• 한국환경과학회지
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• 제12권1호
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• pp.81-86
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• 2003

The study was carried out to evaluate the new analytical method of phthalate esters(diethylphthalate, di-n-butylphthalate, butylbenzylphthalate, bis(2-ethylhexyl)phthalate), one of the endocrine disruptors, which were performed by GC/MS-SIM(selected ion monitoring). The phthalate esters were extracted from water samples using solid-phase extraction on $C_{18}$ columns. It investigated that the extraction recovery rate of phthalate esters with different solvents and solvent volume. The optimal solvent was dichloromethane and proper volume of dichloromethane for recovery of phthalate esters was 4 mL. There were good linearities(above $R^2$=0.9975) in the range 0.01~0.50mg/L, and the detection limits were below 0.01~0.03$\mu\textrm{g}$/L. The recovery rates, RSD and MDLs for phthalate esters were 80~114%, 5.0~8.1% and 0.03~0.11$\mu\textrm{g}$/L, respectively. This method shows a good precision of phthalate esters.

• Nuclear Engineering and Technology
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• 제53권10호
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• pp.3229-3235
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• 2021

The key process used in nuclear industries for the management of radiotoxicity associated with spent fuel in a closed fuel cycle is solvent extraction. An understanding of hydrodynamics and mass transfer is of primary importance for the design of mass transfer equipment used in solvent extraction processes. Understanding the interfacial phenomenon and the associated hydrodynamics of the liquid drops is essential for model-based design of mass transfer devices. In this work, the phenomenon of drop formation at the tip of a nozzle submerged in quiescent immiscible liquid phase is revisited. Previously reported force balance based models and empirical correlations are analyzed. Experiments are carried out to capture the process of drop formation using high-speed imaging technique. The images are digitally processed to measure the average drop diameter. A correlation based on the force balance model is proposed to estimate drop diameter and jet length. The average drop diameter obtained from the proposed model is in good agreement with experimental data with an average error of 6.3%. The developed model is applicable in both the necking as well as jetting regime and is validated for liquid-liquid systems having low, moderate and high interfacial tension.

• Journal of the Korean Wood Science and Technology
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• 제42권2호
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• pp.172-182
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• 2014

Extraction is a necessary element in the bioconversion of lignocellulosics to fuels and chemicals. Although various forms of chemical pretreatment of cellulosic materials have been proposed, their effectiveness varies depending on the treatment conditions and substrate. In this study, mixed hardwood (MH) and loblolly pine (LP) were pretreated with dilute acid in a 100 mL accelerated solvent extraction (ASE) at the predetermined optimal conditions: temperature: $170^{\circ}C$, acid concentration: 0.5% (w/v), and reaction time: 2~64 min. This method was highly effective for extracting the hemicellulose fraction. Total xmg (defined as the sum of xylose, mannose, and galactose) can be extracted from milled MH and LP through pressurized dilute acid treatment in maximum yields of 12.6 g/L and 15.3 g/L, respectively, representing 60.5% and 70.4% of the maximum possible yields, respectively. The crystallinity index increased upon pretreatment, reflecting the removal of the amorphous portion of biomass. The crystalline structure of the cellulose in the biomass, however, was not changed by the ASE extraction process.

• 한국물환경학회지
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• 제36권1호
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• pp.48-54
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• 2020

This paper presents a screening protocol for the selection of solvents available for the solvent extraction desalination process. The desalination solvents hypothetically and theoretically require the capability of (1) Forming hydrogen bonds with water, (2) Absorbing some water molecules into its non-polar solvent layer, (3) Changing solubility for water-solvent separation, and (4) Rejecting salt ions during absorption. Similar to carboxylic acids, amine solvents are solvent chemicals applicable for desalination. The key parameter for selecting the potential solvent was the octanol-water partitioning coefficient (Kow) of which preferable value for desalination was in the range of 1-3. Six of the 30 amine solvents can absorb water and have a variable, i.e., temperature swing solubility with water molecule for water-solvent separation. Also, the hydrogen bonding interaction between solvent and water must be stronger than the ion-dipole interaction between water and salt, which means that the salt ions must be broken from the water and only water molecules absorbed for the desalination. In the final step, three solvents were selected as desalination solvents to remove salt ions and recover water. The water recovery of these three solvents were 15.4 %, 2.8 %, 10.5 %, and salt rejection were 76 %, 98 %, 95 %, respectively. This study suggests a new screening protocol comprising the theoretical and experimental approaches for the selection of solvents for the desalination method which is a new and challenges the desalination process in the future.

• 생태와환경
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• 제41권4호
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• pp.485-489
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• 2008

Algal chlorophyll-$\alpha$ is commonly determined by spectro-photometric method using 90% acetone as solvents. However, acetone has low extraction efficiency without grinding filters, and DMF (dimethyl formamide) was tested for the compatibility with acetone. Chlorophyll-$\alpha$ concentration was determined for samples from 5 reservoirs of different trophic states and phytoplankton composition, using acetone extraction with grinding and DMF without grinding. Chlorophyll-$\alpha$ measured by DMF and Acetone did not show a significant difference when using trichromatic method of UNESCO and Lorenzen, and therefore, DMF can substitute acetone. But when acidification method was applied, they showed significant difference of 8%. It can be concluded that DMF can extract chlorophylls more effectively without grinding and it can be a better alternative for the standard extraction solvent.

