• 한국대기환경학회지
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• 제23권1호
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• pp.39-49
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• 2007

In this study, the performance characteristics of solid phase microextraction (SPME) were investigated for three major odorous groups that consist of 10 individual compounds ([1] volatile organic compounds (VOC): benzene, toluene, p-xylene and styrene, [2] reduced sulfur compounds (RSC): hydrogen sulfide, methyl mercaptan, dimethylsulfide (DMS), dimethyldisulfide (DMDS), and carbon disulfide, and [3] amine: trimethylamine (TMA)). For the purpose of a comparative analysis, two types of SPME fiber ([1] polidimethylsiloxane/divinilbenzene (P/D) and [2] $Carboxen^{TM}$/polidimethylsiloxane (C/P)) were test ε d against each other for a series of standards prepared at different concentration levels (100, 200, and 500 ppb). To compare the analytical performance of each fiber, all standards were analyzed for the acquisition of calibration data sets for each compound. The results of P/D fiber generally showed that its calibration slope increased as a function of molecular weight across different VOCs; however, those of C/P fiber showed a fairly reversed trend. Besides, we confirmed that the application of SPME is limited to many sulfur compounds; only two compounds (DMS and DMDS) are sensitive enough to draw calibration results out of SPME. The calibration data for RSC show generally enhanced slop values for C/P relative to P/D fiber. However, in the case of TMA, we were not able to find a notable difference in their performance.

• Biomolecules & Therapeutics
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• 제5권2호
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• pp.125-132
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• 1997

Cisplatin, a platinum-complex, is currently one of the most effective compounds used in the treat-ment of solid tumors. However, its use is limited by severe side effects such as renal toxicity. Our platinum-based drug discovery program is aimed at developing drugs capable of diminishing toxicity and improving selective cytotoxicity. We synthesized new Pt (II) complex analogue containing 1,2-diaminocyclohexane (DACH) as carrier ligand and 1,2-bis (diphenylphosphino) ethane (DPPE) as a leaving group. Furthermore, nitrate was added to improve the solubility. A new series of [Pt(cia-DACH)(DPPE)] . $2NO_3$ (PC) was synthes-ized and characterized by their elemental analysis and by various spectroscopic techniques [infrared (IR), $_{13}$carbon nuclear magnetic resonance (NMR)] .PC demonstrated acceptable and significant antitumor activity against SKOV-3 and OVCAR-3 human ovarian carcinoma cell lines as compared with that of cisplatin. The cytotoxicity of PC in normal cells was found quite less than that of cisplatin using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), ($^3$H)thymidine uptake and glucose consumption tests in rabbit renal proximal tubular cells, human renal cortical cells and tissues. In conclusion, PC is considered to be more selective cytotoxicity toward human ovarian cancer cells than normal human/rabbit kidney cells.

• 상하수도학회지
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• 제28권2호
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• pp.151-160
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• 2014

Capacitive deionization(CDI) has many advantages over other desalination technologies due to its low energy consumption, less environmental pollution and relative low fouling potential. The objectives of this study are evaluate the performance of CDI which can be used for dissolved salts removal from sewage. To identify ion selectivity of nitrate and phosphate in multiionic solutions and adsorption/desorption performance related to applied potential, a series of laboratory scale experiments were conducted using a CDI unit cell with activated carbon electrodes. The CDI process was able to achieve more than 75 % TDS and $NO_3{^-}$, $NH_4{^+}$ removals, while phosphate removal was 60.8 % and is inversely related in initial TDS and $HCO_3{^-}$ concentration. In continuous operation, increasing the inner cell pressure and reduction of TDS removal ability were investigated which are caused by inorganic scaling and biofouling. However a relative mild cleaning solution(5 % of citric acid for calcium scaling and 500 mg/L of NaOCl for organic fouling) restored the electrochemical adsorption capacity of the CDI unit to its initial level.

• 한국염색가공학회지
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• 제6권2호
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• pp.10-16
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• 1994

