Membranes

12 pages, 828 KiB

Open AccessArticle

Potent Acrylamide Determination in Food Products Using Ion-Selective Electrode Technique

by Sabry Khalil, Alaa El-Beltagy and Mohamed El-Sharnouby

Membranes 2021, 11(8), 645; https://doi.org/10.3390/membranes11080645 - 23 Aug 2021

Cited by 3 | Viewed by 2225

A potent selective acrylamide liquid sensor based on the reaction of acrylamide with 2-(5-Bromo-2-pyridylazo)-5-[N-n-Propyl-N-(3-Sulfopropyl) amino] aniline reagent is successfully designed. The characteristics slope (52.33 mV/decade), linearity usable range from 1.0 × 10⁻⁷–1.0 × 10⁻¹ molar, limit of detection (1.6 × [...] Read more.

A potent selective acrylamide liquid sensor based on the reaction of acrylamide with 2-(5-Bromo-2-pyridylazo)-5-[N-n-Propyl-N-(3-Sulfopropyl) amino] aniline reagent is successfully designed. The characteristics slope (52.33 mV/decade), linearity usable range from 1.0 × 10⁻⁷–1.0 × 10⁻¹ molar, limit of detection (1.6 × 10⁻⁸) molar, selectivity attitude to several inorganic cations, amino acids and sugars, time of response (8 s), lifetime (four months), pH effect on the electrode potential and the basic validation parameters were studied. The desirable pH applicable range was 3.0–6.5, and the restraint of the developed sensor is independent on this working pH range. The deployed electrode was effectively applied for rapid inexpensive analysis of acrylamide cations in food products with comparison to high-performance liquid chromatographic method and the results were agreeable with each other. The obtained data by the suggested electrode were treated statistically and compared with the various recently published acrylamide sensors. Full article

(This article belongs to the Section Membrane Applications)

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14 pages, 839 KiB

Open AccessArticle

Comparisons of Outcomes between Patients with Direct and Indirect Acute Respiratory Distress Syndrome Receiving Extracorporeal Membrane Oxygenation

by Li-Chung Chiu, Li-Pang Chuang, Shih-Wei Lin, Hsin-Hsien Li, Shaw-Woei Leu, Ko-Wei Chang, Chi-Hsien Huang, Tzu-Hsuan Chiu, Huang-Pin Wu, Feng-Chun Tsai, Chung-Chi Huang, Han-Chung Hu and Kuo-Chin Kao

Membranes 2021, 11(8), 644; https://doi.org/10.3390/membranes11080644 - 22 Aug 2021

Cited by 3 | Viewed by 2191

Abstract

Acute respiratory distress syndrome (ARDS) is a heterogeneous syndrome caused by direct (local damage to lung parenchyma) or indirect lung injury (insults from extrapulmonary sites with acute systemic inflammatory response), the clinical and biological complexity can have a profound effect on clinical outcomes. [...] Read more.

Acute respiratory distress syndrome (ARDS) is a heterogeneous syndrome caused by direct (local damage to lung parenchyma) or indirect lung injury (insults from extrapulmonary sites with acute systemic inflammatory response), the clinical and biological complexity can have a profound effect on clinical outcomes. We performed a retrospective analysis of 152 severe ARDS patients receiving extracorporeal membrane oxygenation (ECMO). Our objective was to assess the differences in clinical characteristics and outcomes of direct and indirect ARDS patients receiving ECMO. Overall hospital mortality was 53.3%. A total of 118 patients were assigned to the direct ARDS group, and 34 patients were assigned to the indirect ARDS group. The 28-, 60-, and 90-day hospital mortality rates were significantly higher among indirect ARDS patients (all p < 0.05). Cox regression models demonstrated that among direct ARDS patients, diabetes mellitus, immunocompromised status, ARDS duration before ECMO, and SOFA score during the first 3 days of ECMO were independently associated with mortality. In indirect ARDS patients, SOFA score and dynamic compliance during the first 3 days of ECMO were independently associated with mortality. Our findings revealed that among patients receiving ECMO, direct and indirect subphenotypes of ARDS have distinct clinical outcomes and different predictors for mortality. Full article

(This article belongs to the Special Issue Strategies and Concepts of Extracorporeal Life Support (ECLS))

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16 pages, 3982 KiB

Open AccessArticle

Application of Coagulation–Membrane Rotation to Improve Ultrafiltration Performance in Drinking Water Treatment

by Hongjian Yu, Weipeng Huang, Huachen Liu, Tian Li, Nianping Chi, Huaqiang Chu and Bingzhi Dong

Membranes 2021, 11(8), 643; https://doi.org/10.3390/membranes11080643 - 21 Aug 2021

Cited by 4 | Viewed by 2758

Abstract

The combination of conventional and advanced water treatment is now widely used in drinking water treatment. However, membrane fouling is still the main obstacle to extend its application. In this study, the impact of the combination of coagulation and ultrafiltration (UF) membrane rotation [...] Read more.

The combination of conventional and advanced water treatment is now widely used in drinking water treatment. However, membrane fouling is still the main obstacle to extend its application. In this study, the impact of the combination of coagulation and ultrafiltration (UF) membrane rotation on both fouling control and organic removal of macro (sodium alginate, SA) and micro organic matters (tannic acid, TA) was studied comprehensively to evaluate its applicability in drinking water treatment. The results indicated that membrane rotation could generate shear stress and vortex, thus effectively reducing membrane fouling of both SA and TA solutions, especially for macro SA organics. With additional coagulation, the membrane fouling could be further reduced through the aggregation of mediate and macro organic substances into flocs and elimination by membrane retention. For example, with the membrane rotation speed of 60 r/min, the permeate flux increased by 90% and the organic removal by 35% in SA solution, with 40 mg/L coagulant dosage, with an additional 70% increase of flux and 5% increment of organic removal to 80% obtained. However, too much shear stress could intensify the potential of fiber breakage at the potting, destroying the flocs and resulting in the reduction of permeate flux and deterioration of effluent quality. Finally, the combination of coagulation and membrane rotation would lead to the shaking of the cake layer, which is beneficial for fouling mitigation and prolongation of membrane filtration lifetime. This study provides useful information on applying the combined process of conventional coagulation and the hydrodynamic shear force for drinking water treatment, which can be further explored in the future. Full article

(This article belongs to the Special Issue Membrane Separation Process in Wastewater and Water Purification)

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9 pages, 2179 KiB

Open AccessArticle

Graphene/Fe₃O₄ Nanocomposite as a Promising Material for Chemical Current Sources: A Theoretical Study

by Vladislav V. Shunaev and Olga E. Glukhova

Membranes 2021, 11(8), 642; https://doi.org/10.3390/membranes11080642 - 20 Aug 2021

Cited by 3 | Viewed by 2270

Abstract

The outstanding mechanical and conductive properties of graphene and high theoretical capacity of magnetite make a composite based on these two structures a prospective material for application in flexible energy storage devices. In this study using quantum chemical methods, the influence of magnetite [...] Read more.

