• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3691-3695
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• 2012

Photocatalytic reduction of hexavalent chromium (Cr(VI)) in ferric-tartrate system under irradiation of visible light was investigated. Effects of light resources, initial pH value and initial concentration of various reactants on Cr(VI) photocatalytic reduction were studied. Photoreaction kinetics was discussed and a possible photochemical pathway was proposed. The results indicate that Fe(III)-tartrate system is able to rapidly and effectively photocatalytically reduce Cr(VI) utilizing visible light. Initial pH variations resulte in the concentration changes of Fe(III)-tartrate complex in this system, and pH at 3.0 is optimal for Cr(VI) photocatalytic reduction. Efficiency of Cr(VI) photocatalytic reduction increases with increasing initial concentrations of Cr(VI), Fe(III) and tartrate. Kinetics analysis indicates that initial Fe(III) concentration affects Cr(VI) photoreduction most significantly.

• 한국지반환경공학회 논문집
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• 제13권11호
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• pp.37-42
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• 2012

본 연구는 TBOS를 기질로 적용한 Geobacter lovleyi의 TCE 탈염소화 공정에 관하여 조사하였다. Geobacter lovleiy를 이용한 TCE 탈염소화 반응은 TCE 초기농도와 Geobacter lovleyi 주입량, 초기 TBOS 농도의 독립변수를 수학적으로 표시하였고, 반응표면법(RSM)을 활용하여 모델화하였다. 이 실험들은 Box-Behnken Design(BBD)을 통해 계획된 15개의 실험을 통해 이루어졌다. RSM을 통하여 TCE 제거효율과 독립변수들의 모델식이 도출되었다 : $Y_1$= -11.50(initial concentration of TCE) + 4.25(단백질 양, 주입된 Geobacter lovleyi의 양) - 4.75(initial concentration of TBOS) - ${6.58X_1}^2$ - ${8.583X_3}^2$ + 93.67, $Y_2=-10.92X_1+5.06X_2-4.89X_3-{4.93X_3}^2-2.19X_1X_2+2.54X_1X_3-2.19X_2X_3+16.71$. 도출된 반응모델은 수정결정계수는 각 0.975, 0.934로 1에 가깝게 나타났으며, 모델의 기여율이 높은 것으로 나타났다. 또한, 통계적 분석결과 TCE 탈염소화 효율에 미치는 영향은 TCE 초기농도 > TBOS 초기농도 > 단백질 양의 순으로 나타났으며, 상호항의 영향은 나타나지 않았다.

• KSBB Journal
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• 제10권1호
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• pp.55-62
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• 1995

본 연구에서는 균주로 Saccharomyces ceremszae A Tee 24858을, 초기 당 농도로는 60, 90, 120 및 $150g/\ell$ 을, 1회 발효 시간으로는 1시간 또는 2시간을, 초기 균체농도로는 $17.5g/\ell$ 내지 $53.1g/\ell$ 사이의 값을 사용하여 10회 반복 회분식 실험을 수 행하였다. 이 결과로부터 반복 회분식 실험에서의 평균 초기 균체농도와 에탄올 생산성 사이의 함수 관계를 규명 하여 보았다. 초기 균체농도와 에탄올 생산성 사이의 함수 관계는 초기 균체농도가 증가함에 따라 초기 당 농도에 관계없이 에탄올 생산성이 비 션형적 으로 증가하는 함수 관계를 나타내였다. 초기 당 농도가 $60g/\ell$ 이고, 초기 균체농도가 $34.5g/\ell$ 인 경우 발효는 1시간 내에 완료되었으며 균체의 분리, 새로운 기질의 주입 등의 조작을 고려한 총 10회 반복 회분 실험의 에탄올 생산성은 $26.7g/\ell$.hr이었다. 초기 당 농도가 120gjP 이고 초기 균체농도가 5 50.3gj P 인 경우에도 1시간 내에 발효가 완료되었으 며 이때의 에탄올 생산성은 $48.8g/\ell$.hr이었다. 본 연구에서 수행한 8종류의 10회 반복 회분식 실험을 통하여 얻은 최대 에탄융 생산성은 $53g/\ell$.hr이였다.

