• Korean Journal of Food Science and Technology
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• v.29 no.2
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• pp.302-308
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• 1997

${\beta}-Cyclodextrin\;({\beta}-CD)$ polymers were prepared using epichlorohydrin as a cross linking agent. The polymers were separated into ${\beta}-CD$ soluble polymer $({\beta}-CD\;SP)$ and ${\beta}-CD$ insoluble polymer $({\beta}-CD\;ISP)$ on a 10,000 molecular weight cut-off membrane (YM 10). Optimum separation conditions in the YM 10 were: transmembrane pressure 51.7 kPa, separation temperature $35^{\circ}C$, and volume concentration ratio 10. The flux was $0.025\;mL/cm^{2}/min$ under the optimum conditions. Gel permeation chromatography indicated that ${\beta}-CD\;SP\;and\;{\beta}-CD\;ISP$ had a degree of polymerization of $2{\sim}8$ and over 10, respectively. The formation of an inclusion complex with hydrophobic compounds such as 4-dimethylaminoazobenzene, methyl red, and naringin was compared among ${\beta}-CD,\;{\beta}-CD\;SP\;and\;{\beta}-CD\;ISP$. The molar absorptivity for the two chromatic compounds was increased and the absorption peak was shifted in the presence of ${\beta}-CD$ polymers. Naringin, the principal flavonoid bitter tasting component of citrus fruit, had a low water solubility. The solubility of naringin was increased through the formation of an inclusion complex with ${\beta}-CD$ polymers. There was no significant difference in the formation of an inclusion complex between ${\beta}-CD\;SP\;and\;{\beta}-CD\;ISP$. Reduction of the bitter components from citrus products was shown to be possible when employing ${\beta}-CD\;SP$, while the usage of ${\beta}-CD$ monomer has been limited due to the low water solubility.

• Membrane Journal
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• v.1 no.1
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• pp.65-77
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• 1991

The perstraction of ethanol and acetic acid were performed for three systems of xylene-acetic acid-water, MIBK-ethanol-water, and TBP-ethanol-water, The operating variables were pressure difference between aqueous and organic phase, and superfial velocities of aqueous and organic phases. The tortuosities of PP hollow fiber membrane of Celgard X10-400 and PTFE hollow fober membrane of Tex TA001 were found to be 1.82 and 1.43 respectively, They were obtained from mass tranfer coeffidents in membrane phase for xylene-acetic acid-water systems. The permeation flux and overall mass transfer coefficient for MIBK-ethanol-water system are larger than those for TBP-ethanol-water system. This tendency is magnified with increasing the superficial velocity of organic phase. Overall mass transfer coefficient($K_o$) increases nonlinearly with the increase of superficial velocity of organic phase($V_{or}$), and the relationship between $K_o$ and $V_{or}$ is that $K_o {\propto} V_{or}^{-0.35}$. For ethanol perstraetion using the hollow fiber membrane of Gore Tex TA001, the mass transfer in membrane phase is the rate-limiting step.

• Membrane Journal
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• v.30 no.4
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• pp.269-275
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• 2020

In this study, CO₂ separation experiment was performed on a CH₄/CO₂ mixed gas using a ceramic hollow fiber membrane contactor (HFMC). In order to fabricate high-performance HFMC, experiments were conducted to manufacture high-permeability hollow fiber membranes, and the prepared hollow fiber membranes were evaluated through N₂ gas permeation experiments. HFMC for CH₄/CO₂ mixed gas separation was manufactured using the manufactured high-permeability hollow fiber membrane. In the experiment, mixed gas of CH₄/CO₂ (34.5% CO₂, CH₄ balance) and monoetanolamine (MEA) was used, and the effect of CO₂ removal efficiency on the flow rate of the absorbent was evaluated. The CO₂ removal efficiency increased as the liquid flow rate increased, and the CO₂ absorption flux also increased with the liquid flow rate.

