• Food Science and Preservation
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• v.5 no.3
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• pp.239-246
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• 1998

Polyimide membrane system was designed for manufacturing nitrogen-enriched gas, and basic technical data was suggested for appling this system to controlled atmosphere storage. The permeability characteristics of pure oxygen and nitrogen could be explained by dual-mode sorption model. There was substantial decrease in the permeation rates of oxygen, which is the more permeable gas, through the polyimide membrane due to the presence of nitrogen in comparison with pure oxygen. However, the permeation rates of nitrogen was increased by the presence of oxygen. The ideal separation factor was in the range of 5 to 6 in the range of temperature and pressure difference studied, and the separation factor of air was lower than the ideal separation factor. The increase of ideal separation factor with increasing temperature is due to the fact that the activation energy for oxygen is larger than that for nitrogen. Nitrogen concentration decreased rapidly with increasing product recovery, and it was found that this is a major operating factor to obtain nitrogen concentration required for controlled atmosphere storage. A relation equation, by which nitrogen concentration in storehouse can be predicted, was suggested under the establishment of a hypothetical model for controlled atmosphere storage process using polyimide membrane system.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.09a
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• pp.73-85
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• 1995

The asymmetric hollow fiber membranes were prepared by the wet spining of polyetherimide dope solution and the effect of hollow fiber structures on the permeation characteristics of carbon dioxide and nitrogen gases through these membrane were investigated. As the concentration of the $\gamma$-butyrolactone (GBL) in dope solution, acting as a swelling agent was increased, the structure of hollow fiber was changed from the finger to sponge type. The permeabilities of gases (CO$_{2}$, N$_{2}$) through these membrane were measured over the wide range of pressure under different temperature. The effect of water vapor on the permeabilities of gases was also investigated. The measured permeabilities showed the different characteristics depending on the structure of membranes. It was found that the flow through the pores were dominant over the polymers matrix. Blocking effect by water vapor in the pores of skin layer greatly improved the ideal separation factor of carbon dioxide/nitrogen.

• Macromolecular Research
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• v.10 no.2
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• pp.80-84
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• 2002

Silver species other than the silver ion were formed by UV irradiation on polymer electrolyte membranes containing silver salts and their effect on complexation behavior between the silver and olefin was investigated through the separation performance of olefin/paraffin mixtures. The ideal propylene/propane separation factor reached 350 and the separation coefficient was ca.15 due to the high loading amount of silver ions into poly(2-ethyl-2-oxazoline) (POZ) without UV irradiation. On UV irradiation either in air or under nitrogen, the silver-POZ membranes became yellow-brown initially due to the formation of colloidal silver particles, and finally black and metal-like luster. Even when Ag$^{+}$ was converted, to some extent, to Ag$^{\circ}$ by UV irradiation in air at the early stage, the separation coefficient of olefin/paraffin mixtures was maintained. This suggests that silver species other than the silver ion is active for olefin carrier for facilitated transport. Meanwhile the steady decrease of the separation coefficient was observed in the silver/POZ membranes irradiated under $N_2$. It is suggested that the reduction of silver ions in POZ goes through a different photoreduction mechanism with UV irradiation depending on the environment.t.

• Journal of Industrial Technology
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• v.14
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• pp.141-153
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• 1994

폴리이미드 분리막에 의한 $CCl_2F_2/Air$ 혼합물의 분리특성에 관하여 온도, 압력, stage cut(${\theta}$), 주입기체 조성등의 영향을 규명하였다. 본 연구의 실험범위 내에서 이상분리인자(ideal separation factor)는 600-200이었으며, glassy polymer인 폴리이미드 분리막에 대하여 투과도가 높은 air의 투과도는 $CCl_2F_2$ (dichlorodifluoromethane, CFC-12)에 의하여 상당히 감소함을 알 수 있었다. 그러나, 폴리이미드 분리막에 대한 투과도가 낮은 $CCl_2F_2$의 투과도는 air에 의하여 투과도가 증가하였다. 또한, 수학적 모델에 의한 예측치가 실험치와 잘 일치됨을 알 수 있었다.

• 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.

