• Membrane Journal
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• v.30 no.2
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• pp.79-96
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• 2020

Secondary energy conversion systems have been briskly developed owing to environmental issue and problems of fossil fuel. They are basically operated based on electro-chemical systems. In addition, ion exchange membranes are one of the significant factors to determine performance in their systems. Therefore, the ion exchange membranes in suitable conditions must be developed to improve the performance for the electro-chemical systems. These ion exchange membranes can be classified into various types such as cation exchange membrane, anion exchange membrane and bipolar membrane. Their membranes have distinct characteristics according to the chemical, physical and morphological structure. In this review, the types of ion exchange membranes and their fabrication processes are described with main characteristics. Moreover, applications of ion exchange membranes in newly developed energy conversion systems such as reverse electrodialysis, redox flow battery and water electrolysis process are described including their roles and requirements.

• Polymer(Korea)
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• v.31 no.3
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• pp.247-254
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• 2007

Heterogeneous anion exchange membranes were prepared by compression molding for the recovery of sulfate ion from waste water. The swelling ratio, transport number, and ion exchange capacity of the heterogeneous anion exchange membranes were increased and their electrical resistances were decreased as the amount of ion exchange resin content in the matrix was raised. The tensile strength of the heterogeneous anion exchange membrane was decreased with increasing the amount of ion exchange resin in the LLDPE. The tensile strength for the LDPE heterogeneous membrane containing 30 wt% anion exchange resin showed the highest value. The water content increased with increasing amount of ion exchange resin in the membrane. Moreover the highest transport number of the membrane was 0.86. The electrical resistance of LDPE matrix membrane with 50 wt% resin showed $46.5{\Omega}{\cdot}cm^2$. Current efficiency of electrodialysis for sulfate ion showed the highest value at the current density of $125 mA/cm^2$ in 0.5 mol/L sulfuric acids solution.

• Membrane Journal
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• v.32 no.5
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• pp.283-291
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• 2022

Hydrogen energy has received much attention as a solution to the supply of renewable energy and to respond to climate change. Hydrogen is the most suitable candidate of storing unused electric power in a large-capacity long cycle. Among the technologies for producing hydrogen, water electrolysis is known as an eco-friendly hydrogen production technology that produces hydrogen without carbon dioxide generation by water splitting reaction. Membranes in water electrolysis system physically separate the anode and the cathode, but also prevent mixing of generated hydrogen and oxygen gases and facilitate ion transfer to complete circuit. In particular, the key to next-generation anion exchange membrane that can compensate for the shortcomings of conventional water electrolysis technologies is to develop high performance anion exchange membrane. Many studies are conducted to have high ion conductivity and excellent durability in an alkaline environment simultaneously, and various materials are being searched. In this review, we will discuss the research trends and points to move forward by looking at the research on anion exchange membranes based on commercial polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) block copolymers.

• Membrane Journal
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• v.26 no.1
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• pp.43-54
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• 2016

In this study, we have prepared engineering polymer-based ionomers and pore-filled ion-exchange membranes (PFIEMs) employing a porous polyethylene substrate and combined them to fabricate the ionomer-PFIEM composite membranes for the reverse electrodialysis (RED) application. Both the electrochemical properties comparable to those of the commercial ion-exchange membranes (AMX/CMX, Astom Corp., Japan) and the physical stability adaptable to the practical uses have been achieved by integrating the ionomers having a high ion conductivity and the PFIEMs with an excellent mechanical strength. The RED performances have been evaluated by employing the prepared ionomer-PFIEM composite membranes and therefore excellent power generation performances were shown as the levels of 86.4% and 104.8% for the anion-exchange membrane and cation-exchange membrane, respectively, compared with those of the commercial membranes.

• Journal of Electrochemical Science and Technology
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• v.8 no.3
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• pp.183-196
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• 2017

The research efforts directed at advancing water electrolysis technology continue to intensify together with the increasing interest in hydrogen as an alternative source of energy to fossil fuels. Among the various water electrolysis systems reported to date, systems employing a solid polymer electrolyte membrane are known to display both improved safety and efficiency as a result of enhanced separation of products: hydrogen and oxygen. Conducting water electrolysis in an alkaline medium lowers the system cost by allowing non-platinum group metals to be used as catalysts for the complex multi-electron transfer reactions involved in water electrolysis, namely the hydrogen and oxygen evolution reactions (HER and OER, respectively). We briefly review the anion exchange membranes (AEMs) and electrocatalysts developed and applied thus far in alkaline AEM water electrolysis (AEMWE) devices. Testing the developed components in AEMWE cells is a key step in maximizing the device performance since cell performance depends strongly on the structure of the electrodes containing the HER and OER catalysts and the polymer membrane under specific cell operating conditions. In this review, we discuss the properties of reported AEMs that have been used to fabricate membrane-electrode assemblies for AEMWE cells, including membranes based on polysulfone, poly(2,6-dimethyl-p-phylene) oxide, polybenzimidazole, and inorganic composite materials. The activities and stabilities of tertiary metal oxides, metal carbon composites, and ultra-low Pt-loading electrodes toward OER and HER in AEMWE cells are also described.

