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Membranes
Volume 14
Issue 1
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Membranes, Volume 14, Issue 1 (January 2024) – 26 articles

Cover Story (view full-size image): This study is the first to demonstrate a high-degree concentration organic solvent forward osmosis (OSFO) for pharmaceutical pre-concentration. A polyketone-based thin-film composite hollow fiber membrane with a polyamide selective layer on the bore surface was used as the OSFO membrane. Methanol, sucrose octaacetate (SoA), and 2 M polyethylene glycol 400 (PEG-400)/MeOH solution were used as the solvent, model active pharmaceutical ingredient, and a draw solution (DS), respectively. The 11 wt% SoA/MeOH solution was concentrated to 52 wt% without any SoA leakage into the DS. However, the final feed solution contained 17 wt% PEG-400. This study shows the promising potential of OSFO for pharmaceutical pre-concentration and the technical problems that need to be solved for social implementation. View this paper
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23 pages, 1058 KiB  
Article
Bovine Serum Albumin Rejection by an Open Ultrafiltration Membrane: Characterization and Modeling
by Eric Suryawirawan, Anja E. M. Janssen, Remko M. Boom and Albert van der Padt
Membranes 2024, 14(1), 26; https://doi.org/10.3390/membranes14010026 - 21 Jan 2024
Viewed by 1578
Abstract
The classic application of ultrafiltration (UF) is for the complete retention of proteins, and in that situation, the transport behavior is well established. More open membranes with fractional retention are used when separating different proteins. However, protein transport has not been well documented [...] Read more.
The classic application of ultrafiltration (UF) is for the complete retention of proteins, and in that situation, the transport behavior is well established. More open membranes with fractional retention are used when separating different proteins. However, protein transport has not been well documented yet in the literature. The bovine serum albumin (∼69 kDa) observed rejection ranges from 0.65 to 1 using a 300 kDa molecular weight cut-off membrane at different pH, ionic strength, and pressure. We demonstrated that, especially with open UF, the transport of proteins through the membrane is dominated by advection, with insignificant diffusion effects (p value > 0.05). We showed that with open UF, retention is not only caused by size exclusion but also to a large extent by electrostatic interactions and oligomerization of the proteins. Mass transfer in the polarization layer was relatively independent of the pH and ionic strength. It was underestimated by common Sherwood relations due to a relatively large contribution of the reduction in the flow turbulence near the membrane by the removal of fluid through the membrane. We propose a model that allows relatively quick characterization of the rejection of proteins without prior knowledge of the pore sizes and charges based on just a limited set of experiments. Therefore, protein rejection with the open UF system can be targeted by tuning the processing conditions, which might be useful for designing protein fractionation processes. Full article
(This article belongs to the Section Membrane Processing and Engineering)
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23 pages, 3142 KiB  
Review
Review of Hybrid Membrane Distillation Systems
by Heng Zhang and Haizhen Xian
Membranes 2024, 14(1), 25; https://doi.org/10.3390/membranes14010025 - 18 Jan 2024
Cited by 1 | Viewed by 1693
Abstract
Membrane distillation (MD) is an attractive separation process that can work with heat sources with low temperature differences and is less sensitive to concentration polarization and membrane fouling than other pressure-driven membrane separation processes, thus allowing it to use low-grade thermal energy, which [...] Read more.
Membrane distillation (MD) is an attractive separation process that can work with heat sources with low temperature differences and is less sensitive to concentration polarization and membrane fouling than other pressure-driven membrane separation processes, thus allowing it to use low-grade thermal energy, which is helpful to decrease the consumption of energy, treat concentrated solutions, and improve water recovery rate. This paper provides a review of the integration of MD with waste heat and renewable energy, such as solar radiation, salt-gradient solar ponds, and geothermal energy, for desalination. In addition, MD hybrids with pressure-retarded osmosis (PRO), multi-effect distillation (MED), reverse osmosis (RO), crystallization, forward osmosis (FO), and bioreactors to dispose of concentrated solutions are also comprehensively summarized. A critical analysis of the hybrid MD systems will be helpful for the research and development of MD technology and will promote its application. Eventually, a possible research direction for MD is suggested. Full article
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14 pages, 1804 KiB  
Review
The Application of Membrane Separation Technology in the Pharmaceutical Industry
by Ruirui Ma, Juan Li, Ping Zeng, Liang Duan, Jimin Dong, Yunxia Ma and Lingkong Yang
Membranes 2024, 14(1), 24; https://doi.org/10.3390/membranes14010024 - 17 Jan 2024
Cited by 1 | Viewed by 2423
Abstract
With the advancement in membrane technology, membrane separation technology has been found increasingly widespread applications in the pharmaceutical industry. It is utilized in drug separation and purification, wastewater treatment, and the recycling of wastewater resources. This study summarizes the application history of membrane [...] Read more.
With the advancement in membrane technology, membrane separation technology has been found increasingly widespread applications in the pharmaceutical industry. It is utilized in drug separation and purification, wastewater treatment, and the recycling of wastewater resources. This study summarizes the application history of membrane technology in the pharmaceutical industry, presents practical engineering examples of its applications, analyzes the various types of membrane technologies employed in the pharmaceutical sector, and finally, highlights the application cases of renowned international and Chinese membrane technology companies in the pharmaceutical field. Full article
(This article belongs to the Special Issue Sustainable Membrane Technologies for Wastewater Treatment)
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28 pages, 2689 KiB  
Review
Green Synthesis of Cation Exchange Membranes: A Review
by Stef Depuydt and Bart Van der Bruggen
Membranes 2024, 14(1), 23; https://doi.org/10.3390/membranes14010023 - 17 Jan 2024
Cited by 1 | Viewed by 2419
Abstract
Cation exchange membranes (CEMs) play a significant role in the transition to a more sustainable/green society. They are important components for applications such as water electrolysis, artificial photosynthesis, electrodialysis and fuel cells. Their synthesis, however, is far from being sustainable, affecting safety, health [...] Read more.
