Статті в журналах: "Single layer membranes"

1

Loza, Sergey, Natalia Loza, Natalia Kutenko, and Nikita Smyshlyaev. "Profiled Ion-Exchange Membranes for Reverse and Conventional Electrodialysis." Membranes 12, no. 10 (October 11, 2022): 985. http://dx.doi.org/10.3390/membranes12100985.

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Profiled ion-exchange membranes are promising for improving the parameters of reverse electrodialysis due to the reduction of pumping power and electrical resistance. The smooth commercial heterogeneous cation-exchange MK-40 and anion-exchange MA-41 membranes were chosen as the initial membranes. Profiled membranes with three different types of surface profiles were obtained by hot pressing the initial membranes. The bilayer membranes were made on the basis of single-layer profiled membranes by casting MF-4SK film on the profiled surfaces. The diffusion permeability of all types of single-layer and bilayer profiled membranes was higher than of the initial ones due to the appearance of large defects on their surface during pressing. The conductivity of the profiled membrane was lower in the diluted solution and higher in the concentrated solution than of the initial one for all samples except for the bilayer anion-exchange membrane. The conductivity of that sample was lower than that of the initial anion-exchange MA-41 membrane over the entire range of studied concentrations. The counter-ion transport numbers for all studied membranes were calculated based on the concentration dependences of conductivity and diffusion permeability of the membrane by the microheterogeneous model. The selectivity of single layer and bilayer profiled membranes became lower after their profiling due to the increase of the solution phases of membranes. The asymmetry of the current-voltage curves for all single-layer and bilayer profiled membranes was found. The application of the single layer and bilayer profiled membranes in reverse electrodialysis did not lead to an increase in power density.

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2

Boztepe, Inci, Stephen Gray, Jianhua Zhang, and Jun-De Li. "Performance modelling of direct contact membrane distillation using a hydrophobic/hydrophilic dual-layer membrane." Journal of Water Reuse and Desalination 11, no. 3 (June 17, 2021): 490–507. http://dx.doi.org/10.2166/wrd.2021.072.

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Abstract HFP-co-PVDF/N6 hydrophobic/hydrophilic dual-layer membrane was used to study desalination with direct contact membrane distillation (DCMD). A one-dimensional (1-D) model was proposed to predict the flux and thermal efficiency. Heat and mass transfer equations were solved numerically for the combined hydrophilic and hydrophobic layers. The membrane characteristics of the hydrophobic layer were considered for the calculation of the mass transfer coefficients, while the hydrophilic layer was ignored since it was assumed to be filled with water. However, the hydrophilic layer was taken into account during the calculations of conductive heat transfer. Therefore, the equations are different, compared to single-layer hydrophobic membranes. It was found that with the same hydrophobic membrane characteristics, the single-layer membranes performed with better flux and thermal efficiency than the dual-layer membranes. Furthermore, the improvement of flux and thermal efficiency by an addition of the hydrophilic layer has not been observed experimentally, and it is suggested that the improved performance for dual-layer membranes reported previously is due to improved permeability by using thinner and more porous hydrophobic layers that can be mechanically reinforced by the hydrophilic layer. The validation of the model was conducted by comparing the experimental results for single- and dual-layer membranes with the modelling results. The predicted flux and thermal efficiency by the modelling were within 10% error to the experimental results.

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3

Niestroj-Pahl, Robert, Lara Stelmaszyk, Ibrahim M. A. ElSherbiny, Hussein Abuelgasim, Michaela Krug, Christian Staaks, Greta Birkholz, et al. "Performance of Layer-by-Layer-Modified Multibore® Ultrafiltration Capillary Membranes for Salt Retention and Removal of Antibiotic Resistance Genes." Membranes 10, no. 12 (December 6, 2020): 398. http://dx.doi.org/10.3390/membranes10120398.

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Polyether sulfone Multibore® ultrafiltration membranes were modified using polyelectrolyte multilayers via the layer-by-layer (LbL) technique in order to increase their rejection capabilities towards salts and antibiotic resistance genes. The modified capillary membranes were characterized to exhibit a molecular weight cut-off (at 90% rejection) of 384 Da. The zeta-potential at pH 7 was −40 mV. Laboratory tests using single-fiber modified membrane modules were performed to evaluate the removal of antibiotic resistance genes; the LbL-coated membranes were able to completely retain DNA fragments from 90 to 1500 nt in length. Furthermore, the pure water permeability and the retention of single inorganic salts, MgSO4, CaCl2 and NaCl, were measured using a mini-plant testing unit. The modified membranes had a retention of 80% toward MgSO4 and CaCl2 salts, and 23% in case of NaCl. The modified membranes were also found to be stable against mechanical backwashing (up to 80 LMH) and chemical regeneration (in acidic conditions and basic/oxidizing conditions).

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4

Wang, Luda, Christopher M. Williams, Michael S. H. Boutilier, Piran R. Kidambi, and Rohit Karnik. "Single-Layer Graphene Membranes Withstand Ultrahigh Applied Pressure." Nano Letters 17, no. 5 (April 24, 2017): 3081–88. http://dx.doi.org/10.1021/acs.nanolett.7b00442.

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5

Rodríguez-Sánchez, Ingrid Juliet, Natalia Fernanda Vergara-Villa, Dianney Clavijo-Grimaldo, Carlos Alberto Fuenmayor, and Carlos Mario Zuluaga-Domínguez. "Ultrathin single and multiple layer electrospun fibrous membranes of polycaprolactone and polysaccharides." Journal of Bioactive and Compatible Polymers 35, no. 4-5 (July 2020): 351–62. http://dx.doi.org/10.1177/0883911520944422.

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Electrospinning was used to produce fibrous membranes, in single and multiple layers, from poly(ε-caprolactone), pullulan, and from mixtures of poly(ε-caprolactone) with potato modified starch and β-glucan. It was possible to obtain single-layer membranes from solutions of pullulan in water, poly(ε-caprolactone) in chloroform, and from mixtures of poly(ε-caprolactone)/β-glucan and poly(ε-caprolactone)/potato modified starch in chloroform. Scanning electron microscopy images showed the formation of ultrathin homogeneous fibers from electrospun poly(ε-caprolactone) and pullulan, whereas the fibers obtained from mixtures of poly(ε-caprolactone)/ β -glucan and poly(ε-caprolactone)/potato modified starch had different sizes and morphologies, as well as irregular microstructures, characterized by the presence of beads. Contact angle analyses showed that pullulan membranes were extremely hydrophilic, while poly(ε-caprolactone) membranes were predominantly hydrophobic. Subsequently, poly(ε-caprolactone)-pullulan-poly(ε-caprolactone) multilayer membranes, with intermediate wettability, were prepared by successive electrospinning steps. Infrared spectroscopy and calorimetric analyses showed the presence of both polymers and the absence of changes in their structure and stability due to electrospinning, indicating adequate compatibility between the two polymers. We foresee that the polyester-polysaccharide multilayer membrane might be used as a biodegradable vehicle for active agents with different hydrophobicity, with applications as food packaging and biocompatible scaffold materials.

