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Membranes, Volume 12, Issue 11 (November 2022) – 144 articles

Cover Story (view full-size image): A team of researchers working in the laboratory of Prof. Ben Hsiao in the Department of Chemistry at Stony Brook University has revealed the effects of incorporating ionic liquid molecules in interfacial polymerization on the structure and property (i.e., permeate flux and salt rejection ratio) relationships of resulting RO membranes. The structure of free-standing polyamide thin films was characterized using grazing incidence wide-angle X-rays scattering (GIWAXS). GIWAXS results corroborated the experimental findings that the membrane prepared using the longer chain IL molecule showed a lower salt rejection ratio and higher permeation flux because of the inclusion of ionic liquid molecules in the polyamide scaffold. View this paper
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18 pages, 2813 KiB  
Article
Landfill Leachate Treatment by Using Second-Hand Reverse Osmosis Membranes: Long-Term Case Study in a Full-Scale Operating Facility
Membranes 2022, 12(11), 1170; https://doi.org/10.3390/membranes12111170 - 21 Nov 2022
Cited by 2 | Viewed by 2070
Abstract
Landfill leachate (LFL) has a complex inorganic, organic and microbiological composition. Although pressure-driven membrane technology contributes to reaching the discharge limits, the need for frequent membrane replacement (typically every 1–3 years) is an economical and environmental limitation. The goal of this work is [...] Read more.
Landfill leachate (LFL) has a complex inorganic, organic and microbiological composition. Although pressure-driven membrane technology contributes to reaching the discharge limits, the need for frequent membrane replacement (typically every 1–3 years) is an economical and environmental limitation. The goal of this work is to evaluate the feasibility of using second-hand reverse osmosis (RO) membranes to treat LFL in an industrially relevant environment. End-of-life RO membranes discarded from a seawater desalination plant were first tested with brackish water and directly reused or regenerated to fit with requirements for LFL treatment. A laboratory scale test of second-hand membrane reuse was carried out using ultrafiltered LFL. Then, a long-term test in an LFL full-scale facility was performed, where half of the membranes of the facility were replaced. The industrial plant was operated for 27 months with second-hand membranes. The permeate water quality fit the required standards and the process showed a trend of lower energy requirement (up to 12 bar lower transmembrane pressure and up to 9% higher recovery than the average of the previous 4 years). Direct reuse and membrane regeneration were successfully proven to be an alternative management to landfill disposal, boosting membranes towards the circular economy. Full article
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22 pages, 3118 KiB  
Article
Buccal Thin Films as Potent Permeation Enhancers for Cytisine Transbuccal Delivery
Membranes 2022, 12(11), 1169; https://doi.org/10.3390/membranes12111169 - 21 Nov 2022
Cited by 1 | Viewed by 1472
Abstract
Cytisine (CYT) is a powerful anti-smoking compound which could greatly benefit from transbuccal delivery because of both its unfavorable pharmacokinetics after oral administration and its intrinsic ability to permeate the buccal mucosa. This work aims to design CYT-loaded buccal thin films suitable for [...] Read more.
Cytisine (CYT) is a powerful anti-smoking compound which could greatly benefit from transbuccal delivery because of both its unfavorable pharmacokinetics after oral administration and its intrinsic ability to permeate the buccal mucosa. This work aims to design CYT-loaded buccal thin films suitable for transbuccal drug delivery due to its capability of promoting the interaction between CYT and the buccal membrane. The solvent casting method was employed to prepare several thin films combining various excipients such as matrixing polymers, mucoadhesion agents, plasticizers and other compounds as humectants and sweeteners, component ratios and solvents. A total of 36 compositions was prepared and four of them emerged as the most promising in terms of aspect and flexibility. They all demonstrated homogeneity, thinness, low swelling degree, and controlled drug release according to the Power Law and Peppas-Sahlin mathematical models. Mainly, they proved able to interact with the ex vivo porcine buccal mucosa producing mucoadhesive effects, and act as potent permeation enhancers. In particular, Film B emerged as suitable as it produced a 10.6-fold Kp enhancement and a great Js value (52.33 μg/cm2·h−1), even when compared to highly concentrated CYT solutions. Full article
(This article belongs to the Special Issue Modern Studies on Drug-Membrane Interactions)
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14 pages, 5687 KiB  
Article
The Influence of Mechanical Stress Micro Fields around Pores on the Strength of Elongated Etched Membrane
Membranes 2022, 12(11), 1168; https://doi.org/10.3390/membranes12111168 - 21 Nov 2022
Cited by 2 | Viewed by 1118
Abstract
The investigation of the mechanical properties of polymer track-etched membranes (TMs) has attracted significant attention in connection with the extended region of their possible applications. In the present work, the mechanical stress fields around the pores of an elongated polyethylene terephthalate TM and [...] Read more.
The investigation of the mechanical properties of polymer track-etched membranes (TMs) has attracted significant attention in connection with the extended region of their possible applications. In the present work, the mechanical stress fields around the pores of an elongated polyethylene terephthalate TM and around the 0.3 mm holes in model polymer specimens were studied in polarized light and with the finite element method. A break-up experiment showed the controlling role of stress field interaction in the forming of a microcrack system and the generation of a main crack with rupture of the TM (or model pattern). This interaction depended on the relative distance between the pores (holes) and their orientation. The results of the calculations of the pore distribution function over the surface of the TM via the net method and wavelet analysis are presented. The fractal character of pore distribution was established. The geometric characteristics of the TM pore system as initial defects are inherited by obtaining TM-based composites. Full article
(This article belongs to the Special Issue Modeling and Simulation of Polymeric Membrane)
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14 pages, 1931 KiB  
Article
Current Distribution in the Discharge Unit of a 10-Cell Vanadium Redox Flow Battery: Comparison of the Computational Model with Experiment
Membranes 2022, 12(11), 1167; https://doi.org/10.3390/membranes12111167 - 21 Nov 2022
Viewed by 1541
Abstract
Shunting currents are among the main problems of all-vanadium redox flow battery stacks since, in addition to capacity losses, they cause negative effects associated with the local destruction of electrodes and bipolar plates. The values of both the shunting currents and their destructive [...] Read more.
Shunting currents are among the main problems of all-vanadium redox flow battery stacks since, in addition to capacity losses, they cause negative effects associated with the local destruction of electrodes and bipolar plates. The values of both the shunting currents and their destructive effects on materials can be reduced at the battery development stage by adjusting the resistance of the electrolyte supply channels. The solution to this problem can be found using a calculation model for current distribution based on the current balance in the nodes as well as voltage drops and electromotive force in internal circuits according to Kirchhoff’s laws. This paper presents the verification of the model of current distribution in an all-vanadium redox flow battery stack of an original design that allows for the determination of membrane-electrode assembly resistances and electrolyte supply channels via direct measurements. Based on a comparison of the calculated and experimental values of the coulombic efficiency of charge–discharge cycles, the capacity fade associated with the crossover of vanadium compounds through the membrane has been determined. Full article
(This article belongs to the Section Membrane Applications)
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14 pages, 904 KiB  
Article
Discovery of the Potentiator of the Pore-Forming Ability of Lantibiotic Nisin: Perspectives for Anticancer Therapy
Membranes 2022, 12(11), 1166; https://doi.org/10.3390/membranes12111166 - 20 Nov 2022
Cited by 6 | Viewed by 1184
Abstract
This study was focused on the action of lantibiotic nisin on the phospholipid membranes. Nisin did not produce ion-permeable pores in the membranes composed of DOPC or DOPE. The introduction of DOPS into bilayer lipid composition led to a decrease in the threshold [...] Read more.
