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Membranes
Volume 11
Issue 3
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Membranes, Volume 11, Issue 3 (March 2021) – 72 articles

Cover Story (view full-size image): The organic solvent nanofiltration (OSN) membrane process has been recognized as a green separation technology with low energy consumption and mild operation conditions. To effectively separate solutes from organic solvent phase, it is fundamental to design membrane structures and materials and to control the physico-chemical properties of the membranes involved. The aim of this review is to understand the promising candidate materials for high-permeable thin film composite (TFC) membranes against non-polar solvents. In particular, the well-designed selective layer of TFC membranes is required for enhancing the solubility and permeability of non-polar solvents, which could lead to the application expansion of the OSN membrane process in both academic and industrial fields. View this paper.
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13 pages, 11554 KiB  
Article
Pervaporative Dehydration of Organic Solvents Using High-Silica CHA-Type Zeolite Membrane
by Yasuhisa Hasegawa, Chie Abe and Ayumi Ikeda
Membranes 2021, 11(3), 229; https://doi.org/10.3390/membranes11030229 - 23 Mar 2021
Cited by 27 | Viewed by 3884
Abstract
A high-silica chabazite (CHA) type zeolite membrane was prepared on the porous α-Al2O3 support tube by the secondary growth of seed particles. The dehydration performances of the membrane were determined using methanol, ethanol, 2-propanol, acetone, acetic acid, methyl ethyl ketone [...] Read more.
A high-silica chabazite (CHA) type zeolite membrane was prepared on the porous α-Al2O3 support tube by the secondary growth of seed particles. The dehydration performances of the membrane were determined using methanol, ethanol, 2-propanol, acetone, acetic acid, methyl ethyl ketone (MEK), tetrahydrofuran (THF), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and N-methyl-2-pyrolidone (NMP) at 303–373 K. As a result, the dehydration performances of the membrane were categorized to following three types: (1) 2-propanol, acetone, THF, and MEK; (2) ethanol and acetic acid; and (3) methanol, DMF, and DMSO, and NMP. The adsorption isotherms of water, methanol, ethanol, and 2-propanol were determined to discuss the influences of the organic solvents on the permeation and separation performances of the membrane. For 2-propanol, acetone, MEK, and THF solutions, the high permeation fluxes and separation factors were obtained because of the preferential adsorption of water due to molecular sieving. In contrast, the permeation fluxes and separation factors were relatively low for methanol, DMF, and DMSO, and NMP solutions. The lower dehydration performance for the methanol solution was due to the adsorption of methanol. The permeation fluxes for ethanol and acetic acid solution were ca. 1 kg m−2 h−1. The significantly low flux was attributed to the similar molecular diameter to the micropore size of CHA-type zeolite. Full article
(This article belongs to the Special Issue Zeolite Membrane: From Microstructure to Separation Performance)
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19 pages, 8016 KiB  
Article
Carnauba Wax/Halloysite Nanotube with Improved Anti-Wetting and Permeability of Hydrophobic PVDF Membrane via DCMD
by Wan Aisyah Fadilah Wae AbdulKadir, Abdul Latif Ahmad and Ooi Boon Seng
Membranes 2021, 11(3), 228; https://doi.org/10.3390/membranes11030228 - 23 Mar 2021
Cited by 7 | Viewed by 3488
Abstract
The hydrophobic membranes have been widely explored to meet the membrane characteristics for the membrane distillation (MD) process. Inorganic metal oxide nanoparticles have been used to improve the membrane hydrophobicity, but limited studies have used nano clay particles. This study introduces halloysite nanotube [...] Read more.
The hydrophobic membranes have been widely explored to meet the membrane characteristics for the membrane distillation (MD) process. Inorganic metal oxide nanoparticles have been used to improve the membrane hydrophobicity, but limited studies have used nano clay particles. This study introduces halloysite nanotube (HNT) as an alternative material to synthesis a hydrophobic poly(vinylidene fluoride) (PVDF)-HNT membrane. The PVDF membranes were fabricated using functionalized HNTs (e.g., carnauba wax and 1H,1H,2H,2H-perfluorooctyl-trichlorosilane (FOTS)). The results were determined by Fourier transform infrared-attenuated total reflection, scanning electron microscope, goniometer and porometer to determine the desired hydrophobic membrane for direct contact membrane distillation (DCMD). The addition of FOTS-HNT (fs-HNT) and carnauba wax-HNT (fw-HNT) in the PVDF membrane enhanced the water contact angle (CA) to 127° and 137°, respectively. The presence of fw-HNT in the PVDF membrane exhibited higher liquid entry pressure (LEP) (2.64 bar) compared to fs-HNT in the membrane matrix (1.44 bar). The PVDF/fw-HNT membrane (Pfw-HNT) obtained the highest flux of 7.24 L/m2h with 99.9% salt removal. A stable permeability in the Pfw-HNT membrane was obtained throughout 16 h of DCMD. The incorporation of fw-HNT in the PVDF membrane had improved the anti-wetting properties and the membrane performance with the anti-fouling effect. Full article
(This article belongs to the Section Membrane Applications)
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19 pages, 6433 KiB  
Article
Permselectivity of Cation Exchange Membranes Modified by Polyaniline
by Irina Falina, Natalia Loza, Sergey Loza, Ekaterina Titskaya and Nazar Romanyuk
Membranes 2021, 11(3), 227; https://doi.org/10.3390/membranes11030227 - 23 Mar 2021
Cited by 35 | Viewed by 3947
Abstract
This work discusses the applicability of polyaniline-modified cation exchange membranes for the separation of monovalent/divalent cations by electrodialysis. A novel method of membrane modification directly in the electrodialysis unit is used to prepare permselective membranes. Complex characterization of the membranes before and after [...] Read more.
This work discusses the applicability of polyaniline-modified cation exchange membranes for the separation of monovalent/divalent cations by electrodialysis. A novel method of membrane modification directly in the electrodialysis unit is used to prepare permselective membranes. Complex characterization of the membranes before and after modification allows revealing the influence of membrane matrix on the modification efficiency. The characterization of the membranes includes determination of the diffusion permeability, specific conductivity and current–voltage curves in HCl, NaCl and CaCl2 solutions, as well as transport-structural parameters of the extended three-wire model. The characterization results are used to predict the influence of the modification on membrane permselectivity. The competitive mass transfer of singly and doubly charged cations in the electrodialysis process is investigated in underlimiting and overlimiting currents. Electrodialysis desalination of a solution containing Na+/Ca2+ or H+/Ca2+ cations shows that the modification leads to an increase in membrane permselectivity to single-charged cations due to the repulsion of Ca2+ ions from the positively charged membrane surface. The permselectivity of the polyaniline-modified perfluorinated membrane to H+ in the mixture of H+/Ca2+ cations is observed in all current regimes. Full article
(This article belongs to the Special Issue Ion-Exchange Membranes and Processes (Volume II))
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14 pages, 4124 KiB  
Article
Coupling of Immobilized Photosynthetic Bacteria with a Graphene Oxides/PSF Composite Membrane for Textile Wastewater Treatment: Biodegradation Performance and Membrane Anti-Fouling Behavior
by Jing Cheng, Xiaofeng Wu, Binbin Jin, Chenchen Zhang, Rongwei Zheng and Lei Qin
Membranes 2021, 11(3), 226; https://doi.org/10.3390/membranes11030226 - 22 Mar 2021
Cited by 11 | Viewed by 2823
Abstract
The membrane bioreactor (MBR), as one of the promising technologies, has been widely applied for treatments of wastewater. However, serious membrane fouling and low microbial activity have been reported as major problems hindering the development of the MBR. To overcome these drawbacks, we [...] Read more.