The outstanding mechanical and conductive properties of graphene and high theoretical capacity of magnetite make a composite based on these two structures a prospective material for application in flexible energy storage devices. In this study using quantum chemical methods, the influence of magnetite concentration on energetic and electronic parameters of graphene/Fe₃O₄ composites is estimated. It is found that the addition of magnetite to pure graphene significantly changes its zone structure and capacitive properties. By varying the concentration of Fe₃O₄ particles, it is possible to tune the capacity of the composite for application in hybrid and symmetric supercapacitors. Full article

(This article belongs to the Special Issue Flexible Membranes for Batteries and Supercapacitor Applications)

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20 pages, 3867 KiB

Open AccessArticle

Effects of an Alternating Magnetic Field towards Dispersion of α-Fe₂O₃/TiO₂ Magnetic Filler in PPO_dm Polymer for CO₂/CH₄ Gas Separation

by Yun Kee Yap and Pei Ching Oh

Membranes 2021, 11(8), 641; https://doi.org/10.3390/membranes11080641 - 20 Aug 2021

Cited by 4 | Viewed by 2534

Abstract

Magnetic-field-induced dispersion of magnetic fillers has been proven to improve the gas separation performance of mixed matrix membranes (MMMs). However, the magnetic field induced is usually in a horizontal or vertical direction. Limited study has been conducted on the effects of alternating magnetic [...] Read more.

Magnetic-field-induced dispersion of magnetic fillers has been proven to improve the gas separation performance of mixed matrix membranes (MMMs). However, the magnetic field induced is usually in a horizontal or vertical direction. Limited study has been conducted on the effects of alternating magnetic field (AMF) direction towards the dispersion of particles. Thus, this work focuses on the incorporation and dispersion of ferromagnetic iron oxide–titanium (IV) dioxide (αFe₂O₃/TiO₂) particles in a poly (2,6-dimethyl-1,4-phenylene) oxide (PPO_dm) membrane via an AMF to investigate its effect on the magnetic filler dispersion and correlation towards gas separation performance. The fillers were incorporated into PPO_dm polymer via a spin-coating method at a 1, 3, and 5 wt% filler loading. The MMM with the 3 wt% loading showed the best performance in terms of particle dispersion and gas separation performance. The three MMMs were refabricated in an alternating magnetic field, and the MMM with the 3 wt% loading presented the best performance. The results display an increment in selectivity by 100% and a decrement in CO₂ permeability by 97% to an unmagnetized MMM for the 3 wt% loading. The degree of filler dispersion was quantified and measured using Area Disorder of Delaunay Triangulation mapped onto the filler on binarized MMM images. The results indicate that the magnetized MMM presents a greater degree of dispersion than the unmagnetized MMM. Full article

(This article belongs to the Special Issue Special Issue in Honor of Professor Ahmad Fauzi Ismail)

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13 pages, 6420 KiB

Open AccessArticle

Effects of Processing Conditions and Plasticizing-Reinforcing Modification on the Crystallization and Physical Properties of PLA Films

by Shuo Wang, Baodong Liu, Yingying Qin and Hongge Guo

Membranes 2021, 11(8), 640; https://doi.org/10.3390/membranes11080640 - 20 Aug 2021

Cited by 11 | Viewed by 3115

Abstract

The polylactic acid (PLA) resin Ingeo 4032D was selected as the research object. Epoxy soybean oil (ESO) and zeolite (3A molecular sieve) were used as plasticizer and reinforcing filler, respectively, for PLA blend modification. The mixture was granulated in an extruder and then [...] Read more.

The polylactic acid (PLA) resin Ingeo 4032D was selected as the research object. Epoxy soybean oil (ESO) and zeolite (3A molecular sieve) were used as plasticizer and reinforcing filler, respectively, for PLA blend modification. The mixture was granulated in an extruder and then blown to obtain films under different conditions to determine the optimum processing temperatures and screw rotation. Then, the thermal behaviour, crystallinity, optical transparency, micro phase structure and physical properties of the film were investigated. The results showed that with increasing zeolite content, the crystallization behaviour of PLA changed, and the haze of the film increased from 5% to 40% compared to the pure PLA film. Zeolite and ESO dispersed in the PLA matrix played a role in toughening and strengthening. The PLA/8 wt% zeolite/3 wt% ESO film had the highest longitudinal tensile strength at 77 MPa. The PLA/2 wt% zeolite/3 wt% ESO film had the highest longitudinal elongation at 13%. The physical properties depended heavily on the dispersion of zeolite and ESO in the matrix. Full article

(This article belongs to the Special Issue Theoretical and Experimental Investigation of the Mass and Heat Transfers in Membrane Separation Processes)

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11 pages, 1704 KiB

Open AccessArticle

Combined Nanofiltration and Thermocatalysis for the Simultaneous Degradation of Micropollutants, Fouling Mitigation and Water Purification

by Katarzyna Janowska, Xianzheng Ma, Vittorio Boffa, Mads Koustrup Jørgensen and Victor M. Candelario

Membranes 2021, 11(8), 639; https://doi.org/10.3390/membranes11080639 - 19 Aug 2021

Cited by 6 | Viewed by 2590

Abstract

Due to progressive limitation of access to clean drinkable water, it is nowadays a priority to find an effective method of water purification from those emerging organic contaminants, which might have potentially harmful and irreversible effects on living organisms and environment. This manuscript [...] Read more.

Due to progressive limitation of access to clean drinkable water, it is nowadays a priority to find an effective method of water purification from those emerging organic contaminants, which might have potentially harmful and irreversible effects on living organisms and environment. This manuscript reports the development of a new strategy for water purification, which combines a novel and recently developed Al₂O₃-doped silica nanofiltration membrane with a thermocatalytic perovskite, namely cerium-doped strontium ferrate (CSF). The thermocatalytic activity of CSF offers the opportunity to degrade organic pollutants with no light and without input of chemical oxidants, providing simplicity of operation. Moreover, our studies on real samples of secondary effluent from wastewater treatment showed that the thermocatalyst has the ability to degrade also part of the non-toxic organic matter, which allows for reducing the chemical oxygen demand of the retentate and mitigating membrane fouling during filtration. Therefore, the new technology is effective in the production of clean feed and permeate and has a potential to be used in degradation of micropollutants in water treatment. Full article

(This article belongs to the Special Issue Advanced Membrane Processes in Water Treatment)

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10 pages, 4277 KiB

Open AccessReview

Membrane-Based Solutions for the Polish Coal Mining Industry

by Krzysztof Mitko and Marian Turek

Membranes 2021, 11(8), 638; https://doi.org/10.3390/membranes11080638 - 18 Aug 2021

Cited by 7 | Viewed by 2653

Abstract

Poland still relies largely on coal for energy generation, which creates environmental problems connected to the mining process, particularly the issue of saline waste water discharge. Membrane-based zero liquid discharge systems can be employed to recover important resources from coal mine waste waters, [...] Read more.

Poland still relies largely on coal for energy generation, which creates environmental problems connected to the mining process, particularly the issue of saline waste water discharge. Membrane-based zero liquid discharge systems can be employed to recover important resources from coal mine waste waters, such as demineralized water, salt, magnesium hydroxide, and gypsum. In this paper, we present a historical overview of proposed membrane-based solutions for the Polish coal mining industry and discuss possible further areas of research. Full article

(This article belongs to the Special Issue State-of-the-Art Membrane Science and Technology in Poland 2021-2022)

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12 pages, 3329 KiB

Open AccessArticle

Preparation of Hydrophobic PET Track-Etched Membranes for Separation of Oil–Water Emulsion

by Ilya V. Korolkov, Asiya R. Narmukhamedova, Galina B. Melnikova, Indira B. Muslimova, Arman B. Yeszhanov, Zh K. Zhatkanbayeva, Sergei A. Chizhik and Maxim V. Zdorovets

Membranes 2021, 11(8), 637; https://doi.org/10.3390/membranes11080637 - 17 Aug 2021

Cited by 20 | Viewed by 3439

Abstract

The paper describes the separation of an oil–water emulsion by filtration using poly(ethylene terephthalate) track-etched membranes (PET TeMs) with regular pore geometry and narrow pore size distribution. PET TeMs were modified with trichloro(octyl)silane to increase their hydrophobic properties. Conditions for the modification of [...] Read more.

