Membranes

15 pages, 9467 KiB

Open AccessArticle

Study of the Removal Efficiency of Chromium Ions Using a Membrane by Electro-Kinetic Technique from Sludge

by Nabaa S. Hadi and Huda H. Awadh

Membranes 2023, 13(9), 806; https://doi.org/10.3390/membranes13090806 - 21 Sep 2023

Viewed by 1336

Recently, electro-kinetic (EK) remediation has become more popular as a novel method for removing chromium contamination from soil. This approach, however, is ineffective since it uses both cationic and anionic forms of chromium. In this study, a membrane-based technique was employed to increase [...] Read more.

Recently, electro-kinetic (EK) remediation has become more popular as a novel method for removing chromium contamination from soil. This approach, however, is ineffective since it uses both cationic and anionic forms of chromium. In this study, a membrane-based technique was employed to increase the efficiency of the electro-kinetic removal of chromium. Chromium removal from polluted sludge was studied using four bench-scale experiments. Two of these experiments employed distilled water (EK

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1 and EK

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2 and membrane), whereas the other used acetic acid as the catholyte (EK

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3 and EK

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4 and membrane). The pH, total chromium, and fractionation of chromium in the sludge were measured after remediation. In the EK

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1, EK

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2 and membrane, and EK

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3 and EK

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4 and membrane trials, the average removal efficiencies of total chromium were 47.6%, 58.6%, and 74.4%, 79.6%, respectively. In contrast to the electro-kinetic remediation strategy, which left approximately 80% of the sludge neutral or alkaline after treatment, the membrane created acidic soil conditions throughout the sludge. For example, the high field intensity used in the membrane tests may have helped to facilitate chromium desorption, dissolution, and separation from the sludge and enhanced chromium mobility. The findings show that the membrane can improve the effectiveness of chromium removal from sludge when utilized in the EK remediation process. Full article

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

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14 pages, 3073 KiB

Open AccessArticle

Copolyimide Brushes as a Component of a Hybrid Poly(phenylene Oxide) Membrane for Controlling Gas Separation: Effect of Water, Methanol, and Hexane Vapors

by Nadezhda Tian, Alexandra Pulyalina, Ilya Faykov, Iosif Gofman, Konstantin Zolotovsky and Galina Polotskaya

Membranes 2023, 13(9), 805; https://doi.org/10.3390/membranes13090805 - 20 Sep 2023

Viewed by 1385

Abstract

The effect of water, methanol, and hexane vapors on gas permeability was studied in a hybrid membrane containing 5 wt% copolyimide brushes with poly(methyl methacrylate) side chains (PI-g-PMMA) in a poly(phenylene oxide) (PPO) matrix, and in a pristine PPO membrane. These membranes in [...] Read more.

The effect of water, methanol, and hexane vapors on gas permeability was studied in a hybrid membrane containing 5 wt% copolyimide brushes with poly(methyl methacrylate) side chains (PI-g-PMMA) in a poly(phenylene oxide) (PPO) matrix, and in a pristine PPO membrane. These membranes in the form of dense nonporous films were further examined by atomic force microscopy (AFM) and scanning electron microscopy (SEM), as well as by measuring their mechanical and gas transport properties. A gas separation study of the membranes in a dry state and the membranes saturated with water, methanol, and hexane vapors was performed to estimate the effect of each vapor on the H₂, CO₂, N₂ permeability and selectivity in the separation of H₂/N₂ and CO₂/N₂ pairs. In general, saturation with water, methanol, and hexane vapors caused a decrease in the gas permeability of both membranes. The hybrid membrane containing copolyimide brushes demonstrated enhanced selectivity in the separation of H₂/N₂ and CO₂/N₂ pairs. It was found that a special effect of the vapors used for membrane saturation is associated with their molar volume. The solubility and diffusion coefficients of N₂ and CO₂ were obtained by Grand Canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations. Full article

(This article belongs to the Special Issue Fabrication, Characterization and Application of Organic/Inorganic Film Membranes and Advanced Materials (Volume III))

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18 pages, 4576 KiB

Open AccessArticle

Experimental Investigation of a Plate–Frame Water Gap Membrane Distillation System for Seawater Desalination

by Dahiru U. Lawal, Ismail Abdulazeez, Qusay F. Alsalhy, Jamilu Usman, Sani. I. Abba, Ibrahim B. Mansir, Ravishankar Sathyamurthy, Noel Jacob Kaleekkal and Binash Imteyaz

Membranes 2023, 13(9), 804; https://doi.org/10.3390/membranes13090804 - 19 Sep 2023

Cited by 4 | Viewed by 1735

Abstract

This study presented a detailed investigation into the performance of a plate–frame water gap membrane distillation (WGMD) system for the desalination of untreated real seawater. One approach to improving the performance of WGMD is through the proper selection of cooling plate material, which [...] Read more.

This study presented a detailed investigation into the performance of a plate–frame water gap membrane distillation (WGMD) system for the desalination of untreated real seawater. One approach to improving the performance of WGMD is through the proper selection of cooling plate material, which plays a vital role in enhancing the gap vapor condensation process. Hence, the influence of different cooling plate materials was examined and discussed. Furthermore, two different hydrophobic micro-porous polymeric membranes of similar mean pore sizes were utilized in the study. The influence of key operating parameters, including the feed water temperature and flow rate, was examined against the system vapor flux and gained output ratio (GOR). In addition, the used membranes were characterized by means of different techniques in terms of surface morphology, liquid entry pressure, water contact angle, pore size distribution, and porosity. Findings revealed that, at all conditions, the PTFE membrane exhibits superior vapor flux and energy efficiency (GOR), with 9.36% to 14.36% higher flux at a 0.6 to 1.2 L/min feed flow rate when compared to the PVDF membrane. The copper plate, which has the highest thermal conductivity, attained the highest vapor flux, while the acrylic plate, which has an extra-low thermal conductivity, recorded the lowest vapor flux. The increasing order of GOR values for different cooling plates is acrylic < HDPE < copper < aluminum < brass < stainless steel. Results also indicated that increasing the feed temperature increases the vapor flux almost exponentially to a maximum flux value of 30.36 kg/m²hr. The system GOR also improves in a decreasing pattern to a maximum value of 0.4049. Moreover, a long-term test showed that the PTFE membrane, which exhibits superior hydrophobicity, registered better salt rejection stability. The use of copper as a cooling plate material for better system performance is recommended, while cooling plate materials with very low thermal conductivities, such as a low thermally conducting polymer, are discouraged. Full article

(This article belongs to the Special Issue Advanced Membrane Technology in Water Reuse and Desalination)

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21 pages, 13602 KiB

Open AccessArticle

Integrating Microbial Fuel Cell and Hydroponic Technologies Using a Ceramic Membrane Separator to Develop an Energy–Water–Food Supply System

by Chikashi Sato, Wilgince Apollon, Alejandro Isabel Luna-Maldonado, Noris Evelin Paucar, Monte Hibbert and John Dudgeon

Membranes 2023, 13(9), 803; https://doi.org/10.3390/membranes13090803 - 19 Sep 2023

Cited by 3 | Viewed by 2880

Abstract

In this study, a microbial fuel cell was integrated into a hydroponic system (MFC-Hyp) using a ceramic membrane as a separator. The MFC-Hyp is a passive system that allows the transport of nutrients from wastewater in the microbial fuel cell (MFC) to water [...] Read more.

