• Proceedings of the Membrane Society of Korea Conference
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• 1999.07a
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• pp.15-18
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• 1999

A simple mathematical model for facilitated mass transport through a fixed site carrier membrane was derived by assuming an instantaneous, microscopic concentration (activity) fluctuation. The current model demonstrates that the facilitation factor depends on the extent of concentration fluctuation, the time scale ratios of diffusion to chemical reaction and the ratio of the carrier concentration to the solute solubility in matrix. The model was examined against the experimental data on oxygen transport in membranes containing metallo-porphyrin carriers, and the agreement was exceptional (within 10% error). The basic concept of this approach was applied to separate olefin from olefin/paraffin mixtures. A proprietaty carrier, developed here, resulted that the selectivity of propylene over propane was more than 120 and the propylene permeance exceed 40 gpu.

• Macromolecular Research
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• v.15 no.5
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• pp.459-464
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• 2007

Polymer electrolyte membranes, featuring ionic channels, were prepared from sulfonated dextran/ poly(vinyl alcohol) (sD/PVA) membranes. A stiff sulfated dextran was chosen as the route for ionic transport, since ionic sites are located along the stiff dextran main chain. The sD/PVA blend membranes were annealed and then chemically crosslinked. The characteristics of the crosslinked sD/PVA membranes were investigated to determine their suitability as proton exchange membranes. The proton conductivity was found to increase with increasing amounts of sD inside the membrane, which reached a maximum and then decreased when the sD content exceeded 30 wt%, while the methanol permeability increased with increasing sD content. The good dispersion of sD inside the membrane, which serves as an ionic channels mimic, played a significant role in proton transportation.

• Membrane Journal
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• v.13 no.2
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• pp.125-129
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• 2003

A remarkable separation performance of olefin/paraffin mixtures has been observed through facilitated olefin transport membranes consisting of silver ions dissolved in polymer matrices. In this research, valine, an amino acid, was introduced in poly (2-ethyl-2-oxazoline) (POZ)/$AgBF_4$ membranes to increase the separation performance. FT-IR spectra show that the cationic sites ($-NH_3^+$) of valine interact with the counter anion of the silver salt, resulting in the enhanced activity of the silver ions and consequently improved separation perfornance. Therefore, the $POZ/AgBF_4$ membranes containing valines exhibit the higher permeance as well as the higher selectivity of propylene/propane than those without valine.

• Composites Research
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• v.35 no.6
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• pp.402-411
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• 2022

In this study, the channels-contained hybrid membranes have been fabricated through the incorporation of glass fibers and GO sheets (GO/glass fibers, GG), or a mixture of chitosan/GO (CS/GO/glass fibers, CGG), as hybrid membranes using in organic dye removal. The material properties are well investigated the terms in the morphological, chemical, crystal, and thermal characterizations for verifying interactions in their formed structure. These hybrid membranes have been fitted well in pseudo-second order and Langmuir models that are associated with chemical adsorption and a monolayer approach, respectively. The highest adsorption ability of methylene blue and methyl orange reached 59.40 mg/g and 229.07 mg/g (GG); and 287.47 mg/g and 252.91 mg/g (CGG), which is more enhanced than that of previous GO-based other adsorbents. Moreover, the dye separation on these membranes could be favorable to superb sealing and trapping dye molecules from water instead of only the dye connection occurring on their surface, regarding the physically sieving effect. The membranes can also be reused within two and three adsorbing-desorbing cycles on the GG and CGG ones, respectively. These membranes can become future adsorbents to be applied for wastewater treatment due to their structural features.

• Membrane and Water Treatment
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• v.14 no.3
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• pp.115-120
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• 2023

The design theory for nanoporous filtration membranes needs to be established. The present study shows that the performance and technical advancement of nanoporous filtration membranes are determined by the fundamental parameter I (in the unit Watt^1/2) which is formulated as a function of the shear strength of the liquid-pore wall interface, the radius of the filtration pore, the membrane thickness, and the bulk dynamic viscosity of the flowing liquid. This parameter determines the critical power loss on a single filtration pore for initiating the wall slippage, which is important for the flux of the membrane. It also relates the membrane permeability to the power cost by the filtration pore. It is shown that for biological cellular membranes its values are on the scale 1.0E-8Watt^1/2, for mono-layer graphene membranes its values are on the scale 1.0E-9Watt^1/2, and for nanoporous membranes made of silica, silicon nitride or silicon carbonized its values are on the scale 1.0E-5Watt^1/2. The scale of the value of this parameter directly measures the level of the performance of a nanoporous filtration membrane. The carbon nanotube membrane has the similar performance with biological cellular membranes, as it also has the value of I on the scale 1.0E-8Watt^1/2.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.1
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• pp.28-37
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• 2022

In this study, we synthesized a poly(pheneylene oxide) (PPO)-based organic/inorganic composite membrane having silicotungstic acid (STA) for the development of an anion exchange membrane with excellent ionic conductivity and physicochemical stability. The organic/inorganic composite membranes were prepared by introducing different STA contents (0 wt%, 10 wt%, 30 wt%, and 50 wt%) into the quaternizaed(Q)-PPO matrix. The prepared anion exchange membranes were subjected to structural analysis by proton neclear magnetic resonance and Fourier transform infrared, and thermal behavior of membranes was confirmed by thermogravimetric analysis. Among the prepared composite membranes, the ion conductivity of Q-PPO/STA-50 (40.5 mS cm^-1) showed 1.46 times compared to that of the pristine membrane (27.6 mS cm^-1). Therefore, these results demonstrated that organic/inorganic composite membranes are promising candidates for application of anion exchange membranes.

