Membranes

11 pages, 4961 KiB

Open AccessArticle

Enhancing the Separation Performance of Cellulose Membranes Fabricated from 1-Ethyl-3-methylimidazolium Acetate by Introducing Acetone as a Co-Solvent

by Luying Chen, Dooli Kim and Wiebe M. de Vos

Membranes 2024, 14(9), 202; https://doi.org/10.3390/membranes14090202 - 23 Sep 2024

Viewed by 822

Abstract

Cellulose, a sustainable raw material, holds great promise as an ideal candidate for membrane materials. In this work, we focused on establishing a low-cost route for producing cellulose microfiltration membranes by adopting a co-solvent system comprising the ionic liquid 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc) and [...] Read more.

Cellulose, a sustainable raw material, holds great promise as an ideal candidate for membrane materials. In this work, we focused on establishing a low-cost route for producing cellulose microfiltration membranes by adopting a co-solvent system comprising the ionic liquid 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc) and acetone. The introduction of acetone as a co-solvent into the casting solution allowed control over the viscosity, thereby significantly enhancing the morphologies and filtration performances of the resulting cellulose membranes. Indeed, applying this co-solvent allowed the water permeability to be significantly increased, while maintaining high rejections. Furthermore, the prepared cellulose membrane demonstrated excellent fouling resistance behavior and flux recovery behavior during a challenging oil-in-water emulsion filtration. These results highlight a promising approach to fabricate high-performance cellulose membranes. Full article

(This article belongs to the Section Membrane Fabrication and Characterization)

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29 pages, 15317 KiB

Open AccessReview

Controllable Design of Polyamide Composite Membrane Separation Layer Structures via Metal–Organic Frameworks: A Review

by Yanjun Jia, Xiaowen Huo, Lu Gao, Wei Shao and Na Chang

Membranes 2024, 14(9), 201; https://doi.org/10.3390/membranes14090201 - 21 Sep 2024

Viewed by 946

Abstract

Optimizing the structure of the polyamide (PA) layer to improve the separation performance of PA thin-film composite (TFC) membranes has always been a hot topic in the field of membrane preparation. As novel crystalline materials with high porosity, multi-functional groups, and good compatibility [...] Read more.

Optimizing the structure of the polyamide (PA) layer to improve the separation performance of PA thin-film composite (TFC) membranes has always been a hot topic in the field of membrane preparation. As novel crystalline materials with high porosity, multi-functional groups, and good compatibility with membrane substrate, metal–organic frameworks (MOFs) have been introduced in the past decade for the modification of the PA structure in order to break through the separation trade-off between permeability and selectivity. This review begins by summarizing the recent progress in the control of MOF-based thin-film nanocomposite (TFN) membrane structures. The review also covers different strategies used for preparing TFN membranes. Additionally, it discusses the mechanisms behind how these strategies regulate the structure and properties of PA. Finally, the design of a competent MOF material that is suitable to reach the requirements for the fabrication of TFN membranes is also discussed. The aim of this paper is to provide key insights into the precise control of TFN-PA structures based on MOFs. Full article

(This article belongs to the Section Membrane Fabrication and Characterization)

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19 pages, 3248 KiB

Open AccessArticle

On the Temporal Evolution of Key Hemofilter Parameters—In Vitro Study under Co-Current Flow

by Anastasios J. Karabelas, Alexandra Moschona and Konstantinos Merenidis

Membranes 2024, 14(9), 200; https://doi.org/10.3390/membranes14090200 - 21 Sep 2024

Viewed by 714

Abstract

Effective permeability K_P, the ultrafiltration coefficient (K_UF), the sieving coefficient (SC), and the loss/permeation of proteins (primarily albumin) are key parameters/specifications characterizing hemofilter (HF) performance. However, there are uncertainties regarding their determination. This work aims (a) to demonstrate that [...] Read more.

Effective permeability K_P, the ultrafiltration coefficient (K_UF), the sieving coefficient (SC), and the loss/permeation of proteins (primarily albumin) are key parameters/specifications characterizing hemofilter (HF) performance. However, there are uncertainties regarding their determination. This work aims (a) to demonstrate that the co-current flow (of blood and dialysate) can lead to beneficial unidirectional filtration (from blood/plasma to dialysate) under a fairly uniform local trans-membrane pressure (TMP), unlike the presently employed counter-current flow; (b) to study the temporal evolution of key HF performance parameters under co-current flow, particularly during the important early stage of hemocatharsis (HC). Experiments with human plasma and BSA solutions in co-current flow mode (for which a fluid mechanical model is developed) show a fairly uniform local/axial TMP, which also improves the local/axial uniformity of protein membrane fouling, particularly under (currently favored) high convective flux operation. Due to incipient membrane fouling, a significant temporal variability/decline in the effective K_P is observed, and, in turn, of other parameters (i.e., the Kuf, SC, and permeation/mass flux M_m for albumin and total proteins). A satisfactory correlation of the albumin/protein mass flux M_m with permeability K_P is obtained, indicating strong inter-dependence. In conclusion, co-current flow, allowing for a fair local TMP axial uniformity, enables the acquisition of accurate/representative data on the evolution of HF parameters, facilitating their interpretation and correlation. The new results provide a basis for exploring the clinical application of the co-current flow. Full article

