scholarly journals Inorganic Pseudo Ion Exchange Membranes—Concepts and Preliminary Experiments

2018 ◽  
Vol 8 (11) ◽  
pp. 2142 ◽  
Author(s):  
Joost Veerman ◽  
Damnearn Kunteng

Reverse electrodialysis (RED) is a method to produce electricity from the reversible mixing of two salt solutions with different concentrations. RED was first employed for energy generation using sea and river water. New fields of application are energy storage and heat-to-power conversion. In energy storage applications, a stack operates in ED mode during charge and in RED mode during discharge. In a heat-to-power system, the RED stack produces electricity and the outgoing solutions are returned to their original concentrations in a heat-driven regenerator. In both new applications, the salt solutions are circulated and there is a free choice of the combination of salt and membranes for optimal performance. However, classical polymer-based membranes have some disadvantages: they are less suited for operation at higher temperatures, have reduced permselectivity at higher concentrations, and are rather permeable to water, causing an imbalance of the feed waters. We developed a new concept of pseudo-membrane (PM): a metal sheet (sometimes covered with an insoluble salt) on which opposite electrochemical reactions occur at each side of the metal surface. Because a PM is dissolving at one side and growing at the other side during operation, the current should be inverted periodically. We tested a zinc sheet as a pseudo cation exchange membrane for Zn2+ ions and a silver chloride–covered silver plate as a pseudo anion exchange membrane for Cl− ions in three steps. First, a stack was built with Ag/AgCl membranes in combination with normal cation exchange membranes and operated with NaCl solutions. The next stack was based on Zn membranes together with normal anion exchange membranes. This stack was fed with ZnCl2 solutions. Finally, we tested a stack with zinc and Ag/AgCl pseudo-membranes with a ZnCl2 solution. The latter RED system worked; however, after standing for one night, the stack did not function and appeared to be damaged by redox reactions. This failure was the basis for general considerations about the possibilities of ED and RED hybrid stacks, consisting of a combination of classical and pseudo ion exchange membranes. Finally, we consider the possibility of using intercalation electrodes as a pseudo-membrane.

Membranes ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 145 ◽  
Author(s):  
Liliana Villafaña-López ◽  
Daniel M. Reyes-Valadez ◽  
Oscar A. González-Vargas ◽  
Victor A. Suárez-Toriello ◽  
Jesús S. Jaime-Ferrer

Salinity gradient power is a renewable, non-intermittent, and neutral carbon energy source. Reverse electrodialysis is one of the most efficient and mature techniques that can harvest this energy from natural estuaries produced by the mixture of seawater and river water. For this, the development of cheap and suitable ion-exchange membranes is crucial for a harvest profitability energy from salinity gradients. In this work, both anion-exchange membrane and cation-exchange membrane based on poly(epichlorohydrin) and polyvinyl chloride, respectively, were synthesized at a laboratory scale (255 c m 2) by way of a solvent evaporation technique. Anion-exchange membrane was surface modified with poly(ethylenimine) and glutaraldehyde, while cellulose acetate was used for the cation exchange membrane structural modification. Modified cation-exchange membrane showed an increase in surface hydrophilicity, ion transportation and permselectivity. Structural modification on the cation-exchange membrane was evidenced by scanning electron microscopy. For the modified anion exchange membrane, a decrease in swelling degree and an increase in both the ion exchange capacity and the fixed charge density suggests an improved performance over the unmodified membrane. Finally, the results obtained in both modified membranes suggest that an enhanced performance in blue energy generation can be expected from these membranes using the reverse electrodialysis technique.


Membranes ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 4
Author(s):  
Mitsuru Higa ◽  
Yuriko Kakihana ◽  
Takehiro Sugimoto ◽  
Kakuya Toyota

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.


2015 ◽  
Vol 3 (33) ◽  
pp. 16948-16952 ◽  
Author(s):  
Daishuang Zhang ◽  
Xiaoming Yan ◽  
Gaohong He ◽  
Le Zhang ◽  
Xinhong Liu ◽  
...  

We proposed an integrally thin skinned asymmetric anion exchange membrane with sufficiently low ion exchange capacity for vanadium flow batteries (VFBs), and this work provides new insights into the design, fabrication and commercialization of ion exchange membranes for VFBs.


2012 ◽  
Author(s):  
Mahadevan. M. ◽  
Lay Pee Lin ◽  
Zainal Abidin M. Y. ◽  
Mohamad Roji Sarmidi

