Membranes

20 pages, 5158 KiB

Open AccessEditor’s ChoiceArticle

Experimental Investigation on the Energy and Exergy Efficiency of the Vacuum Membrane Distillation System with Its Various Configurations

by Abdullah Najib, Turki Mana, Emad Ali, Hany Al-Ansary, Fahad Awjah Almehmadi and Mansour Alhoshan

Membranes 2024, 14(2), 54; https://doi.org/10.3390/membranes14020054 - 13 Feb 2024

Cited by 1 | Viewed by 1713

Abstract

This paper addresses a retrofitting vacuum membrane distillation (VMD) setup to reduce the accumulated pressure inside the permeated side. This modification is necessary to extend the operation of the VMD to extreme operation conditions of higher hot water temperatures. This modification, denoted as [...] Read more.

This paper addresses a retrofitting vacuum membrane distillation (VMD) setup to reduce the accumulated pressure inside the permeated side. This modification is necessary to extend the operation of the VMD to extreme operation conditions of higher hot water temperatures. This modification, denoted as a hybrid configuration, proposes the injection of a cold water stream into the VMD cell without mixing it with the permeate. Energy and exergy efficiency analyses were performed to assess the effectiveness of the hybrid configuration. The performance of the modified system indicated an improvement in terms of permeate flux (J), the gain output ratio (GOR), and the utilitarian exergetic efficiency (η_ex,u), which reach up to two and three times that of the base configuration of the VMD system. However, the exergetic efficiency (η_ex) of the hybrid system showed marginal improvement compared to the base case over the tested range of hot water temperatures. This is because the enhanced vapor production is penalized by excess energy consumption. Moreover, the highest exergy destruction percentages occurred in the operational components (e.g., heater and chillers) which fall in the range of 19.0–68.9%. The exergy destruction percentage in the original components (e.g., the VMD cell and condenser) did not exceed 8.3%. Furthermore, this study indicated that the hybrid configuration requires additional tuning and optimization to perform efficiently over wide operating conditions. Full article

(This article belongs to the Special Issue Applications of Membrane Processes in Desalination, Wastewater Treatment and Resource Recovery)

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13 pages, 9755 KiB

Open AccessArticle

Screen-Printed Carbon Electrode Modified with Carbon Nanotubes and Copper Film as a Simple Tool for Determination of Trace Concentrations of Lead Ions

by Malgorzata Grabarczyk and Agnieszka Wawruch

Membranes 2024, 14(2), 53; https://doi.org/10.3390/membranes14020053 - 12 Feb 2024

Viewed by 1802

Abstract

A copper film-modified, carboxyl-functionalized, and multi-walled carbon nanotube (MWCNT-COOH)-modified screen-printed carbon electrode (CuF/MWCNTs/SPCE) was used for lead determination using anodic stripping voltammetry. The main parameters were investigated and optimized during the development of the research procedure. The most optimal electrolyte concentrations were determined [...] Read more.

A copper film-modified, carboxyl-functionalized, and multi-walled carbon nanotube (MWCNT-COOH)-modified screen-printed carbon electrode (CuF/MWCNTs/SPCE) was used for lead determination using anodic stripping voltammetry. The main parameters were investigated and optimized during the development of the research procedure. The most optimal electrolyte concentrations were determined to be 0.4 M HCl and 6.3 × 10⁻⁵ M Cu(II). The optimal parameters for voltammetric stripping measurements are as follows: an accumulation potential of −0.7 V; an accumulation time of 120 s; and a pulse amplitude and pulse time of 120 mV and 2 ms, respectively. The effect of surface active substances and humic substances as potential interferents present in aqueous environmental samples was investigated. The validation of the procedure was carried out using certified reference materials, like waste water SPS-WW1 and environmental matrix TM-25.5. In addition, the developed procedure was applied to investigate lead recovery from natural environmental water, such as rivers and lakes. Full article

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27 pages, 7988 KiB

Open AccessEditor’s ChoiceReview

Sustainability in Membrane Technology: Membrane Recycling and Fabrication Using Recycled Waste

by Noman Khalid Khanzada, Raed A. Al-Juboori, Muzamil Khatri, Farah Ejaz Ahmed, Yazan Ibrahim and Nidal Hilal

Membranes 2024, 14(2), 52; https://doi.org/10.3390/membranes14020052 - 12 Feb 2024

Cited by 7 | Viewed by 5729

Abstract

Membrane technology has shown a promising role in combating water scarcity, a globally faced challenge. However, the disposal of end-of-life membrane modules is problematic as the current practices include incineration and landfills as their final fate. In addition, the increase in population and [...] Read more.

Membrane technology has shown a promising role in combating water scarcity, a globally faced challenge. However, the disposal of end-of-life membrane modules is problematic as the current practices include incineration and landfills as their final fate. In addition, the increase in population and lifestyle advancement have significantly enhanced waste generation, thus overwhelming landfills and exacerbating environmental repercussions and resource scarcity. These practices are neither economically nor environmentally sustainable. Recycling membranes and utilizing recycled material for their manufacturing is seen as a potential approach to address the aforementioned challenges. Depending on physiochemical conditions, the end-of-life membrane could be reutilized for similar, upgraded, and downgraded operations, thus extending the membrane lifespan while mitigating the environmental impact that occurred due to their disposal and new membrane preparation for similar purposes. Likewise, using recycled waste such as polystyrene, polyethylene terephthalate, polyvinyl chloride, tire rubber, keratin, and cellulose and their derivates for fabricating the membranes can significantly enhance environmental sustainability. This study advocates for and supports the integration of sustainability concepts into membrane technology by presenting the research carried out in this area and rigorously assessing the achieved progress. The membranes’ recycling and their fabrication utilizing recycled waste materials are of special interest in this work. Furthermore, this study offers guidance for future research endeavors aimed at promoting environmental sustainability. Full article

(This article belongs to the Special Issue Sustainable Polymeric Membrane Preparation and Application)

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21 pages, 5677 KiB

Open AccessEditor’s ChoiceArticle

Field-Scale Testing of a High-Efficiency Membrane Reactor (MR)—Adsorptive Reactor (AR) Process for H₂ Generation and Pre-Combustion CO₂ Capture

by Nicholas Margull, Doug Parsley, Ibubeleye Somiari, Linghao Zhao, Mingyuan Cao, Dimitrios Koumoulis, Paul K. T. Liu, Vasilios I. Manousiouthakis and Theodore T. Tsotsis

Membranes 2024, 14(2), 51; https://doi.org/10.3390/membranes14020051 - 11 Feb 2024

Cited by 2 | Viewed by 2125

Abstract

The study objective was to field-validate the technical feasibility of a membrane- and adsorption-enhanced water gas shift reaction process employing a carbon molecular sieve membrane (CMSM)-based membrane reactor (MR) followed by an adsorptive reactor (AR) for pre-combustion CO₂ capture. The project was [...] Read more.