Neutral salts have negative or positive effects on the rates of many chemical reactions and also on the rates of acidic and alkaline hydrolysis of carboxylic esters. The direction of neutral salt effects on the hydrolysis of ester depends on the charge of esters. Neutral salts accelerate alkaline hydrolysis of esters with negative charge, but decelerate alkaline hydrolysis of esters with positive charge, and have little effect on the alkaline hydrolysis of neutral esters. It is expected that the rate of the alkaline hydrolysis of Poly(ethylene terephthalte) (PET), polymeric solid carboxylic polyester with carboxyl end group at the polymer end, is also influenced positively by neutral salts. In the present work, to clarify the mechanism of the neutral salt effect on the alkaline hydrolysis of PET, many salts with different anions like NaF, NACl, NaBr, NaI were added to the aqueous alkaline solutions. Then PET was hydrolyzed with aqueous solutions of many salts in alkali metal hydroxides under various conditions. Some conclusions obtained from the experimental results were summarized as follows. The reaction rate of the alkaline hydrolysis of PET was increased by the addition of neutral salts and In k was increased nearly linearly with the square root of ionic strength of reaction medium. This fact suggested that the ionic strength effect by Debye-Huckel and Bronsted theory was exerted on the reaction. The specific salt effect was also observed. The reaction rate was increased with the decrease in the nucleophilicity of anions of neutral salts, i.e., in the order of $F^-$ <$Cl^-$<$Br^-$<$I^-$. It was thought that the reaction rate was increased in the order of $F^-$ <$Cl^-$<$Br^-$<$I^-$. because the completion of anions with $OH^-$ for carbonyl carbon became weaker with the decrease in the nucleophilicity and with the increase in the size of anions.

• 유기물자원화
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• 제6권2호
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• pp.31-44
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• 1998

돈분 슬러리와 톱밥 혼합물을 퇴비화 급속(분해)과정의 파이로트 규모 반응조 성능 평가를 입증하기 위해 간헐통기법으로 퇴비화 처리했다. 계측은 퇴비온도, 산소와 탄산가스농도, 통기량 및 암모니아가스 배출 등의 측정으로 구성됐다. 퇴비화 급속과정의 암모니아 농도는 14일째에 수준이하(I)보다 최적수준(II)부근에서 신속하게 허용범위 34-40ppm 이내로 감소되어 짐을 알 수 있었다. 암모니아가스 저감에 있어서 수분(55-65%), 탄질비(20-40%), 수소이온농도(7-8%) 및 퇴비온도(<$60^{\circ}C$) 등의 최적수준 영향은 상업용 퇴비화에 무시 할 수 없었다.

• 대한환경공학회지
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• 제22권12호
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• pp.2107-2113
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• 2000

세 가지 비이온계 계면활성제(Brij 30, Tween 80, Triton X-l00)의 독성 평가와 polycyclic aromatic hydrocarbons(PAHs)의 생분해에 미치는 영향을 조사하였다. 사용된 세 가지 계면활성제 중에서 Brij 30이 가장 생분해가 잘 되는 것으로 나타났으며, 1.5 g/L까지 아무런 기질 저해 효과가 나타나지 않았다. 이는 사용된 계면활성제가 미생물에 탄소원으로 이용된다는 것을 나타낸다. 수용액상에서 naphthalene과 phenanthrene은 60시간 안에 완전히 분해되었지만 naphthalene의 경우 상당량이 휘발에 의해 손실됨을 알 수 있었다. 슬러리상에서 제어단계는 모래 슬러리의 경우 미생물에 의한 생분해였고, 점토 슬러리의 경우는 흡착표면에서 수용액으로의 물질 전달이었다. TOC분석을 통해 계면활성제를 포함한 거의 모든 기질이 분해됨을 알 수 있었다. pH 변화는 phenanthrene이 산 작용기를 가지는 중간산물로 분해됨을 나타내었다.

• 한국물환경학회지
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• 제23권5호
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• pp.689-696
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• 2007

Kinetic analysis was important to develope the biological nutrient removal process effectively. In this research, anoxic-anaerobic-aerobic system was operated to investigate kinetic behavior on the nutrient removal reaction. Nitrification and denitrification were important microbiological reactions of nitrogen. The kinetics of organic removal and nitrification reaction have been investigated based on a Monod-type expression involving two growth limiting substrates : TKN for nitrification and COD for organic removal reaction. The kinetic constans and yield coefficients were evaluated for both these reactions. Experiments were conducted to determine the biological kinetic coefficients and the removal efficiencies of COD and TKN at five different MLSS concentrations of 5000, 4200, 3300, 2600, and 1900 mg/L for synthetic wastewater. Mathematical equations were presented to permit complete evaluation of the this system. Kinetic behaviors for the organic removal and nitrification reaction were examined by the determined kinetic coefficient and the assumed operation condition and the predicted model formulae using kinetic approach. The conclusions derived from this experimental research were as follows : 1. Biological kinetic coefficients were Y=0.563, $k_d=0.054(day^{-1})$, $K_S=49.16(mg/L)$, $k=2.045(day^{-1})$ for the removal of COD and $Y_N=0.024$, $k_{dN}=0.0063(day^{-1})$, $K_{SN}=3.21(mg/L)$, $k_N=31.4(day^{-1})$ for the removal of TKN respectively. 2. The predicted kinetic model formulae could determine the predicted concentration of the activated sludge and nitrifier, investigate the distribution rate of input carbon and nitrogen in relation to the solid retention time (SRT).

