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Membranes, Volume 12, Issue 6 (June 2022) – 92 articles

Cover Story (view full-size image): Supported lipid bilayers (SLBs) are versatile models for studying cell membrane behavior using a variety of surface techniques. However, predominantly anionic SLBs on quartz crystals to represent the inner membrane of Gram-positive bacteria are currently not available. We report a robust method based on treating the quartz crystal with cationic aminopropyl trimethoxysilane. We found that anionic phosphatidylglycerol (PG) vesicles adsorbed and remained intact without creating a SLB, but mixed vesicles of PG with lysophosphatidylglycerol (LPG) led to stable SLBs. The dynamics of SLB formation showed that in contrast to zwitterionic lipids that display a two-step process of vesicle adsorption followed by their breakdown, the PG/LPG mixed vesicles ruptured instantaneously on contacting the quartz surface, resulting in a one-step SLB formation. View this paper
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11 pages, 3572 KiB  
Communication
Characterization of Antimicrobial Composite Edible Film Formulated from Fermented Cheese Whey and Cassava Peel Starch
by Gemilang Lara Utama, Isfari Dinika, Siti Nurmilah, Nanang Masruchin, Bambang Nurhadi and Roostita Lobo Balia
Membranes 2022, 12(6), 636; https://doi.org/10.3390/membranes12060636 - 20 Jun 2022
Cited by 6 | Viewed by 2121
Abstract
Antimicrobial composite edible film can be a solution for environmentally friendly food packaging, which can be made from fermented cheese whey containing an antimicrobial agent and cassava peel waste that contains starch. The research aims to determine the formulation of fermented cheese whey [...] Read more.
Antimicrobial composite edible film can be a solution for environmentally friendly food packaging, which can be made from fermented cheese whey containing an antimicrobial agent and cassava peel waste that contains starch. The research aims to determine the formulation of fermented cheese whey and cassava peel waste starch, resulting in an antimicrobial composite edible film with the best physical, mechanical, and water vapour permeability (WVP) properties, as well as with high antimicrobial activity. This research was conducted using experimental methods with nine composite edible film formulation treatments with three replications. Three variations in the fermented cheese whey and cassava peel starch ratio (v/v) (1:3, 1:1, 3:1) were combined with variations in the addition of glycerol (20%, 33%, 45%) (w/w) in the production of the composite edible film. Then, the physical characteristics such as elongation at break, tensile strength, WVP, colour, and antimicrobial effect of its film-forming solution were observed. The results showed that 24 h of whey fermentation with Candida tropicalis resulted in an 18.50 mm inhibition zone towards Pseudomonas aeruginosa. The best characteristic of the film was obtained from the formulation of a whey:starch ratio of 1:3 and 33% glycerol, which resulted in a thickness value of 0.21 mm, elongation at break of 19.62%, tensile strength of 0.81 N/mm2, WVP of 3.41 × 10−10·g/m·s·Pa at a relative humidity (RH) of 100%–35%, and WVP of 9.84 × 10−10·g/m·s·Pa at a RH of 75%–35%, with an antimicrobial activity towards P. aeruginosa of 5.11 mm. Full article
(This article belongs to the Special Issue Biodegradable Films Characterization and Food Packaging)
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10 pages, 2536 KiB  
Article
Role of Interleukin-6 in the Antigen-Specific Mucosal Immunoglobulin A Responses Induced by CpG Oligodeoxynucleotide-Loaded Cationic Liposomes
by Rui Tada, Emi Honjo, Shoko Muto, Noriko Takayama, Hiroshi Kiyono, Jun Kunisawa and Yoichi Negishi
Membranes 2022, 12(6), 635; https://doi.org/10.3390/membranes12060635 - 20 Jun 2022
Cited by 2 | Viewed by 1830
Abstract
An advantage of mucosal vaccines over conventional parenteral vaccines is that they can induce protective immune responses not only at mucosal surfaces but also in systemic compartments. Despite this advantage, few live attenuated or inactivated mucosal vaccines have been developed and applied clinically. [...] Read more.
An advantage of mucosal vaccines over conventional parenteral vaccines is that they can induce protective immune responses not only at mucosal surfaces but also in systemic compartments. Despite this advantage, few live attenuated or inactivated mucosal vaccines have been developed and applied clinically. We recently showed that the intranasal immunization of ovalbumin (OVA) with class B synthetic oligodeoxynucleotides (ODNs) containing immunostimulatory CpG motif (CpG ODN)-loaded cationic liposomes synergistically exerted both antigen-specific mucosal immunoglobulin A (IgA) and systemic immunoglobulin G (IgG) responses in mice. However, the mechanism underlying the mucosal adjuvant activity of CpG ODN-loaded liposomes remains unknown. In the present study, we showed that the intranasal administration of CpG ODN-loaded cationic liposomes elicited interleukin (IL)-6 release in nasal tissues. Additionally, pre-treatment with an anti-IL-6 receptor (IL-6R) antibody attenuated antigen-specific nasal IgA production but not serum IgG responses. Furthermore, the intranasal administration of OVA and CpG ODN-loaded cationic liposomes increased the number of IgA+/CD138+ plasma cells and IgA+/B220+ B cells in the nasal passages. This increase was markedly suppressed by pre-treatment with anti-IL-6R blocking antibody. In conclusion, IL-6 released by CpG ODN-loaded cationic liposomes at the site of administration may play a role in the induction of antigen-specific IgA responses by promoting differentiation into IgA+ plasma cells for IgA secretion from B cells. Full article
(This article belongs to the Special Issue Functional Analysis and Applications of Membrane Lipids)
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18 pages, 3430 KiB  
Article
Effects of Pressurized Aeration on the Biodegradation of Short-Chain Chlorinated Paraffins by Escherichia coli Strain 2
by Yongxing Qian, Wanling Han, Fuhai Zhou, Bixiao Ji, Huining Zhang and Kefeng Zhang
Membranes 2022, 12(6), 634; https://doi.org/10.3390/membranes12060634 - 19 Jun 2022
Cited by 1 | Viewed by 1834
Abstract
Short-chain chlorinated paraffins (SCCPs) were defined as persistent organic pollutants in 2017, and they can migrate and transform in the environment, accumulate in organisms, and amplify through the food chain. Although they pose a serious threat to environmental safety and human health, there [...] Read more.