• Membrane Journal
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• v.8 no.2
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• pp.77-85
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• 1998

To treat effectively EDIR (electrodeposition ion removal) wastewater in terms of CO$_{Mn}$ 1,500~2,000 ppm generated from aluminum painting process, a RO (reverse osmosis) process was designed and installed to recover and reuse the concentrated solvent sent back to the electrocodeposition tank while the permeate reused as rinse water. A RO system in which three polyamide-spiral wound modules ($102\Phi \times 1,016L$ mm) connnected in series had been running to treat 20 m$^3$ in waste volume in 3 days batch operation at the condition of system recovery of 30 %, applied pressure 11.5 $kg_f/cm^2$ and room temperature. During 42 hours continuous operation leading to 5-fold decrease in waste volume, nearly constant permeation flux of 390 l/m$^2$-hr was maintained and the permeate with average CO$_{Mn}$, 300 ppm was obtained which could be used for washing the remaining paint solution in ion-exchange tower instead of demineralized water. Also COD$_{Mn}$ rejection as a function of running time was observed to be in the range of 78~87 % and the observed solvent rejections for ethyl cellusolve, buthyl cellusolve and n-butanol were 79 %, 87 % and 70 %, respectively.

• Membrane Journal
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• v.31 no.5
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• pp.343-350
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• 2021

In this study the suction pressure was measured with respect to operational time by submersing the multi-bore capillary membrane module in membrane bioreactor(MBR). The hexagonal shape capillary module which has the nominal pore size of 0.2 ㎛, outer diameter of 6.4 or 4.2 mm was immersed in MLSS 8,000 mg/L active sludge aqueous solution, and confirmed changes with respect to permeation flux and air flow rate. It was operated by the filtration/relaxation(FR), FR with backwashing(FR/BW), and sinusoidal flux continuous operation(SFCO) modes. The suction pressure for the SFCO and FR modes was lower at 30 and 50 L/m²·hr, respectively. In addition, the suction pressure of the module with a small outer diameter was relatively low. The suction pressure of a large outer diameter was greatly increased, but it could be reduced by more than 40% by backwashing.

• Membrane Journal
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• v.34 no.1
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• pp.50-57
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• 2024

In this experiment, Pd-Ag-Cu membrane was manufactured using electroless plating on an α-Al₂O₃ support. Pd, Ag and Cu were each coated on the surface of the support through electroless plating and heat treatment was performed for 18 h at 500℃ in H₂ in the middle of electroless plating to form Pd alloy. The surface of the Pd-Ag-Cu membrane was observed through Scanning Electron Microscopy (SEM), and the thickness of the Pd membrane was measured to be 7.82 ㎛ and the thickness of the Pd-Ag-Cu membrane was measured to be 3.54 ㎛. Energy dispersive X-ray spectroscopy and X-ray diffraction analysis confirmed the formation of a Pd-Ag-Cu alloy with a composition of Pd-78wt%, Ag-8.81wt% and Cu-13.19wt%. The gas permeation experiment was conducted under the conditions of 350~450℃ and 1~4 bar in H₂ single gas and H₂/N₂ mixed gas. The maximum H₂ flux of the hydrogen separation membrane measured in H₂ single gas is 74.16 ml/cm²·min at 450℃ and 4 bar for the Pd membrane and 113.64 ml/cm²·min at 450℃ and 4 bar for the Pd-Ag-Cu membrane. In the case of the separation factor measured in H₂/N₂ mixed gas, separation factors of 2437 and 11032 were measured at 450℃ and 4 bar.

• Journal of the Korean Electrochemical Society
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• v.6 no.1
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• pp.59-64
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• 2003

