• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.148.2-148.2
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• 2013

We prepared hydrophobic PDMS-coated porous silica as pre-concentration adsorbent for chemical warfare agents (CWAs). Since CWAs can be harmful to human even with a small amount, detecting low-concentration CWAs has been attracting attention in defense development. Porous silica is one of the promising candidates for CWAs pre-concentration adsorbent since it is thermally stable and its surface area is sufficiently high. A drawback of silica is that adsorption of CWAs can be significantly reduced due to competitive adsorption with water molecule in air since silica is quite hydrophilic. In order to solve this problem, hydrophobic polydimethylsiloxane (PDMS) thin film was deposited on silica. Adsorption and desorption of chemical warfare agent (CWA) simulants (Dimethylmethylphosphonate, DMMP and Dipropylene Glycol Methyl Ether, DPGEM) on bare and PDMS-coated silica were studied using temperature programed desorption (TPD) with and without co-exposing of water vapor. Without exposure of water vapor, desorbed amount of DMMP from PDMS-coated silica was twice larger than that from bare silica. When the samples were exposed to DMMP and water vapor at the same time, no DMMP was desorbed from bare silica due to competitive adsorption with water. On the other hand, desorbed DMMP was detected from PDMS-coated silica with reduced amount compared to that from the sample without water vapor exposure. Adsorption and desorption of DPGME with and without water vapor exposing was also investigated. In case of bare silica, all the adsorbed DPGME was decomposed during the heating process whereas molecular DPGME was observed on PDMS-coated silica. In summary, we showed that hydrophobic PDMS-coating can enhance the adsorption selectivity toward DMMP under humid condition and PDMS-coating also can have positive effect on molecular desorption of DPGME. Therefore we propose PDMS-coated silica could be an adequate adsorbent for CWAs pre-concentration under practical condition.

• Journal of Biosystems Engineering
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• 제30권2호
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• pp.95-101
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• 2005

Adsorption and desorption experiments were carried out on rough rice and brown rice (Nampyung) at 5, 15, 25, 35, $45^{\circ}C$ for moisture contents between 8.7 and $25\%$ (db). The method employed was to measure the equilibrium relative humidity (ERH) of air in contact with the grain under static conditions, using an electronic hygrometer The effects of temperature and moisture contents were investigated, and the measured values were fitted to the modified Henderson, the modified Chung-Pfost, the modified Halsey and the modified Oswin model. The ERHs of rough rice and brown rice decreased with an decrease in moisture content and temperature, and the effects of temperature was no significant at moisture content of $25\%$ (db). Equilibrium moisture content (EMC) of brown rice was higher than rough rice at same temperature and relative humidity. Desorption EMC is higher than the adsorption, but there is no significant difference between desorption and adsorption EMC in moisture content near $25\%$ (db) at rough rice and near 9, 21 and $25\%$ (db) at brown rice. The modified Oswin model was the best in describing the adsorption EMC and the modified Chung-Pfost model was the best in describing the adsorption ERH of rough rice. The modified Oswin model was the best in describing the adsorption EMC/ERH of brown rice. The modified Chung-Pfost model was the best in describing the desorption EMC/ERH of rough rice and brown rice.

• 한국지하수토양환경학회지:지하수토양환경
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• 제28권6호
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• pp.58-70
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• 2023

The improper management of radioactive waste or accidents caused by natural disasters can result in the release of radioactive materials into the surrounding environment, potentially leading to soil and groundwater contamination by radionuclides. In this study, adsorption-desorption behaviors of the radionuclides (cobalt and strontium) in natural soil, montmorillonite, Mn-PILC, Fe-PILC, and fishbone were investigated. Several models were used to predict adsorption isotherms of radionuclides on various absorbents. Adsorption isotherms of cobalt and strontium in several adsorbents were examined at pH 5.5. The amount of sorbed cobalt and strontium were represented fishbone > natural soil > Mn-PILC > Fe-PILC > montmorillonite and natural soil > Mn-PILC > fishbone > Fe-PILC > montmorillonite, respectively. Adsorption datas were fitted with several models such as Freundlich, Langmuir, Sips, Redlich-Peterson, Khan, and Generalized model. The results of curve fitting showed R²> 0.98 in all of adsorption models, except Sr²⁺ adsorption onto montmorillonite. For modified clays (Mn-PILC, Fe-PILC), it is suggested that, unlike natural soils and fish bones, there are not only single adsorption mechanisms but also adsorption mechanisms based on chemical adsorption and surface charge. In the case of fish bones, due to the relatively higher adsorption capacity than modified clays and its characteristic of significant desorption, it is expected more suitable for the removal of radionuclides in aquatic environments than for the immobilization of radionuclides in soil.

