Membranes

13 pages, 2069 KiB

Open AccessArticle

Structural and Functional Characterization of the Newly Designed Antimicrobial Peptide Crabrolin21

by Francesca Cantini, Paola Giannì, Sara Bobone, Cassandra Troiano, Hugo van Ingen, Renato Massoud, Nicoletta Perini, Luciana Migliore, Philippe Savarin, Charles Sanders, Lorenzo Stella and Marco Sette

Membranes 2023, 13(3), 365; https://doi.org/10.3390/membranes13030365 - 22 Mar 2023

Cited by 2 | Viewed by 1986

Abstract

(1) Background: antimicrobial resistance is becoming a dramatic problem for public health, and the design of new antimicrobial agents is an active research area. (2) Methods: based on our previous work, we designed an improved version of the crabrolin peptide and characterized its [...] Read more.

(1) Background: antimicrobial resistance is becoming a dramatic problem for public health, and the design of new antimicrobial agents is an active research area. (2) Methods: based on our previous work, we designed an improved version of the crabrolin peptide and characterized its functional and structural properties with a wide range of techniques. (3) Results: the newly designed peptide, crabrolin21, is much more active than the previous ones and shows specific selectivity towards bacterial cells. (4) Conclusions: crabrolin21 shows interesting properties and deserves further studies. Full article

(This article belongs to the Special Issue Biological Membrane and Bioactive Compounds Interactions)

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22 pages, 9347 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Fabrication of Anatase TiO₂/PVDF Composite Membrane for Oil-in-Water Emulsion Separation and Dye Photocatalytic Degradation

by Chengcai Li, Hewei Yu, Biao Huang, Guojin Liu, Yuhai Guo, Hailin Zhu and Bin Yu

Membranes 2023, 13(3), 364; https://doi.org/10.3390/membranes13030364 - 22 Mar 2023

Cited by 8 | Viewed by 2805

Abstract

At present, the types of pollutants in wastewater are more and more complicated, however, the multifunctional membrane materials are in short supply. To prepare a membrane with both high efficient oil-in-water emulsion separation performance and photocatalytic degradation performance of organic dyes, the bifunctional [...] Read more.

At present, the types of pollutants in wastewater are more and more complicated, however, the multifunctional membrane materials are in short supply. To prepare a membrane with both high efficient oil-in-water emulsion separation performance and photocatalytic degradation performance of organic dyes, the bifunctional separation membrane was successfully prepared by electrostatic spinning technology of PVDF/PEMA and in situ deposition of anatase TiO₂ nanoparticles containing Ti³⁺ and oxygen vacancies (O_v). The prepared composite membrane has excellent hydrophilic properties (WCA = 15.65), underwater oleophobic properties (UOCA = 156.69), and photocatalytic performance. These composite membranes have high separation efficiency and outstanding anti-fouling performance, the oil removal efficiency reaches 98.95%, and the flux recovery rate (FRR) reaches 99.19% for soybean oil-in-water emulsion. In addition, the composite membrane has outstanding photocatalytic degradation performance, with 97% and 90.2% degradation of RhB and AG-25 under UV conditions, respectively. Several oil-in-water separation and dye degradation experiments show that the PVDF composite membrane has excellent reuse performance. Based on these results, this study opens new avenues for the preparation of multifunctional reusable membranes for the water treatment field. Full article

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17 pages, 4779 KiB

Open AccessArticle

Interplay between Forced Convection and Electroconvection during the Overlimiting Ion Transport through Anion-Exchange Membranes: A Fourier Transform Analysis of Membrane Voltage Drops

by Lorena Hernández-Pérez, Manuel César Martí-Calatayud, Maria Teresa Montañés and Valentín Pérez-Herranz

Membranes 2023, 13(3), 363; https://doi.org/10.3390/membranes13030363 - 21 Mar 2023

Cited by 7 | Viewed by 1614

Abstract

Electrodialysis (ED) applications have expanded in recent years and new modes of operation are being investigated. Operation at overlimiting currents involves the phenomenon of electroconvection, which is associated with the generation of vortices. These vortices accelerate the process of solution mixing, making it [...] Read more.

Electrodialysis (ED) applications have expanded in recent years and new modes of operation are being investigated. Operation at overlimiting currents involves the phenomenon of electroconvection, which is associated with the generation of vortices. These vortices accelerate the process of solution mixing, making it possible to increase the transport of ions across the membranes. In this work, frequency analysis is applied to investigate the interaction between different parameters on the development of electroconvection near anion-exchange membranes, which would provide a basis for the development of ED systems with favored electroconvection. Chronopotentiometric curves are registered and Fast Fourier Transform analysis is carried out to study the amplitude of the transmembrane voltage oscillations. Diverse behaviors are detected as a function of the level of forced convection and current density. The synergistic combination of forced convection and overlimiting currents leads to an increase in the signal amplitude, which is especially noticeable at frequencies around 0.1 Hz. Fast Fourier Transform analysis allows identifying, for a given system, the conditions that lead to a transition between stable and chaotic electroconvection modes. Full article

(This article belongs to the Special Issue Electrochemical Membranes: Materials, Characterization, Testing, and Cleaning)

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23 pages, 10281 KiB

Open AccessArticle

UNILIPID, a Methodology for Energetically Accurate Prediction of Protein Insertion into Implicit Membranes of Arbitrary Shape

by André Lanrezac and Marc Baaden

Membranes 2023, 13(3), 362; https://doi.org/10.3390/membranes13030362 - 21 Mar 2023

Cited by 1 | Viewed by 1934

Abstract

The insertion of proteins into membranes is crucial for understanding their function in many biological processes. In this work, we present UNILIPID, a universal implicit lipid-protein description as a methodology for dealing with implicit membranes. UNILIPID is independent of the scale of representation [...] Read more.

The insertion of proteins into membranes is crucial for understanding their function in many biological processes. In this work, we present UNILIPID, a universal implicit lipid-protein description as a methodology for dealing with implicit membranes. UNILIPID is independent of the scale of representation and can be applied at the level of all atoms, coarse-grained particles down to the level of a single bead per amino acid. We provide example implementations for these scales and demonstrate the versatility of our approach by accurately reflecting the free energy of transfer for each amino acid. In addition to single membranes, we describe the analytical implementation of double membranes and show that UNILIPID is well suited for modeling at multiple scales. We generalize to membranes of arbitrary shape. With UNILIPID, we provide a methodological framework for a simple and general parameterization tuned to reproduce a selected reference hydrophobicity scale. The software we provide along with the methodological description is optimized for specific user features such as real-time response, live visual analysis, and virtual reality experiences. Full article

(This article belongs to the Collection Feature Papers in Membranes in Life Sciences)

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12 pages, 2087 KiB

Open AccessArticle

A Simple, Semi-Quantitative Acyl Biotin Exchange-Based Method to Detect Protein S-Palmitoylation Levels

by Valentina Buffa, Giorgia Adamo, Sabrina Picciotto, Antonella Bongiovanni and Daniele P. Romancino

Membranes 2023, 13(3), 361; https://doi.org/10.3390/membranes13030361 - 21 Mar 2023

Cited by 1 | Viewed by 2707

Abstract

Protein S-palmitoylation is a reversible post-translational lipidation in which palmitic acid (16:0) is added to protein cysteine residue by a covalent thioester bond. This modification plays an active role in membrane targeting of soluble proteins, protein–protein interaction, protein trafficking, and subcellular localization. Moreover, [...] Read more.

