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Membranes
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Novel Ion-Exchange Membranes
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Novel Ion-Exchange Membranes

A special issue of Membranes (ISSN 2077-0375). This special issue belongs to the section "Membrane Chemistry".

Deadline for manuscript submissions: closed (31 May 2021) | Viewed by 18435

Special Issue Editors

Prof. Dr. Akihiko Tanioka

E-Mail Website
Guest Editor
Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan
Interests: nanofiber; membrane with nanostructure; ion-exchange materials for energy exchange; surface chemistry
Prof. Dr. Hidetoshi Matsumoto

E-Mail Website
Guest Editor
Professor, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, S8-27, Japan
Interests: functional design of nanomaterials, nanofibers, membranes, and thin films; applications of functional materials in energy and environmental fields

Special Issue Information

Dear Colleagues,

Ion-exchange membranes were developed more than 50 years ago and have been applied to caustic soda manufacturing, energy production by fuel cell, salt production from the sea, pure water production from brackish water, nitrate nitrogen removal from groundwater, heavy metal ion removal from contaminated water, etc. Recently, they have begun to attract attention again as materials necessary for solving global environmental problems because they are capable of energy production and storage, as well as being useful for the removal of harmful pollutants. Furthermore, recent advances in nanotechnology are expected to lead to the emergence of new ion exchange materials, and are showing new developments in the progress of ion exchange membranes. We expect contributions from various fields for novel ion-exchange membranes.

Prof. Dr. Akihiko Tanioka
Prof. Dr. Hidetoshi Matsumoto
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Membranes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Ion-exchange
  • Energy production
  • Energy storage
  • Environmental problems
  • Pollutant removal
  • Nanotechnology

Published Papers (6 papers)

