Membranes

13 pages, 3983 KiB

Open AccessEditor’s ChoiceArticle

Separation and Recycling of Concentrated Heavy Metal Wastewater by Tube Membrane Distillation Integrated with Crystallization

by Xiang-Yang Lou, Zheng Xu, An-Ping Bai, Montserrat Resina-Gallego and Zhong-Guang Ji

Membranes 2020, 10(1), 19; https://doi.org/10.3390/membranes10010019 - 20 Jan 2020

Cited by 18 | Viewed by 3949

Abstract

Tube membrane distillation (MD) integrated with a crystallization method is used in this study for the concurrent productions of pure water and salt crystals from concentrated single and mixed system solutions. The effects of concentrated Zn²⁺ and Ni²⁺ on performance in [...] Read more.

Tube membrane distillation (MD) integrated with a crystallization method is used in this study for the concurrent productions of pure water and salt crystals from concentrated single and mixed system solutions. The effects of concentrated Zn²⁺ and Ni²⁺ on performance in terms of membrane flux, permeate conductivity, crystal recovery rates, and crystal grades are investigated. Preferred crystallization and co-crystallization determinations were performed for mixed solutions. The results revealed that membrane fluxes remained at 2.61 kg·m⁻²·h⁻¹ and showed a sharp decline until the saturation increased to 1.38. Water yield conductivity was below 10 μs·cm⁻¹. High concentrated zinc and nickel did not have a particular effect on the rejection of the membrane process. For the mixed solutions, membrane flux showed a sharp decrease due to the high saturation, while the conductivity of permeate remained below 10 μs·cm⁻¹ during the whole process. Co-crystallization has been proven to be a better method due to the existence of the SO₄²⁻ common-ion effect. Membrane fouling studies have suggested that the membrane has excellent resistance to fouling from highly concentrated solutions. The MD integrated with crystallization proves to be a promising technology for treating highly concentrated heavy metal solutions. Full article

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

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4 pages, 180 KiB

Open AccessEditorial

Acknowledgement to Reviewers of Membranes in 2019

by Membranes Editorial Office

Membranes 2020, 10(1), 18; https://doi.org/10.3390/membranes10010018 - 19 Jan 2020

Cited by 1 | Viewed by 1873

Abstract

The editorial team greatly appreciates the reviewers who have dedicated their considerable time and expertise to the journal’s rigorous editorial process over the past 12 months, regardless of whether the papers are finally published or not [...] Full article

12 pages, 2380 KiB

Open AccessArticle

Production of High Flux Poly(Ether Sulfone) Membrane Using Silica Additive Extracted from Natural Resource

by Sri Mulyati, Syawaliah Muchtar, Mukramah Yusuf, Nasrul Arahman, Sofyana Sofyana, Cut Meurah Rosnelly, Umi Fathanah, Ryosuke Takagi, Hideto Matsuyama, Norazanita Shamsuddin and Muhammad Roil Bilad

Membranes 2020, 10(1), 17; https://doi.org/10.3390/membranes10010017 - 19 Jan 2020

Cited by 16 | Viewed by 3451

Abstract

This paper reports the application of silica derived from natural biomasses of rice husk and bagasse ashes as membrane modifying agents. The modification was conducted on poly(ether sulfone) (PES) membrane by blending the silica into the dope solution. The modification was aimed to [...] Read more.

This paper reports the application of silica derived from natural biomasses of rice husk and bagasse ashes as membrane modifying agents. The modification was conducted on poly(ether sulfone) (PES) membrane by blending the silica into the dope solution. The modification was aimed to improve the structure and hydraulic performance of the resulting PES membrane. The effects of silica addition to the membrane system were evaluated through the analysis of change in chemical structure using ATR-FTIR, surface morphological change using AFM, and surface hydrophilicity using water contact angle measurement. SEM and AFM images show the silica loading significantly affects the membranes morphologies. Silica loading also promotes hydrophilic property as shown by the decrease in water contact angles from 82° to 52–60° due to the presence of polar groups in some residual silica in the membrane matrix. Silica blending also leads to the formation of membranes with higher permeability of up to three folds but lower humic acid rejection (78–62%). The findings indicate the role of silica to enhance the membrane pore size. The ability of membrane to reject humic acid (of 0.8 nm minimum diameter) indicating that the resulting membranes were in between tight ultrafiltration and nanofiltration type. Nonetheless, applying too-high silica concentration decreased the humic acid rejection most likely due to over enlargement of the membrane pore size. Full article

(This article belongs to the Special Issue Membranes for Water Filtration and Treatment)