(This article belongs to the Section Membrane Applications for Other Areas)

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30 pages, 6040 KiB

Open AccessArticle

A Novel Modeling Optimization Approach for a Seven-Channel Titania Ceramic Membrane in an Oily Wastewater Filtration System Based on Experimentation, Full Factorial Design, and Machine Learning

by Mohamed Echakouri, Amr Henni and Amgad Salama

Membranes 2024, 14(9), 199; https://doi.org/10.3390/membranes14090199 - 20 Sep 2024

Viewed by 827

Abstract

This comprehensive study looks at how operational conditions affect the performance of a novel seven-channel titania ceramic ultrafiltration membrane for the treatment of produced water. A full factorial design experiment (2³) was conducted to study the effect of the cross-flow operating [...] Read more.

This comprehensive study looks at how operational conditions affect the performance of a novel seven-channel titania ceramic ultrafiltration membrane for the treatment of produced water. A full factorial design experiment (2³) was conducted to study the effect of the cross-flow operating factors on the membrane permeate flux decline and the overall permeate volume. Eleven experimental runs were performed for three important process operating variables: transmembrane pressure (TMP), crossflow velocity (CFV), and filtration time (FT). Steady final membrane fluxes and permeate volumes were recorded for each experimental run. Under the optimized conditions (1.5 bar, 1 m/s, and 2 h), the membrane performance index demonstrated an oil rejection rate of 99%, a flux of 297 L/m²·h (LMH), a 38% overall initial flux decline, and a total permeate volume of 8.14 L. The regression models used for the steady-state membrane permeate flux decline and overall permeate volume led to the highest goodness of fit to the experimental data with a correlation coefficient of 0.999. A Multiple Linear Regression method and an Artificial Neural Network approach were also employed to model the experimental membrane permeate flux decline and analyze the impact of the operating conditions on membrane performance. The predictions of the Gaussian regression and the Levenberg–Marquardt backpropagation method were validated with a determination coefficient of 99% and a Mean Square Error of 0.07. Full article

(This article belongs to the Special Issue Ceramic Membranes for Removal of Emerging Pollutants)

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14 pages, 6935 KiB

Open AccessArticle

Electroless Deposition for Robust and Uniform Copper Nanoparticles on Electrospun Polyacrylonitrile (PAN) Microfiltration Membranes

by Temitope Q. Aminu, Hamid Fattahi Juybari, David M. Warsinger and David F. Bahr

Membranes 2024, 14(9), 198; https://doi.org/10.3390/membranes14090198 - 20 Sep 2024

Viewed by 984

Abstract

Filtration membranes coated in metals such as copper have dramatically improved biofouling resistance and pathogen destruction. However, existing coating methods on polymer membranes impair membrane performance, lack uniformity, and may detach from their substrate, thus contaminating the permeate. To solve these challenges, we [...] Read more.

Filtration membranes coated in metals such as copper have dramatically improved biofouling resistance and pathogen destruction. However, existing coating methods on polymer membranes impair membrane performance, lack uniformity, and may detach from their substrate, thus contaminating the permeate. To solve these challenges, we developed the first electroless deposition protocol to immobilize copper nanoparticles on electrospun polyacrylonitrile (PAN) fibers for the design of antimicrobial membranes. The deposition was facilitated by prior silver seeding. Distinct mats with average fiber diameters of 232 ± 36 nm, 727 ± 148 nm and 1017 ± 80 nm were evaluated for filtration performance. Well-dispersed copper nanoparticles were conformal to the fibers, preserving the open-cell architecture of the membranes. The copper particle sizes ranged from 20 to 140 nm. Infrared spectroscopy revealed the PAN fiber mats’ relative chemical stability/resistance to the copper metallization process. In addition, the classical cyclization of the cyano functional group in PAN was observed. For model polystyrene beads with average sizes of 3 μm, Cu NP–PAN fiber mats had high water flux and separation efficiency with negligible loss of Cu NP from the fibers during flow testing. Fiber size increased flux and somewhat decreased separation efficiency, though the efficiency values were still high. Full article

(This article belongs to the Section Membrane Fabrication and Characterization)

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20 pages, 2711 KiB

Open AccessArticle

Sensitivity and Stability Study of Test Conditions for a 1 kW Proton Exchange Membrane Fuel Cell Stack

by Peng Xu, Yingmin Yi, Weijie Wang, Meng Xie and Yiwei Yuan

Membranes 2024, 14(9), 197; https://doi.org/10.3390/membranes14090197 - 18 Sep 2024

Viewed by 614

Abstract

This study investigates the impact of compression force on stack performance and the effect of testing conditions on sensitivity of stack performance. It explores the variation of assembly force on the pressure distribution at different positions in a 1 kW proton exchange membrane [...] Read more.