The membrane bioreactor (MBR), as one of the promising technologies, has been widely applied for treatments of wastewater. However, serious membrane fouling and low microbial activity have been reported as major problems hindering the development of the MBR. To overcome these drawbacks, we intend to improve the MBR process in the view of membrane surface modification and efficient granular bacteria cultivation. In the present study, immobilized photosynthetic bacteria integration with graphene oxide (GO)/polysulfone (PSF) composite membrane separation (IPMBR) was first applied for textile wastewater treatment. Due to the high activity of immobilized cells, the IPMBR system exhibited higher efficiency on the removal of color, ammonia–nitrogen, and chemical oxygen demand than the conventional MBR system. In comparison with a pure PSF membrane, GO/PSF composite membrane presented the higher hydrophilicity (water contact angles of 62.9°) and more attractive permeability (178.5 L/m2h) by reducing the adhesion of hydrophobic foulants. During the whole operation, the immobilized photobioreactor exhibited approximately seven times higher membrane permeability that that of the conventional MBR. Meanwhile, the effect of the structure and character of immobilized photosynthetic bacteria on the membrane fouling reduction was investigated in detail. The change of extracellular polymeric substance concentration, settleability and particle size of flocs was very beneficial to alleviate membrane fouling. As a result, this research will open a new avenue for developing efficient and anti-fouling MBR technology in the future. Full article
(This article belongs to the Special Issue Modelling, Optimization and Applications of Membrane Bioreactors for Resource Recovery)
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17 pages, 1838 KiB  
Review
Physiological Basis of Extracorporeal Membrane Oxygenation and Extracorporeal Carbon Dioxide Removal in Respiratory Failure
by Barbara Ficial, Francesco Vasques, Joe Zhang, Stephen Whebell, Michael Slattery, Tomas Lamas, Kathleen Daly, Nicola Agnew and Luigi Camporota
Membranes 2021, 11(3), 225; https://doi.org/10.3390/membranes11030225 - 22 Mar 2021
Cited by 24 | Viewed by 10466
Abstract
Extracorporeal life support (ECLS) for severe respiratory failure has seen an exponential growth in recent years. Extracorporeal membrane oxygenation (ECMO) and extracorporeal CO2 removal (ECCO2R) represent two modalities that can provide full or partial support of the native lung function, [...] Read more.
Extracorporeal life support (ECLS) for severe respiratory failure has seen an exponential growth in recent years. Extracorporeal membrane oxygenation (ECMO) and extracorporeal CO2 removal (ECCO2R) represent two modalities that can provide full or partial support of the native lung function, when mechanical ventilation is either unable to achieve sufficient gas exchange to meet metabolic demands, or when its intensity is considered injurious. While the use of ECMO has defined indications in clinical practice, ECCO2R remains a promising technique, whose safety and efficacy are still being investigated. Understanding the physiological principles of gas exchange during respiratory ECLS and the interactions with native gas exchange and haemodynamics are essential for the safe applications of these techniques in clinical practice. In this review, we will present the physiological basis of gas exchange in ECMO and ECCO2R, and the implications of their interaction with native lung function. We will also discuss the rationale for their use in clinical practice, their current advances, and future directions. Full article
(This article belongs to the Special Issue Advances in Extracorporeal Membrane Oxygenation)
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13 pages, 2460 KiB  
Article
Composite Polymer Anion Exchange Membranes with Sandwich Structure and Improved Performance for Zn–Air Battery
by Xiaoxia Cai, Yuansong Zhang, Cong Li, Guotao Zhang, Xiaotao Wang, Xian Zhang, Qiang Wang and Fuzhong Wang
Membranes 2021, 11(3), 224; https://doi.org/10.3390/membranes11030224 - 22 Mar 2021
Cited by 8 | Viewed by 2656
Abstract
In this study, we fabricated a composite polymer anion exchange membrane (AEM) with a sandwich structure. This prepared AEM demonstrated high ionic conductivity (0.25 Scm−1), excellent alkali resistance (8 M KOH), and good mechanical properties (tensile strength of 0.455 MPa and [...] Read more.
In this study, we fabricated a composite polymer anion exchange membrane (AEM) with a sandwich structure. This prepared AEM demonstrated high ionic conductivity (0.25 Scm−1), excellent alkali resistance (8 M KOH), and good mechanical properties (tensile strength of 0.455 MPa and elongation at break of 82.13%). Here, degrease cotton (DC) treated with LiOH/urea aqueous solution was used and immersed into a coagulation bath to form a film. This film was immersed in acrylic acid (AA) monomers, and in-suit polymerization was carried out in the presence of KOH and an initiator. Finally, a composite polymer membrane with sandwich structure was achieved, in which the upper and bottom layers were mainly composed of polymerized AA (PAA) while the central layer was mainly composed of DC derived film. The central layer acted as a skeleton to improve the mechanical properties and alkali resistance. The top and bottom layers (PAA-rich layers) acted as OH- ion transport carriers, making basic cations migrate along the main chain of PAA. This newly developed composite membrane showed increased tensile strength and an elongation at break of 2.7 and 1.5 times, respectively, when compared to a control PAA/KOH AEM film. Furthermore, an electrochemical stability window of 2.0 V was measured via the cyclic voltammetry curve test, showing a wide electrochemical window and promising application in Zn–Air batteries. Full article
(This article belongs to the Special Issue Flexible Membranes for Batteries and Supercapacitor Applications)
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18 pages, 3674 KiB  
Article
Electrodeposited Hybrid Biocathode-Based CO2 Reduction via Microbial Electro-Catalysis to Biofuels
by Abdul Hakeem Anwer, Nishat Khan, Mohammad Faisal Umar, Mohd Rafatullah and Mohammad Zain Khan
Membranes 2021, 11(3), 223; https://doi.org/10.3390/membranes11030223 - 22 Mar 2021
Cited by 10 | Viewed by 3090
Abstract
Microbial electrosynthesis is a new approach to converting C1 carbon (CO2) to more complex carbon-based products. In the present study, CO2, a potential greenhouse gas, was used as a sole carbon source and reduced to value-added chemicals (acetate, ethanol) [...] Read more.
Microbial electrosynthesis is a new approach to converting C1 carbon (CO2) to more complex carbon-based products. In the present study, CO2, a potential greenhouse gas, was used as a sole carbon source and reduced to value-added chemicals (acetate, ethanol) with the help of bioelectrochemical reduction in microbial electrosynthesis systems (MES). The performance of MES was studied with varying electrode materials (carbon felt, stainless steel, and cobalt electrodeposited carbon felt). The MES performance was assessed in terms of acetic acid and ethanol production with the help of gas chromatography (GC). The electrochemical characterization of the system was analyzed with chronoamperometry and cyclic voltammetry. The study revealed that the MES operated with hybrid cobalt electrodeposited carbon felt electrode yielded the highest acetic acid (4.4 g/L) concentration followed by carbon felt/stainless steel (3.7 g/L), plain carbon felt (2.2 g/L), and stainless steel (1.87 g/L). The alcohol concentration was also observed to be highest for the hybrid electrode (carbon felt/stainless steel/cobalt oxide is 0.352 g/L) as compared to the bare electrodes (carbon felt is 0.22 g/L) tested, which was found to be in correspondence with the pH changes in the system. Electrochemical analysis revealed improved electrotrophy in the hybrid electrode, as confirmed by the increased redox current for the hybrid electrode as compared to plain electrodes. Cyclic voltammetry analysis also confirmed the role of the biocatalyst developed on the electrode in CO2 sequestration. Full article
(This article belongs to the Section Membrane Applications)
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21 pages, 903 KiB  
Review
Every Detail Matters. That Is, How the Interaction between Gα Proteins and Membrane Affects Their Function
by Agnieszka Polit, Paweł Mystek and Ewa Błasiak
Membranes 2021, 11(3), 222; https://doi.org/10.3390/membranes11030222 - 20 Mar 2021
Cited by 4 | Viewed by 3195
Abstract
In highly organized multicellular organisms such as humans, the functions of an individual cell are dependent on signal transduction through G protein-coupled receptors (GPCRs) and subsequently heterotrimeric G proteins. As most of the elements belonging to the signal transduction system are bound to [...] Read more.