This study was focused on the action of lantibiotic nisin on the phospholipid membranes. Nisin did not produce ion-permeable pores in the membranes composed of DOPC or DOPE. The introduction of DOPS into bilayer lipid composition led to a decrease in the threshold detergent concentration of nisin. An addition of nisin to DOPG- and TOCL-enriched bilayers caused the formation of well-defined ion pores of various conductances. The transmembrane macroscopic current increased with the second power of the lantibiotic aqueous concentration, suggesting that the dimer of nisin was at least involved in the formation of conductive subunit. The pore-forming ability of lantibiotic decreased in the series: DOPC/TOCL ≈ DOPE/TOCL >> DOPC/DOPG ≥ DOPE/DOPG. The preferential interaction of nisin to cardiolipin-enriched bilayers might explain its antitumor activity by pore-formation in mitochondrial membranes. Small natural molecules, phloretin and capsaicin, were found to potentiate the membrane activity of nisin in the TOCL-containing membranes. The effect was referred to as changes in the membrane boundary potential at the adsorption of small molecules. We concluded that the compounds diminishing the membrane boundary potential should be considered as the potentiator of the nisin pore-forming ability that can be used to develop innovative formulations for anticancer therapy. Full article
(This article belongs to the Special Issue Ion Channels in Membranes)
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16 pages, 2008 KiB  
Article
Influence of Membrane Fouling and Reverse Salt Flux on Membrane Impedance of Forward Osmosis Microbial Fuel Cell
Membranes 2022, 12(11), 1165; https://doi.org/10.3390/membranes12111165 - 19 Nov 2022
Cited by 8 | Viewed by 1392
Abstract
The forward osmosis membrane (FO membrane) is an emerging wastewater treatment technology in bioelectricity generation, organic substrate removal and wastewater reclamation. Compared with traditional membrane materials, the FO membrane has a more uniform water content distribution and internal solution concentration distribution. In the [...] Read more.
The forward osmosis membrane (FO membrane) is an emerging wastewater treatment technology in bioelectricity generation, organic substrate removal and wastewater reclamation. Compared with traditional membrane materials, the FO membrane has a more uniform water content distribution and internal solution concentration distribution. In the past, it was believed that one of the important factors restricting power generation was membrane fouling. This study innovatively constructed a mass transfer model of a fouling membrane. Through the analysis of the hydraulic resistance coefficient and the salt mass transfer resistance coefficient, the driving force and the tendency of reverse salt flux during membrane fouling were determined by the model. A surprising discovery was that the fouling membrane can also achieve efficient power generation. The results showed that the hydraulic resistance coefficient of the fouling membrane increased to 4.97 times the initial value, while the salt mass transfer resistance coefficient did not change significantly. Meanwhile, membrane fouling caused concentration polarization in the FO membrane, which enhanced the reverse trend of salt, and the enhancement effect was significantly higher than the impact of the water flux decline caused by membrane pollution. This will make an important contribution to research on FO membrane technology as sustainable membrane technology in wastewater treatment. Full article
(This article belongs to the Section Membrane Applications)
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16 pages, 4086 KiB  
Article
Enhancing the Ammonia Selectivity by Using Nanofiber PVDF Composite Membranes Fabricated with Functionalized Carbon Nanotubes
Membranes 2022, 12(11), 1164; https://doi.org/10.3390/membranes12111164 - 19 Nov 2022
Cited by 3 | Viewed by 1483
Abstract
Conventional hydrophobic membrane-based membrane distillation (MD) has been applied for ammonia recovery from an anaerobic digestion (AD) effluent. However, the typical hydrophobic membranes do not have selectivity for ammonia and water vapor, which results in high energy consumption from the water evaporation. To [...] Read more.
Conventional hydrophobic membrane-based membrane distillation (MD) has been applied for ammonia recovery from an anaerobic digestion (AD) effluent. However, the typical hydrophobic membranes do not have selectivity for ammonia and water vapor, which results in high energy consumption from the water evaporation. To enhance the selectivity during the ammonia recovery process, the functionalized carbon nanotubes (CNTs)/polyvinylidene fluoride (PVDF) nanofiber membranes were fabricated by electrospinning, and the effects of different CNTs and their contents on the performance of nanofiber membranes were investigated. The results indicate that CNTs can be successfully incorporated into nanofibers by electrospinning. The contact angles of the composite membrane are all higher than those of commercial membrane, and the highest value 138° can be obtained. Most importantly, under the condition of no pH adjustment, the ammonia nitrogen transfer coefficient reaches the maximum value of 3.41 × 10−6 m/s, which is about twice higher than that of commercial membranes. The ammonia separation factor of the carboxylated CNT (C-CNT) composite membrane is higher than that of the hydroxylated CNT(H-CNT) composite membrane. Compared with the application of the novel C-CNT composite membrane, the ammonia separation factor is 47% and 25% higher than that of commercial and neat PVDF membranes. This work gives a novel approach for enhancing ammonia and water selectivity during AD effluent treatment. Full article
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13 pages, 2716 KiB  
Article
Studying Different Operating Conditions on Reverse Osmosis Performance in the Treatment of Wastewater Containing Nickel (II) Ions
Membranes 2022, 12(11), 1163; https://doi.org/10.3390/membranes12111163 - 18 Nov 2022
Cited by 2 | Viewed by 1557
Abstract
The reverse osmosis performance in removing nickel ions from artificial wastewater was experimentally and mathematically assessed. The impact of temperature, pressure, feed concentration, and feed flow rate on the permeate flux and Ni (II) rejection % were studied. Experiments were conducted using a [...] Read more.
The reverse osmosis performance in removing nickel ions from artificial wastewater was experimentally and mathematically assessed. The impact of temperature, pressure, feed concentration, and feed flow rate on the permeate flux and Ni (II) rejection % were studied. Experiments were conducted using a SEPA CF042 Membrane Test Skid—TFC BW30XFR with applied pressures of 10, 20, 30, and 40 bar and feed concentrations of 25, 50, 100, and 150 ppm with varying operating temperatures of 25, 35, and 45 °C, while the feed flow rate was changed between 2, 3.2, and 4.4 L/min. The permeate flux and the Ni (II) removal % were directly proportional to the feed temperature and operating pressure, but inversely proportional to the feed concentration, where the permeate flux increased by 49% when the temperature was raised from 25 to 45 °C, while the Ni (II) removal % slightly increased by 4%. In addition, the permeate flux increased by 188% and the Ni (II) removal % increased to 95.19% when the pressure was raised from 10 to 40 bar. The feed flow rate, on the other hand, had a negligible influence on the permeate flux and Ni (II) removal %. The temperature correction factor (TCF) was determined to be directly proportional to the feed temperature, but inversely proportional to the operating pressure; nevertheless, the TCF was unaffected either by the feed flow rate or the feed concentration. Based on the experimental data, mathematical models were generated for both the permeate flux and nickel removal %. The results showed that both models matched the experimental data well. Full article
(This article belongs to the Special Issue Membrane Technologies for Sustainability)
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11 pages, 1986 KiB  
Article
The Interaction between hERG1 and β1 Integrins Modulates hERG1 Current in Different Pathological Cell Models
Membranes 2022, 12(11), 1162; https://doi.org/10.3390/membranes12111162 - 18 Nov 2022
Cited by 1 | Viewed by 1262
Abstract
Ion channels are implicated in various diseases, including cancer, in which they modulate different aspects of cancer progression. In particular, potassium channels are often aberrantly expressed in cancers, a major example being provided by hERG1. The latter is generally complexed with β1 integrin [...] Read more.
