Membranes

12 pages, 6822 KiB

Open AccessArticle

In Situ-Grown Al₂O₃ Nanoflowers and Hydrophobic Modification Enable Superhydrophobic SiC Ceramic Membranes for Membrane Distillation

by Yuqi Song, Kai Miao, Jinxin Liu, Yutang Kang, Dong Zou and Zhaoxiang Zhong

Membranes 2024, 14(5), 117; https://doi.org/10.3390/membranes14050117 - 19 May 2024

Viewed by 1289

Abstract

Membrane distillation (MD) is considered a promising technology for desalination. In the MD process, membrane pores are easily contaminated and wetted, which will degrade the permeate flux and salt rejection of the membrane. In this work, SiC ceramic membranes were used as the [...] Read more.

Membrane distillation (MD) is considered a promising technology for desalination. In the MD process, membrane pores are easily contaminated and wetted, which will degrade the permeate flux and salt rejection of the membrane. In this work, SiC ceramic membranes were used as the supports, and an Al₂O₃ micro-nano structure was constructed on its surface. The surface energy of Al₂O₃@SiC micro-nano composite membranes was reduced by organosilane grafting modification. The effective deposition of Al₂O₃ nanoflowers on the membrane surface increased membrane roughness and enhanced the anti-fouling and anti-wetting properties of the membranes. Simultaneously, the presence of nanoflowers also regulated the pore structures and thus decreased the membrane pore size. In addition, the effects of Al₂(SO₄)₃ concentration and sintering temperature on the surface morphology and performance of the membranes were investigated in detail. It was demonstrated that the water contact angle of the resulting membrane was 152.4°, which was higher than that of the pristine membrane (138.8°). In the treatment of saline water containing 35 g/L of NaCl, the permeate flux was about 11.1 kg⋅m⁻²⋅h⁻¹ and the salt rejection was above 99.9%. Note that the pristine ceramic membrane cannot be employed for MD due to its larger membrane pore size. This work provides a new method for preparing superhydrophobic ceramic membranes for MD. Full article

(This article belongs to the Special Issue Advances in Porous Hydrophobic Membrane Materials for Membrane Distillation)

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22 pages, 5370 KiB

Open AccessArticle

Enhancing Water Purification by Integrating Titanium Dioxide Nanotubes into Polyethersulfone Membranes for Improved Hydrophilicity and Anti-Fouling Performance

by Ayesha Bilal, Muhammad Yasin, Faheem Hassan Akhtar, Mazhar Amjad Gilani, Hamad Almohamadi, Mohammad Younas, Azeem Mushtaq, Muhammad Aslam, Mehdi Hassan, Rab Nawaz, Aqsha Aqsha, Jaka Sunarso, Muhammad Roil Bilad and Asim Laeeq Khan

Membranes 2024, 14(5), 116; https://doi.org/10.3390/membranes14050116 - 17 May 2024

Cited by 4 | Viewed by 1742

Abstract

Water pollution remains a critical concern, one necessitated by rapidly increasing industrialization and urbanization. Among the various strategies for water purification, membrane technology stands out, with polyethersulfone (PES) often being the material of choice due to its robust mechanical properties, thermal stability, and [...] Read more.

Water pollution remains a critical concern, one necessitated by rapidly increasing industrialization and urbanization. Among the various strategies for water purification, membrane technology stands out, with polyethersulfone (PES) often being the material of choice due to its robust mechanical properties, thermal stability, and chemical resistance. However, PES-based membranes tend to exhibit low hydrophilicity, leading to reduced flux and poor anti-fouling performance. This study addresses these limitations by incorporating titanium dioxide nanotubes (TiO₂NTs) into PES nanofiltration membranes to enhance their hydrophilic properties. The TiO₂NTs, characterized through FTIR, XRD, BET, and SEM, were embedded in PES at varying concentrations using a non-solvent induced phase inversion (NIPS) method. The fabricated mixed matrix membranes (MMMs) were subjected to testing for water permeability and solute rejection capabilities. Remarkably, membranes with a 1 wt% TiO₂NT loading displayed a significant increase in pure water flux, from 36 to 72 L m² h⁻¹ bar⁻¹, a 300-fold increase in selectivity compared to the pristine sample, and a dye rejection of 99%. Furthermore, long-term stability tests showed only a slight reduction in permeate flux over a time of 36 h, while dye removal efficiency was maintained, thus confirming the membrane’s stability. Anti-fouling tests revealed a 93% flux recovery ratio, indicating excellent resistance to fouling. These results suggest that the inclusion of TiO₂ NTs offers a promising avenue for the development of efficient and stable anti-fouling PES-based membranes for water purification. Full article

(This article belongs to the Special Issue Membrane-Based Technologies for Water/Wastewater Treatment)

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11 pages, 1494 KiB

Open AccessArticle

Revamping of a Full-Scale Membrane Plant for Landfill Leachate Pretreatment Using Partial Nitritation

by Laura Palli, Francesca Tuci, Letizia Macellaro La Franca, Donatella Fibbi and Riccardo Gori

Membranes 2024, 14(5), 115; https://doi.org/10.3390/membranes14050115 - 14 May 2024

Cited by 1 | Viewed by 963

Abstract

This paper describes a case study involving a revamping of a full-scale membrane bioreactor that treats landfill leachate and other liquid wastes. The main change was the introduction of nitritation/denitritation in alternating cycles instead of the classic denitrification/nitrification process, together with the installation [...] Read more.