The study objective was to field-validate the technical feasibility of a membrane- and adsorption-enhanced water gas shift reaction process employing a carbon molecular sieve membrane (CMSM)-based membrane reactor (MR) followed by an adsorptive reactor (AR) for pre-combustion CO₂ capture. The project was carried out in two different phases. In Phase I, the field-scale experimental MR-AR system was designed and constructed, the membranes, and adsorbents were prepared, and the unit was tested with simulated syngas to validate functionality. In Phase II, the unit was installed at the test site, field-tested using real syngas, and a technoeconomic analysis (TEA) of the technology was completed. All project milestones were met. Specifically, (i) high-performance CMSMs were prepared meeting the target H₂ permeance (>1 m³/(m².hbar) and H₂/CO selectivity of >80 at temperatures of up to 300 °C and pressures of up to 25 bar with a <10% performance decline over the testing period; (ii) pelletized adsorbents were prepared for use in relevant conditions (250 °C < T < 450 °C, pressures up to 25 bar) with a working capacity of >2.5 wt.% and an attrition rate of <0.2; (iii) TEA showed that the MR-AR technology met the CO₂ capture goals of 95% CO₂ purity at a cost of electricity (COE) 30% less than baseline approaches. Full article

(This article belongs to the Special Issue Sorption and Transport Phenomena in Inorganic Membranes)

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20 pages, 3230 KiB

Open AccessArticle

Modeling of Integrated Hollow-Fiber Solar-Powered VMD Modules for Desalination for a Better Understanding and Management of Heat Flows

by Gina Alfonso, Stéphanie Laborie and Corinne Cabassud

Membranes 2024, 14(2), 50; https://doi.org/10.3390/membranes14020050 - 11 Feb 2024

Viewed by 1708

Abstract

The direct integration of membrane distillation and solar energy collection in a single module is a promising technology for autonomous seawater desalination in remote regions; however, the modeling and design of such modules are challenging because of the coupling of the radial and [...] Read more.

The direct integration of membrane distillation and solar energy collection in a single module is a promising technology for autonomous seawater desalination in remote regions; however, the modeling and design of such modules are challenging because of the coupling of the radial and longitudinal heat and mass transfers. In a previous study, we provided as a first modeling approach a hollow fiber solar collector vacuum membrane distillation (VMD) module, considering a constant temperature at the shell side and a pure water feed. Here, a full model is developed to describe the coupled effects of the solar collector and a hollow fiber VMD module operating in an outside/in mode with saline water. The model considers all the main phenomena (membrane distillation, temperature and concentration polarization, absorption of solar radiation and energy balances over the solar collector, radial and longitudinal heat and mass transfer, seawater properties, and more than 30 variables). Applied to simulate the behavior of a semi-industrial-scale module, it allows the influence of solar radiation on the performance/limits of the integrated module to be discussed based on the radial and longitudinal profiles and heat flows. The model can be used to identify key points in the module design to better utilize solar radiation and manage heat flows. 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, 4456 KiB

Open AccessArticle

Recovery of Isoamyl Alcohol by Graphene Oxide Immobilized Membrane and Air-Sparged Membrane Distillation

by Mitun Chandra Bhoumick, Sumona Paul, Sagar Roy, Benjamin G. Harvey and Somenath Mitra

Membranes 2024, 14(2), 49; https://doi.org/10.3390/membranes14020049 - 10 Feb 2024

Cited by 2 | Viewed by 1889

Abstract

Isoamyl alcohol is an important biomass fermentation product that can be used as a gasoline surrogate, jet fuel precursor, and platform molecule for the synthesis of fine chemicals and pharmaceuticals. This study reports on the use of graphene oxide immobilized membra (GOIMs) for [...] Read more.

Isoamyl alcohol is an important biomass fermentation product that can be used as a gasoline surrogate, jet fuel precursor, and platform molecule for the synthesis of fine chemicals and pharmaceuticals. This study reports on the use of graphene oxide immobilized membra (GOIMs) for the recovery of isoamyl alcohol from an aqueous matrix. The separation was performed using air-sparged membrane distillation (ASMD). In contrast to a conventional PTFE membrane, which exhibited minimal separation, preferential adsorption on graphene oxide within GOIMs resulted in highly selective isoamyl alcohol separation. The separation factor reached 6.7, along with a flux as high as 1.12 kg/m² h. Notably, the overall mass transfer coefficients indicated improvements with a GOIM. Optimization via response surfaces showed curvature effects for the separation factor due to the interaction effects. An empirical model was generated based on regression equations to predict the flux and separation factor. This study demonstrates the potential of GOIMs and ASMD for the efficient recovery of higher alcohols from aqueous solutions, highlighting the practical applications of these techniques for the production of biofuels and bioproducts. Full article

(This article belongs to the Special Issue Advanced Membrane Technology for Biorefining Processes)

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17 pages, 13402 KiB

Open AccessEditor’s ChoiceReview

Roles of a Glycolipid MPIase in Sec-Independent Membrane Protein Insertion

by Kaoru Nomura, Shoko Mori and Keiko Shimamoto

Membranes 2024, 14(2), 48; https://doi.org/10.3390/membranes14020048 - 8 Feb 2024

Cited by 1 | Viewed by 1826

Abstract

Membrane protein integrase (MPIase), an endogenous glycolipid in Escherichia coli (E. coli) membranes, is essential for membrane protein insertion in E. coli. We have examined Sec-independent membrane protein insertion mechanisms facilitated by MPIase using physicochemical analytical techniques, namely solid-state nuclear [...] Read more.

Membrane protein integrase (MPIase), an endogenous glycolipid in Escherichia coli (E. coli) membranes, is essential for membrane protein insertion in E. coli. We have examined Sec-independent membrane protein insertion mechanisms facilitated by MPIase using physicochemical analytical techniques, namely solid-state nuclear magnetic resonance, fluorescence measurements, and surface plasmon resonance. In this review, we outline the physicochemical characteristics of membranes that may affect membrane insertion of proteins. Subsequently, we introduce our results verifying the effects of membrane lipids on insertion and estimate the impact of MPIase. Although MPIase is a minor component of E. coli membranes, it regulates insertion by altering the physicochemical properties of the membrane. In addition, MPIase promotes insertion by interacting with substrate proteins. We propose comprehensive mechanisms for the membrane insertion of proteins involving MPIase, which provide a physicochemical basis for understanding the roles of glycolipids in protein translocation. Full article

(This article belongs to the Special Issue Advanced Research on Structure-Function Relationships of Membrane Proteins, 2nd Edition)

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13 pages, 1288 KiB

Open AccessArticle

Interactions of Galloylated Polyphenols with a Simple Gram-Negative Bacterial Membrane Lipid Model

by Ryan T. Coones, Maarit Karonen, Rebecca J. Green and Richard Frazier

Membranes 2024, 14(2), 47; https://doi.org/10.3390/membranes14020047 - 8 Feb 2024

Viewed by 1817

Abstract

Differential scanning calorimetry (DSC) was used to explore the interactions of isolated polyphenolic compounds, including (-)-epigallocatechin gallate ((-)-EGCg), tellimagrandins I and II (Tel-I and Tel-II), and 1,2,3,4,6-penta-O-galloyl-d-glucose (PGG), with a model Gram-negative bacterial membrane with a view to investigating [...] Read more.