The paper describes the separation of an oil–water emulsion by filtration using poly(ethylene terephthalate) track-etched membranes (PET TeMs) with regular pore geometry and narrow pore size distribution. PET TeMs were modified with trichloro(octyl)silane to increase their hydrophobic properties. Conditions for the modification of PET TeMs with trichloro(octyl)silane were investigated. The results of changes in the pore diameters and the contact angle depend on the concentration of trichloro(octyl)silane and the soaking time are presented. The obtained samples were characterized by FTIR, AFM, SEM-EDX and gas-permeability test. Chloroform–water and cetane–water emulsions have been used as a test liquid for oil–water separation. Full article

(This article belongs to the Special Issue Advanced Polymeric Membranes for Energy & Environment)

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21 pages, 5006 KiB

Open AccessArticle

Effective Perturbations of the Amplitude, Gating, and Hysteresis of I_K(DR) Caused by PT-2385, an HIF-2α Inhibitor

by Hung-Tsung Hsiao, Guan-Ling Lu, Yen-Chin Liu and Sheng-Nan Wu

Membranes 2021, 11(8), 636; https://doi.org/10.3390/membranes11080636 - 17 Aug 2021

Cited by 5 | Viewed by 2337

Abstract

PT-2385 is currently regarded as a potent and selective inhibitor of hypoxia-inducible factor-2α (HIF-2α), with potential antineoplastic activity. However, the membrane ion channels changed by this compound are obscure, although it is reasonable to assume that the compound might act on surface membrane [...] Read more.

PT-2385 is currently regarded as a potent and selective inhibitor of hypoxia-inducible factor-2α (HIF-2α), with potential antineoplastic activity. However, the membrane ion channels changed by this compound are obscure, although it is reasonable to assume that the compound might act on surface membrane before entering the cell´s interior. In this study, we intended to explore whether it and related compounds make any adjustments to the plasmalemmal ionic currents of pituitary tumor (GH₃) cells and human 13-06-MG glioma cells. Cell exposure to PT-2385 suppressed the peak or late amplitude of delayed-rectifier K⁺ current (I_K(DR)) in a time- and concentration-dependent manner, with IC₅₀ values of 8.1 or 2.2 µM, respectively, while the K_D value in PT-2385-induced shortening in the slow component of I_K(DR) inactivation was estimated to be 2.9 µM. The PT-2385-mediated block of I_K(DR) in GH₃ cells was little-affected by the further application of diazoxide, cilostazol, or sorafenib. Increasing PT-2385 concentrations shifted the steady-state inactivation curve of I_K(DR) towards a more hyperpolarized potential, with no change in the gating charge of the current, and also prolonged the time-dependent recovery of the I_K(DR) block. The hysteretic strength of I_K(DR) elicited by upright or inverted isosceles-triangular ramp voltage was decreased during exposure to PT-2385; meanwhile, the activation energy involved in the gating of I_K(DR) elicitation was noticeably raised in its presence. Alternatively, the presence of PT-2385 in human 13-06-MG glioma cells effectively decreased the amplitude of I_K(DR). Considering all of the experimental results together, the effects of PT-2385 on ionic currents demonstrated herein could be non-canonical and tend to be upstream of the inhibition of HIF-2α. This action therefore probably contributes to down-streaming mechanisms through the changes that it or other structurally resemblant compounds lead to in the perturbations of the functional activities of pituitary cells or neoplastic astrocytes, in the case that in vivo observations occur. Full article

(This article belongs to the Special Issue Molecular Mechanism of Cellular Membranes for Signal Transduction)

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14 pages, 2454 KiB

Open AccessArticle

A Theoretical Analysis on a Multi-Bed Pervaporation Membrane Reactor during Levulinic Acid Esterification Using the Computational Fluid Dynamic Method

by Milad Ghahremani, Kamran Ghasemzadeh, Elham Jalilnejad and Adolfo Iulianelli

Membranes 2021, 11(8), 635; https://doi.org/10.3390/membranes11080635 - 17 Aug 2021

Cited by 3 | Viewed by 2044

Abstract

Pervaporation is a peculiar membrane separation process, which is considered for integration with a variety of reactions in promising new applications. Pervaporation membrane reactors have some specific uses in sustainable chemistry, such as the esterification processes. This theoretical study based on the computational [...] Read more.

Pervaporation is a peculiar membrane separation process, which is considered for integration with a variety of reactions in promising new applications. Pervaporation membrane reactors have some specific uses in sustainable chemistry, such as the esterification processes. This theoretical study based on the computational fluid dynamics method aims to evaluate the performance of a multi-bed pervaporation membrane reactor (including poly (vinyl alcohol) membrane) to produce ethyl levulinate as a significant fuel additive, coming from the esterification of levulinic acid. For comparison, an equivalent multi-bed traditional reactor is also studied at the same operating conditions of the aforementioned pervaporation membrane reactor. A computational fluid dynamics model was developed and validated by experimental literature data. The effects of reaction temperature, catalyst loading, feed molar ratio, and feed flow rate on the reactor’s performance in terms of levulinic acid conversion and water removal were hence studied. The simulations indicated that the multi-bed pervaporation membrane reactor results to be the best solution over the multi-bed traditional reactor, presenting the best simulation results at 343 K, 2 bar, catalyst loading 8.6 g, feed flow rate 7 mm³/s, and feed molar ratio 3 with levulinic acid conversion equal to 95.3% and 91.1% water removal. Full article

(This article belongs to the Special Issue State-of-the-Art Membrane Science and Technology in Italy 2021, 2022)

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9 pages, 3288 KiB

Open AccessArticle

HiLo Based Line Scanning Temporal Focusing Microscopy for High-Speed, Deep Tissue Imaging

by Ruheng Shi, Yuanlong Zhang, Tiankuang Zhou and Lingjie Kong

Membranes 2021, 11(8), 634; https://doi.org/10.3390/membranes11080634 - 17 Aug 2021

Cited by 1 | Viewed by 2579

Abstract

High-speed, optical-sectioning imaging is highly desired in biomedical studies, as most bio-structures and bio-dynamics are in three-dimensions. Compared to point-scanning techniques, line scanning temporal focusing microscopy (LSTFM) is a promising method that can achieve high temporal resolution while maintaining a deep penetration depth. [...] Read more.

High-speed, optical-sectioning imaging is highly desired in biomedical studies, as most bio-structures and bio-dynamics are in three-dimensions. Compared to point-scanning techniques, line scanning temporal focusing microscopy (LSTFM) is a promising method that can achieve high temporal resolution while maintaining a deep penetration depth. However, the contrast and axial confinement would still be deteriorated in scattering tissue imaging. Here, we propose a HiLo-based LSTFM, utilizing structured illumination to inhibit the fluorescence background and, thus, enhance the image contrast and axial confinement in deep imaging. We demonstrate the superiority of our method by performing volumetric imaging of neurons and dynamical imaging of microglia in mouse brains in vivo. Full article

(This article belongs to the Special Issue Toolbox Development for Cellular Endomembrane Studies in the Living System: Fluorescence Probes and Advanced Imaging Strategies)

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28 pages, 11978 KiB

Open AccessArticle

Reactional Processes on Osmium–Polymeric Membranes for 5–Nitrobenzimidazole Reduction

by Aurelia Cristina Nechifor, Alexandru Goran, Vlad-Alexandru Grosu, Andreia Pîrțac, Paul Constantin Albu, Ovidiu Oprea, Alexandra Raluca Grosu, Dumitru Pașcu, Florentina Mihaela Păncescu, Gheorghe Nechifor, Szidonia-Katalin Tanczos and Simona Gabriela Bungău

Membranes 2021, 11(8), 633; https://doi.org/10.3390/membranes11080633 - 17 Aug 2021

Cited by 6 | Viewed by 2694

Abstract

Membranes are associated with the efficient processes of separation, concentration and purification, but a very important aspect of them is the realization of a reaction process simultaneously with the separation process. From a practical point of view, chemical reactions have been introduced in [...] Read more.