In this study, a microbial fuel cell was integrated into a hydroponic system (MFC-Hyp) using a ceramic membrane as a separator. The MFC-Hyp is a passive system that allows the transport of nutrients from wastewater in the microbial fuel cell (MFC) to water in the hydroponic vessel (Hyp) through a ceramic membrane separator, with no external energy input. The performance of this system was examined using potato-process wastewater as a source of energy and nutrients (K, P, N) and garlic chives (Allium tuberosum) as a hydroponic plant. The results showed that based on dry weight, the leaves of Allium tuberosum grew 142% more in the MFC-Hyp than those of the plant in the Hyp without the MFC, in a 49-day run. The mass fluxes of K, P, and NO₃⁻-N from the MFC to the Hyp through the ceramic membrane were 4.18 ± 0.70, 3.78 ± 1.90, and 2.04 ± 0.98 µg s⁻¹m⁻², respectively. It was apparent that the diffusion of nutrients from wastewater in the MFC enhanced the plant growth in the Hyp. The MFC-Hyp in the presence of A. tuberosum produced the maximum power density of 130.2 ± 45.4 mW m⁻². The findings of this study suggest that the MFC-Hyp system has great potential to be a “carbon-neutral” technology that could be transformed into an important part of a diversified worldwide energy–water–food supply system. Full article

(This article belongs to the Special Issue Membrane-Based Technologies for Water and Energy Sustainability, 2nd Edition)

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20 pages, 1939 KiB

Open AccessReview

Development and Prospective Applications of 3D Membranes as a Sensor for Monitoring and Inducing Tissue Regeneration

by Hanning Wu, Jiawen Chen, Pengxiang Zhao, Mengyu Liu, Fei Xie and Xuemei Ma

Membranes 2023, 13(9), 802; https://doi.org/10.3390/membranes13090802 - 18 Sep 2023

Cited by 1 | Viewed by 2023

Abstract

For decades, tissue regeneration has been a challenging issue in scientific modeling and human practices. Although many conventional therapies are already used to treat burns, muscle injuries, bone defects, and hair follicle injuries, there remains an urgent need for better healing effects in [...] Read more.

For decades, tissue regeneration has been a challenging issue in scientific modeling and human practices. Although many conventional therapies are already used to treat burns, muscle injuries, bone defects, and hair follicle injuries, there remains an urgent need for better healing effects in skin, bone, and other unique tissues. Recent advances in three-dimensional (3D) printing and real-time monitoring technologies have enabled the creation of tissue-like membranes and the provision of an appropriate microenvironment. Using tissue engineering methods incorporating 3D printing technologies and biomaterials for the extracellular matrix (ECM) containing scaffolds can be used to construct a precisely distributed artificial membrane. Moreover, advances in smart sensors have facilitated the development of tissue regeneration. Various smart sensors may monitor the recovery of the wound process in different aspects, and some may spontaneously give feedback to the wound sites by releasing biological factors. The combination of the detection of smart sensors and individualized membrane design in the healing process shows enormous potential for wound dressings. Here, we provide an overview of the advantages of 3D printing and conventional therapies in tissue engineering. We also shed light on different types of 3D printing technology, biomaterials, and sensors to describe effective methods for use in skin and other tissue regeneration, highlighting their strengths and limitations. Finally, we highlight the value of 3D bioengineered membranes in various fields, including the modeling of disease, organ-on-a-chip, and drug development. Full article

(This article belongs to the Special Issue Artificial Models of Biological Membranes—2nd Edition)

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17 pages, 9502 KiB

Open AccessArticle

Membrane–Fabric Composite Filter Media for Continuous Cake Filtration without Gas Throughput Using Paste Dot Coating with Adhesive

by Nikolai Benz, Fabian Krull, Kai Nikolaus and Sergiy Antonyuk

Membranes 2023, 13(9), 801; https://doi.org/10.3390/membranes13090801 - 18 Sep 2023

Viewed by 1436

Abstract

In the field of liquid filtration, the realization of gas throughput-free cake filtration has been investigated for a long time. Cake filtration without gas throughput would lead to energy savings in general and would reduce the mechanically achievable residual moisture in filter cakes [...] Read more.

In the field of liquid filtration, the realization of gas throughput-free cake filtration has been investigated for a long time. Cake filtration without gas throughput would lead to energy savings in general and would reduce the mechanically achievable residual moisture in filter cakes in particular. The reason why gas throughput-free filtration could not be realized with fabrics so far is that the achievable pore sizes are not small enough, and that the associated capillary pressure is too low for gas throughput-free filtration. Microporous membranes can prevent gas flow through open pores and cracks in the filter cake at a standard differential pressure for cake filtration of 0.8 bar due to their smaller pore size. Since large-scale implementation with membranes was not yet successful due to their inadequate mechanical strength, this work focuses on the development and testing of a novel composite material. It combines the advantages of gas throughput-free filtration using membranes with the mechanical stability of fabrics. For the production of the composites, a paste dot coating with adhesive, which is a common method in the textile industry, was used. Based on filtration experiments, delamination and tensile tests, as well as µCT analysis, it is shown that this method is suitable for the production of composite filter materials for gas throughput-free cake filtration. Full article

(This article belongs to the Section Membrane Applications)

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19 pages, 8709 KiB

Open AccessArticle

Exploring the Role of Drug Repurposing in Bridging the Hypoxia–Depression Connection

by Ana Salomé Correia, Lara Marques, Armando Cardoso and Nuno Vale

Membranes 2023, 13(9), 800; https://doi.org/10.3390/membranes13090800 - 17 Sep 2023

Cited by 1 | Viewed by 1709

Abstract

High levels of oxidative stress are implicated in hypoxia, a physiological response to low levels of oxygen. Evidence supports a connection between this response and depression. Previous studies indicate that tryptophan hydroxylase can be negatively affected in hypoxia, impairing serotonin synthesis and downstream [...] Read more.

