Membranes

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11 pages, 3361 KiB

Open AccessArticle

Permeation Properties of Ions through Inorganic Silica-Based Membranes

by Junko Yoshiura, Katsunori Ishii, Yuta Saito, Takaya Nagataki, Yuhei Nagataki, Ayumi Ikeda and Mikihiro Nomura

Membranes 2020, 10(2), 27; https://doi.org/10.3390/membranes10020027 - 8 Feb 2020

Cited by 5 | Viewed by 3696

Abstract

The development of inorganic membranes has mainly found applicability in liquid separation technologies. However, only a few reports cite the permeation and separation of liquids through inorganic nanofiltration membranes compared with the more popular microfiltration membranes. Herein, we prepared silica membranes using 3,3,3-trifluoropropyltrimethoxysilane [...] Read more.

The development of inorganic membranes has mainly found applicability in liquid separation technologies. However, only a few reports cite the permeation and separation of liquids through inorganic nanofiltration membranes compared with the more popular microfiltration membranes. Herein, we prepared silica membranes using 3,3,3-trifluoropropyltrimethoxysilane (TFPrTMOS) to investigate its liquid permeance performance using four different ion solutions (i.e., NaCl, Na₂SO₄, MgCl₂, and MgSO₄). The TFPrTMOS-derived membranes were deposited above a temperature of 175 °C, where the deposition behavior of TFPrTMOS was dependent on the organic functional groups decomposition temperature. The highest membrane rejection was from NaCl at 91.0% when deposited at 200 °C. For anions, the SO₄²⁻ rejections were the greatest. It was also possible to separate monovalent and divalent anions, as the negatively charged groups on the membrane surfaces retained pore sizes >1.48 nm. Ions were also easily separated by molecular sieving below a pore size of 0.50 nm. For the TFPrTMOS-derived membrane deposited at 175 °C, glucose showed 67% rejection, which was higher than that achieved through the propyltrimethoxysilane membrane. We infer that charge exclusion might be due to the dissociation of hydroxyl groups resulting from decomposition of organic groups. Pore size and organic functional group decomposition were found to be important for ion permeation. Full article

(This article belongs to the Special Issue Mass Transfer in Membranes)

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11 pages, 3409 KiB

Open AccessArticle

Control of Sequential MTO Reactions through an MFI-Type Zeolite Membrane Contactor

by Shusei Tanizume, Toshihiro Yoshimura, Katsunori Ishii and Mikihiro Nomura

Membranes 2020, 10(2), 26; https://doi.org/10.3390/membranes10020026 - 7 Feb 2020

Cited by 9 | Viewed by 3323

Abstract

A membrane for controlling methanol-to-olefin (MTO) reactions was developed, which featured an MFI-type zeolite membrane (Si/Al = 25) that was synthesized on a porous α-alumina substrate using a secondary growth method. Here, the H₂/SF₆ permeance ratios were between 150 and [...] Read more.

A membrane for controlling methanol-to-olefin (MTO) reactions was developed, which featured an MFI-type zeolite membrane (Si/Al = 25) that was synthesized on a porous α-alumina substrate using a secondary growth method. Here, the H₂/SF₆ permeance ratios were between 150 and 450. The methanol conversion rate was 70% with 38% ethylene selectivity and 28% propylene selectivity as determined using a cross-flow membrane contactor. In order to improve the olefin selectivity of the membrane, the MFI zeolite layer (Si/Al = ∞) was coated on an MFI-type zeolite membrane (Si/Al = 25). Using this two-layered membrane system, the olefin selectivity value increased to 85%; this was 19% higher than the value obtained during the single-layer membrane system. Full article

(This article belongs to the Special Issue Mass Transfer in Membranes)

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12 pages, 1673 KiB

Open AccessArticle

Polymer of Intrinsic Microporosity (PIM-1) Membranes Treated with Supercritical CO₂

by Colin A. Scholes and Shinji Kanehashi

Membranes 2019, 9(3), 41; https://doi.org/10.3390/membranes9030041 - 18 Mar 2019

Cited by 32 | Viewed by 6631

Abstract

Polymers of intrinsic microporosity (PIMs) are a promising membrane material for gas separation, because of their high free volume and micro-cavity size distribution. This is countered by PIMs-based membranes being highly susceptible to physical aging, which dramatically reduces their permselectivity over extended periods [...] Read more.