This study investigates the impact of compression force on stack performance and the effect of testing conditions on sensitivity of stack performance. It explores the variation of assembly force on the pressure distribution at different positions in a 1 kW proton exchange membrane fuel cell stack. Polarization curves and high-frequency resistance (HFR) changes of the stack were measured under different assembly forces, and the optimal assembly force of the stack was determined using the average single-cell voltage (HFR-free). The sensitivity of testing conditions was optimized, and the optimum test parameters at different current densities were identified within the selected range. Stack stability was tested at different current densities using the optimized test conditions, and the sensitivity of test conditions was verified by the fluctuation amplitude of single cell voltage and internal impedance. Full article

(This article belongs to the Section Membrane Applications for Energy)

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17 pages, 4415 KiB

Open AccessArticle

Reverse Solute Diffusion Enhances Sludge Dewatering in Dead-End Forward Osmosis

by Da-Qi Cao, Shi-Cheng Lei, Hui Liu, Yan Jin, Yun-Feng Wu, Yuehua Cui and Rongling Wu

Membranes 2024, 14(9), 196; https://doi.org/10.3390/membranes14090196 - 18 Sep 2024

Viewed by 775

Abstract

Wastewater treatment plants produce high quantities of excess sludge. However, traditional sludge dewatering technology has high energy consumption and occupies a large area. Dead-end forward osmosis (DEFO) is an efficient and energy-saving deep dewatering technology for sludge. In this study, the reverse osmosis [...] Read more.

Wastewater treatment plants produce high quantities of excess sludge. However, traditional sludge dewatering technology has high energy consumption and occupies a large area. Dead-end forward osmosis (DEFO) is an efficient and energy-saving deep dewatering technology for sludge. In this study, the reverse osmosis of salt ions in the draw solution was used to change the sludge cake structure and further reduce its moisture content in cake by releasing the bound water in cell. Three salts, NaCl, KCl, and CaCl₂, were added to the excess sludge feed solution to explore the roles of the reverse osmosis of draw solutes in DEFO. When the added quantities of NaCl and CaCl₂ were 15 and 10 mM, respectively, the moisture content of the sludge after dewatering decreased from 98.1% to 79.7% and 67.3%, respectively. However, KCl did not improve the sludge dewatering performance because of the “high K and low Na” phenomenon in biological cells. The water flux increased significantly for the binary draw solute involving NaCl and CaCl₂ compared to the single draw solute. The extracellular polymer substances in the sludge changed the structure of the filter cake to improve the formation of water channels and decrease osmosis resistance, resulting in an increase in sludge dewatering efficiency. These findings provide support for improving the sludge dewatering performance of DEFO. Full article

(This article belongs to the Special Issue Membrane Separation and Water Treatment: Modeling and Application)

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14 pages, 7551 KiB

Open AccessArticle

Utilization of Water-Insoluble Carbon Nitride-Phosphotungstic Acid Hybrids in Composite Proton Exchange Membranes

by Xiancan Yuan, Zhongrui Lu, Xiaoyang Jia, Zhuoran Yang, Jian Wang, Xiong Wang, Jun Lin and Shaojian He

Membranes 2024, 14(9), 195; https://doi.org/10.3390/membranes14090195 - 13 Sep 2024

Viewed by 643

Abstract

Phosphotungstic acid (HPW) can retain water in proton exchange membranes to increase proton conductivity; however, its water-soluble nature limits further application. In this work, we combined HPW and graphitic carbon nitride (g-C₃N₄) via sintering to prepare water-insoluble hybrids (HWN), [...] Read more.

Phosphotungstic acid (HPW) can retain water in proton exchange membranes to increase proton conductivity; however, its water-soluble nature limits further application. In this work, we combined HPW and graphitic carbon nitride (g-C₃N₄) via sintering to prepare water-insoluble hybrids (HWN), where HPW was chemically linked to g-C₃N₄ to fix HPW. Then, HWN fillers were added to a sulfonated polyether ether ketone (SPEEK) matrix to prepare composite membranes. The conductivity of the composite membrane with 10 wt% HWN is up to 0.066 S cm⁻¹ at room temperature, which is 53% higher than that of the SPEEK control membrane (0.043 S cm⁻¹). The composite membrane also showed stable proton conductivity after being immersed in water for 2000 h. Therefore, our study demonstrates that preparing water-insoluble nanofillers containing HPW components through sintering is a promising approach. Full article

(This article belongs to the Special Issue New Challenges in Proton Exchange Membrane Fuel Cells)

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12 pages, 1758 KiB

Open AccessCommunication

A Novel Method for Separating Full and Empty Adeno-Associated Viral Capsids Using Ultrafiltration

by Deepraj Sarmah and Scott M. Husson

Membranes 2024, 14(9), 194; https://doi.org/10.3390/membranes14090194 - 12 Sep 2024

Viewed by 1758

Abstract

Adeno-associated viral vectors (AAVs) are the predominant viral vectors used for gene therapy applications. A significant challenge in obtaining effective doses is removing non-therapeutic empty viral capsids lacking DNA cargo. Current methods for separating full (gene-containing) and empty capsids are challenging to scale, [...] Read more.