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6

Kawasaki, Masahiro, Hiroyuki Yoshikawa, Masato Saito, Shu Jiang, Takehiro Akeyama, Eiichi Tamiya, and Minoru Noda. "A New Type of LSPR Sensor Featuring Immobilized Liposome or Phospholipid Single Layer." Proceedings 2, no. 13 (December 4, 2018): 791. http://dx.doi.org/10.3390/proceedings2130791.

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We have fabricated a new type of LSPR sensor featuring immobilized liposome or phospholipid single layer. LSPR principally shows an ultrahigh sensitivity on surface dielectric environmental change due to interaction with target, but little has been reported so far on applying phospholipid membranes and/or liposomes as model cell membrane. We newly tried to investigate biosensing capabilities using the membranes of the both structures on Au nanostructures of LSPR sensor chip. As a result, it was confirmed that the phospholipid single layer is more effective to improve the sensitivity than the liposome. Finally, we have clearly detected 100 nM target protein of CAB and estimated a possible detection of 10 nM range from wavelength resolution by interaction with the phospholipid single layer.

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7

Shawaqfeh, Ahmad T., and Ruth E. Baltus. "Fabrication and characterization of single layer and multi-layer anodic alumina membranes." Journal of Membrane Science 157, no. 2 (May 1999): 147–58. http://dx.doi.org/10.1016/s0376-7388(98)00314-7.

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8

Drahushuk, Lee W., and Michael S. Strano. "Mechanisms of Gas Permeation through Single Layer Graphene Membranes." Langmuir 28, no. 48 (November 19, 2012): 16671–78. http://dx.doi.org/10.1021/la303468r.

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9

Yoon, Soong‐Seok, Hyun‐Kyung Lee, and Se‐Ryeong Hong. "CO2/N2 Gas Separation Using Pebax/ZIF-7—PSf Composite Membranes." Membranes 11, no. 9 (September 14, 2021): 708. http://dx.doi.org/10.3390/membranes11090708.

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In this study, we mixed the zeolitic imidazolate framework-7 (ZIF-7) with poly(ether-b-amide)® 2533 (Pebax-2533) and used it as a selective layer for a composite membrane. We prepared the composite membrane’s substrate using polysulfone (PSf), adjusted its pore size using polyethylene glycol (PEG), and applied polydimethylsiloxane (PDMS) to the gutter layer and the coating layer. Then, we investigated the membrane’s properties of gases by penetrating a single gas (N2, CO2) into the membrane. We identified the peaks and geometry of ZIF-7 to determine if it had been successfully synthesized. We confirmed that ZIF-7 had a BET surface area of 303 m2/g, a significantly high Langmuir surface area of 511 m2/g, and a high CO2/N2 adsorption selectivity of approximately 50. Considering the gas permeation, with ZIF-7 mixed into Pebax-2533, N2 permeation decreased from 2.68 GPU in a pure membrane to 0.43 GPU in the membrane with ZIF-7 25 wt%. CO2 permeation increased from 18.43 GPU in the pure membrane to 26.22 GPU in the ZIF-7 35 wt%. The CO2/N2 ideal selectivity increased from 6.88 in the pure membrane to 50.43 in the ZIF-7 25 wt%. Among the membranes, Pebax-2533/ZIF-7 25 wt% showed the highest permeation properties and the characteristics of CO2-friendly ZIF-7.

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10

Fathizadeh, Mahdi, Weiwei L. Xu, Margaret Shen, Emily Jeng, Fanglei Zhou, Qiaobei Dong, Dinesh Behera, et al. "Antifouling UV-treated GO/PES hollow fiber membranes in a membrane bioreactor (MBR)." Environmental Science: Water Research & Technology 5, no. 7 (2019): 1244–52. http://dx.doi.org/10.1039/c9ew00217k.

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11

Czymmek, Kirk J., and Karen L. Klomparens. "The ultrastructure of ascosporogenesis in freeze-substituted Thelebolus crustaceus: enveloping membrane system and ascospore initial development." Canadian Journal of Botany 70, no. 8 (August 1, 1992): 1669–83. http://dx.doi.org/10.1139/b92-206.

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High-pressure and propane-jet freezing were essential for determining the origin and development of the enveloping membrane system during ascosporogenesis in Thelebolus crustaceus. Prior to the completion of mitotic divisions within the ascus, invaginations of the plasma membrane initiated formation of the enveloping membrane system. Fusion of individual units of the closely spaced double membranes resulted in the formation of a cylinder around most of the ascus protoplasm. This double-membraned cylinder enveloped individual nuclei with accompanying cytoplasm and organelles to form ascospore initials. Envelopment of asci nuclei to form ascospore initials appeared to be facilitated by a nuclear-associated organelle and closely associated microtubule organizing center. Initially, wall materials and (or) precursors were deposited between the closely spaced double membranes from within the ascospore initials. Secondary wall formation appeared to be deposited, in part, from the epiplasm. Microtubules located adjacent to the inside wall layer of the ascospore initials appeared to contribute to an elliptical shape. Subsequent to epispore wall formation, numerous microtubules were found associated with the outer membranes of the ascospores and appeared to interconnect the spores into a single mass before discharge. Key words: Thelebolus crustaceus, ascosporogenesis, high-pressure freezing, propane-jet freezing, ultrastructure, laser scanning confocal microscopy.

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12

Park, In Kee, Dong-Hoon Lee, and Chang Hyun Lee. "Design of Electrochemically Effective Double-Layered Cation Exchange Membranes for Saline Water Electrolysis." Polymers 12, no. 9 (September 17, 2020): 2114. http://dx.doi.org/10.3390/polym12092114.

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Saline water electrolysis (SWE) is an electrochemical process to simultaneously produce hydrogen (H2), chlorine (Cl2), and sodium hydroxide (NaOH) with high purity levels (e.g., 99.999%) by applying electric power to saline water. The state-of-the art SWE membrane, Flemion®, has excellent chemical resistance to harsh SWE conditions, but still needs to lower its energy consumption by reducing its ohmic resistance to Na+ ion transport. Meanwhile, most of cation exchange membranes (CEMs) have been suffering from chemical degradation under the alkaline conditions, owing to their single layer matrices composed of sulfonic acid moieties, though they show fast Na+ ion transport behavior. Here double-layered SWE membranes were prepared on the basis of design strategies composed of the incorporation of a chemically stable carboxylic acid layer (C layer) via UV irradiation onto one surface of perfluorinated Nafion®212 membrane chosen as one of commercially available CEMs, and the thickness control of the C layer. The resulting membranes showed excellent SWE performances and improved electrochemical service life, when compared with those of Nafion®212 and Flemion®, respectively.

