoroprobe using a linear chitosan polysaccharide and act as an efficient solid fluoroprobe for the detection of 4-NA. This proposed synthesis of polymeric membrane facilitates the MOF@chitosan fluorophore to transfer its fluorescence-emissive nature to a solid state.

Proteo-transcriptomic profiles reveal key regulatory pathways and functions of LDHA in the ovulation of domestic chickens (Gallus gallus)

BackgroundIn poultry, the smooth transition of follicles from the preovulatory-to-postovulatory phase impacts egg production in hens and can benefit the poultry industry. However, the regulatory mechanism underlying follicular ovulation in avians is a complex biological process that remains unclear.ResultsCritical biochemical events involved in ovulation in domestic chickens (Gallus gallus) were evaluated by transcriptomics, proteomics, and in vitro assays. Comparative transcriptome analyses of the largest preovulatory follicle (F1) and postovulatory follicle (POF1) in continuous laying (CL) and intermittent laying (IL) chickens indicated the greatest difference between CL_F1 and IL_F1, with 950 differentially expressed genes (DEGs), and the smallest difference between CL_POF1 and IL_POF1, with 14 DEGs. Additionally, data-independent acquisition proteomics revealed 252 differentially abundant proteins between CL_F1 and IL_F1. Perivitelline membrane synthesis, steroid biosynthesis, lysosomes, and oxidative phosphorylation were identified as pivotal pathways contributing to ovulation regulation. In particular, the regulation of zona pellucida sperm-binding protein 3, plasminogen activator, cathepsin A, and lactate dehydrogenase A (LDHA) was shown to be essential for ovulation. Furthermore, the inhibition of LDHA decreased cell viability and promoted apoptosis of ovarian follicles in vitro.ConclusionsThis study reveals several important biochemical events involved in the process of ovulation, as well as crucial role of LDHA. These findings improve our understanding of ovulation and its regulatory mechanisms in avian species.

Polyvinyl Alcohol/Zr-based Metal Organic Framework Mixed-matrix Membranes Synthesis and Application for Hydrogen Separation

Membrane gas separation is an environmentally friendly and economical method used to separate valuable gases, industrial process gas wastes, and carbon dioxide from mixed gases. The most important part of this method is the membranes. Gas separation membranes are expected to have high separation and permeability performance, high mechanical strength, easy and fast production capability, and low prices. Polymer-based membranes are mostly preferred depending on the ease of modification capability. In this study, a zirconium-based metal organic framework (Zr-MOF, MIL-140 A) was synthesized and used as a filler within polyvinyl alcohol (PVA) matrix for the selective separation of hydrogen (H2) from carbon dioxide (CO2). The effect of MIL-140 A addition on the mechanical, structural, and morphological properties of PVA was evaluated. The MIL-140 A significantly improved the mechanical strength of the membrane. According to the gas separation results, the increasing concentration of MIL-140 A increased the selective separation performance of the nanocomposite membrane. The highest mechanical strength (43.1 MPa) and best film-forming ability were obtained with 3 wt% MIL-140 A loaded membrane. The ideal H2/CO2 selectivity and hydrogen permeability were obtained as 5.6 and 944 Barrer, respectively at 2 bar feed pressure and room temperature. The highest ideal H2/CO2 selectivity was obtained as 6.3 with the H2 permeability of 959 Barrer when the MIL-140 A ratio was 4 wt%.

Layer-by-layer Assembly of Nanosheets with Matching Size and Shape for More Stable Membrane Structure than Nanosheet-Polymer Assembly.

Layer-by-layer (LbL) assembly of oppositely charged materials has been widely used as an approach to make two-dimensional (2D) nanosheet-based membranes, which often involves 2D nanosheets being alternately deposited with polymer-based polyelectrolytes to obtain an electrostabilized nanosheet-polymer structure. In this study, we hypothesized that using 2D nanosheets with matching physical properties as both polyanions and polycations may result in a more ordered nanostructure with better stability than a nanosheet-polymer structure. To compare the differences between nanosheet-nanosheet vs nanosheet-polymer structures, we assembled negatively charged molybdenum disulfide nanosheets (MoS2) with either positively charged graphene oxide (PrGO) nanosheets or positively charged polymer (PDDA). Using combined measurements by ellipsometer and quartz crystal microbalance with dissipation, we discovered that the swelling of MoS2-PrGO in ionic solutions was 60% lower than that of MoS2-PDDA membranes. Meanwhile, the MoS2-PrGO membrane retained its permeability upon drying, whereas the permeability of MoS2-PDDA decreased by 40% due to the restacking of MoS2. Overall, the MoS2-PrGO membrane demonstrated a better filtration performance. Additionally, our X-ray photoelectron spectroscopy results and analysis on layer density revealed a clearer transition in material composition during the LbL synthesis of MoS2-PrGO membranes, and the X-ray diffraction pattern suggested its resemblance to an ordered, layer-stacked structure. In conclusion, the MoS2-PrGO membrane made with nanosheets with matching size, shape, and charge density exhibited a much more aligned stacking structure, resulting in reduced membrane swelling under high salinity solutions, controlled restacking, and improved separation performance.