Adeno-associated viral vectors (AAVs) are the predominant viral vectors used for gene therapy applications. A significant challenge in obtaining effective doses is removing non-therapeutic empty viral capsids lacking DNA cargo. Current methods for separating full (gene-containing) and empty capsids are challenging to scale, produce low product yields, are slow, and are difficult to operationalize for continuous biomanufacturing. This communication demonstrates the feasibility of separating full and empty capsids by ultrafiltration. Separation performance was quantified by measuring the sieving coefficients for full and empty capsids using ELISA, qPCR, and an infectivity assay based on the live cell imaging of green fluorescent protein expression. We demonstrated that polycarbonate track-etched membranes with a pore size of 30 nm selectively permeated empty capsids to full capsids, with a high recovery yield (89%) for full capsids. The average sieving coefficients of full and empty capsids obtained through ELISA/qPCR were calculated as 0.25 and 0.49, indicating that empty capsids were about twice as permeable as full capsids. Establishing ultrafiltration as a viable unit operation for separating full and empty AAV capsids has implications for developing the scale-free continuous purification of AAVs. Full article

(This article belongs to the Special Issue Application of Membrane Materials in Bioseparation and Downstream Processing)

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12 pages, 1544 KiB

Open AccessReview

How Is Bone Regeneration Influenced by Polymer Membranes? Insight into the Histological and Radiological Point of View in the Literature

by Alexandra Papuc, Simion Bran, Marioara Moldovan, Ondine Lucaciu, Gabriel Armencea, Grigore Baciut, Cristian Dinu, Florin Onișor, Winfried Kretschmer and Mihaela Baciut

Membranes 2024, 14(9), 193; https://doi.org/10.3390/membranes14090193 - 11 Sep 2024

Viewed by 811

Abstract

The aim of this study was to analyze published works that investigate the in vivo bone regeneration capacity of polymeric membranes loaded with active substances and growth factors. This scoping review’s purpose was to highlight the histological and radiological interpretation of the locally [...] Read more.

The aim of this study was to analyze published works that investigate the in vivo bone regeneration capacity of polymeric membranes loaded with active substances and growth factors. This scoping review’s purpose was to highlight the histological and radiological interpretation of the locally produced effects of the polymer membranes studied so far. For the selection of the articles, a search was made in the PubMed and ScienceDirect databases, according to the PRISMA algorithm, for research/clinical trial type studies. The search strategy was represented by the formula “((biodegradable scaffolds AND critical bone defect) OR (polymers AND mechanical properties) OR (3Dmaterials AND cytotoxicity) AND bone tissue regeneration)” for the PubMed database and “((biodegradable scaffolds AND polymers) OR (polymers AND critical bone defects) OR (biodegradable scaffolds AND mechanical properties) AND bone tissue regeneration)” for the ScienceDirect database. Ethical approval was not required. Eligibility criteria included eight clinical studies published between 2018 and 2023. Our analysis showed that polymer membranes that met most histopathological criteria also produced the most remarkable results observed radiologically. The top effective scaffolds were those containing active macromolecules released conditionally and staged. The PLGA and polycaprolactone scaffolds were found in this category; they granted a marked increase in bone density and improvement of osteoinduction. But, regardless of the membrane composition, all membranes implanted in created bone defects induced an inflammatory response in the first phase. Full article

(This article belongs to the Section Membrane Applications for Other Areas)

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25 pages, 7108 KiB

Open AccessArticle

Coupling Low-Frequency Ultrasound to a Crossflow Microfiltration Pilot: Effect of Ultrasonic Pulse Application on Sono-Microfiltration of Jackfruit Juice

by Herenia Adilene Miramontes-Escobar, Nicolas Hengl, Manuel Dornier, Efigenia Montalvo-González, Martina Alejandra Chacón-López, Nawel Achir, Fabrice Vaillant and Rosa Isela Ortiz-Basurto

Membranes 2024, 14(9), 192; https://doi.org/10.3390/membranes14090192 - 11 Sep 2024

Viewed by 780

Abstract

To reduce membrane fouling during the processing of highly pulpy fruit juices into clarified beverages, a crossflow Sono-Microfiltration (SMF) system was employed, strategically equipped with an ultrasonic probe for the direct application of low-frequency ultrasound (LFUS) to the juice just before the entrance [...] Read more.

To reduce membrane fouling during the processing of highly pulpy fruit juices into clarified beverages, a crossflow Sono-Microfiltration (SMF) system was employed, strategically equipped with an ultrasonic probe for the direct application of low-frequency ultrasound (LFUS) to the juice just before the entrance to the ceramic membrane. Operating conditions were standardized, and the application of LFUS pulses in both corrective and preventive modes was investigated. The effect of SMF on the physicochemical properties and the total soluble phenol (TSP) content of the clarified juice was also evaluated. The distance of ultrasonic energy irradiation guided the selection of the LFUS probe. Amplitude conditions and ultrasonic pulses were more effective in the preventive mode and did not cause membrane damage, reducing the operation time of jackfruit juice by up to 50% and increasing permeability by up to 81%. The SMF did not alter the physicochemical parameters of the clarified juice, and the measured LFUS energy ranges did not affect the TSP concentration during the process. This study is the first to apply LFUS directly to the feed stream in a pilot-scale crossflow microfiltration system to reduce the fouling of ceramic membranes and maintain bioactive compounds in jackfruit juice. Full article