High levels of oxidative stress are implicated in hypoxia, a physiological response to low levels of oxygen. Evidence supports a connection between this response and depression. Previous studies indicate that tryptophan hydroxylase can be negatively affected in hypoxia, impairing serotonin synthesis and downstream pathways. Some studies also hypothesize that increasing hypoxia-inducible factor-1 (HIF-1) levels may be a new therapeutic modality for depression. Hence, this study delved into the influence of hypoxia on the cellular response to drugs designed to act in depression. By the induction of hypoxia in SH-SY5Y cells through a hypoxia incubator chamber or Cobalt Chloride treatment, the effect of Mirtazapine, an antidepressant, and other drugs that interact with serotonin receptors (TCB-2, Dextromethorphan, Ketamine, Quetiapine, Scopolamine, Celecoxib, and Lamotrigine) on SH-SY5Y cellular viability and morphology was explored. The selection of drugs was initially conducted by literature search, focusing on compounds with established potential for employment in depression therapy. Subsequently, we employed in silico approaches to forecast their ability to traverse the blood–brain barrier (BBB). This step was particularly pertinent as we aimed to assess their viability for inducing potential antidepressant effects. The effect of these drugs in hypoxia under the inhibition of HIF-1 by Echinomycin was also tested. Our results revealed that all the potential repurposed drugs promoted cell viability, especially when hypoxia was chemically induced. When combined with Echinomycin, all drugs decreased cellular viability, possibly by the inability to interact with HIF-1. Full article

(This article belongs to the Special Issue Membranes in Biophysics, Medicinal Chemistry and Pharmacology)

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21 pages, 2234 KiB

Open AccessArticle

Valorization of Sour Buttermilk (A Potential Waste Stream): Conversion to Powder Employing Reverse Osmosis and Spray Drying

by Subhadip Manik, Ganga Sahay Meena, Ashish Kumar Singh, Yogesh Khetra, Richa Singh, Sumit Arora and Raghu H. Vishweswaraiah

Membranes 2023, 13(9), 799; https://doi.org/10.3390/membranes13090799 - 17 Sep 2023

Cited by 1 | Viewed by 2192

Abstract

Reverse osmosis (RO) is known for the economic dewatering of dairy streams without any change in phase. At the household level, surplus milk is fermented and churned to obtain butter, which is subsequently heated to obtain clarified milk fat (ghee). The [...] Read more.

Reverse osmosis (RO) is known for the economic dewatering of dairy streams without any change in phase. At the household level, surplus milk is fermented and churned to obtain butter, which is subsequently heated to obtain clarified milk fat (ghee). The production of 1 kg ghee generates 15–20 kg sour buttermilk (SBM) as a by-product that is mostly drained. This causes a loss of milk solids and environmental pollution. The processing, preservation and valorization of SBM are quite challenging because of its low total solids (TS) and pH, poor heat stability and limited shelf life. This investigation aimed to transform SBM into a novel dried dairy ingredient. SBM was thermized, filtered, defatted and concentrated at 35 ± 1 °C, employing RO up to 3.62× (12.86%). The RO concentrate was subsequently converted into sour buttermilk powder (SBMP) by employing spray drying. SBMP was further characterized for its physicochemical, reconstitution and functional properties; rheological and morphological characteristics; and amino acid and fatty acid profiling, along with FTIR and XRD spectra. SBMP was “instant soluble-3 s” and exhibited excellent emulsion stability (80.70%), water binding capacity (4.34 g/g of protein), flowability (28.36°) and antioxidant properties. In nutshell, a process was developed for the valorization of sour buttermilk to a novel dairy ingredient by employing reverse osmosis and a spray-drying process. Full article

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

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14 pages, 2438 KiB

Open AccessArticle

Dimensional Transformation of Percolation Structure in Mixed-Matrix Membranes (MMMs)

by Alexey Grekhov and Yury Eremin

Membranes 2023, 13(9), 798; https://doi.org/10.3390/membranes13090798 - 16 Sep 2023

Viewed by 1240

Abstract

A large number of studies of mixed-matrix membranes (MMMs) have confirmed the possibility of obtaining new materials with unique transport properties, including for solving specific problems in the separation of mixtures of liquids and gases. The choice of particles with a given affinity [...] Read more.

A large number of studies of mixed-matrix membranes (MMMs) have confirmed the possibility of obtaining new materials with unique transport properties, including for solving specific problems in the separation of mixtures of liquids and gases. The choice of particles with a given affinity for the matrix and separable components allows researchers to adjust the selective properties of MMMs in a wide range, which changes the properties of MMMs in a wide range. However, even within the framework of the most complex percolation mechanism of the formation of the MMM structure, it is possible to explain only some of the observed effects. In particular, questions about the required particle concentration and fluctuation of properties in various MMM samples are still the subject of research. The results of the numerical modeling of such structures presented in this paper determined the possible causes of the observed deviations of the experimental results, for example, particle size dispersion, agglomeration, and interaction with the matrix. According to our research, the key factor that qualitatively changes the parameters of percolation structures is the ratio of the geometric dimensions of the system. We have confirmed in a wide range a significant change in the conditions of cluster formation and its power at different particle diameters and lengths (traditional parameters in percolation studies). But in our work, we additionally studied the effect on the cluster parameters of the interfacial layer and the anisotropy of the matrix (the transition from the cube to the film). The results obtained show that changing the parameters of the matrix–particle interaction affects agglomeration, and the degradation of the percolation structure is possible. That is, with an increase in concentration, the parameters of the percolation cluster, its power, and the probability of formation, may decrease. But even more negative changes in percolation structures are observed during the transition from a volumetric matrix to films. The anisotropy of space leads to the formation of percolation through the film in certain areas at low concentrations of particles. At the same time, in a significant part of the matrix, percolation between the film surfaces will be absent, and the effect of changing the properties of MMMs in the matrix as a whole decreases. Our study explains the observed instability of MMM properties at fixed concentrations and parameters of embedded particles, including the effect of reducing the influence of particles with increasing concentration. Full article

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

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16 pages, 1254 KiB

Open AccessArticle

Characterization and Applications of the Pectin Extracted from the Peel of Passiflora tripartita var. mollissima

by Minerva Rentería-Ortega, María de Lourdes Colín-Alvarez, Víctor Alfonso Gaona-Sánchez, Mayra C. Chalapud, Alitzel Belém García-Hernández, Erika Berenice León-Espinosa, Mariana Valdespino-León, Fatima Sarahi Serrano-Villa and Georgina Calderón-Domínguez

Membranes 2023, 13(9), 797; https://doi.org/10.3390/membranes13090797 - 16 Sep 2023

Cited by 2 | Viewed by 3153

Abstract

The inadequate management of organic waste and excessive use of plastic containers cause damage to the environment; therefore, different studies have been carried out to obtain new biomaterials from agricultural subproducts. The objective of this work was to evaluate the feasibility of using [...] Read more.