Polymers of intrinsic microporosity (PIMs) are a promising membrane material for gas separation, because of their high free volume and micro-cavity size distribution. This is countered by PIMs-based membranes being highly susceptible to physical aging, which dramatically reduces their permselectivity over extended periods of time. Supercritical carbon dioxide is known to plasticize and partially solubilise polymers, altering the underlying membrane morphology, and hence impacting the gas separation properties. This investigation reports on the change in PIM-1 membranes after being exposed to supercritical CO₂ for two- and eight-hour intervals, followed by two depressurization protocols, a rapid depressurization and a slow depressurization. The exposure times enables the impact contact time with supercritical CO₂ has on the membrane morphology to be investigated, as well as the subsequent depressurization event. The density of the post supercritical CO₂ exposed membranes, irrespective of exposure time and depressurization, were greater than the untreated membrane. This indicated that supercritical CO₂ had solubilised the polymer chain, enabling PIM-1 to rearrange and contract the free volume micro-cavities present. As a consequence, the permeabilities of He, CH₄, O₂ and CO₂ were all reduced for the supercritical CO₂-treated membranes compared to the original membrane, while N₂ permeability remained unchanged. Importantly, the physical aging properties of the supercritical CO₂-treated membranes altered, with only minor reductions in N₂, CH₄ and O₂ permeabilities observed over extended periods of time. In contrast, He and CO₂ permeabilities experienced similar physical aging in the supercritical treated membranes to that of the original membrane. This was interpreted as the supercritical CO₂ treatment enabling micro-cavity contraction to favour the smaller CO₂ molecule, due to size exclusion of the larger N₂, CH₄ and O₂ molecules. Therefore, physical aging of the treated membranes only had minor impact on N₂, CH₄ and O₂ permeability; while the smaller He and CO₂ gases experience greater permeability loss. This result implies that supercritical CO₂ exposure has potential to limit physical aging performance loss in PIM-1 based membranes for O₂/N₂ separation. Full article

(This article belongs to the Special Issue Mass Transfer in Membranes)

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11 pages, 3285 KiB

Open AccessArticle

Preparation of Layer-by-Layer Nanofiltration Membranes by Dynamic Deposition and Crosslinking

by Yan Liu, George Q. Chen, Xiuli Yang and Huining Deng

Membranes 2019, 9(2), 20; https://doi.org/10.3390/membranes9020020 - 24 Jan 2019

Cited by 24 | Viewed by 6291

Abstract

In recent decades, the advancements in layer-by-layer (LBL) assembly technology have provoked increasing interest in the preparation of multilayer polyelectrolyte membranes with excellent performance. In the current study, a novel nanofiltration (NF) membrane was prepared by pressure-driven layer-by-layer (LBL) assembly of polyethylenimine (PEI) [...] Read more.

In recent decades, the advancements in layer-by-layer (LBL) assembly technology have provoked increasing interest in the preparation of multilayer polyelectrolyte membranes with excellent performance. In the current study, a novel nanofiltration (NF) membrane was prepared by pressure-driven layer-by-layer (LBL) assembly of polyethylenimine (PEI) and polyacrylicacid (PAA) on a porous substrate with chemical crosslinking. The effect of deposition pressure on separation performance of the prepared membranes was studied. The surface morphology, hydrophilicity and the charge property of the dynamically-deposited membranes were compared with those prepared by static adsorption. The characterization results showed that dynamic deposition process resulted in a smoother membrane surface with improved hydrophilicity. The mechanism of water-path formation was proposed to interpret the effect of pressure on the membrane performance. Glutaraldehyde (GA) was used as a crosslinker to reduce the number of polyelectrolyte bilayers for obtaining good separation performance. The rejections of different inorganic salts of the dynamically-deposited NF membrane were also investigated. Full article

(This article belongs to the Special Issue Mass Transfer in Membranes)

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22 pages, 7191 KiB

Open AccessArticle

Performance of Void-Free Electrospun SPEEK/Cloisite as a Function of Degree of Dispersion State on Nanocomposite Proton Exchange Membrane for Direct Methanol Fuel Cell Application

by Nuha Awang, Juhana Jaafar, Ahmad Fauzi Ismail, Mohd Hafiz Dzarfan Othman and Mukhlis A. Rahman

Membranes 2019, 9(1), 7; https://doi.org/10.3390/membranes9010007 - 2 Jan 2019

Cited by 12 | Viewed by 3980

Abstract

One of the main problems in direct methanol fuel cell (DMFC) application is methanol crossover. In order to solve the problem, an exfoliated void-free electrospun Sulfonated Poly(Ether Ether Ketone) (SPEEK)/cloisite nanocomposite membrane was developed. The membrane was prepared by immersing electrospun SPEEK/cloisite fiber [...] Read more.