Differential scanning calorimetry (DSC) was used to explore the interactions of isolated polyphenolic compounds, including (-)-epigallocatechin gallate ((-)-EGCg), tellimagrandins I and II (Tel-I and Tel-II), and 1,2,3,4,6-penta-O-galloyl-d-glucose (PGG), with a model Gram-negative bacterial membrane with a view to investigating their antimicrobial properties. The model membranes comprised 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) and 1,2-dipalmitoyl-sn-glycero-3-phospho-(1’-rac-glycerol) (DPPG), fabricated to mimic the domain formation observed in natural membranes, as well as ideally mixed lipid vesicles for the interaction with (-)-EGCg. Polyphenols induced changes in lipid mixing/de-mixing depending on the method of vesicle preparation, as was clearly evidenced by alterations in the lipid transition temperatures. There was a distinct affinity of the polyphenols for the DPPG lipid component, which was attributed to the electrostatic interactions between the polyphenolic galloyl moieties and the lipid headgroups. These interactions were found to operate through either the stabilization of the lipid headgroups by the polyphenols or the insertion of the polyphenols into the membrane itself. Structural attributes of the polyphenols, including the number of galloyl groups, the hydrophobicity quantified by partition coefficients (logP), and structural flexibility, exhibited a correlation with the temperature transitions observed in the DSC measurements. This study furthers our understanding of the intricate interplay between the structural features of polyphenolic compounds and their interactions with model bacterial membrane vesicles towards the exploitation of polyphenols as antimicrobials. Full article

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17 pages, 7218 KiB

Open AccessEditor’s ChoiceArticle

Identification of Membrane Fouling with Greywater Filtration by Porous Membranes: Combined Effect of Membrane Pore Size and Applied Pressure

by Hoseok Jang, Sinu Kang and Jeonghwan Kim

Membranes 2024, 14(2), 46; https://doi.org/10.3390/membranes14020046 - 7 Feb 2024

Cited by 3 | Viewed by 2062

Abstract

Membrane fouling caused by complex greywater synthesized by personal care products and detergents commercially available for household applications was investigated using dead-end microfiltration (MF) and analyzed systematically by a multistage Hermia blocking model as a first attempt. The highest flux decline was associated [...] Read more.

Membrane fouling caused by complex greywater synthesized by personal care products and detergents commercially available for household applications was investigated using dead-end microfiltration (MF) and analyzed systematically by a multistage Hermia blocking model as a first attempt. The highest flux decline was associated with the smallest pore size of the membrane (0.03 μm). This effectiveness was more pronounced at higher applied pressures to the membrane. A cake layer was formed on the membrane consisting mainly of silica particles present as ingredients in greywater. Although organic rejection was low by the porous MF membrane, the organic compound contributed to membrane fouling in the filtration stage. With a 0.03 μm pore size of the membrane, dominant fouling mechanisms were classified into three stages as applied pressure increased, such as complete pore blocking, intermediate pore blocking, and cake layer formation. Specifically, during the early stage of membrane filtration at 1.5 bar, membrane fouling was determined by complete pore blocking in the 0.10 μm pore size of the membrane. However, the later stage of membrane fouling was controlled mainly by intermediate pore blocking. Regardless of the applied pressure, pore constriction or standard blocking played an important role in the fouling rate with a 0.45 μm pore size of the membrane. Our results also support that complex formation can occur due to the concentration of organic and inorganic species present in simulated greywater. Thus, strategic approaches such as periodic, chemically enhanced backwashing need to be developed and tailored to remove both organic and inorganic fouling from MF membranes treating greywater. Full article

(This article belongs to the Special Issue Advanced Membrane Bioreactors for Wastewater Treatment 2nd Edition)

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23 pages, 9180 KiB

Open AccessEditor’s ChoiceArticle

Studying Conformational Properties of Transmembrane Domain of KCNE3 in a Lipid Bilayer Membrane Using Molecular Dynamics Simulations

by Anna Clara Miranda Moura, Isaac K. Asare, Mateo Fernandez Cruz, Antonio Javier Franco Aguado, Kaeleigh Dyan Tuck, Conner C. Campbell, Matthew W. Scheyer, Ikponwmosa Obaseki, Steve Alston, Andrea N. Kravats, Charles R. Sanders, Gary A. Lorigan and Indra D. Sahu

Membranes 2024, 14(2), 45; https://doi.org/10.3390/membranes14020045 - 4 Feb 2024

Cited by 1 | Viewed by 2297

Abstract

KCNE3 is a single-pass integral membrane protein that regulates numerous voltage-gated potassium channel functions such as KCNQ1. Previous solution NMR studies suggested a moderate degree of curved α-helical structure in the transmembrane domain (TMD) of KCNE3 in lyso-myristoylphosphatidylcholine (LMPC) micelles and isotropic bicelles [...] Read more.

KCNE3 is a single-pass integral membrane protein that regulates numerous voltage-gated potassium channel functions such as KCNQ1. Previous solution NMR studies suggested a moderate degree of curved α-helical structure in the transmembrane domain (TMD) of KCNE3 in lyso-myristoylphosphatidylcholine (LMPC) micelles and isotropic bicelles with the residues T71, S74 and G78 situated along the concave face of the curved helix. During the interaction of KCNE3 and KCNQ1, KCNE3 pushes its transmembrane domain against KCNQ1 to lock the voltage sensor in its depolarized conformation. A cryo-EM study of KCNE3 complexed with KCNQ1 in nanodiscs suggested a deviation of the KCNE3 structure from its independent structure in isotropic bicelles. Despite the biological significance of KCNE3 TMD, the conformational properties of KCNE3 are poorly understood. Here, all atom molecular dynamics (MD) simulations were utilized to investigate the conformational dynamics of the transmembrane domain of KCNE3 in a lipid bilayer containing a mixture of POPC and POPG lipids (3:1). Further, the effect of the interaction impairing mutations (V72A, I76A and F68A) on the conformational properties of the KCNE3 TMD in lipid bilayers was investigated. Our MD simulation results suggest that the KCNE3 TMD adopts a nearly linear α helical structural conformation in POPC-POPG lipid bilayers. Additionally, the results showed no significant change in the nearly linear α-helical conformation of KCNE3 TMD in the presence of interaction impairing mutations within the sampled time frame. The KCNE3 TMD is more stable with lower flexibility in comparison to the N-terminal and C-terminal of KCNE3 in lipid bilayers. The overall conformational flexibility of KCNE3 also varies in the presence of the interaction-impairing mutations. The MD simulation data further suggest that the membrane bilayer width is similar for wild-type KCNE3 and KCNE3 containing mutations. The Z-distance measurement data revealed that the TMD residue site A69 is close to the lipid bilayer center, and residue sites S57 and S82 are close to the surfaces of the lipid bilayer membrane for wild-type KCNE3 and KCNE3 containing interaction-impairing mutations. These results agree with earlier KCNE3 biophysical studies. The results of these MD simulations will provide complementary data to the experimental outcomes of KCNE3 to help understand its conformational dynamic properties in a more native lipid bilayer environment. Full article

(This article belongs to the Special Issue Analytical Sciences of/with Bio(mimetic) Membranes (Volume II))

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12 pages, 3285 KiB

Open AccessArticle

A High-Strength Solid Oxide Fuel Cell Supported by an Ordered Porous Cathode Membrane

by Ting Chen, Huilin Zhang, Guozhu Zheng, Qiang Xue, Zuzhi Huang, Yucun Zhou and Shaorong Wang

Membranes 2024, 14(2), 44; https://doi.org/10.3390/membranes14020044 - 4 Feb 2024

Cited by 1 | Viewed by 2083

Abstract

The phase inversion tape casting has been widely used to fabricate open straight porous supports for solid oxide fuel cells (SOFCs), which can offer better gas transmission and minimize the concentration polarization. However, the overall weak strength of the macro-porous structure still limits [...] Read more.