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13 pages, 1200 KiB

Open AccessEditor’s ChoiceReview

Development and Application of Supported Ionic Liquid Membranes in Microbial Fuel Cell Technology: A Concise Overview

by Péter Bakonyi, László Koók, Tamás Rózsenberszki, Gábor Tóth, Katalin Bélafi-Bakó and Nándor Nemestóthy

Membranes 2020, 10(1), 16; https://doi.org/10.3390/membranes10010016 - 18 Jan 2020

Cited by 31 | Viewed by 4660

Abstract

Membrane separators are key elements of microbial fuel cells (MFCs), especially of those constructed in a dual-chamber configuration. Until now, membranes made of Nafion have been applied the most widely to set-up MFCs. However, there is a broader agreement in the literature that [...] Read more.

Membrane separators are key elements of microbial fuel cells (MFCs), especially of those constructed in a dual-chamber configuration. Until now, membranes made of Nafion have been applied the most widely to set-up MFCs. However, there is a broader agreement in the literature that Nafion is expensive and in many cases, does not meet the actual (mainly mass transfer-specific) requirements demanded by the process and users. Driven by these issues, there has been notable progress in the development of alternative materials for membrane fabrication, among which those relying on the deployment of ionic liquids are emerging. In this review, the background of and recent advances in ionic liquid-containing separators, particularly supported ionic liquid membranes (SILMs), designed for MFC applications are addressed and evaluated. After an assessment of the basic criteria to be fulfilled by membranes in MFCs, experiences with SILMs will be outlined, along with important aspects of transport processes. Finally, a comparison with the literature is presented to elaborate on how MFCs installed with SILM perform relative to similar systems assembled with other, e.g., Nafion, membranes. Full article

(This article belongs to the Special Issue Ionic Liquid-based Materials for Membrane Processes)

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19 pages, 7234 KiB

Open AccessEditor’s ChoiceArticle

Triple-Layer Nanocomposite Membrane Prepared by Electrospinning Based on Modified PES with Carbon Nanotubes for Membrane Distillation Applications

by Mohamed R. Elmarghany, Ahmed H. El-Shazly, Saeid Rajabzadeh, Mohamed S. Salem, Mahmoud A. Shouman, Mohamed Nabil Sabry, Hideto Matsuyama and Norhan Nady

Membranes 2020, 10(1), 15; https://doi.org/10.3390/membranes10010015 - 16 Jan 2020

Cited by 47 | Viewed by 4783

Abstract

In this work, a novel triple-layer nanocomposite membrane prepared with polyethersulfone (PES)/carbon nanotubes (CNTs) as the primary bulk material and poly (vinylidene fluoride-co-hexafluoro propylene) (PcH)/CNTs as the outer and inner surfaces of the membrane by using electrospinning method is introduced. Modified PES with [...] Read more.

In this work, a novel triple-layer nanocomposite membrane prepared with polyethersulfone (PES)/carbon nanotubes (CNTs) as the primary bulk material and poly (vinylidene fluoride-co-hexafluoro propylene) (PcH)/CNTs as the outer and inner surfaces of the membrane by using electrospinning method is introduced. Modified PES with CNTs was chosen as the bulk material of the triple-layer membrane to obtain a high porosity membrane. Both the upper and lower surfaces of the triple-layer membrane were coated with PcH/CNTs using electrospinning to get a triple-layer membrane with high total porosity and noticeable surface hydrophobicity. Combining both characteristics, next to an acceptable bulk hydrophobicity, resulted in a compelling membrane for membrane distillation (MD) applications. The prepared membrane was utilized in a direct contact MD system, and its performance was evaluated in different salt solution concentrations, feed velocities and feed solution temperatures. The results of the prepared membrane in this study were compared to those reported in previously published papers. Based on the evaluated membrane performance, the triple-layer nanocomposite membrane can be considered as a potential alternative with reasonable cost, relative to other MD membranes. Full article

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

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20 pages, 9228 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Systematic Study of the Impact of Pulsed Electric Field Parameters (Pulse/Pause Duration and Frequency) on ED Performances during Acid Whey Treatment

by Guillaume Dufton, Sergey Mikhaylin, Sami Gaaloul and Laurent Bazinet

Membranes 2020, 10(1), 14; https://doi.org/10.3390/membranes10010014 - 11 Jan 2020

Cited by 20 | Viewed by 3080

Abstract

Processing acid whey is still a challenge for the dairy industry due to its high lactic acid and mineral contents. Their removal processes represent a high investment and running cost in addition to significant production of polluting effluents. A previous study showed that [...] Read more.