Protein S-palmitoylation is a reversible post-translational lipidation in which palmitic acid (16:0) is added to protein cysteine residue by a covalent thioester bond. This modification plays an active role in membrane targeting of soluble proteins, protein–protein interaction, protein trafficking, and subcellular localization. Moreover, palmitoylation is related to different diseases, such as neurodegenerative pathologies, cancer, and developmental defects. The aim of this research is to provide a straightforward and sensitive procedure to detect protein palmitoylation based on Acyl Biotin Exchange (ABE) chemistry. Our protocol setup consists of co-immunoprecipitation of native proteins (i.e., CD63), followed by the direct detection of palmitoylation on proteins immobilized on polyvinylidene difluoride (PVDF) membranes. With respect to the conventional ABE-based protocol, we optimized and validated a rapid semi-quantitative assay that is shown to be significantly more sensitive and highly reproducible. Full article

(This article belongs to the Special Issue Membrane Interaction between Lipids, Proteins and Peptides)

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16 pages, 3073 KiB

Open AccessArticle

Pharmacological Characterization of a Recombinant Mitochondrial ROMK2 Potassium Channel Expressed in Bacteria and Reconstituted in Planar Lipid Bilayers

by Milena Krajewska, Adam Szewczyk, Bogusz Kulawiak and Piotr Koprowski

Membranes 2023, 13(3), 360; https://doi.org/10.3390/membranes13030360 - 21 Mar 2023

Viewed by 2246

Abstract

In the inner mitochondrial membrane, several potassium channels that play a role in cell life and death have been identified. One of these channels is the ATP-regulated potassium channel (mitoK_ATP). The ROMK2 potassium channel is a potential molecular component of the [...] Read more.

In the inner mitochondrial membrane, several potassium channels that play a role in cell life and death have been identified. One of these channels is the ATP-regulated potassium channel (mitoK_ATP). The ROMK2 potassium channel is a potential molecular component of the mitoK_ATP channel. The current study aimed to investigate the pharmacological modulation of the activity of the ROMK2 potassium channel expressed in Escherichia coli bacteria. ROMK2 was solubilized in polymer nanodiscs and incorporated in planar lipid bilayers. The impact of known mitoK_ATP channel modulators on the activity of the ROMK2 was characterized. We found that the ROMK2 channel was activated by the mitoK_ATP channel opener diazoxide and blocked by mitoK_ATP inhibitors such as ATP/Mg²⁺, 5-hydroxydecanoic acid, and antidiabetic sulfonylurea glibenclamide. These results indicate that the ROMK2 potassium protein may be a pore-forming subunit of mitoK_ATP and that the impact of channel modulators is not related to the presence of accessory proteins. Full article

(This article belongs to the Special Issue Biological Membrane and Bioactive Compounds Interactions)

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15 pages, 10314 KiB

Open AccessArticle

Effects of Porous Supports in Thin-Film Composite Membranes on CO₂ Separation Performances

by Hongfang Guo, Wenqi Xu, Jing Wei, Yulei Ma, Zikang Qin, Zhongde Dai, Jing Deng and Liyuan Deng

Membranes 2023, 13(3), 359; https://doi.org/10.3390/membranes13030359 - 21 Mar 2023

Cited by 5 | Viewed by 2641

Abstract

Despite numerous publications on membrane materials and the fabrication of thin-film composite (TFC) membranes for CO₂ separation in recent decades, the effects of porous supports on TFC membrane performance have rarely been reported, especially when humid conditions are concerned. In this work, [...] Read more.

Despite numerous publications on membrane materials and the fabrication of thin-film composite (TFC) membranes for CO₂ separation in recent decades, the effects of porous supports on TFC membrane performance have rarely been reported, especially when humid conditions are concerned. In this work, six commonly used porous supports were investigated to study their effects on membrane morphology and the gas transport properties of TFC membranes. Two common membrane materials, Pebax and poly(vinyl alcohol) (PVA), were employed as selective layers to make sample membranes. The fabricated TFC membranes were tested under humid conditions, and the effect of water vapor on gas permeation in the supports was studied. The experiments showed that all membranes exhibited notably different performances under dry or humid conditions. For polyacrylonitrile (PAN) and poly(ether sulfones) (PESF) membranes, the water vapor easily condenses in the pores of these supports, thus sharply increasing the mass transfer resistance. The effect of water vapor is less in the case of polyvinylidene difluoride (PVDF) and polysulfone (PSF), showing better long-term stability. Porous supports significantly contribute to the overall mass transfer resistance. The presence of water vapor worsens the mass transfer in the porous support due to the pore condensation and support material swelling. The membrane fabrication condition must be optimized to avoid pore condensation and maintain good separation performance. Full article

(This article belongs to the Section Membrane Applications)

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18 pages, 7179 KiB

Open AccessArticle

Clean Energy Based Multigeneration System for Sustainable Cities: Thermodynamic, and Stability Analyses

by Uzair Bhatti, Hamza Aamir, Khurram Kamal, Tahir Abdul Hussain Ratlamwala, Fahad Alqahtani, Mohammed Alkahtani, Emad Mohammad and Moath Alatefi

Membranes 2023, 13(3), 358; https://doi.org/10.3390/membranes13030358 - 20 Mar 2023

Cited by 3 | Viewed by 1904

Abstract

This paper concerns the development and analysis of multigeneration systems based on hybrid sources such as biomass and wind. Industry requires different types of sources to provide several outputs, so the goal of this research was to fulfill the industrial requirement with optimization. [...] Read more.

This paper concerns the development and analysis of multigeneration systems based on hybrid sources such as biomass and wind. Industry requires different types of sources to provide several outputs, so the goal of this research was to fulfill the industrial requirement with optimization. The multigeneration cycle supplies enough power to satiate energy demands, i.e., power, cooling, hydrogen, air conditioning, freshwater, hot water, and heating. For this, the multigeneration cycle was modeled in the Engineering Equation Solver (EES) and Simulink to obtain optimized results for the industry. Energy and exergy for the multigeneration cycle were determined to assess the performance of the cycle and to investigate the optimized results for the overall system. This study shows that for configuration selection and design, different thermodynamic, economic, and environmental aspects should be considered. Based on the results, the selection of the best location for this multigeneration system was made. Power output from the wind turbine was around 7 MW and from biogas 0.6 MW. The overall exergy efficiency of the multigeneration system was found to be 0.1401. Full article

(This article belongs to the Special Issue Modeling and Simulation of Industrial and Environmental Membrane Technologies)

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23 pages, 8310 KiB

Open AccessArticle

Novel MXene-Modified Polyphenyl Sulfone Membranes for Functional Nanofiltration of Heavy Metals-Containing Wastewater

by Mohammed Azeez Naji, Hamed Salimi-Kenari, Qusay F. Alsalhy, Raed A. Al-Juboori, Ngoc Huynh, Khalid T. Rashid and Issam K. Salih

Membranes 2023, 13(3), 357; https://doi.org/10.3390/membranes13030357 - 20 Mar 2023

Cited by 10 | Viewed by 2425

Abstract

In this work, MXene as a hydrophilic 2D nanosheet has been suggested to tailor the polyphenylsulfone (PPSU) flat sheet membrane characteristics via bulk modification. The amount of MXene varied in the PPSU casting solution from 0–1.5 wt.%, while a series of characterization tools [...] Read more.

