• Membrane Journal
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• v.30 no.1
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• pp.46-56
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• 2020

In this study, poly (ether-block-amide) (PEBAX)/poly (ethylene) glycoldiacrylate (PEGDA)/zeolitic imidazolate framework-8 (ZIF-8)-polyethersulfone (PES) composite membranes were prepared. The gas permeation properties of N₂ and CO₂ were investigated for each composite membrane. First, the gas permeability in the PEBAX/PEGDA-PES composite membrane decreased with increasing PEGDA content for each molecular weight at PEGDA250, PEGDA575, and PEGDA-700 g/mol. The CO₂/N₂ selectivity showed a constant value and gradually increased with increasing PEGDA content after 30 wt% PEGDA, and PEBAX/PEGDA250 50 wt%-PES prepared by adding PEGDA250 g/mol 50 wt% showed a selectivity of 15.1. This is because as the PEGDA content increases, the number of diacrylate groups increases, and the CO₂ affinity due to the ether structure of PEGDA increases. Gas permeation properties according to ZIF-8 were investigated for composite membranes of PEGDA 0 to 30 wt%, with CO₂/N₂ selectivity almost constant for each molecular weight. The permeability of N₂ and CO₂ gradually increased with increasing ZIF-8 content, and CO₂/N₂ selectivity was the highest at 3.4 in PEBAX/PEGDA250 g/mol 30 wt%/ZIF-8 20 wt%-PES composite membrane.

• Membrane Journal
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• v.27 no.4
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• pp.319-327
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• 2017

Chitosan/Pebax composite membranes were prepared with 1 : 1, 1 : 2, 1 : 10, 1 : 30 mass ratio of pebax and chitosan. Gas permeation test were carried out under pressure $6kgf/cm^2$, 35, $45^{\circ}C$ and $65^{\circ}C$ at different temperatures. The gas permeability and selectivity ($CO_2/N_2$) of $N_2$ and $CO_2$ for the Chitosan/Pebax composite membranes were investigated. As the amount of Pebax added to chitosan was increased the gas permeability of both $N_2$ and $CO_2$ increased. The selectivity ($CO_2/N_2$) was 6.9~44.3 in the Chitosan/Pebax composite membranes. With the increase of contents of Pebax and the decrease of temperature, the selectivity ($CO_2/N_2$) increased.

• Applied Chemistry for Engineering
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• v.25 no.2
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• pp.204-208
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• 2014

This study investigated the effect of hydrogen permeance and selectivity, catalyst amount, $H_2O/CO$ ratio in a feed stream, and Ar sweep gas on the performance of a water gas shift reaction in a membrane reactor. It was observed that a minimum hydrogen selectivity of 100 was needed in a membrane reactor to obtain a hydrogen yield higher than the one at equilibrium and the hydrogen yield enhancement gradually decreased as the hydrogen permeance increased. The CO conversion in a membrane reactor initially increased with the catalyst amount and reached a plateau later for a membrane reactor with a low hydrogen permeance while the high CO conversion independent of a catalyst amount was observed for a membrane reactor with a high hydrogen permeance. For the $H_2O/CO$ ratio in a feed stream higher than 1.5, a hydrogen permeance had little effect on the CO conversion in a membrane reactor and it was found that a minimum Ar molar flow rate of $6.7{\times}10^{-6}mol\;s^{-1}$ was needed to achieve the CO conversion higher than the one at equilibrium in a membrane reactor.

• 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.5
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• pp.325-335
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• 2022

In this study, zeolitic imidazolate framework-9 (ZIF-9) was synthesized and Pebax/ZIF-9 mixed membranes were prepared by varying the content in poly(ether-b-amide)-1657 (Pebax-1657), and then a single gas (N₂, CO₂) was permeated to investigate the gas permeation characteristics of the mixed membrane. As the ZIF-9 content incorporated into the pure Pebax membrane increased, the N₂ permeability gradually decreased, and the CO₂ permeability increased up to the Pebax/ZIF-9 3 wt% mixed membrane, and then decreased at the content thereafter. And among the mixed membranes, the Pebax/ZIF-9 3 wt% mixed membrane showed the highest selectivity of 69.3 by selectively accepting CO₂ as the gate-opening phenomenon occurred for the polar gas, CO₂. In addition, both the CO₂ permeability and the CO₂/N₂ selectivity increased, resulting in the closest Robeson upper-bound.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_2
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• pp.1171-1181
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• 2023