Cation exchange membranes (CEMs) play a significant role in the transition to a more sustainable/green society. They are important components for applications such as water electrolysis, artificial photosynthesis, electrodialysis and fuel cells. Their synthesis, however, is far from being sustainable, affecting safety, health and the environment. This review discusses and evaluates the possibilities of synthesizing CEMs that are more sustainable and green. First, the concepts of green and sustainable chemistry are discussed. Subsequently, this review discusses the fabrication of conventional perfluorinated CEMs and how they violate the green/sustainability principles, eventually leading to environmental and health incidents. Furthermore, the synthesis of green CEMs is presented by dividing the synthesis into three parts: sulfonation, material selection and solvent selection. Innovations in using gaseous SO3 or gas–liquid interfacial plasma technology can make the sulfonation process more sustainable. Regarding the selection of polymers, chitosan, cellulose, polylactic acid, alginate, carrageenan and cellulose are promising alternatives to fossil fuel-based polymers. Finally, water is the most sustainable solvent and many biopolymers are soluble in it. For other polymers, there are a limited number of studies using green solvents. Promising solvents are found back in other membrane, such as dimethyl sulfoxide, Cyrene™, Rhodiasolv® PolarClean, TamiSolve NxG and γ-valerolactone. Full article
(This article belongs to the Special Issue Electrochemical Membranes: Materials, Characterization, Testing, and Cleaning)
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13 pages, 6584 KiB  
Article
Effect of Long-Term Sodium Hypochlorite Cleaning on Silicon Carbide Ultrafiltration Membranes Prepared via Low-Pressure Chemical Vapor Deposition
by Asif Jan, Mingliang Chen, Michiel Nijboer, Mieke W. J. Luiten-Olieman, Luuk C. Rietveld and Sebastiaan G. J. Heijman
Membranes 2024, 14(1), 22; https://doi.org/10.3390/membranes14010022 - 15 Jan 2024
Viewed by 1842
Abstract
Sodium hypochlorite (NaClO) is widely used for the chemical cleaning of fouled ultrafiltration (UF) membranes. Various studies performed on polymeric membranes demonstrate that long-term (>100 h) exposure to NaClO deteriorates the physicochemical properties of the membranes, leading to reduced performance and service life. [...] Read more.
Sodium hypochlorite (NaClO) is widely used for the chemical cleaning of fouled ultrafiltration (UF) membranes. Various studies performed on polymeric membranes demonstrate that long-term (>100 h) exposure to NaClO deteriorates the physicochemical properties of the membranes, leading to reduced performance and service life. However, the effect of NaClO cleaning on ceramic membranes, particularly the number of cleaning cycles they can undergo to alleviate irreversible fouling, remains poorly understood. Silicon carbide (SiC) membranes have garnered widespread attention for water and wastewater treatment, but their chemical stability in NaClO has not been studied. Low-pressure chemical vapor deposition (LP-CVD) provides a simple and economical route to prepare/modify ceramic membranes. As such, LP-CVD facilitates the preparation of SiC membranes: (a) in a single step; and (b) at much lower temperatures (700–900 °C) in comparison with sol-gel methods (ca. 2000 °C). In this work, SiC ultrafiltration (UF) membranes were prepared via LP-CVD at two different deposition temperatures and pressures. Subsequently, their chemical stability in NaClO was investigated over 200 h of aging. Afterward, the properties and performance of as-prepared SiC UF membranes were evaluated before and after aging to determine the optimal deposition conditions. Our results indicate that the SiC UF membrane prepared via LP-CVD at 860 °C and 100 mTorr exhibited excellent resistance to NaClO aging, while the membrane prepared at 750 °C and 600 mTorr significantly deteriorated. These findings not only highlight a novel preparation route for SiC membranes in a single step via LP-CVD, but also provide new insights about the careful selection of LP-CVD conditions for SiC membranes to ensure their long-term performance and robustness under harsh chemical cleaning conditions. Full article
(This article belongs to the Special Issue Inorganic Membranes for Energy and Environmental Applications)
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17 pages, 14440 KiB  
Article
Inducing Deep Sweeps and Vortex Ejections on Patterned Membrane Surfaces to Mitigate Surface Fouling
by August H. Young, Nico Hotz, Brian T. Hawkins and Zbigniew J. Kabala
Membranes 2024, 14(1), 21; https://doi.org/10.3390/membranes14010021 - 13 Jan 2024
Viewed by 1413
Abstract
Patterned membrane surfaces offer a hydrodynamic approach to mitigating concentration polarization and subsequent surface fouling. However, when subjected to steady crossflow conditions, surface patterns promote particle accumulation in the recirculation zones of cavity-like spaces. In order to resolve this issue, we numerically subject [...] Read more.
Patterned membrane surfaces offer a hydrodynamic approach to mitigating concentration polarization and subsequent surface fouling. However, when subjected to steady crossflow conditions, surface patterns promote particle accumulation in the recirculation zones of cavity-like spaces. In order to resolve this issue, we numerically subject a two-dimensional, patterned membrane surface to a rapidly pulsed crossflow. When combined with cavity-like spaces, such as the valleys of membrane surface patterns, a rapidly pulsed flow generates mixing mechanisms (i.e., the deep sweep and the vortex ejection) and disrupts recirculation zones. In only four pulses, we demonstrate the ability of these mechanisms to remove over half of the particles trapped in recirculation zones via massless particle tracking studies (i.e., numerical integration of the simulated velocity field). The results of this work suggest that when combined with a rapidly pulsed inlet flow, patterned membrane surfaces can not only alleviate concentration polarization and the surface fouling that follows but also reduce the need for traditional cleaning methods that require operational downtime and often involve the use of abrasive chemical agents. Full article
(This article belongs to the Special Issue Theoretical Study of Membrane Processes)
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19 pages, 7825 KiB  
Article
Theoretical Analysis of the Influence of Spacers on Salt Ion Transport in Electromembrane Systems Considering the Main Coupled Effects
by Anna Kovalenko, Makhamet Urtenov, Vladimir Chekanov and Natalya Kandaurova
Membranes 2024, 14(1), 20; https://doi.org/10.3390/membranes14010020 - 10 Jan 2024
Viewed by 1344
Abstract
This article considers a theoretical analysis of the influence of the main coupled effects and spacers on the transfer of salt ions in electromembrane systems (EMS) using a 2D mathematical model of the transfer process in a desalting channel with spacers based on [...] Read more.