In highly organized multicellular organisms such as humans, the functions of an individual cell are dependent on signal transduction through G protein-coupled receptors (GPCRs) and subsequently heterotrimeric G proteins. As most of the elements belonging to the signal transduction system are bound to lipid membranes, researchers are showing increasing interest in studying the accompanying protein–lipid interactions, which have been demonstrated to not only provide the environment but also regulate proper and efficient signal transduction. The mode of interaction between the cell membrane and G proteins is well known. Despite this, the recognition mechanisms at the molecular level and how the individual G protein-membrane attachment signals are interrelated in the process of the complex control of membrane targeting of G proteins remain unelucidated. This review focuses on the mechanisms by which mammalian Gα subunits of G proteins interact with lipids and the factors responsible for the specificity of membrane association. We summarize recent data on how these signaling proteins are precisely targeted to a specific site in the membrane region by introducing well-defined modifications as well as through the presence of polybasic regions within these proteins and interactions with other components of the heterocomplex. Full article
(This article belongs to the Special Issue Membrane Domains Organization and Interactions)
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18 pages, 1876 KiB  
Article
Ultrafiltration Process in Disinfection and Advanced Treatment of Tertiary Treated Wastewater
by Rafał Tytus Bray, Katarzyna Jankowska, Eliza Kulbat, Aneta Łuczkiewicz and Aleksandra Sokołowska
Membranes 2021, 11(3), 221; https://doi.org/10.3390/membranes11030221 - 20 Mar 2021
Cited by 19 | Viewed by 3708
Abstract
The paper presents the results of research on the use of ultrafiltration, using membranes of 200 and 400 kDa separation, for disinfection of municipal treated wastewater. The research was conducted on a fractional technical scale using real municipal treated wastewater from two large [...] Read more.
The paper presents the results of research on the use of ultrafiltration, using membranes of 200 and 400 kDa separation, for disinfection of municipal treated wastewater. The research was conducted on a fractional technical scale using real municipal treated wastewater from two large wastewater treatment plants treating most of the wastewater over the one-million polycentric Gdańsk agglomeration (1.2 million inhabitants). UF 200 kDa and UF 400 kDa processes enabled further improvement of the physical and chemical parameters of treated wastewater. Total phosphorus (to below 0.2 mg/L–UF 200 kDa, 0.13 mg/L–UF 400 kDa) and turbid substances (to below 0.2 mg/L, both membranes) were removed in the highest degree. COD was reduced efficiently (to below 25.6 mgO2/L–UF 200 kDa, 26.8 mgO2/L–UF 400 kDa), while total nitrogen was removed to a small extent (to 7.12 mg/L–UF 200 kDa and 5.7 mg/L–UF 400 kDa. Based on the reduction of indicator bacteria; fecal coliforms including E. coli (FC) and fecal enterococci (FE) it was found that the ultrafiltration is an effective method of disinfection. Not much indicator bacterial were observed in the permeate after processes (UF 200 kDa; FC—5 CFU/L; FE—1 CFU/L and UF 400 kDa; FC—70 CFU/L; FE—10 CFU/L. However, microscopic analysis of prokaryotic cells and virus particles showed their presence after the application of both membrane types; TCN 3.0 × 102 cells/mL–UF 200 kDa, 5.0 × 103 cells/mL–UF 400 kDa, VP 1.0 × 105/mL. The presence of potentially pathogenic, highly infectious virus particles means that ultrafiltration cannot be considered a sufficient disinfection method for treated wastewater diverted for reuse or discharged from high load wastewater treatment plants to recreational areas. For full microbiological safety it would be advisable to apply an additional disinfection method (e.g., ozonation). Full article
(This article belongs to the Special Issue Membranes for Water Disinfection)
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31 pages, 3109 KiB  
Article
Theoretical Analysis of a Mathematical Relation between Driving Pressures in Membrane-Based Desalting Processes
by Sung Ho Chae and Joon Ha Kim
Membranes 2021, 11(3), 220; https://doi.org/10.3390/membranes11030220 - 19 Mar 2021
Cited by 3 | Viewed by 2343
Abstract
Osmotic and hydraulic pressures are both indispensable for operating membrane-based desalting processes, such as forward osmosis (FO), pressure-retarded osmosis (PRO), and reverse osmosis (RO). However, a clear relation between these driving pressures has not thus far been identified; hence, the effect of change [...] Read more.
Osmotic and hydraulic pressures are both indispensable for operating membrane-based desalting processes, such as forward osmosis (FO), pressure-retarded osmosis (PRO), and reverse osmosis (RO). However, a clear relation between these driving pressures has not thus far been identified; hence, the effect of change in driving pressures on systems has not yet been sufficiently analyzed. In this context, this study formulates an actual mathematical relation between the driving pressures of membrane-based desalting processes by taking into consideration the presence of energy loss in each driving pressure. To do so, this study defines the pseudo-driving pressures representing the water transport direction of a system and the similarity coefficients that quantify the energy conservation rule. Consequently, this study finds three other theoretical constraints that are required to operate membrane-based desalting processes. Furthermore, along with the features of the similarity coefficients, this study diagnoses the commercial advantage of RO over FO/PRO and suggests desirable optimization sequences applicable to each process. Since this study provides researchers with guidelines regarding optimization sequences between membrane parameters and operational parameters for membrane-based desalting processes, it is expected that detailed optimization strategies for the processes could be established. Full article
(This article belongs to the Special Issue Numerical Modelling in Membrane Processes)
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10 pages, 3360 KiB  
Article
A Gel Polymer Electrolyte Reinforced Membrane for Lithium-Ion Batteries via the Simultaneous-Irradiation of the Electron Beam
by Jian Hou, In Kee Park, Woo Ju Cha and Chang Hyun Lee
Membranes 2021, 11(3), 219; https://doi.org/10.3390/membranes11030219 - 19 Mar 2021
Cited by 7 | Viewed by 3684
Abstract
In this research, a series of innovative and stable cross-linked gel polymer reinforced membranes (GPRMs), were successfully prepared and investigated for application in lithium-ion batteries. Herein, a gel directly within the commercial polyethylene (PE) separator is supported via electron-beam simultaneous irradiation cross-linking of [...] Read more.