Short-chain chlorinated paraffins (SCCPs) were defined as persistent organic pollutants in 2017, and they can migrate and transform in the environment, accumulate in organisms, and amplify through the food chain. Although they pose a serious threat to environmental safety and human health, there are few papers on their removal. The current SCCP removal methods are expensive, require severe operating conditions, involve time-consuming biological treatment, and have poor removal specificities. Therefore, it is important to seek efficient methods to remove SCCPs. In this paper, a pressurized reactor was introduced, and the removal performance of SCCPs by Escherichia coli strain 2 was investigated. The results indicated that moderate pure oxygen pressurization promoted bacterial growth, but when it exceeded 0.15 MPa, the bacterial growth was severely inhibited. When the concentration of SCCPs was 20 mg/L, the removal rate of SCCPs was 85.61% under 0.15 MPa pure oxygen pressurization for 7 days, which was 25% higher than at atmospheric pressure (68.83%). In contrast, the removal rate was only 69.28% under 0.15 MPa air pressure. As the pressure continued to increase, the removal rate of SCCPs decreased significantly. The total amount of extracellular polymeric substances (EPS) increased significantly upon increasing the pressure, and the amount of tightly bound EPS (TB-EPS) was higher than that of loosely bound EPS (LB-EPS). The pressure mainly promoted the secretion of proteins in LB-EPS. Furthermore, an appropriate pure oxygen pressure of 0.15 MPa improved the dehydrogenase activity. The gas chromatography–mass spectrometry (GC–MS) results indicated that the degradation pathway possibly involved the cleavage of the C–Cl bond in SCCPs, which produced Cl, followed by C–C bond breaking. This process degraded long-chain alkanes into short-chain alkanes. Moreover, the main degradation products detected were 2,4-dimethylheptane (C9H20), 2,5-dimethylheptane (C9H20), and 3,3-dimethylhexane (C8H18). Full article
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16 pages, 1080 KiB  
Review
The ESCRT Machinery: Remodeling, Repairing, and Sealing Membranes
by Yolanda Olmos
Membranes 2022, 12(6), 633; https://doi.org/10.3390/membranes12060633 - 19 Jun 2022
Cited by 21 | Viewed by 7506
Abstract
The ESCRT machinery is an evolutionarily conserved membrane remodeling complex that is used by the cell to perform reverse membrane scission in essential processes like protein degradation, cell division, and release of enveloped retroviruses. ESCRT-III, together with the AAA ATPase VPS4, harbors the [...] Read more.
The ESCRT machinery is an evolutionarily conserved membrane remodeling complex that is used by the cell to perform reverse membrane scission in essential processes like protein degradation, cell division, and release of enveloped retroviruses. ESCRT-III, together with the AAA ATPase VPS4, harbors the main remodeling and scission function of the ESCRT machinery, whereas early-acting ESCRTs mainly contribute to protein sorting and ESCRT-III recruitment through association with upstream targeting factors. Here, we review recent advances in our understanding of the molecular mechanisms that underlie membrane constriction and scission by ESCRT-III and describe the involvement of this machinery in the sealing and repairing of damaged cellular membranes, a key function to preserve cellular viability and organellar function. Full article
(This article belongs to the Special Issue Recent Studies of Plasma Membranes)
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9 pages, 528 KiB  
Article
Calculation of Lipophilicity of Organophosphate Pesticides Using Density Functional Theory
by Kurban E. Magomedov, Ruslan Z. Zeynalov, Sagim I. Suleymanov, Sarizhat D. Tataeva and Viktoriya S. Magomedova
Membranes 2022, 12(6), 632; https://doi.org/10.3390/membranes12060632 - 19 Jun 2022
Cited by 6 | Viewed by 2075
Abstract
Higher lipophilicity facilitates the passage of a substance across lipid cell membranes, the blood–brain barrier and protein binding, and may also indicate its toxicity. We proposed eight methods for predicting the lipophilicity of the 22 most commonly used organophosphate pesticides. In this work, [...] Read more.
Higher lipophilicity facilitates the passage of a substance across lipid cell membranes, the blood–brain barrier and protein binding, and may also indicate its toxicity. We proposed eight methods for predicting the lipophilicity of the 22 most commonly used organophosphate pesticides. In this work, to determine the lipophilicity and thermodynamic parameters of the solvation of pesticides, we used methods of density functional theory with various basis sets, as well as modern Grimm methods. The prediction models were evaluated and compared against eight performance statistics, as well as time and RAM used in the calculation. The results show that the PBE-SVP method provided the best of the proposed predictive capabilities. In addition, this method consumes relatively less CPU and RAM resources. These methods make it possible to reliably predict the ability of pesticide molecules to penetrate cell membranes and have a negative effect on cells and the organism as a whole. Full article
(This article belongs to the Collection Feature Papers in Membrane Surface and Interfaces)
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22 pages, 3687 KiB  
Article
Ion Separations Based on Spontaneously Arising Streaming Potentials in Rotating Isoporous Membranes
by Chao Tang, Andriy Yaroshchuk and Merlin L. Bruening
Membranes 2022, 12(6), 631; https://doi.org/10.3390/membranes12060631 - 18 Jun 2022
Cited by 7 | Viewed by 1867
Abstract
Highly selective ion separations are vital for producing pure salts, and membrane-based separations are promising alternatives to conventional ion-separation techniques. Our previous work demonstrated that simple pressure-driven flow through negatively charged isoporous membranes can separate Li+ and K+ with selectivities as [...] Read more.
Highly selective ion separations are vital for producing pure salts, and membrane-based separations are promising alternatives to conventional ion-separation techniques. Our previous work demonstrated that simple pressure-driven flow through negatively charged isoporous membranes can separate Li+ and K+ with selectivities as high as 70 in dilute solutions. The separation mechanism relies on spontaneously arising streaming potentials that induce electromigration, which opposes advection and separates cations based on differences in their electrophoretic mobilities. Although the separation technique is simple, this work shows that high selectivities are possible only with careful consideration of experimental conditions including transmembrane pressure, solution ionic strength, the K+/Li+ ratio in the feed, and the extent of concentration polarization. Separations conducted with a rotating membrane show Li+/K+ selectivities as high as 150 with a 1000 rpm membrane rotation rate, but the selectivity decreases to 1.3 at 95 rpm. These results demonstrate the benefits and necessity of quantitative control of concentration polarization in highly selective separations. Increases in solution ionic strength or the K+/Li+ feed ratio can also decrease selectivities more than an order of magnitude. Full article
(This article belongs to the Special Issue Advances in Porous and Dense Membranes: Fabrication and Applications)
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17 pages, 7388 KiB  
Article
The Design of Ternary Composite Polyurethane Membranes with an Enhanced Photocatalytic Degradation Potential for the Removal of Anionic Dyes
by Usman Zubair, Muhammad Zahid, Nimra Nadeem, Kainat Ghazal, Huda S. AlSalem, Mona S. Binkadem, Soha T. Al-Goul and Zulfiqar Ahmad Rehan
Membranes 2022, 12(6), 630; https://doi.org/10.3390/membranes12060630 - 17 Jun 2022
Cited by 3 | Viewed by 2082
Abstract
Photocatalysis is an efficient and an eco-friendly way to eliminate organic pollutants from wastewater and filtration media. The major dilemma coupled with conventional membrane technology in wastewater remediation is fouling. In this study, the photocatalytic degradation potential of novel thermoplastic polyurethane (TPU) based [...] Read more.
