• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.7 no.1
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• pp.17-23
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• 2009

Dihexyloctanamide(DHOA) was used as an extractant or phase modifier with the diamide extractants in a solvent extraction process for a radioactive liquid waste treatment. The degradation compounds of the DHOA extractant, irradiated with $^{60}Co$ gamma ray, were octanoic acid and dihexylamine which are identified by a Fourier transform infrared(FT-IR) and gas chromatograph/mass spectrometer(GC/MS) analysis, and determined by the GC/MS with selected ion monitoring(SIM) mode. Retention behavior of octanoic acid, tridecane (internal standard) and dihexylamine in total ion chromatogram (TIC) were 8.65 min., 9.79 min., and 10.27 min., respectively. With increasing the absorbed dose of the $\gamma$-ray irradiated DHOA, the concentration of octanoic acid was decreased and that of dihexylamine was increased.

• The Korean Journal of Food And Nutrition
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• v.20 no.2
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• pp.120-124
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• 2007

The thermal degradation kinetics of alpha-, gamma- and delta-tocopherols was studied during heating at 100, 150 200 and 250$^{\circ}C$ for 5, 15, 30 and 60 min in the absence of oxygen. The tocopherols were separated by HPLC using a reversed phase ${\mu}$-Bondapak C$_{18}$-column with two kinds of elution solvent system in a gradient mode. The kinetics for degradation of ${\alpha}$-, ${\gamma}$- and ${\delta}$-tocopherols was analyzed as a function of temperatures and times. The degradation of tocopherols was described by the first-order kinetics in the absence of oxygen. The rate of tocopherols degradation was dependent on heating temperatures. The degradation rate constants for ${\alpha}$-, ${\gamma}$ and ${\delta}$-tocopherols showed an increasing trend as the heating temperature increased. The magnitude order of the experimental activation energy was ${\delta}$->${\gamma}$->${\alpha}$-tocopherol.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.4
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• pp.392-399
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• 1998

Nitrogen fertilizers such as urea are readily hydrolyzed in soils to produce ammonium ions which pass through nitrification and denitrification processes. These serial processes have drawn attention due to nitrogen losses, eutrophication, blue baby syndrome, and ozone depletion problems. The purpose of this study was to test the inhibitory effects of hot-water extract and organic solvent fractions of Artemisia asiatica leaves on soil urea hydrolysis and nitrification. In addition, the effects of organic solvent fractions on urease activity and ureolytic bacterial population were also investigated. First, hot-water extract of Artemisia asiatica leaves inhibited soil nitrification substantially with a marginal stimulatory effect on soil urea hydrolysis. Soils treated with hot-water extract of Artemisia asiatica leaves showed significant decreases in the accumulation of soil $NO_3-N$ (~68% decrease) compared with the control soil without the treatment of hot-water extract. In contrast, $CHCl_3$/MeOH fraction and basic aqueous layer of Artemisia asiatica leaves inhibited soil urea hydrolysis very strongly, causing 5.8 and 4.3-fold higher accumulation in amounts of remaining urea-N compared with the non-treated soil. Meanwhile, non of the organic solvent fractions showed any significant effects on soil nitrification inhibition. The inhibition of ureolytic bacterial activity by $CHCl_3$/MeOH fraction and aqueous basic layer of Artemisia asiatica leaves without any effects on urease activity itself led us to conclude that the inhibitions of soil urea hydrolysis were caused by the antagonistic effects on ureolytic bacterial activity.