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Research

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13 pages, 1535 KiB  
Article
A Solid-State Pathway towards the Tunable Carboxylation of Cellulosic Fabrics: Controlling the Surface’s Acidity
by Eugenio H. Otal, Manuela L. Kim, Juan P. Hinestroza and Mutsumi Kimura
Membranes 2021, 11(7), 514; https://doi.org/10.3390/membranes11070514 - 08 Jul 2021
Cited by 1 | Viewed by 2427
Abstract
We report on a tunable solid-state approach to modify the acidity of cotton substrates using citric, oxalic, and fumaric acids. The first stage of the method involves soaking the cotton swatches in an ethanolic saturated solution of the corresponding acid. After drying, the [...] Read more.
We report on a tunable solid-state approach to modify the acidity of cotton substrates using citric, oxalic, and fumaric acids. The first stage of the method involves soaking the cotton swatches in an ethanolic saturated solution of the corresponding acid. After drying, the carboxylation reaction proceeds at high temperature (T > 100 °C) and in solid state. We quantified the effect of temperature and reaction time on the solid-state carboxylation reaction, which allowed us to tune the carboxylation degree and the acidity of the surface. We characterized the modified cotton by performing adsorption isotherms and by determining the kinetics of adsorption of a cationic dye: methylene blue (MB). We found that the MB uptake kinetics varied as a function of the acidic strength of the surface, which is closely related to the strength of the acid used for surface modification. The proposed solid-state cotton carboxylation procedure allows us to achieve sustainable cotton modification, which constitutes a starting point for several applications using cotton as the substrate. Full article
(This article belongs to the Special Issue Novel Ion-Exchange Membranes)
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8 pages, 11256 KiB  
Communication
Microstructure Investigation of Polymer Electrolyte Fuel Cell Catalyst Layers Containing Perfluorosulfonated Ionomer
by Maito Koga, Hidetoshi Matsumoto, Mitsunori Kunishima, Masatoshi Tokita, Hiroyasu Masunaga, Noboru Ohta, Akihisa Takeuchi, Junji Mizukado, Hidekazu Sugimori, Kazuhiko Shinohara, Suguru Uemura, Toshihiko Yoshida and Shuichiro Hirai
Membranes 2021, 11(7), 466; https://doi.org/10.3390/membranes11070466 - 24 Jun 2021
Cited by 2 | Viewed by 2973
Abstract
Perfluorosulfonated ionomers are the most successful ion-exchange membranes at an industrial scale. One recent, cutting-edge application of perfluorosulfonated ionomers is in polymer electrolyte fuel cells (PEFCs). In PEFCs, the ionomers are used as a component of the catalyst layer (CL) in addition to [...] Read more.
Perfluorosulfonated ionomers are the most successful ion-exchange membranes at an industrial scale. One recent, cutting-edge application of perfluorosulfonated ionomers is in polymer electrolyte fuel cells (PEFCs). In PEFCs, the ionomers are used as a component of the catalyst layer (CL) in addition to functioning as a proton-exchange membrane. In this study, the microstructures in the CLs of PEFCs were characterized by combined synchrotron X-ray scattering and transmission electron microscopy (TEM) analyses. The CL comprised a catalyst, a support, and an ionomer. Fractal dimensional analysis of the combined ultrasmall- and small-angle X-ray scattering profiles indicated that the carbon-black-supported Pt catalyst (Pt/CB) surface was covered with the ionomer in the CL. Anomalous X-ray scattering revealed that the Pt catalyst nanoparticles on the carbon surfaces were aggregated in the CLs. These findings are consistent with the ionomer/catalyst microstructures and ionomer coverage on the Pt/CB surface obtained from TEM observations. Full article
(This article belongs to the Special Issue Novel Ion-Exchange Membranes)
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13 pages, 2675 KiB  
Article
Ionic Transport Properties of Cation-Exchange Membranes Prepared from Poly(vinyl alcohol-b-sodium Styrene Sulfonate)
by Yuriko Kakihana, N. Awanis Hashim, Taiko Mizuno, Marika Anno and Mitsuru Higa
Membranes 2021, 11(6), 452; https://doi.org/10.3390/membranes11060452 - 19 Jun 2021
Cited by 3 | Viewed by 2441
Abstract
Membrane resistance and permselectivity for counter-ions have important roles in determining the performance of cation-exchange membranes (CEMs). In this study, PVA-based polyanions—poly(vinyl alcohol-b-sodium styrene sulfonate)—were synthesized, changing the molar percentages CCEG of the cation-exchange groups with respect to the vinyl [...] Read more.
Membrane resistance and permselectivity for counter-ions have important roles in determining the performance of cation-exchange membranes (CEMs). In this study, PVA-based polyanions—poly(vinyl alcohol-b-sodium styrene sulfonate)—were synthesized, changing the molar percentages CCEG of the cation-exchange groups with respect to the vinyl alcohol groups. From the block copolymer, poly(vinyl alcohol) (PVA)-based CEMs, hereafter called “B-CEMs”, were prepared by crosslinking the PVA chains with glutaraldehyde (GA) solution at various GA concentrations CGA. The ionic transport properties of the B-CEMs were compared with those previously reported for the CEMs prepared using a random copolymer—poly(vinyl alcohol-co-2-acrylamido-2-methylpropane sulfonic acid)—hereafter called ”R-CEMs”. The B-CEMs had lower water content than the R-CEMs at equal molar percentages of the cation-exchange groups. The charge density of the B-CEMs increased as CCEG increased, and reached a maximum value, which increased with increasing CGA. A maximum charge density of 1.47 mol/dm3 was obtained for a B-CEM with CCEG = 2.9 mol% and CGA = 0.10 vol.%, indicating that the B-CEM had almost two-thirds of the permselectivity of a commercial CEM (CMX: ASTOM Corp. Japan). The dynamic transport number and membrane resistance of a B-CEM with CCEG = 8.3 mol% and CGA = 0.10 vol.% were 0.99 and 1.6 Ωcm2, respectively. The B-CEM showed higher dynamic transport numbers than those of the R-CEMs with similar membrane resistances. Full article
(This article belongs to the Special Issue Novel Ion-Exchange Membranes)
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14 pages, 4703 KiB  
Article
Transparent Ion-Exchange Membrane Exhibiting Intense Emission under a Specific pH Condition Based on Polypyridyl Ruthenium(II) Complex with Two Imidazophenanthroline Groups
by Hajime Kamebuchi, Satoshi Tamaki, Atsushi Okazawa and Norimichi Kojima
Membranes 2021, 11(6), 400; https://doi.org/10.3390/membranes11060400 - 27 May 2021
Viewed by 2340
Abstract
The development and the photophysical behavior of a transparent ion-exchange membrane based on a pH-sensitive polypyridyl ruthenium(II) complex, [(bpy)2RuII(H2bpib)RuII(bpy)2](ClO4)4 (bpy = 2,2′-bipyridine, H2bpib = 1,4-bis([1,10]phenanthroline[5,6-d]-imidazol-2-yl)benzene), are [...] Read more.
The development and the photophysical behavior of a transparent ion-exchange membrane based on a pH-sensitive polypyridyl ruthenium(II) complex, [(bpy)2RuII(H2bpib)RuII(bpy)2](ClO4)4 (bpy = 2,2′-bipyridine, H2bpib = 1,4-bis([1,10]phenanthroline[5,6-d]-imidazol-2-yl)benzene), are experimentally and theoretically reported. The emission spectra of [(bpy)2RuII(H2bpib)RuII(bpy)2]@Nafion film were observed between pH 2 and pH 11 and showed the highest relative emission intensity at pH 5 (λmaxem = 594.4 nm). The relative emission intensity of the film significantly decreased down to 75% at pH 2 and 11 compared to that of pH 5. The quantum yields (Φ) and lifetimes (τ) showed similar correlations with respect to pH, Φ = 0.13 and τ = 1237 ns at pH 5, and Φ = 0.087 and τ = 1014 ns and Φ = 0.069 and τ = 954 ns at pH 2 and pH 11, respectively. These photophysical data are overall considerably superior to those of the solution, with the radiative- (kr) and non-radiative rate constants (knr) at pH 5 estimated to be kr = 1.06 × 105 s−1 and knr = 7.03 × 105 s−1. Density functional theory calculations suggested the contribution of ligand-to-ligand- and intraligand charge transfer to the imidazolium moiety in Ru-H3bpib species, implying that the positive charge on the H3bpib ligand works as a quencher. The Ru-Hbpib species seems to enhance non-radiative deactivation by reducing the energy of the upper-lying metal-centered excited state. These would be responsible for the pH-dependent “off-on-off” emission behavior. Full article
(This article belongs to the Special Issue Novel Ion-Exchange Membranes)
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12 pages, 4506 KiB  
Article
Preparation of Perfluorosulfonated Ionomer Nanofibers by Solution Blow Spinning
by Masahiro Shinkawa, Kazunori Motai, Keita Eguchi, Wataru Takarada, Minoru Ashizawa, Hiroyasu Masunaga, Noboru Ohta, Yuhei Hayamizu and Hidetoshi Matsumoto
Membranes 2021, 11(6), 389; https://doi.org/10.3390/membranes11060389 - 25 May 2021
Cited by 8 | Viewed by 3358
Abstract
In this work, we report the preparation of high-purity perfluorosulfonated ionomer (Nafion) nanofibers (NFs) via solution blow spinning (SBS). Fiber formation in solution jet spinning is strongly dependent on the structure of the spinning solution. Upon adding a small amount of poly(ethyleneoxide) (PEO) [...] Read more.
In this work, we report the preparation of high-purity perfluorosulfonated ionomer (Nafion) nanofibers (NFs) via solution blow spinning (SBS). Fiber formation in solution jet spinning is strongly dependent on the structure of the spinning solution. Upon adding a small amount of poly(ethyleneoxide) (PEO) as a spinning aid to Nafion dispersion, most of the highly ordered Nafion aggregate disappeared, allowing the stable production of bead-free and smooth high-purity NFs (Nafion/PEO = 99/1) by SBS. The microstructure of the blowspun Nafion NFs differed from that of electrospun NFs. In the blowspun NFs, incomplete microphase separation between hydrophilic (ionic) and hydrophobic domains was observed, but the crystallization of CF2−CF2 chains was enhanced owing to the high extensional strain rate and rapid solidification during SBS. These findings provide fundamental information for the preparation and characterization of blowspun Nafion NFs. Full article
(This article belongs to the Special Issue Novel Ion-Exchange Membranes)
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Review

