• Membrane Journal
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• v.32 no.4
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• pp.209-217
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• 2022

Ion exchange membrane (IEM) is an important class of membrane applied in batteries, fuel cells, chloride-alkali processes, etc to separate various mono and multivalent ions. The membrane process is based on the electrically driven force, green separation method, which is an emerging area in desalination of seawater and water treatment. Electrodialysis (ED) is a technique in which cations and anions move selectively along the IEM. Anion exchange membrane (AEM) is one of the important components of the ED process which is critical to enhancing the process efficiency. The introduction of cross-linking in the IEM improves the ion-selective separation performance due to the reduction of free volume. During the desalination of seawater by reverse osmosis (RO) process, there is a lot of dissolved salt present in the concentrate of RO. So, the ED process consisting of a monovalent cation-selective membrane reduces fouling and improves membrane flux. This review is divided into three sections such as electrodialysis (ED), anion exchange membrane (AEM), and cation exchange membrane (CEM).

• Polymer(Korea)
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• v.39 no.1
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• pp.157-164
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• 2015

In this study, we synthesized poly(vinylimidazole-co-trifluoroethylmethacrylate-co-divinylbenzene) (PVTD) copolymer and introduced functional group through quaternization reaction for removing nitrate from drinking water. Also, optimizing conditions (reaction time, reaction temperature and functionalized agents concentration) for introducing the functional group were confirmed. The basic properties such as water uptake, swelling ratio, electrical resistance, ion exchange capacity and anion permselectivity for removing nitrate from drinking water were measured. The optimal values of water uptake, electrical resistance and ion exchange capacity of synthesized anion exchange membrane were 51.2%, $5.4{\Omega}{\cdot}cm^2$, and 1.04 meq/g, respectively.

• Polymer(Korea)
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• v.36 no.5
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• pp.564-572
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• 2012

A terpolymer of vinylbenzyl chloride-co-ethyl methacrylate-co-styrene (VBC-EMA-St) was prepared for membrane capacitive deionization (MCDI) by radical polymerization and amination reaction of various amination times. Nonfluoro aminated VBC-EMA-St anion-exchange membranes were characterized by Fourier transform infrared (FTIR) spectrometry. Molecular weight, polydispersity and thermal stability were obtained by gel permeation chromatography (GPC) and thermogravimetric analysis (TGA). The basic properties such as water uptake, ion exchange capacity, electrical resistance and CDI charge-discharge current were measured. The optimal values of ion exchange capacity, water uptake, electrical resistance and molecular weight of synthesized anion-exchange membrane were 1.69 meq/g, 23.7%, 1.61 ${\Omega}{\cdot}cm$ and $3.4{\times}10^4$ g/mol, respectively. As compared with conventional membrane, the pattern of cyclic charge-discharge current of synthesized anion-exchange membrane indicated efficient electrosorption and desorption.

• Membrane Journal
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• v.25 no.2
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• pp.152-161
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• 2015

In this study, novel pore-filled anion-exchange membranes (PFAEMs) with low electrical resistance, high permselectivity, and low water-splitting flux property under a concentration polarization condition have been developed for the enhancement in the efficiency of electrochemical water treatment processes. The base membranes have been prepared by filling a copolymer containing quaternary ammonium groups with an excellent ion-exchange capability into a porous polyolefin substrate, showing a high performance superior to that of a commercial membrane. In addition, it was confirmed that the electrochemical membrane performances are preserved while the water-splitting flux is effectively controlled by coating an imidazolium polymer onto the surface of the base membrane. The prepared PFAEMs revealed remarkably low electrical resistances of about 1/6~1/8 compared to those of a commercial membrane, and simultaneously low water-splitting flux comparable with that of cation-exchange membranes under a concentration polarization condition.

• Membrane Journal
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• v.26 no.6
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• pp.432-448
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• 2016

In the last decade, various types of energy harvesting and conversion systems based on ion exchange membranes (IEMs) have been developed for eco-friendly power generation and energy-grid systems. In these membrane-based energy systems, high ion selectivity and conductivity properties of IEMs are critical parameters to improve efficiency of the systems such as proton exchange membrane fuel cells, anion exchange membrane fuel cells, redox flow batteries, water electrodialysis for hydrogen production, and reverse electrodialysis. This article suggests variable approaches to overcome trade-off limitation of polymeric membrane ion transport properties by reviewing various types of composite ion-exchange membranes including novel inorganic-organic nanocomposite membrane, surface modified membranes, cross-linked and pore-filled membranes.