The phase inversion tape casting has been widely used to fabricate open straight porous supports for solid oxide fuel cells (SOFCs), which can offer better gas transmission and minimize the concentration polarization. However, the overall weak strength of the macro-porous structure still limits the applications of these SOFCs. In this work, a novel SOFC supported by an ordered porous cathode membrane with a four-layer configuration containing a finger-like porous 3 mol% yttria- stabilized zirconia (3YSZ)-La_0.8Sr_0.2Co_0.6Fe_0.4O_3−δ (LSCF) catalyst, porous 8 mol% yttria-stabilized zirconia (8YSZ)-LSCF catalyst, and dense 8YSZ porous 8YSZ-NiO catalyst is successfully prepared by the phase inversion tape casting, dip-coating, co-sintering, and impregnation process. The flexural strength of the open straight porous 3YSZ membrane is as high as 131.95 MPa, which meets the requirement for SOFCs. The cathode-supported single cell shows a peak power density of 540 mW cm⁻² at 850 °C using H₂ as the fuel. The degradation mechanism of the SOFC is investigated by the combination of microstructure characterization and distribution of relaxation times (DRT) analysis. Full article

(This article belongs to the Special Issue Membrane-Related Materials for Fuel Cell and/or Battery Applications)

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16 pages, 4363 KiB

Open AccessArticle

Membrane-Associated Ubiquitin Ligase RING Finger Protein 152 Orchestrates Melanogenesis via Tyrosinase Ubiquitination

by Ryota Ueda, Rina Hashimoto, Yuki Fujii, José C. J. M. D. S. Menezes, Hirotaka Takahashi, Hiroyuki Takeda, Tatsuya Sawasaki, Tomonori Motokawa, Kenzo Tokunaga and Hideaki Fujita

Membranes 2024, 14(2), 43; https://doi.org/10.3390/membranes14020043 - 1 Feb 2024

Cited by 1 | Viewed by 2791

Abstract

Lysosomal degradation of tyrosinase, a pivotal enzyme in melanin synthesis, negatively impacts melanogenesis in melanocytes. Nevertheless, the precise molecular mechanisms by which lysosomes target tyrosinase have remained elusive. Here, we identify RING (Really Interesting New Gene) finger protein 152 (RNF152) as a membrane-associated [...] Read more.

Lysosomal degradation of tyrosinase, a pivotal enzyme in melanin synthesis, negatively impacts melanogenesis in melanocytes. Nevertheless, the precise molecular mechanisms by which lysosomes target tyrosinase have remained elusive. Here, we identify RING (Really Interesting New Gene) finger protein 152 (RNF152) as a membrane-associated ubiquitin ligase specifically targeting tyrosinase for the first time, utilizing AlphaScreen technology. We observed that modulating RNF152 levels in B16 cells, either via overexpression or siRNA knockdown, resulted in decreased or increased levels of both tyrosinase and melanin, respectively. Notably, RNF152 and tyrosinase co-localized at the trans-Golgi network (TGN). However, upon treatment with lysosomal inhibitors, both proteins appeared in the lysosomes, indicating that tyrosinase undergoes RNF152-mediated lysosomal degradation. Through ubiquitination assays, we found the indispensable roles of both the RING and transmembrane (TM) domains of RNF152 in facilitating tyrosinase ubiquitination. In summary, our findings underscore RNF152 as a tyrosinase-specific ubiquitin ligase essential for regulating melanogenesis in melanocytes. Full article

(This article belongs to the Collection Feature Papers in Biological Membrane Composition and Structures)

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18 pages, 3389 KiB

Open AccessReview

Preparation, Modification, and Application of Ethylene-Chlorotrifluoroethylene Copolymer Membranes

by Zhangbin Liao, Qian Wang, Qiuyueming Zhou, Zhaoliang Cui, Zhaohui Wang and Enrico Drioli

Membranes 2024, 14(2), 42; https://doi.org/10.3390/membranes14020042 - 1 Feb 2024

Cited by 1 | Viewed by 2097

Abstract

Ethylene-chlorotrifluoroethylene (ECTFE) was first commercialized by DuPont in 1974. Its unique chemical structure gives it high heat resistance, mechanical strength, and corrosion resistance. But also due to these properties, it is difficult to prepare a membrane from it by the nonsolvent-induced phase separation [...] Read more.

Ethylene-chlorotrifluoroethylene (ECTFE) was first commercialized by DuPont in 1974. Its unique chemical structure gives it high heat resistance, mechanical strength, and corrosion resistance. But also due to these properties, it is difficult to prepare a membrane from it by the nonsolvent-induced phase separation (NIPS) method. However, it can be prepared as a microfiltration membrane using the thermally induced phase separation (TIPS) method at certain temperatures and with the selection of suitable solvents, and the use of green solvents is receiving increasing attention from researchers. The surface wettability of ECTFE membranes usually needs to be modified before use to strengthen its performance to meet the application requirements, usually by graft modification and surface oxidation techniques. This paper provides an overview of the structure of ECTFE and its preparation and modification methods, as well as recent advances in its application areas and prospects for the future methods of preparing high-performance ECTFE membranes. Full article

(This article belongs to the Section Polymeric Membranes)

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15 pages, 2348 KiB

Open AccessEditor’s ChoiceArticle

Impact of Concentration Polarization Phenomena on Gas Separation Processes with High-Performance Zeolite Membranes: Experiments vs. Simulations

by Omar Abdul Majid, Margarita Kuznetsova, Christophe Castel, Eric Favre and Rainier Hreiz

Membranes 2024, 14(2), 41; https://doi.org/10.3390/membranes14020041 - 1 Feb 2024

Cited by 2 | Viewed by 2456

Abstract

Polarization phenomena play a key role in membrane separation processes but remain largely unexplored for gas separations, where the mass transfer resistance is most often limited to the membrane. This assumption, which is commonly used today for the simulation of membrane gas separations, [...] Read more.

Polarization phenomena play a key role in membrane separation processes but remain largely unexplored for gas separations, where the mass transfer resistance is most often limited to the membrane. This assumption, which is commonly used today for the simulation of membrane gas separations, has to be reconsidered when high-performance materials, showing a very high permeance and/or selectivity, are used. In this study, a series of steady-state separation performances experimentally obtained on CO₂/CH₄ mixtures with a zeolite membrane are compared to the predictions of a dedicated 1D approach, recently derived and validated through CFD simulations. Polarization effects are shown to generate a significant negative impact on the separation performances, both in terms of the productivity and separation efficiency. The 1D model predictions, based on pure gas permeance data and without any adjustable parameters, are in very good agreement with the experimental data. This fast and efficient modeling approach can easily be implemented in simulation or process synthesis programs for the rigorous evaluation of membrane gas separation processes, when high-performance materials are used. Full article

(This article belongs to the Section Membrane Processing and Engineering)

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10 pages, 4356 KiB

Open AccessArticle

Cinnamic Acid and Caffeic Acid Effects on Gastric Tight Junction Proteins Analyzed in Xenopus laevis Oocytes

by Marie-Luise Vollstädt, Laura Stein, Nora Brunner and Salah Amasheh

Membranes 2024, 14(2), 40; https://doi.org/10.3390/membranes14020040 - 1 Feb 2024

Viewed by 1778

Abstract

Analysis of secondary plant compounds for the development of novel therapies is a common focus of experimental biomedicine. Currently, multiple health-supporting properties of plant-derived molecules are known but still information on many mechanisms is scarce. Cinnamic acid and caffeic acid are two of [...] Read more.