• 한국환경과학회지
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• 제11권7호
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• pp.757-763
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• 2002

The objective of this study is to delineate removal efficiency of the Linear alkylbenzene sulfonates(LAS) in solution by $TiO_2$ photocatalytic oxidation as a function of the following different experimental conditions : initial concentration of LAS, $TiO_2$ concentration, UV wavelength and pH of the solution. It was increased with decreasing initial concentration of LAS and with decreasing pH of the solution. Removal efficiency increased with increasing $TiO_2$ concentration but was almost the same at $TiO_2$ concentration of 2 g/L and 3 g/L, i.e., for initial LAS concentration of 50 mg/L. It was removal efficiency was 85% at 150 min in the case of $TiO_2$ concentration of 0.5 g/L but 100% after 150 min in the case of $TiO_2$ concentration of 1 g/L, 100% after 110 min in the case of $TiO_2$ concentration of 2 g/L and 3 g/L. UV wavelength affection on the removal efficiency of LAS decreased in the order of 254, 312 and 365 nm as increasing wavelength. But the removal efficiency of LAS was nearly the same at UV wavelength of 254 nm and 312 nm.

• 생명과학회지
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• 제5권4호
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• pp.155-161
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• 1995

The effects of substrate concentration, enzyme concentration, reaction temperature, and water content were investigated in intramolecular esterification. This study used cyclohexane as organic solvent, power lipase as enzyme, and benzyl alcohol and octanoic acid as substrate. The initial reaction rate was found to be proportional to enzyme concentration; followed Michaelis-Menten equation for octanoic acid; and was inhibited by benzyl alcohol . The observed initial reaction rate first increased, then decreased with increasing reaction temperature, giving rise to the maximum rate at 20$\circ$. The drop in the reaction rate at higher temperature was to partition equilibrium change of substrate between organic solvent and hydration layer of enzyme molecule in addition to the deactivation by enzyme denaturation. Water layer surrounding enzyme molecule seemed to activate in organic solvent and the realistic reaction was done in the water layer. In the enzymatic reaction in organic solvent, the initial reaction rate was influenced by partition quilibrium of substrate, so the optimum condition of substrate concentration, enzyme concentration, reaction temperature, and water content would give a good design tool.

• Journal of Microbiology and Biotechnology
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• 제15권6호
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• pp.1159-1163
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• 2005

The production of hydrogen by Chlamydomonas reinhardtii UTEX 90, a marine green alga, was performed under dark fermentation. The effects of initial nitrogen and phosphorus concentration on the cell growth and the production of hydrogen and organic substances were investigated. In the growth stage, the maximum dry cell weight (DCW) was 3 g/l when the initial ammonium concentration was 15 mM. In the dark fermentation, the maximum hydrogen production was $3.5\;{\mu}mol/\;mg$ DCW when the initial nitrogen concentration was 7.5 mM. The nitrogen concentration had a greater effect on organic compound and hydrogen production than the phosphorus concentration during the dark fermentation. An investigation of the duration of dark fermentation showed that, at least until three days, dark fermentation should be prolonged for maximum hydrogen production.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.313-316
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• 2000

The effects of initial sugar concentration and the various nitrogen sources on the fermentation characteristics of Thraustochytrium aureum were investigated. The sugar conversion ratios decrease with increase in the initial sugar concentration regardless of the kinds of nitrogen sources. The specific growth rate, the biomass yield, and the DHA yield also decreased but approached constant values higher than the concentration of 30g/L. The sugar conversion ratios and the specific growth rate showed the highest values in case of using the yeast extract as nitrogen source. It was difficult to conclude that the variation of nitrogen source had some effects on the biomass yield. However, the initial sugar concentration had a rather effects on the biomass yield for the sugar concentration of 40 g/L showed 0.27. The nitrogen source that showed the greatest yield of DHA was sodium glutamate.