This paper describes a case study involving a revamping of a full-scale membrane bioreactor that treats landfill leachate and other liquid wastes. The main change was the introduction of nitritation/denitritation in alternating cycles instead of the classic denitrification/nitrification process, together with the installation of fine bubble diffusers, a reduction in the volume of the biological compartment, and an increase in the equalization volume. The most significant results were obtained for the biological compartment, with a decrease in the specific energy consumption of 46.6%. At the same time, the removal efficiency of COD, BOD, and TN substantially remained the same before and after plant revamping, while the removal efficiency of TP increased over the years, reaching an average value of almost 71%. Regarding the ultrafiltration unit, the specific flux (or permeability) was characterized by an increasing trend. At the same time, the specific energy consumption of this section decreased by 9.4%. These results led to the conclusion that the changes introduced with the revamp led to a more stable process, a reduction in membrane fouling, and important energy savings. Full article

(This article belongs to the Special Issue A Commemorative Special Issue in Honor of Professor Simon Judd)

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12 pages, 3746 KiB

Open AccessArticle

The Helix Ring Peptide U₁₁ from the Venom of the Ant, Tetramorium bicarinatum, Acts as a Putative Pore-Forming Toxin

by Steve Peigneur, Diogo Tibery and Jan Tytgat

Membranes 2024, 14(5), 114; https://doi.org/10.3390/membranes14050114 - 14 May 2024

Viewed by 1131

Abstract

An insect neuroactive helix ring peptide called U₁₁-MYRTX-Tb1a (abbreviated as U₁₁) from the venom of the ant, Tetramorium bicarinatum. U₁₁ is a 34-amino-acid peptide that is claimed to be one of the most paralytic peptides ever reported [...] Read more.

An insect neuroactive helix ring peptide called U₁₁-MYRTX-Tb1a (abbreviated as U₁₁) from the venom of the ant, Tetramorium bicarinatum. U₁₁ is a 34-amino-acid peptide that is claimed to be one of the most paralytic peptides ever reported from ant venoms acting against blowflies and honeybees. The peptide features a compact triangular ring helix structure stabilized by a single disulfide bond, which is a unique three-dimensional scaffold among animal venoms. Pharmacological assays using Drosophila S2 cells have demonstrated that U₁₁ is not cytotoxic but instead suggest that it may modulate potassium channels via the presence of a functional dyad. In our work described here, we have tested this hypothesis by investigating the action of synthetically made U₁₁ on a wide array of voltage-gated K and Na channels since it is well known that these channels play a crucial role in the phenomenon of paralysis. Using the Xenopus laevis oocyte heterologous expression system and voltage clamp, our results have not shown any modulatory effect of 1 μM U₁₁ on the activity of Kv1.1, Kv1.3, Kv1.4, Kv1.5, Shaker IR, Kv4.2, Kv7.1, Kv10.1, Kv11.1 and KQT1, nor on DmNav and BgNav. Instead, 10 μM U₁₁ caused a quick and irreversible cytolytic effect, identical to the cytotoxic effect caused by Apis mellifera venom, which indicates that U₁₁ can act as a pore-forming peptide. Interestingly, the paralytic dose (PD₅₀) on blowflies and honeybees corresponds with the concentration at which U₁₁ displays clear pore-forming activity. In conclusion, our results indicate that the insecticidal and paralytic effects caused by U₁₁ may be explained by the putative pore formation of the peptide. Full article

(This article belongs to the Collection Feature Papers in Biological Membrane Functions)

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11 pages, 909 KiB

Open AccessArticle

Can Storage Stability and Simulated Gastrointestinal Behavior Change the Cytotoxic Effects of Concentrated Guava Leaves Extract against Human Lung Cancer Cells?

by Giordana Demaman Arend, Silvani Verruck, Naira Fernanda Zanchett Schneider, Cláudia Maria Oliveira Simões, Marcus Vinícius Tres, Elane Schwinden Prudêncio, José Carlos Cunha Petrus and Katia Rezzadori

Membranes 2024, 14(5), 113; https://doi.org/10.3390/membranes14050113 - 14 May 2024

Viewed by 908

Abstract

The influence of storage stability and simulated gastrointestinal behavior of different extracts of guava leaves extracts (NC: not concentrated, and C10 and C20: concentrated by nanofiltration) was evaluated based on their total phenolic compound (TPC) contents and antioxidant activity as well as on [...] Read more.

The influence of storage stability and simulated gastrointestinal behavior of different extracts of guava leaves extracts (NC: not concentrated, and C10 and C20: concentrated by nanofiltration) was evaluated based on their total phenolic compound (TPC) contents and antioxidant activity as well as on their cytotoxic effects on A549 and Vero cells. The results showed that C10 and C20 presented high stability for 125 days probably due to their high TPC contents and antioxidant activity. The simulated gastrointestinal behavior modified their TPC contents; however, after all digestion steps, the TPC values were higher than 70%, which means that they were still available to exert their bioactivities. Additionally, the cytotoxic effects of these extracts were evaluated before and after the simulated gastrointestinal behavior or under different storage conditions. C10 presented the best selectivity indices (SI) values (IC50 Vero cells/IC50 A549 cells) at both conditions suggesting that it can be considered a potential extract to be developed as a functional food due to its resistance to the gastrointestinal digestion and storage conditions tested. Full article

(This article belongs to the Special Issue Innovations in Membrane Technology for Food Applications)

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16 pages, 4112 KiB

Open AccessArticle

Mo-BiVO₄ Photocatalytically Modified Ceramic Ultrafiltration Membranes for Enhanced Water Treatment Efficiency

by George V. Theodorakopoulos, Martha Pylarinou, Elias Sakellis, Fotios K. Katsaros, Vlassis Likodimos and George Em. Romanos

Membranes 2024, 14(5), 112; https://doi.org/10.3390/membranes14050112 - 14 May 2024

Viewed by 934

Abstract

This study highlights the effectiveness of photocatalytically modified ceramic ultrafiltration (UF) membranes in alleviating two major drawbacks of membrane filtration technologies. These are the generation of a highly concentrated retentate effluent as a waste stream and the gradual degradation of the water flux [...] Read more.