In this work, MXene as a hydrophilic 2D nanosheet has been suggested to tailor the polyphenylsulfone (PPSU) flat sheet membrane characteristics via bulk modification. The amount of MXene varied in the PPSU casting solution from 0–1.5 wt.%, while a series of characterization tools have been employed to detect the surface characteristics changes. This included atomic force microscopy (AFM), scanning electron microscopy (SEM), contact angle, pore size and porosity, and Fourier-transform infrared spectroscopy (FTIR). Results disclosed that the MXene content could significantly influence some of the membranes’ surface characteristics while no effect was seen on others. The optimal MXene content was found to be 0.6 wt.%, as revealed by the experimental work. The roughness parameters of the 0.6 wt.% nanocomposite membrane were notably enhanced, while greater hydrophilicity has been imparted compared to the nascent PPSU membrane. This witnessed enhancement in the surface characteristics of the nanocomposite was indeed reflected in their performance. A triple enhancement in the pure water flux was witnessed without compromising the retention of the membranes against the Cu²⁺, Cd²⁺ and Pd²⁺ feed. In parallel, high, and comparable separation rates (>92%) were achieved by all membranes regardless of the MXene content. In addition, promising antifouling features were observed with the nanocomposite membranes, disclosing that these nanocomposite membranes could offer a promising potential to treat heavy metals-containing wastewater for various applications. Full article

(This article belongs to the Special Issue Membranes for Industrial Wastewater Treatment)

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17 pages, 4565 KiB

Open AccessArticle

Physicochemical Characteristics of Model Membranes Composed of Legionella gormanii Lipids

by Katarzyna Pastuszak, Elżbieta Chmiel, Bożena Kowalczyk, Jacek Tarasiuk, Małgorzata Jurak and Marta Palusińska-Szysz

Membranes 2023, 13(3), 356; https://doi.org/10.3390/membranes13030356 - 20 Mar 2023

Cited by 4 | Viewed by 2041

Abstract

Legionella gormanii is one of the species belonging to the genus Legionella, which causes atypical community-acquired pneumonia. The most important virulence factors that enable the bacteria to colonize the host organism are associated with the cell surface. Lipids building the cell envelope [...] Read more.

Legionella gormanii is one of the species belonging to the genus Legionella, which causes atypical community-acquired pneumonia. The most important virulence factors that enable the bacteria to colonize the host organism are associated with the cell surface. Lipids building the cell envelope are crucial not only for the membrane integrity of L. gormanii but also by virtue of being a dynamic site of interactions between the pathogen and the metabolites supplied by its host. The utilization of exogenous choline by the Legionella species results in changes in the lipids’ composition, which influences the physicochemical properties of the cell surface. The aim of this study was to characterize the interfacial properties of the phospholipids extracted from L. gormanii cultured with (PL+choline) and without exogenous choline (PL−choline). The Langmuir monolayer technique coupled with the surface potential (SPOT) sensor and the Brewster angle microscope (BAM) made it possible to prepare the lipid monomolecular films (model membranes) and study their properties at the liquid/air interface at 20 °C and 37 °C. The results indicate the effect of the choline addition to the bacterial medium on the properties of the L. gormanii phospholipid membranes. The differences were revealed in the organization of monolayers, their molecular packing and ordering, degree of condensation and changes in the components’ miscibility. These findings are the basis for further research on the mechanisms of adaptation of this pathogen, which by changing the native composition and properties of lipids, bypasses the action of antimicrobial compounds and avoids the host immune attack. Full article

(This article belongs to the Special Issue Advances in Model Membrane Systems)

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13 pages, 2599 KiB

Open AccessArticle

Removal of Typical PPCPs by Reverse Osmosis Membranes: Optimization of Treatment Process by Factorial Design

by Jianing Liu, Liang Duan, Qiusheng Gao, Yang Zhao and Fu Gao

Membranes 2023, 13(3), 355; https://doi.org/10.3390/membranes13030355 - 20 Mar 2023

Cited by 11 | Viewed by 2299

Abstract

In this paper, the removal effect of reverse osmosis (RO) on three common pharmaceuticals and personal care products (PPCPs), including ibuprofen (IBU), carbamazepine (CBZ), and triclosan (TCS), were compared under different process conditions, and the removal rate of PPCPs, membrane flux, and PPCPs [...] Read more.

In this paper, the removal effect of reverse osmosis (RO) on three common pharmaceuticals and personal care products (PPCPs), including ibuprofen (IBU), carbamazepine (CBZ), and triclosan (TCS), were compared under different process conditions, and the removal rate of PPCPs, membrane flux, and PPCPs membrane adsorption capacity were analyzed. The removal rate increased with the increase of the influent concentration and pre-membrane pressure, while pH influenced the removal effect of different PPCPs by affecting the electrostatic interaction between pollutants and membranes. It was also found that the dynamic adsorption of PPCPs on RO membranes under different conditions complied with the pseudo-first-order reaction kinetic adsorption model. The maximum stable adsorption capacity and the adsorption rate of PPCPs on membranes under various conditions were simulated based on the model. Moreover, through factorial design, the removal rates of RO on IBU, CBZ, and TCS could reach 98.93%, 97.47%, and 99.01%, respectively, under the optimal conditions (with an influent concentration of 500 μg/L, pre-membrane pressure of 16 bar and pH = 10). By optimizing the process of removing PPCPs with the RO membrane method, the optimal process conditions of removing IBU, CBZ, and TCS with the RO membrane method were obtained, which provided reference conditions and data support for the practical application of removing PPCPs with the RO membrane method. Full article

(This article belongs to the Section Membrane Applications)

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17 pages, 4227 KiB

Open AccessArticle

Comparison of Energy Efficiency between Atmospheric Batch Pressure-Retarded Osmosis and Single-Stage Pressure-Retarded Osmosis

by Dan Li, Zijing Mo and Qianhong She

Membranes 2023, 13(3), 354; https://doi.org/10.3390/membranes13030354 - 19 Mar 2023

Cited by 3 | Viewed by 1532

Abstract

Batch pressure-retarded osmosis (PRO) with varied-pressure and multiple-cycle operation using a pressurized variable-volume tank has been proposed as a high-efficiency osmotic energy harvesting technology, but it suffers scalability constraints. In this study, a more scalable batch PRO, namely, atmospheric batch PRO (AB-PRO), was [...] Read more.

Batch pressure-retarded osmosis (PRO) with varied-pressure and multiple-cycle operation using a pressurized variable-volume tank has been proposed as a high-efficiency osmotic energy harvesting technology, but it suffers scalability constraints. In this study, a more scalable batch PRO, namely, atmospheric batch PRO (AB-PRO), was proposed, utilizing an atmospheric tank to receive and store the intermediate diluted draw solution (DS) and a pressure exchanger to recover the pressure energy from the diluted DS before being recycled into the tank. Its performance was further compared with single-stage PRO (SS-PRO) at different flow schemes via analytic models. The results show that the AB-PRO with an infinitesimal per-cycle water recovery (r) approaches the thermodynamic maximum energy production under ideal conditions, outperforming the SS-PRO with lower efficiencies caused by under-pressurization (UP). However, when considering inefficiencies, a ~40% efficiency reduction was observed in AB-PRO owing to UP and entropy generation as the optimal r is no-longer infinitesimal. Nonetheless, AB-PRO is still significantly superior to SS-PRO at low water recoveries (R) and maintains a stable energy efficiency at various R, which is conducive to meeting the fluctuating demand in practice by flexibly adjusting R. Further mitigating pressure losses and deficiencies of energy recovery devices can significantly improve AB-PRO performance. Full article

(This article belongs to the Special Issue Honorary Issue for Professor Anthony Fane)

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11 pages, 1666 KiB

Open AccessArticle

Interactions of Surfactants with Biomimetic Membranes—2. Generation of Electric Potential with Non-Ionic Surfactants

by Nikolai M. Kocherginsky and Brajendra K. Sharma

Membranes 2023, 13(3), 353; https://doi.org/10.3390/membranes13030353 - 18 Mar 2023

Cited by 1 | Viewed by 1765

Abstract

It is discovered that noncharged surfactants lead to electric effects that interact with biomimetic membranes made of nitrocellulose filters, which are impregnated with fatty acid esters. At a surfactant concentration as low as 64 microM in one of the solutions, they lead to [...] Read more.