Processing acid whey is still a challenge for the dairy industry due to its high lactic acid and mineral contents. Their removal processes represent a high investment and running cost in addition to significant production of polluting effluents. A previous study showed that the use of electrodialysis with the application of pulsed electric fields (PEFs) was sufficiently efficient to produce dryable acid whey with reduced scaling issues during the process. In the present work, eight PEF conditions using different pulse/pause durations and frequencies were tested for 1) process optimization and 2) understanding of the underlying mechanisms involved in PEF process improvements. Best results were obtained for PEF conditions (5 s/5 s) and (15 s/15 s) with almost complete scaling mitigation and minimal energy consumption (5.3 ± 0.4 Wh/g of lactic acid vs. 9.33 ± 1.38 Wh/g for continuous current). Longer pause times also led to better divalent ion demineralization at the expense of sodium elimination induced by stronger affinity with the membrane and longer retention times. For the first time, PEF parameters of relatively low frequencies (<1) were studied in sub-limiting current conditions on a complex solution such as acid whey. Full article

(This article belongs to the Special Issue Ion-Exchange Membranes and Processes)

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17 pages, 2878 KiB

Open AccessEditor’s ChoiceArticle

A Novel Cellulose-Based Polymer for Efficient Removal of Methylene Blue

by Diana Gago, Ricardo Chagas, Luísa M. Ferreira, Svetlozar Velizarov and Isabel Coelhoso

Membranes 2020, 10(1), 13; https://doi.org/10.3390/membranes10010013 - 10 Jan 2020

Cited by 30 | Viewed by 5072

Abstract

A novel cellulose-based cross-linked polymer, dicarboxymethyl cellulose (DCMC), has been synthesized and used for methylene blue (MB) removal. Inductively coupled plasma atomic emission spectrometry (ICP-AES), Fourier-transform infrared spectroscopy (FTIR), nitrogen porosimetry, and optical microscopy were employed to characterize the structure of the cellulose-based [...] Read more.

A novel cellulose-based cross-linked polymer, dicarboxymethyl cellulose (DCMC), has been synthesized and used for methylene blue (MB) removal. Inductively coupled plasma atomic emission spectrometry (ICP-AES), Fourier-transform infrared spectroscopy (FTIR), nitrogen porosimetry, and optical microscopy were employed to characterize the structure of the cellulose-based adsorbent. The number of carboxylate groups per gram of polymer (CG) was calculated with sodium content determined by ICP-AES. Systematic equilibrium and kinetic adsorption studies were performed to assess the polymer suitability for dye removal. The effect of pH on its adsorption capacity was also studied and the equilibrium adsorption data was analyzed using Langmuir, Freundlich, and Sips isotherms. At pH = 3, the adsorption isotherms followed the Langmuir model with a maximum adsorption capacity of 887.6 mg/g. At pH = 6.4, the adsorption isotherms produced S-shape curves and were best fitted with the Sips model. The maximum MB uptake increased to 1354.6 mg/g. Pseudo first-order and second-order models were used to fit the kinetic data. A pseudo second-order kinetic model provided the best correlation for the adsorption of MB onto DCMC. Adsorption coupled with membrane filtration achieved 95% methylene blue removal and DCMC can be successfully regenerated and reused in consecutive experiments. Full article

(This article belongs to the Special Issue Membrane Processes and Materials for a Sustainable Bioeconomy)

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11 pages, 1518 KiB

Open AccessArticle

Monitoring the Interfacial Polymerization of Piperazine and Trimesoyl Chloride with Hydrophilic Interlayer or Macromolecular Additive by In Situ FT-IR Spectroscopy

by Xi Yang

Membranes 2020, 10(1), 12; https://doi.org/10.3390/membranes10010012 - 07 Jan 2020

Cited by 18 | Viewed by 5656

Abstract

The interfacial polymerization (IP) of piperazine (PIP) and trimesoyl chloride (TMC) has been extensively utilized to synthesize nanofiltration (NF) membranes. However, it is still a huge challenge to monitor the IP reaction, because of the fast reaction rate and the formed ultra-thin film. [...] Read more.