Photocatalysis is an efficient and an eco-friendly way to eliminate organic pollutants from wastewater and filtration media. The major dilemma coupled with conventional membrane technology in wastewater remediation is fouling. In this study, the photocatalytic degradation potential of novel thermoplastic polyurethane (TPU) based NiO on aminated graphene oxide (NH2-GO) nanocomposite membranes was explored. The fabrication of TPU-NiO/NH2-GO membranes was achieved by the phase inversion method and analyzed for their performances. The membranes were effectively characterized in terms of surface morphology, functional group, and crystalline phase identification, using scanning electron microscopy, Fourier transformed infrared spectroscopy, and X-ray diffraction analysis, respectively. The prepared materials were investigated in terms of photocatalytic degradation potential against selected pollutants. Approximately 94% dye removal efficiency was observed under optimized conditions (i.e., reaction time = 180 min, pH 3–4, photocatalyst dose = 80 mg/100 mL, and oxidant dose = 10 mM). The optimized membranes possessed effective pure water flux and excellent dye rejection (approximately 94%) under 4 bar pressure. The nickel leaching in the treated wastewater sample was determined using inductively coupled plasma-optical emission spectrometry (ICP-OES). The obtained data was kinetically analyzed using first- and second-order reaction kinetic models. A first-order kinetic study was suited for the present study. Besides, the proposed membranes provided excellent photocatalytic ability up to six reusability cycles. The combination of TPU and NH2-GO provided effective strength to membranes and the immobilization of NiO nanoparticles improved the photocatalytic behavior. Full article
(This article belongs to the Special Issue UF/NF/RO Membranes for Wastewater Treatment and Reuse)
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17 pages, 3384 KiB  
Article
High-Efficiency Water Recovery from Urine by Vacuum Membrane Distillation for Space Applications: Water Quality Improvement and Operation Stability
by Fei Wang, Junfeng Liu, Da Li, Zheng Liu, Jie Zhang, Ping Ding, Guochang Liu and Yujie Feng
Membranes 2022, 12(6), 629; https://doi.org/10.3390/membranes12060629 - 17 Jun 2022
Cited by 2 | Viewed by 1947
Abstract
Water recovery by membrane distillation (MD) is an attractive alternative to existing urine treatment systems because it could improve the water recovery rate and reliability in space missions. However, there are few studies of urine MD, particularly on the removal of the remaining [...] Read more.
Water recovery by membrane distillation (MD) is an attractive alternative to existing urine treatment systems because it could improve the water recovery rate and reliability in space missions. However, there are few studies of urine MD, particularly on the removal of the remaining contaminants from distillate water and the assessment of its long-term performance. In this study, the influences of various operation parameters on distillate water quality and operation stability were investigated in batch mode. The low pH of feedstock reduced the conductivity and total ammonium nitrogen (TAN) in distillate water because the low pH promoted the ionization of ammonia to ammonium ions. However, the low pH also facilitated the formation of free chlorine hydride, which resulted in the minor deterioration of the conductivity in the distillate due to the increasing volatility of chlorine hydride in the feedstock. Thirty batches of vacuum membrane distillation (VMD) experiments demonstrated that the permeate flux and the distillate water quality slightly decreased due to the small range of membrane wetting but still maintained an over 94.2% and 95.8% removal efficiency of the total organic carbon (TOC) and TAN, and the conductivity was <125 μs cm−1 in the distillate water after 30 test batches. VMD is a feasible option for urine treatment in space missions. Full article
(This article belongs to the Special Issue Membranes for Resource, Energy, and Water Recovery)
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18 pages, 3689 KiB  
Article
Optimal Control of Direct Contact Membrane Distillation Operated under Fluctuating Energy Source
by Emad Ali
Membranes 2022, 12(6), 628; https://doi.org/10.3390/membranes12060628 - 16 Jun 2022
Cited by 1 | Viewed by 1825
Abstract
An optimal control strategy was tested to regulate the flow rate of the cold stream to maximize the time-averaged water production of a laboratory-scale membrane distillation (MD) process. The MD process is operated under fluctuating inlet hot temperatures at a fixed flow rate [...] Read more.
An optimal control strategy was tested to regulate the flow rate of the cold stream to maximize the time-averaged water production of a laboratory-scale membrane distillation (MD) process. The MD process is operated under fluctuating inlet hot temperatures at a fixed flow rate for the hot stream. The inlet hot temperature fluctuates due to fluctuation in the supplied renewable energy source, such as solar energy. The simulation revealed the possibility of enhancing the average water production by up to 4.2%, by alternating the flow rate of the cold stream relative to a fixed flow rate of the hot stream. The enhancement was limited because, when using a long membrane, the mass flux degrades when the ratio of the cold stream to the hot stream flow rates is either very high or low. By modifying the control strategy to adapt the membrane length in addition to the flow rate of the cold stream, highly improved performance could be obtained. In fact, up to 40% enhancement in the average water production was observed. Full article
(This article belongs to the Special Issue Separation Processes in Membranes: Design, Synthesis and Applications)
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15 pages, 1889 KiB  
Article
Thermodynamic Optimization of Ammonia Decomposition Solar Heat Absorption System Based on Membrane Reactor
by Tianchao Xie, Shaojun Xia and Qinglong Jin
Membranes 2022, 12(6), 627; https://doi.org/10.3390/membranes12060627 - 16 Jun 2022
Cited by 8 | Viewed by 2016
Abstract
In this paper, an ammonia decomposition membrane reactor is applied to a solar heat absorption system, and thermodynamic optimization is carried out according to the usage scenarios. First, a model of an ammonia decomposition solar heat absorption system based on the membrane reactor [...] Read more.
In this paper, an ammonia decomposition membrane reactor is applied to a solar heat absorption system, and thermodynamic optimization is carried out according to the usage scenarios. First, a model of an ammonia decomposition solar heat absorption system based on the membrane reactor is established by using finite time thermodynamics (FTT) theory. Then, the three-objective optimization with and the four-objective optimization without the constraint of the given heat absorption rate are carried out by using the NSGA-II algorithm. Finally, the optimized performance objectives and the corresponding design parameters are obtained by using the TOPSIS decision method. Compared with the reference system, the TOPSIS optimal solution for the three-objective optimization can reduce the entropy generation rate by 4.8% and increase the thermal efficiency and energy conversion rate by 1.5% and 1.4%, respectively. The optimal solution for the four-objective optimization can reduce the heat absorption rate, entropy generation rate, and energy conversion rate by 15.5%, 14%, and 8.7%, respectively, and improve the thermal efficiency by 15.7%. The results of this paper are useful for the theoretical study and engineering application of ammonia solar heat absorption systems based on membrane reactors. Full article
(This article belongs to the Special Issue Membrane Synthesis and Progress in Membrane Reactor)
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11 pages, 2596 KiB  
Article
Antifouling Conductive Composite Membrane with Reversible Wettability for Wastewater Treatment
by Yi Li, Ruonan Gao, Jianwen Zhang, Yue Zhang and Shuai Liang
Membranes 2022, 12(6), 626; https://doi.org/10.3390/membranes12060626 - 16 Jun 2022
Cited by 5 | Viewed by 2033
Abstract
Membrane fouling severely hinders the sustainable development of membrane separation technology. Membrane wetting property is one of the most important factors dominating the development of membrane fouling. Theoretically, a hydrophilic membrane is expected to be more resistant to fouling during filtration, while a [...] Read more.
