• Title/Summary/Keyword: kinetics

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Kinetics and Hydrolysis Mechanism of Herbicidal N-(2,6-dimethoxypyrimidin-2-yl)aminocarbonyl-2-(1-hyd roxy-2-fluoroethyl)benzenesulfonamide Derivatives (제초성, N-(2,6-dimethoxypyrimidin-2-yl)aminocarbonyl-2-치환(Z)-6-(1-hyd roxy-2-fluoroethyl)benzenesulfonamide 유도체의 가수분해 반응 메카니즘)

  • Lee, Chan-Bog;Ryu, Jae-Wook;Kim, Dae-Whang;Sung, Nack-Do
    • Applied Biological Chemistry
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    • v.38 no.5
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    • pp.455-462
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    • 1995
  • The new six herbicidal N-[(pyrimidin-2-yl)aminocarbonyl]-2-substituted-6-(1-hydroxy-2-fluoroethyl)benzenesulfonamide derivatives(S) were synthesized and rate constants for the hydrolysis of thier in the range of pH $1.0{\sim}10.0$ have been studied in 15%(v/v) aqueous acetonitrile solution at $45^{\circ}C$. From the basis of the results, pH-effect, solvent effect, ortho-substituent effect, thermodynamic parameters(${\Delta}H^{\neq}$ & ${\Delta}S^{\neq}$), pKa constant(4.80), rate equation, analysis of hydrolysis products(2-(1-hydroxy-2-fluoroethyl)benzenesulfonamide & 4,6-dimethoxyaminopyrimidine), it may be concluded that the general acid catalyzed hydrolysis through $A-S_E2$ mechanism and specific acid catalyzed hydrolysis through A-2 type(or $A_{AC}2$) mechanism proceeds via conjugate acid($SH^+$) and tetrahedral intermediate(I) below pH 8.0, whereas, above pH 9.0, the general base catalyzed hydrolysis by water molecules(B) through $(E_1)_{anion}$ mechanism proceeds via conjugate base(CB). In the range between $pH\;7.0{\sim}pH\;9.0$, these two reactions occur competitively.

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Removal of Heavy Metals from Aqueous Solution by a Column Packed with Peat-Humin (Peat-Humin 충전 칼럼을 이용한 수용액 중의 중금속 제거)

  • Shin, Hyun-Snag;Lee, Chang-Hoon;Lee, Yo-Snag;Kang, Ki-Hoon
    • Journal of Korean Society of Environmental Engineers
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    • v.27 no.5
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    • pp.535-541
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    • 2005
  • Peat humin(p-Humin) extracted from Canadian Sphagnum peat moss was packed in a column and removal of heavy metal ions such as Cd, Cu and Pb from aqueous solution under flow conditions was studied. The metal ions were removed not only from single-element solutions but also from a multi-metal solution. Column kinetics for metal removal were described by the Thomas model. For single-component metal solutions, the maximum adsorption capacities of the p-Humin for Pb, Cu and Cd were 138.8, 44.66 and 41.61 mg/g, respectively. The results of multi-component competitive adsorption showed that adsorption affinity was in the order of Pb $\gg$ Cu > Cd. The adsorbed metal ions were easily deserted from the p-Humin with 0.05 N $HNO_3$ solution. It is apparent that 95% of the heavy metal ions were recovered from the saturated column. This investigation provides possibility to clean up heavy-metal contaminated waste waters by using the natural biomass, p-Humin as an environmentally friendly and cost-effective new biosorbents.

Effects of Membrane Size and Organic Matter on Membrane Fouling (천연유기물질의 특성과 막의 종류에 따른 막오염 메카니즘 분석)

  • Jung, Chul-Woo;Son, Hee-Jong
    • Journal of Korean Society of Environmental Engineers
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    • v.28 no.10
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    • pp.1046-1054
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    • 2006
  • The raw water DOC contained 39.3% of hydrophilics, 42.9% of hydriophobic, and 17.8% of transphilic. The hydrophobic fraction in this raw water was mostly fulvic acid. Fulvic acid comprised of 62% and the rest was humic acid(38%). There was more carboxylic acid functional group(64%) than phenolic group(36%). HPI-N and HPI-C comprised of 17% and 22% in the hydrophilic portion, respectively. The fouling mechanisms on the membrane surface and into its porous structure were analyzed in terms of several kinetic models. In order to analyze the fouling kinetics, the various kinetic models described in this paper were used to fit the experimental results. The kinetic models and kinetic constants obtained for each operation condition. The permeate flux was rapidly declined by simultaneous pore blocking and cake formation. Also, the permeate flux declined with decreasing internal pore size resulted from organic deposition into the membrane pore. The results of the membrane fouling test using UF membrane according to NOM fractions. HPI-N caused more fouling than HPI-C. Humic acid caused more fouling than fulvic acid probably due to higher adsorption capacity. Since humic acid has higher adsorption capacity than fulvic acid, it would be more adsorbed onto the membrane pores.