• Journal of Soil and Groundwater Environment
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• v.11 no.5
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• pp.35-42
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• 2006

The following results were obtained in the reductive degradation of hexachloroethane (HCA), and surface characteristics by using iron sulfide ($FeS,\;FeS_{2}$) mediators. HCA was degraded to pentachloroethane (PCA), tetrachloroethylene(PCE), trichloroethylene(TCE) and cis-l,2-dichloroethylene (cis-1,2-DCE) by complicated pathways such as hydrogenolysis, dehaloelimination and dehydrohalogenation. FeS had more rapid degradation rates of organic solvent than $FeS_{2}$. In liquidsolid reaction, the reaction rates of organic solvents were investigated to explain surface characteristics of FeS and $FeS_{2}$.. To determine surface characteristics of FeS and $FeS_{2}$, the specific surface area and surface potential of each mineral was determined and the hydrophilic site ($N_{s}$) was calculated. The specific surface area ($107.0470m^{2}/g\;and\;92.6374m^{2}/g$) and the $pH_{ZPC}$ of minerals ($FeS\;PH_{ZPC}=7.42,\;FeS_{2},\;PH_{ZPC}=7.80$) were measured. The results showed that the Ns of FeS and $FeS_{2}$ were $0.053\;site/mm^{2}\;and\;0.205\;site/mm^{2}$, respectively. $FeS_{2}$ had more hydrophilic surface than FeS. In other words, FeS have more hydrophobic surface site than $FeS_{2}$.

• KSBB Journal
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• v.16 no.6
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• pp.527-532
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• 2001

Trichlooethylene (TCE) has become a widespread contaminant in air, soil, and underground water due to extensive industrial used and improper disposals. Since TCE is a suspected carcinogen and constitutes public health concerns, many treatment systems have been investigated to remove this hazardous waste. One of the most premising reactor systems for the treatment of TCE is trickling biofilter (TBF), in which monooxygenase (MO), the corresponding enzyme for initiating primary substrate oxidation, fortuitously degrades TCE via cometabolism. TCE, however, is not easily treated by simple TBF. This is mainly due to the toxicities of TCE and its degradation products to microbial film in TBF. In this paper, recent progresses on the development of bioreactor system for the treatment of TCE, especially gas-phase TCE, are reviewed. The potentials of novel biofilm reactor systems were also discussed for the long-term continuous treatment of TCE.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.10a
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• pp.151-151
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• 2003

토양에 방치된 농업용 폐비닐은 거의 분해가 되지 않으며, 수분과 공기의 유통을 차단하고 토양 내 미생물들의 흐름을 막아 토양을 더욱 황폐화시키게 된다. 불법적인 소각 때는 산불의 위험에다 다이옥신, 염소 및 염화수소가스 등을 배출해 대기오염을 유발시킨다. 폐비닐을 열분해과정으로 처리하여 아주 작은 입자로 미분쇄하고 겔상태로 용융된 원료물질속으로 완전히 균일하게 혼합하여 골재로 활용하는 과정에서 가스상과 액상의 여러 가지 중간생성물질이 발생하게 되며, 농약의 살포에 의한 잔류농약 둥 인체에 유해가능한 요소들이 있을 수 있다. 본 연구에서는 개발공정이나 제품에서 인체에 영향을 미칠 수 있는 물질에 대하여 유해성을 평가하고 용응 겔 및 가스와 오일에 함유된 화학성분을 분석하였기에 보고하고자 한다 시험동물의 혈액생화학적 검사에서는 농업용 폐비닐물질 및 열분해 파생물질의 혈청 Cholesterol, 혈청 Alanine aminotranseferse와 Aspartate aminotransferse, Albumin 수치, LDH, Glucose, Uric acid, A/C 비 등의 생화학적 활성도를 측정한 결과들에서는 농업용 폐비닐물질을 투여한 시험군에서 나타난 결과와 비교하여 열분해 파생물질을 투여한 시험군에서 나타난 결과가 감소된 통계결과를 보였다. 이 결과들은 농업용 폐비닐물질을 투여한 시험군보다 열분해 파생물질을 투여한 시험군의 외부독성물질 투여에 의한 생체독성의 영향과 생체에 가해진 스트레스강도가 작았음을 의미하는 것이다. 잔류농약분석에서는 시료로부터 농약을 추출하는 용매추출과정, 시료추출물 중 공존하는 방해성분을 제거하는 정제과정, 폐비닐물질 및 열분해 파생물질 성분을 100mg/kg 이상군의 투여 후 시험동물의 부검시 모든 투여군에서 독성소견이 인정되지 않았다. 이와 같은 결과로 열분해 및 연소과정에서 발생하는 파생물질의 분석결과를 응용하여 대기오염을 방지하고 인체 유해물질을 차단하는 공해 방지 설계의 기초자료를 제안하고자 한다.