(This article belongs to the Special Issue Membrane Technologies in Food Industry and Bioprocessing)

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18 pages, 3357 KiB

Open AccessArticle

Integrating Whey Processing: Ultrafiltration, Nanofiltration, and Water Reuse from Diafiltration

by Vandré Barbosa Brião, Juliane Mossmann, Bruna Seguenka, Samarah Graciola and Jeferson Steffanello Piccin

Membranes 2024, 14(9), 191; https://doi.org/10.3390/membranes14090191 - 6 Sep 2024

Viewed by 939

Abstract

This work proposes an integrated production of whey protein concentrate (WPC) and lactose and the recovery of water from diafiltration (DF) steps. Whey protein and lactose can be concentrated using ultrafiltration and nanofiltration, respectively, and both can be purified using DF. However, DF [...] Read more.

This work proposes an integrated production of whey protein concentrate (WPC) and lactose and the recovery of water from diafiltration (DF) steps. Whey protein and lactose can be concentrated using ultrafiltration and nanofiltration, respectively, and both can be purified using DF. However, DF uses three-fold the initial volume of whey. We propose a method to reclaim this water using reverse osmosis and adsorption by activated carbon. We produced WPC with 88% protein and purified lactose (90%), and 66% of the water can be reclaimed as drinking water. Additionally, the reclaimed water was used to produce another batch of WPC, with no decrease in product quality. Water recovery from the whey process is necessary to meet the needs of a dairy refinery. Full article

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

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28 pages, 5406 KiB

Open AccessReview

Research on Reverse Osmosis (RO)/Nanofiltration (NF) Membranes Based on Thin Film Composite (TFC) Structures: Mechanism, Recent Progress and Application

by Huibin Geng, Weihao Zhang, Xiaoxu Zhao, Wei Shao and Haitao Wang

Membranes 2024, 14(9), 190; https://doi.org/10.3390/membranes14090190 - 5 Sep 2024

Viewed by 2400

Abstract

The global shortage of clean water is a major problem, even in water-rich regions. To solve this problem, low-cost and energy-efficient water treatment methods are needed. Membrane separation technology (MST), as a separation method with low energy consumption, low cost, and good separation [...] Read more.

The global shortage of clean water is a major problem, even in water-rich regions. To solve this problem, low-cost and energy-efficient water treatment methods are needed. Membrane separation technology (MST), as a separation method with low energy consumption, low cost, and good separation effect, has been widely used to deal with seawater desalination, resource recovery, industrial wastewater treatment, and other fields. With the continuous progress of scientific and technological innovation and the increasing demand for use, NF/RO membranes based on the TFC structure are constantly being upgraded. This paper presents the recent research progress of NF and RO membranes based on TFC structures and their applications in different fields, especially the formation mechanism and regulation of selective layer structures and the modification methods of selective layers. Our summary provides fundamental insights into the understanding of NF and RO membrane processes and hopefully triggers further thinking on the development of membrane filtration process optimization. Full article

(This article belongs to the Special Issue Design, Characterization and Application of Membrane Filtration Process)

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21 pages, 6605 KiB

Open AccessArticle

Flow Dynamics through a High Swelling Nanofiber Membrane Processed at Different Relative Humidities: A Study on a FexOy/Polyvinyl Alcohol Composite

by Ayelen C. Santos, Alicia Vergara-Rubio, Angel J. Mazocca and Silvia Goyanes

Membranes 2024, 14(9), 189; https://doi.org/10.3390/membranes14090189 - 30 Aug 2024

Viewed by 929

Abstract

Addressing the global problem of polluted water requires sustainable, efficient, and scalable remediation solutions, such as electrospun polyvinyl alcohol (PVA) membranes incorporating specific nanoadsorbents. The retention of contaminants depends on membrane swelling, morphology, and the adsorbent within the nanofiber. This study investigated the [...] Read more.

Addressing the global problem of polluted water requires sustainable, efficient, and scalable remediation solutions, such as electrospun polyvinyl alcohol (PVA) membranes incorporating specific nanoadsorbents. The retention of contaminants depends on membrane swelling, morphology, and the adsorbent within the nanofiber. This study investigated the effect of relative humidity (RH) within the electrospinning chamber on the morphology of the resulting mats and how this affected the flow dynamics depending on whether or not the permeating liquid induced swelling in the membranes. An insolubilized PVA membrane was used as a hydrophilic filter model and a PVA membrane filled with iron oxide nanoparticles (IONPs) as a composite model (PVA + IONPs). The presence of IONPs increases the nanofiber diameter, which decreases when prepared under intermediate RH (IRH). Consequently, the nanofiber configuration, which is critical for filtration tortuosity, is influenced by RH. The initial swelling results in over 60% greater water flux through PVA + IONPs compared to PVA at an equivalent RH. This characterization helps to optimize membrane applications, highlighting that PVA + IONPs exhibit lower permeability values at IRH, indicating improved contaminant retention capabilities. Full article

(This article belongs to the Special Issue Membrane Processes in a Circular Economy: Opportunities and Challenges)

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16 pages, 3727 KiB

Open AccessArticle

A Carrier Phase Ultrafiltration and Backflow Recovery Technique for Purification of Biological Macromolecules

by Raja Ghosh

Membranes 2024, 14(9), 188; https://doi.org/10.3390/membranes14090188 - 30 Aug 2024

Viewed by 924

Abstract

A simple carrier phase based ultrafiltration technique that is akin to liquid chromatography and is suitable for medium-to-large volume sample preparation in the laboratory is discussed in this paper. A membrane module was integrated with a liquid chromatography system in a “plug and [...] Read more.