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13

Chin, Jing Yi, Guang Hui Teoh, Abdul Latif Ahmad, and Siew Chun Low. "Superhydrophobic surface coating on electrospun polypropylene membrane to treat high salinity water in membrane distillation." Water Science and Technology 82, no. 12 (November 5, 2020): 2948–61. http://dx.doi.org/10.2166/wst.2020.528.

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Abstract Membrane distillation (MD) is an advantageous separation process compared with pressure-driven technologies and was subsequently introduced to treat aquaculture wastewater. Harnessing a superhydrophobic membrane in an MD process is of extreme importance to prevent membrane wetting. In this work, the electrospun polypropylene (PP) membrane was surface modified by depositing an additional coating of PP via the solvent-exchange method, thereby improving the membrane's superhydrophobicity. Layer-by-layer deposition of PP caused the formation of uniform polymer spherulites on the membrane surface, which levelled up the membrane's surface roughness. A superhydrophobic surface was achieved by applying a single-layered PP coating, with static water contact angle of 152.2° and sliding angle of 12.5°. While all membranes achieved almost perfect salt rejection (up to 99.99%), the MD permeate flux improved by 30%, average of 13.0 kg/m2h, when the single-layered PP-coated membrane was used to treat the high salinity water in both 2 and 60 hr MD processes. Further layers of coating resulted in larger size of PP spherulites with higher sliding angle, followed by lowered flux in MD. The evenness of the surface coating and the size of the aggregate PP spherulites (nano-scaled) are two predominant factors contributing to the superhydrophobicity character of a membrane.

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14

Li, Chao, Liping Wen, Xin Sui, Yiren Cheng, Longcheng Gao, and Lei Jiang. "Large-scale, robust mushroom-shaped nanochannel array membrane for ultrahigh osmotic energy conversion." Science Advances 7, no. 21 (May 2021): eabg2183. http://dx.doi.org/10.1126/sciadv.abg2183.

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The osmotic energy, a large-scale clean energy source, can be converted to electricity directly by ion-selective membranes. None of the previously reported membranes meets all the crucial demands of ultrahigh power density, excellent mechanical stability, and upscaled fabrication. Here, we demonstrate a large-scale, robust mushroom-shaped (with stem and cap) nanochannel array membrane with an ultrathin selective layer and ultrahigh pore density, generating the power density up to 22.4 W·m−2 at a 500-fold salinity gradient, which is the highest value among those of upscaled membranes. The stem parts are a negative-charged one-dimensional (1D) nanochannel array with a density of ~1011 cm−2, deriving from a block copolymer self-assembly; while the cap parts, as the selective layer, are formed by chemically grafted single-molecule–layer hyperbranched polyethyleneimine equivalent to tens of 1D nanochannels per stem. The membrane design strategy provides a promising approach for large-scale osmotic energy conversion.

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15

Tincu, B., M. Avram, A. Avram, O. Tutunaru, V. Tucureanu, A. Matei, T. Burinaru, F. Comanescu, and I. Demetrescu. "Progress and control in development of single layer graphene membranes." Vacuum 175 (May 2020): 109269. http://dx.doi.org/10.1016/j.vacuum.2020.109269.

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16

Meyer, J. C., A. K. Geim, M. I. Katsnelson, K. S. Novoselov, D. Obergfell, S. Roth, C. Girit, and A. Zettl. "On the roughness of single- and bi-layer graphene membranes." Solid State Communications 143, no. 1-2 (July 2007): 101–9. http://dx.doi.org/10.1016/j.ssc.2007.02.047.

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17

Boutilier, Michael S. H., Doojoon Jang, Juan-Carlos Idrobo, Piran R. Kidambi, Nicolas G. Hadjiconstantinou, and Rohit Karnik. "Molecular Sieving Across Centimeter-Scale Single-Layer Nanoporous Graphene Membranes." ACS Nano 11, no. 6 (June 13, 2017): 5726–36. http://dx.doi.org/10.1021/acsnano.7b01231.

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18

Berned-Samatán, Víctor, Carlos Téllez, and Joaquín Coronas. "Double-Layered Pebax® 3533/ZIF-8 Membranes with Single-Walled Carbon Nanotube Buckypapers as Support for Gas Separation." Membranes 13, no. 1 (January 6, 2023): 71. http://dx.doi.org/10.3390/membranes13010071.

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Single-walled carbon nanotube buckypapers (SWCNT-bps) coated with a metal–organic framework ZIF-8 layer were used as supports for the preparation of Pebax® 3533 TFC membranes by both phase inversion and spin coating techniques. Upon proper characterization of the materials by X-ray diffraction, IR spectroscopy, thermogravimetry and electron microscopy, the obtained membranes were tested in gas separation experiments with a 15:85 CO2/N2 mixture. These experiments proved that the ZIF-8 layer prevented from the penetration of the polymer selective film into the SWCNT-bp support, giving rise to a highly permeable selective membrane. The optimum membrane was achieved by the spin-coating method, with better permeation results than that prepared by the phase inversion method, obtaining a CO2 permeance of 566 GPU together with a CO2/N2 selectivity of 20.9.

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19

Nguyen, Chinh Thanh, and Ali Beskok. "Charged nanoporous graphene membranes for water desalination." Physical Chemistry Chemical Physics 21, no. 18 (2019): 9483–94. http://dx.doi.org/10.1039/c9cp01079c.

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20

Karim, Syed Shujaat, Sarah Farrukh, Arshad Hussain, Tayyaba Noor, and Mohammad Younas. "A comprehensive overview of dual-layer composite membrane for air (O₂/N₂) separation." Polymers and Polymer Composites 29, no. 9_suppl (October 19, 2021): S1630—S1640. http://dx.doi.org/10.1177/09673911211045852.

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The separation of air (O2/N2) via a polymeric membrane has recently piqued the interest of academic researcher as well as the industrial sector. Because of its remarkable characteristics, the polymeric membrane has emerged as one of the innovative and fast growing technology. However, two major problems faced by membrane technology, which hinder its growth in the commercial sector are, 1): The trade-off between permeability and selectivity. 2): Maintaining physical and chemical structural stability in a long-term commercial scale process. Recent advancements in membrane material, structural, and process design have enabled the development of dual-layer composite (DLC) membranes. This concept combines the benefits of both thinner mixed matrix membranes (MMMs) based active layer and porous support substrate. Due to these properties, the membrane exhibits higher perm-selectivity with enhanced mechanical strength as compared to single layer polymeric membrane. This review article mainly focused on the developmental progress of DLC membrane throughout the years. In which membrane structural details, selection criteria, fabrication methodologies, application [e.g., air (O2/N2) separation] were critically reviewed. In addition, challenges arising in the DLC membrane production and future prospects for the development of these membranes were also thoroughly discussed in this literature. This creates a paradigm for future research in the commercial development of these membranes for the air (O2/N2) separation process, which can be utilized in both medical and industrial sectors. [Formula: see text]

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21

Gaálová, Jana, Mahdi Bourassi, Karel Soukup, Tereza Trávníčková, Daniel Bouša, Swati Sundararajan, Olga Losada, Roni Kasher, Karel Friess, and Zdeněk Sofer. "Modified Single-Walled Carbon Nanotube Membranes for the Elimination of Antibiotics from Water." Membranes 11, no. 9 (September 21, 2021): 720. http://dx.doi.org/10.3390/membranes11090720.