In this research, a series of innovative and stable cross-linked gel polymer reinforced membranes (GPRMs), were successfully prepared and investigated for application in lithium-ion batteries. Herein, a gel directly within the commercial polyethylene (PE) separator is supported via electron-beam simultaneous irradiation cross-linking of commercial liquid electrolyte and poly(ethylene glycol) methacrylate (PEGMA) oligomers. The physical and electrochemical properties of the GPRMs were characterized by SEM, TEM, mechanical durability, heating shrinkage, and ion conductivity, etc. The GPRMs demonstrated excellent mechanical durability and high ion conductivity compared with traditional PE membranes. Moreover, coin-typed cells were assembled and cycle performance was also studied compared with same-typed cells with commercial PE membrane and liquid electrolyte. As a result, the coin-typed cells using GPRMs also showed a relatively good efficiency on the 50th cycles at a high 1.0 C-rate. These GPRMs with excellent properties present a very promising material for utilization in high-performance lithium-ion batteries with improved safety and reliability. Full article
(This article belongs to the Special Issue Polymer Membranes and beyond for Sustainable Separations: From Synthesis, Characterization to Applications)
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16 pages, 5247 KiB  
Article
The Missing Protein: Is T-Cadherin a Previously Unknown GPI-Anchored Receptor on Platelets?
by Maria N. Balatskaya, Alexandra I. Baglay and Alexander V. Balatskiy
Membranes 2021, 11(3), 218; https://doi.org/10.3390/membranes11030218 - 19 Mar 2021
Cited by 2 | Viewed by 2720
Abstract
The membrane of platelets contains at least one uncharacterized glycosylphosphatidylinositol (GPI)-anchored protein according to the literature. Moreover, there is not enough knowledge on the receptor of low-density lipoproteins (LDL) mediating rapid Ca2+ signaling in platelets. Coincidentally, expression of a GPI-anchored protein T-cadherin [...] Read more.
The membrane of platelets contains at least one uncharacterized glycosylphosphatidylinositol (GPI)-anchored protein according to the literature. Moreover, there is not enough knowledge on the receptor of low-density lipoproteins (LDL) mediating rapid Ca2+ signaling in platelets. Coincidentally, expression of a GPI-anchored protein T-cadherin increases LDL-induced Ca2+ signaling in nucleated cells. Here we showed evidence that supports the hypothesis about the presence of T-cadherin on platelets. The presence of T-cadherin on the surface of platelets and megakaryocytes was proven using antibodies whose specificity was tested on several negative and positive control cells by flow cytometry and confocal microscopy. Using phosphatidylinositol-specific phospholipase C, the presence of glycosylphosphatidylinositol anchor in the platelet T-cadherin form as well as in other known forms was confirmed. We showed by immunoblotting that the significant part of T-cadherin was detected in specific membrane domains (detergent Triton X-114 resistant) and the molecular weight of this newly identified protein was greater than that of T-cadherin from nucleated cells. Nevertheless, polymerase chain reaction data confirmed only the presence of isoform-1 of T-cadherin in platelets and megakaryocytes, which was also present in nucleated cells. We observed the redistribution of this newly identified protein after the activation of platelets, but only further work may explain its functional importance. Thus, our data described T-cadherin with some post-translational modifications as a new GPI-anchored protein on human platelets. Full article
(This article belongs to the Special Issue Biomolecules in Cell Membranes: Structure and Dynamics)
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17 pages, 3300 KiB  
Article
Evaluation of Electrodialysis Desalination Performance of Novel Bioinspired and Conventional Ion Exchange Membranes with Sodium Chloride Feed Solutions
by AHM Golam Hyder, Brian A. Morales, Malynda A. Cappelle, Stephen J. Percival, Leo J. Small, Erik D. Spoerke, Susan B. Rempe and W. Shane Walker
Membranes 2021, 11(3), 217; https://doi.org/10.3390/membranes11030217 - 19 Mar 2021
Cited by 14 | Viewed by 5652
Abstract
Electrodialysis (ED) desalination performance of different conventional and laboratory-scale ion exchange membranes (IEMs) has been evaluated by many researchers, but most of these studies used their own sets of experimental parameters such as feed solution compositions and concentrations, superficial velocities of the process [...] Read more.
Electrodialysis (ED) desalination performance of different conventional and laboratory-scale ion exchange membranes (IEMs) has been evaluated by many researchers, but most of these studies used their own sets of experimental parameters such as feed solution compositions and concentrations, superficial velocities of the process streams (diluate, concentrate, and electrode rinse), applied electrical voltages, and types of IEMs. Thus, direct comparison of ED desalination performance of different IEMs is virtually impossible. While the use of different conventional IEMs in ED has been reported, the use of bioinspired ion exchange membrane has not been reported yet. The goal of this study was to evaluate the ED desalination performance differences between novel laboratory‑scale bioinspired IEM and conventional IEMs by determining (i) limiting current density, (ii) current density, (iii) current efficiency, (iv) salinity reduction in diluate stream, (v) normalized specific energy consumption, and (vi) water flux by osmosis as a function of (a) initial concentration of NaCl feed solution (diluate and concentrate streams), (b) superficial velocity of feed solution, and (c) applied stack voltage per cell-pair of membranes. A laboratory‑scale single stage batch-recycle electrodialysis experimental apparatus was assembled with five cell‑pairs of IEMs with an active cross-sectional area of 7.84 cm2. In this study, seven combinations of IEMs (commercial and laboratory-made) were compared: (i) Neosepta AMX/CMX, (ii) PCA PCSA/PCSK, (iii) Fujifilm Type 1 AEM/CEM, (iv) SUEZ AR204SZRA/CR67HMR, (v) Ralex AMH-PES/CMH-PES, (vi) Neosepta AMX/Bare Polycarbonate membrane (Polycarb), and (vii) Neosepta AMX/Sandia novel bioinspired cation exchange membrane (SandiaCEM). ED desalination performance with the Sandia novel bioinspired cation exchange membrane (SandiaCEM) was found to be competitive with commercial Neosepta CMX cation exchange membrane. Full article
(This article belongs to the Special Issue Ion-Exchange Membranes: From Synthesis to Applications)
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16 pages, 3975 KiB  
Article
Infusion of Silver–Polydopamine Particles into Polyethersulfone Matrix to Improve the Membrane’s Dye Desalination Performance and Antibacterial Property
by Hazel Lynn C. Maganto, Micah Belle Marie Yap Ang, Gian Vincent C. Dizon, Alvin R. Caparanga, Ruth R. Aquino, Shu-Hsien Huang, Hui-An Tsai and Kueir-Rarn Lee
Membranes 2021, 11(3), 216; https://doi.org/10.3390/membranes11030216 - 19 Mar 2021
Cited by 9 | Viewed by 3199
Abstract
The advancement in membrane science and technology, particularly in nanofiltration applications, involves the blending of functional nanocomposites into the membranes to improve the membrane property. In this study, Ag-polydopamine (Ag-PDA) particles were synthesized through in situ PDA-mediated reduction of AgNO3 to silver. [...] Read more.