It is discovered that noncharged surfactants lead to electric effects that interact with biomimetic membranes made of nitrocellulose filters, which are impregnated with fatty acid esters. At a surfactant concentration as low as 64 microM in one of the solutions, they lead to the transient formation of transmembrane electric potential. Maximum changes of this potential are proportional to the log of noncharged surfactant concentrations when it changes by three orders of magnitude. We explain this new and nontrivial effect in terms of an earlier suggested physicochemical mechanics approach and noncharged surfactants transient changes induced by membrane permeability for inorganic ions. It could be used to imitate the interactions of non-ionic drugs with biological membranes. The effect may also be used in determining the concentration of these surfactants and other non-ionic chemicals of concern, such as pharmaceuticals and personal care products. Full article

(This article belongs to the Special Issue Advances in Artiﬁcial and Biological Membranes, Volume II)

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12 pages, 4069 KiB

Open AccessArticle

Electroformation of Giant Unilamellar Vesicles from Damp Lipid Films Formed by Vesicle Fusion

by Zvonimir Boban, Ivan Mardešić, Sanja Perinović Jozić, Josipa Šumanovac, Witold Karol Subczynski and Marija Raguz

Membranes 2023, 13(3), 352; https://doi.org/10.3390/membranes13030352 - 18 Mar 2023

Cited by 4 | Viewed by 3053

Abstract

Giant unilamellar vesicles (GUVs) are artificial membrane models which are of special interest to researchers because of their similarity in size to eukaryotic cells. The most commonly used method for GUVs production is electroformation. However, the traditional electroformation protocol involves a step in [...] Read more.

Giant unilamellar vesicles (GUVs) are artificial membrane models which are of special interest to researchers because of their similarity in size to eukaryotic cells. The most commonly used method for GUVs production is electroformation. However, the traditional electroformation protocol involves a step in which the organic solvent is completely evaporated, leaving behind a dry lipid film. This leads to artifactual demixing of cholesterol (Chol) in the form of anhydrous crystals. These crystals do not participate in the formation of the lipid bilayer, resulting in a decrease of Chol concentration in the bilayer compared to the initial lipid solution. We propose a novel electroformation protocol which addresses this issue by combining the rapid solvent exchange, plasma cleaning and spin-coating techniques to produce GUVs from damp lipid films in a fast and reproducible manner. We have tested the protocol efficiency using 1/1 phosphatidylcholine/Chol and 1/1/1 phosphatidylcholine/sphingomyelin/Chol lipid mixtures and managed to produce a GUV population of an average diameter around 40 µm, with many GUVs being larger than 100 µm. Additionally, compared to protocols that include the dry film step, the sizes and quality of vesicles determined from fluorescence microscopy images were similar or better, confirming the benefits of our protocol in that regard as well. Full article

(This article belongs to the Special Issue Artificial Models of Biological Membranes)

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11 pages, 2651 KiB

Open AccessArticle

Using Tannic-Acid-Based Complex to Modify Polyacrylonitrile Hollow Fiber Membrane for Efficient Oil-In-Water Separation

by Micah Belle Marie Yap Ang, Wei-Lin Hsu, You-Syuan Wang, Hsin-Yu Kuo, Hui-An Tsai and Kueir-Rarn Lee

Membranes 2023, 13(3), 351; https://doi.org/10.3390/membranes13030351 - 18 Mar 2023

Cited by 1 | Viewed by 2088

Abstract

Separating oil from water allows us to reuse both fluids for various applications, leading to a more economical process. Membrane separation has been evidenced as a cost-effective process for wastewater treatment. A hollow fiber membrane made of polyacrylonitrile (PAN) is an excellent choice [...] Read more.

Separating oil from water allows us to reuse both fluids for various applications, leading to a more economical process. Membrane separation has been evidenced as a cost-effective process for wastewater treatment. A hollow fiber membrane made of polyacrylonitrile (PAN) is an excellent choice for separating oil from water because of its superior chemical resistance. Its low antifouling ability, however, reduces the effectiveness of its separation. Hence, in this study, we used tannic acid (TA) and FeIII complex to modify the surface of the PAN hollow fiber membrane. To improve membrane performance, different reaction times were investigated. The results demonstrate that even when the TA-FeIII covered the pores of the PAN membrane, the water flux remained constant. However, when an emulsion was fed to the feed solution, the flux increased from 50 to 66 LMH, indicating low oil adhesion on the surface of the modified membrane. When compared to the pristine membrane, the modified membrane had superior antifouling and reusability. As a result, the hydrophilic TA-FeIII complex on PAN surface improves overall membrane performance. Full article

(This article belongs to the Special Issue Advances in Porous and Dense Membranes: Fabrication and Applications)

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26 pages, 13229 KiB

Open AccessArticle

Hydrogen Sulphide Sequestration with Metallic Ions in Acidic Media Based on Chitosan/sEPDM/Polypropylene Composites Hollow Fiber Membranes System

by Dumitru Pașcu, Aurelia Cristina Nechifor, Vlad-Alexandru Grosu, Ovidiu Cristian Oprea, Szidonia-Katalin Tanczos, Geani Teodor Man, Florina Dumitru, Alexandra Raluca Grosu and Gheorghe Nechifor

Membranes 2023, 13(3), 350; https://doi.org/10.3390/membranes13030350 - 17 Mar 2023

Cited by 2 | Viewed by 2290

Abstract

This paper presents the preparation and characterization of composite membranes based on chitosan (Chi), sulfonated ethylene–propylene–diene terpolymer (sEPDM), and polypropylene (PPy), and designed to capture hydrogen sulfide. The Chi/sEPDM/PPy composite membranes were prepared through controlled evaporation of a toluene dispersion layer of Chi:sEPDM [...] Read more.