The interfacial polymerization (IP) of piperazine (PIP) and trimesoyl chloride (TMC) has been extensively utilized to synthesize nanofiltration (NF) membranes. However, it is still a huge challenge to monitor the IP reaction, because of the fast reaction rate and the formed ultra-thin film. Herein, two effective strategies were applied to reduce the IP reaction rate: (1) the introduction of hydrophilic interlayers between the porous substrate and the formed polyamide layer, and (2) the addition of macromolecular additives in the aqueous solution of PIP. As a result, in situ Fourier transform infrared (FT-IR) spectroscopy was firstly used to monitor the IP reaction of PIP/TMC with hydrophilic interlayers or macromolecular additives in the aqueous solution of PIP. Moreover, the formed polyamide layer growth on the substrate was studied in a real-time manner. The in situ FT-IR experimental results confirmed that the IP reaction rates were effectively suppressed and that the formed polyamide thickness was reduced from 138 ± 24 nm to 46 ± 2 nm according to TEM observation. Furthermore, an optimized NF membrane with excellent performance was consequently obtained, which included boosted water permeation of about 141–238 (L/m²·h·MPa) and superior salt rejection of Na₂SO₄ > 98.4%. Full article

(This article belongs to the Special Issue Selected Papers from the 12th Conference of the Aseanian Membrane Society (AMS12))

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12 pages, 5169 KiB

Open AccessArticle

Gas Permeation Property of Silicon Carbide Membranes Synthesized by Counter-Diffusion Chemical Vapor Deposition

by Takayuki Nagano, Koji Sato and Koichi Kawahara

Membranes 2020, 10(1), 11; https://doi.org/10.3390/membranes10010011 - 06 Jan 2020

Cited by 10 | Viewed by 3894

Abstract

An amorphous silicon carbide (SiC) membrane was synthesized by counter-diffusion chemical vapor deposition (CDCVD) using silacyclobutane (SCB) at 788 K. The SiC membrane on a Ni-γ-alumina (Al₂O₃) α-coated Al₂O₃ porous support possessed a H₂ permeance [...] Read more.

An amorphous silicon carbide (SiC) membrane was synthesized by counter-diffusion chemical vapor deposition (CDCVD) using silacyclobutane (SCB) at 788 K. The SiC membrane on a Ni-γ-alumina (Al₂O₃) α-coated Al₂O₃ porous support possessed a H₂ permeance of 1.2 × 10⁻⁷ mol·m⁻²·s⁻¹·Pa⁻¹ and an excellent H₂/CO₂ selectivity of 2600 at 673 K. The intermittent action of H₂ reaction gas supply and vacuum inside porous support was very effective to supply source gas inside mesoporous intermediate layer. A SiC active layer was formed inside the Ni-γ-Al₂O₃ intermediate layer. The thermal expansion coefficient mismatch between the SiC active layer and Ni-γ-Al₂O₃-coated α-Al₂O₃ porous support was eased by the low decomposition temperature of the SiC source and the membrane structure. Full article

(This article belongs to the Special Issue Selected Papers from the 12th Conference of the Aseanian Membrane Society (AMS12))

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12 pages, 2832 KiB

Open AccessArticle

Formation of Microfiltration Membranes from PMP/PIB Blends: Effect of PIB Molecular Weight on Membrane Properties

by Sergey Ilyin, Viktoria Ignatenko, Tatyana Anokhina, Danila Bakhtin, Anna Kostyuk, Evgenia Dmitrieva, Sergey Antonov and Alexey Volkov

Membranes 2020, 10(1), 9; https://doi.org/10.3390/membranes10010009 - 03 Jan 2020

Cited by 5 | Viewed by 4118

Abstract

A series of microfiltration membranes were fabricated by the extraction of polyisobutylene (PIB) from its immiscible blends with polymethylpentene (PMP). Three PIB with different molecular weight of 7.5 × 10⁴ (Oppanol B15), 34 × 10⁴ (Oppanol B50) and 110 × 10 [...] Read more.

A series of microfiltration membranes were fabricated by the extraction of polyisobutylene (PIB) from its immiscible blends with polymethylpentene (PMP). Three PIB with different molecular weight of 7.5 × 10⁴ (Oppanol B15), 34 × 10⁴ (Oppanol B50) and 110 × 10⁴ (Oppanol B100) g/mol, respectively, were used to evaluate the effect of molecular weight on the porous structure and transport properties of resulting PMP-based membranes. To mimic the conditions of 3D printing, the flat-sheet membranes were fabricated by means of melting of mixtures of various PMP and PIB concentrations through the hot rolls at 240

^{\circ}

C followed by a quick cooling. The rheology study of individual components and blends at 240

