• Title/Summary/Keyword: Supercritical carbon dioxide

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Enzymatic Hydrolysis of Cotton Fibers in Supercritical $CO_2$

  • Gayrat Muratov;Kim, Chul
    • Biotechnology and Bioprocess Engineering:BBE
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    • v.7 no.2
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    • pp.85-88
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    • 2002
  • A study was carried out on the application of supercritical fluid to the hydrolysis of boll fibers of cotton (cultivar Tashkent-6 of Gossypium hirsutum L.) by cellulase enzymes from Trichoderma viride, Trichoderma reesei and Aspergillus niger. Conditions of the enzymatic process were optimized. The stabilities of cellulase enzymes were sustained at the pressure of up to 160 attn for 48 hours at 5$0^{\circ}C$ in supercritical carbon dioxide.

Numerical Comparison of Thermalhydraulic Aspects of Supercritical Carbon Dioxide and Subcritical Water-Based Natural Circulation Loop

  • Sarkar, Milan Krishna Singha;Basu, Dipankar Narayan
    • Nuclear Engineering and Technology
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    • v.49 no.1
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    • pp.103-112
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    • 2017
  • Application of the supercritical condition in reactor core cooling needs to be properly justified based on the extreme level of parameters involved. Therefore, a numerical study is presented to compare the thermalhydraulic performance of supercritical and single-phase natural circulation loops under low-to-intermediate power levels. Carbon dioxide and water are selected as respective working fluids, operating under an identical set of conditions. Accordingly, a three-dimensional computational model was developed, and solved with an appropriate turbulence model and equations of state. Large asymmetry in velocity and temperature profiles was observed in a single cross section due to local buoyancy effect, which is more prominent for supercritical fluids. Mass flow rate in a supercritical loop increases with power until a maximum is reached, which subsequently corresponds to a rapid deterioration in heat transfer coefficient. That can be identified as the limit of operation for such loops to avoid a high temperature, and therefore, the use of a supercritical loop is suggested only until the appearance of such maxima. Flow-induced heat transfer deterioration can be delayed by increasing system pressure or lowering sink temperature. Bulk temperature level throughout the loop with water as working fluid is higher than supercritical carbon dioxide. This is until the heat transfer deterioration, and hence the use of a single-phase loop is prescribed beyond that limit.

Phase Equilibria Measurement of Binary Mixture for the Propoxylated Neopentyl Glycol Diacrylate in Supercritical Carbon Dioxide

  • Byun, Hun-Soo
    • Korean Chemical Engineering Research
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    • v.54 no.2
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    • pp.206-212
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    • 2016
  • Experimental data are reported on the phase equilibrium of propoxylated neopentyl glycol diacrylate in supercritical carbon dioxide. Phase equilibria data were measured in static method at a temperature of (313.2, 333.2, 353.2, 373.2 and 393.2) K and at pressures up to 27.82 MPa. At a constant pressure, the solubility of propoxylated neopentyl glycol diacrylate for the (carbon dioxide + propoxylated neopentyl glycol diacrylate) system increases as temperature increases. The (carbon dioxide + propoxylated neopentyl glycol diacrylate) system exhibits type-I phase behavior. The experimental result for the (carbon dioxide + propoxylated neopentyl glycol diacrylate) system is correlated with Peng-Robinson equation of state using mixing rule. The critical property of propoxylated neopentyl glycol diacrylate is predicted with Joback and Lyderson method.

Extraction of Active Compounds from Angelica gigas using Supercritical Carbon Dioxide and its Physiological Activity (초임계 이산화탄소를 이용한 참당귀 유효 성분의 추출 및 생리활성 효능)

  • Park, Su In;Heo, Soo Hyeon;Lee, Jinseo;Shin, Moon Sam
    • Journal of Convergence for Information Technology
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    • v.11 no.6
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    • pp.206-212
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    • 2021
  • This study aimed to maximize the efficacy of Angelica gigas by finding a more effective way to extract active compounds from Angelica gigas. After extracting Angelica gigas by hydrothermal, ethanol, and supercritical carbon dioxide extraction methods, analysis of decursin and decursinol angelate content, quantification of total polyphenol content, and evaluation of efficacy of antioxidant, whitening, and antibacterial were conducted. The content of decursin and decursinol angelate was very high at 38.65% of the supercritical carbon dioxide extract, and the total polyphenol content was high in the order of hydrothermal extract, ethanol extract and supercritical carbon dioxide extract, but the difference was relatively small. The antioxidant effects were consistent with the total polyphenol content, and the antibacterial effects were consistent with the decursin and decursinol angelate content. In other words, through this study, we found that the optimal method for extracting active compounds from Angelica gigas is the supercritical carbon dioxide extraction method.

Extraction of Indole Alkaloids from Catharanthus roseus by Using Supercritical Carbon Dioxide with Ethanol (초임계 이산화탄소와 에탄올을 이용한 일일초로부터 인들 알칼로이드의 추출에 관한 연구)

  • 송규민;박상우
    • KSBB Journal
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    • v.6 no.4
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    • pp.407-412
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    • 1991
  • The extraction of indole alkaloids from Catharanthus roseus using the supercritital carbon dioxide with ethanol was performed in various temperature and pressure conditions. The contents of vindoline in the extracts were determined by HPLC. In this study, the flow rate of cosolvent ehtanol was 20.4$\mu$l/min, about 3 wt.% of flow rate of supercritical carbon dioxide. However the effect of ethanol on the yield of extracted vindoline was not significant.