• Membrane Journal
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• v.34 no.1
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• pp.70-78
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• 2024

A photo-crosslinked anion exchange membrane (AEM) based on quaternary-aminated polyacrylates was developed for reverse electrodialysis (RED). Although reverse electrodialysis is a clean and renewable energy generation system, the low power output and high membrane cost are serious obstacles to its commercialization. Cross-linked AEMs without any polymer supporters were fabricated through photo-crosslinking between polymer-typed acrylates with anion conducting groups, in particular, polymer-typed acrylates were synthesized based on engineering plastic with outstanding mechanical and chemical property. The fabricated membranes showed outstanding physical, chemical, and electrochemical properties. The area resistance of the fabricated membranes (CQAPPOA-20, CQAPPOA-35, and CQAPPOA-50) were ~50% lower than that of AMV (2.6 Ω cm²). Moreover, the transport number of CQAPPOA-35 wase comparable to that of AMV, despite the thin thickness (40 ㎛) of the fabricated membranes. The RED stack with the CQAPPOA-35 membrane provided an excellent maximum power density of 2.327 W m^-2 at a flow rate of 100 mL min^-1, which is 15% higher than that (2.026 W m^-2) of the RED stack with the AMV membrane. Considering easy fabrication process by UV photo-crosslinking and outstanding RED stack properties, the CQAPPOA-35 membrane is a promising candidate for REDs.

• Membrane Journal
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• v.25 no.4
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• pp.310-319
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• 2015

Three kinds of anion-exchangeable functional groups with different hydrocarbon molecular structures were introduced to vinyl benzyl chloride-based membrane to understand the effect of attached function in anion-exchange membrane. Trimethylamine (TMA) as an aliphatic fuction, N-methylpiperidine (MP) as an alicyclic fuction and pyridine (Py) as an aromatic function were introduced by amination. The respective reactivity was observed by the trace of membrane resistance( MER)/ion exchange capacity (IEC) and the increasing order of reactivity was Py < MP < TMA. Meanwhile, SEM photograph showed the attached Py ion-exchange membrane was the most homogenous and compact structure in the study. In electrochemical properties, the attached Py ion-exchange membrane showed the MER ($5.0{\Omega}{\cdot}cm^2$ >, in 0.5 mol/L NaCl), comparable to those of commercial membrane (AMX). All results showed that the resonance structure of attached functional group might contribute to the preparation of homogenous anion-exchange membrane.

• Journal of the Korean Electrochemical Society
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• v.25 no.2
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• pp.88-94
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• 2022

The anion exchange membrane used in alkaline membrane fuel cells transports hydroxide ions, and ion conductivity affects fuel cell performance. Thus, the measurement of absolute hydroxide ion conductivity is essential. However, it is challenging to accurately measure hydroxide ion conductivity since hydroxide ions are easily poisoned in the form of bicarbonate by carbon dioxide in the atmosphere. In this study, we applied electrochemical ion exchange treatment to measure the absolute hydroxide ion conductivity of the anion exchange membrane. In addition, we investigated the effect of carbon dioxide poisoning of hydroxide ions on electrochemical performance by measuring bicarbonate conductivity. Commercial anion exchange membranes (FAA-3-50 and Orion TM1) and polyphenylene-based block copolymer (QPP-6F) were used.

• Polymer(Korea)
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• v.32 no.1
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• pp.70-76
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• 2008

The PES-g-BTCA membrane was synthesized by UV irradiation method and then used to be modified into the PES anion exchange membrane by the amination reaction. Their chemical structures and adsorption properties were investigated. The degree of grafting and amination were increased with increasing the reaction time and had the maximum values of 138% and 1.20 mmol/g at 80 min, respectively. The initial thermal degradation temperature of PES membrane was $400^{\circ}C$. Which was reduced as the surface modification reaction had proceeded. The values of contact angle for PES membrane were decreased from 68.1 to $40.2^{\circ}$ with increasing the extent of amination, the water up-take and ion exchange capacity were also increased with increasing UV irradiation time until 80 min. The average pore size and BET surface area were decreased in order of PES, PES-g-BTCA, and aminated PES ion exchange membrane. Their average pore sizes were 624.8, 359.7, and 138.5 ${\AA}$, and their surface areas were 10.1,9.7 and 1.7 $m^2/g$, respectively.

• Membrane Journal
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• v.29 no.3
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• pp.173-182
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• 2019

Much research has been made for finding new and eco-friendly alternative sources of energy to solve the problems related with the pollution caused by emissions of greenhouse gases such as carbon dioxide as the use of fossil fuels increases worldwide. Among them, fuel cells draws particular interests as an eco-friendly energy generator because only water is obtained as a by-product. Anion exchange membrane-based alkaline fuel cell (AEMFC) that uses anion exchange membrane as an electrolyte is of increased interest recently because of its advantages in using low-cost metal catalyst unlike the PEMFC (potton exchange membrane fuel cell) due to the high-catalyst activity in alkaline conditions. The main properties required as an anion exchange membrane are high hydroxide conductivity and chemical stability at high pH. Recently we reported a chemically crosslinked poly(2-dimethyl-1,4-phenylene oxide) (PPO) by reacting PPO with N,N,N',N'-tetramethyl-1,6-hexanediamine as novel anion exchange membranes. In the current work, we further developed the same crosslinked polymer but having enhanced physicochemical properties, including higher conductivity, increased mechanical and dimensional stabilities by using the PPO with a higher molecular weight and also by increasing the crosslinking density. The obtained polymer membrane also showed a good cell performance.