^{\circ}

C revealed that PIB B50 possessed the most close flow curve to the pure PMP, and their blends demonstrated the lowest viscosity comparing to the compositions made of PIB with other molecular weights (B15 or B100). SEM images of the cross-section PMP membranes after PIB extraction (PMP/PIB = 55/45) showed that the use of PIB B50 allowed obtaining the sponge-like porous structure, whereas the slit-shaped pores were found in the case of PIB B15 and PIB B100. Additionally, PMP/B50 blends demonstrated the optimum combinations of mechanical properties (_str = 9.1 MPa, E = 0.20 GPa), adhesion to steel (_adh = 0.8 kPa) and retention performance (R_{240 nm} = 99%, R_{38 nm} = 39%). The resulting membranes were non- or low-permeable for water if the concentration of PIB B50 in the initial blends was 40 wt.% or lower. The optimal filtration performance was observed in the case of PMP/B50 blends with a ratio of 55/45 (P_water = 1.9 kg/m²hbar, R_{240 nm} = 99%, R_{38 nm} = 39%) and 50/50 (P_water = 1100 kg/m²hbar, R_{240 nm} = 91%, R_{38 nm} = 36%). Full article

(This article belongs to the Special Issue Selected Papers from PERMEA 2019 - Membrane Conference of Visegrad Countries)

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20 pages, 8071 KiB

Open AccessEditor’s ChoiceArticle

Hydrogen Production via Steam Reforming: A Critical Analysis of MR and RMM Technologies

by Giovanni Franchi, Mauro Capocelli, Marcello De Falco, Vincenzo Piemonte and Diego Barba

Membranes 2020, 10(1), 10; https://doi.org/10.3390/membranes10010010 - 03 Jan 2020

Cited by 70 | Viewed by 6411

Abstract

‘Hydrogen as the energy carrier of the future’ has been a topic discussed for decades and is today the subject of a new revival, especially driven by the investments in renewable electricity and the technological efforts done by high-developed industrial powers, such as [...] Read more.

‘Hydrogen as the energy carrier of the future’ has been a topic discussed for decades and is today the subject of a new revival, especially driven by the investments in renewable electricity and the technological efforts done by high-developed industrial powers, such as Northern Europe and Japan. Although hydrogen production from renewable resources is still limited to small scale, local solutions, and R&D projects; steam reforming (SR) of natural gas at industrial scale is the cheapest and most used technology and generates around 8 kg CO₂ per kg H₂. This paper is focused on the process optimization and decarbonization of H₂ production from fossil fuels to promote more efficient approaches based on membrane separation. In this work, two emerging configurations have been compared from the numerical point of view: the membrane reactor (MR) and the reformer and membrane module (RMM), proposed and tested by this research group. The rate of hydrogen production by SR has been calculated according to other literature works, a one-dimensional model has been developed for mass, heat, and momentum balances. For the membrane modules, the rate of hydrogen permeation has been estimated according to mass transfer correlation previously reported by this research group and based on previous experimental tests carried on in the first RMM Pilot Plant. The methane conversion, carbon dioxide yield, temperature, and pressure profile are compared for each configuration: SR, MR, and RMM. By decoupling the reaction and separation section, such as in the RMM, the overall methane conversion can be increased of about 30% improving the efficiency of the system. Full article

(This article belongs to the Special Issue Hydrogen Generation from Renewable Sources via Membrane Reactor Technology)

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23 pages, 5118 KiB

Open AccessArticle

Sorption/Diffusion Contributions to the Gas Permeation Properties of Bi-Soft Segment Polyurethane/Polycaprolactone Membranes for Membrane Blood Oxygenators

by Tiago M. Eusébio, Ana Rita Martins, Gabriela Pon, Mónica Faria, Pedro Morgado, Moisés L. Pinto, Eduardo J. M. Filipe and Maria Norberta de Pinho

Membranes 2020, 10(1), 8; https://doi.org/10.3390/membranes10010008 - 02 Jan 2020

Cited by 8 | Viewed by 4466

Abstract

Due to their high hemocompatibility and gas permeation capacity, bi-soft segment polyurethane/polycaprolactone (PU/PCL) polymers are promising materials for use in membrane blood oxygenators. In this work, both nonporous symmetric and integral asymmetric PU/PCL membranes were synthesized, and the permeation properties of the atmospheric [...] Read more.

