• Title/Summary/Keyword: subcritical water extraction

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Extraction of PCBs by Subcritical Water Extraction (Subcritical Water Extraction에 의한 PCBs 추출)

  • Kwak, Dong Hwan;Moon, Ji Yong;Lee, Sung In;Jeong, Gi Ho
    • Analytical Science and Technology
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    • v.13 no.4
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    • pp.511-519
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    • 2000
  • Water in the supercritical state ($T{\geq}374^{\circ}C$, $p{\geq}221$ atm) is a good solvent for nonorganic pollutants, but it is extremely corrosive. Subcritical Water Extraction (SWE) is a very fast and an efficient method to extract nonpolar environmental pollutants adsorbed on the sediments and soils. Many nonpolar organic compounds are sufficiently soluble to be extracted to the water under subcritical conditions. Complete extraction of PCBs from the sediments and soils takes only a few minutes by applying SWE with the subcritical water at 50 atm and at $260^{\circ}C$.

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In vitro cytotoxic activity of ginseng leaf/stem extracts obtained by subcritical water extraction

  • Lee, Kyoung Ah;Kim, Kee-Tae;Chang, Pahn-Shik;Paik, Hyun-Dong
    • Journal of Ginseng Research
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    • v.38 no.4
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    • pp.289-292
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    • 2014
  • Ginseng leaf/stem extract produced by subcritical water extraction at high temperature ($190^{\circ}C$) posses higher cytotoxic activity against human cancer cell lines than ethanol extract. Subcritical water extraction can be a great candidate for extraction of functional substance from ginseng leaves/stems.

Effects of Ethanol Addition on the Efficiency of Subcritical Water Extraction of Proteins and Amino Acids from Porcine Placenta

  • Park, Sung Hee;Kim, Jae-Hyeong;Min, Sang-Gi;Jo, Yeon-Ji;Chun, Ji-Yeon
    • Food Science of Animal Resources
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    • v.35 no.2
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    • pp.265-271
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    • 2015
  • In a previous study, hydrolysates of porcine placenta were obtained and the extraction efficiency for proteins and amino acids was compared between sub- and super-critical water extraction systems; optimum efficiency was found to be achieved using subcritical water ($170^{\circ}C$, 10 bar). In this study, the effects of adding ethanol to the subcritical water system were investigated. The lowest-molecular-weight extraction product detected weighed 434 Da, and the efficiency of extraction for low-molecular-weight products was increased when either the concentration of ethanol was decreased, or the extraction time was lengthened from 10 min to 30 min. The highest concentration of free amino acids (approximately 8 mM) was observed following 30 min extraction using pure distilled water. The concentration of free amino acids was significantly lower when ethanol was added or a shorter extraction time was used (p<0.05). Color change of the solution following extraction was measured. There were no significant differences in color between lysates produced with different extraction times when using distilled water (p>0.05); however, using different extraction times produced significant differences in color when using 20% or 50% ethanol solution for subcritical extraction (p<0.05). The range of pH for the hydrolysate solutions was 6.4-7.5. In conclusion, the investigated extraction system was successful in the extraction of $\leq$ 500 Da hydrolysates from porcine placenta, but addition of ethanol did not yield higher production of low-molecular-weight hydrolysates than that achieved by DW alone.

Efficient Flavonoid Extraction from Apple Peel by Subcritical Water and Estimation of Antioxidant Activity (아임계수를 이용한 사과 과피 플라보노이드의 효율적 추출 및 항산화 활성 평가)

  • Cheigh, Chan-Ick;Yoo, Seo-Yeon;Chung, Myong-Soo
    • The Korean Journal of Food And Nutrition
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    • v.24 no.3
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    • pp.458-463
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    • 2011
  • The effect of subcritical water for the extraction of total polyphenols and flavonoids from apple peel was investigated, and then the antioxidant activity of the extracts was estimated. Maximum yields of total polyphenolic compounds($36.4{\pm}1.9mg$ quercetin equivalent(QE)/g dried material) and flavonoids($9.9{\pm}0.8mg$ QE/g dried material) were obtained by subcritical water extraction(SWE) with operating conditions of $190^{\circ}C$, 1,300 psi, and 20 min. Furthermore, the highest antioxidant activity($76.1{\pm}1.1%$) was observed in the extract obtained from SWE using the same conditions. The flavonoids from the SWE of apple peel were compared to three conventional extraction methods in terms of their extraction efficiency and antioxidant activity. The SWE was significantly more effective than hot water ($90^{\circ}C$), methanol, and ethanol extraction for flavonoid yield by 4.7-, 2.2-, and 1.3-fold, respectively, and for antioxidant activity by 11.0-, 4.9, and 2.8-fold, respectively.