• 한국환경과학회지
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• 제11권4호
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• pp.361-366
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• 2002

Several effects on Pb$^{2+}$ removal by crab shell from aqueous solution were investigated. As the increase of initial Pb$^{2+}$ concentration and decrease of initial crab shell concentration, the time required to reach an equilibrium state and the residual Pb$^{2+}$ concentration increased. In our experimental ranges, the optimum initial Pb$^{2+}$ concentration and crab shell concentration were below 103 mg/$\ell$ and over 0.5 mg/$\ell$, respectively. Also, in order to investigate the mechanism of Pb$^{2+}$ removal by crab shell in aqueous solution, the crab shell was compared with chitosan and chitin on aspects of Pb$^{2+}$ removal capacity and Pb$^{2+}$ removal rate. The Pb$^{2+}$ removal by crab shell was greater than that by chitin and chitosan. The role of chitin was not so great in Pb$^{2+}$ removal by crab shell. The Pb$^{2+}$ removal by chitosan was not exactly correlated to the molecular weight of chitosan. weight of chitosan.

• KSBB Journal
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• 제11권2호
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• pp.125-131
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• 1996

Bacillus amyloliquefacieus 01용한 회분식 배양시 탄소원인 maltose와 glucose에서 저해제 acetic a acid, lactic acid가 세포성장과 생성물 생성에 미치 는 영향에 대해 검토한 결과, acetic acid가 저해제 로 작용함을 확인하였고, acetic acid 첨가시 초기농 도가 증가할수록 세포성장은 현저하게 감소되었다. ${\alpha}$-Amylase 생성 최대치는 maltose $10g/\ell$ 의 경우 a acetic acid 초기농도 $0.5g/\ell$ 일때 24시간 배양시에 l25unit/ml로 가장 높았고, glucose $10g/\ell$ 의 경우 acetic acid 초기놓도 $2.0g/\ell$ 일때 20시간 배양시에 331.55unit/ml로 가장 높았다. Acetic acid 초기농 도가 과량 일때는 세포의 성장이 최저 상태이고, ${\alpha}$-amylase 생성도 급격히 감소하였다. 저해제로 ace­t tic acid 첨가시 탄소원인 maltose와 glucose를 비 교하면 glucose에서 maltose 보다는 세포가 더 성장되었고, ${\alpha}$-amylase의 생성도 더 많게 나타났으며, 두 가지 탄소원에 다같이 저해 작용을 나타냈다.

• KSBB Journal
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• 제10권3호
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• pp.323-334
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• 1995

Hybridoma 세포의 세포 성장 속도, monoclo nal antibody의 생산성 및 세포 대사에 미치는 glucose의 영향이 조사되었다. IgG2,를 생산하는 m mouse-mouse hybridona VIII H-8 세포가 모델로 이용되었다. Glucose 농도에 따른 바성장속도의 변화는 기질저해형식 (substrate inhibition type) 의 성장모델로 나타낼 수 있었다. 초기 glucose 농도 4g/f까지는 최대 세포밀도의 증가를 보여 주었다. Glucose는 세포사망속도에 큰 영향을 나타내었고 glucose 농도와 비사망속도 간에는 반비례의 관계가 성립됨을 보였다. Glucose 농도가 증가될수록 세포의 생존율과 monoclonal an tibody의 생산이 증가되었다. Glucose 놓도가 증가될수록 glucose의 비소비속도가 증가되 었고, 초기 glucose 농도의 증가는 lactate의 총괄 비 생산속도의 증대를 가져왔다. 암모늄 이온의 총괄비 생산속도는 초기 Glucose의 농도에 의존하 였지만 암모늄 이온의 전반적인 생성속도는 초기 glucose 농도에 거 의 무관함을 보여 주었다.