Ion channels are implicated in various diseases, including cancer, in which they modulate different aspects of cancer progression. In particular, potassium channels are often aberrantly expressed in cancers, a major example being provided by hERG1. The latter is generally complexed with β1 integrin in tumour cells, and such a molecular complex represents a new druggable hub. The present study focuses on the characterization of the functional consequences of the interaction between hERG1 and β1 integrins on different substrates over time. To this purpose, we studied the interplay alteration on the plasma membrane through patch clamp techniques in a cellular model consisting of human embryonic kidney (HEK) cells stably transfected with hERG1 and in a cancer cell model consisting of SH-SY5Y neuroblastoma cells, endogenously expressing the channel. Cells were seeded on different substrates known to stimulate β1 integrins, such as fibronectin (FN) for HEK-hERG1 and laminin (LMN) for SH-SY5Y. In HEK cells stably overexpressing hERG1, we observed a hERG1 current density increase accompanied by Vrest hyperpolarization after cell seeding onto FN. Notably, a similar behaviour was shown by SH-SY5Y neuroblastoma cells plated onto LMN. Interestingly, we did not observe this phenomenon when plating the cells on substrates such as Bovine Serum Albumin (BSA) or Polylysine (PL), thus suggesting a crucial involvement of ECM proteins as well as of β1 integrin activation. Full article
(This article belongs to the Special Issue Ion Channels in Membranes)
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21 pages, 3474 KiB  
Review
Transmembrane Membrane Readers form a Novel Class of Proteins That Include Peripheral Phosphoinositide Recognition Domains and Viral Spikes
Membranes 2022, 12(11), 1161; https://doi.org/10.3390/membranes12111161 - 17 Nov 2022
Cited by 3 | Viewed by 2210
Abstract
Membrane proteins are broadly classified as transmembrane (TM) or peripheral, with functions that pertain to only a single bilayer at a given time. Here, we explicate a class of proteins that contain both transmembrane and peripheral domains, which we dub transmembrane membrane readers [...] Read more.
Membrane proteins are broadly classified as transmembrane (TM) or peripheral, with functions that pertain to only a single bilayer at a given time. Here, we explicate a class of proteins that contain both transmembrane and peripheral domains, which we dub transmembrane membrane readers (TMMRs). Their transmembrane and peripheral elements anchor them to one bilayer and reversibly attach them to another section of bilayer, respectively, positioning them to tether and fuse membranes while recognizing signals such as phosphoinositides (PIs) and modifying lipid chemistries in proximity to their transmembrane domains. Here, we analyze full-length models from AlphaFold2 and Rosetta, as well as structures from nuclear magnetic resonance (NMR) spectroscopy and X-ray crystallography, using the Membrane Optimal Docking Area (MODA) program to map their membrane-binding surfaces. Eukaryotic TMMRs include phospholipid-binding C1, C2, CRAL-TRIO, FYVE, GRAM, GTPase, MATH, PDZ, PH, PX, SMP, StART and WD domains within proteins including protrudin, sorting nexins and synaptotagmins. The spike proteins of SARS-CoV-2 as well as other viruses are also TMMRs, seeing as they are anchored into the viral membrane while mediating fusion with host cell membranes. As such, TMMRs have key roles in cell biology and membrane trafficking, and include drug targets for diseases such as COVID-19. Full article
(This article belongs to the Section Biological Membrane Composition and Structures)
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18 pages, 12808 KiB  
Article
Membranes Based on PTMSP/PVTMS Blends for Membrane Contactor Applications
Membranes 2022, 12(11), 1160; https://doi.org/10.3390/membranes12111160 - 17 Nov 2022
Cited by 4 | Viewed by 1269
Abstract
In this work, perspective polymeric materials were developed for membrane contactor applications, e.g., for the dissolved oxygen removal from amine CO2 capture solvents. Several polymeric blends based on poly[1-trimethylsilyl-1-propyne] (PTMSP) and poly[vinyltrimethylsilane] (PVTMS) were studied. The gas and water vapor sorption and [...] Read more.
In this work, perspective polymeric materials were developed for membrane contactor applications, e.g., for the dissolved oxygen removal from amine CO2 capture solvents. Several polymeric blends based on poly[1-trimethylsilyl-1-propyne] (PTMSP) and poly[vinyltrimethylsilane] (PVTMS) were studied. The gas and water vapor sorption and permeability coefficients for the PTMSP/PVTMS blend membranes at different PVTMS contents (0–100%) were obtained under temperatures of 30 and 60 °C for the first time. As the PVTMS content increases, the O2 and CO2 permeabilities decrease by 160 and 195 times at 30 °C, respectively. The fractional accessible volume of the polymer blends decreases accordingly. The transport of the CO2 capture solvent vapors through the PTMSP/PVTMS blend membranes were determined in thermo-pervaporation (TPV) mode using aqueous monoethanolamine (30%), N-methyldiethanolamine (40%), and 2-amino-2-methyl-1-propanol (30%) solutions as model amine solvents at 60 °C. The membranes demonstrated high pervaporation separation factors with respect to water, resulting in low amine losses. A joint analysis of the gas permeabilities and aqueous alkanolamine TPV data allowed us to conclude that the polymer blend composition of PTMSP/PVTMS 70/30 provides an optimal combination of a sufficiently high oxygen permeability and the pervaporation separation factor at a temperature of 60 °C. Full article
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13 pages, 4467 KiB  
Article
Improved Hydrolytic and Mechanical Stability of Sulfonated Aromatic Proton Exchange Membranes Reinforced by Electrospun PPSU Fibers
Membranes 2022, 12(11), 1159; https://doi.org/10.3390/membranes12111159 - 17 Nov 2022
Viewed by 1328
Abstract
The hydrolytic stability of ionomer membranes is a matter of concern for the long-term durability of energy storage and conversion devices. Various reinforcement strategies exist for the improvement of the performances of the overall membrane. We propose in this article the stabilization of [...] Read more.