We fabricated mixed ionic-electronic conducting membranes, $CH_4\;Using\;{0.7}Sr_{0.3}Ga_{0.6}Fe_{0.4}O_{3-\delta}$, by solid state reaction method for solid oxide fuel cell. The membranes consisted of single perovskite phase and exhibited high relative density, $>95\%$. We coated $La_{0.6}Sr_{0.4}CoO_{3-\delta}$ layer using screen printing method in order to improve surface reactivity of the $La_{0.7}Sr_{0.3}Ga_{0.6}Fe_{0.4}O_{3-\delta}$. As a result, the oxygen permeation flux of the coated $La_{0.7}Sr_{0.3}Ga_{0.6}Fe_{0.4}O_{3-\delta}$ showed higher value, $0.5ml/min{\cdot}cm^2\;at\;950^{\circ}C$ than the uncoated one. Higher oxygen permeation was observed in the porously coated Lao $La_{0.7}Sr_{0.3}Ga_{0.6}Fe_{0.4}O_{3-\delta}$membranes with larger grain sizes. Syngas, $CO+H_2$, was successfully obtained from methane gas, $CH_4$, using the $La_{0.6}Sr_{0.4}CoO_{3-\delta}$ coated $La_{0.7}Sr_{0.3}Ga_{0.6}Fe_{0.4}O_{3-\delta}$, with over $40\%\;of\;CH_4$ conversion and syngas yield. $La_{0.7}Sr_{0.3}Ga_{0.6}Fe_{0.4}O_{3-\delta}$ membrane was stable even when it was exposed to the reducing environment, methane, for 600 hrs at $950^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.39 no.10
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• pp.994-1000
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• 2002

Oxygen permeability and the mechanical properties of mixed ionic-electronic conductive $La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_{3-{\delta}}$ perovskite-type membrane, fabricated by solid state reaction, were investigated with regard to microstructure. The microstructure of the membrane was controlled by changing the sintering temperature and holding time. The average grain size and relative density were evaluated as a function of sintering conditions. As the fraction of grain boundary decreased, oxygen permeability showed a tendency to increase. Especially the maximum oxygen flux of 0.37 ml/$cm^2$${\cdot}$min was measured for the specimen sintered at 1300${\circ}C$ for 10 h, which has high density and relatively large grain size. Fracture strength was dependent on the relative density of sintered body, while fracture toughness increased with average grain size.

• Journal of the Korean GEO-environmental Society
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• v.11 no.1
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• pp.5-11
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• 2010

The objective of this study is to evaluate the effect of operational parameters such as rotation speed and vibrating milling time for the fabrication of photocatalytic $TiO_2$ thin film using aerosol deposition methods. $TiO_2$ powders produced in the range of 1,000-3,000 rpm of rotation speed of centrifugal separator are ineffective on the fabrication of $TiO_2$ thin film by aerosol deposition due to the problem of nozzle powder jam. $TiO_2$ powders controlled by vibrating milling had about 420 nm of average diameter after 2 hr of vibrating milling time. The result of XRD analysis indicated that $TiO_2$ powders had a anatase phase. Vibrating milling methods was considered to be an effective pre-treatment process for $TiO_2$ powder control. Consequently $TiO_2$ photocatalytic thin film with dispersion of anatase crystallites controled by vibrating milling was successfully fabricated by aerosol deposition. The permeation flux of $TiO_2$ photocatalytic thin film with the immobilized $TiO_2$ powder was higher than that of suspended $TiO_2$ powder. Therefore, $TiO_2$ photocatalytic thin film promises to be one of the effective methods for enhancing filtration performance for the treatment of organic pollutants.

• Membrane Journal
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• v.21 no.2
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• pp.177-192
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• 2011

Hollow fiber membrane using CTA polymers were prepared by the phase separation method for the separation and purification of biogas and the hollow fiber gas separation membrane modules with the effective surface area of 0.17 $m^2$ were prepared. The pure gas permeation properties of membrane modules for methane, oxygen and carbon dioxide were measured. The permeance of $CO_2$ and $CH_4$were 0.46 GPU and 18.52 GPU, respectively, therefore, the high $CO_2$/$CH_4$ selectivity of 40.4 was obtained. The separation and purification test for 4 different simulated mixed gases were carried out after the pure gas test and the gas concentration and flux of the permeate at the various stage-cut were measured from the 1 stage, 2 stage, and 3 stage cascade of membrane modules. In the 1 stage test, the concentration of $CH_4$ increased as the increase of the stage-cut, while the $CH_4$ recovery efficiency ratio decreased. In the 2 stage test, the $CH_4$ recovery efficiency ratio increased compared to the 1 stage. The 3 stage test was employed to reduce the loss of $CH_4$ in biogas and the result showed less than 5% of $CH_4$ recovery loss.