Membrane fouling severely hinders the sustainable development of membrane separation technology. Membrane wetting property is one of the most important factors dominating the development of membrane fouling. Theoretically, a hydrophilic membrane is expected to be more resistant to fouling during filtration, while a hydrophobic membrane with low surface energy is more advantageous during membrane cleaning. However, conventional membrane materials do not possess the capability to change their wettability on demand. In this study, a stainless steel mesh–sulfosuccinate-doped polypyrrole composite membrane (SSM/PPY(AOT)) was prepared. By applying a negative or positive potential, the surface wettability of the membrane can be switched between hydrophilic and relatively hydrophobic states. Systematic characterizations and a series of filtration experiments were carried out. In the reduction state, the sulfonic acid groups of AOT were more exposed to the membrane surface, rendering the surface more hydrophilic. The fouling filtration experiments verified that the membrane is more resistant to fouling in the hydrophilic state during filtration and easier to clean in the hydrophobic state during membrane cleaning. Furthermore, Ca2+ and Mg2+ could complex with foulants, aggravating membrane fouling. Overall, this study demonstrates the importance of wettability switching in membrane filtration and suggests promising applications of the SSM/PPY(AOT) membrane. Full article
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15 pages, 631 KiB  
Review
Mitochondrial Membranes and Mitochondrial Genome: Interactions and Clinical Syndromes
by Mohammed Almannai, Azza Salah and Ayman W. El-Hattab
Membranes 2022, 12(6), 625; https://doi.org/10.3390/membranes12060625 - 15 Jun 2022
Cited by 2 | Viewed by 1986
Abstract
Mitochondria are surrounded by two membranes; the outer mitochondrial membrane and the inner mitochondrial membrane. They are unique organelles since they have their own DNA, the mitochondrial DNA (mtDNA), which is replicated continuously. Mitochondrial membranes have direct interaction with mtDNA and are therefore [...] Read more.
Mitochondria are surrounded by two membranes; the outer mitochondrial membrane and the inner mitochondrial membrane. They are unique organelles since they have their own DNA, the mitochondrial DNA (mtDNA), which is replicated continuously. Mitochondrial membranes have direct interaction with mtDNA and are therefore involved in organization of the mitochondrial genome. They also play essential roles in mitochondrial dynamics and the supply of nucleotides for mtDNA synthesis. In this review, we will discuss how the mitochondrial membranes interact with mtDNA and how this interaction is essential for mtDNA maintenance. We will review different mtDNA maintenance disorders that result from defects in this crucial interaction. Finally, we will review therapeutic approaches relevant to defects in mitochondrial membranes. Full article
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11 pages, 3878 KiB  
Article
Semi-Quantitative Evaluation of Asymmetricity of Dialysis Membrane Using Forward and Backward Ultrafiltration
by Akihiro C. Yamashita, Toshiki Kakee, Takahisa Ono, Jun Motegi, Satoru Yamaguchi and Takashi Sunohara
Membranes 2022, 12(6), 624; https://doi.org/10.3390/membranes12060624 - 15 Jun 2022
Cited by 1 | Viewed by 1930
Abstract
Performance of the dialysis membrane is strongly dependent upon the physicochemical structure of the membrane. The objective of this study is to devise a new in vitro evaluation technique to quantify the physicochemical structures of the membrane. Three commercial dialyzers with cellulose triacetate [...] Read more.
Performance of the dialysis membrane is strongly dependent upon the physicochemical structure of the membrane. The objective of this study is to devise a new in vitro evaluation technique to quantify the physicochemical structures of the membrane. Three commercial dialyzers with cellulose triacetate (CTA), asymmetric CTA (termed ATA®), and polyether sulfone (PES) membranes (Nipro Co., Osaka, Japan) were employed for investigation. Forward and backward ultrafiltration experiments were performed separately with aqueous vitamin B12 (MW 1355), α-chymotrypsin (MW 25,000), albumin (MW 66,000) and dextran solutions, introducing the test solution inside or outside the hollow fiber (HF), respectively. Sieving coefficients (s.c.) for these solutes were measured under the test solution flow rate of 200 mL/min and the ultrafiltration rate of 10 mL/min at 310 K, according to the guidelines provided by Japanese academic societies. We defined the ratio of s.c. in the backward ultrafiltration to that in the forward ultrafiltration and termed it the index for asymmetricity (IA). The IA values were unity for vitamin B12 and α-chymotrypsin in all three of the dialyzers. The IA values for albumin, however, were 1.0 in CTA, 1.9 in ATA®, and 3.9 in PES membranes, respectively, which corresponded well with the fact that CTA is homogeneous, whereas ATA® and PES are asymmetrical in structure. Moreover, the asymmetricity of ATA® and PES may be different by twofold. This fact was verified in continuous basis by employing dextran solution before and after being fouled with albumin. These findings may contribute to the development of a novel membrane for improved success of dialysis therapy. Full article
(This article belongs to the Special Issue Membranes in Biomedical Engineering: Assisting Clinical Engineers)
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3 pages, 170 KiB  
Editorial
Novel Membranes for Environmental Application
by Dong Zou and Zhaoxiang Zhong
Membranes 2022, 12(6), 623; https://doi.org/10.3390/membranes12060623 - 15 Jun 2022
Viewed by 1386
Abstract
Membrane-based separations for water purification and gas separation have been applied extensively to address the global challenges of water scarcity and the pollution of aquatic and air environments [...] Full article
(This article belongs to the Special Issue Novel Membranes for Environmental Application)
3 pages, 201 KiB  
Editorial
Membranes for Gas Separation and Purification Processes
by Chong Yang Chuah
Membranes 2022, 12(6), 622; https://doi.org/10.3390/membranes12060622 - 15 Jun 2022
Cited by 2 | Viewed by 1769
Abstract
This Special Issue, entitled “Membranes for Gas Separation and Purification Processes”, was introduced to discuss the recent progress in the development of membranes for gas separation and purification [...] Full article
(This article belongs to the Special Issue Membranes for Gas Separation and Purification Processes)
11 pages, 4581 KiB  
Article
Carbon Nanotube Enhanced Filtration and Dewatering of Kerosene
by Sumona Paul, Mitun Chandra Bhoumick, Sagar Roy and Somenath Mitra
Membranes 2022, 12(6), 621; https://doi.org/10.3390/membranes12060621 - 15 Jun 2022
Cited by 6 | Viewed by 1860
Abstract
Current approaches to dewatering aviation fuel such as kerosene are adsorption by activated charcoal, gravity separation, etc. The objective of this work is to develop and demonstrate the filtration and dewatering of kerosene using a carbon nanotube immobilised membrane (CNIM). Highly hydrophobic membranes [...] Read more.