Due to their high hemocompatibility and gas permeation capacity, bi-soft segment polyurethane/polycaprolactone (PU/PCL) polymers are promising materials for use in membrane blood oxygenators. In this work, both nonporous symmetric and integral asymmetric PU/PCL membranes were synthesized, and the permeation properties of the atmospheric gases N₂, O₂, and CO₂ through these membranes were experimentally determined using a new custom-built gas permeation apparatus. Permeate pressure vs. time curves were obtained at 37.0 °C and gas feed pressures up to 5 bar. Fluxes, permeances, and permeability coefficients were determined from the steady-state part of the curves, and the diffusion and sorption coefficients were estimated from the analysis of the transient state using the time-lag method. Independent measurements of the sorption coefficients of the three gases were performed, under equilibrium conditions, in order to validate the new setup and procedure. This work shows that the gas sorption in the PU/PCL polymers is the dominant factor for the permeation properties of the atmospheric gases in these membranes. Full article

(This article belongs to the Special Issue Functional Membranes for Biomedical and Environmental Applications)

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28 pages, 3161 KiB

Open AccessEditor’s ChoiceReview

Design of Monovalent Ion Selective Membranes for Reducing the Impacts of Multivalent Ions in Reverse Electrodialysis

by Abreham Tesfaye Besha, Misgina Tilahun Tsehaye, David Aili, Wenjuan Zhang and Ramato Ashu Tufa

Membranes 2020, 10(1), 7; https://doi.org/10.3390/membranes10010007 - 31 Dec 2019

Cited by 57 | Viewed by 7786

Abstract

Reverse electrodialysis (RED) represents one of the most promising membrane-based technologies for clean and renewable energy production from mixing water solutions. However, the presence of multivalent ions in natural water drastically reduces system performance, in particular, the open-circuit voltage (OCV) and the output [...] Read more.

Reverse electrodialysis (RED) represents one of the most promising membrane-based technologies for clean and renewable energy production from mixing water solutions. However, the presence of multivalent ions in natural water drastically reduces system performance, in particular, the open-circuit voltage (OCV) and the output power. This effect is largely described by the “uphill transport” phenomenon, in which multivalent ions are transported against the concentration gradient. In this work, recent advances in the investigation of the impact of multivalent ions on power generation by RED are systematically reviewed along with possible strategies to overcome this challenge. In particular, the use of monovalent ion-selective membranes represents a promising alternative to reduce the negative impact of multivalent ions given the availability of low-cost materials and an easy route of membrane synthesis. A thorough assessment of the materials and methodologies used to prepare monovalent selective ion exchange membranes (both cation and anion exchange membranes) for applications in (reverse) electrodialysis is performed. Moreover, transport mechanisms under conditions of extreme salinity gradient are analyzed and compared for a better understanding of the design criteria. The ultimate goal of the present work is to propose a prospective research direction on the development of new membrane materials for effective implementation of RED under natural feed conditions. Full article

(This article belongs to the Special Issue Membranes for Electrolysis, Fuel Cells and Batteries)

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14 pages, 2316 KiB

Open AccessArticle

Effect of Humidity on CO₂/N₂ and CO₂/CH₄ Separation Using Novel Robust Mixed Matrix Composite Hollow Fiber Membranes: Experimental and Model Evaluation

by Clara Casado-Coterillo, Ana Fernández-Barquín and Angel Irabien

Membranes 2020, 10(1), 6; https://doi.org/10.3390/membranes10010006 - 30 Dec 2019

Cited by 16 | Viewed by 3782

Abstract

In this work, the performance of new robust mixed matrix composite hollow fiber (MMCHF) membranes with a different selective layer composition is evaluated in the absence and presence of water vapor in CO₂/N₂ and CO₂/CH₄ separation. The [...] Read more.

In this work, the performance of new robust mixed matrix composite hollow fiber (MMCHF) membranes with a different selective layer composition is evaluated in the absence and presence of water vapor in CO₂/N₂ and CO₂/CH₄ separation. The selective layer of these membranes is made of highly permeable hydrophobic poly(trimethyl-1-silylpropine) (PTMSP) and hydrophilic chitosan-ionic liquid (IL-CS) hybrid matrices, respectively, filled with hydrophilic zeolite 4A particles in the first case and HKUST-1 nanoparticles in the second, coated over compatible supports. The effect of water vapor in the feed or using a commercial hydrophobic PDMSXA-10 HF membrane has also been studied for comparison. Mixed gas separation experiments were performed at values of 0 and 50% relative humidity (RH) in the feed and varying CO₂ concentration in N₂ and CH₄, respectively. The performance has been validated by a simple mathematical model considering the effect of temperature and relative humidity on membrane permeability. Full article

(This article belongs to the Special Issue Functional Membranes for Biomedical and Environmental Applications)

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17 pages, 3126 KiB

Open AccessArticle

Purification of Sucrose in Sugar Beet Molasses by Utilizing Ceramic Nanofiltration and Ultrafiltration Membranes

by Mikael Sjölin, Johan Thuvander, Ola Wallberg and Frank Lipnizki

Membranes 2020, 10(1), 5; https://doi.org/10.3390/membranes10010005 - 27 Dec 2019

Cited by 32 | Viewed by 7080

Abstract

Molasses is a sugar mill by-product with low value that today is used primarily for animal feed. However, molasses contains large amounts of sucrose which, if purified, could be used for other purposes. In this study, purification by membrane filtration using ceramic tubular [...] Read more.