• Korean Chemical Engineering Research
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• v.51 no.5
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• pp.615-621
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• 2013

Membrane characterization methods for aqueous redox flow batteries aqueous RFBs were modified for non-aqueous RFBs. The modified characterization methods, such as ion exchange capacity, transport number, permeability and single cell test, were carried out to evaluate commercial membranes in non-aqueous electrolyte. It was found that columbic efficiency and energy efficiency in a single cell test were dependent on the ion selectivity of commercial anion exchange membranes. Neosepta AHA anion exchange membrane showed the anion transport number of 0.81, which is a relatively low ion selectivity in non-aqueous electrolyte, however, exhibited 92% of coulombic efficiency and 86% of energy efficiency in a single cell test. It was also found that a porous membrane without ion selectivity is suitable for a non-aqueous redox flow battery at a high current density.

• 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.14 no.1
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• pp.26-36
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• 2004

Ultrafiltration membranes based on anion charged poly(bis[4-(3-aminophenoxy)phenyl]sulfone pyromellite) imide derivatives (ACPI) were prepared by the phase inversion method. The polymers have good solubility in aprotic polar solvents. The composition of casting solution and the casting conditions played an important role in determining the permeation characteristics of membrane because the membrane structure could be controlled by the preparation conditions. The extent of fouling-repression was observed by the relative ratio of permeate flux ($J_t$)/pure water flux ($J_0$) and the membrane filtration index (MFI). The characteristics were measured by aqueous solution of bovine serum albumin (BSA) over a pH range of 2.5-9.0. The ACPI membrane having a hydrophilic property was less fouled than the membrane prepared from the original polyimide. With increasing the ion exchange capacity of ACPI membrane, th $\varepsilon$ relative ratio of flux was higher while the membrane filtration index was lower as compared with the original polyimide membrane. From the further away from isoelectric point of bovin serum albumin, the permeation was higher as well as the formation of fouling was more diminish. ACPI membranes having various their properties could be obtained. Further, it was proved that their permeation properties could be determined from the preparation conditions, various operating conditions, and dim $\varepsilon$ rent ion exchange capacity of anion charged polyimide derivatives.

• Membrane Journal
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• v.27 no.5
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• pp.441-448
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• 2017

In this study, the effects of membrane characteristics on the power generation performance in reverse electrodialysis (RED) have been investigated with pore-filled ion-exchange membranes (PFIEMs) prepared by employing a porous polyethylene substrate and the mixtures of three cross-linking agents. As a result, it was confirmed through the correlation analyses that the cross-linking degree and free volume of the PFIEMs were effectively controlled by mixing the cross-linking agents having different molecular sizes, influencing complexly the electrochemical characteristics of the membranes and the power generation performance in RED. In particular, the pore-filled cation-exchange membranes at the optimum cross-linking conditions exhibited the power generation performance superior to that of the commercial membranes and the pore-filled anion-exchange membranes also showed the excellent performance close to that of the commercial membrane.

• Membrane Journal
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• v.32 no.5
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• pp.348-356
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• 2022

With the development of the bio industry, membrane chromatography with a high adsorption efficiency is emerging to replace the existing column chromatography used in the downstream processes of pharmaceuticals, food, etc. In this study, through the deacetylation reaction of two commercial cellulose acetate (CA) membranes with different pore sizes, the porous regenerated cellulose (RC) supports for membrane chromatography were obtained to attach the anion exchange ligands. The adsorptive membranes for anion exchange were prepared by attaching an anion exchange ligand ([3-(methacryloylamino) propyl] trimethylammonium chloride) containing quaternary ammonium groups on the RC supports by grafting and UV polymerization. The protein adsorption capacities of the prepared membranes were obtained through both the static binding capacity (SBC) and the dynamic adsorption capacity (DBC) measurement. As a result, the membrane chromatography with the smaller the pore size, the larger the surface area showed the highest protein adsorption capacity. Membrane chromatography which was prepared by using deacetylated commercial CA support with MAPTAC ligand (i.e., RC 0.8 + MAPTAC: 43.69 mg/ml, RC 3.0 + MAPTAC: 36.33 mg/ml) showed a higher adsorption capacity compared to commercial membrane chromatography (28.38 mg/ml).