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The hydrophilic and hydrophobic single-walled carbon nanotube membranes were prepared and progressively applied in sorption, filtration, and pertraction experiments with the aim of eliminating three antibiotics—tetracycline, sulfamethoxazole, and trimethoprim—as a single pollutant or as a mixture. The addition of SiO2 to the single-walled carbon nanotubes allowed a transparent study of the influence of porosity on the separation processes. The mild oxidation, increasing hydrophilicity, and reactivity of the single-walled carbon nanotube membranes with the pollutants were suitable for the filtration and sorption process, while non-oxidized materials with a hydrophobic layer were more appropriate for pertraction. The total pore volume increased with an increasing amount of SiO2 (from 743 to 1218 mm3/g) in the hydrophilic membranes. The hydrophobic layer completely covered the carbon nanotubes and SiO2 nanoparticles and provided significantly different membrane surface interactions with the antibiotics. Single-walled carbon nanotubes adsorbed the initial amount of antibiotics in less than 5 h. A time of 2.3 s was sufficient for the filtration of 98.8% of sulfamethoxazole, 95.5% of trimethoprim, and 87.0% of tetracycline. The thicker membranes demonstrate a higher adsorption capacity. However, the pertraction was slower than filtration, leading to total elimination of antibiotics (e.g., 3 days for tetracycline). The diffusion coefficient of the antibiotics varies between 0.7–2.7 × 10−10, depending on the addition of SiO2 in perfect agreement with the findings of the textural analysis and scanning electron microscopy observations. Similar to filtration, tetracycline is retained by the membranes more than sulfamethoxazole and trimethoprim.

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Semenov, Alexander, and Irina Nyrkova. "Adsorption of Wormlike Chains onto Partially Permeable Membranes." Polymers 15, no. 1 (December 22, 2022): 35. http://dx.doi.org/10.3390/polym15010035.

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Reversible adsorption of a single stiff wormlike macromolecule to flat membranes with various permeabilities is considered theoretically. It is shown that the adsorbed layer microstructure is significantly different from either a flexible chain or a stiff chain adsorption at a solid surface. Close to the critical point, the adsorbing wormlike chain forms a strongly anisotropic proximal layer near the membrane in addition to a nearly isotropic distal layer. The proximal layer is characterized by the algebraic monomer concentration profile, c(x)∝x−β, due to the self-similar distribution of aligned polymer loops. For a perfectly penetrable membrane, β=1 which is different from β=4/3 obtained for semiflexible chain adsorption at a solid surface. Moreover, we establish that the critical exponent for a partially permeable membrane depends on its properties (porosity w) and propose an asymptotically exact theory (based on the generalized Edwards equation) predicting this dependence, β=β(w). We also develop a scaling theory elucidating, in particular, an intricate competition of loops and tails in both proximal and distal sublayers.

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23

Salpavaara, T., T. Joki, A. Skogberg, M. T. Calejo, J. Lekkala, S. Narkilahti, and P. Kallio. "Microfabricated porous SU-8 membranes as innervation interfaces for hiPSC-neurons in microfluidic devices." Journal of Physics Communications 5, no. 11 (November 1, 2021): 115003. http://dx.doi.org/10.1088/2399-6528/ac314d.

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Abstract In this study, we developed microfabricated porous membranes aimed at facilitating innervation in 3D cell culture models. The aim of the paper is to introduce a fabrication method for porous membranes with adjustable size, shape and location of the pores without obstructing imaging or the connectivity of the cells. The method is based on making a patterned SU-8 layer on a sacrificial aluminium layer by UV lithography and releasing it with etching. With the proposed method, we were able to produce single-layer self-supporting membranes that were used as interfaces in compartmentalized microfluidic devices. The functionality of the membranes and their cytocompatibility were tested by culturing human pluripotent stem cell (hPSC)-derived neurons on their surfaces. In vitro experiments demonstrated that a dense neural network develops on top of the proposed membranes within a week. Neurites were able to migrate through the pores to the bottom side of the membranes. We achieved partial, but still significant, axonal isolation. The results of this study will pave the way for the development of optimized innervated tissue models by using the combination of porous SU-8 membrane substrates, microelectrode arrays and hPSC-derived neurons in compartmentalized cell cultivation devices.

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24

Chogani, A., A. Moosavi, and M. Rahiminejad. "Numerical Simulation of Salt Water Passing Mechanism Through Nanoporous Single-Layer Graphene Membrane." Chemical Product and Process Modeling 11, no. 1 (March 1, 2016): 73–76. http://dx.doi.org/10.1515/cppm-2015-0068.

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Abstract In recent years carbon nanotubes and other carbon nanostructures such as graphene sheets have attracted a lot of attention due to their unique mechanical, thermal and electrical properties. These structures can be used in desalination of sea water, removal of hazardous substances from water tanks, gases separation, and so on. The nanoporous single layer graphene membranes are very efficient for desalinating water due to their very low thickness. In this method, water-flow thorough the membrane and salt rejection strongly depend on the applied pressure and size of nanopores that are created in graphene membrane. In this study, the mechanism of passing water and salt ions through nanoporous single-layer graphene membrane are simulated using classical molecular dynamics. We examined the effects of applied pressure and size of nanopores on desalination performance of NPG membrane. Unlike previous researches, we considered the flexibility of the membrane. The results show that by increasing the applied pressure and diameter of the nanopores, water-flow through membrane increases, meanwhile salt rejection decreases.

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25

Liu, Hao, Li Li Zhu, Yan Fang Xu, Xu Jie, and Bo Wen Cheng. "Fabrication of PMMA Membranes with Nano-Pillars Array Using Template/Spin-Coating Method." Journal of Nano Research 45 (January 2017): 84–94. http://dx.doi.org/10.4028/www.scientific.net/jnanor.45.84.

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Template/spin-coating method was presented for fabricating single-layer nano-pillar array polymethylmethacrylate (SL-PMMA) and double-layer nano-pillar array polymethylmethacrylate (DL-PMMA) membranes. The different mass ratio of PMMA/DiMethyl Formamide (DMF) solution was dripped on single-layer porous anodic alumina (SL-PAA) or double-layer porous anodic alumina (DL-PAA) membrane and spun at 4000rpm speed for 30 seconds. The SL-PAA and DL-PAA membranes had been put into vacuum oven at 150°C for 2 hours, before SL-PMMA and DL-PMMA were removed. Experimental results show that the regularity degree of PAA fabricated in OAS/PAS is higher than that of PAA fabricated in PAS by two-step anodization method. The ordered pores and clear double-layer outline can be observed from the surface and cross-section FESEM images of DL-PAA membranes. When the content of PMMA in mixture solution is 20 wt%, the top shape of nano-pillars is convex, because the solution was completely filled in the pore of SL-PAA, and the length of nano-pillars is equal to the height of pore of PAA. However, the top pore amount on nano-pillars at ascending speed 20°C per minute is more than that of at ascending speed 10°C per minute. The PMMA membranes with ordered mid-hollow and porous nano-pillars will have wide application prospect in biosensors, chemical sensors, microcapsules fabrication fields due to many advantages such as simple operation, low cost, high specific surface area, etc.