• Macromolecular Research
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• v.16 no.6
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• pp.555-560
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• 2008

A series of hydroxyl-group containing polyimides (HPIs) were prepared in order to investigate the structure-gas permeation property relationship. Each polymer membrane had structural characteristics that varied according to the dianhydride monomers. The imidization processes were monitored using spectroscopic and thermog-ravimetric analyses. The single gas permeability of He, $H_2$, $CO_2$, $O_2$, $N_2$ and $CH_4$ were measured and compared in order to determine the effect of the polymer structure and functional -OH groups on the gas transport properties. Surprisingly, the ideal selectivity of $CO_2/CH_4$ and $H_2/CH_4$ increased with increasing level of -OH incorporation, which affected the diffusion of $H_2$ or the solubility of $CO_2$ in HPIs. For $H_2/CH_4$ separation, the difference in the diffusion coefficients of $H_2$ and $CH_4$ was the main factor for improving the performance without showing any changes in the solubility coefficients. However, the solubility coefficient of $CO_2$ in the HPIs increased at least four fold compared with the conventional polyimide membranes depending on the polymer structures. Based on these results, the polymer membranes modified with -OH groups in the polymer backbone showed favorable gas permeation and separation performance.

• Membrane Journal
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• v.16 no.2
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• pp.123-132
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• 2006

The PTMSP-silica-PEI composite membranes were synthesized from tetraethoxysilane (TEOS) and poly (1-trimethylsilyl-1-propyne) (PTMSP) by sol-gel process. The PTMSP-silica nanocomposite membranes were characterized by $^1H-NMR$, FT-IR, TGA, XPS, SEM, GPC and gas permeation measurements were accomplished with $H_2,\;O_2,\;N_2,\;CO_2,\;CH_4$. The gases permeability increased with increasing TEOS content. Both the permeability and selectivity of $H_2,\;CH_4$ increased to 15 wt% TEOS. While the permeability of $O_2,\;CO_2$ increased without decrease of selectivity.

• Membrane Journal
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• v.23 no.2
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• pp.144-150
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• 2013

In order to increase the permeabilities of $N_2$, $O_2$, $CH_4$, $CO_2$, $SO_2$, Poly (ether block amides) (PEBAX) 3533 and its blended membranes with Poly (ethylene glycol) (PEG) of molecular weight 400 were prepared. The contents of PEG400 were 20%, 40%, and 50% and this membranes were characterized in terms of permeability for $N_2$, $O_2$, $CH_4$, $CO_2$, $SO_2$ gases and also diffusivity and solubility as well by using the time-lag gas separation apparatus. As expected, the permeabilities incerased as the contents of PEG400 increased. For the ideal selectivity, there is no big difference in values of between PEBAX 3533 and PEBAX/PEG400 membranes. The increase of permeabilities is due to the increases of solubilities of gases in question and this will be explained in more detail.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.10a
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• pp.73-74
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• 1997

1. 서론 : 공기중의 산소와 질소를 분리하여 공기 중에 21% 함유된 산소를 보다 높은 농도(21%이상)로 농축하기 위한 기초자료로서 건조 산소(dry O$_2$)와 건조 질소(dry N$_2$)의 투과도를 측정하였다. 그러나 공기중에는 항상 수분이 포함되어 있으므로 공기 중에 함유된 수분(water vapour)에 의한 산소 투과도와 질소 투과도의 변화를 측정하기 위하여 상대숩도 및 압력차이에 따른 영향을 고찰하였다. 그리고 분리막공정에서 순수기체의 막에 대한 투과도를 알 수 있다면 기체 혼합물에 대한 이상분리인자(ideal separation factor)를 알 수 있으며, 이를 이용하여 분리막의 분리 성능 예측이 가능하므로 투과도 예측식을 얻는다는 것은 매우 중요하다. 본 연구에서는 counter-current model을 이용하여 기체 혼합물의 투과도를 예측하고 실험치와 비교하였다.

• Membrane Journal
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• v.9 no.1
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• pp.25-35
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• 1999

The sorption and permeation experiments with $O_2$ and $N_2$ were performed with poly sulfone hollow-fiber membrane to obtain oxygen-enriched air. Sorption of $O_2$ on poly sulfone membrane was 1.5'||'&'||'not;2.0 times higher than that of N2. Sorption of oxygen and nitrogen in poly sulfone membrane was described satisfactorily with "dual-mode sorption model". In the low pressure range below 3kgr!cm', about 85% of total sorption was Langmuir-type sorption and only 15% was Henry-type sorption. In the higher pressure above 3kgf/${cm}^2$, Langmuir sorption sites became almost saturated and reached asymptote, and the increase in total sorption with pressurizing might be due to the Henry~type sorption. The ideal separation factor ( P $O_2$/ P $N_2$) was in the range of 2~4, while the actual separation factor for the mixture was reduced to the value of 1.7~2.2.2.2.