One of the main problems in direct methanol fuel cell (DMFC) application is methanol crossover. In order to solve the problem, an exfoliated void-free electrospun Sulfonated Poly(Ether Ether Ketone) (SPEEK)/cloisite nanocomposite membrane was developed. The membrane was prepared by immersing electrospun SPEEK/cloisite fiber mats onto incomplete solidified SPEEK polymer matrix. A well dispersed and reduction size of cloisite particles that ranges from 0.29–0.39 µm was observed by using Scanning Electron Microscopy Analysis (SEM) and Atomic Force Microscope (AFM). The effect of the morphology of the composite membrane in terms of degree of dispersion state of the Cloisite on the membrane performance was discussed. SP/e-spunCL15 with fully exfoliated structure exhibited the highest performance as compared to other tested membranes and Nafion^® 115 with current density of 1042.2 mAcm⁻² and power density of 1.18 mWcm⁻². Improved morphological, dimensional change properties, and performance assigned to well-dispersed cloisite15A induced by the electrospinning technique make the membranes more efficient for direct methanol fuel cell applications. Full article

(This article belongs to the Special Issue Mass Transfer in Membranes)

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16 pages, 3292 KiB

Open AccessArticle

Preparation of PVA-Based Hollow Fiber Ion-Exchange Membranes and Their Performance for Donnan Dialysis

by Mitsuru Higa, Yuriko Kakihana, Takehiro Sugimoto and Kakuya Toyota

Membranes 2019, 9(1), 4; https://doi.org/10.3390/membranes9010004 - 2 Jan 2019

Cited by 7 | Viewed by 5562

Abstract

Hollow fiber type cation-exchange (C-HF) membranes and hollow fiber type anion-exchange (A-HF) membranes were prepared from poly (vinyl alcohol) (PVA)-based copolymer with cation-exchange groups and by blending PVA and polycation, respectively, by a gel fiber spinning method. In order to control the water [...] Read more.

Hollow fiber type cation-exchange (C-HF) membranes and hollow fiber type anion-exchange (A-HF) membranes were prepared from poly (vinyl alcohol) (PVA)-based copolymer with cation-exchange groups and by blending PVA and polycation, respectively, by a gel fiber spinning method. In order to control the water content of the hollow fiber membranes, the membranes were cross-linked physically by annealing, and then cross-linked chemically by using glutaraldehyde (GA) solutions at various GA concentrations. The outer diameter of C-HF and A-HF membranes were ca. 1000 μm and ca. 1500 μm, respectively, and the thickness of the membranes were ca. 170 μm and 290 μm, respectively. Permeation experiments were carried out in two Donnan dialysis systems, which included mixed 0.1 M NaCl and 0.1 M CaCl₂/C-HF /3 × 10⁻⁴ M CaCl₂ and mixed 0.1 M NaCl and 0.1 M NaNO₃/A-HF/3 × 10⁻⁴ M NaNO₃ to examine ionic perm selectivity of the membranes. In the Donnan dialysis experiments using C-HF membranes, uphill transport of the divalent cations occurred, and, in the case of A-HF membranes, uphill transport of NO₃⁻ ions occurred. C-HF and A-HF membranes had about half of the flux in the uphill transported ions and also about half of the selectivity between the uphill transport ions and driven ions in comparison with those of the commercial flat sheet cation-exchange membrane (Neosepta^® CMX) and anion-exchange membrane (Neosepta^® AMX). Yet, IEC of C-HF and A-HF membranes were about one fifth of CMX and less than half of AMX, respectively. Since hollow fiber membrane module will have higher packing density than a flat membrane stack, the hollow fiber type ion-exchange membranes (IEMs) prepared in this study will have a potential application to a Donnan dialysis process. Full article

(This article belongs to the Special Issue Mass Transfer in Membranes)

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13 pages, 1791 KiB

Open AccessArticle

Alkali Attack on Anion Exchange Membranes with PVC Backing and Binder: II Prediction of Electrical and Mechanical Performances from Simple Optical Analyses

by Shoichi Doi, Maki Kinoshita, Masahiro Yasukawa and Mitsuru Higa

Membranes 2018, 8(4), 133; https://doi.org/10.3390/membranes8040133 - 14 Dec 2018

Cited by 12 | Viewed by 3788

Abstract

Performance of anion exchange membranes (AEMs), including polyvinyl chloride (PVC) as backing and binder, decreases during a repetitive cleaning-in-place (CIP) treatment using alkali. In this study, we have systematically performed two optical analyses, relative total visible (VIS) reflectance and handheld X-ray fluorescence (XRF), [...] Read more.