Analysis of secondary plant compounds for the development of novel therapies is a common focus of experimental biomedicine. Currently, multiple health-supporting properties of plant-derived molecules are known but still information on many mechanisms is scarce. Cinnamic acid and caffeic acid are two of the most abundant polyphenols in human dietary fruits and vegetables. In this study, we investigated cinnamic acid and caffeic acid effects on the gastric barrier, which is primarily provided by members of the transmembrane tight junction protein family of claudins. The Xenopus laevis oocyte has been established, in recent years, as a heterologous expression system for analysis of transmembrane tight junction protein interactions, by performing paired oocyte experiments to identify an effect on protein–protein interactions, in vitro. In our current study, human gastric claudin-4, -5, and -18.2. were expressed and detected in the oocyte plasma membrane by freeze fracture electron microscopy and immunoblotting. Oocytes were paired and incubated with 100 µM or 200 µM cinnamic acid or caffeic acid, or Ringer’s solution, respectively. Caffeic acid showed no effect on the contact area strength of paired oocytes but led to an increased contact area size. In contrast, cinnamic acid-incubated paired oocytes revealed a reduced contact area and a strengthening effect on the contact area was identified. These results may indicate that caffeic acid and cinnamic acid both show an effect on gastric barrier integrity via direct effects on tight junction proteins. Full article

(This article belongs to the Special Issue The Xenopus Oocyte: A Tool for Membrane Biology, Second Edition)

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11 pages, 1444 KiB

Open AccessArticle

Inverse pH Gradient-Assay for Facile Characterization of Proton-Antiporters in Xenopus Oocytes

by Zeinu Mussa Belew, Christa Kanstrup, Chengyao Hua, Christoph Crocoll and Hussam Hassan Nour-Eldin

Membranes 2024, 14(2), 39; https://doi.org/10.3390/membranes14020039 - 1 Feb 2024

Viewed by 1885

Abstract

Xenopus oocytes represent one of the most versatile model systems for characterizing the properties of membrane transporters. However, for studying proton-coupled antiporters, the use of Xenopus oocytes has so far been limited to so-called injection-based transport assays. In such assays, where the compound [...] Read more.

Xenopus oocytes represent one of the most versatile model systems for characterizing the properties of membrane transporters. However, for studying proton-coupled antiporters, the use of Xenopus oocytes has so far been limited to so-called injection-based transport assays. In such assays, where the compound is injected directly into the oocytes’ cytosol and transport is detected by monitoring substrate efflux, poor control over internal diffusion and concentration are incompatible with mechanistic characterizations. In this study, we present an inverse pH-gradient transport assay. Herein, an outward-facing proton gradient enables the characterization of proton antiporters via facile import-based transport assays. We describe two approaches for establishing sustained outward-facing proton gradients across the oocyte membrane, namely by applying alkaline external conditions or through surprisingly stable carbonyl cyanide m-chlorophenyl-hydrazone (CCCP)-mediated acidification of the cytosol. Previously, genetic evidence has shown that DTX18 from Arabidopsis thaliana is essential for the deposition of the hydroxycinnamic acid amide p-coumaroylagmatine (coumaroylagmatine) defence compound on the leaf surface. However, direct evidence for its ability to transport coumarol-agmatine has not been provided. Here, using Xenopus oocytes as expression hosts, we demonstrate DTX18’s ability to transport coumaroyl-agmatine via both injection-based and inverse pH-gradient transport assays. Notably, by showing that DTX18 is capable of accumulating its substrate against its concentration gradient, we showcase the compatibility of the latter with mechanistic investigations. Full article

(This article belongs to the Special Issue The Xenopus Oocyte: A Tool for Membrane Biology, Second Edition)

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14 pages, 2316 KiB

Open AccessArticle

A New Approach for Bioremediation of Olive Mill Wastewaters: Combination of Straw Filtration and Nanofiltration

by Francesco Chidichimo, Maria Rita Basile, Carmela Conidi, Giovanni De Filpo, Rosanna Morelli and Alfredo Cassano

Membranes 2024, 14(2), 38; https://doi.org/10.3390/membranes14020038 - 31 Jan 2024

Cited by 1 | Viewed by 1919

Abstract

A combination of straw filtration and nanofiltration was investigated for the first time as a sustainable approach aimed at valorizing olive mill wastewaters (OMWs) within a circular economy strategy. Ground straw filters with different granulometry (120, 250 and 500 μm) were tested in [...] Read more.

A combination of straw filtration and nanofiltration was investigated for the first time as a sustainable approach aimed at valorizing olive mill wastewaters (OMWs) within a circular economy strategy. Ground straw filters with different granulometry (120, 250 and 500 μm) were tested in the first step to clarify the raw wastewater. The 500 μm filter offered the best performance due to a lower exposed surface of the filtering fibers and a shorter filtering time, allowing us to reduce about 70% of the chemical oxygen demand (COD) of the raw wastewater. Three different commercial membranes in a flat-sheet configuration with a molecular weight cut-off (MWCO) in the range 150–500 Da were tested to fractionate the clarified wastewater according to a dead-end configuration. Among the investigated membranes, a polymeric membrane of 500 Da (NFA-12A) exhibited the highest productivity in selected operating conditions (steady-state values of 11.4 L/m² h at 20 bar and 24 ± 2 °C). In addition, flux decays for this membrane were lower than the other two tested membranes, indicating a lower propensity to fouling phenomena. Higher rejections towards total polyphenols and total antioxidant activity (TAA) (76.6% and 73.2%, respectively) were also observed for this membrane. Flavanols and hydroxycinnamic acids were retained by more than 99%. The combination of straw filtration and NF with the NFA-12A membrane allowed us to reduce the COD of raw OMWs up to 97.6%. The retentate fraction of this membrane exhibited a TAA of 18.9 ± 0.7 mM Trolox, supporting its propensity for the development of innovative formulations of interest in food and nutraceutical applications. Full article

(This article belongs to the Section Membrane Applications)

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22 pages, 1495 KiB

Open AccessEditor’s ChoiceReview

Water, Protons, and the Gating of Voltage-Gated Potassium Channels

by Alisher M. Kariev and Michael E. Green

Membranes 2024, 14(2), 37; https://doi.org/10.3390/membranes14020037 - 29 Jan 2024

Cited by 1 | Viewed by 2519

Abstract

Ion channels are ubiquitous throughout all forms of life. Potassium channels are even found in viruses. Every cell must communicate with its surroundings, so all cells have them, and excitable cells, in particular, especially nerve cells, depend on the behavior of these channels. [...] Read more.