This article considers a theoretical analysis of the influence of the main coupled effects and spacers on the transfer of salt ions in electromembrane systems (EMS) using a 2D mathematical model of the transfer process in a desalting channel with spacers based on boundary value problems for the coupled system of Nernst–Planck–Poisson and Navier–Stokes equations. The basic patterns of salt ion transport have been established, taking into account diffusion, electromigration, forced convection, electroconvection, dissociation/recombination reactions of water molecules, as well as spacers located inside the desalting channel. It has been shown that spacers and taking into account the dissociation/recombination reaction of water molecules significantly change both the formation and development of electroconvection. This article confirms the fact of the exaltation of the limiting current studied by Harkatz, where it is shown that the current (flux) of salt ions increases when the dissociation reaction begins by a certain value called the exaltation current, which is proportional to the flow of water dissociation products. A significant combined effect of electroconvection and dissociation/recombination reactions as well as the spacer system in the desalting channel on the transport of salt ions are shown. The complex, nonlinear, and non-stationary interaction of all the main effects of concentration polarization and spacers in the desalting channel are also considered in the work. Full article
(This article belongs to the Special Issue Theoretical Study of Membrane Processes)
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13 pages, 3382 KiB  
Article
A Comprehensive Study on the Effect of Plasticizers on the Characteristics of Polymer Inclusion Membranes (PIMs): Exploring Butyl Stearate as a Promising Alternative
by Berta Alcalde, Gemma Elias, Spas D. Kolev, José Alberto Méndez, Sergi Díez, Helena Oliver-Ortega, Enriqueta Anticó and Clàudia Fontàs
Membranes 2024, 14(1), 19; https://doi.org/10.3390/membranes14010019 - 09 Jan 2024
Viewed by 1607
Abstract
This study investigated the influence of various plasticizers commonly used in the manufacture of polymer inclusion membranes (PIMs), such as 2-nitrophenyl octyl ether (NPOE), phthalates, adipates, and sebacates on the mechanical, thermal, and transport properties of membranes. Additionally, butyl stearate (BTS), chosen for [...] Read more.
This study investigated the influence of various plasticizers commonly used in the manufacture of polymer inclusion membranes (PIMs), such as 2-nitrophenyl octyl ether (NPOE), phthalates, adipates, and sebacates on the mechanical, thermal, and transport properties of membranes. Additionally, butyl stearate (BTS), chosen for its non-toxic nature compared to phthalates and its cost-effectiveness relative to adipates and sebacates, was evaluated as a plasticizer in PIMs for the first time. All plasticizers were incorporated in PIMs made of either cellulose triacetate (CTA) or poly(vinyl chloride) (PVC) as the base polymers and the task-specific ionic liquid trioctylmethylammonium thiosalicylate (TOMATS) as the carrier. The plasticizers were found to significantly affect the characteristics of membrane hydrophilicity, mechanical flexibility, and thermal stability. Transport experiments using Hg(II) as a model target ion revealed that, for CTA-based PIMs, the plasticizer did not significantly affect transport efficiency. However, for PVC-based PIMs, BTS exhibited better efficiency when compared to NPOE. These findings highlight the potential of BTS as an attractive alternative to currently used plasticizers in PVC-based PIM formulations. Full article
(This article belongs to the Special Issue Feature Papers in Membrane Analysis and Characterization)
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13 pages, 2453 KiB  
Article
Cannabidiol Strengthening of Gastric Tight Junction Complexes Analyzed in an Improved Xenopus Oocyte Assay
by Laura Stein, Marie-Luise Vollstaedt and Salah Amasheh
Membranes 2024, 14(1), 18; https://doi.org/10.3390/membranes14010018 - 08 Jan 2024
Viewed by 1601
Abstract
Cannabidiol (CBD), the non-psychoactive compound derived from the cannabis plant, has gained attention in recent years as a remedy against gastrointestinal disorders ranging from nausea and inflammation to abdominal pain. Recent advances demonstrated an effect on inflammatory pathways and barrier proteins. However, information [...] Read more.
Cannabidiol (CBD), the non-psychoactive compound derived from the cannabis plant, has gained attention in recent years as a remedy against gastrointestinal disorders ranging from nausea and inflammation to abdominal pain. Recent advances demonstrated an effect on inflammatory pathways and barrier proteins. However, information on possible direct effects is scarce and needs to be addressed, as applications are currently increasing in popularity. To accomplish this, we have employed Xenopus laevis oocytes as a heterologous expression system for analysis of the direct effects on stomach-specific claudins and further developed tight junction (TJ) protein interaction assays. Human claudin-4, claudin-5, and claudin-18.2 were expressed in Xenopus oocytes, clustered in pairs to form contact areas, and analyzed in a two-cell model approach, including measurement of the contact area and contact strength. CLDN4/5/18 + CLDN4/5/18 oocyte pairs were incubated with 20 µM CBD or with 40 µM CBD and were compared to cells without CBD treatment (ctrl). For interaction analysis, the contact area was measured after 24 h and 48 h. Whereas CBD did not affect the size of the protein interaction area, Double Orbital Challenge experiments revealed an increased contact strength after 24 h incubation with CBD. In addition, the Xenopus oocyte experiments were accompanied by an analysis of claudin-4, -5, and -18 expression in gastric epithelium by immunoblotting and immunohistochemistry. Claudin-4, -5, and -18 were strongly expressed, indicating a major role for gastric epithelial barrier function. In summary, our study shows direct effects of 40 µM CBD on Xenopus oocytes heterologously expressing a stomach-specific claudin combination, indicating a supportive and beneficial effect of CBD on gastric TJ proteins. Full article
(This article belongs to the Special Issue The Xenopus Oocyte: A Tool for Membrane Biology, Second Edition)
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16 pages, 5171 KiB  
Article
Promising Fluorine-Free Ion Exchange Membranes Based on a Poly(ether-block-amide) Copolymer and Sulfonated Montmorillonite: Influence of Different Copolymer Segment Ratios
by Manhal H. Ibrahim Al-Mashhadani, Khirdakhanim Salmanzade, András Tompos and Asmaa Selim
Membranes 2024, 14(1), 17; https://doi.org/10.3390/membranes14010017 - 06 Jan 2024
Viewed by 1761
Abstract
Novel composite membranes employing a poly(ether-block-amide) (PEBAX) copolymer and sulfonated montmorillonite (S-MMT) as a filler were developed. The ratio of polyether to polyamide blocks was investigated using PEBAX 2533 and PEBAX 4533 based on the membrane properties and performance. Additionally, the effect of [...] Read more.