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28 pages, 2906 KiB  
Review
De Novo Ion-Exchange Membranes Based on Nanofibers
by Shaoling Zhang, Akihiko Tanioka and Hidetoshi Matsumoto
Membranes 2021, 11(9), 652; https://doi.org/10.3390/membranes11090652 - 25 Aug 2021
Cited by 7 | Viewed by 3849
Abstract
The unique functions of nanofibers (NFs) are based on their nanoscale cross-section, high specific surface area, and high molecular orientation, and/or their confined polymer chains inside the fibers. The introduction of ion-exchange (IEX) groups on the surface and/or inside the NFs provides de [...] Read more.
The unique functions of nanofibers (NFs) are based on their nanoscale cross-section, high specific surface area, and high molecular orientation, and/or their confined polymer chains inside the fibers. The introduction of ion-exchange (IEX) groups on the surface and/or inside the NFs provides de novo ion-exchangers. In particular, the combination of large surface areas and ionizable groups in the IEX-NFs improves their performance through indices such as extremely rapid ion-exchange kinetics and high ion-exchange capacities. In reality, the membranes based on ion-exchange NFs exhibit superior properties such as high catalytic efficiency, high ion-exchange and adsorption capacities, and high ionic conductivities. The present review highlights the fundamental aspects of IEX-NFs (i.e., their unique size-dependent properties), scalable production methods, and the recent advancements in their applications in catalysis, separation/adsorption processes, and fuel cells, as well as the future perspectives and endeavors of NF-based IEMs. Full article
(This article belongs to the Special Issue Novel Ion-Exchange Membranes)
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