Extraction of Reducing Sugar with Anti-Oxidative Scavengers from Peels of Carya cathayensis Sarg.: Use of Subcritical Water

  • Shimanouchi, Toshinori;Ueno, Shohei;Yang, Wei;Kimura, Yukitaka
    • Environmental Engineering Research
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    • v.19 no.1
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    • pp.41-45
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    • 2014
  • The peels of Carya cathayensis Sarg. (PCCS) were treated under subcritical water conditions ($130^{\circ}C$ to $280^{\circ}C$ for 0 to 120 min). The extract from PCCS included reducing sugar, proteins, and compounds with radical scavenging activity. Addressing the reducing sugar that is a resource of bioethanol, we could maximize the reducing sugar under the subcritical water ($190^{\circ}C$ for 60 min) and obtain 0.24 g/g-sample together with 9.7 units/mg-sample of radical scavenging activity. The obtained extract was estimated to correspond to 1 L of bioethanol/100 g-sample. It was therefore considered that the treatment by subcritical water could yield reducing sugar and natural compounds with radical scavenging activity.

Remediation of benzo[a]pyrene Contaminated Soil using Subcritical Water (아임계수를 이용한 토양 내 벤조[a]피렌 정화)

  • Shin, Moon-Su;Islam, Mohammad Nazrul;Jo, Young-Tae;Park, Jeong-Hun
    • Journal of Soil and Groundwater Environment
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    • v.19 no.6
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    • pp.13-17
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    • 2014
  • Subcritical water acts like an organic solvent at elevated temperature in terms of its physicochemical properties. Taking into account this advantage, the remediation experiments of benzo[a]pyrene contaminated soil (8.45 mg/kg of initial concentration) were conducted using subcritical water extraction apparatus. The effect of operating factors on the removal efficiency was studied at the varying the conditions of the water temperature ranging $200{\sim}300^{\circ}C$, extraction time 30~90 min, and flow rate 0.3~2.0 mL/min. 12 g of benzo[a]pyrene contaminated soil was inserted into the extraction cell and placed into the reactor and then the subcritical water was driven through the cell. In this study, the removal efficiency of benzo[a]pyrene was increased from 55.1 to 98.1% when the temperature increased from 200 to $300^{\circ}C$. The removal efficiency was decreased from 97.0 to 77.0% when the flow rate increased from 0.3 to 2.0 mL/min, suggesting that the extraction is limited by intra-particle diffusion. The 30 min reaction time was determined as an effective treatment time at $250^{\circ}C$. Based on the results, the optimum condition for the remediation of benzo[a]pyrene contaminated soil was suggested to be $250^{\circ}C$, 30 min, and 0.3 mL/min.

Antioxidant activities of phenolic compounds from Ziziphus jujuba Mill extract using subcritical water (대추 아임계수 추출물의 폴리페놀 함량 및 산화방지 평가)

  • Ko, Min-Jung;Kwon, Mi-Ri;Chung, Myong-Soo
    • Korean Journal of Food Science and Technology
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    • v.53 no.3
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    • pp.329-333
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    • 2021
  • Subcritical water extraction (SWE) is an eco-friendly extraction method that uses only purified water as a solvent under high temperature and high pressure conditions. In this study, total phenolics, and antioxidant activity were evaluated in Ziziphus jujuba Mill extracts from subcritical water obtained by varying the extraction temperature (110-190℃) and extraction time (1-20 min). Total phenolics was maximized with extraction at 190℃ for 15 min (67.79±3.45 mg gallic acid equivalent/g jujube). The 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity (48.84±4.74%) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) free radical scavenging activity (84.75±1.15%) were maximal at extraction conditions of 190℃, for 20 min. All jujube extracts prepared using SWE had higher total phenolics and antioxidant activities than extracts prepared using organic solvent extraction (60℃, 120 min), including methanol and ethanol. SWE could be an excellent alternative to organic solvents for extracting phenolics and antioxidant compounds.

