• Proceedings of the Korean Environmental Sciences Society Conference
• /
• 2006.11a
• /
• pp.353-356
• /
• 2006

펜톤-유사 반응의 최척 철 입자 양과 $H_2O_2$ 주입 량은 각각 25 g/L, 60 mmol로 나타났고, 광-펜톤-유사 반응의 최적 철 입자 양과 $H_2O_2$ 양은 각각 0.25 g/L 와 0.625 mmol로 나타나 철 입자 양은 100배, $H_2O_2$ 양은 96배 차이나 펜톤-유사 반응의 경우 다량의 철 입자와 $H_2O_2$ 소비로 인해 RhB의 탈색반응에는 적절하지 않은 것으로 나타났다. 그러나 UV를 함께 적용한 광-펜톤-유사 반응의 경우 철 입자 양과 $H_2O_2$ 양이 적어 적절한 것으로 사료되었다. RhB의 완전한 탈색을 위해서는 적절한 UV 등 전력이 필요하다고 사료되었다.

• 전기의세계
• /
• v.41 no.6
• /
• pp.7-11
• /
• 1992

연료전지는 연료가 가진 화학에너지를 전기화학반응에 의해 직접 전기에너지로 변환시키는 발전방식으로 에너지 변환효율이 높고 환경공해가 적어 도시부근이나 도심지 건물내 설치할 수 있으므로 전력계통운용이 용이하여 장래 화력발전 대체용이나 열병합발전용으로 유효하게 사용될 수 있는 등의 장점이 많아 국내의 개발이 활발이 진행되고 있다. 연료전지는 반응물질을 전지내에 저장헤 두는 1차전지(건전지등)나 2차전지(축전지)와는 달리 반응물질이 외부로부터 공급되는한 발전할 수 있으며 단위전지의 내부구조는 일반전지와 유사하나 에너지저장능력이 없는 발전장치이다.

• Proceedings of the Korea Society for Simulation Conference
• /
• 2004.05a
• /
• pp.41-47
• /
• 2004

중심합성계획(central composite design: ccd)은 반응 표면이 곡면적인 특성을 나타낼때 반응 공간을 추정하기 위해 사용되는 실험계획이다. 반응공간이 2차 회귀모형으로 나타나는 경우에 반응곡면의 변화량을 알기 위해서는 변수의 수준이 3이상이 되어야하는데 ccd는 적은 횟수의 실험으로 곡면을 효과적으로 추정하기 위해 2$^{k}$ 요인실험에 추가적으로 중심점(central point)과 축점(axial point)을 표본점에 포함시키는 계획이다. 본 연구에서는 시뮬레이션 실험에서 반응변수가 2차 회귀모형으로 근사되는 경우에 cod를 이용하여 관심 성과치의 반응표면을 추정하고자 한다. 일반적인 실험에서와는 달리 시뮬레이션 실험에서는 두개의 표본점(인자 수준의 조합)에서 분석자가 공통 난수계열(common random number series)을 부여하여 시뮬레이션 시스템 요소의 변화과정을 유사하게 통제할 수 있다. 일반적으로 공통난수법(common random number method)에 의해 얻어지는 두 표본점에서의 반응변수는 서로 양의 상관관계를 가지며 대조 난수(antithetic random number)에 의한 두 반응변수는 음의 상관성을 가지는 것으로 알려졌다. 본 연구는 ccd의 표본점에 공통난수와 대조난수 법을 이용하여 회귀모형의 파라미터를 효과적으로 추정하는 방법을 조사하고 이를 (s, S) 재고관리 모형에 적용하여 그 효율성을 평가하고자 한다.

• Journal of the Korean GEO-environmental Society
• /
• v.11 no.1
• /
• pp.45-51
• /
• 2010

Cadmium (Cd) adsorption by the activated carbon containing hydroxyapatite (HAP) was investigated. Cd adsorption with different HAP mass ranged from 10% to 30%. With more HAP, more Cd was adsorbed. These results suggest that the higher HAP dose causes an increase of the ion exchange potential in HAP sorbent. Kinetics and equilibrium studies were investigated in series of batch adsorption experiments. Langmuir and Freundlich isotherm models were fit to the equilibrium data and Cd adsorption on HAP sorbent were found to follow the Freundlich isotherm model well in the initial adsorbate concentration range. The simple kinetic model, the pseudo first order kinetic model and the pseudo second order kinetic model, were used to investigate the adsorption. The adsorption reaction of Cd followed the pseudo second order kinetic model, and the adsorption pseudo second order kinetic constants ($k_2$) increased with increasing initial HAP amounts onto activated carbon. Also, intraparticle diffusion model was used to investigate the adsorption mechanism between adsorbate and adsorbent in the aqueous phase. Surface adsorption reaction and intraparticle diffusion occur simultaneously Cd adsorption mechanism from aqueous phase in this study.