The advancement in membrane science and technology, particularly in nanofiltration applications, involves the blending of functional nanocomposites into the membranes to improve the membrane property. In this study, Ag-polydopamine (Ag-PDA) particles were synthesized through in situ PDA-mediated reduction of AgNO3 to silver. Infusing Ag-PDA particles into polyethersulfone (PES) matrix affects the membrane property and performance. X-ray photoelectron spectroscopy (XPS) analyses confirmed the presence of Ag-PDA particles on the membrane surface. Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) describe the morphology of the membranes. At an optimum concentration of Ag-PDA particles (0.3 wt % based on the concentration of PES), the modified membrane exhibited high water flux 13.33 L∙m−2∙h−1 at 4 bar with high rejection for various dyes of >99%. The PESAg-PDA0.3 membrane had a pure water flux more than 5.4 times higher than that of a pristine membrane. Furthermore, in bacterial attachment using Escherichia coli, the modified membrane displayed less bacterial attachment compared with the pristine membrane. Therefore, immobilizing Ag-PDA particles into the PES matrix enhanced the membrane performance and antibacterial property. Full article
(This article belongs to the Special Issue Nanostructured Membranes II)
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4 pages, 193 KiB  
Editorial
Enhancing the Efficiency of Membrane Processes for Water Treatment
by Ibrahim M.A. ElSherbiny and Stefan Panglisch
Membranes 2021, 11(3), 215; https://doi.org/10.3390/membranes11030215 - 19 Mar 2021
Cited by 4 | Viewed by 3015
Abstract
Pressure-driven membrane processes, i [...] Full article
(This article belongs to the Special Issue Enhancing the Efficiency of Membrane Processes for Water Treatment)
54 pages, 12920 KiB  
Review
Polymer Membranes for All-Vanadium Redox Flow Batteries: A Review
by Dennis Düerkop, Hartmut Widdecke, Carsten Schilde, Ulrich Kunz and Achim Schmiemann
Membranes 2021, 11(3), 214; https://doi.org/10.3390/membranes11030214 - 18 Mar 2021
Cited by 47 | Viewed by 10763
Abstract
Redox flow batteries such as the all-vanadium redox flow battery (VRFB) are a technical solution for storing fluctuating renewable energies on a large scale. The optimization of cells regarding performance, cycle stability as well as cost reduction are the main areas of research [...] Read more.
Redox flow batteries such as the all-vanadium redox flow battery (VRFB) are a technical solution for storing fluctuating renewable energies on a large scale. The optimization of cells regarding performance, cycle stability as well as cost reduction are the main areas of research which aim to enable more environmentally friendly energy conversion, especially for stationary applications. As a critical component of the electrochemical cell, the membrane influences battery performance, cycle stability, initial investment and maintenance costs. This review provides an overview about flow-battery targeted membranes in the past years (1995–2020). More than 200 membrane samples are sorted into fluoro-carbons, hydro-carbons or N-heterocycles according to the basic polymer used. Furthermore, the common description in membrane technology regarding the membrane structure is applied, whereby the samples are categorized as dense homogeneous, dense heterogeneous, symmetrical or asymmetrically porous. Moreover, these properties as well as the efficiencies achieved from VRFB cycling tests are discussed, e.g., membrane samples of fluoro-carbons, hydro-carbons and N-heterocycles as a function of current density. Membrane properties taken into consideration include membrane thickness, ion-exchange capacity, water uptake and vanadium-ion diffusion. The data on cycle stability and costs of commercial membranes, as well as membrane developments, are compared. Overall, this investigation shows that dense anion-exchange membranes (AEM) and N-heterocycle-based membranes, especially poly(benzimidazole) (PBI) membranes, are suitable for VRFB requiring low self-discharge. Symmetric and asymmetric porous membranes, as well as cation-exchange membranes (CEM) enable VRFB operation at high current densities. Amphoteric ion-exchange membranes (AIEM) and dense heterogeneous CEM are the choice for operation mode with the highest energy efficiency. Full article
(This article belongs to the Special Issue Membrane Surface Modification and Functionalization)
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16 pages, 6706 KiB  
Article
Antifouling and Flux Enhancement of Reverse Osmosis Membrane by Grafting Poly (3-Sulfopropyl Methacrylate) Brushes
by Reema Mushtaq, Muhammad Asad Abbas, Shehla Mushtaq, Nasir M. Ahmad, Niaz Ali Khan, Asad U. Khan, Wu Hong, Rehan Sadiq and Zhongyi Jiang
Membranes 2021, 11(3), 213; https://doi.org/10.3390/membranes11030213 - 18 Mar 2021
Cited by 15 | Viewed by 3856
Abstract
A commercial thin film composite (TFC) polyamide (PA) reverse osmosis membrane was grafted with 3-sulfopropyl methacrylate potassium (SPMK) to produce PA-g-SPMK by atom transfer radical polymerization (ATRP). The grafting of PA was done at varied concentrations of SPMK, and its effect on the [...] Read more.
A commercial thin film composite (TFC) polyamide (PA) reverse osmosis membrane was grafted with 3-sulfopropyl methacrylate potassium (SPMK) to produce PA-g-SPMK by atom transfer radical polymerization (ATRP). The grafting of PA was done at varied concentrations of SPMK, and its effect on the surface composition and morphology was studied by Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), optical profilometry, and contact angle analysis. The grafting of hydrophilic ionically charged PSPMK polymer brushes having acrylate and sulfonate groups resulted in enhanced hydrophilicity rendering a reduction of contact angle from 58° of pristine membrane sample labeled as MH0 to 10° for a modified membrane sample labeled as MH3. Due to the increased hydrophilicity, the flux rate rises from 57.1 L m−2 h−1 to 71.2 L m−2 h−1, and 99% resistance against microbial adhesion (Escherichia coli and Staphylococcus aureus) was obtained for MH3 after modification Full article
(This article belongs to the Section Membrane Chemistry)
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16 pages, 1671 KiB  
Article
Nanofiltration Process for Enhanced Treatment of RO Brine Discharge
by Mohamed E.A. Ali
Membranes 2021, 11(3), 212; https://doi.org/10.3390/membranes11030212 - 18 Mar 2021
Cited by 35 | Viewed by 4286
Abstract
Brine discharge of reverse osmosis (RO) desalination plants represents a challenge for both inland and coastal desalination plants. Zero-liquid discharge (ZLD) can be accomplished by using additional stages of RO, which can recycle that brine water, but the key challenge is the high [...] Read more.
Brine discharge of reverse osmosis (RO) desalination plants represents a challenge for both inland and coastal desalination plants. Zero-liquid discharge (ZLD) can be accomplished by using additional stages of RO, which can recycle that brine water, but the key challenge is the high concentration of divalent salts. These divalent salts (especially calcium and magnesium salts) forms a scaling layer on the RO membrane surfaces and hence shorten the life-time of the membranes. In this study, the nanofiltration (NF) procedure was used to remove divalent ions from the brine discharge to minimize the load on additional stages of RO membranes. One of the most critical considerations influencing the selection of an effective NF is the water type, which is expected here by calculation of some hydrochemical parameters (major ions, hypothetical soluble salts (electrolyte), and saturation indices). NF experiments were undertaken on a lab-scale using a low-pressure hand-made system of 4–7 bar. Synthetic single salts solutions and two real brine water discharge (brackish (BWRO) and seawater (SWRO) desalination plants) were used as a feed solution for NF system. The chemical characteristics of the RO-feed, RO-brine, NF-permeate, and NF-reject in were investigated. Electrolyte concentrations and saturation indices were determined based on the concentration of the major ions and the NETPATH software package, respectively. Calculations reveal that the brine concentrate samples contained mostly MgSO4 and MgCl2 soluble salts. The results show that 79–89% of the total dissolved salts (TDS) and 96–98% of the total hardness (TH) were retained using the NF process. The salt rejection of the NF membrane follows the order of CaSO4, Na2SO4, MgSO4, MgCl2, and NaCl with a percent of 97.4, 97.3, 95.2, 93.4, and 79%, respectively. Full article
(This article belongs to the Special Issue Membrane Processes for the Metal-ion/Pollutants Detection on Water and Treatment of Industrial Wastewaters)
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9 pages, 1735 KiB  
Communication
Oxygen Enrichment Membranes for Kuwait Power Plants: A Case Study
by Yousef Alqaheem and Fajer Alswaileh
Membranes 2021, 11(3), 211; https://doi.org/10.3390/membranes11030211 - 17 Mar 2021
Cited by 3 | Viewed by 2852
Abstract
Power plants are considered as the major source of carbon dioxide pollution in Kuwait. The gas is released from the combustion of fuel with air to convert water into steam. It has been proven that the use of enriched oxygen can reduce fuel [...] Read more.