The inadequate management of organic waste and excessive use of plastic containers cause damage to the environment; therefore, different studies have been carried out to obtain new biomaterials from agricultural subproducts. The objective of this work was to evaluate the feasibility of using the pectin extracted from the peel of Passiflora tripartita var. mollissima (PT), characterizing its type and viability for the production of edible biodegradable films. In addition, films of two thicknesses (23.45 ± 3.02 µm and 53.34 ± 2.28 µm) were prepared. The results indicated that PT is an excellent raw material for the extraction of pectin, with high yields (23.02 ± 0.02%), high galacturonic acid content (65.43 ± 2.241%), neutral sugars (ribose, xylose, glucose) and a high degree of esterification (76.93 ± 1.65%), classifying it as a high-methoxy pectin. Regarding the films, they were malleable and flexible, with a water vapor permeability from 2.57 × 10⁻¹⁰ ± 0.046 to 0.13 × 10⁻¹⁰ ± 0.029 g/s mPa according to thickness, being similar to other Passiflora varieties of edible films. The pectin extraction yield from PT makes this fruit a promising material for pectin production and its chemical composition a valuable additive for the food and pharmaceutical industries. Full article

(This article belongs to the Special Issue Recent Advances in Biodegradable and Edible Biopolymer-Based Films)

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23 pages, 1829 KiB

Open AccessArticle

Inhomogeneous Canham–Helfrich Abscission in Catenoid Necks under Critical Membrane Mosaicity

by José Antonio Santiago and Francisco Monroy

Membranes 2023, 13(9), 796; https://doi.org/10.3390/membranes13090796 - 14 Sep 2023

Cited by 1 | Viewed by 1584

Abstract

The mechanical effects of membrane compositional inhomogeneities are analyzed in a process analogous to neck formation in cellular membranes. We cast on the Canham–Helfrich model of fluid membranes with both the spontaneous curvature and the surface tension being non-homogeneous functions along the cell [...] Read more.

The mechanical effects of membrane compositional inhomogeneities are analyzed in a process analogous to neck formation in cellular membranes. We cast on the Canham–Helfrich model of fluid membranes with both the spontaneous curvature and the surface tension being non-homogeneous functions along the cell membrane. The inhomogeneous distribution of necking forces is determined by the equilibrium mechanical equations and the boundary conditions as considered in the axisymmetric setting compatible with the necking process. To establish the role played by mechanical inhomogeneity, we focus on the catenoid, a surface of zero mean curvature. Analytic solutions are shown to exist for the spontaneous curvature and the constrictive forces in terms of the border radii. Our theoretical analysis shows that the inhomogeneous distribution of spontaneous curvature in a mosaic-like neck constrictional forces potentially contributes to the membrane scission under minimized work in living cells. Full article

(This article belongs to the Special Issue Structure and Conformation of Lipid Membranes)

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18 pages, 2146 KiB

Open AccessEditor’s ChoiceArticle

Polymeric Inclusion Membranes Based on Ionic Liquids for Selective Separation of Metal Ions

by Adrián Hernández-Fernández, Eduardo Iniesta-López, Anahí Ginestá-Anzola, Yolanda Garrido, Antonia Pérez de los Ríos, Joaquín Quesada-Medina and Francisco José Hernández-Fernández

Membranes 2023, 13(9), 795; https://doi.org/10.3390/membranes13090795 - 13 Sep 2023

Cited by 3 | Viewed by 2052

Abstract

In this work, poly(vinyl chloride)-based polymeric ionic liquid inclusion membranes were used in the selective separation of Fe(III), Zn(II), Cd(II), and Cu(II) from hydrochloride aqueous solutions. The ionic liquids under study were 1-octyl-3-methylimidazolium hexafluorophosphate, [omim⁺][PF₆⁻] and methyl trioctyl [...] Read more.

In this work, poly(vinyl chloride)-based polymeric ionic liquid inclusion membranes were used in the selective separation of Fe(III), Zn(II), Cd(II), and Cu(II) from hydrochloride aqueous solutions. The ionic liquids under study were 1-octyl-3-methylimidazolium hexafluorophosphate, [omim⁺][PF₆⁻] and methyl trioctyl ammonium chloride, [MTOA⁺][Cl⁻]. For this purpose, stability studies of different IL/base polymer compositions against aqueous phases were carried out. Among all polymer inclusion membranes studied, [omim⁺][PF₆⁻]/PVC membranes at a ratio of 30/70 and [MTOA⁺][Cl⁻]/PVC membranes at a ratio of 70/30 were able to retain up to 82% and 48% of the weight of the initial ionic liquid, respectively, after being exposed to a solution of metal ions in 1 M HCl for 2048 h (85 days). It was found that polymer inclusion membranes based on the ionic liquid methyl trioctyl ammonium chloride allowed the selective separation of Zn(II)/Cu(II) and Zn(II)/Fe(III) mixtures with separation factors of 1996, 606 and, to a lesser extent but also satisfactorily, Cd(II)/Cu(II) mixtures, with a separation factor of 112. Therefore, selecting the appropriate ionic liquid/base polymer mixture makes it possible to create polymeric inclusion membranes capable of selectively separating target metal ions. Full article

(This article belongs to the Special Issue Advances in Modeling, Control, and Optimization of Membrane Distillation and Membrane Separation Processes)

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16 pages, 5494 KiB

Open AccessArticle

Effect of Blended Perfluorinated Sulfonic Acid Ionomer Binder on the Performance of Catalyst Layers in Polymer Electrolyte Membrane Fuel Cells

by Beom-Seok Kim, Jong-Hyeok Park and Jin-Soo Park

Membranes 2023, 13(9), 794; https://doi.org/10.3390/membranes13090794 - 13 Sep 2023

Cited by 3 | Viewed by 2075

Abstract

In this study, blended perfluorinated sulfonic acid (PFSA) ionomers with equivalent weights (EWs, g/mol) of ~1000, 980, and 830 are prepared. Catalyst layers (CLs), using blended PFSA ionomers, with different side chain lengths and EWs are investigated and compared to CLs using single [...] Read more.

In this study, blended perfluorinated sulfonic acid (PFSA) ionomers with equivalent weights (EWs, g/mol) of ~1000, 980, and 830 are prepared. Catalyst layers (CLs), using blended PFSA ionomers, with different side chain lengths and EWs are investigated and compared to CLs using single ionomers. The ion exchange capacity results confirm that blended ionomers have the target EWs. As a result, blended ionomers exhibit higher ion conductivity than single ionomers at all temperatures due to the higher water uptake of the blended ionomers. This implies that blended ionomers have a bulk structure to form a competent free volume compared to single ionomers. Blended ionomers with short side chains and low EWs can help reduce the activation energy in proton conduction due to enhanced hydrophobic and hydrophilic segregation. In addition, when using the blended ionomer, the CLs form a more porous microstructure to help reduce the resistance of oxygen transport and contributes to lower mass transfer loss. This effect is proven in fuel cell operations at not a lower temperature (70 °C) and full humidification (100%) but at an elevated temperature (80 °C) and lower relative humidity (50 and 75%). Blended ionomer-based CLs with a higher water uptake and porous CL structure result in improved fuel cell performance with better mass transport than single ionomer-based CLs. Full article

(This article belongs to the Special Issue Proton-Conducting Membranes - 2nd Edition)

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17 pages, 8839 KiB

Open AccessArticle

Facile Preparation of Durable and Eco-Friendly Superhydrophobic Filter with Self-Healing Ability for Efficient Oil/Water Separation

by Wei Xin Voo, Woon Chan Chong, Hui Chieh Teoh, Woei Jye Lau, Yi Jing Chan and Ying Tao Chung

Membranes 2023, 13(9), 793; https://doi.org/10.3390/membranes13090793 - 13 Sep 2023

Cited by 1 | Viewed by 1699

Abstract

The superhydrophobic feature is highly desirable for oil/water separation (OWS) operation to achieve excellent separation efficiency. However, using hazardous materials in fabricating superhydrophobic surfaces is always the main concern. Herein, superhydrophobic filters were prepared via an eco-friendly approach by anchoring silica particles (SiO [...] Read more.