• Resources Recycling
• /
• v.25 no.4
• /
• pp.60-67
• /
• 2016

This study was conducted to establish the adsorption-desorption mechanism and the optimum condition of chromatographic operation for separations of heavy rare earth elements (Gd, Tb, Dy) using a p507-containing resin. By employing Langmuir and Freundlich isotherm together with pseudo first and second order kinetics, absorption-desorption reaction mechanism was investigated. Langmuir and Freundlich isotherm was applied under assumption that adsorption reaction occurs in form of monolayer, and because the result was identical to the assumption, now we know adsorption of heavy rare earth elements occurs in form of monolayer. Concerning the pseudo first and second order kinetic, the pseudo second order seemed to be more suitable to represent heavy rare earth element adsorption mechanism. By using the extraction chromatography to separate heavy rare earth elements, ${\alpha}^{Tb}_{Gd}=1.24$, and ${\alpha}^{Dy}_{Tb}=1.03$ were confirmed in eluent HCl 0.25 M which indicates almost perfect separations of three elements. Furthermore, as concentrations of eluent became higher, the resolution value decreased and the elution area got shortened.

• Journal of the Korean Chemical Society
• /
• v.22 no.5
• /
• pp.281-288
• /
• 1978

Pseudo-first order rate constants $k_{obs}$ were determined for the reactions of naphthalenesulfonyl chlorides (1-NSC and 2-NSC) and anilines. The second order rate constant $k_2$ and third order catalytic $k_3$ were then determined from $k_{obs}$. For 1-NSC peri-hydrogen effect was observed. The large Brønsted ${\beta}$ and large negative slopes ${\rho}$ for the Hammett plots were obtained. These results with the unsually low values of activation parameters were consistent with the $S_AN$-elimination mechanism, but these can be equally well interpreted with the associative $S_N2$mechanism.

• Journal of Korea Soil Environment Society
• /
• v.4 no.1
• /
• pp.97-108
• /
• 1999

Reduction 2, 4, 6-trinitrotoluene by zero valent iron was studied in a batch reactor under anoxic conditions. Results showed that the removal of trinitrotoluene (TNT)followed a pseudo-first order reaction and the rate was linearly dependent on the available reactive surfau area of the zero valent iron surface area, resulting a rate constant of 0.0981min$^{1}m$$^{-2}m$. High concentrations of the final product, presumably triaminotoluene which needs to be treated by other means, accumulated in the solution. However , little amount of TAT was extracted from the metal surface by using acetonitrile or phosphate buffered water (pH 7.0). Other common major intermediate in biological TNT degradation, a group of aminodinitrotoluenes, was not detected in the solution. Therefore, it is postulated that the reduction of nitro group by $Fe^0$ occurs simultaneously in all three positions and a TNT reduction model by zero valent iron was suggested.

• Journal of the Korean Chemical Society
• /
• v.48 no.5
• /
• pp.461-466
• /
• 2004

Kinetics for the nucleophiles have been studied under high vacuum and high pressures in various temperatures. Pseudo-first order rate constants, second order rate constants, thermodynamic parameters and Hammett ${\rho}$-values are determined. The values of ${\Delta}V^{\neq},\;{\Delta}{\beta}^{\neq}\;and\;{\Delta}S^{\neq}$are all negative. The Hammett r-values are negative for the nucleophile (${\rho}$x) over the pressure range studied. The results of kinetic studies for pressure and nucleophilet show that these reactions proceed in typical $S_N2$ reaction mechanism and change of mechanism.

• The Journal of the Korea Contents Association
• /
• v.9 no.10
• /
• pp.444-450
• /
• 2009

We have investigated biosorption kinetics and equilibrium of $Pb^2+$ and $Cr^2+$ using waste sludge, and separation efficiency of waste sludge by dissolved air flotation was evaluated in the various A/S ratio. The biosorption capacity and contact time were shown as a simulation of biosorption equilibrium and kinetics models. Biosorption equilibrium of the $Pb^2+$ and $Cr^2+$ onto the waste sludge could be fitted by the Langmuir, Freundlich, Redlich-Peterson, and Koble-Corrigan equation. The kinetics could be fitted by a pseudo-second-order rate equation more than a pseudo-first-order rate equation. The separation efficiency of waste sludge using DAF was kept above 90%.

• Journal of the Korean Chemical Society
• /
• v.36 no.2
• /
• pp.174-179
• /
• 1992

Reaction of aniline and iodine in$CHCl_3,\;CH_2Cl_2 : CHCl_3$(1 : 1), and $CH_2Cl_2$ has been studied kinetically by using conductivity method, Pseudo first-order rate constants ($k_{obs}$) and second-order rate constants ($k_{obs}$/[aniline]) are dependent on the aniline concentration. Second-order rate constants obtained were increased with increasing aniline concentration. We analysed these results on the basis of formation of charge transfer complex as reaction intermediate. From the construction of react ion scheme and derivation of rate equation, we calculated equilibrium constants and activation parameters for the formation and transformation of charge transfer complex. The equilibrium constants were decreased by an increase in the dielectric constant of the solvent and the value is 1.7-3.7$M^{-1}$. The rate of transformation are markedly affected by the solvent polarity. ${\Delta}H^{\neq}$ is about 14.2kJ/mol, and ${\Delta}S^{\neq}$ is large negative value of -243J/mol K.