Current approaches to dewatering aviation fuel such as kerosene are adsorption by activated charcoal, gravity separation, etc. The objective of this work is to develop and demonstrate the filtration and dewatering of kerosene using a carbon nanotube immobilised membrane (CNIM). Highly hydrophobic membranes were prepared by immobilising carbon nanotube (CNTs) over polytetrafluoroethylene (PTFE) and polyvinylidene difluoride (PVDF) microfiltration membrane for the dewatering of ppm level water from kerosene. The effects of different CNT concentrations on membrane morphology, hydrophobicity, porosity, and permeability were characterised. After immobilising CNT into membranes, the contact angle increased by 9%, 16%, and 43% compared to unmodified 0.1 μm PTFE, 0.22 μm PTFE and 0.22 μm PVDF membranes, respectively. The CNIM showed remarkable separation efficiency for the fuel-water system. The micro/nano water droplets coalesced on the CNT surface to form larger diameters of water droplets detached from the membrane surface, leading to enhanced water rejection. In general, the water rejection increased with the amount of CNT immobilised while the effective surface porosity over pore length and flux decreased. PTFE base membrane showed better performance compared to the PVDF substrate. The CNIMs were fabricated with 0.1 and 0.22 μm PTFE at an optimised CNT loading of 3 and 6 wt.%, and the water rejection was 99.97% and 97.27%, respectively, while the kerosene fluxes were 43.22 kg/m2·h and 55.44 kg/m2·h respectively. Full article
(This article belongs to the Section Membrane Applications)
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11 pages, 1832 KiB  
Article
Electromembrane Extraction of Posaconazole for Matrix-Assisted Laser Desorption/Ionization Mass Spectrometric Detection
by Chi-Sheng Chen, Wen-Chi Chen and Sarah Y. Chang
Membranes 2022, 12(6), 620; https://doi.org/10.3390/membranes12060620 - 14 Jun 2022
Cited by 1 | Viewed by 1516
Abstract
A new mode of electromembrane extraction (EME) has been developed for detection via matrix-assisted laser desorption/ionization mass spectrometry (MALDI/MS). Posaconazole, extracted from 8 mL of a 10 mM trifluoroacetic acid solution onto a thin polyvinylidene difluoride (PVDF) membrane, was used as a model [...] Read more.
A new mode of electromembrane extraction (EME) has been developed for detection via matrix-assisted laser desorption/ionization mass spectrometry (MALDI/MS). Posaconazole, extracted from 8 mL of a 10 mM trifluoroacetic acid solution onto a thin polyvinylidene difluoride (PVDF) membrane, was used as a model analyte. The transport was forced by an electrical potential difference between two electrodes inside the lumen of a hollow fiber and glass tube. Under an application of 80 V, cationic posaconazole in the sample solution moved toward the negative electrode inside the glass tube and was trapped by the PVDF membrane on the side. After 15 min of extraction, 3 μL of α-cyano-4-hydroxycinnamic acid (CHCA) solution was applied on top of the membrane, which was then analyzed by MALDI/MS. Under optimal extraction conditions, the calibration curve of posaconazole was linear over a concentration range of 0.10–100.00 nM. The limit of detection (LOD) at a signal-to-noise ratio of 3 was 0.03 nM with an enhancement factor of 138 for posaconazole. The application of this method to the determination of posaconazole in human serum samples was also successfully demonstrated. Full article
(This article belongs to the Special Issue Advance in Electromembrane Technology)
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11 pages, 3105 KiB  
Communication
Notes on the Treatment of Charged Particles for Studying Cyclotide/Membrane Interactions with Dissipative Particle Dynamics
by Felix Bänsch, Christoph Steinbeck and Achim Zielesny
Membranes 2022, 12(6), 619; https://doi.org/10.3390/membranes12060619 - 14 Jun 2022
Viewed by 1817
Abstract
Different charge treatment approaches are examined for cyclotide-induced plasma membrane disruption by lipid extraction studied with dissipative particle dynamics. A pure Coulomb approach with truncated forces tuned to avoid individual strong ion pairing still reveals hidden statistical pairing effects that may lead to [...] Read more.
Different charge treatment approaches are examined for cyclotide-induced plasma membrane disruption by lipid extraction studied with dissipative particle dynamics. A pure Coulomb approach with truncated forces tuned to avoid individual strong ion pairing still reveals hidden statistical pairing effects that may lead to artificial membrane stabilization or distortion of cyclotide activity depending on the cyclotide’s charge state. While qualitative behavior is not affected in an apparent manner, more sensitive quantitative evaluations can be systematically biased. The findings suggest a charge smearing of point charges by an adequate charge distribution. For large mesoscopic simulation boxes, approximations for the Ewald sum to account for mirror charges due to periodic boundary conditions are of negligible influence. Full article
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20 pages, 2640 KiB  
Article
Extracellular Particles as Carriers of Cholesterol Not Associated with Lipoproteins
by Sergey Landa, Nicolay Verlov, Natalia Fedorova, Mikhail Filatov, Rimma Pantina, Vladimir Burdakov, Elena Varfolomeeva and Vladimir Emanuel
Membranes 2022, 12(6), 618; https://doi.org/10.3390/membranes12060618 - 14 Jun 2022
Cited by 4 | Viewed by 1957
Abstract
Exosomes and exomeres are the smallest microparticles ranging from 20 to 130 nm in diameter. They are found in almost all biological fluids. Exosomes and exomeres are of considerable interest since they can be involved in intercellular signaling and are biological markers of [...] Read more.
Exosomes and exomeres are the smallest microparticles ranging from 20 to 130 nm in diameter. They are found in almost all biological fluids. Exosomes and exomeres are of considerable interest since they can be involved in intercellular signaling and are biological markers of the state of cells, which can be used for diagnostics. The nomenclature of exosomes remains poorly developed. Most researchers try to classify them based on the mode of formation, physicochemical characteristics, and the presence of tetrasporin markers CD9, CD63, and CD81. The data presented in this work show that although exomeres carry tetrasporin biomarkers, they differ from exosomes strongly in lipid composition, especially in cholesterol content. The production of exomeres by cells is associated with the synthesis of cholesterol in cells and is expressed or suppressed by regulators of the synthesis of mevalonate, an intermediate product of cholesterol metabolism. In addition, the work shows that the concentration of extracellular particles in the body correlates with the concentration of cholesterol in the plasma, but weakly correlates with the concentration of cholesterol in lipoproteins. This suggests that not all plasma cholesterol is associated with lipoproteins, as previously thought. Full article
(This article belongs to the Special Issue Progress in Extracellular Vesicle (EV) Analysis)
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14 pages, 4809 KiB  
Article
Palladium Membrane with High Density of Large-Angle Grain Boundaries to Promote Hydrogen Diffusivity
by Efi Hadjixenophontos, Masoud Mahmoudizadeh, Michael Rubin, Dirk Ullmer, Fatemeh Razmjooei, Alexander C. Hanf, Jan Brien, Roland Dittmeyer and Asif Ansar
Membranes 2022, 12(6), 617; https://doi.org/10.3390/membranes12060617 - 14 Jun 2022
Viewed by 1813
Abstract
A higher density of large-angle grain boundaries in palladium membranes promotes hydrogen diffusion whereas small-angle grain boundaries suppress it. In this paper, the microstructure formation in 10 µm thick palladium membranes is tuned to achieve a submicronic grain size above 100 nm with [...] Read more.