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Gaffrey, Karli Ann, Saheed Bukola, Jeff Blackburn, and Bryan S. Pivovar. "Hydrogen Crossover Flux through Two-Dimensional Nanomaterials." ECS Meeting Abstracts MA2022-02, no. 41 (October 9, 2022): 1499. http://dx.doi.org/10.1149/ma2022-02411499mtgabs.

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Energy Storage and conversion devices require an ion-exchange membrane to accomplish high transmission of charge-balancing ions and separation of anode and cathode electrolytes/gases from mixing. These critical functions of membranes play a pivotal role in ensuring device optimum performance and higher efficiency. Most conventional membranes suffer huge ionic and molecular species cross-permeation resulting in low energy efficiency and material degradation. In this work, hydrogen permeability and proton transmission through membrane electrode assemblies (MEAs) that contain a monolayer of hexagonal boron nitride, single-layer and bi-layer graphene were investigated in a gas-phase small-scale cell and a liquid cell. We found that the hydrogen crossover flux through MEAs with 2D materials was inhibited by at least a factor of 5 as compared to the one without. Single-layer graphene and boron nitride enabled high proton transmission, but bi-layer graphene inhibited proton conduction. Defect visualization of 2D materials by chemical treatment with a low ferric chloride concentration followed by imaging using a digital microscope revealed few atomic-scale defects in graphene. These findings suggest that a monolayer of 2D material may provide good selectivity for energy conversion and storage devices by blocking species crossover while allowing high proton transmission.

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Wang, Qixiang, Hong Fang, Di Wang, Jie Wang, Nana Zhang, Bin He, and Weiming Lü. "Towards a Large-Area Freestanding Single-Crystal Ferroelectric BaTiO3 Membrane." Crystals 10, no. 9 (August 21, 2020): 733. http://dx.doi.org/10.3390/cryst10090733.

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The fabrication and transfer of freestanding single-crystal ferroelectric membranes deserve intensive investigations as to their potential applications in flexible wearable devices, such as flexible data storage devices and varied sensors in E-skin configurations. In this report, we have shown a comprehensive study approach to the acquisition of a large-area freestanding single-crystal ferroelectric BaTiO3 by the Sr3Al2O6 scarification layer method. By controlling the thickness of the BaTiO3 and Sr3Al2O6, the exposed area of the Sr3Al2O6 interlayer, and the utilization of an additional electrode La2/3Sr1/3MnO3 layer, the crack density on the freestanding BaTiO3 can be dramatically decreased from 24.53% to almost none; then, a more than 700 × 530 μm2 area high-quality freestanding BaTiO3 membrane can be achieved. Our results offer a clear and repeatable technology routine for the acquisition of a flexible large-area ferroelectric membrane, which should be instructive to other transition metal oxides as well. Our study can confidently boost flexible device fabrication based on single-crystal transition metal oxides.

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Das, Jugal K., Nandini Das, and Sibdas Bandyopadhyay. "Effect of PVP Intermediate Layer on the Properties of SAPO 34 Membrane." Advances in Materials Science and Engineering 2012 (2012): 1–7. http://dx.doi.org/10.1155/2012/650217.

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SAPO 34 zeolite membranes were prepared on a tubular mullite support. Before membrane preparation, the support surfaces were coated with seed crystals. Seeds particles were prepared by hydrothermal synthesis. Before seeding, the substrates were treated with polyvinylpyrrolidone (PVP) to orient the seeds. Both the treated and untreated supports were seeded, and membranes were synthesized on those support tubes by ex situ hydrothermal method. The PVP molecule exists in the two resonance structures. Hence the acylamino bond –N+= C–O-– acts as intermediate linker between support surface and seed surface. Due to charge interaction, the seed crystals were anchored strongly to support surface. The synthesized membranes along with seed crystals were characterized by XRD, FESEM, and EDAX analysis. The single-gas permeation with CO2and H2was investigated. Up to 5 bar of feed pressure, the permselectivity of CO2and H2was as high as 4.2.

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29

Agrawal, Kumar Varoon, Jesse D. Benck, Zhe Yuan, Rahul Prasanna Misra, Ananth Govind Rajan, Yannick Eatmon, Suneet Kale, et al. "Fabrication, Pressure Testing, and Nanopore Formation of Single-Layer Graphene Membranes." Journal of Physical Chemistry C 121, no. 26 (June 22, 2017): 14312–21. http://dx.doi.org/10.1021/acs.jpcc.7b01796.

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30

Matějka, Milan, Stanislav Krátký, Tomáš Řiháček, Alexandr Knápek, and Vladimír Kolařík. "Functional nano-structuring of thin silicon nitride membranes." Journal of Electrical Engineering 71, no. 2 (April 1, 2020): 127–30. http://dx.doi.org/10.2478/jee-2020-0019.

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AbstractThe paper describes the development and production of a nano-optical device consisting of a nano-perforated layer of silicon nitride stretched in a single-crystal silicon frame using electron beam lithography (EBL) and reactive ion etching (RIE) techniques. Procedures for transferring nanostructures to the nitride layer are described, starting with the preparation of a metallic mask layer by physical vapor deposition (PVD), high-resolution pattern recording technique using EBL and the transfer of the motif into the functional layer using the RIE technique. Theoretical aspects are summarized including technological issues, achieved results and application potential of patterned silicon nitride membranes.

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31

Kloos, Joey, Menno Houben, Johan Lub, Kitty Nijmeijer, Albert P. H. J. Schenning, and Zandrie Borneman. "Tuning the Gas Separation Performances of Smectic Liquid Crystalline Polymer Membranes by Molecular Engineering." Membranes 12, no. 8 (August 20, 2022): 805. http://dx.doi.org/10.3390/membranes12080805.