Power plants are considered as the major source of carbon dioxide pollution in Kuwait. The gas is released from the combustion of fuel with air to convert water into steam. It has been proven that the use of enriched oxygen can reduce fuel consumption and minimize emissions. In this study, UniSim (Honeywell, Charlotte, NC, USA) was used to estimate the fuel savings and carbon dioxide emissions of the largest power plant in Kuwait (Alzour). Results showed that at 30 mol% oxygen, the fuel consumption was lowered by 8%, with a reduction in carbon dioxide emissions by 3524 tons per day. An economic analysis was performed on the use of a membrane unit to produce 30 mol% oxygen. At current market prices, the unit is not economical. However, the system can achieve a payback duration of 3 years if natural gas price increases to USD 6.74 or the compressor cost decreases to USD 52 per kW. Currently, the research and development sector is targeting a membrane fabrication cost of less than USD 10 per m2 to make the membrane process more attractive. Full article
(This article belongs to the Special Issue Novel Membrane Materials and Membrane Processes)
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12 pages, 814 KiB  
Article
ECMO Retrieval over the Mediterranean Sea: Extending Hospital Arms
by Brianna A. Hildreth, Giovanna Panarello, Gennaro Martucci, Fabio Tuzzolino, Alberto Piacentini, Giovanna Occhipinti, Andrea Giunta, Fabio Genco, Giuseppe M. Raffa, Michele Pilato, Guido Capitanio and Antonio Arcadipane
Membranes 2021, 11(3), 210; https://doi.org/10.3390/membranes11030210 - 17 Mar 2021
Cited by 5 | Viewed by 3405
Abstract
The retrieval and transport of patients from peripheral hospitals to high volume extracorporeal membrane oxygenation (ECMO) centers aims to reduce complications and improve survival. In Sicily (Italy), our institute houses a mobile ECMO team that serves a population of around 10 million people [...] Read more.
The retrieval and transport of patients from peripheral hospitals to high volume extracorporeal membrane oxygenation (ECMO) centers aims to reduce complications and improve survival. In Sicily (Italy), our institute houses a mobile ECMO team that serves a population of around 10 million people for a vast area in southern Italy and Malta. This observational, descriptive study includes all patients that required veno–venous (V-V) ECMO and transport by a mobile team between October 2009 and May 2020. Linear and multiple logistic regressions were applied to explore the risk factors for mortality in the ICU. Kaplan–Meier estimates were generated to predict the survival in patients transported by helicopter or ambulance, and the two cohorts were compared according to their baseline characteristics. Of 122 patients transported, 89 (73%) survived to ICU discharge (50 (41%) patients were transported by ambulance, and 72 (59%) were transported by helicopter). Independent predictive factors associated with mortality in a stepwise multiple regression model were prone positioning, acute kidney injury, and the number of days spent on mechanical ventilation (MV). Kaplan–Meier estimates for survival favored the helicopter cohort (79%) rather than the ambulance cohort (64%). Patients transported by helicopter had better pre-ECMO profiles, with shorter hospital and ICU stays, a shorter duration of MV use, and higher RESP scores, which indicate better survival probabilities. ECMO transport can be carried out safely over long distances; in rural areas with underdeveloped roads, transportation via helicopter or ambulance can extend the arm of the hospital to remote areas. Early ECMO initiation can be crucial in improving survival outcomes, and when transportation is the limiting factor to starting ECMO support, it should be attempted at the earliest logistical stage possible. Full article
(This article belongs to the Special Issue Challenges in the Extracorporeal Membrane Oxygenation Era)
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11 pages, 572 KiB  
Review
Modalities of Left Ventricle Decompression during VA-ECMO Therapy
by Juan Pablo Ricarte Bratti, Yiorgos Alexandros Cavayas, Pierre Emmanuel Noly, Karim Serri and Yoan Lamarche
Membranes 2021, 11(3), 209; https://doi.org/10.3390/membranes11030209 - 16 Mar 2021
Cited by 16 | Viewed by 4546
Abstract
Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is used to sustain circulatory and respiratory support in patients with severe cardiogenic shock or refractory cardiac arrest. Although VA-ECMO allows adequate perfusion of end-organs, it may have detrimental effects on myocardial recovery. Hemodynamic consequences on the left [...] Read more.
Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is used to sustain circulatory and respiratory support in patients with severe cardiogenic shock or refractory cardiac arrest. Although VA-ECMO allows adequate perfusion of end-organs, it may have detrimental effects on myocardial recovery. Hemodynamic consequences on the left ventricle, such as the increase of afterload, end-diastolic pressure and volume, can lead to left ventricular (LV) distention, increase of myocardial oxygen consumption and delayed LV function recovery. LV distention occurs in almost 50% of patients supported with VA-ECMO and is associated with an increase in morbidity and mortality. Thus, recognizing, preventing and treating LV distention is key in the management of these patients. In this review, we aim to discuss the pathophysiology of LV distention and to describe the strategies to unload the LV in patients supported with VA-ECMO. Full article
(This article belongs to the Special Issue Challenges in the Extracorporeal Membrane Oxygenation Era)
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9 pages, 236 KiB  
Article
Initial Arterial pCO2 and Its Course in the First Hours of Extracorporeal Cardiopulmonary Resuscitation Show No Association with Recovery of Consciousness in Humans: A Single-Centre Retrospective Study
by Loes Mandigers, Corstiaan A. den Uil, Jeroen J. H. Bunge, Diederik Gommers and Dinis dos Reis Miranda
Membranes 2021, 11(3), 208; https://doi.org/10.3390/membranes11030208 - 15 Mar 2021
Cited by 3 | Viewed by 2257
Abstract
Background: Cardiac arrest is a severe condition with high mortality rates, especially in the case of prolonged low-flow durations resulting in severe ischaemia and reperfusion injury. Changes in partial carbon dioxide concentration (pCO2) may aggravate this injury. Extracorporeal cardiopulmonary resuscitation (ECPR) [...] Read more.