Ion channels are ubiquitous throughout all forms of life. Potassium channels are even found in viruses. Every cell must communicate with its surroundings, so all cells have them, and excitable cells, in particular, especially nerve cells, depend on the behavior of these channels. Every channel must be open at the appropriate time, and only then, so that each channel opens in response to the stimulus that tells that channel to open. One set of channels, including those in nerve cells, responds to voltage. There is a standard model for the gating of these channels that has a section of the protein moving in response to the voltage. However, there is evidence that protons are moving, rather than protein. Water is critical as part of the gating process, although it is hard to see how this works in the standard model. Here, we review the extensive evidence of the importance of the role of water and protons in gating these channels. Our principal example, but by no means the only example, will be the K_v1.2 channel. Evidence comes from the effects of D₂O, from mutations in the voltage sensing domain, as well as in the linker between that domain and the gate, and at the gate itself. There is additional evidence from computations, especially quantum calculations. Structural evidence comes from X-ray studies. The hydration of ions is critical in the transfer of ions in constricted spaces, such as the gate region and the pore of a channel; we will see how the structure of the hydrated ion fits with the structure of the channel. In addition, there is macroscopic evidence from osmotic experiments and streaming current measurements. The combined evidence is discussed in the context of a model that emphasizes the role of protons and water in gating these channels. Full article

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

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14 pages, 2961 KiB

Open AccessArticle

Antimicrobial Activity of Polycaprolactone Nanofiber Coated with Lavender and Neem Oil Nanoemulsions against Airborne Bacteria

by Md Mahfuzur Rahman, Hari Kotturi, Sadegh Nikfarjam, Kanika Bhargava, Nagib Ahsan and Morshed Khandaker

Membranes 2024, 14(2), 36; https://doi.org/10.3390/membranes14020036 - 29 Jan 2024

Viewed by 2288

Abstract

The development of efficient, eco-friendly antimicrobial agents for air purification and disinfection addresses public health issues connected to preventing airborne pathogens. Herein, the antimicrobial activity of a nanoemulsion (control, 5%, 10%, and 15%) containing neem and lavender oils with polycaprolactone (PCL) was investigated [...] Read more.

The development of efficient, eco-friendly antimicrobial agents for air purification and disinfection addresses public health issues connected to preventing airborne pathogens. Herein, the antimicrobial activity of a nanoemulsion (control, 5%, 10%, and 15%) containing neem and lavender oils with polycaprolactone (PCL) was investigated against airborne bacteria, including Escherichia coli, Bacillus subtilis, and Staphylococcus aureus. Various parameters such as the physicochemical properties of the nanoemulsion, pH, droplet size, the polydispersity index (PDI), the minimum inhibitory concentration (MIC), the minimum bacterial concentration (MBC), and the color measurement of the emulsion have been evaluated and optimized. Our results showed that the antimicrobial activity of PCL combined with neem and lavender oil was found to be the highest MIC and MBC against all tested bacteria. The droplet sizes for lavender oil are 21.86–115.15 nm, the droplet sizes for neem oil are 23.92–119.15 nm, and their combination is 25.97–50.22 nm. The range of pH and viscosity of nanoemulsions of various concentrations was found to be 5.8 to 6.6 pH and 0.372 to 2.101 cP. This study highlights the potential of nanotechnology in harnessing the antimicrobial properties of natural essential oils, paving the way for innovative and sustainable solutions in the fight against bacterial contamination. Full article

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28 pages, 8824 KiB

Open AccessReview

Employing Atomic Force Microscopy (AFM) for Microscale Investigation of Interfaces and Interactions in Membrane Fouling Processes: New Perspectives and Prospects

by Mohan Wei, Yaozhong Zhang, Yifan Wang, Xiaoping Liu, Xiaoliang Li and Xing Zheng

Membranes 2024, 14(2), 35; https://doi.org/10.3390/membranes14020035 - 27 Jan 2024

Cited by 6 | Viewed by 3156

Abstract

Membrane fouling presents a significant challenge in the treatment of wastewater. Several detection methods have been used to interpret membrane fouling processes. Compared with other analysis and detection methods, atomic force microscopy (AFM) is widely used because of its advantages in liquid-phase in [...] Read more.

Membrane fouling presents a significant challenge in the treatment of wastewater. Several detection methods have been used to interpret membrane fouling processes. Compared with other analysis and detection methods, atomic force microscopy (AFM) is widely used because of its advantages in liquid-phase in situ 3D imaging, ability to measure interactive forces, and mild testing conditions. Although AFM has been widely used in the study of membrane fouling, the current literature has not fully explored its potential. This review aims to uncover and provide a new perspective on the application of AFM technology in future studies on membrane fouling. Initially, a rigorous review was conducted on the morphology, roughness, and interaction forces of AFM in situ characterization of membranes and foulants. Then, the application of AFM in the process of changing membrane fouling factors was reviewed based on its in situ measurement capability, and it was found that changes in ionic conditions, pH, voltage, and even time can cause changes in membrane fouling morphology and forces. Existing membrane fouling models are then discussed, and the role of AFM in predicting and testing these models is presented. Finally, the potential of the improved AFM techniques to be applied in the field of membrane fouling has been underestimated. In this paper, we have fully elucidated the potentials of the improved AFM techniques to be applied in the process of membrane fouling, and we have presented the current challenges and the directions for the future development in an attempt to provide new insights into this field. Full article

(This article belongs to the Collection Feature Papers in Membrane Surface and Interfaces)

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12 pages, 1393 KiB

Open AccessEditor’s ChoiceArticle

Ultra-Stable Inorganic Mesoporous Membranes for Water Purification

by Ralph A. Bauer, Minghui Qiu, Melissa C. Schillo-Armstrong, Matthew T. Snider, Zi Yang, Yi Zhou and Hendrik Verweij

Membranes 2024, 14(2), 34; https://doi.org/10.3390/membranes14020034 - 27 Jan 2024

Cited by 1 | Viewed by 2110

Abstract

Thin, supported inorganic mesoporous membranes are used for the removal of salts, small molecules (PFAS, dyes, and polyanions) and particulate species (oil droplets) from aqueous sources with high flux and selectivity. Nanofiltration membranes can reject simple salts with 80–100% selectivity through a space [...] Read more.

Thin, supported inorganic mesoporous membranes are used for the removal of salts, small molecules (PFAS, dyes, and polyanions) and particulate species (oil droplets) from aqueous sources with high flux and selectivity. Nanofiltration membranes can reject simple salts with 80–100% selectivity through a space charge mechanism. Rejection by size selectivity can be near 100% since the membranes can have a very narrow size distribution. Mesoporous membranes have received particular interest due to their (potential) stability under operational conditions and during defouling operations. More recently, membranes with extreme stability became interesting with the advent of in situ fouling mitigation by means of ultrasound emitted from within the membrane structure. For this reason, we explored the stability of available and new membranes with accelerated lifetime tests in aqueous solutions at various temperatures and pH values. Of the available ceria, titania, and magnetite membranes, none were actually stable under all test conditions. In earlier work, it was established that mesoporous alumina membranes have very poor stability. A new nanofiltration membrane was made of cubic zirconia membranes that exhibited near-perfect stability. A new ultrafiltration membrane was made of amorphous silica that was fully stable in ultrapure water at 80 °C. This work provides details of membrane synthesis, stability characterization and data and their interpretation. Full article

(This article belongs to the Special Issue Latest Research on Pollutants Removal from Aqueous Media by Membrane Processes)

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18 pages, 2910 KiB

Open AccessArticle

Impact of Cleaning on Membrane Performance during Surface Water Treatment: A Hybrid Process with Biological Ion Exchange and Gravity-Driven Membranes

by Yaser Rasouli, Benoit Barbeau, Raphaël Maltais-Tariant, Caroline Boudoux and Dominique Claveau-Mallet

Membranes 2024, 14(2), 33; https://doi.org/10.3390/membranes14020033 - 25 Jan 2024

Viewed by 1896

Abstract

In this study, the hybrid biological ion exchange (BIEX) resin and gravity-driven membrane (GDM) process was employed for the treatment of coloured and turbid river water. The primary objective was to investigate the impact of both physical and chemical cleaning methods on ceramic [...] Read more.