A simple carrier phase based ultrafiltration technique that is akin to liquid chromatography and is suitable for medium-to-large volume sample preparation in the laboratory is discussed in this paper. A membrane module was integrated with a liquid chromatography system in a “plug and play” mode for ease of sample handling, and recovery of species retained by the membrane. The sample injector and pump were used for feed injection and for driving ultrafiltration, while the sensors and detectors were used for real-time monitoring of the separation process. The concentration of retained species was enriched by utilizing controlled concentration polarization. The recovery of the retained and enriched species was enhanced by backflow of carrier phase through the membrane using appropriate combination of valves. The backflow of carrier phase also cleaned the membrane and limited the extent of membrane fouling. Proof-of-concept of the proposed technique was provided by conducting different types of protein ultrafiltration experiments. The technique was shown to be suitable for carrying out protein fractionation, desalting, buffer exchange and concentration enrichment. Adoption of this approach is likely to make ultrafiltration easier to use for non-specialized users in biological research laboratories. Other advantages include enhanced product recovery, significant reduction in the number of diavolumes of buffer needed for conducting desalting and buffer exchange, minimal membrane fouling and the potential for repeated use of the same module for multiple separation cycles. Full article

(This article belongs to the Section Membrane Applications for Other Areas)

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12 pages, 2579 KiB

Open AccessArticle

Practical Osmotic Agent for High-Degree Pharmaceutical Pre-Concentration by Organic Solvent Forward Osmosis

by Ryoichi Takada, Ryosuke Takagi, Zhaohuan Mai, Atsushi Matsuoka and Hideto Matsuyama

Membranes 2024, 14(9), 187; https://doi.org/10.3390/membranes14090187 - 29 Aug 2024

Viewed by 802

Abstract

Pre-concentration can reduce the total production costs in the pharmaceutical industry. Organic solvent forward osmosis (OSFO) is a suitable pre-concentration method because of its nonthermal nature, low capital cost, and potential for achieving high-degree concentrations. In a previous study, we first demonstrated a [...] Read more.

Pre-concentration can reduce the total production costs in the pharmaceutical industry. Organic solvent forward osmosis (OSFO) is a suitable pre-concentration method because of its nonthermal nature, low capital cost, and potential for achieving high-degree concentrations. In a previous study, we first demonstrated a high-degree OSFO concentration. Sucrose octaacetate (SoA) in MeOH was concentrated to 52 wt% using polyethylene glycol (PEG)-400 as the osmotic agent, but the concentrated solution had a concentration of 17% PEG-400 because of the reverse solute flux. This result does not meet the typical purity standards required for pharmaceutical production, indicating the need to determine a suitable osmotic agent that can be used for practical purposes. This study proposes a practical osmotic agent for OSFO pre-concentration. First, osmotic agents were screened from a practical perspective. Polypropylene glycol (PPG)-400 was selected, owing to its low toxicity, good solubility, and low viscosity. Subsequently, the OSFO concentration was demonstrated using PPG-400 as the osmotic agent. SoA in MeOH was concentrated from 9.4 wt% to 48 wt%. The final feed solution contained only 0.04 wt% PPG-400. This result is the first demonstration of successful pharmaceutical pre-concentration using OSFO that satisfies the typical purity requirement in pharmaceutical production. Full article

(This article belongs to the Topic Advances in Separation Engineering)

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13 pages, 2687 KiB

Open AccessArticle

Tuning the Properties of Polyvinylidene Fluoride/Alkali Lignin Membranes to Develop a Biocatalytic Membrane Reactor for an Organophosphorus Pesticide Degradation

by Serena Regina, Giuseppe Vitola, Rosalinda Mazzei and Lidietta Giorno

Membranes 2024, 14(9), 186; https://doi.org/10.3390/membranes14090186 - 28 Aug 2024

Viewed by 990

Abstract

It has been observed that the immobilization of a phosphotriesterase enzyme (PTE) onto polyvinylidene fluoride (PVDF) membranes significantly decreased the enzyme activity, and this negative effect was attributed to the hydrophobic character of the membrane. The indirect indication of this reason was that [...] Read more.

