• 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.

• 한국염색가공학회:학술대회논문집
• /
• 한국염색가공학회 2008년도 제38차 학술발표대회
• /
• pp.114-116
• /
• 2008

Poly(${\varepsilon}$-caprolactone) nanocapsules(nanoPCL) containing phytoncide oil were synthesized by emulsion diffusion method using ethyl acetate as organic solvent. The influence of the degree of hydrolyzation of poly(vinyl acohol) used as an emulsion stabilizer, and the different weight ratio of core material to wall material on the particle size, morphology, and emulsion stability was investigated to design nanocapsules. The encapsulated nanoPCL were characterized by FT-IR spetrometry, Scanning electron microscope, Differential scanning calorimetry, and Thermogravimetry analysis, respectively.

• 한국미생물생명공학회:학술대회논문집
• /
• 한국미생물생명공학회 1986년도 추계학술대회
• /
• pp.523.2-523
• /
• 1986

The hydrolysis of olive oil was attempted with immobilized C. rugosa lipase in the reverse phase solvent system. (i.e. immobilized wet particles is dispersed in continuous phase olive oil or organic solvents containing olive oil). Sephadex LH-20 and LH-60 were used as the supports that can be used in organic solvents. The water content of wet particles of sephadex LH-20 and LH-60 were about 72% (w/w) and 85% (w/w), respectively Both swollen gels with 0.05M buffers adsorbed about 18% of lipase dissolved. They were easily dispersed in liquid olive oil or in organic solvents. The effects of organic solvents on the stability and catalytic activity of the lipase have been examined. The results revealed that isooctane is superior to the other solvents examined for enzymatic fat spliting in reverse phase system. Kinetics of enzymatic hydrolys of olive oil by immobilized lipase has been investigated in a batch reactor. Effects of pH and temperature on the lipase were studied. The substrate concentration was influenced positively on the thermal stability.

• 한국인쇄학회지
• /
• 제15권2호
• /
• pp.1-4
• /
• 1997

Existing cleaning solvent using screen printing are the organic solvents including aromatic compounds carried with poisonous and stench. besides, Cleaning method of current screen printing are for the most part mixed cleaning method of dipping and polish. Using 1,1,1-TCE, CFC-113 alternative system cleaning solvent be substituted for existing cleaning solvent against screen printing ink measured the cleaning efficiency according to gravimetric analysis method and property change of gassamer according to Image Analyzer. Also, Cleaning process system carry with excellent cleaning efficiency studied which was proposed new cleaning process including ultrasonic cleaning process be substituted for existing mixed cleaning method of dipping and polish.

• Advances in nano research
• /
• 제13권2호
• /
• pp.187-197
• /
• 2022

The synthesis of organic and hybrid organic-inorganic perovskites directly from solution improves the cost- and energy-efficiency of processing. To date, numerous research efforts have been devoted to investigating the influence of the various solvent parameters for the synthesis of lead halide perovskites, focused on the effects of different single solvents on the efficiency of the resulting perovskites. In this work, we investigated the effect of solvent blends for the first time on the structure and phase of perovskites produced via the Lewis base vapor diffusion method to develop a new synthetic approach for water-stable CsPbBr₃ particles with nanometer-sized dimensions. Solvent blends prepared with DMF and water-miscible solvents with different Gutmann's donor numbers (D_N) affect the Pb ions differently, resulting in a variety of lead bromide species with various colors. The use of a DMF/isopropanol solvent mixture was found to induce the formation of the Ruddlesden-Popper perovskite based on lead bromide. This perovskite undergoes a blue color shift in the solvated state owing to the separation of nanoplatelets. In contrast, the replacement of isopropanol with DMSO, which has a high DN, induces the formation of spherical CsPbBr₃ perovskite nanoparticles that exhibit green emission. Finally, the integration of acetone in the solvent system leads to the formation of lead bromide complexes with a yellow-orange color and the perovskite CsPbBr₃.

• Bulletin of the Korean Chemical Society
• /
• 제13권6호
• /
• pp.642-647
• /
• 1992

Second-order rate constants have been measured spectrophotometrically for the reactions of substituted phenyl acetates with butane-2,3-dione monoximate and p-chlorophenoxide anions in MeCN-H$_2$O mixtures of varying compositions. The reaction rate, unexpectedly, decreased remarkably upon initial additions of MeCN to H$_2$O up to 30-40 mole ${\%}$ MeCN, and followed by a gradual increase upon further additions of MeCN. The change in solvent composition also influenced the magnitude of the ${\alpha}$-effect, i.e., the ${\alpha}$-effect increased as the mole ${\%}$ MeCN increased. The solvent dependent ${\alpha}$-effect for the present system appears to indicate that the differential solvation between the ${\alpha}$-effect nucleophile and the corresponding normal nucleophile is not solely responsible but the difference in the transition-state stabilization is also responsible for the ${\alpha}$ -effect in organic solvent-rich region.