Structural and Kinetic Characteristics of 1,4-Dioxane-Degrading Bacterial Consortia Containing the Phylum TM7

  • Nam, Ji-Hyun;Ventura, Jey-R S.;Yeom, Ick Tae;Lee, Yongwoo;Jahng, Deokjin
    • Journal of Microbiology and Biotechnology
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    • v.26 no.11
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    • pp.1951-1964
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    • 2016
  • 1,4-Dioxane-degrading bacterial consortia were enriched from forest soil (FS) and activated sludge (AS) using a defined medium containing 1,4-dioxane as the sole carbon source. These two enrichments cultures appeared to have inducible tetrahydrofuran/dioxane and propane degradation enzymes. According to qPCR results on the 16S rRNA and soluble di-iron monooxygenase genes, the relative abundances of 1,4-dioxane-degrading bacteria to total bacteria in FS and AS were 29.4% and 57.8%, respectively. For FS, the cell growth yields (Y), maximum specific degradation rate ($V_{max}$), and half-saturation concentration ($K_m$) were 0.58 mg-protein/mg-dioxane, $0.037mg-dioxane/mg-protein{\cdot}h$, and 93.9 mg/l, respectively. For AS, Y, $V_{max}$, and $K_m$ were 0.34 mg-protein/mg-dioxane, $0.078mg-dioxane/mg-protein{\cdot}h$, and 181.3 mg/l, respectively. These kinetics data of FS and AS were similar to previously reported values. Based on bacterial community analysis on 16S rRNA gene sequences of the two enrichment cultures, the FS consortium was identified to contain 38.3% of Mycobacterium and 10.6% of Afipia, similar to previously reported literature. Meanwhile, 49.5% of the AS consortium belonged to the candidate division TM7, which has never been reported to be involved in 1,4-dioxane biodegradation. However, recent studies suggested that TM7 bacteria were associated with degradation of non-biodegradable and hazardous materials. Therefore, our results showed that previously unknown 1,4-dioxane-degrading bacteria might play an important role in enriched AS. Although the metabolic capability and ecophysiological significance of the predominant TM7 bacteria in AS enrichment culture remain unclear, our data reveal hidden characteristics of the TM7 phylum and provide a perspective for studying this previously uncultured phylotype.

Effects of Disinfectant Concentration, pH, Temperature, Ammonia, and Suspended Solids on the Chlorine Disinfection of Combined Sewer Overflow (소독제 농도, pH, 온도, 암모니아 농도, 부유물질이 강우 월류수 염소 소독에 미치는 영향)

  • Kim, Sang-Hyoun
    • Journal of Korean Society of Environmental Engineers
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    • v.36 no.10
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    • pp.685-690
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    • 2014
  • The treatment of combined sewer overflow (CSO) is one of potential concerns in domestic wastewater treatment in Korea due to the pre-announce of CSO regulations. This work investigated the effects of disinfectant (NaOCl) concentration (0.11 to 4.0 mg $Cl_2/L$), pH (6.5 to 8.0), temperature (15 to $25^{\circ}C$), ammonia (10 to 41 mg N/L), and suspended solids (91 to 271 mg SS/L) on the chlorine disinfection of CSO. The effect of NaOCl concentration on the pseudo-$1^{st}$ order reaction rate for total coliform inactivation was described well with a saturation-type model with the half-velocity constant of 1.212 mg/L. The total coliform inactivation reaction rate decreased with SS and pH, and increased with temperature. Ammonia in the examined range did not affect the disinfection kinetics. A chlorine contact tank with the injection chlorine level of 1 mg $Cl_2/L$ and the hydraulic retention time of 1.25 min is estimated to reduce total coliform from $1{\times}10^5MPN/mL$ to 1,000 MPN/mL at 271 mg SS/L, $15^{\circ}C$, and pH 8.0. Chlorine would be a proper option for the disinfection of CSO.