The superhydrophobic feature is highly desirable for oil/water separation (OWS) operation to achieve excellent separation efficiency. However, using hazardous materials in fabricating superhydrophobic surfaces is always the main concern. Herein, superhydrophobic filters were prepared via an eco-friendly approach by anchoring silica particles (SiO₂) onto the cotton fabric surface, followed by surface coating using natural material—myristic acid via a dip coating method. Tetraethyl orthosilicate (TEOS) was used in the synthesis of SiO₂ particles from the silica sol. In addition, the impact of the drying temperature on the wettability of the superhydrophobic filter was investigated. Moreover, the pristine cotton fabric and as-prepared superhydrophobic cotton filters were characterised based on Fourier-transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX) and contact angle (CA) measurement. The superhydrophobic cotton filter was used to perform OWS using an oil-water mixture containing either chloroform, hexane, toluene, xylene or dichloroethane. The separation efficiency of the OWS using the superhydrophobic filter was as high as 99.9%. Moreover, the superhydrophobic fabric filter also demonstrated excellent durability, chemical stability, self-healing ability and reusability. Full article

(This article belongs to the Special Issue Surface and Interface Engineering of Membrane Composites)

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12 pages, 1002 KiB

Open AccessArticle

Screening of Commercial Organic Solvent Nanofiltration Membranes for Purification of Plastic Waste Pyrolysis Liquids

by Rick van Lin, Paulina A. Sosa Fernandez, Tymen Visser and Patrick de Wit

Membranes 2023, 13(9), 792; https://doi.org/10.3390/membranes13090792 - 12 Sep 2023

Viewed by 1748

Abstract

Increasing consumption rates of plastics, combined with the waste generated from their production, leads to several environmental problems. Presently, plastic recycling takes account of only about 10% of the plastic waste, which is achieved mainly through mechanical recycling. Chemical recycling methods, such as [...] Read more.

Increasing consumption rates of plastics, combined with the waste generated from their production, leads to several environmental problems. Presently, plastic recycling takes account of only about 10% of the plastic waste, which is achieved mainly through mechanical recycling. Chemical recycling methods, such as pyrolysis, could significantly increase overall recycling rates and reduce the need for the production of fossil-based chemicals. Produced pyrolysis oil can be used for the production of benzene, toluene and xylene (BTX) through catalytic upgrading or for the production of alkanes if used directly. Separation of high-value components in pyrolysis oil derived from plastic waste through traditional separation methods can be energy intensive. Organic solvent nanofiltration has been recognised as an alternative with very low energy consumption, as separation is not based on a phase transition. This work focuses on the screening of several (semi-) commercially available membranes using a simplified model mixture of pyrolysis oil obtained from plastics. Based on membrane performance, a selection of membranes was used to treat a feedstock obtained from the direct pyrolysis of plastics. This work shows that currently, commercial OSN membranes have promising separation performance on model mixtures while showing insufficient and non-selective separation at very low flux for complex mixtures derived from the pyrolysis of plastics. This indicates that OSN is indeed a promising technology but that membranes should likely be tailored to this specific application. Full article

(This article belongs to the Section Membrane Applications)

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18 pages, 6970 KiB

Open AccessArticle

Increasing Performance of Spiral-Wound Modules (SWMs) by Improving Stability against Axial Pressure Drop and Utilising Pulsed Flow

by Christian Kürzl, Martin Hartinger, Patrick Ong, Roland Schopf, Simon Schiffer and Ulrich Kulozik

Membranes 2023, 13(9), 791; https://doi.org/10.3390/membranes13090791 - 12 Sep 2023

Cited by 1 | Viewed by 2181

Abstract

Spacer-induced flow shadows and limited mechanical stability due to module construction and geometry are the main obstacles to improving the filtration performance and cleanability of microfiltration spiral-wound membranes (SWMs), applied to milk protein fractionation in this study. The goal of this study was [...] Read more.

Spacer-induced flow shadows and limited mechanical stability due to module construction and geometry are the main obstacles to improving the filtration performance and cleanability of microfiltration spiral-wound membranes (SWMs), applied to milk protein fractionation in this study. The goal of this study was first to improve filtration performance and cleanability by utilising pulsed flow in a modified pilot-scale filtration plant. The second goal was to enhance membrane stability against module deformation by flow-induced friction in the axial direction (“membrane telescoping”). This was accomplished by stabilising membrane layers, including spacers, at the membrane inlet by glue connections. Pulsed flow characteristics similar to those reported in previous lab-scale studies could be achieved by establishing an on/off bypass around the membrane module, thus enabling a high-frequency flow variation. Pulsed flow significantly increased filtration performance (target protein mass flow into the permeate increased by 26%) and cleaning success (protein removal increased by 28%). Furthermore, adding feed-side glue connections increased the mechanical membrane stability in terms of allowed volume throughput by ≥100% compared to unmodified modules, thus allowing operation with higher axial pressure drops, flow velocities and pulsation amplitudes. Full article

(This article belongs to the Section Membrane Applications)

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20 pages, 12066 KiB

Open AccessArticle

Phase Equilibria, Solidified Microstructure, and Hydrogen Transport Behaviour in the V-Ti-Co System

by Erhu Yan, Zhijie Guo, Limin Jia, Yihao Wang, Shuo Zhang, Tangwei Li, Yongjin Zou, Hailiang Chu, Huanzhi Zhang, Fen Xu and Lixian Sun

Membranes 2023, 13(9), 790; https://doi.org/10.3390/membranes13090790 - 12 Sep 2023

Cited by 1 | Viewed by 1312

Abstract

At present, the V-Ti-Co phase diagram is not established, which seriously hinders the subsequent development of this potential hydrogen permeation alloy system. To this end, this article constructed the first phase diagram of the V-Ti-Co system by using the CALculation of PHAse Diagrams [...] Read more.