Membranes are associated with the efficient processes of separation, concentration and purification, but a very important aspect of them is the realization of a reaction process simultaneously with the separation process. From a practical point of view, chemical reactions have been introduced in most membrane systems: with on-liquid membranes, with inorganic membranes or with polymeric and/or composite membranes. This paper presents the obtaining of polymeric membranes containing metallic osmium obtained in situ. Cellulose acetate (CA), polysulfone (PSf) and polypropylene hollow fiber membranes (PPM) were used as support polymer membranes. The metallic osmium is obtained directly onto the considered membranes using a solution of osmium tetroxide (OsO4), dissolved in tert–butyl alcohol (t–Bu–OH) by reduction with molecular hydrogen. The composite osmium–polymer (Os–P)-obtained membranes were characterized in terms of the morphological and structural points of view: scanning electron microscopy (SEM), high-resolution SEM (HR–SEM), energy-dispersive spectroscopy analysis (EDAX), Fourier Transform Infra-Red (FTIR) spectroscopy, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The process performance was tested for reduction of 5–nitrobenzimidazole to 5–aminobenzimidazole with molecular hydrogen. The paper presents the main aspects of the possible mechanism of transformation of 5–nitrobenzimidazole to 5–aminobenzimidazole with hydrogen gas in the reaction system with osmium–polymer membrane (Os–P). Full article

(This article belongs to the Collection Polymeric Membranes: Science, Materials and Applications)

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21 pages, 3192 KiB

Open AccessEditor’s ChoiceArticle

CeO₂-Blended Cellulose Triacetate Mixed-Matrix Membranes for Selective CO₂ Separation

by Chhabilal Regmi, Saeed Ashtiani, Zdeněk Sofer, Zdeněk Hrdlička, Filip Průša, Ondřej Vopička and Karel Friess

Membranes 2021, 11(8), 632; https://doi.org/10.3390/membranes11080632 - 17 Aug 2021

Cited by 14 | Viewed by 2896

Abstract

Due to the high affinity of ceria (CeO₂) towards carbon dioxide (CO₂) and the high thermal and mechanical properties of cellulose triacetate (CTA) polymer, mixed-matrix CTA-CeO₂ membranes were fabricated. A facile solution-casting method was used for the fabrication [...] Read more.

Due to the high affinity of ceria (CeO₂) towards carbon dioxide (CO₂) and the high thermal and mechanical properties of cellulose triacetate (CTA) polymer, mixed-matrix CTA-CeO₂ membranes were fabricated. A facile solution-casting method was used for the fabrication process. CeO₂ nanoparticles at concentrations of 0.32, 0.64 and 0.9 wt.% were incorporated into the CTA matrix. The physico-chemical properties of the membranes were evaluated by SEM-EDS, XRD, FTIR, TGA, DSC and strain-stress analysis. Gas sorption and permeation affinity were evaluated using different single gases. The CTA-CeO₂ (0.64) membrane matrix showed a high affinity towards CO₂ sorption. Almost complete saturation of CeO₂ nanoparticles with CO₂ was observed, even at low pressure. Embedding CeO₂ nanoparticles led to increased gas permeability compared to pristine CTA. The highest gas permeabilities were achieved with 0.64 wt.%, with a threefold increase in CO₂ permeability as compared to pristine CTA membranes. Unwanted aggregation of the filler nanoparticles was observed at a 0.9 wt.% concentration of CeO₂ and was reflected in decreased gas permeability compared to lower filler loadings with homogenous filler distributions. The determined gas selectivity was in the order CO₂/CH₄ > CO₂/N₂ > O₂/N₂ > H₂/CO₂ and suggests the potential of CTA-CeO₂ membranes for CO₂ separation in flue/biogas applications. Full article

(This article belongs to the Section Polymeric Membranes)

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16 pages, 6301 KiB

Open AccessArticle

Linking the Tuneability and Defouling of Electrically Conductive Polyaniline/Exfoliated Graphite Composite Membranes

by Lili Xu, Kunpeng Wang, Jun Wang and Darrell Alec Patterson

Membranes 2021, 11(8), 631; https://doi.org/10.3390/membranes11080631 - 17 Aug 2021

Cited by 2 | Viewed by 2181

Abstract

Stimuli responsive membranes, which are able to respond to environmental stimuli, are attracting ever-increasing interests. In this study, we blended exfoliated graphite (EG) into the polyaniline (PANI) and developed PANI/EG composite membranes. The properties of the new generated membranes, especially the stimuli response [...] Read more.

Stimuli responsive membranes, which are able to respond to environmental stimuli, are attracting ever-increasing interests. In this study, we blended exfoliated graphite (EG) into the polyaniline (PANI) and developed PANI/EG composite membranes. The properties of the new generated membranes, especially the stimuli response properties (e.g., electrical tuneability, deformation), were studied. The fouling removal ability of the membrane under applied electrical potential was also investigated by using bovine serum albumin (BSA) as a model foulant. A flat membrane with defect-free surface and good adhesion to the support layer was formed by non-solvent induced phase separation method. The electrical conductivity of the formed PANI/EG composite membrane was (5.10 ± 0.27) ×10⁻⁴ S cm⁻¹. The dynamic droplet penetration rate through the membranes showed an increase under applied electrical potential, which gives a preliminary quantitative indication of the electrical tuneability of the membranes. The membrane deformation appeared at a fast response under applied potential and recovered to its original position immediately when removing the applied potential. The application of electrical potential led to the removal of BSA foulant from the membrane surface as indicated by the increase in permeance of the fouled membrane on cleaning with 46.2% flux recovery ratio and increased BSA concentration in the wash solution. The electrically conductive PANI/EG composite membranes are able to respond to electrical stimuli, enabling a new range of potential applications including externally tuneability and in situ removal and control of fouling. Full article

(This article belongs to the Special Issue Composite Conducting Membranes: Preparation, Properties, and Applications)

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17 pages, 27463 KiB

Open AccessArticle

Modified Zeolite/Polysulfone Mixed Matrix Membrane for Enhanced CO₂/CH₄ Separation

by Lanisha Devi Anbealagan, Tiffany Yit Siew Ng, Thiam Leng Chew, Yin Fong Yeong, Siew Chun Low, Yit Thai Ong, Chii-Dong Ho and Zeinab Abbas Jawad

Membranes 2021, 11(8), 630; https://doi.org/10.3390/membranes11080630 - 16 Aug 2021

Cited by 12 | Viewed by 3526

Abstract

In recent years, mixed matrix membranes (MMMs) have received worldwide attention for their potential to offer superior gas permeation and separation performance involving CO₂ and CH₄. However, fabricating defect-free MMMs still remains as a challenge where the incorporation of fillers [...] Read more.