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The effect of layer spacing and halogenation on the gas separation performances of free-standing smectic LC polymer membranes is being investigated by molecular engineering. LC membranes with various layer spacings and halogenated LCs were fabricated while having a planar aligned smectic morphology. Single permeation and sorption data show a correlation between gas diffusion and layer spacing, which results in increasing gas permeabilities with increasing layer spacing while the ideal gas selectivity of He over CO2 or He over N2 decreases. The calculated diffusion coefficients show a 6-fold increase when going from membranes with a layer spacing of 31.9 Å to membranes with a layer spacing of 45.2 Å, demonstrating that the layer spacing in smectic LC membranes mainly affects the diffusion of gasses rather than their solubility. A comparison of gas sorption and permeation performances of smectic LC membranes with and without halogenated LCs shows only a limited effect of LC halogenation by a slight increase in both solubility and diffusion coefficients for the membranes with halogenated LCs, resulting in a slightly higher gas permeation and increased ideal gas selectivities towards CO2. These results show that layer spacing plays an important role in the gas separation performances of smectic LC polymer membranes.

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Beardslee, Luke A., Dimitrius A. Khaladj, and Magnus Bergkvist. "Preliminary Investigation of a Sacrificial Process for Fabrication of Polymer Membranes with Sub-Micron Thickness." MRS Proceedings 1621 (2014): 113–18. http://dx.doi.org/10.1557/opl.2014.69.

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ABSTRACTHere we present a single mask sacrificial molding process that allows ultrathin 2-dimensional membranes to be fabricated using biocompatible polymeric materials. For initial investigations, polycaprolactone (PCL) was chosen as a model material. The process is capable of creating 250-500 nm thin, through-hole PCL membranes with various geometries, pore-sizes and spatial features approaching 2.5 micrometers using contact photolithography. The technique uses a mold created from two layers of lift-off resist (LOR). The upper layer is patterned, while the lower layer acts as a sacrificial release layer for the polymer membrane. For mold fabrication, photoresist on top of the layers of lift-off resist is patterned using conventional photolithography. During development the mask pattern is transferred onto the first LOR layer and the photoresist is removed using acetone, leaving behind a thin mold. The mold is filled with a solution of the desired polymer. Subsequently, both the patterned and lower LOR layers are dissolved by immersion in an alkaline solution. The membrane can be mounted onto support structures pre-release to facilitate handling.

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Gaffrey, Karli Ann, Saheed Bukola, Jeff Blackburn, and Bryan S. Pivovar. "Hydrogen Crossover Flux through Two-Dimensional Nanomaterials." ECS Transactions 109, no. 9 (September 30, 2022): 285–94. http://dx.doi.org/10.1149/10909.0285ecst.

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Energy storage and conversion devices require an ion-exchange membrane with high transmission of charge-balancing ions and separation of anode and cathode electrolytes/gases. This ensures optimum device performance. Most conventional membranes suffer huge cross-permeation resulting in low energy efficiency and material degradation. This work investigated hydrogen permeability and proton transmission through membrane electrode assemblies (MEAs) containing a monolayer of hexagonal boron nitride and single-layer and bi-layer graphene in a gas-phase small-scale cell and a liquid cell. We found that the hydrogen crossover flux through MEAs with 2D materials was inhibited by at least a factor of 5 compared to the one without. Single-layer graphene and boron nitride enabled high proton transmission, but bi-layer graphene inhibited proton conduction. Defect visualization of 2D materials revealed few atomic-scale defects in graphene. These findings suggest that a monolayer of 2D material may provide good selectivity for energy conversion and storage devices by blocking species crossover while allowing high proton transmission.

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Micero, Alessandro, Tawheed Hashem, Hartmut Gliemann, and Aline Léon. "Hydrogen Separation Performance of UiO-66-NH2 Membranes Grown via Liquid-Phase Epitaxy Layer-by-Layer Deposition and One-Pot Synthesis." Membranes 11, no. 10 (September 27, 2021): 735. http://dx.doi.org/10.3390/membranes11100735.

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The quality assurance of hydrogen fuel for mobile applications is assessed by the guidelines and directives given in the European and international standards. However, the presence of impurities in the hydrogen fuel, in particular nitrogen, water, and oxygen, is experienced in several refueling stations. Within this work, metal-organic framework (MOF)-based membranes are investigated as a fine-purification stage of the hydrogen fuel. Three H2/N2 concentrations have been used to analyze the separation factor of UiO-66-NH2 membranes prepared using the layer-by-layer (LBL) and the one-pot (OP) synthesis methods. It is shown that the separation factor for an equimolar ratio is 14.4% higher for the LBL sample compared to the OP membrane, suggesting a higher orientation and continuity of the LBL surface-supported metal-organic framework (SURMOF). Using an equimolar ratio of H2/N2, it is shown that selective separation of hydrogen over nitrogen occurs with a separation factor of 3.02 and 2.64 for the SURMOF and MOF membrane, respectively. To the best of our knowledge, this is the highest reported performance for a single-phase UiO-66-NH2 membrane. For higher hydrogen concentrations, the separation factor decreases due to reduced interactions between pore walls and N2 molecules.

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35

Bondì, M., G. Brenci, and M. Bondì. "Presence of an Endothelioid Tubelike Structure at the Interface of the Amniotic Membranes in Twins with Single and Double Placenta. Growth Factors Involvement." Acta geneticae medicae et gemellologiae: twin research 40, no. 1 (January 1991): 91–99. http://dx.doi.org/10.1017/s0001566000006772.

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AbstractA histomorphological study of the amniotic membranes in full-term twins with double and single placenta was carried out by means of the silver impregnation staining technique suitably modified. Specimens of interface of amniotic membranes were prepared by means of sections. The constant presence of a tubelike structure was observed. Proceeding from the amniotic cavity, the following histological layers were noted: 1) single layer of amniotic cells; 2) amorphic substance with fibrocytes; 3) single layer of endothelial cells. The same order of single layer is present in the amniotic membrane of the second fetus. This tubelike structure is present only in cases of twins with double placenta. If the placenta is single with two umbilical cords, the tubelike structure is not present and only a central amorphic substance surrounded by two single layers of amniotic cells is observed, to confirm the single embryogenetic derivation (monovular). Therefore, through this histological method, we can recognize the true single placenta of twin pregnancy from the pseudosingle placenta so said for the presence of adherences of adjoining surfaces that make it appear single. On the contrary, by manual dissection it is possible to identify a twin pregnancy with two placentae. From the physiological point of view, the walls of the tubelike structure have probably the function to realize exchanges of amniotic liquids between the two fetuses, so as to obtain a balance of electrolytic ions and of intercavity pressure. Growth factors (vascular endothelial factor) are probably involved in the genesis of the endothelial tubelike structure.

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36

Maguire, Nicolas A. P., Mehrdad Ebrahimi, Rong Fan, Sabine Gießelmann, Frank Ehlen, Steffen Schütz, and Peter Czermak. "Influence of Ceramic Membrane Surface Characteristics on the Flux Behavior of a Complex Fermentation Broth." Membranes 11, no. 6 (May 28, 2021): 402. http://dx.doi.org/10.3390/membranes11060402.