The hydrolytic stability of ionomer membranes is a matter of concern for the long-term durability of energy storage and conversion devices. Various reinforcement strategies exist for the improvement of the performances of the overall membrane. We propose in this article the stabilization of membranes based on aromatic ion conducting polymers (SPEEK and SPPSU) by the introduction of an electrospun mat of inexpensive PPSU polymer. Characterization data from hydrolytic stability (mass uptake and dimension change) and from mechanical and conductivity measurements show an improved stability of membranes in phosphate buffer, used for enzymatic fuel cells, and in distilled water. The synergistic effect of the reinforcement, together with the casting solvent and the thermal treatment or blending polymers, is promising for the realization of high stability ionomer membranes. Full article
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17 pages, 7077 KiB  
Article
Electrospun Nanofiber/Textile Supported Composite Membranes with Improved Mechanical Performance for Biomedical Applications
Membranes 2022, 12(11), 1158; https://doi.org/10.3390/membranes12111158 - 17 Nov 2022
Cited by 8 | Viewed by 1776
Abstract
Textile-supported nanocomposite as a scaffold has been extensively used in the medical field, mainly to give support to weak or harmed tissues. However, there are some challenges in fabricating the nanofiber/textile composite, i.e., suitable porous structure with defined pore size, less skin contact [...] Read more.
Textile-supported nanocomposite as a scaffold has been extensively used in the medical field, mainly to give support to weak or harmed tissues. However, there are some challenges in fabricating the nanofiber/textile composite, i.e., suitable porous structure with defined pore size, less skin contact area, biocompatibility, and availability of degradable materials. Herein, polyamide-6 (PA) nanofibers were synthesized using needleless electrospinning with the toothed wheel as a spinneret. The electrospinning process was optimized using different process and solution parameters. In the next phase, optimized PA nanofiber membranes of optimum fiber diameter with uniform distribution and thickness were used in making nanofiber membrane–textile composite. Different textile fabrics (woven, non-woven, knitted) were developed. The optimized nanofiber membranes were combined with non-woven, woven, and knitted fabrics to make fabric-supported nanocomposite. The nanofiber/fabric composites were compared with available market woven and knitted meshes for mechanical properties, morphology, structure, and chemical interaction analysis. It was found that the tear strength of the nanofiber/woven composite was three times higher than market woven mesh, and the nanofiber/knitted composite was 2.5 times higher than market knitted mesh. The developed composite structures with woven and knitted fabric exhibited improved bursting strength (613.1 and 751.1 Kpa), tensile strength (195.76 and 227.85 N), and puncture resistance (68.76 and 57.47 N), respectively, than market available meshes. All these properties showed that PA nanofibers/textile structures could be utilized as a composite with multifunctional properties. Full article
(This article belongs to the Special Issue Recent Advances in Electrospun Nanofiber Membranes)
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9 pages, 2035 KiB  
Article
Microstructure and Hydrogen Permeability of Nb-Ni-Ti-Zr-Co High Entropy Alloys
Membranes 2022, 12(11), 1157; https://doi.org/10.3390/membranes12111157 - 17 Nov 2022
Cited by 4 | Viewed by 1800
Abstract
Hydrogen separation membranes are one of the most promising technologies for hydrogen purification. The development of high-entropy alloys (HEAs) for hydrogen separation membranes is driven by a “cocktail effect” of elements with different hydrogen affinities to prevent hydride formation and retain high permeability [...] Read more.
Hydrogen separation membranes are one of the most promising technologies for hydrogen purification. The development of high-entropy alloys (HEAs) for hydrogen separation membranes is driven by a “cocktail effect” of elements with different hydrogen affinities to prevent hydride formation and retain high permeability due to the single-phase BCC structure. In this paper, equimolar and non-equimolar Nb-Ni-Ti-Zr-Co high entropy alloys were fabricated by arc melting. The microstructure and phase composition of the alloys were analyzed by scanning electron microscopy and X-ray diffraction, respectively. The hydrogen permeation experiments were performed at 300–500 °C and a hydrogen pressure of 4 bar. In order to estimate the effect of composition and lattice structure on hydrogen location and diffusivity in Nb-Ni-Ti-Zr-Co alloy, ab initio calculations of hydrogen binding energy were performed using virtual crystal approximation. It was found that Nb-enriched and near equimolar BCC phases were formed in Nb20Ni20Ti20Zr20Co20 HEA while Nb-enriched BCC and B2-Ni(Ti, Zr) were formed in Nb40Ni25Ti18Zr12Co5 alloy. Hydrogen permeability tests showed that Nb20Ni20Ti20Zr20Co20 HEA shows lower activation energy and higher permeability at lower temperatures as well as higher resistance to hydrogen embrittlement compared to Nb40Ni25Ti18Zr12Co5 alloy. The effect of composition, microstructure and hydrogen binding energies on permeability of the fabricated alloys was discussed. Full article
(This article belongs to the Special Issue Recent Advances in Membrane Filtration and Purification Technologies)
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9 pages, 1433 KiB  
Article
A Novel Membrane-like 2D A’-MoS2 as Anode for Lithium- and Sodium-Ion Batteries
Membranes 2022, 12(11), 1156; https://doi.org/10.3390/membranes12111156 - 16 Nov 2022
Cited by 4 | Viewed by 1712
Abstract
Currently, new nanomaterials for high-capacity lithium-ion batteries (LIBs) and sodium- ion batteries (SIBs) are urgently needed. Materials combining porous structure (such as representatives of metal–organic frameworks) and the ability to operate both with lithium and sodium (such as transition-metal dichalcogenides) are of particular [...] Read more.
Currently, new nanomaterials for high-capacity lithium-ion batteries (LIBs) and sodium- ion batteries (SIBs) are urgently needed. Materials combining porous structure (such as representatives of metal–organic frameworks) and the ability to operate both with lithium and sodium (such as transition-metal dichalcogenides) are of particular interest. Our work reports the computational modelling of a new A’-MoS2 structure and its application in LIBs and SIBs. The A’-MoS2 monolayer was dynamically stable and exhibited semiconducting properties with an indirect band gap of 0.74 eV. A large surface area, together with the presence of pores resulted in a high capacity of the A’-MoS2 equal to ~391 mAg−1 at maximum filling for both Li and Na atoms. High adsorption energies and small values of diffusion barriers indicate that the A’-MoS2 is promising in the application of anode material in LIBs and SIBs. Full article
(This article belongs to the Special Issue Modeling and Simulation of Polymeric Membrane)
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13 pages, 17629 KiB  
Article
Functionalized GO Membranes for Efficient Separation of Acid Gases from Natural Gas: A Computational Mechanistic Understanding
Membranes 2022, 12(11), 1155; https://doi.org/10.3390/membranes12111155 - 16 Nov 2022
Cited by 2 | Viewed by 1663
Abstract
Membrane separation technology is applied in natural gas processing, while a high-performance membrane is highly in demand. This paper considers the bright future of functionalized graphene oxide (GO) membranes in acid gas removal from natural gas. By molecular simulations, the adsorption and diffusion [...] Read more.