• 한국산업보건학회지
• /
• 제5권1호
• /
• pp.48-58
• /
• 1995

This study was performed to find out the exposure level of mixed organic solvents, excretion of urinary hippuricacid and subjective symptoms according to the exposure of organic solvents of female workers who works on 5 shoes manufacturing industries in Taejon City from 24, september to 20, october 1993. The studied groups were divided into 3 groups that were consist of direct exposure group(48 workers), indirect exposure group(49 workers) and non-exposure group(68 workers) to the organic solvents. The exposure levels of toluene of direct exposure group which $89.86{\pm}56.20ppm$ had higher than that of indirect exposure group which had $40.23{\pm}47.21ppm$. In the exposure level of mixed organic solvent(R-value), direct exposure group was $2.84{\pm}1.53$ and exceeded approximatly 3 times the R-value. Whereas, indirect exposure group was not exceeded the R-value as $0.80{\pm}0.61$. In the excretion level of urinary hippuric acid, direct exposure group was $1.78{\pm}1.25g/l$, indirect exposure group was $1.22{\pm}0.93g/l$ and non-exposure group was $0.51{\pm}0.18g/l$ respectively. Therefore both direct exposure group and indirect exposure group were significantly higher than non-exposure group(P<0.01). In the correlation between toluene levels and urinary hippuric acid level, the direct exposure group had positive correlation(R=0.8309, P<0.01), also indirect exposure group had positive correlation(R=0.5859, P<0.05) and also in the correlation between the R value of mixed organic solvents and the urinary hippuric acid levels, the direct exposure group had positive correlation(R=0.4492, P<0.05), and indirect exposure group had ositive correlation(R=0.7911, P<0.01). In the complain rates of the worker's subjective symptoms at work, both direct exposure group and indirect exposure group were higher than non-exposure group(P<0.05, P<0.01). But the sujective symptoms of "floating sensation" of direct exposure group had significantly higher than indirect exposure group. In the percent of subjective symptoms complaints during the worker's daily life, both direct exposure group and indirect exposure group had generally more statistical significance than nonexposure group(P<0.01), direct exposure group had not statistical significant difference from indirect exposure group. As the results mentioned above, it has been analysed that the indirect at the adjacent manufaturing process are exposed to the considerable amount of solvent. Therefore, I think that there should be the betterment of surrounding through the complete working environment management to the occurrence source of the organic solvent, the changes of health management system to the indirect-exposed workers, and the systematic management of the special medical examination and the like.

• Environmental Engineering Research
• /
• 제16권1호
• /
• pp.1-9
• /
• 2011

During automotive painting, volatile organic compounds (VOCs) associated with the paint solvents are emitted to the atmosphere. Most VOC emissions come from spraying operations via the use of solvent-based paints, as the spraybooth air picks up gaseous solvent compounds and overspray paint materials. The VOCs consist of aromatic and aliphatic hydrocarbons, ketones, esters, alcohols, and glycolethers. Most VOCs (some hydrophilic VOCs are captured and retained in the water.) are captured by an adsorption system and thermally oxidized. In this paper, the processes involved in automotive painting and in VOC control are reviewed. The topics include: painting operations (briefly), the nature of VOCs, VOC-control processes (adsorption, absorption, biological removal, and thermal oxidation) and energy recovery from VOCs using a fuel reformer and a fuel cell, and the beneficial use of paint sludge.

• 미생물학회지
• /
• 제33권3호
• /
• pp.181-186
• /
• 1997

유기용매계에서 lipase AK를 사용하여 당 ester화합물을 합성하였다. 유기용매로는 당의 용해도가 높고 반응성이 뛰어난 pyridine을, acyl donor로는 vinyl butyrate을 선택하였다. Transesterification반응에 의해 생성된 monobutyryl fructose와 dibutyryl fructose는 TLC 및 GC 분석으로 확인하였다. Transesterification에 미치는 반응조건은 fructose:vinyl butyrate의 비가 1:10(M/M), 반응온도 40^{\circ}C.$, 교반속도 150rpm, 효소량 10mg/ml의 경우가 적당하였으며 반응시간이 길어질수록 전환율이 높아져, 반응 10일 정도에서 전환율은 90% 이상에 도달하였다. 이때 반응 초기에는 monobutyryl fructose가 주로 합성되었으나 시간이 경과함에 따라 dibutyryl fructose의 함량비가 증가하였다. 반응계에 소량의 수분을 첨가하였을 경우에는 반응속도가 감소함과 동시에 반응산물중 dibutyryl fructose의 양은 줄어들고 monobutyryl fructose의 생성량이 증가하는 경향을 보여주었으며, 수분함량 1%에서는 monobutyryl fructose만이 생성되었다.

• Bulletin of the Korean Chemical Society
• /
• 제28권10호
• /
• pp.1818-1820
• /
• 2007