At present, the V-Ti-Co phase diagram is not established, which seriously hinders the subsequent development of this potential hydrogen permeation alloy system. To this end, this article constructed the first phase diagram of the V-Ti-Co system by using the CALculation of PHAse Diagrams (CALPHAD) approach as well as relevant validation experiments. On this basis, hydrogen-permeable V_xTi₅₀Co_50−x (x = 17.5, 20.5, …, 32.5) alloys were designed, and their microstructure characteristics and hydrogen transport behaviour were further studied by XRD, SEM, EDS, and so on. It was found that six ternary invariant reactions are located in the liquidus projection, and the phase diagram is divided into eight phase regions by their connecting lines. Among them, some alloys in the TiCo phase region were proven to be promising candidate materials for hydrogen permeation. Typically, V_xTi₅₀Co_50−x (x = 17.5–23.5) alloys, which consist of the primary TiCo and the eutectic {bcc-(V, Ti) and TiCo} structure, show a high hydrogen permeability without hydrogen embrittlement. In particular, V_23.5Ti₅₀Co_26.5 exhibit the highest permeability of 4.05 × 10⁻⁸ mol H₂ m⁻¹s⁻¹Pa^−0.5, which is the highest value known heretofore in the V-Ti-Co system. The high permeability of these alloys is due in large part to the simultaneous increment of hydrogen solubility and diffusivity, and is closely related to the composition of hydrogen permeable alloys, especially the Ti content in the (V, Ti) phase. The permeability of this alloy system is much higher than those of Nb-TiCo and/or Nb-TiNi alloys. Full article

(This article belongs to the Special Issue Zeolitic Membranes for Gas and Liquid Separation: Synthesis and Applications)

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27 pages, 5314 KiB

Open AccessReview

Nanofiltration Membranes for the Removal of Heavy Metals from Aqueous Solutions: Preparations and Applications

by Alaa El Din Mahmoud and Esraa Mostafa

Membranes 2023, 13(9), 789; https://doi.org/10.3390/membranes13090789 - 12 Sep 2023

Cited by 18 | Viewed by 5275

Abstract

Water shortages are one of the problems caused by global industrialization, with most wastewater discharged without proper treatment, leading to contamination and limited clean water supply. Therefore, it is important to identify alternative water sources because many concerns are directed toward sustainable water [...] Read more.

Water shortages are one of the problems caused by global industrialization, with most wastewater discharged without proper treatment, leading to contamination and limited clean water supply. Therefore, it is important to identify alternative water sources because many concerns are directed toward sustainable water treatment processes. Nanofiltration membrane technology is a membrane integrated with nanoscale particle size and is a superior technique for heavy metal removal in the treatment of polluted water. The fabrication of nanofiltration membranes involves phase inversion and interfacial polymerization. This review provides a comprehensive outline of how nanoparticles can effectively enhance the fabrication, separation potential, and efficiency of NF membranes. Nanoparticles take the form of nanofillers, nanoembedded membranes, and nanocomposites to give multiple approaches to the enhancement of the NF membrane’s performance. This could significantly improve selectivity, fouling resistance, water flux, porosity, roughness, and rejection. Nanofillers can form nanoembedded membranes and thin films through various processes such as in situ polymerization, layer-by-layer assembly, blending, coating, and embedding. We discussed the operational conditions, such as pH, temperature, concentration of the feed solution, and pressure. The mitigation strategies for fouling resistance are also highlighted. Recent developments in commercial nanofiltration membranes have also been highlighted. Full article

(This article belongs to the Special Issue Sustainable Membrane Processes of Water Recycling and Purification)

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13 pages, 1255 KiB

Open AccessReview

TRP Channels: The Neglected Culprits in Breast Cancer Chemotherapy Resistance?

by Mayar Soussi, Alice Hasselsweiller and Dimitra Gkika

Membranes 2023, 13(9), 788; https://doi.org/10.3390/membranes13090788 - 12 Sep 2023

Viewed by 1792

Abstract

Breast cancer is a major health concern worldwide, and resistance to therapies remains a significant challenge in treating this disease. In breast cancer, Transient Receptor Potential (TRP) channels are well studied and constitute key players in nearly all carcinogenesis hallmarks. Recently, they have [...] Read more.

Breast cancer is a major health concern worldwide, and resistance to therapies remains a significant challenge in treating this disease. In breast cancer, Transient Receptor Potential (TRP) channels are well studied and constitute key players in nearly all carcinogenesis hallmarks. Recently, they have also emerged as important actors in resistance to therapy by modulating the response to various pharmaceutical agents. Targeting TRP channels may represent a promising approach to overcome resistance to therapies in breast cancer patients. Full article

(This article belongs to the Special Issue Function and Malfunction of Ion Channels in Biological Cell Membrane)

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18 pages, 3169 KiB

Open AccessArticle

Organic Compounds Responsible for the Fouling of Ultrafiltration Membrane Treating Algae-Laden Water

by Edwin Castilla-Rodriguez and Hongde Zhou

Membranes 2023, 13(9), 787; https://doi.org/10.3390/membranes13090787 - 12 Sep 2023

Cited by 2 | Viewed by 1534

Abstract

Fouling comparisons of the organic fractions in surface and algae-laden waters make it possible to determine the main compounds responsible for the fouling of ultrafiltration (UF) membranes. This study examined the fouling of UF membranes and its relationship to the characteristics of the [...] Read more.

Fouling comparisons of the organic fractions in surface and algae-laden waters make it possible to determine the main compounds responsible for the fouling of ultrafiltration (UF) membranes. This study examined the fouling of UF membranes and its relationship to the characteristics of the organic fractions found in drinking-water supply. Four types of water were prepared by combining natural organic matter (NOM) from lake water with algal organic matter (AOM) from four algae species commonly found in freshwater. Liquid chromatography–organic carbon detection (LC–OCD) and a fluorescence excitation–emission matrix (FEEM) were used to analyze the feed water and permeate to assess the interactions between and fouling behavior of the organic fractions. The results showed that the interaction of large-molecular-weight AOMs on the membrane surfaces and their transport through the membrane pores were the main fouling mechanisms. Polysaccharides followed by protein-like substances were the organic compounds responsible for the fouling of the UF membranes. The fouling affinity of these substances was attributed to two processes, the adsorption of their carboxyl, hydroxyl and cationic groups on the membrane surfaces, and the molecular complexation of their organic groups. The humic substances’ retention was marginal and attributed to the synergetic effects of the polysaccharides and proteins. Full article

(This article belongs to the Special Issue Membrane Fouling and Antifouling Strategies in Water and Wastewater Treatment)

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18 pages, 1991 KiB

Open AccessArticle

Effect of Birch Sap as Solvent and Source of Bioactive Compounds in Casein and Gelatine Films

by María Carpintero, Ismael Marcet, María Zornoza, Manuel Rendueles and Mario Díaz

Membranes 2023, 13(9), 786; https://doi.org/10.3390/membranes13090786 - 11 Sep 2023

Viewed by 1718

Abstract

Birch sap consists of a natural water-based solution with valuable compounds such as minerals, sugars, organic acids and phenolic compounds that can be used advantageously in the preparation of edible films. In this study, gelatine- and casein-based films were prepared using birch sap [...] Read more.