Performance of anion exchange membranes (AEMs), including polyvinyl chloride (PVC) as backing and binder, decreases during a repetitive cleaning-in-place (CIP) treatment using alkali. In this study, we have systematically performed two optical analyses, relative total visible (VIS) reflectance and handheld X-ray fluorescence (XRF), for alkali-attacked commercially available AEM (Neosepta^® AMX, Tokyo, Japan) with different NaOH immersion conditions (0–1.0 M NaOH at 40–80 °C for 0–168 h). The VIS reflectance and XRF data were then compared with the electrical and mechanical performances (i.e., membrane resistance, proton rejection, amount of fixed-charge sites, and Young’s modulus) of the alkali-attacked AMXs. The result indicated that there are clear linear relationships between their performances and both VIS reflectance and XRF data especially at 40 °C, indicating both optical analyses have a good possibility as a quick diagnosis-in-place (DIP) to predict the resulting performance of the alkali-attacked AMXs. In addition, we also found a clear linear relationship between VIS reflectance and XRF data, so that polyene formations through dehydrochlorination of PVC during alkali attack is one of dominant mechanisms for the performance reduction of the alkali-attacked AMX at 40 °C. These results are promising to be useful for the analysis of ion exchange membranes (IEMs) used in real commercial processes on-site in future. Full article

(This article belongs to the Special Issue Mass Transfer in Membranes)

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13 pages, 1945 KiB

Open AccessArticle

Thickness Effect on CO₂/N₂ Separation in Double Layer Pebax-1657^®/PDMS Membranes

by Roman Selyanchyn, Miho Ariyoshi and Shigenori Fujikawa

Membranes 2018, 8(4), 121; https://doi.org/10.3390/membranes8040121 - 2 Dec 2018

Cited by 56 | Viewed by 10822

Abstract

The effect of thickness in multilayer thin-film composite membranes on gas permeation has received little attention to date, and the gas permeances of the organic polymer membranes are believed to increase by membrane thinning. Moreover, the performance of defect-free layers with known gas [...] Read more.

The effect of thickness in multilayer thin-film composite membranes on gas permeation has received little attention to date, and the gas permeances of the organic polymer membranes are believed to increase by membrane thinning. Moreover, the performance of defect-free layers with known gas permeability can be effectively described using the classical resistance in series models to predict both permeance and selectivity of the composite membrane. In this work, we have investigated the Pebax^®-MH1657/PDMS double layer membrane as a selective/gutter layer combination that has the potential to achieve sufficient CO₂/N₂ selectivity and permeance for efficient CO₂ and N₂ separation. CO₂ and N₂ transport through membranes with different thicknesses of two layers has been investigated both experimentally and with the utilization of resistance in series models. Model prediction for permeance/selectivity corresponded perfectly with experimental data for the thicker membranes. Surprisingly, a significant decrease from model predictions was observed when the thickness of the polydimethylsiloxane (PDMS) (gutter layer) became relatively small (below 2 µm thickness). Material properties changed at low thicknesses—surface treatments and influence of porous support are discussed as possible reasons for observed deviations. Full article

(This article belongs to the Special Issue Mass Transfer in Membranes)

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16 pages, 2537 KiB

Open AccessArticle

Implementation of Spiegler–Kedem and Steric Hindrance Pore Models for Analyzing Nanofiltration Membrane Performance for Smart Water Production

by Remya R. Nair, Evgenia Protasova, Skule Strand and Torleiv Bilstad

Membranes 2018, 8(3), 78; https://doi.org/10.3390/membranes8030078 - 6 Sep 2018

Cited by 26 | Viewed by 7794

Abstract

A predictive model correlating the parameters in the mass transfer-based model Spiegler–Kedem to the pure water permeability is presented in this research, which helps to select porous polyamide membranes for enhanced oil recovery (EOR) applications. Using the experimentally obtained values of flux and [...] Read more.

