• 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.

• Applied Chemistry for Engineering
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• v.8 no.1
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• pp.29-38
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• 1997

In the w/o concentrated emulsion, the volume fraction of the dispersed is greater than 0.74 and the hydrophilic liquid is dispersed in the hydrophobic liquid of the continuous phase. The emulsion has the same appearance and behaviour as a gel. The polarity of the hydrophilic liquids and hydrophobic liquids, the pH and the ionic strength of the hydrophilic liquid are found to be important factors in the stability at the polymerization temperature such as $50^{\circ}C$. The lower the polarity of the hydrophobic liquid and the higher the polarity of the hydrophilic liquid, the more stable the emulsion. Electron microscopy studies of the hydrophilic-hydrophobic polymer composites show that the particles of polyacrylamide, the dispersed phase, are separated by he network of the thin film of polystyrene, the continuous phase. This hydrophilic-hydrophobic polymer composites show higher permselectivity to water in the mixture of water-ethanol. The pervaporation experiment shows that the selectivity of the membrane ranges between 4-40 and increases with increasing enthanol concentration in the feed. The rate of permeation decreases with increasing ethanol concentration in the feed.

• Membrane Journal
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• v.22 no.6
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• pp.424-434
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• 2012

In this study, a ceramic membrane was prepared by CVD. Tube type alpha alumina support was used for substrate and added the Ga salt in intermediate layer. Synthesized method was counter diffusion CVD method at $650^{\circ}C$ with tetramethylorthosilane (TMOS). Gas permeation was measured at $600^{\circ}C$ using single-component $H_2$, $N_2$, $CO_2$ and $CH_4$. During the steam treatment, $H_2/N_2$ permselectivity of non-Ga silica membrane was decreased 926 to 829 at $600^{\circ}C$. On the other hand $H_2/N_2$ permselectivity of added Ga silica membrane was stable 910 to 904 at $600^{\circ}C$. These results show that the metal-doped membranes improved steam stability for gas separation.

• Korean Membrane Journal
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• v.6 no.1
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• pp.10-15
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• 2004

We developed a water-selective ceramic composite membrane for use as a dehydration membrane reactor for dimethylether (DME) synthesis from methanol. The membranes were modified on the porous stainless steel support by the sol-gel method accompanied by a suction process. The improved membrane modification process was effective in increasing the vapour permselectivity by removal of defects and pinholes. The optimized alumina/silica composite membrane exhibited a water permeance of 1.14${\times}$10$^{-7}$ mol/$m^2$.sec.Pa and a water/methanol selectivity of 8.4 at permeation temperature of 25$0^{\circ}C$. The catalytic reaction for DME synthesis from methanol using the membrane was performed at 23$0^{\circ}C$, and the reaction conversion was compared with that of the conventional fixed-bed reactor. The reaction conversion of the membrane reactor was much higher than that of the conventional fixed-bed reactor. The reaction conversion of the membrane reactor and the conventional fixed-bed reactor was 82.5 and 68.0%, respectively. This improvement of reaction efficiency can last if the water vapour produced in the reaction zone is removed continuously.

• Membrane Journal
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• v.33 no.6
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• pp.315-324
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• 2023

Ion-exchange membrane (IEM), is a key component that determines the performance of the electro-membrane processes. In this review, the latest research trends in improving the performance of IEMs used in various electro-membrane processes through modification using carbon-based and metal-based nanomaterials are investigated. The nanomaterials can be introduced into IEMs through various methods. In particular, carbon-based nanomaterials can strengthen their interaction with polymer chains by introducing additional functional groups through chemical modification. Through this, not only can the ion conductivity of IEM be improved, but also the permselectivity can be improved through the sieving effect through the layered structure. Meanwhile, metal-based nanomaterials can improve permselectivity through sieving properties using the difference in hydration radius between target ions and excluded ions within a membrane by using the property of having a layered or porous structure. In addition, depending on the characteristics of the binder used, ion conductivity can be improved through interaction between nanomaterials and binders. From this review, it can be seen that the properties of IEMs can be effectively controlled using carbon-based and metal-based nanomaterials and that research on this is important to greatly improve the performance of the electro-membrane process.