• 한국물환경학회지
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• 제25권5호
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• pp.674-681
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• 2009

Characteristics of organic matters (OM) in wastewater and the removal efficiencies were investigated using the influent and the effluent samples collected from 21 wastewater treatment plants. The OM characteristics investigated included biodegradability, humic content, specific UV absorbance (SUVA), the distribution percentage of refractory OM (R-OM), and synchronous fluorescence spectra. The types of wastewater (sewage, livestock waste/night soils, industrial waste) were easily distinguished by comparing the synchronous fluorescence spectra of the influent wastewater. The prominent peak of protein-like fluorescence (PLF) was observed for livestock waste/night soils whereas sewage exhibited a unique fluorescence peak at a wavelength of 370 nm. Irrespective of the wastewater types, the distribution percentage of R-OM increased from the influent to the effluent. Livestock waste/night soils showed the highest removal efficiency among all the three types of wastewater. There was no statistical difference of the removal efficiency between a traditional activated sludge and biological advanced treatment processes. Removal efficiency based on dissolved organic carbon DOC presented good correlations with the distribution percentage of R-OM and fulvic-like fluorescence (FLF) of the influent. The prediction for DOC removal efficiency was improved by using multiple regression analyses based on some selected OM characteristics and mixed liquid suspended solid (MLSS).

• 한국자기학회지
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• 제3권3호
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• pp.241-246
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• 1993

본 연구에서는 습식법에 의해 얻어진 초미립 마그네타이트 표면에 포화지방산이온($C_{9}~C_{18}$)을 화학흡착시키고, 그 위에 SDBS로서 물리흡착층을 형성시켜 수상자성유체를 제조하였다. 마그네타이트 27 g에 대해서 Lauric acid의 첨가량 $2.66{\times}10^{-2}mol$ 이상, SDBS 첨가량 5g 이상에서 수상자성유체의 분산율이 85% 이상 유지되었다. 고체함량이 0.05 g/cc에서 0.4 g/cc로 증가함에 따라 수상자성유체의 자화값은 2.07 eum/g에서 9.31 eum/g으로 증가하였으며, 점도는 1.20 cp에서 3.95 cp로 증가하였다. 1N-HCI 및 1N-NaOH를 사용하여 수상자성유체의 pH 변화에 따른 분산특성을 조사한 결과 pH 3.1~11.1의 영역에서 안정한 분산특성을 나타내었다. 합성마그네타이트 주위에 포화지방산($C_{9}~C_{18}$)을 제1계면활성제로 사용하여 수상자성유체를 제조한 결과, 탄소길이가 증가함에 따라 분산율은 향상되었으나 다량의 scum이 발생하였다.

• 한국세라믹학회지
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• 제41권2호
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• pp.118-124
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• 2004

탄소환원질화법에 의해 합성된 질화알루미늄의 물성은 출발물질의 종류, 액상$.$기상 반응물질의 양, 분위기 그리고 합성온도에 따라서 많은 차이를 나타내었다 질화알루미늄 합성을 위하여 Al원으로는 $\alpha$-A1$_2$O$_3$를 사용하였고 환원제로는 카본 블랙을 사용하였으며, 기상반응을 유도하기 위하여 AlF$_3$를 사용하여 고순도 질소분위기에서 실험을 행하였다. 또한 액상반응 시 미세구조상의 변화를 확인하기 위하여 금속 알루미늄을 첨가하여 실험을 행하였다. 질화알루미늄이 생성과 침상형 휘스커상의 형상은 1$600^{\circ}C$의 온도에서 가장 잘 나타났으며 열처리 온도의 상승은 오히려 휘스커상의 형성을 방해하고 있음을 보여주었다. 침상형 휘스커의 합성에 가장 큰 영향을 주는 것은 기상반응을 일으키는 AlF$_3$ 첨가이며, AlF$_3$의 첨가량이 증가함에 따라 침상형 휘스커상을 확인하였다. 액상반응을 위한 금속 알루미늄 첨가는 전체의 15wt%까지는 침상형 휘스커가 증가하고 있음을 나타내었으나 l5wt% 이상으로 첨가하는 경우 오히려 휘스커가 감소하는 것으로 나타났다.