This study highlights the effectiveness of photocatalytically modified ceramic ultrafiltration (UF) membranes in alleviating two major drawbacks of membrane filtration technologies. These are the generation of a highly concentrated retentate effluent as a waste stream and the gradual degradation of the water flux through the membrane due to the accumulation of organic pollutants on its surface. The development of two types of novel tubular membranes, featuring photocatalytic Mo-BiVO₄ inverse opal coatings, demonstrated a negligible impact on water permeance, ensuring consistent filtration and photocatalytic efficiency and suggesting the potential for maintaining membrane integrity and avoiding the formation of highly concentrated retentate effluents. Morphological analysis revealed well-defined coatings with ordered domains and interconnected macropores, confirming successful synthesis of Mo-BiVO₄. Raman spectroscopy and optical studies further elucidated the composition and light absorption properties of the coatings, particularly within the visible region, which is vital for photocatalysis driven by vis-light. Evaluation of the tetracycline removal efficiency presented efficient adsorption onto membrane surfaces with enhanced photocatalytic activity observed under both UV and vis-light. Additionally, vis-light irradiation facilitated significant degradation, showcasing the versatility of the membranes. Total Organic Carbon (TOC) analysis corroborated complete solute elimination or photocatalytic degradation without the production of intermediates, highlighting the potential for complete pollutant removal. Overall, these findings emphasize the promising applications of Mo-BiVO₄ photocatalytic membranes in sustainable water treatment and wastewater remediation processes, laying the groundwork for further optimization and scalability in practical water treatment systems. Full article

(This article belongs to the Section Membrane Applications for Water Treatment)

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22 pages, 2866 KiB

Open AccessArticle

Targeted Anthocyanin Enrichment of Cranberry Juice by Electrodialysis with Filtration Membranes: Impact of Filtration Membrane Physicochemical Properties and Predictive Statistical Models

by Eva Revellat and Laurent Bazinet

Membranes 2024, 14(5), 111; https://doi.org/10.3390/membranes14050111 - 14 May 2024

Cited by 1 | Viewed by 1105

Abstract

To optimize cranberry juice enrichment, correlation between physicochemical properties of filtration membranes (FM) and anthocyanin migration was investigated during electrodialysis with filtration membranes (EDFM) using redundancy (RDA) and multivariate regression (MRGA) analyses. Six polyether sulfone (PES) and polyvinylidene fluoride (PVDF) membranes with molecular [...] Read more.

To optimize cranberry juice enrichment, correlation between physicochemical properties of filtration membranes (FM) and anthocyanin migration was investigated during electrodialysis with filtration membranes (EDFM) using redundancy (RDA) and multivariate regression (MRGA) analyses. Six polyether sulfone (PES) and polyvinylidene fluoride (PVDF) membranes with molecular weight cut-offs between 150 and 500 kDa, commercially available at large scale, were characterized in terms of nine physicochemical characteristics and used for EDFM. The highest migration of total anthocyanin was obtained with PVDF 250 kDa, with a global migration rate of 3.5 ± 0.4 g/m²·h. RDA showed that two FM properties (mesopore porosity and hydrophilic porosity) were significantly negatively correlated to the anthocyanin’s migration and explained 67.4% of their total variation in migration. Predictive MRGA models were also developed for each anthocyanin based on these significant FM properties. A combination of intermolecular interactions may lead to binding in a cooperative and synergistic mode and hinder the anthocyanin migration. Full article

(This article belongs to the Special Issue Research on Electrodialytic Processes)

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13 pages, 2016 KiB

Open AccessArticle

Towards the Optimization of a Photovoltaic/Membrane Distillation System for the Production of Pure Water

by Dufei Fang, Damian M. Amiruddin, Imin Kao, Devinder Mahajan, Xuming Chen and Benjamin S. Hsiao

Membranes 2024, 14(5), 110; https://doi.org/10.3390/membranes14050110 - 13 May 2024

Viewed by 1315

Abstract

The production of pure water plays a pivotal role in enabling sustainable green hydrogen production through electrolysis. The current industrial approach for generating pure water relies on energy-intensive techniques such as reverse osmosis. This study unveils a straightforward method to produce pure water, [...] Read more.

The production of pure water plays a pivotal role in enabling sustainable green hydrogen production through electrolysis. The current industrial approach for generating pure water relies on energy-intensive techniques such as reverse osmosis. This study unveils a straightforward method to produce pure water, employing real-world units derived from previously simulated and developed laboratory devices. This demonstrated system is cost-effective and boasts low energy consumption, utilizing membrane distillation (MD) driven by the waste heat harnessed from photovoltaic (PV) panels. In a previous study, modeling simulations were conducted to optimize the multi-layered MD system, serving as a blueprint for the construction of prototype devices with a suitable selection of materials, enabling the construction of field-testable units. The most efficient PV-MD device, featuring evaporation and condensation zones constructed from steel sheets and polytetrafluoroethylene (PTFE) membranes, is capable of yielding high-purity water with conductivity levels below 145 μS with high flux rates. Full article

(This article belongs to the Collection Feature Papers in Membrane Engineering and Applications)

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18 pages, 1347 KiB

Open AccessReview

Impact of Nitrate on the Removal of Pollutants from Water in Reducing Gas-Based Membrane Biofilm Reactors: A Review

by Zhiheng Zhang, Zhian Huang, Haixiang Li, Dunqiu Wang, Yi Yao and Kun Dong

Membranes 2024, 14(5), 109; https://doi.org/10.3390/membranes14050109 - 9 May 2024

Viewed by 1552

Abstract

The membrane biofilm reactor (MBfR) is a novel wastewater treatment technology, garnering attention due to its high gas utilization rate and effective pollutant removal capability. This paper outlines the working mechanism, advantages, and disadvantages of MBfR, and the denitrification pathways, assessing the efficacy [...] Read more.