• Membrane and Water Treatment
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• v.6 no.5
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• pp.365-378
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• 2015

Herein, the preparation of anion exchange membrane (AEM) from brominated poly(2,6-dimethyl 1,6-phenylene oxide) BPPO and dimethylaniline (DMA) by phase-inversion process is reported. Anion exchange membranes (AEMs) are prepared by varying the DMA contents. Prepared AEMs show high thermal stability, water uptake (WR) around 202% to 226%, dimensional change ratios of 1.5% to 2.6% and ion exchange capacities (IECs) of 0.34 mmol/g to 0.82 mmol/g with contact angle of $59.18^{\circ}$ to $65.15^{\circ}$. These membranes are porous in nature as confirmed by SEM observation. The porous property of membranes are important as it could reduce the resistance of transportation of ions across the membranes. They have been used in diffusion dialysis (DD) process for recovery of hydrochloric acid (HCl) from the mixture of HCl and ferrous chloride ($FeCl_2$). Presence of $-N+(CH_3)_2C_6H_5Br^-$ as a functional group in membrane matrix facilitates its applications in DD process. The dialysis coefficients of hydrochloric acid ($U_H$) of the membranes are in range of 0.0016 m/h to 0.14 m/h and the separation factors (S) are in range of 2.09 to 7.32 in the $HCl/FeCl_2$ system at room temperature. The porous membrane structure and presence of amine functional group are responsible for the mechanism of diffusion dialysis (DD).

• Journal of Periodontal and Implant Science
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• v.27 no.1
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• pp.1-17
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• 1997

Tetracycline is known to be effective in eliminating periodontopathogens and have collagenolytic activity. This study was performed to observe the desorption kinetics and structural changes of tetracycline-treated barrier membranes for guided tissue regeneration. Four kinds of barrier membranes were tested : $Tefgen^{(R)}$(American Custom Medical, USA) and $Gore-Tex^{(R)}$(W.L. Gore & Associates Inc., USA) as nonresorbable membranes ; Resolut(polyglycolide & polylactide copolymer, W.L. Gore & Associates Inc., USA) and $Biomend^{(R)}$(collagen, Collatec Co., USA) as resorbable membranes. The membranes were cut into discs(diameter : 4mm) and were immersed in 5% tridodecylmethylammonium chloride(TIMAC) ethanol and air-dried. The membrane discs were absorbed with $100{\mu}g/ml tetracycline solution(pH8) for one minute and dried. For desorption kinetics, TC treated discs were immersed in phosphate buffered saline solution (PBS, pH 7.4). PBS was exchanged daily and TC concentration was measured by absorbance at 276nm on UV spectrophotometer. To measure remaining antibacterial activity, discs of 1 day to 4 weeks after desorption were placed on Mueller Hinton agar containing Bacillus cereus and incubated aerobically in $37^{\circ}C$ for twelve hours and the inhibition diameters were measured. To observe the structural change of membranes after TIMAC treatment or immersion in PBS, the membrane discs were examined under SEM. The results were as follows : 1. Total amounts of TC absorbed into membrane discs($0.7536mm^2$) were $2000{\mu}g$, $1800{\mu}g$, $2625{\mu}g$ and $2499{\mu}g$ for $Tefgen^{(R)}$, $Gore-Tex^{(R)}$, $Biomend^{(R)}$ and $Resolut^{(R)}$. 2. The concentration of TC released from barrier membrane discs was maintained over $4{\mu}g/ml$ until the fifth day in nonresorbable membranes and $Resolut^{(R)}$, but until the fourth day in $Biomend^{(R)}$, Until the ninth day in nonresorbable membranes and until the seventh day in resorbable membranes, the TC concentration was maintained over $1{mu}g/ml$. 3. The four membrane discs in the first day showed similar size of inhibition zone. One to four weeks later, the inhibition zone was much smaller in resorbable membrane discs than nonresorbable membrane discs. 4. Any structural change due to treatment of TIMAC was not observed on the nonresorbable membranes. $Resolut^{(R)}$ did not show any structural change except fibrillar loosening during immersion period, but Biomend showed destruction of membrane structure from the first week of immersion. This study indicates that tetracycline treated barrier membranes lead to the sustained release of tetracycline for over 7 days. This slow release pattern of tetracycline may contribute to the favorable clinical outcome of guided tissue regeneration.

• Proceedings of the Membrane Society of Korea Conference
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• 2003.05a
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• pp.95-98
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• 2003

• Proceedings of the Membrane Society of Korea Conference
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• 2003.05a
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• pp.71-74
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• 2003