• Journal of the Korean Chemical Society
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• v.17 no.2
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• pp.130-135
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• 1973

The rate-constants of hydrolysis of 3, 4-methylenedioxyphenylmethylenemalononitrile are determined by ultraviolet spectrophotometry at various pH and a rate equation which can be applied over wide pH range is obtained. The rate equation reveals that below pH 5.0 and above pH 9.0, the hydrolysis is initiated by the addition of water and hydroxide ion respectively. However, at pH 6.0-8.0 the competitive addition of water and hydroxide ion occurs. The catalytic contribution of hydroxide ion and water can be fully explained by the rate equation obtained.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.849-856
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• 1992

We prepared a simple, economic and versatile preparative system for an enantiomeric separation. Hydrophobic amino acid enantiomers were resolved in the preparative scale by a centrifugal liquid chromatography on the N-hexadecyl-L-proline coated reversed phase. The factors controlling the retention and resolution of racemic amino acids such as the concentration of Cu(Ⅱ), pH of the eluent, the type and content of organic modifier, and rpm of CLC were examined. Several mg of hydrophobic amino acid enantiomers were separated preparatively. To separate all of different amino acid enantiomers, various coating material will be investigated.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.11
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• pp.1465-1471
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• 2007

Response surface methodology (RSM) was employed to optimize extraction conditions in order to find the maximal functional properties of fluid Cheonggukjang. Based on central composite design, a study plan was established with variations of microwave power, ethanol concentration, and extraction time. Regression analysis was applied to obtain a mathematical model. The maximum inhibitory of tyrosinase activity was found as 26.75% at the conditions of 30.56W microwave power, 2.40 g/mL of ratio of solvent to sample content and 10.00 min extraction time, respectively. The maximum superoxide dismutase (SOD)-like activity was 53.23% under the extraction conditions of 108.42 W, 4.38 g/mL and 7.84 min. Based on superimposition of three dimensional RSM with respect to extraction yield, inhibitory of tyrosinase activity and SOD-like activity obtained under the various extraction conditions, the optimum ranges of extraction conditions were found to be microwave power of $55{\sim}75$ W, ratio of solvent to sample content of $2{\sim}5$ g/mL and extraction time of $3.5{\sim}15$ min, respectively.

• Journal of Soil and Groundwater Environment
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• v.6 no.2
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• pp.39-47
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• 2001

According to a series of batch-scale washing tests, SDS+$POE_5$ and $POE_5$+$POE_14$ were determined for the applicable mixed surfactants. Because SDS+$POE_5$ showed slightly negative effects on the microbes in the toxicity tests, $POE_5$+$POE_14$((1:1) 1%) was chosen for this study. In the in-situ flushing experiments, the removal rate of endosulfan was 67% for the injection rate of 1.5L/min/$\textrm{km}^2$. And when methanol and ethanol were added as cosolvent, 75% and 81% removal efficiencies were achieved, respectively. In the tests of bioremediation after the application of in-situ flushing, the removal rates of contaminated soils having 13mg/kg dry soil and 3mg/kg dry soil as initial concentrations were 86% and 81%, respectively. There were no significant degradation after 24 hours. The major rate-limiting factor for the biodegradation of endosulfan might be the mass transfer from soil phase to liquid phase after 24 hours. With the addition of surfactant, 89% removal was achieved after 120 hours. Because the surfactant improved the mass transfer rate, the biodegradation of endosulfan was enhanced. When surfactant and cosolvent were added together, the adaptation period of microorganisms to the surfactant became longer and the removal rates were 84% and 83% for methanol and ethanol, respectively.