Novel composite membranes employing a poly(ether-block-amide) (PEBAX) copolymer and sulfonated montmorillonite (S-MMT) as a filler were developed. The ratio of polyether to polyamide blocks was investigated using PEBAX 2533 and PEBAX 4533 based on the membrane properties and performance. Additionally, the effect of the changing filler ratio was monitored. The interaction between the S-MMT as nanofiller and the polymer matrix of PEBAX2533 and PEBAX4533 as well as the crystalline nature and thermal and mechanical stability of the composite membranes were evaluated using Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and tensile test. The composite membrane with 7 wt.% S-MMT showed the highest water uptake of 21% and 16% and an acceptable swelling degree of 16% and 9% for PEBAX 2533 and PEBAX 4533 composite membranes, respectively. In terms of water uptake and ion exchange capacity at room temperature, the new un-protonated membranes are superior to un-protonated Nafion. Meanwhile, with the same S-MMT content, the ion conductivity of PEBAX 2533 and PEBAX 4533 composite membranes is 2 and 1.6 mS/cm, and their ion exchange capacity is 0.9 and 1.10 meq/g. Full article
(This article belongs to the Special Issue Advanced Polymeric Membranes for Fuel Cell Applications)
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13 pages, 1984 KiB  
Article
Green Preparation and Functional Properties of Reinforced All-Cellulose Membranes Made from Corn Straw
by Wentao Zhang, Tianhao Wang, Zeming Jiang, Xin Gao, Changxia Sun and Liping Zhang
Membranes 2024, 14(1), 16; https://doi.org/10.3390/membranes14010016 - 05 Jan 2024
Viewed by 1535
Abstract
In this study, all-cellulose nanocomposite (ACNC) was successfully prepared through a green and sustainable approach by using corn stalk as raw material, water as regeneration solvent, and recyclable two-component ionic liquid/DMSO as the solvent to dissolve cellulose. The morphology and structural properties of [...] Read more.
In this study, all-cellulose nanocomposite (ACNC) was successfully prepared through a green and sustainable approach by using corn stalk as raw material, water as regeneration solvent, and recyclable two-component ionic liquid/DMSO as the solvent to dissolve cellulose. The morphology and structural properties of ACNC were determined by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analysis, indicating homogeneity and good crystallinity. In addition, a comprehensive characterization of ACNC showed that CNF not only improved the thermal stability and mechanical characteristics of ACNC, but also significantly improved the oxygen barrier performance. The ACNC prepared in this work has a good appearance, smooth surface, and good optical transparency, which provides a potential application prospect for converting cellulose wastes such as corn straws into biodegradable packaging materials and electronic device encapsulation materials. Full article
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20 pages, 3398 KiB  
Article
Phase-Dependent Adsorption of Myelin Basic Protein to Phosphatidylcholine Lipid Bilayers
by Petra Maleš, Zlatko Brkljača, Ivo Crnolatac, Dražen Petrov and Danijela Bakarić
Membranes 2024, 14(1), 15; https://doi.org/10.3390/membranes14010015 - 04 Jan 2024
Viewed by 1517
Abstract
The dense packing of opposite cytoplasmic surfaces of the lipid-enriched myelin membrane, responsible for the proper saltatory conduction of nerve impulses through axons, is ensured by the adhesive properties of myelin basic protein (MBP). Although preferentially interacting with negatively charged phosphatidylserine (PS) lipids, [...] Read more.
The dense packing of opposite cytoplasmic surfaces of the lipid-enriched myelin membrane, responsible for the proper saltatory conduction of nerve impulses through axons, is ensured by the adhesive properties of myelin basic protein (MBP). Although preferentially interacting with negatively charged phosphatidylserine (PS) lipids, as an intrinsically disordered protein, it can easily adapt its shape to its immediate environment and thus adsorb to domains made of zwitterionic phosphatidylcholine (PC) lipids. As the molecular-level interaction pattern between MBP and PC lipid membranes suffers from scarce characterization, an experimental and computational study of multilamellar liposomes (MLVs) composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) in the presence of bovine MBP is presented here. Calorimetric and temperature-dependent UV-Vis measurements identified DPPC pretransition temperature (Tp) and calorimetric enthalpy (ΔHcal) as the physicochemical parameters most responsive to the presence of MBP. Besides suggesting an increase in β-sheet fractions of structured MBP segments as DPPC lipids undergo from the gel (20 °C) to the fluid (50 °C) phase, FTIR spectra unraveled the significant contribution of lysine (Lys) residues in the adsorption pattern, especially when DPPC is in the fluid (50 °C) phase. In addition to highlighting the importance of Lys residues in the MBP adsorption on DPPC lipid bilayer, employing salt bridges (SBs) and hydrogen bonds (HBs), MD data suggest the crucial importance of the orientation of MBP with respect to the surface of the DPPC lipid bilayer. Full article
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13 pages, 4179 KiB  
Article
High-Degree Concentration Organic Solvent Forward Osmosis for Pharmaceutical Pre-Concentration
by Ryoichi Takada, Ryosuke Takagi and Hideto Matsuyama
Membranes 2024, 14(1), 14; https://doi.org/10.3390/membranes14010014 - 04 Jan 2024
Viewed by 1441
Abstract
Over half of the pharmaceutical industry’s capital investments are related to the purification of active pharmaceutical ingredients (APIs). Thus, a cost-effective purification process with a highly concentrated solution is urgently required. In addition, the purification process should be nonthermal because most APIs and [...] Read more.
Over half of the pharmaceutical industry’s capital investments are related to the purification of active pharmaceutical ingredients (APIs). Thus, a cost-effective purification process with a highly concentrated solution is urgently required. In addition, the purification process should be nonthermal because most APIs and their intermediates are temperature-sensitive. This study investigated a high-degree concentration organic solvent forward osmosis (OSFO) membrane process. A polyketone-based thin-film composite hollow fiber membrane with a polyamide selective layer on the bore surface was used as the OSFO membrane to achieve a high tolerance for organic solvents and an effective concentration. MeOH, sucrose octaacetate (SoA), and 2M polyethylene glycol 400 (PEG-400)/MeOH solution were used as the solvent, model API, and a draw solution (DS), respectively. OSFO was performed at room temperature (23 ± 3 °C). Consequently, the 11 wt% SoA/MeOH solution was concentrated to 52 wt% without any SoA leakage into the DS. To our knowledge, there are no studies in which up to a 5 wt% concentration by OSFO has been demonstrated. However, the final feed solution contained 17 wt% PEG-400. This study demonstrates the promising potential of OSFO for pharmaceutical pre-concentration and the technical problems that need to be solved for social implementation. Full article
(This article belongs to the Special Issue Development and Application of Membrane Separation Processes, 2nd Edition)
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12 pages, 3044 KiB  
Article
Efficiency, Kinetics and Mechanism of 4-Nitroaniline Removal from Aqueous Solutions by Emulsion Liquid Membranes Using Type 1 Facilitated Transport
by Gerardo León, Asunción María Hidalgo, María Gómez, Elisa Gómez and Beatriz Miguel
Membranes 2024, 14(1), 13; https://doi.org/10.3390/membranes14010013 - 01 Jan 2024
Cited by 1 | Viewed by 1384
Abstract
4-Nitroaniline (4NA) is a common organic pollutant that is released into the environment during the manufacture and processing of a wide variety of industrial products. This article describes the use of an emulsion liquid membrane process to remove 4NA from aqueous solutions using [...] Read more.