It has been observed that the immobilization of a phosphotriesterase enzyme (PTE) onto polyvinylidene fluoride (PVDF) membranes significantly decreased the enzyme activity, and this negative effect was attributed to the hydrophobic character of the membrane. The indirect indication of this reason was that the same enzyme immobilized on other membrane materials bearing hydrophilic character showed better performance. In this work, we provide direct evidence of the mechanism by immobilizing a PTE on a PVDF membrane hydrophilized by blending it with alkali lignin (AL). The PTE was immobilized on PVDF membrane by a covalent bond with the same procedure used in earlier studies to attribute changes in enzyme activity solely to the wettability properties (and not to the material chemistry). The activity of the PTE immobilized on the PVDF membrane hydrophilized with AL was 50% higher than that of the enzyme immobilized on the PVDF hydrophobic membrane. Further improvements of the membrane structure tailored for the development of a biocatalytic membrane reactor (BMR) were also promoted. In particular, the performance of the BMR was studied as a function of the thickness of the membrane, which allowed us to modulate the residence time into the enzyme-loaded membrane pores while maintaining the flow rate through the pores at a constant. Full article

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

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11 pages, 2036 KiB

Open AccessArticle

Application of Online Flow Cytometry for Early Biofouling Detection in Reverse Osmosis Membrane Systems

by Laura Pulido Beltran, Johannes S. Vrouwenvelder and Nadia Farhat

Membranes 2024, 14(9), 185; https://doi.org/10.3390/membranes14090185 - 27 Aug 2024

Viewed by 1072

Abstract

Biofouling poses a significant challenge to reverse osmosis (RO) membrane systems, necessitating timely detection for effective control. This study evaluated the efficacy of flow cytometry (FCM) for early biofilm detection in comparison to conventional system performance indicators. Feed channel pressure drop and total [...] Read more.

Biofouling poses a significant challenge to reverse osmosis (RO) membrane systems, necessitating timely detection for effective control. This study evaluated the efficacy of flow cytometry (FCM) for early biofilm detection in comparison to conventional system performance indicators. Feed channel pressure drop and total cell concentration in the Membrane Fouling Simulator (MFS) flowcell cross-flow outlet water were monitored over time as early biofouling indicators. The results demonstrated the potential of increased bacterial cell concentration in cross-flow outlet water as a reliable indicator of biofouling development on the membrane. Water outlet monitoring enabled faster biofouling detection compared to feed channel pressure drop. Membrane autopsy confirmed biofilm presence prior to the pressure drop increase, highlighting the advantage of early detection in implementing corrective measures. Timely intervention reduces operational costs and energy consumption in membrane-based processes. Full article

(This article belongs to the Special Issue New Advances in Membrane Fouling during Water and Wastewater Treatment)

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42 pages, 17901 KiB

Open AccessReview

MXene/Carbon Nanocomposites for Water Treatment

by Aruzhan Keneshbekova, Gaukhar Smagulova, Bayan Kaidar, Aigerim Imash, Akram Ilyanov, Ramazan Kazhdanbekov, Eleonora Yensep and Aidos Lesbayev

Membranes 2024, 14(9), 184; https://doi.org/10.3390/membranes14090184 - 25 Aug 2024

Viewed by 1484

Abstract

One of the most critical problems faced by modern civilization is the depletion of freshwater resources due to their continuous consumption and contamination with different organic and inorganic pollutants. This paper considers the potential of already discovered MXenes in combination with carbon nanomaterials [...] Read more.

One of the most critical problems faced by modern civilization is the depletion of freshwater resources due to their continuous consumption and contamination with different organic and inorganic pollutants. This paper considers the potential of already discovered MXenes in combination with carbon nanomaterials to address this problem. MXene appears to be a highly promising candidate for water purification due to its large surface area and electrochemical activity. However, the problems of swelling, stability, high cost, and scalability need to be overcome. The synthesis methods for MXene and its composites with graphene oxide, carbon nanotubes, carbon nanofibers, and cellulose nanofibers, along with their structure, properties, and mechanisms for removing various pollutants from water, are described. This review discusses the synthesis methods, properties, and mechanisms of water purification using MXene and its composites. It also explores the fundamental aspects of MXene/carbon nanocomposites in various forms, such as membranes, aerogels, and textiles. A comparative analysis of the latest research on this topic shows the progress in this field and the limitations for the practical application of MXene/carbon nanocomposites to solve the problem of drinking water scarcity. Consequently, this review demonstrates the relevance and promise of the material and underscores the importance of further research and development of MXene/carbon nanocomposites to provide effective water treatment solutions. Full article

(This article belongs to the Special Issue Recent Advances in 2D Material-Based Membranes)

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18 pages, 5348 KiB

Open AccessArticle

Simulating the Permeation of Toxic Chemicals through Barrier Materials

by Alex Bicket, Vivian Lau and Jules Thibault

Membranes 2024, 14(9), 183; https://doi.org/10.3390/membranes14090183 - 24 Aug 2024

Viewed by 1004

Abstract

Chemical warfare agents that are liquids with low vapor pressure pose a contact hazard to anyone who encounters them. Personal protective equipment (PPE) is utilized to ensure safe interaction with these agents. A commonly used method to characterize the permeability of PPE towards [...] Read more.

