• Nuclear Engineering and Technology
• /
• 제51권3호
• /
• pp.761-768
• /
• 2019

Understanding the phenomena of formation of single drops is necessary to understand the hydrodynamics in solvent extraction equipment which are used for separation of nuclear materials. In this work, the phenomena of aqueous phase and organic phase drop formation at submerged nozzles are compared by conducting experiments with 30%TBP (v/v) in dodecane as the organic phase and nitric acid as the aqueous phase. Two different nozzles and three different nitric acid concentrations are used. For each nozzle and nitric acid concentration, velocity of the dispersed phase is varied. Drops of aqueous phase formed at downward oriented nozzles submerged in organic phase are observed to be smaller than the drops of organic phase formed at upward oriented nozzles submerged in aqueous phase. Correlations to estimate drop diameter are proposed.

• Journal of Microbiology and Biotechnology
• /
• 제7권5호
• /
• pp.345-351
• /
• 1997

An aqueous/organic two-phase reaction system was applied to the production of catechol using immobilized resting cells of Pseudomonas putida CY 400. Water/ethyl ether system was used because of high partition coefficient of catechol and thus to reduce the product inhibition and degradation. Among the tested immobilization carriers, polyacrylamide gel gave the highest catechol productivity. The immobilization seemed to protect the cells against solvent toxicity. From the simulation of reaction conditions based on two-phase models, it was found that there was an optimum acetate concentration at fixed benzoate and cell concentrations for the catechol productivity. A lower phase volume ratio (lower fraction of organic phase) gave a higher productivity. However, the substrate conversion was low at low phase volume ratio.

• 한국미생물·생명공학회지
• /
• 제20권1호
• /
• pp.61-67
• /
• 1992

유기용매 이상계에서의 thermolysin을 사용하여 아스파탐 전구체 합성시 pH, 온도, 기질농도, 그리고 유기용매상에 대한 수용액상의 부비피 ($\alpha$)등의 변화에 따른 기질의 분해 반응, 효소의 안정성, 그리고 Z-APM 합성에 미치는 복합적인 영향을 조사함으로써 반응조건의 최적화를 도모하였다. 유기용매 이상계에서의 L-PM.HCL의 자연분해는 수용액에서보다 훨씬 느리게 일어나며, 또한 $\alpha$가 증가할 수록 분해속도가 감소하는 것을 알 수 있었다.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2000년도 춘계학술발표대회
• /
• pp.145-148
• /
• 2000

Large-scale resolution of epoxides by the yeast Rhodotorula glutinis was demonstrated in an aqueous/organic two-phase cascade membrane bioreactor. Due to the chemical instability and low solubility of epoxides in aqueous phases, an organic solvent was introduced into the reaction mixture in order to enhance resolution of epoxide. A cascade hollow-fiber membrane bioreactor was used (i) to minimize the toxicity of organic solvents towards the epoxide hydrolase of Rhodotorula glutinis, and (ii) to remove inhibitory amounts of formed diol from the yeast cell containing aqueous phase. Dodecane was selected as a suitable solvent and 1,2-epoxyhexane as a model substrate. By use of this membrane bioreactor, highly concentrated (0.9 M in dodecane) enantiopure (>98% ee) (S)-1,2-epoxyhexane (6.5 g, 30% yield) was obtained from its racemic mixture.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
• /
• pp.73-76
• /
• 2000

A novel, continuous bioreactor system combining a bubble column (absorption section) and a two-phase bioreactor (degradation section) has been designed to treat a gas stream containing benzene. The bubble column contained hexadecane as an absorbent for benzene, and was systemically chosen considering physical, biological, environmental, operational and economic factors. This solvent has infinite solubility for benzene and very low volatility. After absorbing benzene in the bubble column, the hexadecane served as the organic phase of the two-phase partitioning bioreactor, transferring benzene into the aqueous phase where it was degraded by Alcaligenes xylosoxidans Y234. The hexadecane was then continuously recirculated back to the absorber section for the removal of additional benzene. All mass transfer and biodegradation characteristics in this system were investigated prior to operation of the integrated unit, and these included: the mass transfer rate of benzene in the absorption column, the mass transfer rate of benzene from the organic phase into the aqueous phase in the two-phase bioreactor, the stripping rate of benzene out of the two-phase bioreactor, etc. All of these parameters were incorporated into model equations, which were used to investigate the effects of operating conditions on the performance of the system. Several experiments were conducted to show the feasibility of this system. This process is believed to be very practical for the treatment of high concentrations of gaseous pollutants.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 추계학술대회 논문집
• /
• pp.515-518
• /
• 1997

