• Membrane Journal
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• v.31 no.5
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• pp.351-362
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• 2021

All-vanadium redox flow battery (VRFB) is one of the promising high-capacity energy storage technologies. The ion-exchange membrane (IEM) is a key component influencing the charge-discharge performance and durability of VRFB. In this study, a pore-filled anion-exchange membrane (PFAEM) was fabricated by filling the pores of porous polytetrafluoroethylene (PTFE) support with excellent physical and chemical stability to compensate for the shortcomings of the existing hydrocarbon-based IEMs. The use of a thin porous PTFE support significantly lowered the electrical resistance, and the use of the PTFE support and the introduction of a fluorine moiety into the filling ionomer significantly improved the oxidation stability of the membrane. As a result of the evaluation of the charge-discharge performance, the higher the current efficiency was seen by increasing the fluorine content in the PFAEM, and the superior voltage and energy efficiencies were shown owing to the lower electrical resistance compared to the commercial membrane. In addition, it was confirmed that the use of a hydrophobic PTFE support is more preferable in terms of oxidation stability and charge-discharge performance.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.599-600
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• 2006

This paper described the state of art of porous metal materials, the typical manufacturing technologies and performances of sintered metal porous materials, with emphasis on the recent research achievements of CISRI in development of porous metal materials. High performance porous metal materials, such as metallic membrane, sub-micron asymmetric composite porous metal, large dimensional and structure complicated porous metal aeration cones and tube, metallic catalytic filter elements, lotus-type porous materials, etc, have been developed. Their applications in energy industry, petrochemical industry, clean coal process and other industrial fields were introduced and discussed.

• Membrane Journal
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• v.31 no.1
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• pp.52-60
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• 2021

When preparing calcium alginate microspheres using rotating membrane emulsification that rotates SPG (Shirasu porous glass) tubular membrane in the continuous phase, the optimal conditions of rotating membrane emulsification process parameters for producing monodisperse microspheres were determined. We determined the effects of process parameters of rotating membrane emulsification (the rotating speed of membrane module, the transmembrane pressure, the ratio of dispersed phase to continuous phase, the alginate concentration, the emulsifier concentration, the stabilizer concentration, the crosslinking agent concentration, and the membrane pore size) on the mean size and size distribution of alginate microspheres. As a result, the size of the microspheres decreased as the rotating speed of membrane module, the emulsifier concentration, and the crosslinking agent concentration increased among the process parameters of rotating membrane emulsification. On the contrary, as the ratio of dispersed phase to continuous phase, the transmembrane pressure, and the alginate concentration increased, the size of the microspheres increased. In the rotating membrane emulsification using an SPG membrane with a pore size of 3.2 ㎛, it was possible to finally prepare monodisperse alginate microspheres with a particle size of 4.5 ㎛ through the control of process parameters.

• Membrane Journal
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• v.19 no.2
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• pp.113-121
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• 2009

Porous affinity chitosan and chitin membranes with good mechanical strength and high protein binding capacity were prepared by using silica particles as porogen. The maximum binding capacity of affinity chitosan membrane for BSA protein is 21.8mg/mL, and that of affinity chitin membrane for lysozyme enzyme is 26.1mg/mL. Chromatographic separations of BSA and lysozyme proteins using the porous affinity chitosan and chitin membranes were performed with change of the flow rate, loading amount and concentration of protein loading solutions. Protein eluted amount and binding yield were calculated from the filtration chromatograms consisted of loading/washing/elution sequences. Protein binding amount and yield were increased with decreasing of flow rate, increasing of loading amount and concentration of protein loading solutions. Those results suggest that the porous chitosan and chitin membranes prepared by using silica particles as porogen are suitable in affinity filtration chromatography for large scale separation of proteins.