The membrane biofilm reactor (MBfR) is a novel wastewater treatment technology, garnering attention due to its high gas utilization rate and effective pollutant removal capability. This paper outlines the working mechanism, advantages, and disadvantages of MBfR, and the denitrification pathways, assessing the efficacy of MBfR in removing oxidized pollutants (sulfate (SO₄⁻), perchlorate (ClO₄⁻)), heavy metal ions (chromates (Cr(VI)), selenates (Se(VI))), and organic pollutants (tetracycline (TC), p-chloronitrobenzene (p-CNB)), and delves into the role of related microorganisms. Specifically, through the addition of nitrates (NO₃⁻), this paper analyzes its impact on the removal efficiency of other pollutants and explores the changes in microbial communities. The results of the study show that NO³⁻ inhibits the removal of other pollutants (oxidizing pollutants, heavy metal ions and organic pollutants), etc., in the simultaneous removal of multiple pollutants by MBfR. Full article

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16 pages, 5673 KiB

Open AccessArticle

Multifunctional Eco-Friendly Adsorbent Cryogels Based on Xylan Derived from Coffee Residues

by Valentina Quintero, Johann F. Osma, Ulugbek Azimov and Debora Nabarlatz

Membranes 2024, 14(5), 108; https://doi.org/10.3390/membranes14050108 - 8 May 2024

Viewed by 1425

Abstract

Agricultural and animal farming practices contribute significantly to greenhouse gas (GHG) emissions such as NH₃, CH₄, CO₂, and NO_x, causing local environmental concerns involving health risks and water/air pollution. A growing need to capture these [...] Read more.

Agricultural and animal farming practices contribute significantly to greenhouse gas (GHG) emissions such as NH₃, CH₄, CO₂, and NO_x, causing local environmental concerns involving health risks and water/air pollution. A growing need to capture these pollutants is leading to the development of new strategies, including the use of solid adsorbents. However, commonly used adsorbent materials often pose toxicity and negative long-term environmental effects. This study aimed to develop responsive eco-friendly cryogels using xylan extracted from coffee parchment, a typical residue from coffee production. The crosslinking in cryogels was accomplished by “freeze-thawing” and subsequent freeze-drying. Cryogels were characterized in terms of morphology by using scanning electron microscopy, porosity, and density by the liquid saturation method and also moisture adsorption and ammonia adsorption capacity. The analysis showed that the porosity in the cryogels remained around 0.62–0.42, while the apparent densities varied from 0.14 g/cm³ to 0.25 g/cm³. The moisture adsorption capacity was the highest at the highest relative humidity level (80%), reaching 0.25–0.43 g of water per gram of sample; the amount of water adsorbed increased when the xylan content in the cryogel increased up to 10% w/v, which was consistent with the hygroscopic nature of xylan. The ammonia adsorption process was modeled accurately by a pseudo-second-order equation, where the maximum adsorption capacity in equilibrium reached 0.047 mg NH₃/g when xylan reached 10% w/v in cryogels, indicating a chemisorption process. The cryogels under investigation hold promise for ammonia adsorption applications and GHG separation, offering a sustainable alternative for gas-capturing processes. Full article

(This article belongs to the Section Membrane Applications)

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19 pages, 3832 KiB

Open AccessArticle

Technical Feasibility of Extraction of Freshwater from Produced Water with Combined Forward Osmosis and Nanofiltration

by Madina Mohamed, Marco Tagliabue and Alberto Tiraferri

Membranes 2024, 14(5), 107; https://doi.org/10.3390/membranes14050107 - 3 May 2024

Viewed by 1266

Abstract

This study assesses the technical feasibility of a forward-osmosis-based system for concentrating produced water and extracting freshwater. Forward osmosis was combined with nanofiltration, the latter system used to restore the initial osmotic pressure of the diluted draw solutions while concurrently obtaining the final [...] Read more.

This study assesses the technical feasibility of a forward-osmosis-based system for concentrating produced water and extracting freshwater. Forward osmosis was combined with nanofiltration, the latter system used to restore the initial osmotic pressure of the diluted draw solutions while concurrently obtaining the final freshwater product. Three draw solutions, namely, MgCl₂, NaCl, and C₃H₅NaO₂, were initially tested against a synthetic water mimicking a pretreated produced water effluent having an osmotic pressure equal to 16.3 bar. MgCl₂ was thus selected for high-recovery experiments. Different combinations of draw solution osmotic pressure (30, 40, 60, 80, and 120) and draw-to-feed initial volume ratios (1, 1.6, and 2.2) were tested at the laboratory scale, achieving recovery rates between roughly 35% and 70% and water fluxes between 4 and 8 L m⁻²h⁻¹. One-dimensional, system-wide simulations deploying the analytical FO water flux equation were utilized to validate the experiments, investigate co-current and counter-current configurations, and understand the system potential. The diluted draw solutions were then transferred to nanofiltration to regenerate their original osmotic pressure. There, the highest observed rejection was 96.6% with an average flux of 21 L m⁻²h⁻¹, when running the system to achieve 100% relative recovery. Full article