Membrane separation technology is applied in natural gas processing, while a high-performance membrane is highly in demand. This paper considers the bright future of functionalized graphene oxide (GO) membranes in acid gas removal from natural gas. By molecular simulations, the adsorption and diffusion behaviors of several unary gases (N2, CH4, CO2, H2S, and SO2) are explored in the 1,4-phenylenediamine-2-sulfonate (PDASA)-doped GO channels. Molecular insights show that the multilayer adsorption of acid gases evaluates well by the Redlich-Peterson model. A tiny amount of PDASA promotes the solubility coefficient of CO2 and H2S, respectively, up to 4.5 and 5.3 mmol·g−1·kPa−1, nearly 2.5 times higher than those of a pure GO membrane, which is due to the improved binding affinity, great isosteric heat, and hydrogen bonds, while N2 and CH4 only show single-layer adsorption with solubility coefficients lower than 0.002 mmol·g−1·kPa−1, and their weak adsorption is insusceptible to PDASA. Although acid gas diffusivity in GO channels is inhibited below 20 × 10−6 cm2·s−1 by PDASA, the solubility coefficient of acid gases is certainly high enough to ensure their separation efficiency. As a result, the permeabilities (P) of acid gases and their selectivities (α) over CH4 are simultaneously improved (PCO2 = 7265.5 Barrer, αCO2/CH4 = 95.7; P(H2S+CO2) = 42075.1 Barrer, αH2S/CH4 = 243.8), which outperforms most of the ever-reported membranes. This theoretical study gives a mechanistic understanding of acid gas separation and provides a unique design strategy to develop high-performance GO membranes toward efficient natural gas processing. Full article
(This article belongs to the Special Issue Preparation and Application of Advanced Functional Membranes)
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20 pages, 4570 KiB  
Article
Electrochemical and Electroconductive Behavior of Silk Fibroin Electrospun Membrane Coated with Gold or Silver Nanoparticles
Membranes 2022, 12(11), 1154; https://doi.org/10.3390/membranes12111154 - 16 Nov 2022
Cited by 1 | Viewed by 1433
Abstract
The surface modification of materials obtained from natural polymers, such as silk fibroin with metal nanoparticles that exhibit intrinsic electrical characteristics, allows the obtaining of biocomposite materials capable of favoring the propagation and conduction of electrical impulses, acting as communicating structures in electrically [...] Read more.
The surface modification of materials obtained from natural polymers, such as silk fibroin with metal nanoparticles that exhibit intrinsic electrical characteristics, allows the obtaining of biocomposite materials capable of favoring the propagation and conduction of electrical impulses, acting as communicating structures in electrically isolated areas. On that basis, this investigation determined the electrochemical and electroconductive behavior through electrochemical impedance spectroscopy of a silk fibroin electrospun membrane from silk fibrous waste functionalized with gold or silver nanoparticles synthetized by green chemical reduction methodologies. Based on the results obtained, we found that silk fibroin from silk fibrous waste (SFw) favored the formation of gold (AuNPs-SFw) and silver (AgNPs-SFw) nanoparticles, acting as a reducing agent and surfactant, forming a micellar structure around the individual nanoparticle. Moreover, different electrospinning conditions influenced the morphological properties of the fibers, in the presence or absence of beads and the amount of sample collected. Furthermore, treated SFw electrospun membranes, functionalized with AuNPs-SFw or AgNPS-SFw, allowed the conduction of electrical stimuli, acting as stimulators and modulators of electric current. Full article
(This article belongs to the Special Issue Nanofibrous Membrane for Biomedical Application)
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11 pages, 1559 KiB  
Article
The Combined Effects of the Membrane and Flow Channel Development on the Performance and Energy Footprint of Oil/Water Emulsion Filtration
Membranes 2022, 12(11), 1153; https://doi.org/10.3390/membranes12111153 - 16 Nov 2022
Cited by 1 | Viewed by 1184
Abstract
Membrane filtration is a promising technology for oil/water emulsion filtration due to its excellent removal efficiency of microdroplets of oil in water. However, its performance is highly limited due to the fouling-prone nature of oil droplets on hydrophobic membranes. Membrane filtration typically suffers [...] Read more.
Membrane filtration is a promising technology for oil/water emulsion filtration due to its excellent removal efficiency of microdroplets of oil in water. However, its performance is highly limited due to the fouling-prone nature of oil droplets on hydrophobic membranes. Membrane filtration typically suffers from a low flux and high pumping energy. This study reports a combined approach to tackling the membrane fouling challenge in oil/water emulsion filtration via a membrane and a flow channel development. Two polysulfone (PSF)-based lab-made membranes, namely PSF- PSF-Nonsolvent induced phase separation (NIPS) and PSF-Vapor-induced phase separation (VIPS), were selected, and the flow channel was modified into a wavy path. They were assessed for the filtration of a synthetic oil/water emulsion. The results showed that the combined membrane and flow channel developments enhanced the clean water permeability with a combined increment of 105%, of which 34% was attributed to the increased effective filtration area due to the wavy flow channel. When evaluated for the filtration of an oil/water emulsion, a 355% permeability increment was achieved from 43 for the PSF-NIPS in the straight flow channel to 198 L m−2 h−1 bar−1 for the PSF-VIPS in the wavy flow channel. This remarkable performance increment was achieved thanks to the antifouling attribute of the developed membrane and enhanced local mixing by the wavy flow channel to limit the membrane fouling. The increase in the filtration performance was translated into up to 78.4% (0.00133 vs. 0.00615 kWh m−3) lower in pumping energy. The overall findings demonstrate a significant improvement by adopting multi-pronged approaches in tackling the challenge of membrane fouling for oil/water emulsion filtration, suggesting the potential of this approach to be applied for other feeds. Full article
(This article belongs to the Special Issue Membrane Science towards Sustainable Development Goals (SDGs))
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15 pages, 3267 KiB  
Article
A New Sensing Material Based on Tetraaza/SBA15 for Rapid Detection of Copper(II) Ion in Water
Membranes 2022, 12(11), 1152; https://doi.org/10.3390/membranes12111152 - 16 Nov 2022
Cited by 1 | Viewed by 1340
Abstract
A novel rapid and sensitive optical sensor for Cu2+ ion detection based on 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-7,14-dienium dibromide (TL) immobilized on Santa Barbara Amorphous (SBA-15) has been successfully developed. The inner and outer space of SBA15 allowed a high capacity of TL compound to immobilize [...] Read more.