Background: Cardiac arrest is a severe condition with high mortality rates, especially in the case of prolonged low-flow durations resulting in severe ischaemia and reperfusion injury. Changes in partial carbon dioxide concentration (pCO2) may aggravate this injury. Extracorporeal cardiopulmonary resuscitation (ECPR) shortens the low-flow duration and enables close regulation of pCO2. We examined whether pCO2 is associated with recovery of consciousness. Methods: We retrospectively analysed ECPR patients ≥ 16 years old treated between 2010 and 2019. We evaluated initial arterial pCO2 and the course of pCO2 ≤ 6 h after initiation of ECPR. The primary outcome was the rate of recovery of consciousness, defined as Glasgow coma scale motor score of six. Results: Out of 99 ECPR patients, 84 patients were eligible for this study. The mean age was 47 years, 63% were male, 93% had a witnessed arrest, 45% had an out-of-hospital cardiac arrest, and 38% had a recovery of consciousness. Neither initial pCO2 (Odds Ratio (OR) 0.93, 95% confidence interval 95% (CI) 0.78–1.08) nor maximum decrease of pCO2 (OR 1.03, 95% CI 0.95–1.13) was associated with the recovery of consciousness. Conclusion: Initial arterial pCO2 and the course of pCO2 in the first six hours after initiation of ECPR were not associated with the recovery of consciousness. Full article
(This article belongs to the Special Issue Advances in Extracorporeal Membrane Oxygenation)
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12 pages, 28474 KiB  
Article
Stability of Monolithic MOF Thin Films in Acidic and Alkaline Aqueous Media
by Tawheed Hashem, Elvia P. Valadez Sanchez, Evgenia Bogdanova, Anna Ugodchikova, Alaa Mohamed, Matthias Schwotzer, Mohamed H. Alkordi and Christof Wöll
Membranes 2021, 11(3), 207; https://doi.org/10.3390/membranes11030207 - 15 Mar 2021
Cited by 16 | Viewed by 3953
Abstract
In the context of thin film nanotechnologies, metal-organic frameworks (MOFs) are currently intensively explored in the context of both, novel applications and as alternatives to existing materials. When it comes to applications under relatively harsh conditions, in several cases it has been noticed [...] Read more.
In the context of thin film nanotechnologies, metal-organic frameworks (MOFs) are currently intensively explored in the context of both, novel applications and as alternatives to existing materials. When it comes to applications under relatively harsh conditions, in several cases it has been noticed that the stability of MOF thin films deviates from the corresponding standard, powdery form of MOFs. Here, we subjected SURMOFs, surface-anchored MOF thin films, fabricated using layer-by layer methods, to a thorough characterization after exposure to different harsh aqueous environments. The stability of three prototypal SURMOFs, HKUST-1, ZIF-8, and UiO-66-NH2 was systematically investigated in acidic, neutral, and basic environments using X-ray diffraction and electron microscopy. While HKUST-1 films were rather unstable in aqueous media, ZIF-8 SURMOFs were preserved in alkaline environments when exposed for short periods of time, but in apparent contrast to results reported in the literature for the corresponding bulk powders- not stable in neutral and acidic environments. UiO-66-NH2 SURMOFs were found to be stable over a large window of pH values. Full article
(This article belongs to the Section Membrane Applications)
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18 pages, 12534 KiB  
Review
Progress and Perspectives of Desalination in China
by Guoling Ruan, Min Wang, Zihan An, Guorong Xu, Yunhong Ge and Heli Zhao
Membranes 2021, 11(3), 206; https://doi.org/10.3390/membranes11030206 - 15 Mar 2021
Cited by 20 | Viewed by 6056
Abstract
In recent decades, the ever-growing demands for clean water in households and industries have urged researchers to take every possible step to deal with the global water crisis. Seawater desalination has turned out to be the most promising and efficient way to provide [...] Read more.
In recent decades, the ever-growing demands for clean water in households and industries have urged researchers to take every possible step to deal with the global water crisis. Seawater desalination has turned out to be the most promising and efficient way to provide clean water. Owing to the advancement of synthetic chemistries and technologies, great success has been achieved in the desalination and utilization of seawater worldwide. China, with the world’s largest population, has pushed the development of desalination and multipurpose utilization of seawater further in respect of materials, technologies and services, etc. This review reports recent progress of desalination technologies accomplished in China, from the viewpoints of facilities and equipment, collaborations, technologies, applications, research abilities, services, and standard systems. Inspired by the Fourteenth Five-year Plan, it also proposes future perspectives of desalination in China. Full article
(This article belongs to the Special Issue Seawater Reverse Osmosis Desalination)
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13 pages, 9126 KiB  
Article
Substrate-Independent, Regenerable Anti-Biofouling Coating for Polymeric Membranes
by Juan Zhang, Guang Wang, Jianhua Zhang, Zhiguang Xu, Yan Zhao, Yichao Wang, Fenghua She, Stephen Gray and Lingxue Kong
Membranes 2021, 11(3), 205; https://doi.org/10.3390/membranes11030205 - 13 Mar 2021
Cited by 4 | Viewed by 2830
Abstract
Biofouling is a common but significant issue in the membrane process as it reduces permeate flux, increases energy costs, and shortens the life span of membranes. As an effective antibacterial agent, a small amount of silver nanoparticles (AgNPs) immobilized on membrane surfaces will [...] Read more.
Biofouling is a common but significant issue in the membrane process as it reduces permeate flux, increases energy costs, and shortens the life span of membranes. As an effective antibacterial agent, a small amount of silver nanoparticles (AgNPs) immobilized on membrane surfaces will alleviate the membrane from biofouling. However, loading AgNPs on the membrane surface remains a challenge due to the low loading efficiency or the lack of bonding stability between AgNPs and the membrane surface. In this study, a substrate-independent method is reported to immobilize silver nanoparticles on polymeric membrane surfaces by firstly modifying the membrane surface with functional groups and then forming silver nanoparticles in situ. The obtained membranes had good anti-biofouling properties as demonstrated from disk diffusion and anti-biofouling tests. The silver nanoparticles were stably immobilized on the membrane surfaces and easily regenerated. This method is applicable to various polymeric micro-, ultra-, nano-filtration and reverse osmosis (RO) membranes. Full article
(This article belongs to the Special Issue Nanostructured Membranes II)
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17 pages, 4470 KiB  
Article
“Artificial Wood” Lignocellulosic Membranes: Influence of Kraft Lignin on the Properties and Gas Transport in Tunicate-Based Nanocellulose Composites
by Ievgen Pylypchuk, Roman Selyanchyn, Tetyana Budnyak, Yadong Zhao, Mikael Lindström, Shigenori Fujikawa and Olena Sevastyanova
Membranes 2021, 11(3), 204; https://doi.org/10.3390/membranes11030204 - 13 Mar 2021
Cited by 8 | Viewed by 3732
Abstract
Nanocellulose membranes based on tunicate-derived cellulose nanofibers, starch, and ~5% wood-derived lignin were investigated using three different types of lignin. The addition of lignin into cellulose membranes increased the specific surface area (from 5 to ~50 m2/g), however the fine porous [...] Read more.