Influence Factor on Remediation of PAHs-Contaminated Soil by Using Flowing Subcritical Water (흐름식 아임계수를 이용한 PAHs 오염토양 정화 영향인자)

  • Jo, Young-Tae;Islam, Mohammad Nazrul;Park, Jeong-Hun
    • Journal of Soil and Groundwater Environment
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    • v.18 no.4
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    • pp.1-7
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    • 2013
  • Subcritical water which acts as organic solvent with increasing temperature and pressure because dielectric constant and viscosity decrease can be used to remediate PAHs-contaminated soil. Factors influencing on extraction were studied with varying the water temperature $200{\sim}275^{\circ}C$, extraction time 0~90 min, flow rate 10~100 mL/min and pressure 3.9~10MPa. 300 g of soil sample which was contaminated with PAHs(naphthalene, phenanthrene, fluoranthene and pyrene; 423, 420, 539 and 428 mg/kg of initial concentration) was packed into the cell and placed to reactor and then the subcritical water was pumped through the cell for PAHs extraction. Naphthalene was removed almost 100% at relatively low temperature ($200^{\circ}C$). The removal rate of phenanthrene, fluoranthene, and pyrene increased by 8, 26, and 23% when the temperature increased from 200 to $275^{\circ}C$; and it was gradually increased as extraction time increased from 0 to 90 min. Decreasing removal rate when water flow rate increased from 10 to 30 mL/min, but there was no significant change after 30 mL/min. This is supposed due to channeling phenomenon. The pressure was not an effective factor for extraction of PAHs in this study. Based on the results, the importance of effective factor was in following sequence: temperature >> time > flow rate.

Effect of Solvents as Subcritical and Supercritical Fluid on Decomposition and Extraction of Used Automotive Tire (아임계와 초임계유체로써 폐타이어 분해와 추출에 미치는 용매의 영향)

  • Kang, W.S.;Na, D.Y.;Kim, I.S.;Han, S.B.;Park, P.W.
    • Elastomers and Composites
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    • v.34 no.3
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    • pp.239-246
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    • 1999
  • Side wall samples from a used automotive tire were subjected to subcritical and supercritical decomposition and extraction with three solvents, water, 28% ammonia solution and ammonia. For 6mm cube samples the rate of supercritical extraction with water followed a first-order kinetics with an activation energy of 140 kJ/mol. Solvent power of 28% ammonia so lotion at supercritical condition was found to be higher than supercritical water at initial extraction as pressure decreased. These phenomena were considered to be an effect of ammonia involved in water.

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Optimization of operating parameters to remove and recover crude oil from contaminated soil using subcritical water extraction process

  • Taki, Golam;Islam, Mohammad Nazrul;Park, Seong-Jae;Park, Jeong-Hun
    • Environmental Engineering Research
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    • v.23 no.2
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    • pp.175-180
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    • 2018
  • Box-Behnken Design (BBD) under response surface methodology (RSM) was implemented to optimization the operating parameters and assess the removal and recovery efficiencies of crude oil from contaminated soil using subcritical water extraction. The effects of temperature, extraction time and water flow rate were explored, and the results indicate that temperature has a great impact on crude oil removal and recovery. The correlation coefficients for oil removal ($R^2=0.74$) and recovery ($R^2=0.98$) suggest that the proposed quadratic model is useful. When setting the target removal and recovery (>99%), BBD-RSM determined the optimum condition to be a temperature of $250^{\circ}C$, extraction time of 120 min, and water flow rate of 1 mL/min. An experiment was carried out to confirm the results, with removal and recovery efficiencies of 99.69% and 87.33%, respectively. This result indicates that BBD is a suitable method to optimize the process variables for crude oil removal and recovery from contaminated soil.