This paper presents the preparation and characterization of composite membranes based on chitosan (Chi), sulfonated ethylene–propylene–diene terpolymer (sEPDM), and polypropylene (PPy), and designed to capture hydrogen sulfide. The Chi/sEPDM/PPy composite membranes were prepared through controlled evaporation of a toluene dispersion layer of Chi:sEPDM 1;1, w/w, deposited by immersion and under a slight vacuum (100 mmHg) on a PPy hollow fiber support. The composite membranes were characterized morphologically, structurally, and thermally, but also from the point of view of their performance in the process of hydrogen sulfide sequestration in an acidic media solution with metallic ion content (Cu²⁺, Cd²⁺, Pb²⁺, and/or Zn²⁺). The operational parameters of the pertraction were the pH, pM, matrix gas flow rate, and composition. The results of pertraction from synthetic gases mixture (nitrogen, methane, carbon dioxide) indicated an efficient removal of hydrogen sulfide through the prepared composite membranes, as well as its immobilization as sulfides. The sequestration and the recuperative separation, as sulfides from an acid medium, of the hydrogen sulfide reached up to 96%, decreasing in the order: CuS > PbS > CdS > ZnS. Full article

(This article belongs to the Special Issue Membrane Systems for Metal Ion Extraction)

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36 pages, 6719 KiB

Open AccessArticle

Interactions of N-Mannich Bases of Pyrrolo[3,4-c]pyrrole with Artificial Models of Cell Membranes and Plasma Proteins, Evaluation of Anti-Inflammatory and Antioxidant Activity

by Łukasz Szczukowski, Jadwiga Maniewska, Benita Wiatrak, Paulina Jawień, Edward Krzyżak, Aleksandra Kotynia, Aleksandra Marciniak, Maciej Janeczek and Aleksandra Redzicka

Membranes 2023, 13(3), 349; https://doi.org/10.3390/membranes13030349 - 17 Mar 2023

Viewed by 2123

Abstract

Despite the widespread and easy access to NSAIDs, effective and safe treatment of various inflammatory disorders is still a serious challenge because of the severe adverse effects distinctive to these drugs. The Mannich base derivatives of pyrrolo[3,4-c]pyrrole are potent, preferential COX-2 [...] Read more.

Despite the widespread and easy access to NSAIDs, effective and safe treatment of various inflammatory disorders is still a serious challenge because of the severe adverse effects distinctive to these drugs. The Mannich base derivatives of pyrrolo[3,4-c]pyrrole are potent, preferential COX-2 inhibitors with a COX-2/COX-1 inhibitory ratio better than meloxicam. Therefore, we chose the six most promising molecules and subjected them to further in-depth research. The current study presents the extensive biological, spectroscopic and in silico evaluation of the activity and physicochemical properties of pyrrolo[3,4-c]pyrrole derivatives. Aware of the advantages of dual COX–LOX inhibition, we investigated the 15-LOX inhibitory activity of these molecules. We also examined their antioxidant effect in several in vitro experiments in a protection and regeneration model. Furthermore, we defined how studied compounds interact with artificial models of cell membranes, which is extremely important for drugs administered orally with an intracellular target. The interactions and binding mode of the derivatives with the most abundant plasma proteins—human serum albumin and alpha-1-acid glycoprotein—are also described. Finally, we used computational techniques to evaluate their pharmacokinetic properties. According to the obtained results, we can state that pyrrolo[3,4-c]pyrrole derivatives are promising anti-inflammatory and antioxidant agents with potentially good membrane permeability. Full article

(This article belongs to the Special Issue Biological Membrane and Bioactive Compounds Interactions)

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17 pages, 2859 KiB

Open AccessArticle

Analysis of PEM Water Electrolyzer Failure Due to Induced Hydrogen Crossover in Catalyst-Coated PFSA Membranes

by Eveline Kuhnert, Mathias Heidinger, Daniel Sandu, Viktor Hacker and Merit Bodner

Membranes 2023, 13(3), 348; https://doi.org/10.3390/membranes13030348 - 17 Mar 2023

Cited by 14 | Viewed by 7157

Abstract

Polymer electrolyte membrane water electrolysis (PEMWE) is a leading candidate for the development of a sustainable hydrogen infrastructure. The heart of a PEMWE cell is represented by the membrane electrode assembly (MEA), which consists of a polymer electrolyte membrane (PEM) with catalyst layers [...] Read more.

Polymer electrolyte membrane water electrolysis (PEMWE) is a leading candidate for the development of a sustainable hydrogen infrastructure. The heart of a PEMWE cell is represented by the membrane electrode assembly (MEA), which consists of a polymer electrolyte membrane (PEM) with catalyst layers (CLs), flow fields, and bipolar plates (BPPs). The weakest component of the system is the PEM, as it is prone to chemical and mechanical degradation. Membrane chemical degradation is associated with the formation of hydrogen peroxide due to the crossover of product gases (H₂ and O₂). In this paper, membrane failure due to H₂ crossover was addressed in a membrane-focused accelerated stress test (AST). Asymmetric H₂O and gas supply were applied to a test cell in OCV mode at two temperatures (60 °C and 80 °C). Electrochemical characterization at the beginning and at the end of testing revealed a 1.6-fold higher increase in the high-frequency resistance (HFR) at 80 °C. The hydrogen crossover was measured with a micro-GC, and the fluoride emission rate (FER) was monitored during the ASTs. A direct correlation between the FER and H₂ crossover was identified, and accelerated membrane degradation at higher temperatures was detected. Full article

(This article belongs to the Special Issue Membranes in Electrochemistry Applications 2.0)

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26 pages, 4379 KiB

Open AccessArticle

Donnan Dialysis for Recovering Ammonium from Fermentation Solutions Rich in Volatile Fatty Acids

by Kayo Santana Barros, Mónica Carvalheira, Bruno Costa Marreiros, Maria Ascensão M. Reis, João Goulão Crespo, Valentín Pérez-Herranz and Svetlozar Velizarov

Membranes 2023, 13(3), 347; https://doi.org/10.3390/membranes13030347 - 17 Mar 2023

Cited by 4 | Viewed by 2153

Abstract

For the production of polyhydroxyalkanoates (PHA) using nitrogen-rich feedstocks (e.g., protein-rich resources), the typical strategy of restricting cell growth as a means to enhance overall PHA productivity by nitrogen limitation is not applicable. In this case, a possible alternative to remove the nitrogen [...] Read more.

For the production of polyhydroxyalkanoates (PHA) using nitrogen-rich feedstocks (e.g., protein-rich resources), the typical strategy of restricting cell growth as a means to enhance overall PHA productivity by nitrogen limitation is not applicable. In this case, a possible alternative to remove the nitrogen excess (NH₄⁺/NH₃) is by applying membrane separation processes. In the present study, the use of Donnan dialysis to separate ammonium ions from volatile fatty acids present in the media for the production of PHA was evaluated. Synthetic and real feed solutions were used, applying NaCl and HCl receiver solutions separated by commercial cation-exchange membranes. For this specific purpose, Fumasep and Ralex membranes showed better performance than Ionsep. Sorption of ammonium ions occurred in the Ralex membrane, thus intensifying the ammonium extraction. The separation performances with NaCl and HCl as receiver solutions were similar, despite sorption occurring in the Ralex membrane more intensely in the presence of NaCl. Higher volumetric flow rates, NaCl receiver concentrations, and volume ratios of feed:receiver solutions enhanced the degree of ammonium recovery. The application of an external electric potential difference to the two-compartment system did not significantly enhance the rate of ammonium appearance in the receiver solution. The results obtained using a real ammonium-containing solution after fermentation of cheese whey showed that Donnan dialysis can be successfully applied for ammonium recovery from such solutions. Full article

(This article belongs to the Special Issue Ion Transport in Membranes and Membrane Systems: Modelling and Experiment)

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24 pages, 10118 KiB

Open AccessArticle

Improving Structural Homogeneity, Hydraulic Permeability, and Mechanical Performance of Asymmetric Monophasic Cellulose Acetate/Silica Membranes: Spinodal Decomposition Mix

by Fahimeh Zare, Sérgio B. Gonçalves, Mónica Faria and Maria Clara Gonçalves

Membranes 2023, 13(3), 346; https://doi.org/10.3390/membranes13030346 - 17 Mar 2023

Cited by 1 | Viewed by 1658

Abstract

In this paper, we propose an optimized protocol to synthesize reproducible, accurate, sustainable integrally skinned monophasic hybrid cellulose acetate/silica membranes for ultrafiltration. Eight different membrane compositions were studied, divided into two series, one and two, each composed of four membranes. The amount of [...] Read more.