In this study, the hybrid biological ion exchange (BIEX) resin and gravity-driven membrane (GDM) process was employed for the treatment of coloured and turbid river water. The primary objective was to investigate the impact of both physical and chemical cleaning methods on ceramic and polymeric membranes in terms of their stabilised flux, flux recovery after physical/chemical cleaning, and permeate quality. To address these objectives, two types of MF and UF membranes were utilised (M1 = polymeric MF, M2 = polymeric UF, M3 = ceramic UF, and M4 = lab-made ceramic MF). Throughout the extended operation, the resin functioned initially in the primary ion exchange (IEX) region (NOM displacement with pre-charged chloride) and progressed to a secondary IEX stage (NOM displacement with bicarbonate and sulphate), while membrane flux remained stable. Subsequently, physical cleaning involved air/water backwash with two different flows and pressures, and chemical cleaning utilised NaOH at concentrations of 20 and 40 mM, as well as NaOCl at concentrations of 250 and 500 mg Cl₂/L. These processes were carried out to assess flux recovery and identify fouling reversibility. The results indicate an endpoint of 1728 bed volumes (BVs) for the primary IEX region, while the secondary IEX continued up to 6528 BV. At the end of the operation, DOC and UVA₂₅₄ removal in the effluent of the BIEX columns were 68% and 81%, respectively, compared to influent water. This was followed by 30% and 57% DOC and UVA₂₅₄ removal using M4 (ceramic MF). The stabilised flux remained approximately 3.8–5.2 LMH both before and after the cleaning process, suggesting that membrane materials do not play a pivotal role. The mean stabilised flux of polymeric membranes increased after cleaning, whereas that of the ceramics decreased. Enhanced air–water backwash flow and pressure resulted in an increased removal of hydraulic reversible fouling, which was identified as the dominant fouling type. Ceramic membranes exhibited a higher removal of reversible hydraulic fouling than polymeric membranes. Chemical cleaning had a low impact on flux recovery; therefore, we recommend solely employing physical cleaning. Full article

(This article belongs to the Special Issue Sorption and Transport Phenomena in Inorganic Membranes)

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14 pages, 4224 KiB

Open AccessEditor’s ChoiceArticle

Facilitating Water Permeation in Graphene Oxide Membranes via Incorporating Sulfonato Calix[n]arenes

by Yufan Ji, Shurui Dong, Yiping Huang, Changhai Yue, Hao Zhu, Dan Wu and Jing Zhao

Membranes 2024, 14(2), 32; https://doi.org/10.3390/membranes14020032 - 24 Jan 2024

Cited by 1 | Viewed by 1795

Abstract

Graphene oxide (GO) with its atomic thickness and abundant functional groups holds great potential in molecular-scale membrane separation. However, constructing high-speed and highly selective water transport channels within GO membranes remains a key challenge. Herein, sulfonato calix[n]arenes (SCn) molecules with a cavity structure, [...] Read more.

Graphene oxide (GO) with its atomic thickness and abundant functional groups holds great potential in molecular-scale membrane separation. However, constructing high-speed and highly selective water transport channels within GO membranes remains a key challenge. Herein, sulfonato calix[n]arenes (SCn) molecules with a cavity structure, hydrophilic entrance, and hydrophobic wall were incorporated into GO interlayer channels through a layer-by-layer assembly approach to facilitate water permeation in a water/ethanol separation process. The hydrophilic entrance enables preferential access of water molecules to the cavity over ethanol molecules, while the high hydrophobicity of the cavity wall confers low resistance for water diffusion. After incorporating SCn molecules, the membrane shows a remarkable increase in the water/ethanol separation factor from 732 to 1260, while the permeate flux also increases by about 50%. In addition, the strong electrostatic interactions between the building blocks endow the membrane with excellent swelling resistance even under a high water content. This work provides an effective strategy of constructing high-efficiency water transport channels in membrane. Full article

(This article belongs to the Special Issue Graphene Oxide Membrane for Sustainable Energy and Environmental Applications)

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17 pages, 3101 KiB

Open AccessEditor’s ChoiceArticle

Development of a New Affinity Gold Polymer Membrane with Immobilized Protein A

by Tobias Steegmüller, Tim Kratky, Lena Gollwitzer, Sebastian Patrick Schwaminger and Sonja Berensmeier

Membranes 2024, 14(2), 31; https://doi.org/10.3390/membranes14020031 - 24 Jan 2024

Cited by 1 | Viewed by 2111

Abstract

New and highly selective stationary phases for affinity membrane chromatography have the potential to significantly enhance the efficiency and specificity of therapeutic protein purification by reduced mass transfer limitations. This work developed and compared different immobilization strategies for recombinant Protein A ligands to [...] Read more.

New and highly selective stationary phases for affinity membrane chromatography have the potential to significantly enhance the efficiency and specificity of therapeutic protein purification by reduced mass transfer limitations. This work developed and compared different immobilization strategies for recombinant Protein A ligands to a gold-sputtered polymer membrane for antibody separation in terms of functionalization and immobilization success, protein load, and stability. Successful, functionalization was validated via X-ray photoelectron spectroscopy (XPS). Here, a recombinant Protein A ligand was coupled by N-hydroxysuccinimide (NHS)/N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide (EDC) chemistry to carboxy-functionalized, gold-sputtered membranes. We achieved a binding capacity of up to 104 ± 17 mg of the protein ligand per gram of the gold-sputtered membrane. The developed membranes were able to successfully capture and release the monoclonal antibody (mAb) Trastuzumab, as well as antibodies from fresh frozen human blood plasma in both static and dynamic setups. Therefore, they demonstrated successful functionalization and immobilization strategies. The antibody load was tested using bicinchoninic acid (BCA), ultraviolet-visible spectroscopy (UV-vis) measurements, and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The outcome is a fully functional affinity membrane that can be implemented in a variety of different antibody purification processes, eliminating the need for creating individualized strategies for modifying the surface to suit different substrates or conditions. Full article

(This article belongs to the Special Issue Application of Advanced Membrane Materials in Bioseparation)

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25 pages, 3235 KiB

Open AccessEditor’s ChoiceReview

Membrane Separation Technology in Direct Air Capture

by Pavlo Ignatusha, Haiqing Lin, Noe Kapuscinsky, Ludmila Scoles, Weiguo Ma, Bussaraporn Patarachao and Naiying Du

Membranes 2024, 14(2), 30; https://doi.org/10.3390/membranes14020030 - 24 Jan 2024

Cited by 6 | Viewed by 5124

Abstract

Direct air capture (DAC) is an emerging negative CO₂ emission technology that aims to introduce a feasible method for CO₂ capture from the atmosphere. Unlike carbon capture from point sources, which deals with flue gas at high CO₂ concentrations, carbon [...] Read more.