In recent years, mixed matrix membranes (MMMs) have received worldwide attention for their potential to offer superior gas permeation and separation performance involving CO₂ and CH₄. However, fabricating defect-free MMMs still remains as a challenge where the incorporation of fillers into MMMs has usually led to some issues including formation of undesirable interfacial voids, which may jeopardize the gas separation performance of the MMMs. This current work investigated the incorporation of zeolite RHO and silane-modified zeolite RHO (NH₂–RHO) into polysulfone (PSf) based MMMs with the primary aim of enhancing the membrane’s gas permeation and separation performance. The synthesized zeolite RHO, NH₂–RHO, and fabricated membranes were characterized by X-ray diffraction (XRD) analysis, Fourier transform infrared-attenuated total reflection (FTIR-ATR), thermogravimetric analysis (TGA) and field emission scanning election microscopy (FESEM). The effects of zeolite loading in the MMMs on the CO₂/CH₄ separation performance were investigated. By incorporating 1 wt% of zeolite RHO into the MMMs, the CO₂ permeability and ideal CO₂/CH₄ selectivity slightly increased by 4.2% and 2.7%, respectively, compared to that of a pristine PSf membrane. On the other hand, a significant enhancement of 45% in ideal CO₂/CH₄ selectivity was attained by MMMs incorporated with 2 wt% of zeolite NH₂-RHO compared to a pristine PSf membrane. Besides, all MMMs incorporated with zeolite NH₂-RHO displayed higher ideal CO₂/CH₄ selectivity than that of the MMMs incorporated with zeolite RHO. By incorporating 1–3 wt% zeolite NH₂-RHO into PSf matrix, MMMs without interfacial voids were successfully fabricated. Consequently, significant enhancement in ideal CO₂/CH₄ selectivity was enabled by the incorporation of zeolite NH₂–RHO into MMMs. Full article

(This article belongs to the Special Issue Special Issue in Honor of Professor Ahmad Fauzi Ismail)

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3 pages, 193 KiB

Open AccessEditorial

Applications of Membranes for Sustainability

by Veeriah Jegatheesan, Chettiyappan Visvanathan, Li Shu, Faisal I. Hai and Ludovic F. Dumée

Membranes 2021, 11(8), 629; https://doi.org/10.3390/membranes11080629 - 16 Aug 2021

Cited by 1 | Viewed by 1997

Abstract

Applications of membranes in water and wastewater treatment, desalination, as well as other purification processes, have become more widespread over the past few decades [...] Full article

(This article belongs to the Special Issue CESE-2019: Applications of Membranes for Sustainability)

10 pages, 2071 KiB

Open AccessCommunication

Preparation and Desalination Performance of PA/UiO-66/PES Composite Membranes

by Dai Xuan Trinh, Ngo Nghia Pham, Patchanee Chammingkwan and Toshiaki Taniike

Membranes 2021, 11(8), 628; https://doi.org/10.3390/membranes11080628 - 16 Aug 2021

Cited by 5 | Viewed by 2933

Abstract

UiO-66 nanoparticles are considered highly potential fillers for the application in desalination membranes. In this study, UiO-66 nanoparticles were anchored to PES membrane substrates, which were subsequently subjected to the interfacial polymerization reaction to coat a layer of polyamide (PA) on their surface. [...] Read more.

UiO-66 nanoparticles are considered highly potential fillers for the application in desalination membranes. In this study, UiO-66 nanoparticles were anchored to PES membrane substrates, which were subsequently subjected to the interfacial polymerization reaction to coat a layer of polyamide (PA) on their surface. For comparison, a blank membrane incorporating no UiO-66 and a reference membrane incorporating ZrO₂ (instead of UiO-66) were prepared. All prepared membranes were tested for their desalination performance. The membranes containing UiO-66 were found to outperform the blank and the reference counterparts. The reason for this outperformance is possibly attributed to the hydrophilicity of UiO-66 nanoparticles and the presence of nanochannels in their structure. Full article

(This article belongs to the Special Issue Development, Investigation and Application of Novel Polymer Membranes)

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13 pages, 5638 KiB

Open AccessArticle

Development of Methanol Permselective FAU-Type Zeolite Membranes and Their Permeation and Separation Performances

by Ayumi Ikeda, Chie Abe, Wakako Matsuura and Yasuhisa Hasegawa

Membranes 2021, 11(8), 627; https://doi.org/10.3390/membranes11080627 - 15 Aug 2021

Cited by 5 | Viewed by 3184

Abstract

The separation of non-aqueous mixtures is important for chemical production, and zeolite membranes have great potential for energy-efficient separation. In this study, the influence of the framework structure and composition of zeolites on the permeation and separation performance of methanol through zeolite membranes [...] Read more.

The separation of non-aqueous mixtures is important for chemical production, and zeolite membranes have great potential for energy-efficient separation. In this study, the influence of the framework structure and composition of zeolites on the permeation and separation performance of methanol through zeolite membranes were investigated to develop a methanol permselective zeolite membrane. As a result, the FAU-type zeolite membrane prepared using a solution with a composition of 10 SiO₂:1 Al₂O₃:17 Na₂O:1000 H₂O showed the highest permeation flux of 86,600 μmol m⁻² s⁻¹ and a separation factor of 6020 for a 10 wt% methanol/methyl hexanoate mixture at 353 K. The membrane showed a molecular sieving effect, reducing the single permeation flux of alcohol with molecular size for single-component alcohols. Moreover, the permeation flux of methanol and the separation factor increased with an increase in the carbon number of the alcohols and methyl esters containing 10 wt% methanol. In this study, the permeation behavior of FAU-type zeolite membranes was also discussed based on permeation data. These results suggest that the FAU-type zeolite membrane has the potential to separate organic solvent mixtures, such as solvent recycling and membrane reactors. Full article

(This article belongs to the Special Issue State-of-the-Art Membrane Science and Technology in Japan 2021, 2022)

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20 pages, 3111 KiB

Open AccessArticle

Highly Proton-Conducting Membranes Based on Poly(arylene ether)s with Densely Sulfonated and Partially Fluorinated Multiphenyl for Fuel Cell Applications

by Tzu-Sheng Huang, Tung-Li Hsieh, Chih-Ching Lai, Hsin-Yi Wen, Wen-Yao Huang and Mei-Ying Chang

Membranes 2021, 11(8), 626; https://doi.org/10.3390/membranes11080626 - 15 Aug 2021

Cited by 8 | Viewed by 2967

Abstract

Series of partially fluorinated sulfonated poly(arylene ether)s were synthesized through nucleophilic substitution polycondensation from three types of diols and superhydrophobic tetra-trifluoromethyl-substituted difluoro monomers with postsulfonation to obtain densely sulfonated ionomers. The membranes had similar ion exchange capacities of 2.92 ± 0.20 mmol g [...] Read more.

