• Bulletin of the Korean Chemical Society
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• 제28권3호
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• pp.373-378
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• 2007

A micro organism Agrobacterium tumifacient as an immobilized cell on a solid support was presented as a new biosorbent in a simple and sensitive spectrophotometry determination of Ni(II) in various samples using 4-hydroxy benzaldehyde-4-bromophenyl hydrazone as a color developing agent (λmax 497 nm) at pH 4.0 ± 0.2. Beer's law was obeyed over the range of 0.01-0.1 μg L-1. The molar absorptivity and Sandell's sensitivity were 1.285 × 105 L mol-1cm-1 and 0.007245 μg cm-2 respectively. Under these conditions, the preconcentration factor obtained was 82, and the detection limit achieved was 0.05 μg L-1. The detailed study of various interfering ions made the method more sensitive and selective. The recovery of Ni(II) from various samples range from 97.75 to 99.35%. The present method was successfully applied for the determination of Ni(II) in spiked, natural water and alloy samples. The proposed method was compared with reported methods in terms of Student's ‘t'-test and Variance ratio ‘f'-test which indicates that there is no significant difference between proposed and literature method at 95% confidence level.

• 대한화학회지
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• 제26권4호
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• pp.211-217
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• 1982

흑연 표면에 흡착된 Kr분자를 2D기체로 보고 2D비리알상태방정식의 넷째 비리알 계수를 cluster intergral을 이용해서 계산하였으며, 또한 Henry 상수와 둘째 및 셋째 비리알계수도 계산하였다. 그리고 이 상태방정식으로부터 흡착등온곡선을 구하여 실험결과와 비교하여 본 결과 상당히 만족스런 결과를 얻었다. Kr-고체표면 사이의 상호작용 에너지는 Lennard-Jones(12,6)퍼텐셜의 pairwise additivity를 가정하여 구하였으며, 여기에 사용한 파라미터는 ${\varepsilon}_{gs}$/k = 71.1 K, ${\varepsilon}_{gg}$/k = 170 K, ${\sigma}_{gs}$ = 354 pm 및 ${\sigma}_{gg}$ = 368 pm이다.

• Advances in environmental research
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• 제1권4호
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• pp.289-304
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• 2012

Tris (2-methyl-1-aziridinyl) phosphine oxide (MAPO) is extremely poisonous and persistent in aqueous media. An efficient UV/nano$TiO_2$ process was employed for its mineralization in a high duty falling film photo-reactor based on an experimental design scheme that considers interactions between the main variables. The influencing variables and their range were determined with preliminary studies. The results show substrate mineralization to some extent under mild conditions of: T = $30^{\circ}C$, pH = 8.5, $[MAPO]_0=60\;mg\;L^{-1}$ and $[TiO_2]=110\;mg\;L^{-1}$. The relative importance of the influencing parameters were initial pH > temperature > $[MAPO]_0$ > [$TiO_2$]; while the interdependence of all the parameters was significant. Accordingly, a reduced quadratic expression was developed. Meanwhile, mineralization kinetic studies, based on chemical oxygen demand, revealed a power law model with order of 2.6 during process time until 150 min.

• Bulletin of the Korean Chemical Society
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• 제8권2호
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• pp.79-83
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• 1987

The reduction of a series of 1-substituted benzyl-3-cyanoquinolinium ions (p-$cH_3$, H, p-Br, m-F, p-CN) by sodium borohydride has been investigated. In all cases the products from these reactions were found to be 1, 2-dihydroquinolines over 82% yields. Rates of reduction were measured in basic condition and in solvent system consisting of 4 parts of isopropyl alcohol and 1 part of water by volume. Second order rate constants were obtained for these reactions. When the ratio of [$OH^-$] to [$BH_4^-$] becomes large the observed rate constants ($K_{obs}$) decrease by a small factor. Reaction scheme and rate law are discussed. Bronsted ${\alpha}(=\frac{d\;In\;k}{d\;In\;K})$ obtained by using the value of equilibrium constant K, which was obtained previously, was not 0. Instead, a value of 0.36 was obtained which indicated that the reduction by borohydride was structure-dependent according to the Marcus formalism even though the reaction rate was close to the diffusion limit.

• Bulletin of the Korean Chemical Society
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• 제27권2호
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• pp.255-265
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• 2006

The oxidation of hydrazobenzene by molecular oxygen in the polar solvent methanol is catalysed by a Schiff's base complex Co(3MeOsalen) which is a synthetic oxygen carrier. The products are trans-azobenzene and water. The rate of the reaction has been studied spectrophotometrically and the rate law established. A mechanism involving a ternary complex of catalyst, hydrazobenzene and molecular oxygen has been proposed. The kinetic studies show that a ternary complex $CoL{\cdot}H_2AB{\cdot}O_2$ is involved in the rate determining step. The reactions are summarised in a catalytic cycle. The kinetic data suggest that a ternary complex involving Co(3MeOsalen), triphenyl-phosphine and molecular oxygen is catalytically acive species but at higher triphenylphosphine concentrations the catalyst becomes inactive. The destruction of the catalytic activity could be due to the catalyst becoming coordinated with triphenyl phosphine at both z axis sites of the complex e.g. Co (3MeOsalen)$(PPh_3)_2$.

• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.933-940
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• 2012

Recently, it has been shown that quantum coherence appears in energy transfers of various photosynthetic lightharvesting complexes at from cryogenic to even room temperatures. Because the photosynthetic systems are inherently complex, these findings have subsequently interested many researchers in the field of both experiment and theory. From the theoretical part, simplified dynamics or semiclassical approaches have been widely used. In these approaches, the quantum-classical Liouville equation (QCLE) is the fundamental starting point. Toward the semiclassical scheme, approximations are needed to simplify the equations of motion of various degrees of freedom. Here, we have adopted the Poisson bracket mapping equation (PBME) as an approximate form of QCLE and applied it to find the time evolution of the excitation in a photosynthetic complex from marine algae. The benefit of using PBME is its similarity to conventional Hamiltonian dynamics. Through this, we confirmed the coherent population transfer behaviors in short time domain as previously reported with a more accurate but more time-consuming iterative linearized density matrix approach. However, we find that the site populations do not behave according to the Boltzmann law in the long time limit. We also test the effect of adding spurious high frequency vibrations to the spectral density of the bath, and find that their existence does not alter the dynamics to any significant extent as long as the associated reorganization energy is changed not too drastically. This suggests that adopting classical trajectory based ensembles in semiclassical simulations should not influence the coherence dynamics in any practical manner, even though the classical trajectories often yield spurious high frequency vibrational features in the spectral density.

• 농업과학연구
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• 제35권1호
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• pp.53-67
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• 2008

The principle goal of environmentally-friendly agriculture is to maintain and conserve water and agriculture environment including drinking water resources by properly using agricultural materials such as agricultural chemicals, chemical fertilizers, and other agricultural materials according to act 19 of foster law of environmentally-friendly agriculture. To achieve these goals, we have to establish Integrated Nutrient Management(INM) and Integrated Pesticide Management(IPM) which are most important core technologies for environmentally-friendly rice cultivation. However, there are lack of criteria and technology for evaluation category according to soil management and its soil classes to practice an environmentally-friendly agriculture. Therefore, we should eatablish the standards to produce the safe agricultural products based on the soil physical and chemical characteristics which are basic properties of soil to accomplish the principle aims of environmentally-friendly agriculture.

• Bulletin of the Korean Chemical Society
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• 제24권12호
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• pp.1767-1770
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• 2003

A simple, rapid and sensitive spectrophotometric method is herewith proposed for the determination of copper(II) by using diamine-dioxime ligand, meso-3,6,6,9-tetramethyl-4,8-diazaundecane-2,10-dione dioxime or meso-HexaMethyl Propylene Amine Oxime (meso-HMPAO). This method is based on the formation of a stable 1 : 1 red-pink complex between copper(II) and meso-HMPAO in aqueous solution. Absorption measurements were carried at 497 nm, with a molar absorptivity value of 338 L $mol^{-1}\;cm^{-1}$. Beer's law was obeyed over the concentration range of 0.5-370 ${\mu}$g $mL^{-1}$ with a Sandell's sensitivity value of 0.18 ${\mu}$g $cm^{-2}$. The proposed method has been successfully applied for determination of copper(II) in foodstuffs and pharmaceutical samples. The results obtained from this method are comparable with those obtained AAS.

• Bulletin of the Korean Chemical Society
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• 제23권2호
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• pp.291-294
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• 2002

The reactions of triplet oxygen atom with halomethanes as a potential fire extinguisher were studied by a discharge flow-chemiluminescence imaging method. The experiments were carried out under second order conditions. The bimolecular atom-molecule reaction rate constants were determined in terms of the initial rate method. The initial concentration of oxygen atom was also determined under second order rate law instead of the pseudo-first order conditions with $[O(^3P)]_0{\ll}[sample]_0$. The second order conditions were more reliable than pseudo-first order conditions for the determinations of rate constants. The rate constants of the reactions $CF_3I\;+\;O(^3P)$, $CH_3PI\;+\'O(^3P)$, and $CHBrCl_2\;+\;O(^3P)$ were determined to be $5.0\;{\times}\;10^{-12}$ , $1.1\;×\;0^{-11}$ , and $1.9\;{\times}\;10^{-14}cm^3molecule^{-1}s^{-1}$, respectively.

• Bulletin of the Korean Chemical Society
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• 제26권6호
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• pp.943-946
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• 2005

An effective spectrophotometric determination of palladium with 4-(2-pyridylazo)-resorcinol (PAR) using molten naphthalene as a diluent has been studied. A red complex of palladium with PAR is formed at 90 ${^{\circ}C}$. In the range of pH 9.0-11.0, the complex is quantitatively extracted into molten naphthalene. The organic phase is anhydrously dissolved in $CHCl_3$ to be determined spectrophotometrically at 520 nm against the reagent blank. Beer’s law is obeyed over the concentration range of 0.1-2 ${\mu}g{\cdot}mL^{-1}$. The molar absorptivity and Sandell’s sensitivity are 8.0 ${\times}\;10^5\;L{\cdot}mol^{-1}{\cdot}cm^{-}1\;and\;0.49\;{\mu}g{\cdot}cm^{-2}$ respectively. From the results of tolerance limits, it was found that there was no interferences were observed for most of the ions examined and those somewhat high interferences by Co(II), Fe(II) and Bi(III) could be effectively masked by EDTA.