In this paper, we propose an optimized protocol to synthesize reproducible, accurate, sustainable integrally skinned monophasic hybrid cellulose acetate/silica membranes for ultrafiltration. Eight different membrane compositions were studied, divided into two series, one and two, each composed of four membranes. The amount of silica increased from 0 wt.% up to 30 wt.% (with increments of 10 wt.%) in each series, while the solvent composition was kept constant within each series (formamide/acetone ratio equals 0.57 wt.% in series one and 0.73 wt.% in series two). The morphology of the membranes was analyzed by scanning electron microscopy and the chemical composition by Fourier transform infrared spectroscopy, in attenuated total reflection mode (FTIR-ATR). Mechanical tensile properties were determined using tensile tests, and a retest trial was performed to assess mechanical properties variability over different membrane batches. The hydraulic permeability of the membranes was evaluated by measuring pure water fluxes following membrane compaction. The membranes in series two produced with a higher formamide/acetone solvent ratio led to thicker membranes with higher hydraulic permeability values (47.2–26.39 kg·h⁻¹·m⁻²·bar⁻¹) than for the membranes in series one (40.01–19.4 kg·h⁻¹·m⁻²·bar⁻¹). Results obtained from the FTIR-ATR spectra suggest the presence of micro/nano-silica clusters in the hybrid membranes of series one, also exhibiting higher Young’s modulus values than the hybrid membranes in series two. Full article

(This article belongs to the Topic Inorganic Thin Films and Membrane Materials)

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18 pages, 5705 KiB

Open AccessArticle

Graphene-Oxide-Grafted Natural Phosphate Support as a Low-Cost Ceramic Membrane for the Removal of Anionic Dyes from Simulated Textile Effluent

by Hiba Bensalah, Ghizlane Derouich, Xifan Wang, Saad Alami Younssi and Maged F. Bekheet

Membranes 2023, 13(3), 345; https://doi.org/10.3390/membranes13030345 - 17 Mar 2023

Cited by 4 | Viewed by 2262

Abstract

A novel natural phosphate/graphene oxide (GO) composite membrane was successfully fabricated using two steps: (i) silane chemical grafting and (ii) dip-coating of a GO solution. First, the low-cost disk ceramic support used in this work was fabricated out of Moroccan natural phosphate, and [...] Read more.

A novel natural phosphate/graphene oxide (GO) composite membrane was successfully fabricated using two steps: (i) silane chemical grafting and (ii) dip-coating of a GO solution. First, the low-cost disk ceramic support used in this work was fabricated out of Moroccan natural phosphate, and its properties were thoroughly characterized. The optimized ceramic support was sintered at 1100 °C following a specific heat treatment based on thermogravimetric analysis (TGA) and differential thermal analysis (DTA); it exhibited a permeability of 953.33 L/h·m²·bar, a porosity of 24.55%, an average pore size of 2.45 μm and a flexural strength of 22.46 MPa. The morphology analysis using SEM showed that the GO layer was homogenously coated on the crack-free Moroccan phosphate support with a thickness of 2.8 μm. The Fourier transform infrared spectrometer (FT-IR) results showed that modification with silane could improve the interfacial adhesion between the GO membrane and the ceramic support. After coating with GO on the surface, the water permeability was reduced to 31.93 L/h·m²·bar (i.e., by a factor of 142). The prepared GO/ceramic composite membrane exhibited good efficiency in the rejection of a toxic azo dye Congo Red (CR) (95.2%) and for a simulated dye effluent (87.6%) under industrial conditions. The multi-cycle filtration tests showed that the rejection rate of CR dye remained almost the same for four cycles. Finally, the flux recovery was also studied. After 1 h of water cleaning, the permeate flux recovered, increased significantly, and then remained stable. Full article

(This article belongs to the Special Issue Graphene-Based Membranes: From Synthesis to Applications)

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20 pages, 2336 KiB

Open AccessArticle

SARS-CoV-2 Protein S Fusion Peptide Is Capable of Wrapping Negatively-Charged Phospholipids

by José Villalaín

Membranes 2023, 13(3), 344; https://doi.org/10.3390/membranes13030344 - 16 Mar 2023

Cited by 5 | Viewed by 2888

Abstract

COVID-19, caused by SARS-CoV-2, which is a positive-sense, single-stranded RNA enveloped virus, emerged in late 2019 and was declared a worldwide pandemic in early 2020 causing more than 600 million infections so far and more than 6 million deaths in the world. Although [...] Read more.

COVID-19, caused by SARS-CoV-2, which is a positive-sense, single-stranded RNA enveloped virus, emerged in late 2019 and was declared a worldwide pandemic in early 2020 causing more than 600 million infections so far and more than 6 million deaths in the world. Although new vaccines have been implemented, the pandemic continues to impact world health dramatically. Membrane fusion, critical for the viral entry into the host cell, is one of the main targets for the development of novel antiviral therapies to combat COVID-19. The S2 subunit of the viral S protein, a class I membrane fusion protein, contains the fusion domain which is directly implicated in the fusion mechanism. The knowledge of the membrane fusion mechanism at the molecular level will undoubtedly result in the development of effective antiviral strategies. We have used all-atom molecular dynamics to analyse the binding of the SARS-CoV-2 fusion peptide to specific phospholipids in model membranes composed of only one phospholipid plus cholesterol in the presence of either Na⁺ or Ca²⁺. Our results show that the fusion peptide is capable of binding to the membrane, that its secondary structure does not change significantly upon binding, that it tends to preferentially bind electronegatively charged phospholipids, and that it does not bind cholesterol at all. Understanding the intricacies of the membrane fusion mechanism and the molecular interactions involved will lead us to the development of antiviral molecules that will allow a more efficient battle against these viruses. Full article

(This article belongs to the Special Issue Molecular Dynamics Simulations in Biological Membrane Systems)

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30 pages, 11423 KiB

Open AccessReview

Potential of Lipid-Based Nanocarriers against Two Major Barriers to Drug Delivery—Skin and Blood–Brain Barrier

by Mohammad Sameer Khan, Sradhanjali Mohapatra, Vaibhav Gupta, Ahsan Ali, Punnoth Poonkuzhi Naseef, Mohamed Saheer Kurunian, Abdulkhaliq Ali F. Alshadidi, Md Shamsher Alam, Mohd. Aamir Mirza and Zeenat Iqbal

Membranes 2023, 13(3), 343; https://doi.org/10.3390/membranes13030343 - 16 Mar 2023

Cited by 13 | Viewed by 4146

Abstract

Over the past few years, pharmaceutical and biomedical areas have made the most astounding accomplishments in the field of medicine, diagnostics and drug delivery. Nanotechnology-based tools have played a major role in this. The implementation of this multifaceted nanotechnology concept encourages the advancement [...] Read more.