A predictive model correlating the parameters in the mass transfer-based model Spiegler–Kedem to the pure water permeability is presented in this research, which helps to select porous polyamide membranes for enhanced oil recovery (EOR) applications. Using the experimentally obtained values of flux and rejection, the reflection coefficient σ and solute permeability P_s have been estimated as the mass transfer-based model parameters for individual ions in seawater. The reflection coefficient and solute permeability determined were correlated with the pure water permeability of a membrane, which is related to the structural parameters of a membrane. The novelty of this research is the development of a model that consolidates the various complex mechanisms in the mass transfer of ions through the membrane to an empirical correlation for a given feed concentration and membrane type. These correlations were later used to predict ion rejections of any polyamide membrane with a known pure water permeability and flux with seawater as a feed that aids in the selection of suitable nanofiltration (NF) for smart water production. Full article

(This article belongs to the Special Issue Mass Transfer in Membranes)

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15 pages, 3596 KiB

Open AccessArticle

Effect of DS Concentration on the PRO Performance Using a 5-Inch Scale Cellulose Triacetate-Based Hollow Fiber Membrane Module

by Masahiro Yasukawa, Daisuke Shigefuji, Masafumi Shibuya, Yuki Ikebe, Ryuto Horie and Mitsuru Higa

Membranes 2018, 8(2), 22; https://doi.org/10.3390/membranes8020022 - 1 May 2018

Cited by 8 | Viewed by 5111

Abstract

In this study, pressure-retarded osmosis (PRO) performance of a 5-inch scale cellulose triacetate (CTA)-based hollow fiber (HF) membrane module was evaluated under a wide range of operating conditions (0.0–6.0 MPa of applied pressure, 0.5–2.0 L/min feed solution (FS) inlet flow rate, 1.0–6.0 L/min [...] Read more.

In this study, pressure-retarded osmosis (PRO) performance of a 5-inch scale cellulose triacetate (CTA)-based hollow fiber (HF) membrane module was evaluated under a wide range of operating conditions (0.0–6.0 MPa of applied pressure, 0.5–2.0 L/min feed solution (FS) inlet flow rate, 1.0–6.0 L/min DS inlet flow rate and 0.1–0.9 M draw solution (DS) concentration) by using a PRO/reverse osmosis (RO) hybrid system. The subsequent RO system for DS regeneration enabled the evaluation of the steady-stated module performance. In the case of pilot-scale module operation, since the DS dilution and the feed solution (FS) up-concentration had occurred and was not negligible, unlike the lab-scale experiment, PRO performance strongly depended on operating conditions such as inlet flow rates of both the DS and FS concentration. To compare the module performance with different configurations, we proposed a converted parameter in which a difference of the packing density between the spiral wound (SW) and the HF module was fairly considered. In the case of HF configuration, because of high packing density, volumetric-based performance was higher than that of SW module, that is, the required number of the module would be less than that of SW module in a full-scale PRO plant. Full article

(This article belongs to the Special Issue Mass Transfer in Membranes)

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Review

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21 pages, 4884 KiB

Open AccessEditor’s ChoiceReview

Performance of Polymer Electrolyte Membrane for Direct Methanol Fuel Cell Application: Perspective on Morphological Structure

by Hazlina Junoh, Juhana Jaafar, Nik Abdul Hadi Md Nordin, Ahmad Fauzi Ismail, Mohd Hafiz Dzarfan Othman, Mukhlis A. Rahman, Farhana Aziz and Norhaniza Yusof

Membranes 2020, 10(3), 34; https://doi.org/10.3390/membranes10030034 - 25 Feb 2020

Cited by 47 | Viewed by 9123

Abstract

Membrane morphology plays a great role in determining the performance of polymer electrolyte membranes (PEMs), especially for direct methanol fuel cell (DMFC) applications. Membrane morphology can be divided into two types, which are dense and porous structures. Membrane fabrication methods have different configurations, [...] Read more.

Membrane morphology plays a great role in determining the performance of polymer electrolyte membranes (PEMs), especially for direct methanol fuel cell (DMFC) applications. Membrane morphology can be divided into two types, which are dense and porous structures. Membrane fabrication methods have different configurations, including dense, thin and thick, layered, sandwiched and pore-filling membranes. All these types of membranes possess the same densely packed structural morphology, which limits the transportation of protons, even at a low methanol crossover. This paper summarizes our work on the development of PEMs with various structures and architecture that can affect the membrane’s performance, in terms of microstructures and morphologies, for potential applications in DMFCs. An understanding of the transport behavior of protons and methanol within the pores’ limits could give some perspective in the delivery of new porous electrolyte membranes for DMFC applications. Full article

(This article belongs to the Special Issue Mass Transfer in Membranes)

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