• Journal of Environmental Science International
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• v.9 no.4
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• pp.311-318
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• 2000

To improve $CO_2$pemselectivity, a modified silica membrane was prepared by chemical vapor deposition with tetraethoxysilane(TEOS)-ethanol-water, and TEOS-ethanol-water-HCI solution at 300-$600^{\circ}C$. The silica was effectively deposited in the mesopores of a ${\gamma}$-alumina film coated on a porous $\alpha$-alumina tube by evacuating the reactants through the porous wall. In this membrane, $CO_2$interacts, to some extent, with the pore wall, and $CO_2$/$N_2$selectivity then exceeds the value of the Knudsen diffusion mechanism, while the membrane derived from TEOS alone has no $CO_2$selectivity. The silica membrane prepared from TEOS-ethanol-water-HCI solution showed that $CO_2$permeance was $2.5$\times$10^{-7}mol/s^{-1}.m^{-2}.Pa^{-1} at 30{\circ}C$ and $CO_2$/$N_2$selectivity was approximately 3. The $CO_2$permeance and selectivity was improved by enlarging the surface diffusion with modification of chemical affinity of the silica pores.

• Membrane Journal
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• v.20 no.2
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• pp.151-158
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• 2010

This paper presents the synthesis of ampholyte immobilized hollow-fiber membranes and adsorption characteristic of metallic ions. This is prepared by radiation induced grafting polymerization of an epoxy group containing Glycidyl methacrylate (GMA) onto an existing polyethylene porous hollow-fiber membrane. Ampholyte ion-exchanged alkalic group, $-NH_2$ (amine function) of Taurine (TAU) is reacted with glycidyl of GMA for the synthesis of stable membrane. However, Sodium sulfite (SS) membrane is also prepared by making chemical bonds with GMA of porous hollow-fiber membrane for the comparison of adsorption characteristic of metallic ions. These are called as TAU and SS membranes, respectively. It is shown that TAU membrane shows a steady flux, 0.9 m/h regardless of the density of TAU, while the flux of SS membrane decreases rapidly as the density of $SO_3H$ group increases. SS membrane showed a negligible flux. TAU membrane with the density 0.8 mmol/g shows the amount of metallic ions adsorbed in the following order, Cu > Cd > Mg > Sb > Pb. In general, TAU membrane with high density and reaction time showed the high amount of metallic ions adsorbed and flux.

• 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.11
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• pp.963-968
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• 2002

In this work, porous silicon (PS) layer is investigated as a sensing material to detect organic vapors such as ethanol (called alcohol), methanol, and acetone in low concentrations. To do this, PS sensors were fabricated. They have a membrane structure and comb-type electrodes were used to detect the change of electrical resistance effectively. PS layer on Si substrates was formed by anodization in HF solution of 25%. From fabricated sensors, current-voltage (Ⅰ-Ⅴ) curves were measured for gases evaporated from 0.1 to 0.5% organic solution concentrations at 36$\^{C}$. As the result, all curves showed rectifying behavior due to a diode structure between Si and the PS layer. The conductance of most sensors increased largely at high voltage of 5V, but the built-in potential on the measured Ⅰ-Ⅴ curve was lowered inversely by the adsorption effect of the organic vapors with high dipole moment.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.2
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• pp.21-27
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• 2014

Recently, various biochip environments have been presented. In this study, a novel transparent film with porous membrane windows, which is an essential component in a co-cultured biochip environment, is fabricated using spin-coating, 3D printing, and electrospinning processes. In detail, a transparent polystyrene film was fabricated by means of the spin-coating process followed bywindow cutting, after which apolycaprolactone-chloroform solution was deposited along the window edge to introduce an adhesion layer between the PS film and the PCL nanofibers. Nanofibers were electrospun into the window region using a direct-write electrospinning method. Consequently, it was demonstrated that the fabricated window film could be used in a co-culture biochip environment.

• Journal of the Korean institute of surface engineering
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• v.15 no.2
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• pp.69-76
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• 1982

With a view to manufacturing membranes for separation of gas mixtures, Al foils were anodized in a 2% oxalic-acid electrolyte at 40V and 80V. When anodizing was completed and Barrier layer existed at the extreme back site of the foil, the anodized foil was made to react with only electrolyte, with switching off the electric power. When the size and density of pores were changed through voltage change, the membr-anes did not show large difference in the permeability. Reacting with electrolyte, the existing Barrier layer turns into porous layer. During this process, several small pores grow from one relatively large pore, getting to the back site. The number and size of the small pores getting to the back surface increase as time passing. This change of Barrier layer into porous layer is thought to be directly related to the permeability change of the membranes. The selectivity of an anodized Al membrane was not related to the voltage change, and was high, being similar to the theoretical selctivity of metallic membranes, according to my observation.