• 제목/요약/키워드: dehydration reaction

검색결과 196건 처리시간 0.025초

Effects of Cooking Time and HTST Air Dehydration Time on Physical Propertiesof Driet Green Peas

  • 김명환
    • 한국식품영양과학회지
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    • 제19권3호
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    • pp.195-200
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    • 1990
  • Effects of cooking time(5-30 min in a pressure cooker) and HTST air dehydratiion time(0-9min at 15$0^{\circ}C$) on physical properties of dried green peas(3% oisture content wet basis) were investigated by determining rehydration ratio rehydration curve browning reaction and puncture force, The rehydration ratio and curve of dried green peas were increased with increa-sing cooking time and HTST air dehydration time. Preheating of the green peas for 30 min in a pressure cooker or for 9 min of HTST air dehydration time prior to 6$0^{\circ}C$ air dehydration recovered a 87.3% of original moisture content of raw green peas in a boiling water for 5 min. The brownin greaction was gradually decreased up to 15 min of cooking time. Puncture pressure of rehydrated green peas treated in a boiling water for 5 min was decreased as the cooking time and HTST air dehydration time were increased and was highly correlated with rehydration (r=-0.956) The effects of cooking time and HTST air dehydration time on rehydration ratio browning reaction and puncture pressure were significantly different at the a=0.01 level except effect of HTST air dehydration time on browning reaction.

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Na2B4O7·10H2O/Na2B4O7·5H2O 계의 열분해 탈수반응 및 내구성 고찰 (The Characteristics of the Dehydration Reaction and the Durability for the Thermal Decomposition in Na2B4O7·10H2O/Na2B4O7·5H2O System)

  • 최호상;박영태
    • 공업화학
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    • 제10권6호
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    • pp.885-888
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    • 1999
  • 본 연구에서는 $Na_2B_4O_7{\cdot}10H_2O/Na_2B_4O_7{\cdot}5H_2O$ 반응계의 열분해 탈수반응에 의한 반응속도상수를 결정하고 반응계의 재현성 및 화학축열재의 반복사용에 따른 내구성을 검토하였다. 반응계의 열분해 탈수반응의 차수는 1차이었고, 열분해 탈수 반응속도는 수증기의 분압차에 정비례하였다. 반응계의 반응속도상수는 약 0.27이었고, 반응속도상수와 반응차수에 대한 반응의 재현성이 우수하였다. 또한 화학축열재의 내구성은 연속적으로 반복 사용하여도 활성변화는 ${\pm}5%$ 범위 내에 있었다.

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Response Surface-Optimized Isolation of Essential Fatty Acids via Castor Oil Dehydration

  • Suratno, Lourentius;Imanuel, Anugerahwan;Brama, Andika;Adriana Anteng, Anggorowati;Ery Susiany, Retnoningtyas;Kiky Corneliasari, Sembiring;Wiyanti Fransisca, Simanullang
    • 대한화학회지
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    • 제67권1호
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    • pp.28-32
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    • 2023
  • The reaction conditions optimization, including the temperature of the reaction, amount of catalyst required, and reaction time for the linoleic acids (LAs) and conjugated linoleic acids (CLAs) production by catalytic dehydration of castor oil via saponification was investigated by response surface methodology (RSM). It was confirmed that all three parameters (temperature, time, and amount of catalyst) were influential factors in isolating LAs and CLAs. When the temperature was increased, the iodine value increased, and the reaction time and catalyst amount increased. The optimal reaction conditions were: 240 ℃, 2.2 h reaction time, and 7 wt% catalyst amount. The maximum iodine value reached 156.25 with 91.69% conversion to the essential fatty acids.

하동카오린의 열분해속도에 관한 연구 (Kinetics of Thermal Dehydration of Ha-dong Kaolin)

  • 박희찬;손명모
    • 한국세라믹학회지
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    • 제18권1호
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    • pp.35-40
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    • 1981
  • The kinetics of the dehydration of Ha-dong kaolin was studied isothermally at various temperatures. Dehydration rate was measured by thermogravimetry method in the temperature range of 440~50$0^{\circ}C$ and the particle size range of 170~325mesh. The general equation f($\alpha$)=kt, where $\alpha$ is the fraction reacted in the time and the function f($\alpha$) depends on the reaction mechanism, was applied to this reaction. The function, f($\alpha$) was obtained by application of reduced-time plot and plot of lnln (1-$\alpha$) vs. ln (time), and expressed as (1-$\alpha$) ln (1-$\alpha$)+$\alpha$=kt. The dehydration followed the diffusion-controlled reaction model and gave activation energy of 30Kcal/mole.