Series of partially fluorinated sulfonated poly(arylene ether)s were synthesized through nucleophilic substitution polycondensation from three types of diols and superhydrophobic tetra-trifluoromethyl-substituted difluoro monomers with postsulfonation to obtain densely sulfonated ionomers. The membranes had similar ion exchange capacities of 2.92 ± 0.20 mmol g⁻¹ and favorable mechanical properties (Young’s moduli of 1.60–1.83 GPa). The membranes exhibited considerable dimensional stability (43.1–122.3% change in area and 42.1–61.5% change in thickness at 80 °C) and oxidative stability (~55.5%). The proton conductivity of the membranes, higher (174.3–301.8 mS cm⁻¹) than that of Nafion 211 (123.8 mS cm⁻¹), was the percent conducting volume corresponding to the water uptake. The membranes were observed to comprise isolated to tailed ionic clusters of size 15–45 nm and 3–8 nm, respectively, in transmission electron microscopy images. A fuel cell containing one such material exhibited high single-cell performance—a maximum power density of 1.32 W cm² and current density of >1600 mA cm⁻² at 0.6 V. The results indicate that the material is a candidate for proton exchange membranes in fuel cell applications. Full article

(This article belongs to the Topic Electromaterials for Environment & Energy)

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9 pages, 839 KiB

Open AccessCommunication

Establishment of a Disaster Management-like System for COVID-19 Patients Requiring Veno-Venous Extracorporeal Membrane Oxygenation in Japan

by Takayuki Ogura, Shinichiro Ohshimo, Keibun Liu, Yoshiaki Iwashita, Satoru Hashimoto and Shinhiro Takeda

Membranes 2021, 11(8), 625; https://doi.org/10.3390/membranes11080625 - 14 Aug 2021

Cited by 12 | Viewed by 3747

Abstract

The coronavirus disease 2019 (COVID-19) pandemic has increased the number of patients who require extracorporeal membrane oxygenation (ECMO). To manage the demand for ECMO, Japan ECMOnet for COVID-19 was developed as a “disaster management-like system”, utilizing the Cross ICU Searchable Information System (CRISIS) [...] Read more.

The coronavirus disease 2019 (COVID-19) pandemic has increased the number of patients who require extracorporeal membrane oxygenation (ECMO). To manage the demand for ECMO, Japan ECMOnet for COVID-19 was developed as a “disaster management-like system”, utilizing the Cross ICU Searchable Information System (CRISIS) database. This study investigated the effect of the establishment of this disaster management-like system in Japan. This was a nationwide retrospective observational study conducted from 1 February to 31 July in 2020. A total of 187 patients with COVID-19 who received ECMO were included. The median age was 60 years (interquartile range, 53–68), the median length of ventilatory support before ECMO was 3 days (1–5), and the median PaO₂ to FiO₂ ratio at ECMO initiation was 86 (71.3–101.5). During the study period, 165 telephone consultations were conducted, including general questions about ECMO. Among them, 44 concerned patients who were already on ECMO or who ultimately received ECMO. Further coordination, including transport and ECMO physician dispatch, was provided for 23 cases. Overall, 125/187 (66.8%) patients were successfully weaned from ECMO. This study demonstrated that Japan has achieved favorable survival outcomes for patients with COVID-19 who received ECMO with a disaster management-like system. Further research on the causes of these outcomes is needed. Full article

(This article belongs to the Section Membrane Applications)

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10 pages, 2452 KiB

Open AccessArticle

The Effect of Strontium-Substituted Hydroxyapatite Nanofibrous Matrix on Osteoblast Proliferation and Differentiation

by Shiao-Wen Tsai, Yu-Wei Hsu, Whei-Lin Pan and Fu-Yin Hsu

Membranes 2021, 11(8), 624; https://doi.org/10.3390/membranes11080624 - 14 Aug 2021

Cited by 14 | Viewed by 2469

Abstract

Natural bone tissue consists primarily of bioapatite and collagen. Synthetic hydroxyapatite (HA) possesses good biocompatibility, bioactivity, and osteoconductivity due to its chemical and biological similarity to bioapatite. Hence, HA has been widely used as a bone graft, cell carrier and drug/gene delivery carrier. [...] Read more.

Natural bone tissue consists primarily of bioapatite and collagen. Synthetic hydroxyapatite (HA) possesses good biocompatibility, bioactivity, and osteoconductivity due to its chemical and biological similarity to bioapatite. Hence, HA has been widely used as a bone graft, cell carrier and drug/gene delivery carrier. Moreover, strontium-substituted hydroxyapatite (SrHA) can enhance osteogenic differentiation and inhibit adipogenic differentiation of mesenchymal stem cells. Hence, SrHA has the potential to be used as a bone graft for bone regeneration. It is widely accepted that cell adhesion and most cellular activities are sensitive to the topography and molecular composition of the matrix. Electrospun polymer or polymer-bioceramic composite nanofibers have been demonstrated to enhance osteoblast differentiation. However, to date, no studies have investigated the effect of nanofibrous bioceramic matrices on osteoblasts. In this study, hydroxyapatite nanofiber (HANF) and strontium-substituted hydroxyapatite nanofiber (SrHANF) matrices were fabricated by electrospinning. The effect of the HANF components on MG63 osteoblast-like cells was evaluated by cell morphology, proliferation, alkaline phosphatase activity (ALP) and gene expression levels of RUNX2, COLI, OCN and BSP. The results showed that MG63 osteoblast-like cells exhibited higher ALP and gene expression levels of RUNX2, COLI, BSP and OCN on the SrHANF matrix than the HANF matrix. Hence, SrHANFs could enhance the differentiation of MG63 osteoblast-like cells. Full article

(This article belongs to the Special Issue Membranes for Tissue Engineering)

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19 pages, 8350 KiB

Open AccessArticle

Preparation of Al-Containing ZSM-58 Zeolite Membranes Using Rapid Thermal Processing for CO₂/CH₄ Mixture Separation

by Eiji Hayakawa and Shuji Himeno

Membranes 2021, 11(8), 623; https://doi.org/10.3390/membranes11080623 - 13 Aug 2021

Cited by 12 | Viewed by 2531

Abstract

The synthesis of DDR-type zeolite membranes faces the problem of cracks that occur on the zeolite membrane due to differences in the thermal expansion coefficient between zeolite and the porous substrate during the detemplating process. In this study, Al-containing ZSM-58 zeolite membranes with [...] Read more.

The synthesis of DDR-type zeolite membranes faces the problem of cracks that occur on the zeolite membrane due to differences in the thermal expansion coefficient between zeolite and the porous substrate during the detemplating process. In this study, Al-containing ZSM-58 zeolite membranes with DDR topology were prepared by rapid thermal processing (RTP), with the aim of developing a reproducible method for preparing DDR zeolite membrane without cracks. Moreover, we verified the influence of RTP before performing conventional thermal calcination (CTC) on ZSM-58 membranes with various silica-to-aluminum (Si/Al) molar ratios. Using the developed method, an Al-containing ZSM-58 membrane without cracks was obtained, along with complete template removal by RTP, and it had higher CO₂/CH₄ selectivity. An all-silica ZSM-58 membrane without cracks was obtained by only using the ozone detemplating method. ZSM-58 crystals and membranes with various Si/Al molar ratios were analyzed by using Fourier-transform infrared (FTIR) spectroscopy to confirm the effects of RTP treatment. Al-containing ZSM-58 zeolites had higher silanol concentrations than all-silica zeolites, confirming many silanol condensations by RTP. The condensation of silanol forms results in the formation of siloxane bonds and stronger resistance to thermal stress; therefore, RTP caused crack suppression in Al-containing ZSM-58 membranes. The results demonstrate that Al-containing ZSM-58 zeolite membranes with high CO₂ permeance and CO₂/CH₄ selectivity and minimal cracking can be produced by using RTP. Full article

(This article belongs to the Special Issue Membranes for Gas Separation and Purification Processes)

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17 pages, 4527 KiB

Open AccessArticle

A Novel Green Diluent for the Preparation of Poly(4-methyl-1-pentene) Membranes via a Thermally-Induced Phase Separation Method

by Yuanhui Tang, Mufei Li, Yakai Lin, Lin Wang, Fangyu Wu and Xiaolin Wang

Membranes 2021, 11(8), 622; https://doi.org/10.3390/membranes11080622 - 13 Aug 2021

Cited by 12 | Viewed by 3138

Abstract

The use of green solvents satisfies safer chemical engineering practices and environmental security. Herein, myristic acid (MA)—a green diluent—was selected to prepare poly- (4-methyl-1-pentene) (PMP) membranes with bicontinuous porous structure via a thermally induced phase separation (TIPS) process to maintain a high gas [...] Read more.