(This article belongs to the Topic Membrane Separation Technology Research)

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18 pages, 17272 KiB

Open AccessArticle

Green and Sustainable Forward Osmosis Process for the Concentration of Apple Juice Using Sodium Lactate as Draw Solution

by Yuhang Zhao, Chang Liu, Jianju Deng, Panpan Zhang, Shiyuan Feng and Yu Chen

Membranes 2024, 14(5), 106; https://doi.org/10.3390/membranes14050106 - 2 May 2024

Cited by 1 | Viewed by 1587

Abstract

China is the world’s largest producer and exporter of concentrated apple juice (CAJ). However, traditional concentration methods such as vacuum evaporation (VE) and freeze concentration cause the loss of essential nutrients and heat-sensitive components with high energy consumption. A green and effective technique [...] Read more.

China is the world’s largest producer and exporter of concentrated apple juice (CAJ). However, traditional concentration methods such as vacuum evaporation (VE) and freeze concentration cause the loss of essential nutrients and heat-sensitive components with high energy consumption. A green and effective technique is thus desired for juice concentration to improve product quality and sustainability. In this study, a hybrid forward osmosis–membrane distillation (FO–MD) process was explored for the concentration of apple juice using sodium lactate (L-NaLa) as a renewable draw solute. As a result, commercial apple juice could be concentrated up to 65 °Brix by the FO process with an average flux of 2.5 L·m⁻²·h⁻¹. Most of the nutritional and volatile compounds were well retained in this process, while a significant deterioration in product quality was observed in products obtained by VE concentration. It was also found that membrane fouling in the FO concentration process was reversible, and a periodical UP water flush could remove most of the contaminants on the membrane surface to achieve a flux restoration of more than 95%. In addition, the L-NaLa draw solution could be regenerated by a vacuum membrane distillation (VMD) process with an average flux of around 7.87 L∙m⁻²∙h⁻¹ for multiple reuse, which further enhanced the long-term sustainability of the hybrid process. Full article

(This article belongs to the Special Issue Membranes for Food Preservation and Processing)

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14 pages, 1172 KiB

Open AccessArticle

Phospholipid Membrane Interactions of Model Ac-WL-X-LL-OH Peptides Investigated by Solid-State Nuclear Magnetic Resonance

by Nicolai Etwin Alsaker, Øyvind Halskau, Bengt Erik Haug, Nathalie Reuter and Willy Nerdal

Membranes 2024, 14(5), 105; https://doi.org/10.3390/membranes14050105 - 1 May 2024

Cited by 1 | Viewed by 1521

Abstract

The role of aromatic amino acids in peripheral protein membrane binding has been reported to involve cation–π interactions with choline lipids. In this study, we have investigated the interactions of the model pentapeptide Ac-WL-X-LL-OH (where X = L, Y, F, or W) with [...] Read more.

The role of aromatic amino acids in peripheral protein membrane binding has been reported to involve cation–π interactions with choline lipids. In this study, we have investigated the interactions of the model pentapeptide Ac-WL-X-LL-OH (where X = L, Y, F, or W) with the phospholipid membrane using solid-state NMR. The effect of guest residue X on the peptide-lipid interactome was complementary to the seminal report on the interfacial hydrophobicity scale by Wimley and White. We found that the phospholipids retained a lamellar phase in the presence of each of the peptides with an aromatic X residue, whereas the Leu peptide perturbed the bilayer to an extent where an additional isotropic phase was observed. The solid-state NMR ¹³C and ³¹P data provide additional information on the influence of these short peptides on the membrane that has not been previously reported. The magnitude of membrane perturbation was in the order of guest residue X = L > Y~F > W, which is consistent with the relative amino acid interfacial affinity reported by Wimley and White. Further work is, however, required to uncover the behavior of the peptide and localization in the membrane domain due to ambiguity of the ¹³C NMR data. We have launched efforts in this regard for the objective of better understanding the role of aromatic amino acids in peripheral membrane protein binding. Full article

(This article belongs to the Special Issue Protein–Lipid Interactions: Recent Studies, Perspectives, and Challenges)

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19 pages, 2861 KiB

Open AccessArticle

Effect of Soybean Oil on the Improvement of the Functionality of Edible Membrane-Type Food Packaging Films Based on Caseinate–Carboxymethyl Chitosan Compositions

by Amal M. A. Mohamed and Hosahalli S. Ramaswamy

Membranes 2024, 14(5), 104; https://doi.org/10.3390/membranes14050104 - 30 Apr 2024

Cited by 1 | Viewed by 1205

Abstract

Edible film biopolymers are gaining attention to tackle problems of plastic waste and food safety to alleviate environmental problems associated with plastic products in food packaging. In this study, caseinate–carboxymethyl chitosan (CA–CMCH) composite films were made with the incorporation of soybean oil (SO) [...] Read more.