Over the past few years, pharmaceutical and biomedical areas have made the most astounding accomplishments in the field of medicine, diagnostics and drug delivery. Nanotechnology-based tools have played a major role in this. The implementation of this multifaceted nanotechnology concept encourages the advancement of innovative strategies and materials for improving patient compliance. The plausible usage of nanotechnology in drug delivery prompts an extension of lipid-based nanocarriers with a special reference to barriers such as the skin and blood–brain barrier (BBB) that have been discussed in the given manuscript. The limited permeability of these two intriguing biological barriers restricts the penetration of active moieties through the skin and brain, resulting in futile outcomes in several related ailments. Lipid-based nanocarriers provide a possible solution to this problem by facilitating the penetration of drugs across these obstacles, which leads to improvements in their effectiveness. A special emphasis in this review is placed on the composition, mechanism of penetration and recent applications of these carriers. It also includes recent research and the latest findings in the form of patents and clinical trials in this field. The presented data demonstrate the capability of these carriers as potential drug delivery systems across the skin (referred to as topical, dermal and transdermal delivery) as well as to the brain, which can be exploited further for the development of safe and efficacious products. Full article

(This article belongs to the Special Issue Drug Delivery Systems Based on Extracellular Vesicles)

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16 pages, 15203 KiB

Open AccessArticle

Features of the Degradation of the Proton-Conducting Polymer Nafion in Highly Porous Electrodes of PEM Fuel Cells

by Andrey A. Nechitailov, Polina Volovitch, Nadezhda V. Glebova and Anna Krasnova

Membranes 2023, 13(3), 342; https://doi.org/10.3390/membranes13030342 - 16 Mar 2023

Cited by 4 | Viewed by 2564

Abstract

The stability of new membrane–electrode assemblies of a proton-exchange membrane fuel cell with highly porous electrodes and low Pt loading, based on the proton-conducting polymer Nafion, was characterized in conditions of electrochemical aging. A comprehensive study of the effect of the microstructure on [...] Read more.

The stability of new membrane–electrode assemblies of a proton-exchange membrane fuel cell with highly porous electrodes and low Pt loading, based on the proton-conducting polymer Nafion, was characterized in conditions of electrochemical aging. A comprehensive study of the effect of the microstructure on the evolution of the electrochemical characteristics of the new assemblies was obtained by voltammetry, electrochemical impedance spectroscopy, X-ray powder diffraction, and scanning electron microscopy. Because high (>70%) porosity provides intensive mass transfer inside an electrode, structural-modifying additives—long carbon nanotubes—were introduced into the new electrodes. PEM fuel cells with electrodes of a conventional composition without carbon nanotubes were used for comparison. The aging of the samples was carried out according to the standard accelerated method in accordance with the DOE (Department of Energy) protocols. The results show two fundamental differences between the degradation of highly porous electrodes and traditional ones: 1. in highly porous electrodes, the size of Pt nanoparticles increases to a lesser extent due to recrystallization; 2. a more intense “washout” of Nafion and an increase in ionic resistance occur in highly porous electrodes. Mechanisms of the evolution of the characteristics of structurally modified electrodes under electrochemical aging are proposed. Full article

(This article belongs to the Special Issue Proton-Conducting Membranes)

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21 pages, 3970 KiB

Open AccessArticle

Novel Inorganic Membranes Based on Magnetite-Containing Silica Porous Glasses for Ultrafiltration: Structure and Sorption Properties

by Marina Konon, Elena Yu. Brazovskaya, Valery Kreisberg, Ekaterina Semenova, Irina G. Polyakova, Armenak Osipov and Tatiana Antropova

Membranes 2023, 13(3), 341; https://doi.org/10.3390/membranes13030341 - 15 Mar 2023

Cited by 3 | Viewed by 1933

Abstract

Porous glasses (PGs) obtained from sodium borosilicate (NBS) phase-separated glasses via leaching are promising inorganic membranes. Introducing Fe₂O₃ into NBS glasses imparts ferrimagnetic properties due to magnetite crystallization. Leaching of such glasses leads to the formation of magnetic PGs with [...] Read more.

Porous glasses (PGs) obtained from sodium borosilicate (NBS) phase-separated glasses via leaching are promising inorganic membranes. Introducing Fe₂O₃ into NBS glasses imparts ferrimagnetic properties due to magnetite crystallization. Leaching of such glasses leads to the formation of magnetic PGs with interesting electro-surface characteristics. This work aimed to investigate the process of obtaining magnetite-containing PGs from NBS glasses depending on silica content, using XRPD and Raman spectroscopy, studying the PG membranes’ structural characteristics and their sorption properties with respect to methylene blue (MB). Obtained PGs were characterized by a polymodal distribution of mesopores and a small number of micropores with specific surface area values of 32–135 m²/g and an average mesopore diameter of 5–41 nm. The kinetic data were analyzed using pseudo-first-order, pseudo-second-order, and intra-particle diffusion equations. The equilibrium isotherms were fitted with Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models. MB adsorption was found to be a complex process. The glass with the highest specific surface area demonstrated the maximum sorption capacity (10.5 mg/g). The pore size of PGs allowed them to be considered potential novel magnetic membranes for ultrafiltration. Full article

(This article belongs to the Special Issue Environmentally Friendly Approaches for Fabrication of Filtration Membranes (Volume II))

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12 pages, 3115 KiB

Open AccessArticle

Seasonal Changes in Qualitative and Quantitative Characteristics of Humic Substances in Waters of Different Genesis: Membrane Technologies and Equilibrium Processes

by Marina Dinu

Membranes 2023, 13(3), 340; https://doi.org/10.3390/membranes13030340 - 15 Mar 2023

Viewed by 1345

Abstract

Membrane filtration methods were applied in this study to research natural waters specification (and speciation). Lysimetric waters (soil waters) of background territories in different seasons are considered. Features of the change in molecular weights, elemental composition, and zeta potential of organic matter during [...] Read more.

Membrane filtration methods were applied in this study to research natural waters specification (and speciation). Lysimetric waters (soil waters) of background territories in different seasons are considered. Features of the change in molecular weights, elemental composition, and zeta potential of organic matter during fractionation from 8 μm to 100 kDa were found. The number of labile and non-labile speciation of some elements obtained by membrane filtration and ion-exchange separation methods were found and compared. The highest molecular weights of organic substances were found in summer samples of lysimetric waters (more than 100 kDa) with a predominance of the aromatic component in the IR spectra of the samples. Several maxima were also found in the molecular weight distribution, including the increase in autochthonous organic substances. The most stable negative zeta potential, as a stabilized colloid matter, are represented in summer (near −26 mV) and in autumn (near −22 mV) lysimetric water. A slight increase in metal ions bound into organic complexes is typical for summer and autumn samples. Full article

(This article belongs to the Special Issue Ion-Exchange Membranes and Processes, Fourth Edition)

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15 pages, 4596 KiB

Open AccessArticle

Techno-Economic Analysis of Vacuum Membrane Distillation for Seawater Desalination

by Hassaan Idrees, Sara Ali, Muhammad Sajid, Muhammad Rashid, Fahad Iqbal Khawaja, Zaib Ali and Muhammad Nabeel Anwar

Membranes 2023, 13(3), 339; https://doi.org/10.3390/membranes13030339 - 15 Mar 2023

Cited by 6 | Viewed by 3381

Abstract

Seawater desalination is an affordable and viable solution to the growing freshwater scarcity problem in water scarce regions. The current study focuses on cost analysis of Vacuum Membrane Distillation (VMD) setup for removing salts from water. The membrane used in the flat sheet [...] Read more.