The use of green solvents satisfies safer chemical engineering practices and environmental security. Herein, myristic acid (MA)—a green diluent—was selected to prepare poly- (4-methyl-1-pentene) (PMP) membranes with bicontinuous porous structure via a thermally induced phase separation (TIPS) process to maintain a high gas permeability. Firstly, based on the Hansen solubility parameter ‘distance’, Ra, the effect of four natural fatty acids on the PMP membrane structure was compared and studied to determine the optimal green diluent, MA. The thermodynamic phase diagram of the PMP-MA system was calculated and presented to show that a liquid-liquid phase separation region could be found during the TIPS process and the monotectic point was around 34.89 wt%. Then, the effect of the PMP concentration on the morphologies and crystallization behavior was systematically investigated to determine a proper PMP concentration for the membrane preparation. Finally, PMP hollow fiber (HF) membranes were fabricated with a PMP concentration of 30 wt% for the membrane performance characterization. The resultant PMP HF membranes possessed good performances that the porosity was 70%, the tensile strength was 96 cN, and the nitrogen flux was 8.20 ± 0.10 mL·(bar·cm²·min)⁻¹. We believe that this work can be a beneficial reference for people interested in the preparation of PMP membranes for medical applications. Full article

(This article belongs to the Special Issue Hollow Fiber Membranes and Their Applications)

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11 pages, 7484 KiB

Open AccessArticle

Supported MXene/GO Composite Membranes with Suppressed Swelling for Metal Ion Sieving

by Zongjie Yin, Zong Lu, Yanyan Xu, Yonghong Zhang, Liliang He, Peishan Li, Lei Xiong, Li Ding, Yanying Wei and Haihui Wang

Membranes 2021, 11(8), 621; https://doi.org/10.3390/membranes11080621 - 13 Aug 2021

Cited by 20 | Viewed by 3826

Abstract

Novel two-dimensional (2D) membranes have been utilized in water purification or seawater desalination due to their highly designable structure. However, they usually suffer from swelling problems when immersed in solution, which limits their further applications. In this study, 2D cross-linked MXene/GO composite membranes [...] Read more.

Novel two-dimensional (2D) membranes have been utilized in water purification or seawater desalination due to their highly designable structure. However, they usually suffer from swelling problems when immersed in solution, which limits their further applications. In this study, 2D cross-linked MXene/GO composite membranes supported on porous polyamide substrates are proposed to improve the antiswelling property and enhance the ion-sieving performance. Transition-metal carbide (MXene) nanosheets were intercalated into GO nanosheets, where the carboxyl groups of GO combined the neighboring hydroxyl terminal groups of MXene with the formation of -COO- bonds between GO and MXene nanosheets via the cross-linking reaction (−OH + −COOH = −COO− + H₂O) after heat treatment. The permeation rates of the metal ions (Li⁺, Na⁺, K⁺, Al³⁺) through the cross-linked MXene/GO composite membrane were 7–40 times lower than those through the pristine MXene/GO membrane. In addition, the cross-linked MXene/GO composite membrane showed excellent Na⁺ rejection performance (99.3%), which was significantly higher than that through pristine MXene/GO composite membranes (80.8%), showing improved ion exclusion performance. Such a strategy represents a new avenue to develop 2D material-derived high-performance membranes for water purification. Full article

(This article belongs to the Special Issue Novel Supported Membranes for Syngas Generation and Hydrogen Separation)

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17 pages, 5910 KiB

Open AccessArticle

Hierarchically Assembled Type I Collagen Fibres as Biomimetic Building Blocks of Biomedical Membranes

by Jie Yin, David J. Wood, Stephen J. Russell and Giuseppe Tronci

Membranes 2021, 11(8), 620; https://doi.org/10.3390/membranes11080620 - 12 Aug 2021

Cited by 5 | Viewed by 2844

Abstract

Wet spinning is an established fibre manufacturing route to realise collagen fibres with preserved triple helix architecture and cell acceptability for applications in biomedical membranes. However, resulting fibres still need to be chemically modified post-spinning to ensure material integrity in physiological media, with [...] Read more.

Wet spinning is an established fibre manufacturing route to realise collagen fibres with preserved triple helix architecture and cell acceptability for applications in biomedical membranes. However, resulting fibres still need to be chemically modified post-spinning to ensure material integrity in physiological media, with inherent risks of alteration of fibre morphology and with limited opportunities to induce fibrillogenesis following collagen fixation in the crosslinked state. To overcome this challenge, we hypothesised that a photoactive type I collagen precursor bearing either single or multiple monomers could be employed to accomplish hierarchically assembled fibres with improved processability, macroscopic properties and nanoscale organisation via sequential wet spinning and UV-curing. In-house-extracted type I rat tail collagen functionalised with both 4-vinylbenzyl chloride (4VBC) and methacrylate residues generated a full hydrogel network following solubilisation in a photoactive aqueous solution and UV exposure, whereby ~85 wt.% of material was retained following 75-day hydrolytic incubation. Wide-angle X-ray diffraction confirmed the presence of typical collagen patterns, whilst an averaged compression modulus and swelling ratio of more than 290 kPa and 1500 wt.% was recorded in the UV-cured hydrogel networks. Photoactive type I collagen precursors were subsequently wet spun into fibres, displaying the typical dichroic features of collagen and regular fibre morphology. Varying tensile modulus (E = 5 ± 1 − 11 ± 4 MPa) and swelling ratio (SR = 1880 ± 200 − 3350 ± 500 wt.%) were measured following post-spinning UV curing and equilibration with phosphate-buffered saline (PBS). Most importantly, 72-h incubation of the wet spun fibres in PBS successfully induced renaturation of collagen-like fibrils, which were fixed following UV-induced network formation. The whole process proved to be well tolerated by cells, as indicated by a spread-like cell morphology following a 48-h culture of L929 mouse fibroblasts on the extracts of UV-cured fibres. Full article

(This article belongs to the Special Issue Membrane and Membrane Bioreactors Applied to Health and Life Sciences)

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18 pages, 1734 KiB

Open AccessArticle

Skeletal Muscle Cell Growth Alters the Lipid Composition of Extracellular Vesicles

by Taylor R. Valentino, Blake D. Rule, C. Brooks Mobley, Mariana Nikolova-Karakashian and Ivan J. Vechetti

Membranes 2021, 11(8), 619; https://doi.org/10.3390/membranes11080619 - 12 Aug 2021

Cited by 7 | Viewed by 3045

Abstract

We sought to characterize the lipid profile of skeletal muscle cell-derived Extracellular Vesicles (EVs) to determine if a hypertrophic stimulus would affect the lipid composition of C2C12 myotube-derived EVs. Analyses included C2C12 murine myoblasts differentiated into myotubes and treated with Insulin-Like Growth Factor [...] Read more.