A novel rapid and sensitive optical sensor for Cu2+ ion detection based on 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-7,14-dienium dibromide (TL) immobilized on Santa Barbara Amorphous (SBA-15) has been successfully developed. The inner and outer space of SBA15 allowed a high capacity of TL compound to immobilize onto it. FESEM (Field Emission Scanning Electron Microscopy) analysis was performed to confirm the morphology of TL-SBA15, while FTIR (Fourier Transform Infrared Spectroscopy) was utilized to confirm the interaction of TL–SBA15. A binding study of TL compound towards Cu2+ ion was performed via UV-vis solution study and binding titration. The stoichiometric binding ratio and binding constant value Kb of TL towards Cu2+ ion was 1:1 and 2.33 × 103 M−1, respectively. The optical reflectance sensor based on the TL compound is selective to Cu2+ ion and demonstrated a linear response over a Cu2+ ion concentration range of 1 × 10−7 M to 2 × 10−5 M, with a detection limit (LOD) of 1.02 × 10−7 M (R2 = 0.99) and fast response time of < 1 min. It showed high reproducibility, with a relative standard deviation (RSD) obtained at 0.47%. This optical sensor is reusable up to five consecutive times on Cu2+ ion by using 0.1 M EDTA with a pH of 6 as a regeneration solution, with a reversibility RSD value of 0.79%. The developed optical sensor provides a rapid and sensitive tool for Cu2+ ion detection in teabag samples, and the results align with those obtained by the ICP-MS standard method. Full article
(This article belongs to the Special Issue Sensing Membranes)
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11 pages, 3284 KiB  
Article
Plant Polyphenol Pyrogallol and Polyamine-Based Co-Deposition for High-Efficiency Nanofiltration Membrane Preparation towards Inorganic Salt Removal
Membranes 2022, 12(11), 1151; https://doi.org/10.3390/membranes12111151 - 16 Nov 2022
Viewed by 1324
Abstract
The co-deposition between polyphenols and amines has been demonstrated in order to prepare positively charged nanofiltration (NF) membranes for multivalent cation rejection in recent years; however, the low reactivities of the involved polyphenols usually cause a long co-deposition time and unsatisfactory rejection. Herein, [...] Read more.
The co-deposition between polyphenols and amines has been demonstrated in order to prepare positively charged nanofiltration (NF) membranes for multivalent cation rejection in recent years; however, the low reactivities of the involved polyphenols usually cause a long co-deposition time and unsatisfactory rejection. Herein, a novel plant polyphenol (PG) was co-deposited with tetraethylenepentamine (TEPA) in a much shorter time period to prepare positively charged NF with high multivalent cation rejection membranes. The performance of the co-deposition membranes can be easily controlled by adjusting the mass ratio of PG and TEPA, reaction time, and pH value of the buffer solution. The optimal membrane, prepared under a polyphenol and polyamine mass ratio of 1:1, coating time of 2 h, and pH value of 8.0, shows a decent pure water permeability of 8.43 L m−2 h−1 bar−1 while maintaining a superior 96.24% MgCl2 rejection. More importantly, the universality of this method was corroborated by employing other amines with different molecular weights in the co-deposition. This work provides new insights for the preparation of high-performance positively charged NF membranes. Full article
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17 pages, 2520 KiB  
Article
Chloride Ion-Selective Electrode with Solid-Contact Based on Polyaniline Nanofibers and Multiwalled Carbon Nanotubes Nanocomposite
Membranes 2022, 12(11), 1150; https://doi.org/10.3390/membranes12111150 - 16 Nov 2022
Cited by 6 | Viewed by 2240
Abstract
Use of the nanocomposite of chloride-doped polyaniline nanofibers and multiwalled carbon nanotubes (PANINFs-Cl:MWCNTs) for construction of ion-selective electrodes with solid-contact sensitive to chloride ions has been described. Many types of electrodes were tested, differing in the quantitative and qualitative composition of the layer [...] Read more.
Use of the nanocomposite of chloride-doped polyaniline nanofibers and multiwalled carbon nanotubes (PANINFs-Cl:MWCNTs) for construction of ion-selective electrodes with solid-contact sensitive to chloride ions has been described. Many types of electrodes were tested, differing in the quantitative and qualitative composition of the layer placed between the electrode material and the ion-selective membrane. Initial tests were carried out, including tests of electrical properties of intermediate solid-contact layers. The obtained ion-selective electrodes had a theoretical slope of the electrode characteristic curve (−61.3 mV dec−1), a wide range of linearity (5 × 10−6–1 × 10−1 mol L−1) and good potential stability resistant to changing measurement conditions (redox potential, light, oxygen). The chloride contents in the tap, mineral and river water samples were successfully determined using the electrodes. Full article
(This article belongs to the Special Issue Membrane-Based Electrochemical Sensors)
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33 pages, 1288 KiB  
Review
Determination of Elastic Parameters of Lipid Membranes with Molecular Dynamics: A Review of Approaches and Theoretical Aspects
Membranes 2022, 12(11), 1149; https://doi.org/10.3390/membranes12111149 - 16 Nov 2022
Cited by 8 | Viewed by 1891
Abstract
Lipid membranes are abundant in living organisms, where they constitute a surrounding shell for cells and their organelles. There are many circumstances in which the deformations of lipid membranes are involved in living cells: fusion and fission, membrane-mediated interaction between membrane inclusions, lipid–protein [...] Read more.
Lipid membranes are abundant in living organisms, where they constitute a surrounding shell for cells and their organelles. There are many circumstances in which the deformations of lipid membranes are involved in living cells: fusion and fission, membrane-mediated interaction between membrane inclusions, lipid–protein interaction, formation of pores, etc. In all of these cases, elastic parameters of lipid membranes are important for the description of membrane deformations, as these parameters determine energy barriers and characteristic times of membrane-involved phenomena. Since the development of molecular dynamics (MD), a variety of in silico methods have been proposed for the determination of elastic parameters of simulated lipid membranes. These MD methods allow for the consideration of details unattainable in experimental techniques and represent a distinct scientific field, which is rapidly developing. This work provides a review of these MD approaches with a focus on theoretical aspects. Two main challenges are identified: (i) the ambiguity in the transition from the continuum description of elastic theories to the discrete representation of MD simulations, and (ii) the determination of intrinsic elastic parameters of lipid mixtures, which is complicated due to the composition–curvature coupling effect. Full article
(This article belongs to the Special Issue Membrane Regulation of Protein Function)
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15 pages, 4730 KiB  
Article
Ginger Loaded Polyethylene Oxide Electrospun Nanomembrane: Rheological and Antimicrobial Attributes
Membranes 2022, 12(11), 1148; https://doi.org/10.3390/membranes12111148 - 16 Nov 2022
Cited by 6 | Viewed by 1713
Abstract
Synthetic antibiotics have captured the market in recent years, but the side effects of these products are life-threatening. In recent times, researchers have focused their research on natural-based products such as natural herbal oils, which are eco-friendly, biocompatible, biodegradable, and antibacterial. In this [...] Read more.