In this study, a sweep gas - vacuum hybrid type membrane degassing process was proposed for ammonia wastewater treatment. In addition, the ammonia selective recovery of the hybrid type membrane degassing process was also investigated. As a result, the hybrid type membrane degassing process showed better degassing performance (54.9 mg NH₃/m²min for 360 min) than the sweep gas type (32.3 mg NH₃/m²min) or vacuum type (22 mg NH₃/m²min). Additionally, the hybrid type membrane degassing process showed an excellent ammonia selectivity (103 times compared to Na+ Na⁺, 133 times compared to Ca²⁺). The ammonia selectivity was appeared to be due to the conversion characteristics of ammonium ion / dissolved ammonia depending on pH. The results in this study are expected to be used in the development of ammonia wastewater treatment and ammonia recovery in the future.

• Membrane Journal
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• v.25 no.1
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• pp.27-31
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• 2015

PEBAX[poly(ether-block-amide)]-NaY zeolite composite membrane was studied on the permeability of penetrant $H_2$, $N_2$, $CO_2$ and $CH_4$ and the selectivity. When the NaY zeolite contents of PEBAX-NaY zeolite membranes were increased, the permeability of $H_2$ was increased, but the permeability of $N_2$, $CH_4$ and $CO_2$ was decreased. By the addition of NaY zeolite into PEBAX, the gas selectivity for $H_2$, $N_2$ and $CO_2$ was decreased except the increase of selectivity of $H_2/N_2$. $CO_2/N_2$, $H_2/CO_2$ and Gas/$CH_4$. The highest selectivity among these gases was from $CO_2$. In particular, the gas selectivity for $CO_2$ was the greatest with a value of 12~156.

• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.387-390
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• 2004

Thick film alcohol gas sensors were fabricated. Their electrical properties and gas sensing characteristics were investigated. The sensitivity of $1wt.\%$ Pd-doped ${\gamma}-Fe_2O_3$ thick film heat treated at $400^{\circ}C$, 2hrs was $74\%$ to 500ppm alcohol gas at the operating temperature of $250^{\circ}C$. The selectivity of the film to alcohol was good. It showed fast response time to low concentrations of alcohol in air, hence this sensor can be used as a breath sensor.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.4
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• pp.407-416
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• 1988

Thick film city gas sensors were fabricated using \ulcornerFe2O3 and \ulcorner-Fe2O3 as raw materials. Their electrical properties and sensitivity characteristics were investigated and the surface conditions for various firing temperatures were analyzed. The fabricated devices exhibited high sensitivity to butane gas(75~80% n 1, 000ppm butane ambient). Also they showed good selectivity and long-term stability. A city gas alarm system using fabricated sensors was made for the practical application.

• Electrical & Electronic Materials
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• v.8 no.1
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• pp.90-94
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• 1995

Reactive Ion Etching(RIE) of Si$_{3}$N$_{4}$ in a CF$_{4}$/O$_{2}$ gas plasma exhibits such good anisotropic etching properties that it is widely employed in current VLSI technology. However, the RIE process can cause serious damage to the silicon surface under the Si$_{3}$N$_{4}$ layer. When an atmospheric pressure chemical vapor deposited(APCVD) SiO$_{2}$ layer is used as a etch-stop material for Si$_{3}$N$_{4}$, it seems inevitable to get a good etch selectivity of Si$_{3}$N$_{4}$ with respect to SiO$_{2}$. Therefore, we have undertaken thorough study of the dependence of the etch rate of Si$_{3}$N$_{4}$ plasmas on $O_{2}$ dilution, RF power, and chamber pressure. The etch selectivity of Si$_{3}$N$_{4}$ with respect to SiO$_{2}$ has been obtained its value of 2.13 at the RF power of 150 W and the pressure of 110 mTorr in CF$_{4}$ gas plasma diluted with 25% $O_{2}$ by flow rate.