Elektrodialisis merupakan suatu proses yang menggunakan perbezaan keupayaan elektrik sebagai daya penggerak yang menyebabkan pergerakan ion-ion dalam sesuatu elektronit. Membran yang digunakan dalam proses ini akan membenarkan sama ada cas-cas positif atau negatif sahaja melaluinya bergantung kepada kumpulan berfungsi yang terikat pada membran. Objektif projek penyelidikan ini adalah untuk menghasilkan membran pertukaran kation yang digunakan dalam proses elektrodialisis. Membran-membran pertukaran kation yang dihasilkan terbahagi kepada lima jenis, dan diberi nama sebagai BERL–30, 40, 50, 60, dan 70. Kelima-lima jenis membran ini berbeza dari segi kandungan resin yang berfungsi sebagai vektor pertukaran cas kation. Di samping penyediaan membran, penyelidikan ini juga meliputi aspek pencirian membran tersebut serta perbandingan dengan membran komersial. Kriteria yang dikaji adalah ketebalan membran, sifat kebolehtelapan membran, kapasiti pertukaran ion, kapasiti kepekatan ion kumpulan berfungsi, morfologi struktur membran, ujian kestabilan kimia dan kandungan air membran. Secara keseluruhannya, didapati peratus kandungan resin yang tinggi boleh meningkatkan kapasiti pertukaran ion, peratus kebolehtelapan membran serta kapasiti kepekatan ion kumpulan berfungsi. Antara membran yang dihasilkan, membran pertukaran kation jenis BERL–70 merupakan membran yang berpotensi dalam penggunaan proses elektrodialisis. Kata kunci: Membran pertukaran kation, polisulfona, resin pertukaran ion, ciri-ciri membran, elekrodialisis The objective of this work is to prepare an anion exchange membrane from polysulfone binder–ion exchange resin, which can be used in electrodialysis process. The cation exchange membranes were prepared by the solution casting method. The prepared anion exchange membranes are different from the conventional cation exchange membranes because its functional group is not derived from chlorosulfonic acid but from the absorption of anion exchange resins. The content of resins in each set of the prepared cation exchange membrane varied and were named as BERL–30, 40, 50, 60, and 70. In addition, the performance and behaviour of the prepared anion exchange membrane were evaluated and compared with the commercial cation exchange membranes. The physico-chemical properties of anion exchange membrane were determined by measuring the membrane thickness, permselectivity, and concentration of ion exchange capacity, chemical stability, water content, and scanning electron microscope (SEM). It was found that the increase in the quantity of resin (%) would increase the capacity of ion exchange, percentage of permselectivity, and capacity concentration of ion exchange group. The experimental results showed that cation exchange membrane has the potential to be used in electrodialysis process. Keywords: Cation exchange membrane, electrodialysis, polysulfone, ion exchange resin, membrane characterisation


Membranes ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 217
Author(s):  
AHM Golam Hyder ◽  
Brian A. Morales ◽  
Malynda A. Cappelle ◽  
Stephen J. Percival ◽  
Leo J. Small ◽  
...  

Electrodialysis (ED) desalination performance of different conventional and laboratory-scale ion exchange membranes (IEMs) has been evaluated by many researchers, but most of these studies used their own sets of experimental parameters such as feed solution compositions and concentrations, superficial velocities of the process streams (diluate, concentrate, and electrode rinse), applied electrical voltages, and types of IEMs. Thus, direct comparison of ED desalination performance of different IEMs is virtually impossible. While the use of different conventional IEMs in ED has been reported, the use of bioinspired ion exchange membrane has not been reported yet. The goal of this study was to evaluate the ED desalination performance differences between novel laboratory‑scale bioinspired IEM and conventional IEMs by determining (i) limiting current density, (ii) current density, (iii) current efficiency, (iv) salinity reduction in diluate stream, (v) normalized specific energy consumption, and (vi) water flux by osmosis as a function of (a) initial concentration of NaCl feed solution (diluate and concentrate streams), (b) superficial velocity of feed solution, and (c) applied stack voltage per cell-pair of membranes. A laboratory‑scale single stage batch-recycle electrodialysis experimental apparatus was assembled with five cell‑pairs of IEMs with an active cross-sectional area of 7.84 cm2. In this study, seven combinations of IEMs (commercial and laboratory-made) were compared: (i) Neosepta AMX/CMX, (ii) PCA PCSA/PCSK, (iii) Fujifilm Type 1 AEM/CEM, (iv) SUEZ AR204SZRA/CR67HMR, (v) Ralex AMH-PES/CMH-PES, (vi) Neosepta AMX/Bare Polycarbonate membrane (Polycarb), and (vii) Neosepta AMX/Sandia novel bioinspired cation exchange membrane (SandiaCEM). ED desalination performance with the Sandia novel bioinspired cation exchange membrane (SandiaCEM) was found to be competitive with commercial Neosepta CMX cation exchange membrane.


Membranes ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 228 ◽  
Author(s):  
Shoichi Doi ◽  
Nobuya Takumi ◽  
Yuriko Kakihana ◽  
Mitsuru Higa

Systematic alkali immersion tests of cation-exchange membranes (CEM) with polyvinyl chloride (PVC) as their backing and binder were conducted to compare that of an Anion-exchange membrane (AEM) with the same PVC materials to investigate the mechanism of dehydrochlorination. In the immersion tests, originally colorless and transparent AEM turned violet, and chemical structure analysis showed that polyene was produced by the dehydrochlorination reaction. However, the CEM did not change in color, chemical structure or membrane properties during the test with less than 1M alkali solutions. According to the Donnan equilibrium theory and the experiments using CEM and AEM, the hydroxide ion concentration in the CEM was much lower than that in the AEM under the same conditions. However, when the alkali immersion test was performed using the CEM under more severe conditions (6 M for 168 h at 40 °C), there was a slight change in the color and chemical structure of the CEM, clearly indicating that not only AEMs, but also CEMs with PVC matrixes were deteriorated by alkali, depending on the conditions.


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