Birch sap consists of a natural water-based solution with valuable compounds such as minerals, sugars, organic acids and phenolic compounds that can be used advantageously in the preparation of edible films. In this study, gelatine- and casein-based films were prepared using birch sap as biopolymer solvent and source of bioactive compounds with the aim of developing new bioactive materials for food packaging. The physical, mechanical, barrier, antioxidant and iron-chelating properties of the obtained films were investigated. Birch sap enhanced the mechanical properties of the films by increasing puncture strength and flexibility, as well as their ultraviolet–visible light barrier properties. In addition, the presence of bioactive compounds endowed the birch sap films with an antioxidant capacity of almost 90% and an iron-chelating capacity of 40–50% with respect to the control films. Finally, to test these films as food packaging material, a photosensitive curcumin solution was packed and exposed to ultraviolet light. Tested films were able to protect curcumin against photodegradation, and the presence of bioactive compounds inside the birch-sap-enriched materials offered an additional 10% photoprotective effect compared to control films. Results showed the potential of birch sap as an environmentally friendly biopolymer solvent and plasticizer that can improve the mechanical and photoprotective properties of the prepared materials. Full article

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

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13 pages, 1912 KiB

Open AccessArticle

Investigation of Zebrafish Embryo Membranes at Epiboly Stage through Electrorotation Technique

by Aránzazu Sanchis-Otero, María Teresa Reina-Maldonado, José Roldán, Vicenta María Barragán and Sagrario Muñoz

Membranes 2023, 13(9), 785; https://doi.org/10.3390/membranes13090785 - 9 Sep 2023

Viewed by 1375

Abstract

A preliminary exploration of the physiology and morphology of the zebrafish embryo (ZFE) during the late-blastula and early-gastrula stages through its electrical properties was performed, applying the electrorotation (ROT) technique. This method, based on induced polarizability at the interfaces, was combined with an [...] Read more.

A preliminary exploration of the physiology and morphology of the zebrafish embryo (ZFE) during the late-blastula and early-gastrula stages through its electrical properties was performed, applying the electrorotation (ROT) technique. This method, based on induced polarizability at the interfaces, was combined with an analytical spherical shell model to obtain the best fit of empirical data and the desired information, providing a means of understanding the role of different membranes. Suspended in two solutions of low conductivity, the major compartments of the ZFE were electrically characterized, considering morphological data from both observed records and data from the literature. Membrane integrity was also analyzed for dead embryos. The low permeability and relatively high permittivity obtained for the chorion probably reflected both its structural characteristics and external conditions. Reasonable values were derived for perivitelline fluid according to the influx of water that occurs after the fertilization of the oocyte. The so-called yolk membrane, which comprises three different and contiguous layers at the epiboly stage, showed atypical electrical values of the membrane, as did the yolk core with a relatively low permittivity. The internal morphological complexity of the embryo itself could be addressed in future studies by developing an accurate geometric model. Full article

(This article belongs to the Special Issue Membranes and Membrane Processes in Medicine)

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3 pages, 199 KiB

Open AccessEditorial

Circular Economy in Membrane Technology

by Junkal Landaburu-Aguirre and Serena Molina

Membranes 2023, 13(9), 784; https://doi.org/10.3390/membranes13090784 - 8 Sep 2023

Cited by 1 | Viewed by 1243

Abstract

The European Union (EU) produces more than 2 [...] Full article

(This article belongs to the Special Issue Circular Economy in Membrane Technology)

16 pages, 7939 KiB

Open AccessArticle

Synthesis of Trimetallic Nanoparticle (NiCoPd)-Supported Carbon Nanofibers as a Catalyst for NaBH₄ Hydrolysis

by Ahmed Abutaleb, Ibrahim M. Maafa, Nasser Zouli, Ayman Yousef and M. M. El-Halwany

Membranes 2023, 13(9), 783; https://doi.org/10.3390/membranes13090783 - 7 Sep 2023

Cited by 3 | Viewed by 1257

Abstract

The generation of H₂ via the catalytic hydrolysis of sodium borohydride (SBH) has promise as a practical and secure approach to produce H₂, a secure and environmentally friendly energy source for the foreseeable future. In this study, distinctive trimetallic NiCoPd [...] Read more.

The generation of H₂ via the catalytic hydrolysis of sodium borohydride (SBH) has promise as a practical and secure approach to produce H₂, a secure and environmentally friendly energy source for the foreseeable future. In this study, distinctive trimetallic NiCoPd nanoparticle-supported carbon nanofibers (NiCoPd tri-NPs@CNFs) is synthesized via sol-gel and electrospinning approaches. The fabricated trimetallic catalysts show an excellent catalytic performance for the generation of H₂ from the hydrolysis of SBH. Standard physicochemical techniques were used to characterize the as-prepared NiCoPd tri-NPs@CNFs. The results show that NiCoPd tri-NPs@CNFs is formed, with an average particle size of about 21 nm. When compared to NiCo bimetallic NP @CNFS, all NiCoPd tri-NPs@CNFs formulations demonstrated greater catalytic activates for the hydrolysis of SBH. The improved catalytic activity may be due in the majority to the synergistic interaction between the three metals in the trimetallic architecture. Furthermore, the activation energy for the catalytic hydrolysis of SBH by the NiCoPd tri-NPs@CNFs was determined to be 16.30 kJ mol⁻¹. The kinetics studies show that the reaction is of a first order with respect to the catalyst loading amount and a half order with respect to the SBH concentration [SBH]. Full article

(This article belongs to the Special Issue Metallic Membrane—Future Prospect, Research Trends and Applicability)

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11 pages, 6811 KiB

Open AccessCommunication

Fabrication of Polycrystalline Zeolitic Imidazolate Framework Membranes by a Vapor-Phase Seeding Method

by Zhiqin Qiang, Zihao Yi, Jun-Wei Wang, Rahul Sampat Khandge and Xiaoli Ma

Membranes 2023, 13(9), 782; https://doi.org/10.3390/membranes13090782 - 7 Sep 2023

Cited by 1 | Viewed by 1456

Abstract

The reliable fabrication of polycrystalline zeolitic imidazolate framework (ZIF) membranes continues to pose challenges for their industrial applications. Here, we present a vapor-phase seeding approach that integrates atomic layer deposition (ALD) with ligand vapor treatment to synthesize ZIF membranes with high propylene/propane separation [...] Read more.

The reliable fabrication of polycrystalline zeolitic imidazolate framework (ZIF) membranes continues to pose challenges for their industrial applications. Here, we present a vapor-phase seeding approach that integrates atomic layer deposition (ALD) with ligand vapor treatment to synthesize ZIF membranes with high propylene/propane separation performance. This method began with depositing a ZnO coating onto the support surface via ALD. The support underwent treatment with 2-methylimidazole vapor to transform ZnO to ZIF-8, forming the seed layer. Subsequent secondary growth was employed at near-room temperature, allowing the seeds to grow into a continuous membrane. ZIF-8 membranes made on macroporous ceramic support by this method consistently demonstrated propylene permeances above 1 × 10⁻⁸ mol Pa⁻¹ m⁻² s⁻¹ and a propylene/propane separation factor exceeding 50. Moreover, we demonstrated the effectiveness of the vapor-phase seeding method in producing the ZIF-67 membrane. Full article

(This article belongs to the Special Issue Research Progress of Metal-Organic-Framework (MOF) Membranes)

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15 pages, 4250 KiB

Open AccessArticle

Amidoxime Modified UiO-66@PIM-1 Mixed-Matrix Membranes to Enhance CO₂ Separation and Anti-Aging Performance

by Jiaming Gao, Yongchao Sun, Feifei Kang, Fei Guo, Gaohong He, Hanli Wang, Zhendong Yang, Canghai Ma, Xiaobin Jiang and Wu Xiao

Membranes 2023, 13(9), 781; https://doi.org/10.3390/membranes13090781 - 6 Sep 2023

Cited by 2 | Viewed by 1863

Abstract

Mixed matrix membranes (MMMs) generally have some fatal defects, such as poor compatibility between the two phases leading to non-selective pores. In this work, PIM-1 was chosen as the polymer matrix, and UiO-66 modified with amidoxime (UiO-66-AO) was used as the filler to [...] Read more.