• 공업화학
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• 제26권6호
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• pp.631-639
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• 2015

용매추출에 의한 코발트 분리 기술에 대해 리뷰하였고 특히 다양한 시약을 사용한 코발트의 분리 및 상용 추출용제를 사용하여 스크랩으로부터의 코발트 회수기술에 대하여 분석하였다. 코발트 분리 능력은 phosphinic > phosphonic > phosphoric acid 순으로 정리되며, 이것은 유기상내에 추출용제와 존재하는 코발트의 사면체 배위 화합물의 안정성이 증가하기 때문이다. 용매의 조성에 따라 달라지지만 주로 Cyanex 272, D2EPHA 및 PC 88A와 같은 상용 추출용제 등이 상용 추출 공정에서 우선적으로 사용되어야 하며, 다양한 조합을 효과적으로 관리한다면 코발트 함유 스크랩과 관련한 다양한 분리기술 문제점들을 해결할 수 있을 것이다.

• 자원리싸이클링
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• 제27권3호
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• pp.93-99
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• 2018

본 연구에서는 디스플레이 산업의 백금 폐스크랩을 용해, 용매추출을 통하여 백금족 성분을 효율적으로 추출하고, 추출된 백금용액을 디젤자동차 배가스 정화촉매용 전구체 용액으로서 제조하고, 그 촉매활성을 실험하였다. 용액화학적 이론 연구를 통하여 백금 화학종의 수용액상 거동을 조사하였고, 화학종들의 존재영역 및 거동을 근거로 추출 및 분리 가능방안을 수립하였다. 전기화학적 방법에 의해 폐스크랩을 용해시킴으로써, 용해시간 단축 및 추출효율을 높였으며, 로듐 성분을 분리 제거, TBP에 의한 용매추출, 염산에 의한 탈거 공정을 거쳐 Pt-Chloride-$H_2O$ 계 백금용액을 용액을 제조하고, 이 용액을 원료로 액상 아민화 반응을 통해 아민산 백금용액을 제조한 다음, 카본블랙의 연소반응에 대한 촉매 활성을 실험함으로써, 백금족 폐스크랩으로부터 고부가 백금족 화합물의 제조가능성을 연구하였다.

• 대한화학회지
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• 제22권5호
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• pp.320-325
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• 1978

우라늄의 수용액 및 산성용액으로부터 추출제 DEPA 및 DPPA로 우라늄을 추출할 때의 메카니즘을 밝히기 위하여 추출 중에 형성되는 우라늄 착물을 분리, 유리한 후 적외선 스펙트럼, 핵자기공명 스펙트럼, 화확분석 및 분자량 측정결과 등을 이용하여 규명하였다. 우라늄은 추출과정에서 유기인산 에스테르인 추출제 DEPA 및 DPPA의 산성 수소와 이온 교환에의하여 킬레이트형의 우라늄 착물을 형성하며 DEPA의 경우 분자량이 약 $2.1{\times}10^4$인 고분자물질임을 알았다. 또한 이러한 유리된 우라늄의 착물은 추출중에 형성되는 착물과 동일함을 밝혔으며 추출제 DEPA의 경우 우라늄의 추출 분배계수는 수용액의 경우 제일 크고 산성 수용액인 경우 $H_3PO_4의 순으로 증가함을 알았다.

• 자원리싸이클링
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• 제29권6호
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• pp.79-87
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• 2020

염산의 용매추출 및 탈거 거동을 조사하기 위해 상용화추출제인 LIX 63 단독 및 TEHA/ Cyanex 923/ Aliquat 336의 혼합추출제와 ALi-SCN과 ALi-PC 이온성액체를 사용하였다. 상기 추출제중에서 ALi-PC가 가장 높은 추출률(80%)을 보였으나 탈거가 어려웠다. 반면 LIX 63의 경우 추출률은 낮았으나, 탈거율은 81%로 가장 높았다. 옥탄올을 유기상에 첨가하면 염산 추출이 오히려 감소했다. 에탄올을 염산용액에 첨가하면 LIX 63, ALi-PC, ALi-SCN에 의한 염산의 추출과 탈거 거동이 크게 개선되었다.

• 생약학회지
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• 제53권4호
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• pp.202-206
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• 2022

Salidroside is a major phenolic glycoside of Acer tegmentosum (Aceraceae) and known to be a hepatoprotective compound. Extraction conditions are one of the most important factors to save time and cost from an economic point of view. For this reason, this study was conducted to optimize the extraction condition for maximum yield of salidroside. For optimization, three extraction factors such as ethanol concentration (%), extraction temperature (℃), and solvent to material ratio (mg/mL) were tested and optimized for maximum yield of salidroside using response surface methodology (RSM). The optimal condition was obtained as an ethanol concentration of 53.4%, an extraction temperature at 67.11℃ and a solvent to material ratio (mg/mL), 195.55 mg/ml. The salidroside yield under optimal conditions was found to be 1.59 mg/g dried samples, which were well-matched with the predicted value of 1.56 mg/g dried samples. These results will provide useful information about optimized extraction conditions for the development of salidroside as hepatoprotective therapeutics.