• 한국광물학회지
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• 제22권4호
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• pp.289-295
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• 2009

카올리나이트 KGa-1b (표준 점토)의 인산염 탈착 특성을 규명하기 위하여 벳치(batch) 흡착-탈착 실험을 실시하였으며, 탈착 과정은 연속추출법에 따라 pH 4에서 시행하였다. 인의 함량은 UV 분광분석기를 시용하여 측정하였으며, 이 때 파장은 820 nm를 이용하였다. 카올리나이트의 인산염 흡착-탈착 반응은 비가역적으로 일어나며, 흡착된 대부분의 인산염은 고착되는 경향을 나타낸다. 인산염 탈착 등온선은 반응 시간이 짧은 경우 프로인드리히 등온선에, 반응 시간이 긴 경우 탬킨 등온선에 더 일치하는 경향을 보인다. 인산염 탈착 반응은 초기의 빠른 반응과, 후기의 느린 반응으로 구분된다. 흡착된 인산염의 농도가 높아질수록 탈착률은 감소하는 경향을 보이며, 탈착 시간이 길어지면 탈착률은 감소하는 경향을 보여준다.

• BMB Reports
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• 제30권5호
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• pp.346-351
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• 1997

The maximum adsorption/desorption conditions and the adsorption mechanism of globular proteins to vaccine adjuvants were determined. The maximum adsorption ratio of protein to the $Al^{3+}$ content of aluminum oxyhydroxide and the optimal adsorption pH are 2:1 (${\mu}g:{\mu}g$) for bovine serum albumin (BSA) at pH 6.0 and 2.5:1 (${\mu}g:{\mu}g$) for immunoglobulin G (IgG) at pH 7.0, respectively. The maximum adsorption ratio onto aluminum phosphate gel was 1.5:1 (${\mu}g$ Protein:${\mu}g$ $Al^{3+}$) at pH 5.0 for both BSA and IgG. Adsorption of the native globular proteins, BSA and IgG, to aluminum oxyhydroxide and aluminum phosphate gel was reversible as a function of pH. Complete desorption of these proteins from aluminum phosphate gel was observed at alkaline pH, whereas only 80~90% removal from aluminum oxyhydroxide was achieved with alkaline pH and 50 mM phosphate buffer. We conclude that electrostatic and hydrogen bonding interactions between the native proteins and adjuvants are important binding mechanisms for adsorption, and that the surface charge of the protein and the colloid components control the maximum adsorption conditions.

• Elastomers and Composites
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• 제50권1호
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• pp.55-61
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• 2015

Manufacturing process of OLED contains adsorption-desorption process of glass substrate. There are several adsorption methods of glass substrate such as atmospheric pressure, vacuum and electrostatic adsorption. However, these methods are very complex to connect system. Therefore, the adsorption method using silicone rubber based sticking chuck was proposed in this study. Three types of silicone rubbers having 0, 19.3 and 32.2 wt% of fluorine were used and their mechanical properties, surface energies and adsorption properties were examined. According to the results ${\sigma}_{300}$ and hardness increased with increasing fluorine contents, but elongation was decreased. Also, fluorosilicone rubber containing 32.2 wt% of fluorine showed the lowest surface tension, among three types of rubber and resulted in the highest initial tack with glass substrate. After the adsorption-desorption test of 300,000 cycles was performed, the adsorption force of S-1 (silicone rubber) decreased largely from 2.34 to 0.73 MPa. However, the S-3 (fluorosilicone rubber having 32.2 wt%. of fluorine) decreased only from 3.15 to 2.24 MPa. From this study, we obtained the valuable equations related to long term durability of silicone based sticking chuck. Finally the transfer of silicone rubber to glass substrate with the adsorption-desorption process was not occurred and this phenomenon was examined by UV-Visible spectroscopy.