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소성Dolomite 수화물계의 축열시스템에 관한 연구 - 소성Dolomite 탈수반응층의 전열해석 - (A Study on Heat Storage System Using Calcined Dolomite - Numerical Analysis of Heat Transfer in Calcined Dolomite Dehydration Packed Bed -)

  • 박영해;김종식
    • 한국태양에너지학회 논문집
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    • 제23권1호
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    • pp.29-38
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    • 2003
  • To develope chemical heat pump using available energy sources, solar heat and other kinds of waste thermal energy, we have studied the material and heat transfer rate in the cylindrical bed reactor packed with Calcined Dolomite. Our results from the studies are as follows ; 1 The time needed to complete dehydration reaction at the wall side of the cylindrical reactor(r/rL=0.5) was shorter than that of the center(r/rL=0.0) as much as 12%. 2. Two dimensional (radial and circumferential) partial differential equations, concerning heat and mass transfer rate in the packed bed of calcined Dolomite, are solved numerically to describe the characteristics of the reaction in the cylindrical reactor. The solution reads rate of reaction in the packed bed reactor depends on the temperature and concentration of reactants. These results read the supplied heat transfers from the wall side of the cylinder to the center, dehydration reaction begins at the inner side of the wall of the cylindrical reactor and the dehydration reaction proceeds from the wall side to center of cylinder.

Synthesis of 1, 1-Diheteroaryl Ethylenes by a Tandem Appel's Dehydration/Thermal Rearrangement Methodology

  • 이기정;허 열;전종갑
    • Bulletin of the Korean Chemical Society
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    • 제20권3호
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    • pp.341-344
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    • 1999
  • The hydrazones of 2-acetylfuran, 2-acetylthiophene, and 2-acetylpyrrole, were allowed to react with S-methylthioacetimidate hydroiodide (8) to give azinoureas 10, and the reaction of 10 with Appel's dehydration conditions (triphenylphosphine/carbon tetrachloride/triethylamine) led to the corresponding azinocarbodiimides 11, which underwent thermal rearrangement under the reaction conditions to give 1,1-diheteroaryl ethylenes 13.

반응표면 분석법을 이용한 마늘 열풍건조 공정의 최적화 (Development of Optimum Processing Conditions in Air Dried Garlics Using Response Surface Methodology)

  • 김명환;김병용
    • 한국식품영양과학회지
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    • 제19권3호
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    • pp.234-238
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    • 1990
  • The effects of salt concentration immersion time in a salt solution prior to air dehydration and heating of air temperature during dehydration upon the browning reaction and pyruvic acid content of air dried garlics to a 6.5% moisture content(wet basis) were analyzed by a response surface methodology(RSM), Those values were also predicted by using a second degree polynomial regression model. Heating of air temperature was the most significant factor affecting the both browning reaction and pyruvic acid content. Salt concentration had more influence to browning reaction than immersion time whereas immersion time was more impor-tant factor than salt concentration on a retention of pyruvic acid sugested different processing conditions. While the processing conditions to minimize the browning reaction(O.D=0.009) were 0.3% of salt solution 9 min of immersion time and 5$0^{\circ}C$ of air temperature compared to control(O.D=0.022) of air dehydration at 5$0^{\circ}C$ Pyruvic acid contents were maximized(174 $\mu$mole/g garlic solid) at the 0.1% of salt solution 3 min of immersion time and 5$0^{\circ}C$ of air temperature compared to control(147 $\mu$mole/g garlic solid) of air dehydration at 5$0^{\circ}C$

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DFT Study on the Different Oligomers of Glycerol (n=1-4) in Gas and Aqueous Phases

  • Valadbeigi, Younes;Farrokhpour, Hossein
    • 대한화학회지
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    • 제57권6호
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    • pp.684-690
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    • 2013
  • Since a glycerol molecule has three active sites, two ${\alpha}$ and one ${\beta}$ hydroxyl groups; it undergoes condensation by releasing water molecules to produce linear, nonlinear and heterocyclic oligomers. The Gibbs free energy (G), enthalpy (H) and internal energy (E) of 7 diglycerol, 15 triglycerol and 23 tetraglycerol isomers were calculated at B3LYP level of theory using 6-311++G(d, p) basis set, in both gas and aqueous phases. Linear oligomers, ${\alpha}{\alpha}$-diglycerol, ${\alpha}{\alpha}$, ${\alpha}{\alpha}$-triglycerol and ${\alpha}{\alpha}$, ${\alpha}{\alpha}$, ${\alpha}{\alpha}$-tetraglycerol, were found to be the most stable oligomers in aqueous phase. It was found that the stability of cyclic oligomers decreases as the size of their rings increases. Cyclic oligomers are produced by dehydration of the acyclic ones which is an endothermic reaction while its ${\Delta}G$ is negative. The dehydration reaction is less endothermic in aqueous phase.