Molasses is a sugar mill by-product with low value that today is used primarily for animal feed. However, molasses contains large amounts of sucrose which, if purified, could be used for other purposes. In this study, purification by membrane filtration using ceramic tubular ultrafiltration (UF) and nanofiltration (NF) was examined. NF purifies sucrose by removing small compounds, whereas UF removes larger compounds. Based on our results, high filtration fluxes could be obtained, and it was possible to clean the membranes sufficiently from fouling compounds. Sucrose was separated from other compounds, but the separation efficiency was generally higher with diluted molasses compared with concentrated molasses. This could be explained by more severe fouling when filtering dilute molasses or potentially due to aggregate formations in the molasses as our analysis showed. Overall, this study shows the potential of ceramic UF and NF membranes for sucrose purification from molasses. Full article

(This article belongs to the Special Issue EWM 2019: Membranes for a Sustainable Future)

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15 pages, 3325 KiB

Open AccessArticle

Fabrication of Defect-Free P84^® Polyimide Hollow Fiber for Gas Separation: Pathway to Formation of Optimized Structure

by Miren Etxeberria-Benavides, Oguz Karvan, Freek Kapteijn, Jorge Gascon and Oana David

Membranes 2020, 10(1), 4; https://doi.org/10.3390/membranes10010004 - 25 Dec 2019

Cited by 11 | Viewed by 6178

Abstract

The elimination of the additional defect healing post-treatment step in asymmetric hollow fiber manufacturing would result in a significant reduction in membrane production cost. However, obtaining integrally skinned polymeric asymmetric hollow fiber membranes with an ultrathin and defect-free selective layer is quite challenging. [...] Read more.

The elimination of the additional defect healing post-treatment step in asymmetric hollow fiber manufacturing would result in a significant reduction in membrane production cost. However, obtaining integrally skinned polymeric asymmetric hollow fiber membranes with an ultrathin and defect-free selective layer is quite challenging. In this study, P84® asymmetric hollow fiber membranes with a highly thin (~56 nm) defect-free skin were successfully fabricated by fine tuning the dope composition and spinning parameters using volatile additive (tetrahydrofuran, THF) as key parameters. An extensive experimental and theoretical study of the influence of volatile THF addition on the solubility parameter of the N-methylpyrrolidone/THF solvent mixture was performed. Although THF itself is not a solvent for P84®, in a mixture with a good solvent for the polymer, like N-Methyl-2-pyrrolidone (NMP), it can be dissolved at high THF concentrations (NMP/THF ratio > 0.52). The as-spun fibers had a reproducible ideal CO₂/N₂ selectivity of 40, and a CO₂ permeance of 23 GPU at 35 °C. The fiber production can be scaled-up with retention of the selectivity. Full article

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

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15 pages, 3035 KiB

Open AccessArticle

The Role of Humic Acid, PP Beads, and pH with Water Backwashing in a Hybrid Water Treatment of Multichannel Alumina Microfiltration and PP Beads

by Sungju Hwang, Yooju Lee and Jin Yong Park

Membranes 2020, 10(1), 3; https://doi.org/10.3390/membranes10010003 - 25 Dec 2019

Cited by 3 | Viewed by 2745

Abstract

Photooxidation oxidizes most organic compounds by mineralizing them to small inorganic molecules. In this study, the effects of dissolved organic matter (DOM), pH, and polypropylene (PP) beads concentration on membrane fouling were investigated in a hybrid water treatment process consisting of seven-channel alumina [...] Read more.

Photooxidation oxidizes most organic compounds by mineralizing them to small inorganic molecules. In this study, the effects of dissolved organic matter (DOM), pH, and polypropylene (PP) beads concentration on membrane fouling were investigated in a hybrid water treatment process consisting of seven-channel alumina microfiltration (pore size 1.0 μm) and pure PP beads water backwashing with UV irradiation for photooxidation. The synthetic feed was prepared with humic acid and kaolin and flowed inside the microfiltration (MF) membrane. The permeate contacted the PP beads fluidized in the gap of the membrane and module with outside UV irradiation. Membrane fouling resistance (R_f) increased dramatically with an increase in the concentration of humic acid (HA) from 6 mg/L to 8 mg/L. The treatment efficiency of DOM increased dramatically, from 14.3% to 49.7%, with an increase in the concentration of HA. The R_f decreased with an increase of PP beads concentration. However, maximum permeate volume (V_T) was acquired at 5 g/L of PP beads. The maximal treatment efficiency of DOM was 51.3% at 40 g/L of PP beads. The R_f increased with an increase in the pH of feed, and the maximum V_T was acquired at a pH of 5. The maximal treatment efficiency of DOM was 52.5% at pH 9. Full article