Chemical warfare agents that are liquids with low vapor pressure pose a contact hazard to anyone who encounters them. Personal protective equipment (PPE) is utilized to ensure safe interaction with these agents. A commonly used method to characterize the permeability of PPE towards chemical weapons is to apply droplets of the liquid agent to the surface of the material and measure for chemical breakthrough. However, this method could produce errors in the estimated values of the transport properties. In this paper, we solved numerically the three-dimensional cylindrical Fick’s second law of diffusion for a liquid permeating through a non-porous rubbery membrane to determine the time the permeating species will emerge on the other side of the polymer membrane. Simulations of different amounts of surface area coverage and the geometries of permeate on the membrane surface indicated that incomplete surface area coverage affects the estimation of the transport properties, making the experimentally determined transport properties unsuitable for predictive use. We simulated different permeation values to determine the factors that most influenced the estimation error and if the error was consistent over different permeate–membrane combinations. Finally, a method to correct the experimentally determined permeability is suggested. Full article

(This article belongs to the Section Membrane Applications for Other Areas)

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13 pages, 2700 KiB

Open AccessArticle

New Insights on Y, La, Nd, and Sm Extraction with Bifunctional Ionic Liquid Cyphos IL 104 Incorporated in a Polymer Inclusion Membrane

by Mohamed Malki, Lynda Mitiche, Amar Sahmoune and Clàudia Fontàs

Membranes 2024, 14(9), 182; https://doi.org/10.3390/membranes14090182 - 23 Aug 2024

Viewed by 1301

Abstract

In this study, an ionic liquid-based polymer inclusion membrane (IL-PIM) made of (50% polymer-50% CyphosIL104) was used to extract and separate the rare earth elements (REEs) Y, La, Nd, and Sm in chloride solutions. The effect of extraction time and pH was studied [...] Read more.

In this study, an ionic liquid-based polymer inclusion membrane (IL-PIM) made of (50% polymer-50% CyphosIL104) was used to extract and separate the rare earth elements (REEs) Y, La, Nd, and Sm in chloride solutions. The effect of extraction time and pH was studied to optimize the extraction and separation conditions. The four REEs were effectively extracted at pH 4–5 from both single and mixed metals solutions. However, at pH 2, only Y was extracted. The recovery of the extracted REEs from the loaded PIM was achieved using HNO₃ and H₂SO₄. In the case of La, it was quantitatively back-extracted with H₂SO₄ after a contact time of 1 h, while up to 4 h was necessary to recover 70% of the extracted Y, Sm, and Nd. Extraction isotherms were studied, and the Freundlich isotherm model was the most adequate to describe the interaction between the PIM and the REEs. Finally, the developed PIM was investigated for the extraction of REEs from mixtures containing other metals, which showed great selectivity for the REEs. Full article

(This article belongs to the Section Membrane Applications for Other Areas)

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18 pages, 2713 KiB

Open AccessArticle

Engineering Phosphatidylserine Containing Asymmetric Giant Unilamellar Vesicles

by Jake McDonough, Trevor A. Paratore, Hannah M. Ketelhohn, Bella C. DeCilio, Alonzo H. Ross and Arne Gericke

Membranes 2024, 14(9), 181; https://doi.org/10.3390/membranes14090181 - 23 Aug 2024

Viewed by 1057

Abstract

The plasma membrane lipid distribution is asymmetric, with several anionic lipid species located in its inner leaflet. Among these, phosphatidylserine (PS) plays a crucial role in various important physiological functions. Over the last decade several methods have been developed that allow for the [...] Read more.

The plasma membrane lipid distribution is asymmetric, with several anionic lipid species located in its inner leaflet. Among these, phosphatidylserine (PS) plays a crucial role in various important physiological functions. Over the last decade several methods have been developed that allow for the fabrication of large or giant unilamellar vesicles (GUVs) with an asymmetric lipid composition. Investigating the physicochemical properties of PS in such asymmetric lipid bilayers and studying its interactions with proteins necessitates the reliable fabrication of asymmetric GUVs (aGUVs) with a high degree of asymmetry that exhibit PS in the outer leaflet so that the interaction with peptides and proteins can be studied. Despite progress, achieving aGUVs with well-defined PS asymmetry remains challenging. Recently, a Ca²⁺-initiated hemifusion method has been introduced, utilizing the fusion of symmetric GUVs (sGUVs) with a supported lipid bilayer (SLB) for the fabrication of aGUVs. We extend this approach to create aGUVs with PS in the outer bilayer leaflet. Comparing the degree of asymmetry between aGUVs obtained via Ca²⁺ or Mg²⁺ initiated hemifusion of a phosphatidylcholine (PC) sGUVwith a PC/PS-supported lipid bilayer, we observe for both bivalent cations a significant number of aGUVs with near-complete asymmetry. The degree of asymmetry distribution is narrower for physiological salt conditions than at lower ionic strengths. While Ca²⁺ clusters PS in the SLB, macroscopic domain formation is absent in the presence of Mg²⁺. However, the clustering of PS upon the addition of Ca²⁺ is apparently too slow to have a negative effect on the quality of the obtained aGUVs. We introduce a data filtering method to select aGUVs that are best suited for further investigation. Full article

(This article belongs to the Special Issue Advances in Symmetric and Asymmetric Lipid Membranes)

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Membranes, Volume 14, Issue 9 (September 2024) – 22 articles

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