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A Study of Separation of γ-linolenic acid with Supercritical Carbon Dioxide (초임계 이산화탄소를 이용한 감마 리놀렌산의 분리에 대한 연구)

  • Cho, In-Ho;Sang, Hie-Sun
    • Journal of the Korean Society of Industry Convergence
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    • v.10 no.2
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    • pp.97-104
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    • 2007
  • In different approaches were extracted from evening primrose seed by supercritical fluids carbon dioxide and for comparison with hexane as solvent. The extracts have been analyzed qualitatively and quantitatively to evaluate yield and selectivity of ${\gamma}$-linolenic acid. The yields extracts with supercritical fluids carbon dioxide were higher than those with hexane. When this process produces commercially, will get a many economic profit.

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Changes of Quality Characteristics of Dongchimi by Supercritical Carbon Dioxide as Sterilization Method (초임계 이산화탄소를 이용한 살균방법이 동치미의 품질에 미치는 영향)

  • Hong, Joo-Heon;Park, Joo-Seok;Lee, Wong-Young
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.37 no.10
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    • pp.1330-1336
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    • 2008
  • Here we studied the changes on quality characteristics of Dongchimi by supercritical carbon dioxide to manufacture Dongchimi of high quality. There were no distinctive changes of acidity, pH, color difference, free sugar and organic acid of the Dongchimi treated with supercritical $CO_2$, compared to the control. The content of vitamin C in Dongchimi, which was treated with supercritical $CO_2$ (at 25 MPa, $35^{\circ}C$) was 0.826 mg/mL, and was similar to that of 0.1 MPa. Unpleasant volatile compounds such as dimethyl disulfide, metyl trisulfide and methyl propyl disulfide in Dongchimi were decreased by supercritical $CO_2$; also, treatment of supercritical $CO_2$ was useful to improve flavor of Dongchimi. Polygalacturonase activity was decreased 40.3% after supercritical carbon dioxide treatment at 25 MPa and $55^{\circ}C$.

Fabrication of poly(ethylene oxide)/clay nanocomposites using supercritical fluid process (초임계 공정을 이용한 폴리에틸렌옥사이드/클레이 나노복합체 제조)

  • Kim, Yong-Ryeol;Jeong, Hyeon-Taek
    • Journal of the Korean Applied Science and Technology
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    • v.31 no.1
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    • pp.143-150
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    • 2014
  • Recently, supercritical fluid process has been widely used in material synthesis and processing due to their remarkable properties such as high diffusivity, low viscosity, and low surface tension. Supercritical carbon dioxide is the most attractive solvent owing to their characteristics including non-toxic, non-flammable, chemically inert, and also it has moderate critical temperature and critical pressure. In addition, supercritical carbon dioxide would dissolve many small organic molecules and most polymers. In this study, we have prepared the poly (ethylene oxide)/clay nanocomposites using supercritical fluid as a carbon dioxide. Commercialized Cloisites-15A and Cloisites-30B used in this study, which are modified with quaternary ammonium salts. The nanocomposites of polymer/clay were characterized by XRD, TGA and DSC. Poly (ethylene oxide)/clay nanocomposites by supercritical fluid show higher thermal stability than nanocomposites prepared by melt process. In addition, supercritical fluid process would be increased dispersibility of the nanoclay in the matrix.

Total Polyphenol Content and Antioxidative Activities of Mistletoe(Viscum album) Extracts by Supercritical Carbon Dioxide (초임계 이산화탄소를 이용한 겨우살이(Mistletoe, Viscum album) 추출물의 폴리페놀 함량 및 항산화 활성)

  • Jang, Tae-Oh;Yoo, Yang-Hoon;Hwang, Yong-Chul;Kim, Hyun-Ku;Woo, Hyun-Chul
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.39 no.1
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    • pp.20-24
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    • 2010
  • This study was performed to investigate antioxidant activities of Mistletoe (MS) extracts by measuring electron donating ability (EDA), super oxide dismutase (SOD)-like activity and total polyphenol content (TPC). The extracts were obtained using supercritical carbon dioxide, hot-water and ethanol extraction. EDAs was the higher in ethanol extract (70.53%) than water (36.73%) or supercritical carbon dioxide extract (15.73% at 400 bar, $30^{\circ}C$) at concentration of 10 mg/mL. However, SOD-like activities and TPCs were the highest in the supercritical carbon dioxide extract. At concentration of 1 mg/mL, supercritical carbon dioxide extract (22.54% at 200 bar, $40^{\circ}C$) was higher SOD activity than water (7.85%) and ethanol extract (6.12%). Regarding TPCs of MS extracts, the content was the highest in supercritical carbon dioxide extract (17.57 wt% catechin equivalent at 200 bar, $50^{\circ}C$) followed by ethanol and water extract. These results suggest that it can be useful to develop functional foods using antioxidative active compounds of MS with high polyphenol contents.

FEED Framework Development for Designing Supercritical Carbon Dioxide Power Generation System (초임계 이산화탄소 발전시스템 설계를 위한 FEED(Front End Engineering Design) 프레임워크 개발)

  • Kim, Joon-Young;Cha, Jae-Min;Park, Sungho;Yeom, Choongsub
    • Journal of the Korean Society of Systems Engineering
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    • v.13 no.2
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    • pp.65-74
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    • 2017
  • Supercritical carbon dioxide power system is the next generation electricity technology expected to be highly developed. The power system can improve net efficiency, simplify cycle configuration, and downsize equipment compared to conventional steam power system. In order to dominate the new market in advance, it is required to found Front End Engineering Design (FEED) Framework of the system. Therefore, this study developed the FEED framework including design processes for the supercritical carbon dioxide power system, information elements for each process, and relationships for each element. The developed FEED framework is expected to be able to secure systematic technological capabilities by establishing a common understanding and perspective among multi-field engineers participating in the design.