• Membrane Journal
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• v.33 no.5
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• pp.257-268
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• 2023

Membrane capacitive deionization (MCDI) is a variation of the conventional CDI process that can improve desalination efficiency by employing an ion-exchange membrane (IEM) together with a porous carbon electrode. The IEM is a key component that greatly affects the performance of MCDI. In this study, we attempted to derive the optimal fabricating factors for IEMs that can significantly improve the desalination efficiency of MCDI. For this purpose, pore-filled IEMs (PFIEMs) were then fabricated by filling the pores of the PE porous support film with monomers and carrying out in-situ photopolymerization. As a result of the experiment, the prepared PFIEMs showed excellent electrochemical properties that can be applied to various desalination and energy conversion processes. In addition, through the correlation analysis between MCDI performance and membrane characteristic parameters, it was found that controlling the degree of crosslinking of the membranes and maximizing permselectivity within a sufficiently low level of membrane electrical resistance are the most desirable membrane fabricating condition for improving MCDI performance.

• Textile Coloration and Finishing
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• v.3 no.2
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• pp.43-48
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• 1991

Cellulose acetate (CA) and poly-4-vinyl pyridine (PVP) in various weight proportions were mixed in a mixed solvent of trifluoroacetic acid: methylene chloride/6:4 (v:v). CA was miscible with PVP in that solvent system. CA/PVP/solvent show liquid crystal in a certain range of concentration and the nature of that liquid crystal was cholesteric. Films of the liquid crystal composite cast from the liquid crystal solutions of CA/PVP were tested in a viewpoint of biomembrane. Results show that considering permselectivity CA/PVP membrane is better than that of CA and CA/PVP membrane is closer to cell membrane.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.270-270
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• 2006

We have prepared polymer electrolyte membranes (PEMs) for DMFC from polymer mixture of poly(vinyl alcohol) and poly(vinyl alcohol-co-2-acrylamido-2-methylpropane sulfonic acid) (AP-2) changing the AP-2 content. The proton conductivity(${\Box}$) and methanol permeability(P) of the PEMs increase with increasing AP-2 content because the water content of the PEMs increases with increasing AP-2 content. The proton permselectivity of the PEMs, which is defined as ${\Box}={\Box}/P$, indicates higher values than that of $Nafion{(R)}$117.

• Proceedings of the Membrane Society of Korea Conference
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• 1996.10a
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• pp.47-48
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• 1996

최근 고분자 분리막을 이용한 기체 혼합물의 분리시 분리특성을 향상시키고자 하는 연구가 활발히 진행되고 있다. 그러나 고분자 막에 의해 기체를 분리할 경우 기체의 투과도와 선택도는 상반된 특성을 갖고 있어 투과도와 선택도 모두를 동시에 증가시키기 위한 분리막 소재의 개발 및 개선이 요구되며, 많은 연구자들이 이에 관련된 연구들을 수행하고 있다. 본 연구에서는 다양한 종류의 흡착제가 함유된 불균일상 기체분리막을 제조하여, 이막의 흡착제 함유량 변화에 따른 기체 투과성 및 발효가스중 특정성분 기체의 선택특성을 연구하였다. 본 연구는 김치를 포함한 우리나라 전통 식품의 밀폐포장내에서 발생되는 발효가스를 효율적으로 제거 또는 방출하기 위한 포장재 개발 연구에 대한 기초 연구로서 수행되었다.

• Korean Membrane Journal
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• v.7 no.1
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• pp.42-50
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• 2005

Among ceramic membranes developed to date, amorphous silica membranes are attractive for gas separation at elevated temperatures. Most of the silica membranes can be formed on a porous support by sol-gel or chemical vapor deposition (CVD) process. To improve gas permselectivity of the membrane, well-controlled pores having desired size and chemical affinity between permeates and membrane become important factors in the preparation of membranes. In this article, we review the literature and introduce our technologies on the microstructure to be solved and pore size control of silica membranes using sol-gel and CVD methods.