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The valorization of agro-industrial residues using yeasts as biocatalysts requires efficient methods for biomass separation. Filtration with ceramic membranes is suitable for this task, however, the challenge of flux decline and the unavoidable cleaning must be taken into account. We investigated the filtration of fermentation broth and its components using tubular microfiltration and ultrafiltration membranes, and hollow-fiber ultrafiltration membranes, with cut-offs of 30 and 200 nm. The steady-state flux was limited by fouling under comparable wall shear stress conditions but increased when the wall shear stress was higher. Single-component filtration with two 30 nm tubular ultrafiltration membranes, whose average surface roughness ranged from 1.0 to 3.9 µm, showed that smoother surfaces experience less biomass fouling under more intense hydrodynamic conditions. Furthermore, we showed experimentally and by scanning electron microscopy in filtration with 30 nm tubular membranes that the thickness of the first separation layer is responsible for the degree of irreversible resistance caused by the deposition of organic material in the membrane pores. The thickness of this layer should therefore be minimized without compromising mechanical stability.

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37

Abdelrasoul, Amira, Ning Zhu та Ahmed Shoker. "Investigation on Human Serum Protein Depositions Inside Polyvinylidene Fluoride-Based Dialysis Membrane Layers Using Synchrotron Radiation Micro-Computed Tomography (SR-μCT)". Membranes 13, № 1 (16 січня 2023): 117. http://dx.doi.org/10.3390/membranes13010117.

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Hemodialysis (HD) membrane fouling with human serum proteins is a highly undesirable process that results in blood activations with further severe consequences for HD patients. Polyvinylidene fluoride (PVDF) membranes possess a great extent of protein adsorption due to hydrophobic interaction between the membrane surface and non-polar regions of proteins. In this study, a PVDF membrane was modified with a zwitterionic (ZW) polymeric structure based on a poly (maleic anhydride-alt-1-decene), 3-(dimethylamino)-1-propylamine derivative and 1,3-propanesultone. Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and zeta potential analyses were used to determine the membrane’s characteristics. Membrane fouling with human serum proteins (human serum albumin (HSA), fibrinogen (FB), and transferrin (TRF)) was investigated with synchrotron radiation micro-computed tomography (SR-μCT), which allowed us to trace the protein location layer by layer inside the membrane. Both membranes (PVDF and modified PVDF) were detected to possess the preferred FB adsorption due to the Vroman effect, resulting in an increase in FB content in the adsorbed protein compared to FB content in the protein mixture solution. Moreover, FB was shown to only replace HSA, and no significant role of TRF in the Vroman effect was detected; i.e., TRF content was nearly the same both in the adsorbed protein layer and in the protein mixture solution. Surface modification of the PVDF membrane resulted in increased FB adsorption from both the protein mixture and the FB single solution, which is supposed to be due to the presence of an uncompensated negative charge that is located at the COOH group in the ZW polymer.

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38

Nam, Yoon-Tae, Jun-Hyeok Kang, Jae-Dong Jang, Jun-Hyuk Bae, Hee-Tae Jung, and Dae-Woo Kim. "Recent Developments in Nanoporous Graphene Membranes for Organic Solvent Nanofiltration: A Short Review." Membranes 11, no. 10 (October 18, 2021): 793. http://dx.doi.org/10.3390/membranes11100793.

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Graphene-based membranes are promising candidates for efficient organic solvent nanofiltration (OSN) processes because of their unique structural characteristics, such as mechanical/chemical stability and precise molecular sieving. Recently, to improve organic solvent permeance and selectivity, nanopores have been fabricated on graphene planes via chemical and physical methods. The nanopores serve as an additional channel for facilitating ultrafast solvent permeation while filtering organic molecules by size exclusion. This review summarizes the recent developments in nanoporous graphene (NG)-based membranes for OSN applications. The membranes are categorized depending on the membrane structure: single-layer NG, multilayer NG, and graphene-based composite membranes hybridized with other porous materials. Techniques for nanopore generation on graphene, as well as the challenges faced and the perspectives required for the commercialization of NG membranes, are also discussed.

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39

Leitgeb, Markus, Christopher Zellner, Manuel Dorfmeister, Michael Schneider, and Ulrich Schmid. "Buckling Porous SiC Membranes." Proceedings 2, no. 13 (December 17, 2018): 785. http://dx.doi.org/10.3390/proceedings2130785.

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In preliminary studies it could be shown that single crystalline silicon carbide wafers can be porosified with metal assisted photochemical etching. Furthermore, the generation of porous areas which are locally defined is possible with this method. By adjusting the etching parameters, a highly porous layer (degree of porosity of 90%) can be formed which is under-etched by a line of breakage. By depositing a compressively stressed amorphous SiC:H thin film on top of a porous region, the a-SiC:H film can be locally separated from the substrate, resulting in a buckled membrane configuration. Such membranes might open up potential applications in MEMS design concepts.

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40

Attia, Hadi, Daniel J. Johnson, Chris J. Wright, and Nidal Hilal. "Comparison between dual-layer (superhydrophobic–hydrophobic) and single superhydrophobic layer electrospun membranes for heavy metal recovery by air-gap membrane distillation." Desalination 439 (August 2018): 31–45. http://dx.doi.org/10.1016/j.desal.2018.04.003.

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41

Younes, Khaled, Omar Mouhtady, Hamdi Chaouk, Emil Obeid, Rabih Roufayel, Ahmad Moghrabi, and Nimer Murshid. "The Application of Principal Component Analysis (PCA) for the Optimization of the Conditions of Fabrication of Electrospun Nanofibrous Membrane for Desalination and Ion Removal." Membranes 11, no. 12 (December 13, 2021): 979. http://dx.doi.org/10.3390/membranes11120979.

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Nowadays, acquiring a water supply for urban and industrial uses is one of the greatest challenges facing humanity for ensuring sustainability. Membrane technology has been considered cost-effective, encompasses lower energy requirements, and at the same time, offers acceptable performance. Electrospun nanofibrous membranes (ENMs) are considered a novel and promising strategy for the production of membranes that could be applied in several treatment processes, especially desalination and ion removal. In this study, we apply an unsupervised machine-learning strategy, the so-called principal component analysis (PCA), for the purpose of seeking discrepancies and similarities between different ENMs. The main purpose was to investigate the influence of membrane fabrication conditions, characteristics, and process conditions in order to seek the relevance of the application of different electrospun nanofibrous membranes (ENMs). Membranes were majorly classified into single polymers/layers, from one side, and dual multiple layer ENMs, from another side. For both classes, variables related to membrane fabrication conditions were not separated from membrane characterization variables. This reveals that membranes’ characteristics not only depend on the chemical composition, but also on the fabrication conditions. On the other hand, the process conditions of ENM fabrication showed an extensive effect on membranes’ performance.

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42

Liu, Zhaoxian, Donghui Meng, Guohua Ren, Xiao Zhang, Yan Han, Lina Wang, Wei Sun, Lichen Sun, and Rongxin Yan. "New leak elements for helium based on single-layer graphene composite membranes." Journal of Vacuum Science & Technology B 39, no. 4 (July 2021): 044202. http://dx.doi.org/10.1116/6.0001068.