Edible film biopolymers are gaining attention to tackle problems of plastic waste and food safety to alleviate environmental problems associated with plastic products in food packaging. In this study, caseinate–carboxymethyl chitosan (CA–CMCH) composite films were made with the incorporation of soybean oil (SO) using a casting technique. The influence of different soybean oil concentrations at 0, 0.5, and 1% (w/w) on physical, mechanical, barrier, and surface characteristics of films composed of caseinate–carboxymethyl chitosan (CA–CMCH) was evaluated. The brightest film (L* value of 95.95 ± 0.30) was obtained with the edible film made from the control group of samples with sodium caseinate (NaCA-100; 100% NaCA). The results also indicated that samples with 1% SO in NaCA-75 and CaCA-75 had lower water vapor permeability (WVP), while those with NaCA-50 and CaCA-50 showed higher values of WVP. For mechanical properties, this study found that incorporating soybean oil into the caseinate–carboxymethyl (CA–CMCH) composite films led to an enhancement of both tensile strength and elongation at break. The morphological structures, determined using SEM, of control and composite films showed compact and homogenous surfaces. Overall, the addition of soybean oil contributed to the improvement of the functional properties of the edible films, offering potential solutions to the environmental issues associated with plastic packaging and enhancing the safety and performance of food packaging. Full article

(This article belongs to the Section Membrane Applications)

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20 pages, 4841 KiB

Open AccessArticle

Applying Nanofiltration to Decrease Energy Consumption and Sensitivity toward Feed Composition Fluctuations in Salt Production

by Marian Turek, Krzysztof Mitko and Paweł Skóra

Membranes 2024, 14(5), 103; https://doi.org/10.3390/membranes14050103 - 29 Apr 2024

Viewed by 1337

Abstract

The only currently active industrial-scale plant that uses coal mine brines, located in Czerwionka-Leszczyny, uses ZOD (Zakład Odsalania Dębieńsko, the name of the plant’s former owner) technology, based on mechanical vapor compression evaporators. The plant produces evaporated salt that meets the specifications for [...] Read more.

The only currently active industrial-scale plant that uses coal mine brines, located in Czerwionka-Leszczyny, uses ZOD (Zakład Odsalania Dębieńsko, the name of the plant’s former owner) technology, based on mechanical vapor compression evaporators. The plant produces evaporated salt that meets the specifications for edible salt; however, the technology is highly energy-consuming. The presented work focuses on the modeling of ZOD technology if applied to the water treatment of the ‘Ziemowit-650’ coal mine. Using the results of bench-scale investigation of brine nanofiltration and a mathematical model of ZOD technology based on Czerwionka-Leszczyny performance, the energy consumption per ton of produced salt was estimated for two cases: (1) ZOD technology treating the ‘Ziemowit-650’ brine and (2) ZOD technology treating the permeate of nanofiltration (NF) working on the ‘Ziemowit-650’ brine. The sensitivity of the system was investigated in the range of −10% to + 10% of Cl⁻, SO₄²⁻, Mg²⁺, and Ca²⁺ concentration, assuming that the sodium concentration also changes to meet the electroneutrality requirement. The results show that nanofiltration pretreatment not only decreases energy consumption but it also makes salt production less sensitive to fluctuations in feed water composition. Full article

(This article belongs to the Special Issue Design and Optimisation of Membrane Technologies for Wastewater Treatment)

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18 pages, 1063 KiB

Open AccessArticle

Transmembrane Chemical Absorption Process for Recovering Ammonia as an Organic Fertilizer Using Citric Acid as the Trapping Solution

by Ricardo Reyes Alva, Marius Mohr and Susanne Zibek

Membranes 2024, 14(5), 102; https://doi.org/10.3390/membranes14050102 - 29 Apr 2024

Viewed by 1463

Abstract

Membrane contactors are among the available technologies that allow a reduction in the amount of ammoniacal nitrogen released into the environment through a process called transmembrane chemical absorption (TMCA). This process can be operated with different substances acting as trapping solutions; however, strong [...] Read more.

Membrane contactors are among the available technologies that allow a reduction in the amount of ammoniacal nitrogen released into the environment through a process called transmembrane chemical absorption (TMCA). This process can be operated with different substances acting as trapping solutions; however, strong inorganic acids have been studied the most. The purpose of this study was to demonstrate, at laboratory scale, the performance of citric acid as a capturing solution in TMCA processes for recovering ammonia as an organic fertilizer from anaerobic digestor reject water using membrane contactors in a liquid–liquid configuration and to compare it with the most studied solution, sulfuric acid. The experiments were carried out at 22 °C and 40 °C and with a feed water pH of 10 and 10.5. When the system was operated at pH 10, the rates of recovered ammonia from the feed solution obtained with citric acid were 10.7–16.5 percentage points (pp) lower compared to sulfuric acid, and at pH 10.5, the difference decreased to 5–10 pp. Under all tested conditions, the water vapor transport in the system was lower when using citric acid as the trapping solution, and at pH 10 and 40 °C, it was 5.7 times lower. When estimating the operational costs for scaling up the system, citric acid appears to be a better option than sulfuric acid as a trapping solution, but in both cases, the process was not profitable under the studied conditions. Full article

(This article belongs to the Topic Technologies for Wastewater and Sludge Treatment)

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3 pages, 959 KiB

Open AccessCorrection

Correction: Dobrovskiy et al. The Transport Properties of Semi-Crystalline Polyetherimide BPDA-P3 in Amorphous and Ordered States: Computer Simulations. Membranes 2022, 12, 856

by Alexey Y. Dobrovskiy, Victor M. Nazarychev, Igor V. Volgin and Sergey V. Lyulin

Membranes 2024, 14(5), 101; https://doi.org/10.3390/membranes14050101 - 29 Apr 2024

Viewed by 813

Abstract

The authors wish to make a change to the published paper [...] Full article

(This article belongs to the Section Membrane Physics and Theory)