• 한국대기환경학회지
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• 제25권2호
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• pp.122-132
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• 2009

Adsorption of toluene by activated carbon fiber (ACF) coated with dielectric heating element and desorption by applying microwave were investigated. In order to prepare adsorbent so that VOC can be desorbed by microwave heating, fine dielectric heating element with nano size was coated on the surface of the ACF using hybrid binder. Eight adsorbents (ACF-DHE, Activated Carbon Fiber coated with Dielectric Heating Element) were prepared with different amount of dielectric heating element, kinds of hybrid binder, and solvent. In order to investigate adsorption characteristics, BET surface area, pore volume, and average pore size were measured for each adsorbent including ACF. Breakthrough experiments with toluene concentration, flow rate, bed length using fixed bed reactor were performed to investigate adsorbality of adsorbent, and results were compared with that of the ACF. Desorption reactor was constructed with modified microwave oven to investigate heating effect on ACF-DHE by applying microwave power. Each adsorbent saturated with toluene were put into desorption reactor. Composition of desorbed gas generated by applying controlled microwave power to reactor was measured. Up to now, hot air desorption method has been used. Experimental results showed that desorption method with new adsorbent prepared by coating dielectric heating element on ACF can be used for industrial application.

• Journal of Industrial and Engineering Chemistry
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• 제67권
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• pp.312-315
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• 2018

Although the reversibility of 10,12-pentacosadiynoic amino meta-acid(PCDA-mBzA) against temperature and pH was reported, the modulation of reversibility by ion adsorption at terminal functional group has not been investigated. In this work, we developed a simple method for modulating the reversibility of PCDA-mBzA films upon a thermal stimulus by cadmium ion adsorption inducing the breakage of the outer hydrogen bonding of two hydrogen bonds, which are responsible for the reversible properties of PCDA-mBzA. External reflection-Fourier transform infrared (ER-FTIR) analyses revealed that the hydrogen bonding between the carboxylic acid groups was broken through ion adsorption and only a single hydrogen bond between the amide groups remained in the PCDA-mBzA polymer. In addition, PCDA-mBzA films could recover their original property through cadmium ion desorption. These results present that the transition between reversibility and irreversibility can be modulated artificially simply through the adsorption and desorption of metal ions.

• 한국세라믹학회지
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• 제45권12호
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• pp.832-838
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• 2008

Diatomite, bentonite and zeolite were used as porous materials for fabricating hygroscopic panels. Moisture adsorption and desorption of porous materials were investigated and hydrothermal method was applied to fabricate panels. Cheolwon diatomite and Pohang zeolite showed excellent characteristics of moisture adsorption and desorption. These characteristics were caused by higher surface area and pore volume of porous materials. Correlation coefficient between surface area and moisture adsorption content of porous materials was 0.93. Moisture adsorption contents were influenced by surface area and pore volume of panels, and surface area more effected on moisture adsorption. Correlation coefficient between surface area and moisture adsorption content of panels was 0.86. Moisture adsorption content of panel with 10% Pohang zeolite was $180\;g/m^2$ and that of 10% Cheolwon diatomite was $170\;g/m^2$. Moisture desorption content of panel with 10% Pohang zeolite was $105\;g/m^2$. Moisture adsorption contents of panel with porous materials were higher than that of panel without porous materials.

• Korean Chemical Engineering Research
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• 제43권3호
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• pp.432-437
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• 2005

혼합가스로부터 $CO_2$를 분리, 회수하기 위하여 활성탄소섬유를 흡착제로 사용한 전기변동흡착(electric swing adsorption, ESA) 공정의 타당성을 검토하였다. 활성탄소 섬유는 상압에서도 $CO_2$에 대해 빠른 흡착 속도를 보였으며, 비교적 짧은 흡착대와 긴 파과시간, 흡착제의 단위무게당 높은 흡착량을 나타내었다. 포화흡착된 흡착탑의 재생에서 비표면적이 큰 활성탄소섬유일수록 일정한 모양의 파과곡선을 유지하여 흡착-탈착의 재생사이클에 유리하였다. 진공탈착에 의한 흡착탑의 재생률은 64 cmHg의 압력에서도 64％ 이상이었고, 전기탈착을 병행한 hybrid 재생단계에서는 17％의 추가적인 재생률을 보이며 7-8 Wh의 낮은 재생에너지에서도 높은 재생률을 보였다.