Synthetic antibiotics have captured the market in recent years, but the side effects of these products are life-threatening. In recent times, researchers have focused their research on natural-based products such as natural herbal oils, which are eco-friendly, biocompatible, biodegradable, and antibacterial. In this study, polyethylene oxide (PEO) and aqueous ginger extract (GE) were electrospun to produce novel antibacterial nanomembrane sheets as a function of PEO and GE concentrations. A GE average particle size of 91.16 nm was achieved with an extensive filtration process, inferring their incorporation in the PEO nanofibres. The presence of the GE was confirmed by Fourier transform infrared spectroscopy (FTIR) through peaks of phenol and aromatic groups. The viscoelastic properties of PEO/GE solutions were analysed in terms of PEO and GE concentrations. Increasing PEO and GE concentrations increased the solution’s viscosity. The dynamic viscosity of 3% was not changed with increasing shear rate, indicating Newtonian fluid behaviour. The dynamic viscosity of 4 and 5 wt% PEO/GE solutions containing 10% GE increased exponentially compared to 3 wt%. In addition, the shear thinning behaviour was observed over a frequency range of 0.05 to 100 rad/s. Scanning Electron Microscopy (SEM) analysis also specified an increase in the nanofibre’s diameter with increasing PEO concentration, while SEM images displayed smooth morphology with beadless nanofibres at different PEO/GE concentrations. In addition, PEO/GE nanomembranes inhibited the growth of Staphylococcus aureus, as presented by qualitative antibacterial results. The extent of PEO/GE nanomembrane’s antibacterial activity was further investigated by the agar dilution method, which inhibited the 98.79% Staphylococcus aureus population at 30% GE concentration. Full article
(This article belongs to the Special Issue Recent Advances in Electrospun Nanofiber Membranes)
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15 pages, 2125 KiB  
Article
Developing a Hybrid Neuro-Fuzzy Method to Predict Carbon Dioxide (CO2) Permeability in Mixed Matrix Membranes Containing SAPO-34 Zeolite
Membranes 2022, 12(11), 1147; https://doi.org/10.3390/membranes12111147 - 16 Nov 2022
Cited by 5 | Viewed by 1539
Abstract
This study compares the predictive performance of different classes of adaptive neuro-fuzzy inference systems (ANFIS) in predicting the permeability of carbon dioxide (CO2) in mixed matrix membrane (MMM) containing the SAPO-34 zeolite. The hybrid neuro-fuzzy technique uses the MMM chemistry, pressure, [...] Read more.
This study compares the predictive performance of different classes of adaptive neuro-fuzzy inference systems (ANFIS) in predicting the permeability of carbon dioxide (CO2) in mixed matrix membrane (MMM) containing the SAPO-34 zeolite. The hybrid neuro-fuzzy technique uses the MMM chemistry, pressure, and temperature to estimate CO2 permeability. Indeed, grid partitioning (GP), fuzzy C-means (FCM), and subtractive clustering (SC) strategies are used to divide the input space of ANFIS. Statistical analyses compare the performance of these strategies, and the spider graph technique selects the best one. As a result of the prediction of more than 100 experimental samples, the ANFIS with the subtractive clustering method shows better accuracy than the other classes. The hybrid optimization algorithm and cluster radius = 0.55 are the best hyperparameters of this ANFIS model. This neuro-fuzzy model predicts the experimental database with an absolute average relative deviation (AARD) of less than 3% and a correlation of determination higher than 0.995. Such an intelligent model is not only straightforward but also helps to find the best MMM chemistry and operating conditions to maximize CO2 separation. Full article
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15 pages, 2525 KiB  
Article
Antibacterial Capability of MXene (Ti3C2Tx) to Produce PLA Active Contact Surfaces for Food Packaging Applications
Membranes 2022, 12(11), 1146; https://doi.org/10.3390/membranes12111146 - 15 Nov 2022
Cited by 7 | Viewed by 2025
Abstract
The globalization of the market and the increase of the global population that requires a higher demand of food products superimposes a big challenge to ensure food safety. In this sense, a common strategy to extend the shelf life and save life of [...] Read more.
The globalization of the market and the increase of the global population that requires a higher demand of food products superimposes a big challenge to ensure food safety. In this sense, a common strategy to extend the shelf life and save life of food products is by avoiding bacterial contamination. For this, the development of antibacterial contact surfaces is an urgent need to fulfil the above-mentioned strategy. In this work, the role of MXene (Ti3C2Tx) in providing antibacterial contact surfaces was studied through the creation of composite films from polylactic acid (PLA), as the chosen polymeric matrix. The developed PLA/MXene films maintained the thermal and mechanical properties of PLA and also presented the attractive antibacterial properties of MXene. The composites’ behaviour against two representative foodborne bacteria was studied: Listeria mono-cytogenes and Salmonella enterica (representing Gram-positive and Gram-negative bacteria, respectively). The composites prevented bacterial growth, and in the case of Listeria only 0.5 wt.% of MXene was necessary to reach 99.9999% bactericidal activity (six log reductions), while against Salmonella, 5 wt.% was necessary to achieve 99.999% bactericidal activity (five log reductions). Cy-totoxicity tests with fHDF/TER166 cell line showed that none of the obtained materials were cytotoxic. These results make MXene particles promising candidates for their use as additives into a polymeric matrix, useful to fabricate antibacterial contact surfaces that could prove useful for the food packaging industry. Full article
(This article belongs to the Special Issue Biodegradable Films Characterization and Food Packaging)
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15 pages, 2551 KiB  
Article
Optimization of the Design Configuration and Operation Strategy of Single-Pass Seawater Reverse Osmosis
Membranes 2022, 12(11), 1145; https://doi.org/10.3390/membranes12111145 - 15 Nov 2022
Viewed by 1412
Abstract
The numerical study was conducted to compare process performance depending on the pump type and process configuration. The daily monitoring data of seawater temperature and salinity offshore from Daesan, Republic of Korea was used to reflect the site-specific seawater conditions. An algorithm for [...] Read more.
The numerical study was conducted to compare process performance depending on the pump type and process configuration. The daily monitoring data of seawater temperature and salinity offshore from Daesan, Republic of Korea was used to reflect the site-specific seawater conditions. An algorithm for reverse osmosis in constant permeate mode was developed to simulate the process in time-variant conditions. Two types of pumps with different maximum leachable efficiencies were employed to organize pump-train configuration: separated feed lines and common pressure center design. The results showed pump type and design configuration did not have a significant effect on process performance. The annual means of specific energy consumption (SEC) for every design configuration were under 2 kWh/m3, except for a worst-case. The worst-case was decided when the pump was operated out of the best operation range. The two operation strategies were evaluated to determine the optimal configuration. The permeate flow rate was reduced to 80% of the designed permeate flow rate with two approaches: feed flow rate reduction in every train and pump shutdown in a specific train. The operation mode with feed flow rate reduction was more efficient than the other. The operating pressure reduction led to a decrease in SEC. Full article
(This article belongs to the Special Issue Modeling and Prediction of the Performance of Membrane Processes)
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18 pages, 4046 KiB  
Article
Electromass Transfer in the System “Cation Exchange Membrane—Ammonium Nitrate Solution”
Membranes 2022, 12(11), 1144; https://doi.org/10.3390/membranes12111144 - 15 Nov 2022
Cited by 2 | Viewed by 1345
Abstract
The paper describes an experimental study and the mathematical simulation of the electromembrane transfer of cations of weak electrolytes (namely, ammonium ions), hindered by hydrolysis reactions taking place in the surface layers of the cation exchange membrane. Using the finite element method, we [...] Read more.