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10 pages, 1736 KiB

Open AccessEditorial

Editorial for the Special Issue “Preparation and Application of Advanced Functional Membranes”

by Annarosa Gugliuzza and Cristiana Boi

Membranes 2024, 14(5), 100; https://doi.org/10.3390/membranes14050100 - 26 Apr 2024

Viewed by 1292

Abstract

Membrane science is a discipline that cuts across almost all fields of research and experimentation [...] Full article

(This article belongs to the Special Issue Preparation and Application of Advanced Functional Membranes)

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18 pages, 3171 KiB

Open AccessEditor’s ChoiceReview

A Short Review of Advances in MOF Glass Membranes for Gas Adsorption and Separation

by Zichen Li, Yumei Wang, Jianxin Zhang, Shiqi Cheng and Yue Sun

Membranes 2024, 14(5), 99; https://doi.org/10.3390/membranes14050099 - 25 Apr 2024

Cited by 2 | Viewed by 2833

Abstract

The phenomenon of melting in metal–organic frameworks (MOFs) has recently garnered attention. Crystalline MOF materials can be transformed into an amorphous glassy state through melt-quenching treatment. The resulting MOF glass structure eliminates grain boundaries and retains short-range order while exhibiting long-range disorder. Based [...] Read more.

The phenomenon of melting in metal–organic frameworks (MOFs) has recently garnered attention. Crystalline MOF materials can be transformed into an amorphous glassy state through melt-quenching treatment. The resulting MOF glass structure eliminates grain boundaries and retains short-range order while exhibiting long-range disorder. Based on these properties, it emerges as a promising candidate for high-performance separation membranes. MOF glass membranes exhibit permanent and accessible porosity, allowing for selective adsorption of different gas species. This review summarizes the melting mechanism of MOFs and explores the impact of ligands and metal ions on glassy MOFs. Additionally, it presents an analysis of the diverse classes of MOF glass composites, outlining their structures and properties, which are conducive to gas adsorption and separation. The absence of inter-crystalline defects in the structures, coupled with their distinctive mechanical properties, renders them highly promising for industrial gas separation applications. Furthermore, this review provides a summary of recent research on MOF glass composite membranes for gas adsorption and separation. It also addresses the challenges associated with membrane production and suggests future research directions. Full article

(This article belongs to the Special Issue Recent Advances of Metal–Organic Framework Membranes for Separation Process)

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21 pages, 9185 KiB

Open AccessArticle

Enhancing the Permeate Flux Improvement of Direct Contact Membrane Distillation Modules with Inserted S-Ribs Carbon-Fiber Filaments

by Chii-Dong Ho, Yi-Wun Wang, Yi Chao, Thiam Leng Chew, Ming-Shen Jiang, Jian-Har Chen and Ching-Yu Li

Membranes 2024, 14(5), 98; https://doi.org/10.3390/membranes14050098 - 25 Apr 2024

Viewed by 1309

Abstract

Three widths of manufacturing S-ribs carbon-fiber filaments acting as turbulence promoters were implemented into the flow channel of direct contact membrane distillation (DCMD) modules to augment the permeate flux improvement in the present study. Attempts to reduce the disadvantageous temperature polarization effect were [...] Read more.

Three widths of manufacturing S-ribs carbon-fiber filaments acting as turbulence promoters were implemented into the flow channel of direct contact membrane distillation (DCMD) modules to augment the permeate flux improvement in the present study. Attempts to reduce the disadvantageous temperature polarization effect were made by inserting S-ribs turbulence promoters in improving pure water productivity, in which both heat- and mass-transfer boundary layers were diminished due to creating vortices in the flow pattern and increasing turbulence intensity. The temperature polarization coefficient

t_{t e m p}

was studied and found to enhance device performance (less thermal resistance) under inserting various S-ribs carbon-fiber thicknesses and operating both cocurrent- and countercurrent-flow patterns. The permeate fluxes in the DCMD modules with inserted S-ribs carbon-fiber turbulence promoters were investigated theoretically by developing the mathematical modeling equations and were conducted experimentally with various design and operating parameters. The theoretical predictions and experimental results exhibited a great potential to considerably achieve permeate flux enhancement in the new design of the DCMD system. The DCMD module with inserted S-ribs carbon-fiber turbulence promoters in the flow channel could provide a relative permeate flux enhancement up to 37.77% under countercurrent-flow operations in comparisons with the module of using the empty channel. An economic consideration on both permeate flux enhancement and power consumption increment for the module with inserted S-ribs carbon-fiber filaments was also delineated. Full article

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17 pages, 13980 KiB

Open AccessArticle

Enrichment of Nutmeg Essential Oil from Oil-in-Water Emulsions with PAN-Based Membranes

by Huilan Yin, Haoyu Zhang, Jiaoyang Cui, Qianlian Wu, Linlin Huang, Jiaoyue Qiu, Xin Zhang, Yanyu Xiang, Bo Li, Hongbo Liu, Zhishu Tang, Yue Zhang and Huaxu Zhu

Membranes 2024, 14(5), 97; https://doi.org/10.3390/membranes14050097 - 25 Apr 2024

Viewed by 1218

Abstract

This study used polyacrylonitrile (PAN) and heat-treated polyacrylonitrile (H-PAN) membranes to enrich nutmeg essential oils, which have more complex compositions compared with common oils. The oil rejection rate of the H-PAN membrane was higher than that of the PAN membrane for different oil [...] Read more.