4-Nitroaniline (4NA) is a common organic pollutant that is released into the environment during the manufacture and processing of a wide variety of industrial products. This article describes the use of an emulsion liquid membrane process to remove 4NA from aqueous solutions using a type 1 facilitated transport mechanism. Optimization of the removal process was carried out by analyzing the efficiency of 4NA removal from the feed phase and the initial apparent feed/membrane fluxes and permeabilities under different experimental conditions. The kinetics of the removal process was analyzed using a simplified mass transfer model involving an empirical mass transfer coefficient calculated from experimental data, assuming that the concentrations of 4NA in the external aqueous phase and in the internal w/o emulsion are uniform. The results show that there is a very good fit between the experimental and model data and that the variation in the values of the overall mass transfer coefficients with the experimental conditions coincides with that of the removal efficiency mentioned above. The transport mechanism was studied by identifying the rate-controlling step of the removal process, using models described for adsorption processes, due to the strong parallelism between the transport mechanisms in adsorption and emulsion liquid membrane processes. Full article
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15 pages, 2946 KiB  
Article
Antibacterial Activity Assessment of Chitosan/Alginate Lavender Essential Oil Membranes for Biomedical Applications
by Encarnación Cruz Sánchez, María Teresa García, Ignacio Gracia, Soledad Illescas Fernández-Bermejo, Juan Francisco Rodríguez, Jesús Manuel García-Vargas and Dolors Vidal Roig
Membranes 2024, 14(1), 12; https://doi.org/10.3390/membranes14010012 - 01 Jan 2024
Viewed by 1933
Abstract
The demand for natural products in the treatment of dermatological pathologies has boosted the use of bioactive substances such as lavender essential oil (LEO), which stands out for its anti-inflammatory and antioxidant properties and its antimicrobial potential. Biopolymers such as chitosan (CHT) and [...] Read more.
The demand for natural products in the treatment of dermatological pathologies has boosted the use of bioactive substances such as lavender essential oil (LEO), which stands out for its anti-inflammatory and antioxidant properties and its antimicrobial potential. Biopolymers such as chitosan (CHT) and alginate (ALG) are biodegradable and biocompatible and have proven their viability in biomedical applications such as skin regeneration. The inhibitory effect of LEO on the growth of skin-related bacterial species Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa and the fungus Candida albicans was studied by incorporating 1% v/v LEO encapsulated in CHT, ALG, and CHT/ALG membranes. Despite the verification of the antimicrobial effect of all type of membranes, no synergistic effect was observed following the addition of LEO. S. aureus and P. aeruginosa showed the most growth on the different substrates and C. albicans demonstrated the highest inhibition. This is a first approach using microorganisms isolated from clinical samples or skin microbiota. Further investigation would be advisable using more clinical strains for each microorganism to validate their biomedical applicability. Full article
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18 pages, 6152 KiB  
Article
Graphene Oxide–Polyphenylsulfone Nanocomposite Beads for Paracetamol Removal from Aqueous Solution
by Mansour Alhoshan, Arun Kumar Shukla, Javed Alam and Ali Awadh Hamid
Membranes 2024, 14(1), 9; https://doi.org/10.3390/membranes14010009 - 28 Dec 2023
Viewed by 1455
Abstract
This study introduces a promising and practical method for the removal of paracetamol from aqueous environments, employing graphene oxide–polymer nanocomposite beads. The approach involves the utilization of a straightforward and facile phase inversion method, offering a convenient and efficient one-step process for the [...] Read more.
This study introduces a promising and practical method for the removal of paracetamol from aqueous environments, employing graphene oxide–polymer nanocomposite beads. The approach involves the utilization of a straightforward and facile phase inversion method, offering a convenient and efficient one-step process for the creation of adsorbent beads by integrating polymers and graphene oxide (GO). The synthesized nanocomposite beads are tailored for the removal of paracetamol from simulated wastewater in batch systems. Extensive characterization techniques including XPS, FTIR, SEM, TGA, and zeta potential analysis are employed to scrutinize the chemical properties and structural attributes of the prepared beads. The investigation explores the impact of critical parameters such as adsorbent dosage, adsorption duration, initial paracetamol concentration, and solution pH on the adsorption process. These nanocomposite beads exhibit an exceptional paracetamol removal efficiency, achieving up to 99% removal. This research not only contributes to the advancement of efficient and sustainable adsorbent materials for pollutant removal but also underscores their potential for environmentally friendly and cost-effective solutions in the domain of wastewater treatment. Full article
(This article belongs to the Special Issue Recent Advances in 2D Material-Based Membranes)
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31 pages, 6562 KiB  
Review
There Are No Insurmountable Barriers: Passage of the Helicobacter pylori VacA Toxin from Bacterial Cytoplasm to Eukaryotic Cell Organelle
by Miroslaw Jarzab and Joanna Skorko-Glonek
Membranes 2024, 14(1), 11; https://doi.org/10.3390/membranes14010011 - 28 Dec 2023
Viewed by 1586
Abstract
The Gram-negative bacterium Helicobacter pylori is a very successful pathogen, one of the most commonly identified causes of bacterial infections in humans worldwide. H. pylori produces several virulence factors that contribute to its persistence in the hostile host habitat and to its pathogenicity. [...] Read more.