Evaluation of Removal Characteristics of Taste and Odor Causing Compounds using Meso-Porous Absorbent (메조공극 흡착제를 이용한 상수원수내 맛·냄새 유발물질 제거특성 평가)

  • Kim, Jong-Doo;Park, Chul-Hwi;Yun, Yeo-Bog;Lee, Dae-Sung;Kim, Hyo-Jeon;Kang, Seok-Tae
    • Journal of Korean Society of Environmental Engineers
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    • v.39 no.1
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    • pp.26-33
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    • 2017
  • The objective of this study was to evaluate the characteristic of adsorption by using a meso-porous adsorbent (MPA), and investigate the removal efficiency of geosmin which taste and odor causing compounds in drinking water supplies through batch test. The results for the adsorption isotherm was analyzed by using the Langmuir equation and Freundlich equation, generally being applied. And the study showed that the both Langmuir and Freundlich equation explains the results better. Both of pseudo-first-order model and pseudo-second-order model were respectively applied for evaluation of kinetic sorption property of geosmin onto MPA. The adsorption experiment results using MPA showed that maximum adsorption capacity of MPA was lower 7 times than that of GAC, and adsorption rate of MPA was faster 11 times than that of GAC, on the basis of pseudo-first-order model. Therefore, it was determined that MPA was effectively able to remove geosmin in drinking water supplies in short EBCT condition, but regeneration cycle in MAP process was shorter than that in conventional process.

The Non-Enzymatic Browning and Shelf-Life of Dried Shrimp during Storage under Fluctuating Temperature Conditions (건조 새우의 변온저장중 갈변 및 Shelf-life)

  • KIM Yong-Ju;KIM Mu-Nam;KANG Moon-Sun;CHO Young-Je;KIM Yuck-Yong;CHUN Soon Sil
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.27 no.1
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    • pp.7-12
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    • 1994
  • The kinetics of browning reaction of dried shrimp powder samples were investigated during storage. The temperature conditions of the ding process were $25^{\circ}C\;and\;45^{\circ}C$, and the samples were stored at water activity ($a_w$) of 0.33, 0.44, 0.52, 0.65 and temperatures of $35^{\circ}C,\;45^{\circ}C,\;55^{\circ}C$ and temperature fluctuations between $33^{\circ}C\;and\;55^{\circ}C$. When the shrimp was dried at $25^{\circ}C$ the activation energies obtained from the Arrhenius plot ranged from 13.57 to 14.33 kcal/mol. From these energies of activation, the $Q_{10}$ values at $25^{\circ}C$ showed 1.93 to 2.00. In the case of drying at $45^{\circ}C$ the activation energies were $13.12{\sim}13.61\;kcal/mol$ and $Q_{10}$ values were $1.89{\sim}1.93$, respectively. In addition, a storage study under square-wave fluctuating temperature conditions was carried out by varying the shrimp sample temperature between $35^{\circ}C\;and\;55^{\circ}C$ within 7 days regular fluctuation cycle. The data obtained from the fluctuating temperature storage study will be used in the prediction of shelf-lives. The shelf-lives assessed at $25^{\circ}C$ from the accelerated shelf-life tests ranged from 4 days at aw 0.65 to 139 days at aw 0.33.

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Effect of Carbon Tetrachloride on the Changes of Xanthine Oxidase Activity in Rate Previously Fed Low or High Protein Diet (식이성 단백질 함량에 따른 흰쥐에 사염화탄소 투여가 Xanthine Oxidase활성에 미치는 영향)

  • 윤종국;이상일;신중규
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.20 no.6
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    • pp.527-537
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    • 1991
  • To evaluate an effect of liver xanthine oxidase on the induction of liver damage, carbon tetrachloride (CCl4) was intraperitoneally injected twice at 0.1ml/100g body weight to the rate fed a low (LP)or high protein diet(HP) while the control group fed LP or HP received only olive oil. The changing rate of liver xanthine oxidas activity was compared with that of a free radical generating enzyme, liver aniline hydroxylase and a scavenging enzyme, glutathions S-transferase activity between the rate fed a LP and those fed HP, and the two groups treated with CCl4. Concomitantly, the degree of liver damage which could be considered as the paramete for CCl4 metabolism in case of CCl4-intoxicated animal was observed in the present experimental conditions and the effect of allopurinol, xanthine oxidase inhibitor, on the CCl4-toxicity of rate liver was alos demostrated. On the other hand, the comparative effect of actinomycin D on the liver and serum xanthine oxidase of CCl4-treated rats fed HP with that of those fed LP and the kinetics of purifed liver enzyme from the liver of CCl4-treated rats fed HP was also compared with that of those fed LP to clarify the differences of xanthine oxidase activity between two groups. The increasing rate of liver weigth/body wt, serum levels of ALT and the decreasing rate of hepatic ALT activity and protein contents to each control group were higher in CCl4-treated rats fed HP than those fed LP. Under the animal models as indentified by the present data herein, the liver xanthine oxidase activity was higher in CCl4-treated rats fed HP than those fed LP, and the control group fed HP also showed the much higher activity xanthine oxidase than that fed LP, whereas there were no differences in the activity of hepatic aniline hydroxylase and glutathions S-transferase between the two group treated with CCl4. Although the hepatic aniline hydroxylase activity was somewhat higher in the rats fed HP than those fed LP, the increasing rate of liver xanthine oxidase to the rats fed LP was higher in those fed HP than that of liver aniline hydroxylase. The degree of liver damage identified such as liver weight and serum ALT activity was less in the CCl4-treated rats pretreated with allopurinol. These results suggest that even a system at which xanthine oxidase acts as well as the drug metabolizing enzyme may influence the acelatin of CCl4 metabolism. In addition, the purified liver xanthine oxidase from CCl4-treated rats fed HP showed decreased Km value when compared to its control group. The Km value of liver xanthine oxidase of CCl4-treated rats fed LP showed a similar Km value with its control group. Furthermore, the decreasing rate of liver and serum xanthine oxidase acitivity in CCl4-treated rats pretreated with actinomycin D to the CCl4-treated rats was higher in rats fed HP than in those fed LP. These results suggest that the inductino of xanthine oxidase in CCl4-treated rats fed HP may be greater than in those fed LP.