This study used polyacrylonitrile (PAN) and heat-treated polyacrylonitrile (H-PAN) membranes to enrich nutmeg essential oils, which have more complex compositions compared with common oils. The oil rejection rate of the H-PAN membrane was higher than that of the PAN membrane for different oil concentrations of nutmeg essential oil-in-water emulsions. After heat treatment, the H-PAN membrane showed a smaller pore size, narrower pore size distribution, a rougher surface, higher hydrophilicity, and higher oleophobicity. According to the GC-MS results, the similarities of the essential oils enriched by the PAN and H-PAN membranes to those obtained by steam distillation (SD) were 0.988 and 0.990, respectively. In addition, these two membranes also exhibited higher essential oil rejection for Bupleuri Radix, Magnolia Officinalis Cortex, Caryophylli Flos, and Cinnamomi Cortex essential oil-in-water emulsions. This work could provide a reference for membrane technology for the non-destructive separation of oil with complex components from oil-in-water emulsions. Full article

(This article belongs to the Special Issue Application of Membrane Technology in Foods and Natural Products)

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24 pages, 3356 KiB

Open AccessOpinion

Membrane Heteroreceptor Complexes as Second-Order Protein Modulators: A Novel Integrative Mechanism through Allosteric Receptor–Receptor Interactions

by Marina Mirchandani-Duque, Malak Choucri, Juan C. Hernández-Mondragón, Minerva Crespo-Ramírez, Catalina Pérez-Olives, Luca Ferraro, Rafael Franco, Miguel Pérez de la Mora, Kjell Fuxe and Dasiel O. Borroto-Escuela

Membranes 2024, 14(5), 96; https://doi.org/10.3390/membranes14050096 - 25 Apr 2024

Cited by 1 | Viewed by 2168

Abstract

Bioluminescence and fluorescence resonance energy transfer (BRET and FRET) together with the proximity ligation method revealed the existence of G-protein-coupled receptors, Ionotropic and Receptor tyrosine kinase heterocomplexes, e.g., A2AR–D2R, GABAA–D5R, and FGFR1–5-HT1AR heterocomplexes. Molecular integration takes place through allosteric receptor–receptor interactions in heteroreceptor [...] Read more.

Bioluminescence and fluorescence resonance energy transfer (BRET and FRET) together with the proximity ligation method revealed the existence of G-protein-coupled receptors, Ionotropic and Receptor tyrosine kinase heterocomplexes, e.g., A2AR–D2R, GABAA–D5R, and FGFR1–5-HT1AR heterocomplexes. Molecular integration takes place through allosteric receptor–receptor interactions in heteroreceptor complexes of synaptic and extra-synaptic regions. It involves the modulation of receptor protomer recognition, signaling and trafficking, as well as the modulation of behavioral responses. Allosteric receptor–receptor interactions in hetero-complexes give rise to concepts like meta-modulation and protein modulation. The introduction of receptor–receptor interactions was the origin of the concept of meta-modulation provided by Katz and Edwards in 1999, which stood for the fine-tuning or modulation of nerve cell transmission. In 2000–2010, Ribeiro and Sebastiao, based on a series of papers, provided strong support for their view that adenosine can meta-modulate (fine-tune) synaptic transmission through adenosine receptors. However, another term should also be considered: protein modulation, which is the key feature of allosteric receptor–receptor interactions leading to learning and consolidation by novel adapter proteins to memory. Finally, it must be underlined that allosteric receptor–receptor interactions and their involvement both in brain disease and its treatment are of high interest. Their pathophysiological relevance has been obtained, especially for major depressive disorder, cocaine use disorder, and Parkinson’s disease. Full article

(This article belongs to the Section Biological Membrane Composition and Structures)

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12 pages, 2897 KiB

Open AccessArticle

Preparation and Investigation of Cellulose Acetate/Gelatin Janus Nanofiber Wound Dressings Loaded with Zinc Oxide or Curcumin for Enhanced Antimicrobial Activity

by Tianyue Huang, YuE Zeng, Chaofei Li, Zhengqing Zhou, Yukang Liu, Jie Xu, Lean Wang, Deng-Guang Yu and Ke Wang

Membranes 2024, 14(5), 95; https://doi.org/10.3390/membranes14050095 - 23 Apr 2024

Cited by 6 | Viewed by 1671

Abstract

The skin, as the largest organ, serves as a protective barrier against external stimuli. However, when the skin is injured, wound healing becomes a complex process influenced by physiological conditions, bacterial infections, and inflammation. To improve the process of wound healing, a variety [...] Read more.

The skin, as the largest organ, serves as a protective barrier against external stimuli. However, when the skin is injured, wound healing becomes a complex process influenced by physiological conditions, bacterial infections, and inflammation. To improve the process of wound healing, a variety of wound dressings with antibacterial qualities have been created. Electrospun nanofibers have gained significant attention in wound dressing research due to their large specific surface area and unique structure. One interesting method for creating Janus-structured nanofibers is side-by-side electrospinning. This work used side-by-side electrospinning to make cellulose acetate/gelatin Janus nanofibers. Curcumin and zinc oxide nanoparticles were added to these nanofibers. We studied Janus nanofibers’ physicochemical characteristics and abilities to regulate small-molecule medication release. Janus nanofibers coated with zinc oxide nanoparticles and curcumin were also tested for antibacterial activity. The Janus nanofibers with specified physicochemical characteristics were successfully fabricated. Nanofibers released small-molecule medicines in a controlled manner. Additionally, the Janus nanofibers loaded with curcumin exhibited excellent antibacterial capabilities. This research contributes to the development of advanced wound dressings for promoting wound healing and combating bacterial infections. Full article

(This article belongs to the Special Issue Advances in Membranes Fabricated via Electrospinning)

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