A higher density of large-angle grain boundaries in palladium membranes promotes hydrogen diffusion whereas small-angle grain boundaries suppress it. In this paper, the microstructure formation in 10 µm thick palladium membranes is tuned to achieve a submicronic grain size above 100 nm with a high density of large-angle grain boundaries. Moreover, changes in the grain boundaries’ structure is investigated after exposure to hydrogen at 300 and 500 °C. To attain large-angle grain boundaries in Pd, the coating was performed on yttria-stabilized zirconia/porous Crofer 22 APU substrates (intended for use later in an ultracompact membrane reactor). Two techniques of plasma sprayings were used: suspension plasma spraying using liquid nano-sized powder suspension and vacuum plasma spraying using microsized powder as feedstock. By controlling the process parameters in these two techniques, membranes with a comparable density of large-angle grain boundaries could be developed despite the differences in the fabrication methods and feedstocks. Analyses showed that a randomly oriented submicronic structure could be attained with a very similar grain sizes between 100 and 500 nm which could enhance hydrogen permeation. Exposure to hydrogen for 72 h at high temperatures revealed that the samples maintained their large-angle grain boundaries despite the increase in average grain size to around 536 and 720 nm for vacuum plasma spraying and suspension plasma spraying, respectively. Full article
(This article belongs to the Special Issue Advances in Membrane Science for Sustainable Future)
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16 pages, 4189 KiB  
Article
Is Lipid Specificity Key to the Potential Antiviral Activity of Mouthwash Reagent Chlorhexidine against SARS-CoV-2?
by Arun K. Rathod, Chetan S. Poojari and Moutusi Manna
Membranes 2022, 12(6), 616; https://doi.org/10.3390/membranes12060616 - 14 Jun 2022
Cited by 2 | Viewed by 2124
Abstract
Chlorhexidine (CHX), a popular antibacterial drug, is widely used for oral health. Emerging pieces of evidence suggest that commercially available chlorhexidine mouthwash formulations are effective in suppressing the spread of SARS-CoV-2, possibly through destabilization of the viral lipid envelope. CHX is known for [...] Read more.
Chlorhexidine (CHX), a popular antibacterial drug, is widely used for oral health. Emerging pieces of evidence suggest that commercially available chlorhexidine mouthwash formulations are effective in suppressing the spread of SARS-CoV-2, possibly through destabilization of the viral lipid envelope. CHX is known for its membrane-active properties; however, the molecular mechanism revealing how it damages the viral lipid envelope is yet to be understood. Here we used extensive conventional and umbrella sampling simulations to quantify the effects of CHX on model membranes mimicking the composition of the SARS-CoV-2 outer lipid membrane as well as the host plasma membrane. Our results show that the lipid composition and physical properties of the membrane play an important role in binding and insertion, with CHX binding favorably to the viral membrane over the plasma membrane. Among the simulated lipids, CHX preferentially binds to anionic lipids, PS and PI, which are more concentrated in the viral membrane. The deeper and stable binding of CHX to the viral membrane results in more pronounced swelling of the membrane laterally with a thinning of the bilayer. The overall free energies of pore formation are strongly reduced for the viral membrane compared to the plasma membrane; however, CHX has a larger concentration-dependent effect on free energies of pore formation in the plasma membrane than the viral membrane. The results indicate that CHX is less toxic to the human plasma membrane at low concentrations. Our simulations reveal that CHX facilitates pore formation by the combination of thinning the membrane and accumulation at the water defect. This study provides insights into the mechanism underlying the anti-SARS-CoV-2 potency of CHX, supporting its potential for application as an effective and safe oral rinse agent for preventing viral transmission. Full article
(This article belongs to the Special Issue Capturing Dynamics of Biomolecules - from Experiments to Simulations)
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14 pages, 2000 KiB  
Article
Characterization and Interaction with Biomembrane Model of Benzo[k,l]xanthene Lignan Loaded Solid Lipid Nanoparticles
by Cristina Torrisi, Nunzio Cardullo, Vera Muccilli, Corrado Tringali, Francesco Castelli and Maria Grazia Sarpietro
Membranes 2022, 12(6), 615; https://doi.org/10.3390/membranes12060615 - 13 Jun 2022
Cited by 3 | Viewed by 1535
Abstract
Benzo[k,l]xanthene lignans are a group of rare natural products belonging to the class of polyphenols with promising biological activities and are studied as potential chemotherapeutic agents. The lipophilic character of a xanthene core makes these molecules difficult to be used in an aqueous [...] Read more.
Benzo[k,l]xanthene lignans are a group of rare natural products belonging to the class of polyphenols with promising biological activities and are studied as potential chemotherapeutic agents. The lipophilic character of a xanthene core makes these molecules difficult to be used in an aqueous medium, limiting their employment in studies for pharmaceutical applications. To overcome this problem, a drug-delivery system which is able to improve the stability and bioavailability of the compound can be used. In this study, a bioactive benzoxanthene lignan (BXL) has been included in SLN. Unloaded and BXL-loaded SLN have been prepared using the Phase Inversion Temperature method and characterized in terms of size, zeta potential, entrapment efficiency and stability. Differential scanning calorimetry was used to evaluate the thermotropic behavior and ability of SLN to act as carriers for BXL. A biomembrane model, represented by multilamellar vesicles, was used to simulate the interaction of the SLN with the cellular membrane. Unloaded and loaded SLN were incubated with the MLV, and their interactions were evaluated through variations in their calorimetric curves. The results obtained suggest that SLN could be used as a delivery system for BXL. Full article
(This article belongs to the Special Issue Recent Advances in Lipid Membranes)
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16 pages, 3614 KiB  
Article
Sensitivity of Material, Microstructure and Operational Parameters on the Performance of Asymmetric Oxygen Transport Membranes: Guidance from Modeling
by Kai Wilkner, Robert Mücke, Stefan Baumann, Wilhelm Albert Meulenberg and Olivier Guillon
Membranes 2022, 12(6), 614; https://doi.org/10.3390/membranes12060614 - 13 Jun 2022
Cited by 3 | Viewed by 1441
Abstract
Oxygen transport membranes can enable a wide range of efficient energy and industrial applications. One goal of development is to maximize the performance by the improvement of the material, microstructural properties and operational conditions. However, the complexity of the transportation processes taking place [...] Read more.