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43

O’Hern, Sean C., Michael S. H. Boutilier, Juan-Carlos Idrobo, Yi Song, Jing Kong, Tahar Laoui, Muataz Atieh, and Rohit Karnik. "Selective Ionic Transport through Tunable Subnanometer Pores in Single-Layer Graphene Membranes." Nano Letters 14, no. 3 (February 13, 2014): 1234–41. http://dx.doi.org/10.1021/nl404118f.

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44

Martin, M. B., B. Dlubak, R. S. Weatherup, M. Piquemal-Banci, H. Yang, R. Blume, R. Schloegl, et al. "Protecting nickel with graphene spin-filtering membranes: A single layer is enough." Applied Physics Letters 107, no. 1 (July 6, 2015): 012408. http://dx.doi.org/10.1063/1.4923401.

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45

Zhang, Xin, and Jing-Gang Gai. "Single-layer graphyne membranes for super-excellent brine separation in forward osmosis." RSC Advances 5, no. 83 (2015): 68109–16. http://dx.doi.org/10.1039/c5ra09512c.

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46

Bukola, Saheed, Kyle Beard, Carol Korzeniewski, Joel M. Harris, and Stephen E. Creager. "Single-Layer Graphene Sandwiched between Proton-Exchange Membranes for Selective Proton Transmission." ACS Applied Nano Materials 2, no. 2 (January 15, 2019): 964–74. http://dx.doi.org/10.1021/acsanm.8b02270.

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47

SundararajanAuthors contributed equ, Narayan, Dongshin KimCurrent address: Department of B, and Andrew A. Berlin. "Microfluidic operations using deformable polymer membranes fabricated by single layer soft lithography." Lab on a Chip 5, no. 3 (2005): 350. http://dx.doi.org/10.1039/b500792p.

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48

Alharbi, Hamad F., Mustafa Y. Haddad, Muhammed Omer Aijaz, Abdulaziz K. Assaifan, and Mohammed R. Karim. "Electrospun Bilayer PAN/Chitosan Nanofiber Membranes Incorporated with Metal Oxide Nanoparticles for Heavy Metal Ion Adsorption." Coatings 10, no. 3 (March 19, 2020): 285. http://dx.doi.org/10.3390/coatings10030285.

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Bilayer nanofiber membranes with enhanced adsorption and mechanical properties were produced by combining a layer of polyacrylonitrile (PAN) functionalized with metal oxides (MO) of ZnO or TiO2 with a layer of chitosan (CS) via consecutive electrospinning. The adsorption properties of the bilayer PAN/MO–CS nanofiber membranes against lead (Pb(II)) and cadmium (Cd(II)) ions were investigated, including the effects of the solution pH, initial ion concentrations, and interaction time. The integration of a CS layer into PAN/MO nanofibers increased the adsorption capacity of lead by 102% and cadmium by 405%, compared to PAN/MO single layer. The nonlinear optimization method showed that the pseudo-second-order kinetic model and Langmuir isotherm equation better described the adsorption results. More importantly, the incorporation of a supportive CS nanofiber layer enhanced the tensile strength of PAN/MO–CS bilayer by approximately 68% compared to the PAN/MO single layer, owing to the strong interaction between the fibers at the interface of the two layers.

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49

Goh, Li May, Zhiwei Thong, Weikun Paul Li, Shu Ting Ooi, Farhanah Esa, Kok Seng Ng, Adil Dhalla, and Chakravarthy Gudipati. "Development and Industrial-Scale Fabrication of Next-Generation Low-Energy Membranes for Desalination." Membranes 12, no. 5 (May 22, 2022): 540. http://dx.doi.org/10.3390/membranes12050540.

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Spiral-wound modules have been the most common configuration of packing flat-sheet membranes since the early development of polyamide (PA) membranes for water treatment applications. Conventional spiral-wound modules (SWMs) for desalination applications typically consist of several leaf sets, with each leaf set comprising feed spacers, membranes, and a permeate carrier (PC) wrapped around a permeate-collecting tube. The membrane area that can be packed into a given module diameter is limited by the overall leaf set thickness, restricting module productivity for a given membrane permeability. We describe here a novel industrial-scale method for successfully coating the polysulfone (PSf) ultrafiltration (UF) support layer directly onto a permeate carrier, instead of conventional non-woven fabric, as a precursor to the polyamide TFC coating, resulting in twofold benefits: (a) drastically simplifying the membrane fabrication process by eliminating the use of non-woven fabric and (b) increasing the throughput of each membrane module by facilitating the packing of a larger membrane area in a standard module housing. By combining the permeate carrier and membrane into a single sheet, the need for the non-woven support layer was eliminated, leading to a significantly reduced leaf set thickness, enabling a much larger membrane area to be packed in a given volume, leading to lower energy consumption per cubic meter of produced water. Molecular-weight cutoff (MWCO) values in the range of 36–96 kDa were found to be dependent on PC thickness and material. Nevertheless, the reinforced membranes were successfully fabricated with a ~9% reduction in membrane leaf thickness compared to a conventional membrane. Preliminary trials of coating a thin-film composite PA layer resulted in defect-free reverse osmosis (RO) membranes with a salt rejection of 94% and a flux of 40 L m−2 h−1 when tested against a 2000 mg/L NaCl feed solution at an operating pressure of 15 bar. Results from the testing of the 1812 and 2514 elements validated the novel concept and paved the way for further improvements towards full-scale RO membranes with the potential to be the next low-energy workhorse of the water industry.

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50

Tang, Yuanyuan, Shan Li, Jia Xu, and Congjie Gao. "Thin Film Composite Forward Osmosis Membrane with Single-Walled Carbon Nanotubes Interlayer for Alleviating Internal Concentration Polarization." Polymers 12, no. 2 (January 23, 2020): 260. http://dx.doi.org/10.3390/polym12020260.

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This study reported a series of thin film composite (TFC) membranes with single-walled nanotubes (SWCNTs) interlayers for the forward osmosis (FO) application. Pure SWCNTs with ultrahigh length-to-diameter ratio and without any functional group were applied to form an interconnect network interlayer via strong π-π interactions. Compared to the TFC membrane without SWCNTs interlayer, our TFC membrane with optimal SWCNTs interlayer exhibited more than three times the water permeability (A) of 3.3 L m−2h−1bar−1 in RO mode with 500 mg L−1 NaCl as feed solution and nearly three-fold higher FO water flux of 62.8 L m−2 h−1 in FO mode with the deionized water as feed solution and 1 M NaCl as draw solution. Meanwhile, the TFC membrane with SWCNTs interlayer exhibited significantly reduced membrane structure parameters (S) to immensely mitigate the effect of internal concentration polarization (ICP) in support layer with micro-sized pores in favor of higher water flux. It showed that the pure SWCNTs interlayer could be an effective strategy to apply in FO membranes.

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