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The Kinetics of Non-Enzymatic Browning Reaction in Green Tea During Storage at Different Water Activities and Temperatures (온도와 수분활성을 달리한 녹차 저장중의 비효소적 갈변)

  • Kim, Young-Suk;Jung, Yeon-Hwa;Chun, Soon-Sil;Kim, Mu-Nam
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.17 no.3
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    • pp.226-232
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    • 1988
  • Non-enzymatic browning is a carbohydrate dehydration reaction, accelerated thorough the interaction of amino compounds. Reaction depends on several factors including temperature, reactant concentration, pH, water activity and specific ion concentrations, and result in progressive development of brown pigments in the affected food systems. The present study was designed to utilize a kinetic approach to analyze the effect of temperature and water activity on the browning development in green ten. The green tea was controlled at aw of 0.33, 0.44, 0.52 and 0.65 using saturated salt solutions and then stored at 35,45 and $55^{\circ}C$. Author portion of the sample of which the water activities were controlled in the same manner was stored at 35 and $55^{\circ}C$ alternately with 7 days interval. Simplified kinetic models were used to obtain the various kinetic parameters for browning development in green tea subjected to accelerated shelf-life tests(ASLT). The reaction of browning development was zero order. The activation energies calculated from Arrhenius plot ranged $1.5{\sim}2.4kcal/mole$ and $Q_{10}$ values were between 1.07 and 1.12. These kinetic parameters were then used to predict browning development under the nonsteady storage. Assessed from the parameters the shelf-lives at $25^{\circ}C$, the time to reach 1.02 O.D./g solid at which severe brown color change could be detectable, ranged 57 to 113 days and showed decrease with increase in aw. The predicted shelf-lives at different water activities were a little higher than actual values.

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A Basic Study on Micro-Electric Potential accompanied with Specimen Failure during Uniaxial Compressive Test (일축 압축에 의한 시료 파괴 시 수반되는 미소 전위에 대한 기초 연구)

  • Kim, Jong-Wook;Park, Sam-Gyu;Song, Young-Soo;Sung, Nak-Hun;Kim, Jung-Ho;Cho, Seong-Jun
    • Geophysics and Geophysical Exploration
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    • v.10 no.3
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    • pp.203-210
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    • 2007
  • As a part of basic studies on monitoring of landslides and slope stability using SP measurements, micro-electric potentials of rock samples were measured accompanied with the rock failure by a uniaxial loading test were measured. The measurement system consists of a 8 channel A/D converter with 24 bit resolution, uniaxial loading tester, strain gages and 4 sets of electrode attached to a rock sample. Rock samples of granite, limestone, and sandstone were tested. Also, mortar samples were tested in order to monitor electric-potentials of a uniform sample. Micro-electric potentials were detected in all saturated samples and the strength of them increased as the loading force increased. Sandstone samples showed the largest strength of micro-electric potential and it followed limestone and granite samples, which indicates a positive relationship with porosity of rocks. The mechanism generating these micro-electric potential can be explained in terms of electro-kinetics. In case of dry samples, micro-electric potential could be observed only in sandstone samples, where piezoelectric effect played main role due to high contents of quartz in sandstone samples. We found that biggest micro-electric potentials were observed at the electrodes near the crack surface of rock samples. This is very encouraging result that SP monitoring can be applied to predicting landsliding or to estimate collapsing position combining with monitoring of acoustic emissions.