Resident time of the centrifugal extractor for organic phase extraction using a height controlled separator weir and a divert plate is the important factor that affects significantly the chemical material extraction and the productivity in the chemical and mechanical processes. In this paper, it describes the design of the device for extraction of an organic phase from radioactive wastes, and considers phase separating weir and divert disk, both being designed to be adjustable in their positions, for effectively separating an organic phase. A height-adjustable separating weir unit used for separating the organic phase from the aqueous phase using a phase separating weir and designed to control the height of the separating weir as desired so as to allow the weir to be positioned at a boundary layer between two separated phases. The centrifugal extractor controls satisfactorily the mixed reaction time of two phases within the separator regardless of the variations of the mixing ratio of the two phases and the rotating speed of the extractor, is designed to be adjustable in its position in the vertical direction, thus allowing the user to appropriately select the mixed reaction time of the two phases within the extractor as desired. From development of a centrifugal extractor, it can effectively recover such usable elements, and preferably reducing the output quantity of radioactive wastes.

• Korean Chemical Engineering Research
• /
• 제55권1호
• /
• pp.130-134
• /
• 2017

Organic aerosols dispersed in the atmosphere likely undergo phase separation. Such internally mixed particles are often described as comprising an organic phase and an aqueous phase separately. We studied the morphology of two liquid separated aerosols in the sub-microscale by using a simple thermodynamic model with Russian doll geometry. The morphology of particles can be easily predicted from the simple criteria on the surface tension and two algebraic equations (the volume constraint and Young equation). This result may give the potential explanation about the complex morphology of the organic airborne particles.

• 대한화학회지
• /
• 제38권6호
• /
• pp.449-455
• /
• 1994

효소를 이용한 생리활성 펩티드의 합성 연구에 관한 기초자료를 얻기 위하여, Kyotorphin(진통작용을 가진 펩티드) 유도체가 $\alpha-chymotrysin$를 이용한 이상계(two phase system;유기상과 수용액상)조건하에서 Ac-Tyr-OH 와 $Arg-NH_2$로부터 합성되었다. Ac-Tyr-OH(10 mM)과 $Arg-NH_2$ (20 mM)와의 Kyotorphin 유도체 합성에 대한 유기용매의 효과에서 ethyl acetate계에서의 합성 수율이 다른 유기용매(dichloromethane, n-butanol, n-hexane, chloroform)에서 보다도 더 높았다. Kyotorphin 유도체의 합성에 미치는 최적조건을 보면, 효소 농도는 10 ${\mu}M$, 온도 및 pH는 각각 $35^{\circ}C$ 및 7.0이었으며, 유기상/수용액상의 비$(\alpha)$는 15였다. Kyotorphin 유도체 합성의 최적 반응조건하에서 수율은 70.2%였으며, 이때의 반응은 24시간 후에 평형에 도달하였다.

• Journal of Microbiology and Biotechnology
• /
• 제14권5호
• /
• pp.932-937
• /
• 2004

In situ extraction by organic solvent was studied in order to improve the recovery yield of hydrocarbon from the culture of Botryococcus braunii, a green colonial microalga. When the solvent mixture of octanol as an extractive solvent and n-octane as a biocompatible solvent was added to a two-phase column, the algal growth was seriously inhibited, even at a low concentration of polar octanol. Therefore, a two-stage cell-recycle extraction process was proposed to improve the contact area between the organic phase and the aqueous phase. The hydrocarbon recovery with in situ cell-recycle extraction showed a three-fold increase (57% of cell) in yield over that with two-phase extraction. In addition, over 60% of the hydrocarbon could be recovered without serious cell damage by downstream separation when this process was applied to the culture broth after batch fermentation.

• 한국미생물·생명공학회지
• /
• 제20권1호
• /
• pp.73-78
• /
• 1992

Tryptophanase를 이용하여 트립토판 합성시 인돌의 효소활성 저해를 억제하기 위하여 유가식 조업, 유기용매 이상계의 사용, 그리고 cyclodextrin의 첨가등에 대하여 연구하였다. 효소 농도가 0.5mg/ml일때 인돌 농도 0.4mM 부근에서 트립토판 생성이 가장 빨랐으며 그 이상에서는 효소활성이 심한 저해를 받았다. 초기 인돌 농도가 20mM일 때는 27시간 반응후 인돌의 전환율이 20인데 비하여 반응기내 인돌 농도를 5mM 이하로 유가식 조업을 하였을 때 전환율이 80%로 향상되었다.