The Gram-negative bacterium Helicobacter pylori is a very successful pathogen, one of the most commonly identified causes of bacterial infections in humans worldwide. H. pylori produces several virulence factors that contribute to its persistence in the hostile host habitat and to its pathogenicity. The most extensively studied are cytotoxin-associated gene A (CagA) and vacuolating cytotoxin A (VacA). VacA is present in almost all H. pylori strains. As a secreted multifunctional toxin, it assists bacterial colonization, survival, and proliferation during long-lasting infections. To exert its effect on gastric epithelium and other cell types, VacA undergoes several modifications and crosses multiple membrane barriers. Once inside the gastric epithelial cell, VacA disrupts many cellular-signaling pathways and processes, leading mainly to changes in the efflux of various ions, the depolarization of membrane potential, and perturbations in endocytic trafficking and mitochondrial function. The most notable effect of VacA is the formation of vacuole-like structures, which may lead to apoptosis. This review focuses on the processes involved in VacA secretion, processing, and entry into host cells, with a particular emphasis on the interaction of the mature toxin with host membranes and the formation of transmembrane pores. Full article
(This article belongs to the Special Issue Advanced Research on Structure-Function Relationships of Membrane Proteins, 2nd Edition)
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11 pages, 3032 KiB  
Article
Morphology, Cytotoxicity, and Antimicrobial Activity of Electrospun Polycaprolactone Biomembranes with Gentamicin and Nano-Hydroxyapatite
by Ioana-Codruta Mirica, Gabriel Furtos, Marioara Moldovan, Doina Prodan, Ioan Petean, Radu-Septimiu Campian, Emoke Pall and Ondine Lucaciu
Membranes 2024, 14(1), 10; https://doi.org/10.3390/membranes14010010 - 28 Dec 2023
Cited by 1 | Viewed by 1359
Abstract
The aim of this research is to develop new nanocomposite membranes (NMs) for guided bone regeneration from polycaprolactone (PCL), with different concentrations of gentamicin sulfate (GEN) and nano-hydroxyapatite (nHAP) through electrospinning. The obtained NMs were characterized for structure through SEM and AFM, which [...] Read more.
The aim of this research is to develop new nanocomposite membranes (NMs) for guided bone regeneration from polycaprolactone (PCL), with different concentrations of gentamicin sulfate (GEN) and nano-hydroxyapatite (nHAP) through electrospinning. The obtained NMs were characterized for structure through SEM and AFM, which revealed the influence of GEN and nHAP on the fiber diameter. The addition of GEN lowered the fiber diameter, and the addition of nHAP increased the diameter of the fibers. The NMs demonstrated antibacterial properties against P. aeruginosa, S. aureus, B. cereus, and E. coli depending on the drug concentration, while being negligibly affected by the nHAP content. NM cytotoxicity assessment, performed once using the MTT assay, revealed no cytotoxicity. The developed NMs could be a promising alternative for guided bone regeneration. Full article
(This article belongs to the Special Issue Nanofibrous Membrane for Biomedical, Environmental and Energy Application)
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22 pages, 4306 KiB  
Article
Bis(triethoxysilyl)ethane (BTESE)–Organosilica Membranes for H2O/DMF Separation in Reverse Osmosis (RO): Evaluation and Correlation of Subnanopores via Nanopermporometry (NPP), Modified Gas Translation (mGT) and RO Performance
by Suhaina Mohd Ibrahim, Ken-ichi Sawamura, Kengo Mishina, Xin Yu, Feridoun Salak, Shigeru Miyata, Norihiro Moriyama, Hiroki Nagasawa, Masakoto Kanezashi and Toshinori Tsuru
Membranes 2024, 14(1), 8; https://doi.org/10.3390/membranes14010008 - 26 Dec 2023
Viewed by 1676
Abstract
A 40 cm length Bis(triethoxysilyl)ethane (BTESE) membrane having different pore sizes was successfully prepared by changing the number of coating times for gas permeation (GP) and organic solvent reverse osmosis (OSRO) separation study. It was found that BTESE-6 membranes prepared through six-time coating [...] Read more.
A 40 cm length Bis(triethoxysilyl)ethane (BTESE) membrane having different pore sizes was successfully prepared by changing the number of coating times for gas permeation (GP) and organic solvent reverse osmosis (OSRO) separation study. It was found that BTESE-6 membranes prepared through six-time coating consisted of small-sized pores in the range 0.56 to 0.64 nm estimated using modified Gas Translation (mGT) method and 0.59 to 0.67 nm estimated by nanopermporometry (NPP) method, respectively. These membranes demonstrated a high DMF rejection, RDMF > 95% with total flux, Jv total > 5 kg m−2 h−1 at operating condition feed pressure, Pf: 8 MPa; feed temperature, Tf : 50 °C; and feed flowrate, Qf : 30 mL/min; and they exhibited a high degree selectivity of He/SF6 in the range of ~ 260–3400 at a permeation temperature 200 °C. On the other hand, the larger pore sizes of the BTESE-4 membranes (pore size estimates > 0.76 nm to 1.02 nm) exhibited low DMF rejection and a low degree selectivity of He/SF6 around ~30% and 25, respectively, at the same operating condition as BTESE-6. Both GT and NPP methods can be considered as an indicator of the measurement membrane pore size. From this study, it was found that He and SF6 gases can be some of the potential predictors for water and DMF permeance. Furthermore, by comparing our OSRO membrane with other PV membranes for DMF/H2O separation, our BTESE-6 membranes still exhibited high flux in the range of 3–6 kg m−2 h−1 with a separation factor H2O/DMF in the range of 80–120. Full article
(This article belongs to the Section Membrane Processing and Engineering)
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14 pages, 3363 KiB  
Article
Thin Film Nanocomposite Membranes Based on Zeolitic Imidazolate Framework-8/Halloysite Nanotube Composites
by Yan Wang, Shaofan Duan, Huixian Wang, Can Wei, Lijuan Qin, Guanying Dong and Yatao Zhang
Membranes 2024, 14(1), 7; https://doi.org/10.3390/membranes14010007 - 25 Dec 2023
Viewed by 1455
Abstract
Thin film nanocomposite (TFN) membranes have proven their unrivaled value, as they can combine the advantages of different materials and furnish membranes with improved selectivity and permeability. The development of TFN membranes has been severely limited by the poor dispersion of the nanoparticles [...] Read more.
