• Korean Chemical Engineering Research
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• 제47권3호
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• pp.355-361
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• 2009

선택적 고체순환을 위한 2탑 유동층 공정에서 고체분리기에 의한 고체분리속도에 미치는 조업변수들의 영향을 측정 및 고찰하였다. 본 연구에서 개발한 고체분리기를 이용하여 굵은입자(212~300 또는 $425{\sim}600{\mu}m$)와 고운입자($63{\sim}106{\mu}m$)의 분리가 가능하였으며 고체분리속도는 66~987 g/min의 범위를 나타내었다. 고체분리속도는 고체분사노즐의 유속, 고체층 높이, 고체분사노즐의 직경, 고운입자와 굵은입자의 입자크기 차이, 고체분리기 금속망 간극크기 및 혼합입자 중 고운입자의 무게분율이 증가함에 따라 증가하였으며 유동화 속도의 영향은 크지 않았다.

• 한국재료학회지
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• 제28권7호
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• pp.417-422
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• 2018

The stereotype of flexible MOFs(Amino-MIL-53) and carbonized porous carbon prepared from renewable resources is successfully synthesized for $CO_2$ reduction application. The textural properties of these microporous materials are investigated, and their $CO_2$ storage capacity and separation performance are evaluated. Owing to the combined effects of $CO_2-Amino$ interaction and its flexibility, a $CO_2$ uptake of $2.5mmol\;g^{-1}$ is observed in Amino-MIL-53 at 20 bar 298 K. In contrast, $CH_4$ uptake in Amino-MIL-53 is very low up to 20 bar, implying potential sorbent for $CO_2/CH_4$ separation. Carbonized samples contain a small quantity of metal residues(K, Ca, Mg, S), resulting in naturally doped porous carbon. Due to the trace metal, even higher $CO_2$ uptake of $4.7mmol\;g^{-1}$ is also observed at 20 bar 298 K. Furthermore, the $CH_4$ storage capacity is $2.9mmol\;g^{-1}$ at 298 K and 20 bar. To evaluate the $CO_2$ separation performance, the selectivity based on ideal adsorption solution theory for $CO_2/CH_4$ binary mixtures on the presented porous materials is investigated.

• 멤브레인
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• 제32권1호
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• pp.13-22
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• 2022

세계적인 에너지 수요의 증가는 통제할 수 없는 환경 오염을 야기하고 있다. 화석 연료에 대한 수요와 그로 인한 탄소 배출이 지구 온난화와 기후 변화로 이어진 것이다. 핵에너지는 청정 에너지를 생산하는 대체 자원이지만 핵연료 채굴은 유해한 화학물질과 관련이 있다. 반면에 막 분리 과정을 통해 바닷물에서 중요 광물을 채굴하는 것은 효율적이며 친환경적이다. 분리와 흡착을 통해 해수로부터 주요 광물을 채굴하는 것은 또 다른 효율적인 과정이다. 희토류 원소에서 악티늄족을 회수하는 것은 매우 어렵고 고비용의 과정이다. 압력 기반 막 분리 과정은 친환경적일 뿐만 아니라 경제적으로 실현가능한 과정이기도 하다. 본 리뷰에서 다루는 막 공정에는 폴리에테르 설폰, 폴리아미드, 폴리이미드, 폴리아미독신 및 하이브리드 막이 있다. 또한 흡착 공정의 경우, 주로 아미독심 종류의 흡착제가 논의될 것이다.

• 분석과학
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• 제37권2호
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• pp.123-129
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• 2024

We present a rapid method for the determination of Cs, Sr, and Ba, heat generators found in highly active liquid wastes, by gas-pressurized extraction chromatography (GPEC) using a column containing a cation-exchange resin. GPEC is a microscale column chromatographic technique that uses a constant flow rate of solvent (0.07 mL/min) with pressurized nitrogen gas supplied through a valve. In particular, because this method uses a small sample volume (a few hundred microliters), it produces less chemical waste and allows for faster separation compared to traditional column chromatography. In this study, we evaluated the separation of Cs, Sr, and Ba using GPEC. The eluate from the column (GPEC or conventional column chromatography) was quantitatively analyzed using inductively coupled plasma-mass spectrometry to measure the column recovery and precision. The column reproducibility of the proposed GPEC system (RSDs of recoveries) ranged from 2.7 to 4.1 %, and the column recoveries for the three elements ranged from 72 to 98% when aqueous HCl was used as the eluent. The GPEC results are slightly different in efficiency and separation resolution compared to those of conventional column chromatography because of the differences in the eluent flow rate as well as the internal diameter and length of the column. However, the two methods had similar recoveries for Cs and Sr, and the precision of GPEC was improved by two-fold. Remarkably, the solvent volume required for GPEC analysis was five times lower than that of the conventional method, and the total analysis time was 11 times shorter.

• 에너지공학
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• 제13권1호
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• pp.34-39
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• 2004

본 논문에서는 압축공기를 작동매체로 한 저압용 보텍스튜브에 대한 에너지 분리과정을 상세히 연구하였다 먼저 보텍스튜브에서 에너지 분리되어 나오는 온공기와 냉공기의 온도변화에 대하여 실험하였고, 보텍스튜브의 안쪽표면의 최대벽면온도 변화와 보텍스튜브 내의 온도분포를 통하여 보텍스튜브 내 유동장에서의 정체점의 위치에 대한 유용한 정보를 얻게 되었다. 이를 바탕으로 보텍스튜브의 노즐면적비와, 오리피스의 크기에 따른 에너지분리 과정 등을 실험을 통하여 알아보았다. 이러한 기하학적 형상의 변화실험을 통하여 저압용？대형 보텍스튜브의 에너지 분리과정이 고압형\ulcorner소형 보텍스튜브 보다 에너지 분리효과가 증대됨으로 인하여 최적의 노즐면적비와 오리피스지름비가 차이가 있음을 알 수 있었다.

