• Membrane Journal
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• v.26 no.5
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• pp.372-380
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• 2016

The present paper reports the effect of precursor alumina particle size on pore structure and single gas permeation properties of tubular ${\alpha}$-alumina supports, prepared by a combined process of slip casting and sintering. Pore diameter of as-prepared ${\alpha}$-alumina support was highly dependent on precursor ${\alpha}$-alumina particle size. Although, increase in the precursor particle size increases the pore diameter, but the porosity of ${\alpha}$-alumina support mainly control by sintering temperature. Sintering studies reveal that as sintering temperature increased porosity of support decreased. Single gas permeance results indicate that permence is proportional to the square of pore diameter and linearly to porosity. These dependencies revealed that gas permeation trough as-prepared ${\alpha}$-alumina support was governed by viscous flow mechanism. The present announces that precursor ${\alpha}$-alumina particle size and sintering temperature are key parameters to control gas permeantion properties of ${\alpha}$-alumina supports.

• Applied Chemistry for Engineering
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• v.19 no.4
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• pp.382-387
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• 2008

$Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ oxide was synthesized by polymerized complex method. Dense membrane of perovskite oxide was prepared using as-prepared powder by pressing and sintering at $1080^{\circ}C$. Leakage test was conducted on the membrane sealed by gold ring, Pyrex ring or Pyrex powder as a sealing material. The oxygen permeation flux of $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ membrane increased with increasing temperature and was $0.74mL/min{\cdot}cm^2$ at $900^{\circ}C$. In the case of the membrane applied by sealing material, oxygen permeation flux of the membrane using gold ring at $950^{\circ}C$ was higher than that using Pyrex materials because the undesired spreading of Pyrex glass materials in the membrane led to the reduction of effective permeation area. Microphotograph analysis results for the membrane after permeation test confirmedthe diffusion of Pyrex glass seal into the membrane.

• Journal of the Korean Society for Heat Treatment
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• v.26 no.3
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• pp.105-112
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• 2013

The microstructural changes of Fe-20Mn-12Cr-1Cu alloy have been studied during high temperature gas nitriding (HTGN) at the range of $1000^{\circ}C{\sim}1150^{\circ}C$ in an atmosphere of nitrogen gas. The mixed microstructure of austenite and ${\varepsilon}$-martensite of as-received alloy was changed to austenite single phase after HTGN treatment at the nitrogen-permeated surface layer, however the interior region that was not affected nitrogen permeation remained the structure of austenite and ${\varepsilon}$-martensite. With raising the HTGN treatment temperature, the concentration and permeation depth of nitrogen, which is known as the austenite stabilizing element, were increased. Accordingly, the depth of austenite single phase region was increased. The outmost surface of HTGN treated alloy at $1000^{\circ}C$ appeared Cr nitride. And this was in good agreement with the thermodynamically calculated phase diagram. The grain growth was delayed after HTGN treatment temperature ranges of $1000^{\circ}C{\sim}1100^{\circ}C$ due to the grain boundary precipitates. For the HTGN treatment temperature of $1150^{\circ}C$, the fine grain region was shown at the near surface due to the grain boundary precipitates, however, owing to the depletion of grain boundary precipitates, coarse grain was appeared at the depth far from the surface. This depletion may come from the strong affinity between nitrogen and substitutional element of Al and Ti leading the diffusion of these elements from interior to surface. Because of the nitrogen dissolution at the nitrogen-permeated surface layer by HTGN treatment, the surface hardness was increased above 150 Hv compared to the interior region that was consisted with the mixed microstructure of austenite and ${\varepsilon}$-martensite.

• Membrane Journal
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• v.19 no.2
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• pp.150-156
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• 2009

To improve the permselective efficiency of polysulfone membranes, the bromination was performed and then the resulting membranes were investigated in terms of membrane structures and gas transport characteristics. The brominated Polysulfone membranes were characterized by FT-IR, 1H-NMR, TGA, contact angle measurements, and gas permeation measurements were accomplished with He, $N_2,\;CO_2\;and\;O_2$. In general, the permeation rates were reduced while the selectivities increased as the bromination progressed.

• 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.

• Membrane Journal
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• v.22 no.5
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• pp.309-317
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• 2012

In this study, PTMSP/LDH composite membranes were prepared by the solution intercalation method with 1, 3, and 5 wt% LDH contents to PTMSP. To investigate the physico-chemical characteristics of composite membranes, the analytical methods such as FT-IR, TGA, XRD, UTM, and SEM have been utilized, and the gas permeability and selectivity properties of $H_2$, $N_2$, and $CO_2$ were evaluated. The permeability of the PTMSP/LDH composite membranes decreased as LDH content increased and the selectivity $H_2$ and $CO_2$ showed the maximum value at 5 wt% of LDH content. Permeability of PTMSP/LDH composite membrane increased as the gas permeation pressure increased. The difference of the increase in gas permeation pressure of the permeability of PTMSP/LDH composite membrane was slightly smaller than of PTMSP membrane.

• Membrane Journal
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• v.32 no.1
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• pp.74-82
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• 2022

The objective of this work was to investigate the gas permeation properties of CO₂ and CH₄ for PEBAX^®/TS-530 hybrid membranes and compare with pure PEBAX^®-1657 membrane. With FTIR and XRD it was possible to confirm that TS-530 was dispersed well in PEBAX^® matrix. Compared with pure PEBAX^® membrane, ideal separation factor for PEBAX^®/TS-530 (10 wt%) hybrid membrane was enhanced a little. As the amount of TS-530 was increased, the gas permeability coefficients of both CO₂ and CH₄ were increased, while the ideal separation factor was decreased. This results were explained by the reduction of crystallinity of polyamide block and interchain distance caused by introduction of inorganic nanoparticles. And fumed silica might tend to agglomerate, resulting in forming nonselective nanogaps in the hybrid materials, thus the diffusivity would be enhanced at the expense of diffusivity selectivity.

• 한국가스학회:학술대회논문집
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• 2003.10a
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• pp.114-119
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• 2003

• Membrane Journal
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• v.18 no.3
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• pp.256-259
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• 2008

In this study, graphite or zeolite 4A was mixed with poly(acrylonitrile-butadiene-strene) (ABS) to make hybrid films, and permeation characteristics of air and water vapor through these films were investigated. In all cases, gas permeabilities of hybrid films were lower than that of pure ABS films. The permeability decrease of oxygen was slightly larger than that of nitrogen, resulting in the little decrease of $O_2/N_2$ selectivity. In addition, the water vapor transfer rates (WVTR) of hybrid films were about half of ABS film's. The decrease of permeabilities may be owing to the increase of tortuosity for diffusion in hybrid films.

• Polymer(Korea)
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• v.24 no.5
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• pp.621-628
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• 2000

Microporous polypropylene (PP) membranes have the high chemical and corrosion resistance, the good mechanical properties and the thermal stability under high temperatures, but its application is restricted within narrow limits due to hydrophobicity of membranes. In order to impart permanent hydrophilicity to the PP microfiltration membrane, the radiation-induced graft of 2-hydroxyethyl methacrylate (HEMA) and acrylic acid (AAc) containing hydrophilic functional group onto the membrane has been studied. The effect of graft conditions such as reaction time, total radiation dose, reaction temperatures, acid compositions on graft yield was investigated. Modified PP membranes were shown to cause an increase in the gas flux. Oil emulsion permeation flux of both original PP membrane and modified PP membrane was examined.