Seawater desalination is an affordable and viable solution to the growing freshwater scarcity problem in water scarce regions. The current study focuses on cost analysis of Vacuum Membrane Distillation (VMD) setup for removing salts from water. The membrane used in the flat sheet VMD module was Polytetrafluoroethylene (PTFE) with 250 mm × 200 mm dimensions and 165 µm thickness. The experiments were carried out with variations in parameters such as velocity, pressure, concentration, and temperature. For the cost analysis, the operational, maintenance, instrumentation, and capital cost of the lab model was considered and then upscaled. A range of experiments was performed for NaCl and KCl under variations of operating parameters. It was noted that, for the NaCl solution, the increase in temperature from 50 °C to 70 °C doubled the permeate flux. However, for the conditions tested, the concentration shift from 0.25 M to 0.75 M decreased the permeate flux by 1.4% because the increase in ion concentrations along the membrane lowers the vapor pressure, restricting the permeate flux. The results trend for the KCl solution was similar to the NaCl; at temperature T1, it was noted that increased concentration from 0.25 M to 0.75 M significantly reduces the permeate flow. The reduction in permeate flow was nonlinear for a given pressure 30 kPa and velocity 5.22 m/s, but linear for all other variables. It was also observed that with an increase in temperature from 60 °C to 70 °C, the permeate flux for concentration 0.25 M was 49% for all the combinations of pressure and velocity. In addition, permeate flow increased 53% from temperature 50 °C to 60 °C and 49% from temperature 60 °C to 70 °C for both the solutions at a concentration of 0.25 M. This shows that the temperature also had a profound impact on the permeate flux. The economic analysis and market survey shows that the cost of clean water at the lab level was high which can be significantly reduced using a large-scale setup providing 1,000,000 L/H of distilled water. Full article

(This article belongs to the Special Issue Recent Studies of Membranes for Liquids Separation and Water Treatment)

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22 pages, 2982 KiB

Open AccessReview

Modified Electrospun Membranes Using Different Nanomaterials for Membrane Distillation

by Muzamil Khatri, Lijo Francis and Nidal Hilal

Membranes 2023, 13(3), 338; https://doi.org/10.3390/membranes13030338 - 14 Mar 2023

Cited by 16 | Viewed by 4908

Abstract

Obtaining fresh drinking water is a challenge directly related to the change in agricultural, industrial, and societal demands and pressure. Therefore, the sustainable treatment of saline water to get clean water is a major requirement for human survival. In this review, we have [...] Read more.

Obtaining fresh drinking water is a challenge directly related to the change in agricultural, industrial, and societal demands and pressure. Therefore, the sustainable treatment of saline water to get clean water is a major requirement for human survival. In this review, we have detailed the use of electrospun nanofiber-based membranes (ENMs) for water reclamation improvements with respect to physical and chemical modifications. Although membrane distillation (MD) has been considered a low-cost water reclamation process, especially with the availability of low-grade waste heat sources, significant improvements are still required in terms of preparing efficient membranes with enhanced water flux, anti-fouling, and anti-scaling characteristics. In particular, different types of nanomaterials have been explored as guest molecules for electrospinning with different polymers. Nanomaterials such as metallic organic frameworks (MOFs), zeolites, dioxides, carbon nanotubes (CNTs), etc., have opened unprecedented perspectives for the implementation of the MD process. The integration of nanofillers gives appropriate characteristics to the MD membranes by changing their chemical and physical properties, which significantly enhances energy efficiency without impacting the economic costs. Here, we provide a comprehensive overview of the state-of-the-art status, the opportunities, open challenges, and pitfalls of the emerging field of modified ENMs using different nanomaterials for desalination applications. Full article

(This article belongs to the Special Issue Surface Modification and Performance Enhancement in Membrane Separation Technologies)

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21 pages, 3922 KiB

Open AccessArticle

Polydimethylsiloxane/Magnesium Oxide Nanosheet Mixed Matrix Membrane for CO₂ Separation Application

by Muhd Izzudin Fikry Zainuddin, Abdul Latif Ahmad and Meor Muhammad Hafiz Shah Buddin

Membranes 2023, 13(3), 337; https://doi.org/10.3390/membranes13030337 - 14 Mar 2023

Cited by 8 | Viewed by 2660

Abstract

Carbon dioxide (CO₂) concentration is now 50% higher than in the preindustrial period and efforts to reduce CO₂ emission through carbon capture and utilization (CCU) are blooming. Membranes are one of the attractive alternatives for such application. In this study, [...] Read more.

Carbon dioxide (CO₂) concentration is now 50% higher than in the preindustrial period and efforts to reduce CO₂ emission through carbon capture and utilization (CCU) are blooming. Membranes are one of the attractive alternatives for such application. In this study, a rubbery polymer polydimethylsiloxane (PDMS) membrane is incorporated with magnesium oxide (MgO) with a hierarchically two-dimensional (2D) nanosheet shape for CO₂ separation. The average thickness of the synthesized MgO nanosheet in this study is 35.3 ± 1.5 nm. Based on the pure gas separation performance, the optimal loading obtained is at 1 wt.% where there is no observable significant agglomeration. CO₂ permeability was reduced from 2382 Barrer to 1929 Barrer while CO₂/N₂ selectivity increased from only 11.4 to 12.7, and CO₂/CH₄ remained relatively constant when the MMM was operated at 2 bar and 25 °C. Sedimentation of the filler was observed when the loading was further increased to 5 wt.%, forming interfacial defects on the bottom side of the membrane and causing increased CO₂ gas permeability from 1929 Barrer to 2104 Barrer as compared to filler loading at 1 wt.%, whereas the CO₂/N₂ ideal selectivity increased from 12.1 to 15.0. Additionally, this study shows that there was no significant impact of pressure on separation performance. There was a linear decline of CO₂ permeability with increasing upstream pressure while there were no changes to the CO₂/N₂ and CO₂/CH₄ selectivity. Full article

(This article belongs to the Special Issue Membrane Science towards Sustainable Development Goals (SDGs))

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14 pages, 4544 KiB

Open AccessArticle

Treatment of Semiconductor Wastewater Containing Tetramethylammonium Hydroxide (TMAH) Using Nanofiltration, Reverse Osmosis, and Membrane Capacitive Deionization

by Juyoung Lee, Song Lee, Yongjun Choi and Sangho Lee

Membranes 2023, 13(3), 336; https://doi.org/10.3390/membranes13030336 - 14 Mar 2023

Cited by 3 | Viewed by 4001

Abstract

As the semiconductor industry has grown tremendously over the last decades, its environmental impact has become a growing concern, including the withdrawal of fresh water and the generation of harmful wastewater. Tetramethylammonium hydroxide (TMAH), one of the toxic compounds inevitably found in semiconductor [...] Read more.

As the semiconductor industry has grown tremendously over the last decades, its environmental impact has become a growing concern, including the withdrawal of fresh water and the generation of harmful wastewater. Tetramethylammonium hydroxide (TMAH), one of the toxic compounds inevitably found in semiconductor wastewater, should be removed before the wastewater is discharged. However, there are few affordable technologies available to remove TMAH from semiconductor wastewater. Therefore, the objective of this study was to compare different treatment options, such as Membrane Capacitive Deionization (MCDI), Reverse Osmosis (RO), and Nanofiltration (NF), for the treatment of semiconductor wastewater containing TMAH. A series of bench-scale experimental setups were conducted to investigate the removal efficiencies of TMAH, TDS, and TOC. The results confirmed that the MCDI process showed its great ability as well as RO to remove them, while the NF could not make a sufficient removal under identical recovery conditions. MCDI showed higher removals of monovalent ions, including TMA+, than divalent ions. Moreover, the removal of TMA+ by MCDI was higher under the basic solution than under both neutral and acidic conditions. These results were the first to demonstrate that MCDI has significant potential for treating semiconductor wastewater that contains TMAH. Full article

(This article belongs to the Special Issue Selected Papers from the MELPRO 2022)

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