The paper describes an experimental study and the mathematical simulation of the electromembrane transfer of cations of weak electrolytes (namely, ammonium ions), hindered by hydrolysis reactions taking place in the surface layers of the cation exchange membrane. Using the finite element method, we found a solution to the corresponding diffusion-kinetic electrodialysis problem in potentiostatic mode. Based on the experimental data and the results of theoretical simulation, we analyzed the effect of hydrolysis on the concentration polarization of the electromembrane system and the transport characteristics of ions, and suggested a mechanism of transfer of the components of the ammonium nitrate solution through the cation exchange membrane. Full article
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22 pages, 7722 KiB  
Article
A Comparative Analysis of the Effect of Carbonaceous Nanoparticles on the Physicochemical Properties of Hybrid Polyethersulfone Ultrafiltration Membranes
Membranes 2022, 12(11), 1143; https://doi.org/10.3390/membranes12111143 - 15 Nov 2022
Cited by 6 | Viewed by 1837
Abstract
Numerous studies have been previously reported on the use of nanoscale carbonaceous fillers, such as multi-walled carbon nanotubes (MWCNTs) and graphene oxide (GO), in polymeric ultrafiltration (UF) membranes; however, no insight has been clearly reported on which material provides the best enhancements in [...] Read more.
Numerous studies have been previously reported on the use of nanoscale carbonaceous fillers, such as multi-walled carbon nanotubes (MWCNTs) and graphene oxide (GO), in polymeric ultrafiltration (UF) membranes; however, no insight has been clearly reported on which material provides the best enhancements in membrane performance. In this study, a comparative analysis was carried out to establish a comprehensible understanding of the physicochemical properties of hybrid polyethersulfone (PES) UF membranes incorporated with MWCNTs and GO nanoparticles at various concentrations. The hybrid membranes were prepared via the non-solvent-induced phase separation process and further characterized by field emission scanning electron microscopy and atomic force microscope (AFM). The AFM images showed homogeneous membrane surfaces with a reduction in the membrane surface roughness from 2.62 nm for bare PES to 2.39 nm for PES/MWCNTs and to 1.68 nm for PES/GO membranes due to improved hydrophilicity of the membranes. Physicochemical properties of the hybrid PES membranes were assessed, and the outcomes showed an enhancement in the porosity, pore size, water contact angle, and water permeability with respect to nanoparticle concentration. GO-incorporated PES membranes exhibited the highest porosity, pore size, and lowest contact angle as compared to PES/MWCNTs, indicating the homogeneous distribution of nanoparticles within the membrane structure. PES/MWCNTs (0.5 wt.%) and PES/GO (1.0 wt.%) hybrid membranes exhibited the highest water flux of 450.0 and 554.8 L m−2 h−1, respectively, at an applied operating pressure of 1 bar. The filtration and antifouling performance of the PES hybrid membranes were evaluated using 50 mg L−1 of humic acid (HA) as a foulant at pH = 7. Compared to the bare PES membrane, the MWCNTs and GO-incorporated PES hybrid membranes exhibited enhanced permeability and HA removal. Moreover, PES/MWCNTs (0.5 wt.%) and PES/GO (1 wt.%) hybrid membranes reported HA rejection of 90.8% and 94.8%, respectively. The abundant oxygen-containing functional groups in GO-incorporated PES membranes resulted in more hydrophilic membranes, leading to enhanced permeability and fouling resistance. The antifouling properties and flux recovery ratio were improved by the addition of both nanoparticles. Given these findings, although both MWCNTs and GO nanoparticles are seen to notably improve the membrane performance, PES membranes with 1 wt.% GO loading provided the highest removal of natural organic matter, such as HA, under the same experimental conditions. Full article
(This article belongs to the Special Issue Feature Papers in Membrane Analysis and Characterization)
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12 pages, 3097 KiB  
Article
Electrodialysis for the Concentration of Lithium-Containing Brines—An Investigation on the Applicability
Membranes 2022, 12(11), 1142; https://doi.org/10.3390/membranes12111142 - 15 Nov 2022
Viewed by 2081
Abstract
The importance of lithium as a raw material is steadily increasing, especially in the growing markets of grid energy and e-mobility. Today, brines are the most important lithium sources. The rising lithium demand raises concerns over the expandability and the environmental impact of [...] Read more.
The importance of lithium as a raw material is steadily increasing, especially in the growing markets of grid energy and e-mobility. Today, brines are the most important lithium sources. The rising lithium demand raises concerns over the expandability and the environmental impact of common mining techniques, which are mainly based on the evaporation of brine solutions (Salars) in arid and semiarid areas. In this case, much of the water contained in the brine is lost. Purification processes lead to further water losses of the ecosystems. This calls for new and improved processes for lithium production; one of them is electrodialysis (ED). Electrodialysis offers great potential in accessing lithium from brines in a more environmentally friendly way; furthermore, for the recovery of lithium from spent lithium-ion batteries (LIB), electrodialysis may become a vital technology. The following study focused on investigating the effect of varying brine compositions, different ED operation modes, and limiting factors on the use of ED for concentrating lithium-containing brine solutions. Synthetic lithium salt solutions (LiCl, LiOH) were concentrated using conventional ED in batch-wise operation. While the diluate solution was exchanged once a defined minimum concentration was reached, the concentrate solution was concentrated to the respective maximum. The experiments were conducted using a lab-scale ED-plant (BED1-3 from PCCell GmbH, Germany). The ion-exchange membranes used were PCSK and PCSA. The treated solutions varied in concentration and composition. Parameters such as current density, current efficiency, and energy requirements were evaluated. ED proved highly effective in the concentration of lithium salt solutions. Lithium chloride solutions were concentrated up to approximately 18-fold of the initial concentration. Current efficiencies and current densities depended on voltage, concentration, and the composition of the brine. Overall, the current efficiencies reached maximum values of around 70%. Furthermore, the experiments revealed a water transport of about 0.05 to 0.075% per gram of LiCl transferred from the diluate solution to the concentrate solution. Full article
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17 pages, 2670 KiB  
Article
Power Generation Performance of Reverse Electrodialysis (RED) Using Various Ion Exchange Membranes and Power Output Prediction for a Large RED Stack
Membranes 2022, 12(11), 1141; https://doi.org/10.3390/membranes12111141 - 13 Nov 2022
Cited by 3 | Viewed by 2033
Abstract
Reverse electrodialysis (RED) power generation using seawater (SW) and river water is expected to be a promising environmentally friendly power generation system. Experiments with large RED stacks are needed for the practical application of RED power generation, but only a few experimental results [...] Read more.
Reverse electrodialysis (RED) power generation using seawater (SW) and river water is expected to be a promising environmentally friendly power generation system. Experiments with large RED stacks are needed for the practical application of RED power generation, but only a few experimental results exist because of the need for large facilities and a large area of ion-exchange membranes (IEMs). In this study, to predict the power output of a large RED stack, the power generation performances of a lab-scale RED stack (40 membrane pairs and 7040 cm2 total effective membrane area) with several IEMs were evaluated. The results were converted to the power output of a pilot-scale RED stack (299 membrane pairs and 179.4 m2 total effective membrane area) via the reference IEMs. The use of low-area-resistance IEMs resulted in lower internal resistance and higher power density. The power density was 2.3 times higher than that of the reference IEMs when natural SW was used. The net power output was expected to be approximately 230 W with a pilot-scale RED stack using low-area-resistance IEMs and natural SW. This value is one of the indicators of the output of a large RED stack and is a target to be exceeded with further improvements in the RED system. Full article
(This article belongs to the Special Issue State-of-the-Art Membrane Science and Technology in Japan 2021, 2022)
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