We sought to characterize the lipid profile of skeletal muscle cell-derived Extracellular Vesicles (EVs) to determine if a hypertrophic stimulus would affect the lipid composition of C2C12 myotube-derived EVs. Analyses included C2C12 murine myoblasts differentiated into myotubes and treated with Insulin-Like Growth Factor 1 (IGF-1) for 24 h to induce hypertrophic growth. EVs were isolated from cell culture media, quantified using Nanoparticle Tracking Analysis (NTA) and analyzed using Transmission Electron Microscopy (TEM). EVs were homogenized and lipids extracted for quantification by Mass Spectrometry followed by downstream lipid class enrichment and lipid chain analysis. IGF-1 treatment elicited an increase in CD63 and CD81 levels (39% and 21%) compared to the controls (16%), respectively. Analysis revealed that skeletal muscle-derived EVs are enriched in bioactive lipids that are likely selectively incorporated into EVs during hypertrophic growth. IGF-1 treatment of myotubes had a significant impact on the levels of diacylglycerol (DG) and ceramide (Cer) in secreted EVs. Specifically, the proportion of unsaturated DG was two- to three-fold higher in EVs derived from IGF-treated cells, as compared to those from control cells. The levels of saturated DG were unaffected. Selective increases were similarly seen in C16- and C24-Cer but not in other species. Levels of free sphingoid bases tended to decrease, while those of sphingosine-1-phosphate was unaffected. Our results suggest that the lipid composition and biogenesis of skeletal muscle-derived EVs, are specific and highly selective during hypertrophic growth. Full article

(This article belongs to the Special Issue Cell Membrane Vesicles)

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16 pages, 8323 KiB

Open AccessArticle

The Phase Structural Evolution and Gas Separation Performances of Cellulose Acetate/Polyimide Composite Membrane from Polymer to Carbon Stage

by Haojie Li, Shan Xu, Bingyu Zhao, Yuxiu Yu and Yaodong Liu

Membranes 2021, 11(8), 618; https://doi.org/10.3390/membranes11080618 - 12 Aug 2021

Cited by 7 | Viewed by 2672

Abstract

Blending and heat-treatment play significant roles in adjusting gas separation performances of membranes, especially for incorporating thermally labile polymers into carbon molecular sieve membranes (CMSMs). In this work, cellulose acetate (CA) is introduced into polyimide (PI) as a sacrificial phase to adjust the [...] Read more.

Blending and heat-treatment play significant roles in adjusting gas separation performances of membranes, especially for incorporating thermally labile polymers into carbon molecular sieve membranes (CMSMs). In this work, cellulose acetate (CA) is introduced into polyimide (PI) as a sacrificial phase to adjust the structure and gas separation performance from polymer to carbon. A novel result is observed that the gas permeability is reduced, even when the immiscible CA phase decomposes and forms pores after heat treatment at 350 °C. After carbonization at 600 °C, the miscible CA has changed without contribution, while the role of the immiscible CA phase has changed from original hindrance to facilitation, the composite-based CMSM at a CA content of 10 wt.% shows highest performances, a H₂ permeability of ~5300 Barrer (56% enhancement) with a similar H₂/N₂ permselectivity of 42. The structural analyses reveal that the chain interactions and phase separation behaviors between CA and PI play critical roles on membrane structures and gas diffusion, and the corresponding phase structural evolutions during heat treatment and carbonization determine gas separation properties. Full article

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15 pages, 755 KiB

Open AccessReview

New Trends, Advantages and Disadvantages in Anticoagulation and Coating Methods Used in Extracorporeal Life Support Devices

by Anne Willers, Jutta Arens, Silvia Mariani, Helena Pels, Jos G. Maessen, Tilman M. Hackeng, Roberto Lorusso and Justyna Swol

Membranes 2021, 11(8), 617; https://doi.org/10.3390/membranes11080617 - 12 Aug 2021

Cited by 30 | Viewed by 5745

Abstract

The use of extracorporeal life support (ECLS) devices has significantly increased in the last decades. Despite medical and technological advancements, a main challenge in the ECLS field remains the complex interaction between the human body, blood, and artificial materials. Indeed, blood exposure to [...] Read more.

The use of extracorporeal life support (ECLS) devices has significantly increased in the last decades. Despite medical and technological advancements, a main challenge in the ECLS field remains the complex interaction between the human body, blood, and artificial materials. Indeed, blood exposure to artificial surfaces generates an unbalanced activation of the coagulation cascade, leading to hemorrhagic and thrombotic events. Over time, several anticoagulation and coatings methods have been introduced to address this problem. This narrative review summarizes trends, advantages, and disadvantages of anticoagulation and coating methods used in the ECLS field. Evidence was collected through a PubMed search and reference scanning. A group of experts was convened to openly discuss the retrieved references. Clinical practice in ECLS is still based on the large use of unfractionated heparin and, as an alternative in case of contraindications, nafamostat mesilate, bivalirudin, and argatroban. Other anticoagulation methods are under investigation, but none is about to enter the clinical routine. From an engineering point of view, material modifications have focused on commercially available biomimetic and biopassive surfaces and on the development of endothelialized surfaces. Biocompatible and bio-hybrid materials not requiring combined systemic anticoagulation should be the future goal, but intense efforts are still required to fulfill this purpose. Full article

(This article belongs to the Special Issue Challenges in the Extracorporeal Membrane Oxygenation Era)

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21 pages, 7221 KiB

Open AccessReview

Economics and Energy Consumption of Brackish Water Reverse Osmosis Desalination: Innovations and Impacts of Feedwater Quality

by Jeffrey L. Pearson, Peter R. Michael, Noreddine Ghaffour and Thomas M. Missimer

Membranes 2021, 11(8), 616; https://doi.org/10.3390/membranes11080616 - 12 Aug 2021

Cited by 24 | Viewed by 5048

Abstract

Brackish water desalination, using the reverse osmosis (BWRO) process, has become common in global regions, where vast reserves of brackish groundwater are found (e.g., the United States, North Africa). A literature survey and detailed analyses of several BWRO facilities in Florida have revealed [...] Read more.

Brackish water desalination, using the reverse osmosis (BWRO) process, has become common in global regions, where vast reserves of brackish groundwater are found (e.g., the United States, North Africa). A literature survey and detailed analyses of several BWRO facilities in Florida have revealed some interesting and valuable information on the costs and energy use. Depending on the capacity, water quality, and additional scope items, the capital cost (CAPEX) ranges from USD 500 to USD 2947/m³ of the capacity (USD 690–USD 4067/m³ corrected for inflation to 2020). The highest number was associated with the City of Cape Coral North Plant, Florida, which had an expanded project scope. The general range of the operating cost (OPEX) is USD 0.39 to USD 0.66/m³ (cannot be corrected for inflation), for a range of capacities from 10,000 to 70,000 m³/d. The feed-water quality, in the range of 2000 to 6000 mg/L of the total dissolved solids, does not significantly impact the OPEX. There is a significant scaling trend, with OPEX cost reducing as plant capacity increases, but there is considerable scatter based on the pre- and post-treatment complexity. Many BWRO facilities operate with long-term increases in the salinity of the feedwater (groundwater), caused by pumping-induced vertical and horizontal migration of the higher salinity water. Any cost and energy increase that is caused by the higher feed water salinity, can be significantly mitigated by using energy recovery, which is not commonly used in BWRO operations. OPEX in BWRO systems is likely to remain relatively constant, based on the limitation on the plant capacity, caused by the brackish water availability at a given site. Seawater reverse osmosis facilities, with a very large capacity, have a lower OPEX compared to the upper range of BWRO, because of capacity scaling, special electrical energy deals, and process design certainty. Full article

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