• 한국재료학회지
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• 제9권4호
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• pp.341-344
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• 1999

We reported compositional separation(CS) into Co-enriched and Cri-enriched components inside the grains of Co-Cr based thin films prepared by rf sputtering. CS strongly depends on the sputtering conditions of substrate temperature and target composition. Tuning the microstructure of the Co-Cr films is important in order to employ the CS for high-density magnetic recording. We investigated the origin of CS from thermodynamic viewpoint. We employ a spinodal decomposition-like model to describe the origin of the CS in Co-Cr films. We consider the total free energy of the Co-Cr films as the sum of several free energies of; 1) thermodynamic mixing entropy of a binary solid solution, 2) magnetic ordering interaction(MOI) energy below the Curie temperature, and 3) excess interaction energy(XS) caused by the sputtering process as a function of temperature and composition. Those energies distorted the total free energy like the spinodal decomposition and caused the compositionally separated fine microstructure inside the grains. If the second derivative of the total free energy with respect to Cr composition becomes negative at a given substrate temperature, we may observe a metastable compositional separation inside the Co-Cr alloy films. We expect to exploit the microstructure of CS for ultra-high density magnetic recording.

• 방사선산업학회지
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• 제5권2호
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• pp.101-106
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• 2011

The separation of germanium and gallium ion with metal oxide was introduced into the development of $^{68}Ge/^{68}Ga$ generator. Germanium and gallium within mixed solution were respectively separated by using a liquid-liquid extraction and a column chromatographic method. The separation of Ge within high concentrated hydrochloric and sulfuric acid was conducted by the extraction to $CCl_4$ and the back-extraction to 0.05 M HCl. An optimum condition of the extraction by $CCl_4$ was in 5~7 M HCl and efficiency was around 80%. The gallium was selectively separated by using $Al_2O_3$ among metal oxides as sorbents from the mixed solution in 0.04~0.10 M HCl condition.

• 한국재료학회지
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• 제30권12호
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• pp.655-659
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• 2020

Hydrogen isotopes (i.e. deuterium and tritium) are supplied to the tokamak in the International Thermonuclear Experimental Reactor (ITER) fuel cycle. One important part of the ITER fuel cycle is the recycling of unused fuel back to the tokamak, as almost 99 % of fuel is unburned during fusion reaction. For this, cryogenic distillation has been used in the isotope separation system (ISS) of ITER, but this technique tends to be energy-intensive and to have low selectivity (typically below 1.5 at 24 K). Recently, efficient isotope separation by porous materials has been reported in the so-called quantum sieving process. Hence, in this study, hydrogen isotope adsorption behavior is studied using chemically stable ZIF-11. At low temperature (40 K ~ 70 K), the adsorption increases and the sorption hysteresis becomes stronger as the temperature increases to 70K. Molar ratio of deuterium to hydrogen based on the isotherms shows the highest (max. 14) ratio at 50 K, confirming the possibility of use as a potential isotope separation material.

• Nuclear Engineering and Technology
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• 제54권8호
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• pp.3017-3026
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• 2022

The ¹³¹Cs radioisotope with a short half-life time and high average radiation energy can treat the cancer effectively in prostate brachytherapy. The typical ¹³¹Cs production processes have a separation step of the cesium from ¹³¹Ba to obtain a high specific radioactivity. Herein, we suggested a novel ¹³¹Cs separation method based on the Ba²⁺ adsorption of alginate beads. It is necessary to reduce the affinity of alginate beads to cesium ions for a high production yield. The carboxyl group of the alginate beads was replaced by a sulfonate group to reduce the cesium affinity while reinforcing their affinity to barium ions. The modified beads exhibited superior Ba²⁺ adsorption performances to native beads. In the fixed-bed column tests, the saturation time and adsorption capacity could be estimated with the Yoon-Nelson model in various injection flow rates and initial concentrations. In terms of the Cs elution, the modified alginate showed better performance (i.e., an elution over 88%) than the native alginate (i.e., an elution below 10%), indicating that the functional group modification was effective in reducing the affinity to cesium ions. Therefore, the separation of cesium from the barium using the modified alginate is expected to be an additional option to produce ¹³¹Cs.

• 분석과학
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• 제14권1호
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• pp.28-33
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• 2001

자연수에 존재할 가능성이 있는 $Pu^{3+}$, $Pu^{4+}$, $PuO_2{^+}$, $PuO_2{^{2+}}$ 상태의 플루토늄을 이온크로마토그래피로 분리하는 방법을 연구하였다. 각각 $SiO^-$, SiO-$SO_3{^-}$작용기를 가진 이온교환체를 충전한 두 컬럼을 이용하는 방법과, Dionex사 AG11컬럼에 oxalate/$HNO_3$ 용리액을 사용하여 IC로 분리하는 두 가지 방법을 시도하였다. 예비실험으로서 플루토늄과 화학적 성질이 유사하며 산화수가 안정한 $Eu^{3+}$, $Th^{4+}$, $NpO_2{^+}$, $UO_2{^{2+}}$을 사용하여 분리조건을 얻었다. 이 분리조건을 플루토늄에 적용시켰을 때, $SiO^-$, SiO-$SO_3{^-}$ 이온교환체를 이용한 방법은 산화수별 플루토늄을 성공적으로 분리할 수 있었다. 그러나 IC를 사용한 방법은 oxalate 용액에서 $Pu^{3+}$가 쉽게 $Pu^{4+}$로 산화되며, $PuO_2{^{2+}}$도 $PuO_2{^+}$로 환원되어 분리가 곤란하였다.