Mixed matrix membranes (MMMs) generally have some fatal defects, such as poor compatibility between the two phases leading to non-selective pores. In this work, PIM-1 was chosen as the polymer matrix, and UiO-66 modified with amidoxime (UiO-66-AO) was used as the filler to prepare the MMMs. In the MMMs, the amino and hydroxyl groups on UO-66-AO form a rich hydrogen bond network with the N and O atoms in the polymer PIM-1 chain to improve the compatibility between the polymer matrix and the filler. In addition, the selective adsorption of CO₂ by the amidoxime group can promote the transport of CO₂ in the membrane, which enhances the gas selectivity. The CO₂ permeability and CO₂/N₂ selectivity of UiO-66-AO@PIM-1 MMMs are increased by 35.2% and 45.2% compared to pure PIM-1 membranes, reaching 7535.5 Barrer and 26.9, surpassing the Robeson Upper Bound (2008) and close to the 2019 Upper Bound. After 38 days of the aging experiment, the CO₂ permeability is approximately 74% of the original. The results show that the addition of UiO-66-AO has an obvious effect on improving the aging properties of the membrane. The UiO-66-AO@PIM-1 MMMs have a bright prospect for CO₂ separation in the future. Full article

(This article belongs to the Special Issue Fabrication, Characterization and Application of Organic/Inorganic Film Membranes and Advanced Materials (Volume III))

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15 pages, 5101 KiB

Open AccessArticle

Wetting-Based Comparison of Ag, Carbon Black, and MoS₂ Composite Membranes for Photothermal Membrane Distillation

by Tarik Eljaddi and Corinne Cabassud

Membranes 2023, 13(9), 780; https://doi.org/10.3390/membranes13090780 - 4 Sep 2023

Cited by 2 | Viewed by 1401

Abstract

Photothermal membrane distillation is a new-generation desalination process that can take advantage of the ability of specific materials to convert solar energy to heat at the membrane surface and thus to overcome temperature polarization. The development of appropriate photothermal membranes is challenging because [...] Read more.

Photothermal membrane distillation is a new-generation desalination process that can take advantage of the ability of specific materials to convert solar energy to heat at the membrane surface and thus to overcome temperature polarization. The development of appropriate photothermal membranes is challenging because many criteria need to be considered, including light to heat conversion, permeability and low wetting, and fouling, as well as cost. Based on our experience with wetting characterization, this study compares photothermal membranes prepared using different well-known or promising materials, i.e., silver nanoparticles (Ag NPs), carbon black, and molybdenum disulfide (MoS₂), in terms of their structural properties, permeability, wettability, and wetting. Accordingly, membranes with different proportions of photothermal NPs are prepared and fully characterized in this study. Wetting is investigated using the detection of dissolved tracer intrusion (DDTI) method following membrane distillation operations with saline solutions. The advantages of MoS₂ and carbon black-based photothermal membranes in comparison with polyvinylidene difluoride (PVDF) membranes include both a permeability increase and a less severe wetting mechanism, with lower wetting indicators in the short term. These materials are also much cheaper than Ag NPs, having higher permeabilities and presenting less severe wetting mechanisms. Full article

(This article belongs to the Special Issue 2D Materials for Membrane Distillation)

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4 pages, 220 KiB

Open AccessEditorial

Recent Studies of Membranes for Liquids Separation and Water Treatment

by Mohammadamin Ezazi, M. M. Quazi and Hossein Taheri

Membranes 2023, 13(9), 779; https://doi.org/10.3390/membranes13090779 - 4 Sep 2023

Cited by 1 | Viewed by 1452

Abstract

Rapid urbanization and industrialization in the past decades have resulted in vast amounts of wastewater containing pollutants such as inorganic chemicals, pathogens, pharmaceuticals, plant nutrients, petrochemical products, and microplastics [...] Full article

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

4 pages, 200 KiB

Open AccessEditorial

Separation Techniques and Circular Economy

by Da-Qi Cao

Membranes 2023, 13(9), 778; https://doi.org/10.3390/membranes13090778 - 4 Sep 2023

Cited by 1 | Viewed by 1579

Abstract

Efficient separation techniques play an important role in the process of resource recovery, and these techniques include physical, chemical, physicochemical, and/or biological methods that are selected for their low cost and low energy consumption and for being free of secondary pollution [...] Full article

(This article belongs to the Special Issue Separation Techniques and Circular Economy)

23 pages, 7448 KiB

Open AccessReview

Modified Membranes for Redox Flow Batteries—A Review

by Misgina Tilahun Tsehaye, Ramato Ashu Tufa, Roviel Berhane, Francesco Deboli, Kibrom Alebel Gebru and Svetlozar Velizarov

Membranes 2023, 13(9), 777; https://doi.org/10.3390/membranes13090777 - 1 Sep 2023

Cited by 4 | Viewed by 2902

Abstract

In this review, the state of the art of modified membranes developed and applied for the improved performance of redox flow batteries (RFBs) is presented and critically discussed. The review begins with an introduction to the energy-storing chemical principles and the potential of [...] Read more.

In this review, the state of the art of modified membranes developed and applied for the improved performance of redox flow batteries (RFBs) is presented and critically discussed. The review begins with an introduction to the energy-storing chemical principles and the potential of using RFBs in the energy transition in industrial and transport-related sectors. Commonly used membrane modification techniques are briefly presented and compared next. The recent progress in applying modified membranes in different RFB chemistries is then critically discussed. The relationship between a given membrane modification strategy, corresponding ex situ properties and their impact on battery performance are outlined. It has been demonstrated that further dedicated studies are necessary in order to develop an optimal modification technique, since a modification generally reduces the crossover of redox-active species but, at the same time, leads to an increase in membrane electrical resistance. The feasibility of using alternative advanced modification methods, similar to those employed in water purification applications, needs yet to be evaluated. Additionally, the long-term stability and durability of the modified membranes during cycling in RFBs still must be investigated. The remaining challenges and potential solutions, as well as promising future perspectives, are finally highlighted. Full article

(This article belongs to the Special Issue Surface Modification and Performance Enhancement for Membranes)

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