(This article belongs to the Special Issue Selected Papers from the 12th Conference of the Aseanian Membrane Society (AMS12))

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27 pages, 17685 KiB

Open AccessEditor’s ChoiceArticle

Polysulfone Membranes Embedded with Halloysites Nanotubes: Preparation and Properties

by Nagla Kamal, Viktor Kochkodan, Atef Zekri and Said Ahzi

Membranes 2020, 10(1), 2; https://doi.org/10.3390/membranes10010002 - 25 Dec 2019

Cited by 33 | Viewed by 5893

Abstract

In the present study, nanocomposite ultrafiltration membranes were prepared by incorporating nanotubes clay halloysite (HNTs) into polysulfone (PSF) and PSF/polyvinylpyrrolidone (PVP) dope solutions followed by membrane casting using phase inversion method. Characterization of HNTs were conducted using scanning electron microscopy (SEM), transmission electron [...] Read more.

In the present study, nanocomposite ultrafiltration membranes were prepared by incorporating nanotubes clay halloysite (HNTs) into polysulfone (PSF) and PSF/polyvinylpyrrolidone (PVP) dope solutions followed by membrane casting using phase inversion method. Characterization of HNTs were conducted using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and thermogravimetric (TGA) analysis. The pore structure, morphology, hydrophilicity and mechanical properties of the composite membranes were characterized by using SEM, water contact angle (WCA) measurements, and dynamic mechanical analysis. It was shown that the incorporation of HNTs enhanced hydrophilicity and mechanical properties of the prepared PSF membranes. Compared to the pristine PSF membrane, results show that the total porosity and pore size of PSF/HNTs composite membranes increased when HNTs loadings were more than 0.5 wt % and 1.0 wt %, respectively. These findings correlate well with changes in water flux of the prepared membranes. It was observed that HNTs were homogenously dispersed within the PSF membrane matrix at HNTs content of 0.1 to 0.5 wt % and the PSF/HNTs membranes prepared by incorporating 0.2 wt % HNTs loading possess the optimal mechanical properties in terms of elastic modulus and yield stress. In the case of the PSF/PVP matrix, the optimal mechanical properties were obtained with 0.3 wt % of HNTs because PVP enhances the HNTs distribution. Results of bovine serum albumin (BSA) filtration tests indicated that PSF/0.2 wt % HNTs membrane exhibited high BSA rejection and notable anti-fouling properties. Full article

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

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12 pages, 1448 KiB

Open AccessArticle

Affinity Membranes and Monoliths for Protein Purification

by Eleonora Lalli, Jouciane S. Silva, Cristiana Boi and Giulio C. Sarti

Membranes 2020, 10(1), 1; https://doi.org/10.3390/membranes10010001 - 24 Dec 2019

Cited by 24 | Viewed by 5585

Abstract

Affinity capture represents an important step in downstream processing of proteins and it is conventionally performed through a chromatographic process. The performance of this step highly depends on the type of matrix employed. In particular, resin beads and convective materials, such as membranes [...] Read more.

Affinity capture represents an important step in downstream processing of proteins and it is conventionally performed through a chromatographic process. The performance of this step highly depends on the type of matrix employed. In particular, resin beads and convective materials, such as membranes and monoliths, are the commonly available supports. The present work deals with non-competitive binding of bovine serum albumin (BSA) on different chromatographic media functionalized with Cibacron Blue F3GA (CB). The aim is to set up the development of the purification process starting from the lab-scale characterization of a commercially available CB resin, regenerated cellulose membranes and polymeric monoliths, functionalized with CB to identify the best option. The performance of the three different chromatographic media is evaluated in terms of BSA binding capacity and productivity. The experimental investigation shows promising results for regenerated cellulose membranes and monoliths, whose performance are comparable with those of the packed column tested. It was demonstrated that the capacity of convective stationary phases does not depend on flow rate, in the range investigated, and that the productivity that can be achieved with membranes is 10 to 20 times higher depending on the initial BSA concentration value, and with monoliths it is approximately twice that of beads, at the same superficial velocity. Full article

(This article belongs to the Special Issue Membrane Chromatography for Biomolecules Purification)

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Membranes, Volume 10, Issue 1 (January 2020) – 19 articles

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