Thin film nanocomposite (TFN) membranes have proven their unrivaled value, as they can combine the advantages of different materials and furnish membranes with improved selectivity and permeability. The development of TFN membranes has been severely limited by the poor dispersion of the nanoparticles and the weak adhesion between the nanoparticles and the polymer matrix. In this study, to address the poor dispersion of nanoparticles in TFN membranes, we proposed a new combination of m-ZIF-8 and m-HNTs, wherein the ZIF-8 and HNTs were modified with poly (sodium p-styrenesulfonate) to enhance their dispersion in water. Furthermore, the hydropathic properties of the membranes can be well controlled by adjusting the content of m-ZIF-8 and m-HNTs. A series of modified m-ZIF-8/m-HNT/PAN membranes were prepared to modulate the dye/salt separation performance of TFN membranes. The experimental results showed that our m-ZIF-8/m-HNT/PAN membranes can elevate the water flux significantly up to 42.6 L m−2 h−1 MPa−1, together with a high rejection of Reactive Red 49 (more than 80%). In particular, the optimized NFM-7.5 membrane that contained 7.5 mg of HNTs and 2.5 mg of ZIF-8 showed a 97.1% rejection of Reactive Red 49 and 21.3% retention of NaCl. Full article
(This article belongs to the Section Membrane Preparation and Characterization)
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11 pages, 1517 KiB  
Article
Comparison of Anion-Exchange Membranes for Diffusion Dialysis of Mixtures of Acids and Their Iron Salts
by Helena Bendová, Libor Dušek and Jiří Palarčík
Membranes 2024, 14(1), 6; https://doi.org/10.3390/membranes14010006 - 24 Dec 2023
Viewed by 1515
Abstract
This study presents the possibility of using diffusion dialysis for the separation of inorganic acids (hydrochloric, nitric, and hydrofluoric) and their ferric salts whose composition corresponds to that of real spent pickling solutions. At a steady state, the transport properties of three different [...] Read more.
This study presents the possibility of using diffusion dialysis for the separation of inorganic acids (hydrochloric, nitric, and hydrofluoric) and their ferric salts whose composition corresponds to that of real spent pickling solutions. At a steady state, the transport properties of three different anion-exchange membranes (Fumasep-FAD, Neosepta-AFN, and Neosepta-AHA) are compared using a continuous counter-current dialyzer. At a constant composition of the solutions (acid concentration 3 mol L−1 and iron concentration 30–40 g L−1), the effects of volumetric liquid flow rates on the transport rate of H+ and Fe3+ ions through the membrane are studied. The dialysis process is characterized by the recovery of acids and the rejection of salts. Furthermore, the values of the dialysis coefficients of acids, iron, and the acid/iron separation factors are calculated and compared. The volumetric flow rates of the inlet streams change in limits from 3 × 10−8 to 6 × 10−8 m3 s−1 (from 3 to 6 L h−1 m−2, relative to the membrane area). A comparison of the tested membranes shows slightly better results for acid recovery, iron rejection, and acid/iron separation factors for the Fumasep-FAD membrane than for the Neosepta-AFN membrane. However, the results obtained show that both of these anion-exchange membranes can be considered good separators for tested mixtures that simulate real spent pickling solutions, and there is a good precondition for using diffusion dialysis for processing these solutions in industrial practice. On the contrary, very low values of acid recovery and the overall dialysis coefficient of acid are found for the Neosepta-AHA membrane in the test range of the volumetric flow rate, and, thus, this membrane is insufficient for the adequate separation of these acids and iron salts. Full article
(This article belongs to the Collection New Challenges in Membranes for Water and Wastewater Application)
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18 pages, 627 KiB  
Review
A Review of Temperature Effects on Membrane Filtration
by Bochao Xu, Wa Gao, Baoqiang Liao, Hao Bai, Yuhang Qiao and Walter Turek
Membranes 2024, 14(1), 5; https://doi.org/10.3390/membranes14010005 - 24 Dec 2023
Viewed by 2417
Abstract
Membrane technology plays a vital role in drinking water and wastewater treatments. Among a number of factors affecting membrane performance, temperature is one of the dominant factors determining membrane performance. In this review, the impact of temperature on membrane structure, fouling, chemical cleaning, [...] Read more.
Membrane technology plays a vital role in drinking water and wastewater treatments. Among a number of factors affecting membrane performance, temperature is one of the dominant factors determining membrane performance. In this review, the impact of temperature on membrane structure, fouling, chemical cleaning, and membrane performance is reviewed and discussed with a particular focus on cold temperature effects. The findings from the literature suggest that cold temperatures have detrimental impacts on membrane structure, fouling, and chemical cleaning, and thus could negatively affect membrane filtration operations and performance, while warm and hot temperatures might expand membrane pores, increase membrane flux, improve membrane chemical cleaning efficiency, and interfere with biological processes in membrane bioreactors. The research gaps, challenges, and directions of temperature effects are identified and discussed indepth. Future studies focusing on the impact of temperature on membrane processes used in water and wastewater treatment and the development of methods that could reduce the adverse effect of temperature on membrane operations are needed. Full article
(This article belongs to the Special Issue Modeling, Simulation and Application of Membrane Processes for Water Treatment 2.0)
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18 pages, 7701 KiB  
Article
Dynamics Management of Intermediate Water Storage in an Air-Breathing Single-Cell Membrane Electrode Assembly
by Avinash Kumar, Alex Schechter and Idit Avrahami
Membranes 2024, 14(1), 4; https://doi.org/10.3390/membranes14010004 - 22 Dec 2023
Viewed by 1461
Abstract
In air-breathing proton exchange membrane fuel cells (Air PEM FCs), a high rate of water evaporation from the cathode might influence the resistance of the membrane electrode assembly (MEA), which is highly dependent on the water content of the Nafion membrane. We propose [...] Read more.
In air-breathing proton exchange membrane fuel cells (Air PEM FCs), a high rate of water evaporation from the cathode might influence the resistance of the membrane electrode assembly (MEA), which is highly dependent on the water content of the Nafion membrane. We propose a dead-end hydrogen anode as a means of intermediate storage of water/humidity for self-humidification of the membrane. Such an inflatable bag integrated with a single lightweight MEA FC has the potential in blimp applications for anode self-humidification. A dynamic numerical water balance model, validated by experimental measurements, is derived to predict the effect of MEA configuration, and the membrane’s hydration state and water transfer rate at the anode on MEA resistance and performance. The experimental setup included humidity measurements, and polarization and electrochemical impedance spectroscopy tests to quantify the effect of membrane hydration on its resistance in a lightweight MEA (12 g) integrated with an inflatable dead-end hydrogen storage bag. Varying current densities (5, 10, and 15 mA/cm2) and cathode humidity levels (20, 50, and 80%) were examined and compared with the numerical results. The validated model predicts that the hydration state of the membrane and water transfer rate at the anode can be increased by using a thin membrane and thicker gas diffusion layer. Full article
(This article belongs to the Section Membrane Applications)
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17 pages, 8985 KiB  
Article
An Energy–Economic–Environment Tri-Objective Evaluation Method for Gas Membrane Separation Processes of H2/CO2
by Junjiang Bao, Shuai Li, Xiaopeng Zhang and Ning Zhang
Membranes 2024, 14(1), 3; https://doi.org/10.3390/membranes14010003 - 21 Dec 2023
Viewed by 1426
Abstract
For pre-combustion carbon capture, the high syngas pressure provides a sufficient mass transfer driving force to make the gas membrane separation process an attractive option. Comparisons of combined different membrane materials (H2-selective and CO2-selective membranes) and membrane process layouts [...] Read more.