Direct air capture (DAC) is an emerging negative CO₂ emission technology that aims to introduce a feasible method for CO₂ capture from the atmosphere. Unlike carbon capture from point sources, which deals with flue gas at high CO₂ concentrations, carbon capture directly from the atmosphere has proved difficult due to the low CO₂ concentration in ambient air. Current DAC technologies mainly consider sorbent-based systems; however, membrane technology can be considered a promising DAC approach since it provides several advantages, e.g., lower energy and operational costs, less environmental footprint, and more potential for small-scale ubiquitous installations. Several recent advancements in validating the feasibility of highly permeable gas separation membrane fabrication and system design show that membrane-based direct air capture (m-DAC) could be a complementary approach to sorbent-based DAC, e.g., as part of a hybrid system design that incorporates other DAC technologies (e.g., solvent or sorbent-based DAC). In this article, the ongoing research and DAC application attempts via membrane separation have been reviewed. The reported membrane materials that could potentially be used for m-DAC are summarized. In addition, the future direction of m-DAC development is discussed, which could provide perspective and encourage new researchers’ further work in the field of m-DAC. Full article

(This article belongs to the Special Issue Advanced Membrane Materials for CO₂ Capture and Separation)

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21 pages, 1633 KiB

Open AccessEditor’s ChoiceReview

Simultaneous Wastewater Treatment and Resources Recovery by Forward Osmosis Coupled with Microbial Fuel Cell: A Review

by Hengliang Zhang, Liang Duan, Shilong Li, Qiusheng Gao, Mingyue Li, Fei Xing and Yang Zhao

Membranes 2024, 14(2), 29; https://doi.org/10.3390/membranes14020029 - 23 Jan 2024

Cited by 6 | Viewed by 2566

Abstract

Osmotic microbial fuel cells (OsMFCs) with the abilities to simultaneously treat wastewater, produce clean water, and electricity provided a novel approach for the application of microbial fuel cell (MFC) and forward osmosis (FO). This synergistic merging of functions significantly improved the performances of [...] Read more.

Osmotic microbial fuel cells (OsMFCs) with the abilities to simultaneously treat wastewater, produce clean water, and electricity provided a novel approach for the application of microbial fuel cell (MFC) and forward osmosis (FO). This synergistic merging of functions significantly improved the performances of OsMFCs. Nonetheless, despite their promising potential, OsMFCs currently receive inadequate attention in wastewater treatment, water reclamation, and energy recovery. In this review, we delved into the cooperation mechanisms between the MFC and the FO. MFC facilitates the FO process by promoting water flux, reducing reverse solute flux (RSF), and degrading contaminants in the feed solution (FS). Moreover, the water flux based on the FO principle contributed to MFC’s electricity generation capability. Furthermore, we summarized the potential roles of OsMFCs in resource recovery, including nutrient, energy, and water recovery, and identified the key factors, such as configurations, FO membranes, and draw solutions (DS). We prospected the practical applications of OsMFCs in the future, including their capabilities to remove emerging pollutants. Finally, we also highlighted the existing challenges in membrane fouling, system expansion, and RSF. We hope this review serves as a useful guide for the practical implementation of OsMFCs. 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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21 pages, 3425 KiB

Open AccessCommunication

Membrane Separation of Chicken Byproduct Hydrolysate for Up-Concentration of Bioactive Peptides

by Janka Dibdiakova, Josipa Matic, Sileshi Gizachew Wubshet, Wolfgang Uhl, Lelum Duminda Manamperuma, Bjørn Rusten and Eilen Arctander Vik

Membranes 2024, 14(2), 28; https://doi.org/10.3390/membranes14020028 - 23 Jan 2024

Cited by 2 | Viewed by 2112

Abstract

Membrane processes, such as microfiltration, ultrafiltration, and nanofiltration, are increasingly used for various applications in both upstream and downstream processing. Membrane-based processes play a critical role in the field of separation/purification of biotechnological products, including protein production/purification. The possibility of using membranes to [...] Read more.

Membrane processes, such as microfiltration, ultrafiltration, and nanofiltration, are increasingly used for various applications in both upstream and downstream processing. Membrane-based processes play a critical role in the field of separation/purification of biotechnological products, including protein production/purification. The possibility of using membranes to separate peptides from a chicken byproduct hydrolysate and the effect of the performed downstream processing on the DPP-IV dipeptidyl peptidase IV (DPP-IV) inhibitory activity of mechanical deboning chicken residue (MDCR) has been investigated. The chicken byproduct hydrolysate was prepared by enzymatic hydrolysis followed by microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO) separation. Comparing all separation treatments, hydrolysates processed only by MF and UF show the best DPP-IV inhibition (59.5–60.0% at 1 mg/mL and 34.2–40.7% at 0.5 mg/mL). These samples show dose-responsive behavior. Bioactivity was correlated with molecular weight distribution profiles and average molecular weights. The nanofiltration process notably decrease the inhibitory activity, and these permeates show low DPP-IV inhibition (9.5–21.8% at 1 mg/mL and 3.6–12.1% at 0.5 mg/mL). The size-exclusion chromatography–organic carbon detection–organic nitrogen detection (LC–OCD–OND) analysis confirms that NF and RO would retain the bioactive peptides in the concentrate in comparison to MF and UF. Bioactivity was correlated with molecular weight distribution profiles and average molecular weights. Permeates after ultrafiltration show an IC₅₀ value of 0.75 mg/mL, comparable to other potent DPP-IV inhibitors derived from various food sources, and significantly more potent compared to the microfiltration sample, which shows an IC₅₀ value of 1.04 mg/mL. The average molecular weight of the permeates calculated from the SEC chromatograms was 883 g/mol for UF and 1437 g/mol for MF. Of the four membranes studied, the UF membrane shows the best separation properties with respect to maximizing the yield and up-concentration of the bioactive peptides. Overall, UF was demonstrated to be a feasible technology for the removal of the undesired high-molecular-weight substances and up-concentration of small-molecular-weight bioactive peptides from chicken byproduct hydrolysate. These peptides might exhibit biological activity and could offer several health benefits. There is a high potential for the use of bioactive peptides, and more research in this field can lead to promising results that have significant effects in the food and medical industries. Full article

(This article belongs to the Section Membrane Applications)

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21 pages, 17058 KiB

Open AccessArticle

The Resistance of Polyethersulfone Membranes on the Alkaline Cleaning Solutions

by Marek Gryta and Piotr Woźniak

Membranes 2024, 14(2), 27; https://doi.org/10.3390/membranes14020027 - 23 Jan 2024

Cited by 2 | Viewed by 1954

Abstract

Polyethersulfone (PES) is a polymer popularly used to produce ultrafiltration (UF) membranes. PES is relatively hydrophobic; thus, hydrophilic ingredients are added to the membrane matrix to reduce the fouling intensity. Ingredients such as polyvinylpyrrolidone (PVP) reduce the resistance of PES to NaOH solutions. [...] Read more.

Polyethersulfone (PES) is a polymer popularly used to produce ultrafiltration (UF) membranes. PES is relatively hydrophobic; thus, hydrophilic ingredients are added to the membrane matrix to reduce the fouling intensity. Ingredients such as polyvinylpyrrolidone (PVP) reduce the resistance of PES to NaOH solutions. This study investigated the possibility of using PES membranes for the separation of alkaline cleaning solutions. For this purpose, self-made PES membranes and commercial ultrafiltration PES membranes (UE10—10 kDa and UE50—100 kDa) containing PVP additive were used. The membranes were soaked for 18 months in alkaline (pH = 11.3–11.5) solutions of car washing fluids. It has been found that long-term contact with these solutions caused changes in the structure of the surface layer, especially of membranes containing PVP. As a result, the separation of dextran (100–200 kDa) decreased by 30–40% for PES membranes, 30–40% for UE10 and 40–60% for UE50. Despite these changes, the separation efficiency (rejection of COD, NTU and anionic surfactants) of synthetic car wash wastewater (mixture of surfactants and hydrowax) was similar to the results obtained for pristine membranes. Full article

(This article belongs to the Special Issue Advances in Thin-Film Composite Membranes)

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