Nanocellulose membranes based on tunicate-derived cellulose nanofibers, starch, and ~5% wood-derived lignin were investigated using three different types of lignin. The addition of lignin into cellulose membranes increased the specific surface area (from 5 to ~50 m2/g), however the fine porous geometry of the nanocellulose with characteristic pores below 10 nm in diameter remained similar for all membranes. The permeation of H2, CO2, N2, and O2 through the membranes was investigated and a characteristic Knudsen diffusion through the membranes was observed at a rate proportional to the inverse of their molecular sizes. Permeability values, however, varied significantly between samples containing different lignins, ranging from several to thousands of barrers (10−10 cm3 (STP) cm cm−2 s−1 cmHg−1cm), and were related to the observed morphology and lignin distribution inside the membranes. Additionally, the addition of ~5% lignin resulted in a significant increase in tensile strength from 3 GPa to ~6–7 GPa, but did not change thermal properties (glass transition or thermal stability). Overall, the combination of plant-derived lignin as a filler or binder in cellulose–starch composites with a sea-animal derived nanocellulose presents an interesting new approach for the fabrication of membranes from abundant bio-derived materials. Future studies should focus on the optimization of these types of membranes for the selective and fast transport of gases needed for a variety of industrial separation processes. Full article
(This article belongs to the Collection Polymeric Membranes: Science, Materials and Applications)
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9 pages, 7622 KiB  
Communication
Effect of Initial Water Flux on the Performance of Anaerobic Membrane Bioreactor: Constant Flux Mode versus Varying Flux Mode
by Xiawen Yi, Meng Zhang, Weilong Song and Xinhua Wang
Membranes 2021, 11(3), 203; https://doi.org/10.3390/membranes11030203 - 13 Mar 2021
Cited by 4 | Viewed by 2058
Abstract
Anaerobic membrane bioreactors (AnMBRs) have aroused growing interest in wastewater treatment and energy recovery. However, serious membrane fouling remains a critical hindrance to AnMBRs. Here, a novel membrane fouling mitigation via optimizing initial water flux is proposed, and its feasibility was evaluated by [...] Read more.
Anaerobic membrane bioreactors (AnMBRs) have aroused growing interest in wastewater treatment and energy recovery. However, serious membrane fouling remains a critical hindrance to AnMBRs. Here, a novel membrane fouling mitigation via optimizing initial water flux is proposed, and its feasibility was evaluated by comparing the membrane performance in AnMBRs between constant flux and varying flux modes. Results indicated that, compared with the constant flux mode, varying flux mode significantly prolonged the membrane operating time by mitigating membrane fouling. Through the analyses of fouled membranes under two operating modes, the mechanism of membrane fouling mitigation was revealed as follows: A low water flux was applied in stage 1 which slowed down the interaction between foulants and membrane surface, especially reduced the deposition of proteins on the membrane surface and formed a thin and loose fouling layer. Correspondingly, the interaction between foulants was weakened in the following stage 2 with a high water flux and, subsequently, the foulants absorbed on the membrane surface was further reduced. In addition, flux operating mode had no impact on the contaminant removal in an AnMBR. This study provides a new way of improving membrane performance in AnMBRs via a varying flux operating mode. Full article
(This article belongs to the Special Issue Membrane Bioreactors: Recent Advancements, Current Challenges and Future Opportunities)
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15 pages, 4482 KiB  
Article
Enhanced Gas Separation Prowess Using Functionalized Lignin-Free Lignocellulosic Biomass/Polysulfone Composite Membranes
by Abiodun Abdulhameed Amusa, Abdul Latif Ahmad and Adewole Kayode Jimoh
Membranes 2021, 11(3), 202; https://doi.org/10.3390/membranes11030202 - 13 Mar 2021
Cited by 8 | Viewed by 2855
Abstract
Delignified lignocellulosic biomass was functionalized with amine groups. Then, the pretreated lignin-free date pits cellulose and the amine-functionalized-date pits cellulose (0–5 wt%) were incorporated into a polysulfone polymer matrix to fabricate composite membranes. The amine groups give additional hydrogen bonding to those existing [...] Read more.
Delignified lignocellulosic biomass was functionalized with amine groups. Then, the pretreated lignin-free date pits cellulose and the amine-functionalized-date pits cellulose (0–5 wt%) were incorporated into a polysulfone polymer matrix to fabricate composite membranes. The amine groups give additional hydrogen bonding to those existing from the hydroxyl groups in the date pits cellulose. The approach gives an efficient avenue to enhance the CO2 molecules’ transport pathways through the membrane matrix. The interactions between phases were investigated via Fourier transformed infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), whereas pure gases (CO2 and N2) were used to evaluate the gas separation performances. Additionally, the thermal and mechanical properties of the fabricated composites were tested. The pure polysulfone membrane achieved an optimum separation performance at 4 Bar. The optimum separation performance for the composite membranes is achieved at 2 wt%. About 32% and 33% increments of the ideal CO2/N2 selectivity is achieved for the lignin-free date pits cellulose composite membrane and the amine-functionalized-date pits cellulose composite membrane, respectively. Full article
(This article belongs to the Section Polymeric Membranes)
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15 pages, 6086 KiB  
Article
Comprehensive Analysis of Foulants in an Ultrafiltration Membrane Used for the Treatment of Bleach Plant Effluent in a Sulfite Pulp Mill
by Gregor Rudolph, Basel Al-Rudainy, Johan Thuvander and Ann-Sofi Jönsson
Membranes 2021, 11(3), 201; https://doi.org/10.3390/membranes11030201 - 12 Mar 2021
Cited by 4 | Viewed by 2723
Abstract
Fouling is a major obstacle in the introduction of membrane processes in new applications in the pulping industry. Due to the complex nature of the feed solutions, complementary analysis methods are usually needed to identify the substances involved. Four different methods were used [...] Read more.
Fouling is a major obstacle in the introduction of membrane processes in new applications in the pulping industry. Due to the complex nature of the feed solutions, complementary analysis methods are usually needed to identify the substances involved. Four different methods were used for the comprehensive analysis of a membrane removed from an ultrafiltration plant treating alkaline bleach plant effluent in a sulfite pulp mill to identify the substances causing fouling. Magnesium was detected both on the membrane surface and in the nonwoven membrane backing and a small amount of polysaccharides was detected after acid hydrolysis of the fouled membrane. This study provides information on foulants, which can be used to improve processing conditions and cleaning protocols and thus the membrane performance in pulp mill separation processes. It also provides an overview of the usefulness of various analytical methods. Full article
(This article belongs to the Special Issue Recent Advances in Membrane Materials and Membrane Processes for Water and Wastewater Treatment)
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11 pages, 1959 KiB  
Article
Identification of Anthocyanins and Their Fouling Mechanisms during Non-Thermal Nanofiltration of Blueberry Aqueous Extracts
by Ming Cai, Chunfang Xie, Huazhao Zhong, Baoming Tian and Kai Yang
Membranes 2021, 11(3), 200; https://doi.org/10.3390/membranes11030200 - 12 Mar 2021
Cited by 11 | Viewed by 2057
Abstract
Organic fouling in the nanofiltration (NF) process, which is a non-thermal technology to recover active components, is a critical problem limiting its applications. This study seeks to identify the anthocyanins on the NF membrane and explore their fouling mechanisms during concentration of blueberry [...] Read more.
Organic fouling in the nanofiltration (NF) process, which is a non-thermal technology to recover active components, is a critical problem limiting its applications. This study seeks to identify the anthocyanins on the NF membrane and explore their fouling mechanisms during concentration of blueberry extracts. Seven kinds of monomeric anthocyanins in foulants—delphinidin-3-O-galactoside, delphinidin-3-O-glucoside, delphinidin-3-O-arabinoside, cyanidin-3-O-galactoside, petunidin-3-O-galactoside, peonidin-3-O-glucoside, and malvidin-3-O-glucoside—were identified. Moreover, chalcone, myricetin derivative, and an unknown substance with [M+H]+ at m/z 261.1309, which is the fragment ion corresponding to the break of glycoside bond of anthocyanins, were obtained. Interactions between anthocyanins and membrane made from polyamide were principally governed by the CH-π and π-π stacking of aromatic rings, the establishment of hydrogen bonds, and electrostatic interaction. This study will be helpful to further control fouling and choice of cleaning agents in concentration of anthocyanins-rich extracts. Full article
(This article belongs to the Section Membrane Physics and Theory)
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