Oxygen transport membranes can enable a wide range of efficient energy and industrial applications. One goal of development is to maximize the performance by the improvement of the material, microstructural properties and operational conditions. However, the complexity of the transportation processes taking place in such commonly asymmetric membranes impedes the identification of the parameters to improve them. In this work, we present a sensitivity study that allows identification of these parameters. It is based on a 1D transport model that includes surface exchange, ionic and electronic transport inside the dense membrane, as well as binary diffusion, Knudsen diffusion and viscous flux inside the porous support. A support limitation factor is defined and its dependency on the membrane conductivity is shown. For materials with very high ambipolar conductivity the transport is limited by the porous support (in particular the pore tortuosity), whereas for materials with low ambipolar conductivity the transport is limited by the dense membrane. Moreover, the influence of total pressure and related oxygen partial pressures in the gas phase at the membrane’s surfaces was revealed to be significant, which has been neglected so far in permeation test setups reported in the literature. In addition, the accuracy of each parameter’s experimental determination is discussed. The model is well-suited to guiding experimentalists in developing high-performance gas separation membranes. Full article
(This article belongs to the Section Inorganic Membranes)
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10 pages, 288 KiB  
Article
Assessment of Processes to Increase the Useful Life and the Reuse of Reverse Osmosis Elements in Cape Verde and Macaronesia
by Tomás Tavares, Jorge Tavares, Federico A. León-Zerpa, Baltasar Peñate-Suárez and Alejandro Ramos-Martín
Membranes 2022, 12(6), 613; https://doi.org/10.3390/membranes12060613 - 13 Jun 2022
Cited by 3 | Viewed by 1985
Abstract
Reverse osmosis membranes could be reused in the same or another desalination plant by replacing the membranes in the dirtiest first positions with those in the least damaged last positions, also changing the best first stage membranes to the second and vice versa. [...] Read more.
Reverse osmosis membranes could be reused in the same or another desalination plant by replacing the membranes in the dirtiest first positions with those in the least damaged last positions, also changing the best first stage membranes to the second and vice versa. The useful life of these membranes could be extended by chemical cleaning and giving them a second life in tertiary treatment plants, as well as reusing them in industrial processes where special reverse osmosis membranes are used and degrade rapidly, in processes with leachates from landfill waste, and also an interesting option is the oxidation of reverse osmosis elements to obtain nanofiltration, ultrafiltration or microfiltration membranes for the elimination of physical dirt. The main categories of recycling by thermal processing commonly used in the industry include incineration and pyrolysis to produce energy, gas and fuel. These processes can be applied to mixed plastic waste, such as the combination of materials used in the manufacture of reverse osmosis membranes. Recycling of reverse osmosis elements from desalination plants is shown to be an opportunity, and pioneering initiatives are already underway in Europe. Energy recovery via incineration is feasible but is not considered in line with the environmental, social and political problems it may generate. However, the recycling of reverse osmosis elements via the pyrolytic industry for fuel production can be centralized in a new industry already planned in the Macaronesia area, and all obsolete osmosis membranes can be sent there. This is a technically and economically viable business opportunity with a promising future in today’s recycling market, as discussed in the article. Full article
7 pages, 453 KiB  
Article
Light Isotope Separation through the Compound Membrane of Graphdiyne
by Valentina A. Poteryaeva, Michael A. Bubenchikov and Alexey M. Bubenchikov
Membranes 2022, 12(6), 612; https://doi.org/10.3390/membranes12060612 - 13 Jun 2022
Viewed by 1269
Abstract
The separation of isotopes of one substance is possible within the framework of the quantum mechanical model. The tunneling effect allows atoms and molecules to overcome the potential barrier with a nonzero probability. The membranes of two monoatomic layers enhance the differences in [...] Read more.
The separation of isotopes of one substance is possible within the framework of the quantum mechanical model. The tunneling effect allows atoms and molecules to overcome the potential barrier with a nonzero probability. The membranes of two monoatomic layers enhance the differences in the components’ passage through the membrane, thereby providing a high separation degree of mixtures. The probability of overcoming the potential barrier by particles is found from the solving of the Schrödinger integral equation. Hermite polynomials are used to expand all the terms of the Schrödinger integral equation in a series to get a wave function. A two-layer graphdiyne membrane is used to separate the mixture. Full article
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13 pages, 1838 KiB  
Article
Chemical Vapour Deposition Graphene–PMMA Nanolaminates for Flexible Gas Barrier
by Antonio Baldanza, Maria Giovanna Pastore Carbone, Cosimo Brondi, Anastasios C. Manikas, Giuseppe Mensitieri, Christos Pavlou, Giuseppe Scherillo and Costas Galiotis
Membranes 2022, 12(6), 611; https://doi.org/10.3390/membranes12060611 - 12 Jun 2022
Cited by 3 | Viewed by 1952
Abstract
Successful ways of fully exploiting the excellent structural and multifunctional performance of graphene and related materials are of great scientific and technological interest. New opportunities are provided by the fabrication of a novel class of nanocomposites with a nanolaminate architecture. In this work, [...] Read more.
Successful ways of fully exploiting the excellent structural and multifunctional performance of graphene and related materials are of great scientific and technological interest. New opportunities are provided by the fabrication of a novel class of nanocomposites with a nanolaminate architecture. In this work, by using the iterative lift-off/float-on process combined with wet depositions, we incorporated cm-size graphene monolayers produced via Chemical Vapour Deposition into a poly (methyl methacrylate) (PMMA) matrix with a controlled, alternate-layered structure. The produced nanolaminate shows a significant improvement in mechanical properties, with enhanced stiffness, strength and toughness, with the addition of only 0.06 vol% of graphene. Furthermore, oxygen and carbon dioxide permeability measurements performed at different relative humidity levels, reveal that the addition of graphene leads to significant reduction of permeability, compared to neat PMMA. Overall, we demonstrate that the produced graphene–PMMA nanolaminate surpasses, in terms of gas barrier properties, the traditional discontinuous graphene–particle composites with a similar filler content. Moreover, we found that the gas permeability through the nanocomposites departs from a monotonic decrease as a function of relative humidity, which is instead evident in the case of the pure PMMA nanolaminate. This work suggests the possible use of Chemical Vapour Deposition graphene–polymer nanolaminates as a flexible gas barrier, thus enlarging the spectrum of applications for this novel material. Full article
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16 pages, 3432 KiB  
Article
Pilot-Scale Selective Electrodialysis for the Separation of Chloride and Sulphate from High-Salinity Wastewater
by Fuqin Li, Yanfu Guo and Shaozhou Wang
Membranes 2022, 12(6), 610; https://doi.org/10.3390/membranes12060610 - 11 Jun 2022
Cited by 8 | Viewed by 2475
Abstract
The separation of chloride and sulphate is important for the treatment of high salt wastewater, and monovalent selective electrodialysis (MSED) has advantages in terms of energy consumption and pre-treatment costs compared to nanofiltration salt separation. Most of the research on monovalent anion-selective membranes [...] Read more.