For pre-combustion carbon capture, the high syngas pressure provides a sufficient mass transfer driving force to make the gas membrane separation process an attractive option. Comparisons of combined different membrane materials (H2-selective and CO2-selective membranes) and membrane process layouts are very limited. Especially, the multi-objective optimization of such processes requires further investigation. Therefore, this paper proposes 16 two-stage combined membranes system for pre-combustion CO2 capture, including 4 two-stage H2-selective membrane systems, 4 two-stage CO2-selective membrane systems, and 8 two-stage hybrid membrane systems. A tri-objective optimization method of energy, economy, and environment is proposed for comprehensive evaluation of the proposed systems. Results show that with the targets of 90% CO2 purity and recovery, six gas membrane separation systems could be satisfied. After further multi-objective optimization and comparison, the C1H2-4 system (the hybrid system with H2-selective membranes and CO2-selective membranes) has the best performance. Feed composition and separation requirements also have an important influence on the multi-objective optimization results. The effects of selectivity and permeance of H2-selective and CO2-selective membranes on the performance of the C1H2-4 system are also significant. Full article
(This article belongs to the Special Issue Separation of Greenhouse Gases Using Hollow Fiber Membrane Contactor)
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16 pages, 1850 KiB  
Article
Nisin Purification from a Cell-Free Supernatant by Electrodialysis in a Circular Economy Framework
by Alexandre Rulence, Véronique Perreault, Jacinthe Thibodeau, Loubna Firdaous, Ismail Fliss and Laurent Bazinet
Membranes 2024, 14(1), 2; https://doi.org/10.3390/membranes14010002 (registering DOI) - 21 Dec 2023
Viewed by 1486
Abstract
Nisin, an antimicrobial peptide produced by Lactococcus lactis strains, is a promising natural preservative for the food industry and an alternative to antibiotics for the pharmaceutical industry against Gram-positive bacteria. Nisin purification is commonly performed using salting out and chromatographic techniques, which are [...] Read more.
Nisin, an antimicrobial peptide produced by Lactococcus lactis strains, is a promising natural preservative for the food industry and an alternative to antibiotics for the pharmaceutical industry against Gram-positive bacteria. Nisin purification is commonly performed using salting out and chromatographic techniques, which are characterized by their low yields, the use of solvents and the production of large volumes of effluents. In the present work, the purification of nisin from a cell-free supernatant (CFS), after the production of nisin by fermentation on a whey permeate medium, was studied using ammonium sulfate precipitation and electrodialysis (ED) as a promising eco-friendly process for nisin purification. Results showed an increase in nisin precipitation using a 40% ammonium sulfate saturation (ASS) level with a purification fold of 73.8 compared with 34.5 and no purification fold for a 60% and 20% ASS level, respectively. The results regarding nisin purification using ED showed an increase in nisin purification and concentration fold, respectively, of 21.8 and 156 when comparing the final product to the initial CFS. Nisin-specific activity increased from 75.9 ± 4.4 to 1652.7 ± 236.8 AU/mg of protein. These results demonstrated the effectiveness of ED coupled with salting out for nisin purification compared with common techniques. Furthermore, the process was noteworthy for its relevance in a circular economy scheme, as it does not require any solvents and avoids generating polluting effluents. It can be employed for the purification of nisin and the recovery of salts from salting out, facilitating their reuse in a circular economy. Full article
(This article belongs to the Special Issue Ion-Exchange Membranes and Processes, Fourth Edition)
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25 pages, 5133 KiB  
Article
A Selective Separation Mechanism for Mono/divalent Cations and Properties of a Hollow-Fiber Composite Nanofiltration Membrane Having a Positively Charged Surface
by Enlin Wang, Xinghua Lv, Shaoxiao Liu, Qiang Dong, Jiayue Li, Honghai Li and Baowei Su
Membranes 2024, 14(1), 1; https://doi.org/10.3390/membranes14010001 (registering DOI) - 20 Dec 2023
Viewed by 1491
Abstract
Positively charged nanofiltration (NF) technology is considered a green and low-cost method for mono/divalent cation separation. Nevertheless, the separation rejection mechanisms of these NF membranes have yet to be extensively investigated. In this work, we fabricated a thin-film composite (TFC) hollow-fiber (HF) NF [...] Read more.
Positively charged nanofiltration (NF) technology is considered a green and low-cost method for mono/divalent cation separation. Nevertheless, the separation rejection mechanisms of these NF membranes have yet to be extensively investigated. In this work, we fabricated a thin-film composite (TFC) hollow-fiber (HF) NF membrane with a positively charged surface via modification of the nascent interfacial polymerization layer using a branched polyethyleneimine (BPEI)/ethanol solution. Then, we extensively investigated its selective separation mechanism for mono/divalent cations. We proposed and proved that there exists a double-charged layer near the membrane surface, which helps to repel the divalent cations selectively via Donnan exclusion while promoting the fast penetration of monovalent cations. Meanwhile, the membrane skin layer is loose and hydrophilic due to the loose BPEI structure and the abundance of amine groups, as well as the changed fabrication conditions. In this way, we achieved very good mono/divalent cation selectivity and relatively high water permeance for the as-prepared HF NF membrane. We also obtained good anti-fouling, anti-scaling, and acid resistance, and long-term stability as well, which are urgently needed during practical application. Furthermore, we successfully amplified this HF NF membrane and proved that it has broad application prospects in mono/divalent cation separation. Full article
(This article belongs to the Special Issue Hollow Fiber Membrane Technology and Applications)
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