The separation of chloride and sulphate is important for the treatment of high salt wastewater, and monovalent selective electrodialysis (MSED) has advantages in terms of energy consumption and pre-treatment costs compared to nanofiltration salt separation. Most of the research on monovalent anion-selective membranes (MASM) is still on a laboratory scale due to the preparation process, cost, and other reasons. In this study, a low-cost, easy-to-operate modification scheme was used to prepare MASM, which was applied to assemble a pilot-scale electrodialysis device to treat reverse osmosis concentrated water with a salt content of 4% to 5%. The results indicate that the optimum operating conditions for the device are: 250 L/h influent flow rate for the concentration and dilute compartments, 350 L/h influent flow rate for the electrode compartment and a constant voltage of 20 V. The separation effect of the pilot electrodialysis plant at optimal operating conditions was: the Cl and SO42 transmission rates of 80% and 2.54% respectively, the separation efficiency (S) of 93.85% and the Energy consumption per unit of NaCl (ENaCl) of 0.344 kWh/kg. The analysis of the variation of the three parameters of selective separation performance during electrodialysis indicates that the separation efficiency (S) is a suitable parameter for measuring the selective separation performance of the device compared to the monovalent selectivity coefficient (PSO42Cl). Full article
(This article belongs to the Section Membrane Applications)
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13 pages, 9437 KiB  
Article
Effect of Electrode Type on Electrospun Membrane Morphology Using Low-Concentration PVA Solutions
by Zane Zelca, Andres Krumme, Silvija Kukle, Mihkel Viirsalu and Laimdota Vilcena
Membranes 2022, 12(6), 609; https://doi.org/10.3390/membranes12060609 - 11 Jun 2022
Cited by 4 | Viewed by 1861
Abstract
Electrospun polymer nanofiber materials have been studied as basic materials for various applications. Depending on the intended use of the fibers, their morphology can be adjusted by changing the technological parameters, the properties of the spinning solutions, and the combinations of composition. The [...] Read more.
Electrospun polymer nanofiber materials have been studied as basic materials for various applications. Depending on the intended use of the fibers, their morphology can be adjusted by changing the technological parameters, the properties of the spinning solutions, and the combinations of composition. The aim of the research was to evaluate the effect of electrode type, spinning parameters, polymer molecular weight, and solution concentration on membranes morphology. The main priority was to obtain the smallest possible fiber diameters and homogeneous electrospun membranes. As a result, five electrode types were selected, the lowest PVA solution concentration for stable spinning process was detected, spinning parameters for homogenous fibers were obtained, and the morphology of electrospun fiber membranes was analyzed. Viscosity, conductivity, pH, and density were evaluated for PVA polymers with five different molecular weights (30–145 kDa) and three concentration solutions (6, 8, and 10 wt.%). The membrane defects and fiber diameters were compared as a function of molecular weight and electrode type. The minimum concentration of PVA in the solution allowed more additives to be added to the solution, resulting in thinner diameters and a higher concentration of the additive in the membranes. The molecular weight, concentration, and electrode significantly affected the fiber diameters and the overall quality of the membrane. Full article
(This article belongs to the Section Polymeric Membranes)
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10 pages, 2220 KiB  
Review
Thermo-Statistical Effects of Inclusions on Vesicles: Division into Multispheres and Polyhedral Deformation
by Yuno Natsume
Membranes 2022, 12(6), 608; https://doi.org/10.3390/membranes12060608 - 11 Jun 2022
Viewed by 2091
Abstract
The construction of simple cellular models has attracted much attention as a way to explore the origin of life or elucidate the mechanisms of cell division. In the absence of complex regulatory systems, some bacteria spontaneously divide through thermostatistically elucidated mechanisms, and incorporating [...] Read more.
The construction of simple cellular models has attracted much attention as a way to explore the origin of life or elucidate the mechanisms of cell division. In the absence of complex regulatory systems, some bacteria spontaneously divide through thermostatistically elucidated mechanisms, and incorporating these simple physical principles could help to construct primitive or artificial cells. Because thermodynamic interactions play an essential role in such mechanisms, this review discusses the thermodynamic aspects of spontaneous division models of vesicles that contain a high density of inclusions, with their membrane serving as a boundary. Vesicles with highly dense inclusions are deformed according to the volume-to-area ratio. The phase separation of beads at specific intermediate volume fractions and the associated polyhedral deformation of the membrane are considered in relation to the Alder transition. Current advances in the development of a membrane-growth vesicular model are summarized. The thermostatistical understanding of these mechanisms could become a cornerstone for the construction of vesicular models that display spontaneous cell division. Full article
(This article belongs to the Special Issue Functional Analysis and Applications of Membrane Lipids)
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13 pages, 4380 KiB  
Article
Enhancing Performance of Thin-Film Nanocomposite Membranes by Embedding in Situ Silica Nanoparticles
by Manuel Reyes De Guzman, Micah Belle Marie Yap Ang, Kai-Ting Hsu, Min-Yi Chu, Jeremiah C. Millare, Shu-Hsien Huang, Hui-An Tsai and Kueir-Rarn Lee
Membranes 2022, 12(6), 607; https://doi.org/10.3390/membranes12060607 - 11 Jun 2022
Cited by 2 | Viewed by 1710
Abstract
In this work, silica nanoparticles were produced in situ, to be embedded eventually in the polyamide layer formed during interfacial polymerization for fabricating thin-film nanocomposite membranes with enhanced performance for dehydrating isopropanol solution. The nanoparticles were synthesized through a sol-gel reaction between 3-aminopropyltrimethoxysilane [...] Read more.
In this work, silica nanoparticles were produced in situ, to be embedded eventually in the polyamide layer formed during interfacial polymerization for fabricating thin-film nanocomposite membranes with enhanced performance for dehydrating isopropanol solution. The nanoparticles were synthesized through a sol-gel reaction between 3-aminopropyltrimethoxysilane (APTMOS) and 1,3-cyclohexanediamine (CHDA). Two monomers—CHDA (with APTMOS) and trimesoyl chloride—were reacted on a hydrolyzed polyacrylonitrile (hPAN) support. To obtain optimum fabricating conditions, the ratio of APTMOS to CHDA and reaction time were varied. Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) were used to illustrate the change in morphology as a result of embedding silica nanoparticles. The optimal conditions for preparing the nanocomposite membrane turned out to be 0.15 (g/g) APTMOS/CHDA and 60 min mixing of APTMOS and CHDA, leading to the following membrane performance: flux = 1071 ± 79 g∙m−2∙h−1, water concentration in permeate = 97.34 ± 0.61%, and separation factor = 85.39. A stable performance was shown by the membrane under different operating conditions, where the water concentration in permeate was more than 90 wt%. Therefore, the embedment of silica nanoparticles generated in situ enhanced the separation efficiency of the membrane. Full article
(This article belongs to the Special Issue Advances in Porous and Dense Membranes: Fabrication and Applications)
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