• Transactions of the Korean hydrogen and new energy society
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• v.16 no.4
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• pp.307-314
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• 2005

In this work, a static volumetric method was experimentally implemented to measure the adsorption isotherm of hydrogen and methane by the activated carbon. The equilibrium data of stationary phase and mobile phase were correlated into the Langmuir, Freundlich, Langmuir-Freundlich, and Toth isotherms, respectively. In addition, the comparison between prediction and experimental data was made. By a nonlinear regression analysis, the experimental parameters in the equilibrium isotherms were estimated and compared. Then, the linear and quadratic equations for pressure and temperature to adsorption amounts were expressed. The adsorption amounts were increased with the pressure increase and the temperature decrease.

• Bulletin of the Korean Chemical Society
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• v.3 no.4
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• pp.133-139
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• 1982

It has been presumed that the molten sulfur above $159^{\circ}C$ consists of an equilibrium mixture of $S_8$ rings and $S_x$ polymers where the number average degree of polymerization, P, is large. But it is known that admixture of halogens with liquid sulfur greatly reduce the viscosity. Constructing a new equilibrium equation, it is possible to evaluate the viscosity when halogens are added to liquid sulfur. Calculated viscosity is in good agreement with experimental values. Using the proposed model, the thermodynamic properties of liquid sulfur are also calculated over a wide range of temperature which the sulfur exists as the polymer.

• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.127-130
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• 2015

In this study, the adsorption equilibria of acetic acid on activated carbon were investigated at the temperatures of 313.15 K and 323.15 K. The obtained adsorption data were then fitted by Langmuir, Bi-Langmuir, and Freundlich models, in which the relevant model parameters were determined by minimizing the sum of the squares of deviations between experimental data and calculated values. The comparison results revealed that Bi-Langmuir model could account for the adsorption equilibrium data of acetic acid with the highest accuracy among the three adsorption models considered.

• Advances in environmental research
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• v.4 no.2
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• pp.119-133
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• 2015

Water pollution means that the physical, chemical and biological properties of water are changing. In this study, adsorption was chosen as the treatment method because it is an eco-friendly and low cost approach. Magnetite is a magnetic material that can synthesize chemical precipitation. Magnetite was used for the removal of copper in artificial water samples. For this purpose, metal removal from water dependent on the pH, initial concentration of metal, amount of adsorbent and effect of sorption time were investigated. Magnetite was characterized using XRD, SEM and particle size distribution. The copper ions were determined by atomic absorption spectrometry. The adsorption of copper on the magnetite was studied in a batch process, with different aqueous solutions of Cu (II) at concentrations ranging from 10 to $50mg\;l^{-1}$. Optimum conditions for using magnetite were found to be concentration of $10mg\;L^{-1}$, pH: 4.5, contact time: 40 min. Optimum adsorbent was found to be 0.3 gr. Furthermore, adsorption isotherm data were analyzed using the Langmuir and Freundlich equations. The adsorption data fitted well with the Freundlich ($r^2=0.9701$) and Langmuir isotherm ($r^2=0.9711$) equations. Kinetic and equilibrium aspects of the adsorption process were studied. The time-dependent Cu (II) adsorption data were described well by a pseudo-second-order kinetic model.

• Korea-Australia Rheology Journal
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• v.11 no.4
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• pp.287-291
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• 1999

The tube model theory of entangled polymer presumes that the polymer chain holds its equilibrium contour length under certain conditions of flow; at times longer than a certain characteristic time, ${\tau}_k$, in the stress relaxation process following any flow history; in steady flow of rates smaller than ${{\tau}_k}^{-1}$; etc. Rheological phenomena associated with this presumption are discussed.

• Korean Chemical Engineering Research
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• v.55 no.4
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• pp.574-577
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• 2017

In Indonesia, vetiver oil is one commodity that plays an important role in the country's foreign exchange earnings. Currently, the extraction of essential oil from vetiver still uses conventional methods. Therefore, the aim of this study was to know and verify the kinetics and mechanism of microwave hydrodistillation of vetiver based on two models. In this study, microwave hydrodistillation was used to extract essential oils from vetiver. The extraction was carried out in nine extraction cycles of 20 min to 3 hours. The rate constant, the equilibrium extraction capacity, and the initial extraction rate were calculated using the two models. Kinetics of oil extraction from vetiver by microwave hydrodistillation proved that the extraction process was based on the second-order extraction model. The second-order model was satisfactorily applied, with high coefficients of correlation ($R^2=0.9427$), showing that it well described the process.

• Journal of the Korean Chemical Society
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• v.62 no.4
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• pp.279-287
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• 2018

In this study, we analyzed the explanations and examples of Brønsted-Lowry model in Chemistry I and Chemistry II textbooks of the 2009 revised curriculum. In particular, the definition of the Brønsted-Lowry model, the examples, and the content of experiments were analyzed by the process perspective of chemical equilibrium, emergent process. The analyzed textbooks were 4 kinds of Chemistry I textbooks and 4 kinds of Chemistry II textbooks in 2009 revision curriculum. As a result, Chemical I textbooks did not adequately show the chemical equilibrium viewpoint when explaining the Brønsted-Lowry model. In the Chemistry II textbooks, the examples of Brønsted-Lowry model were not present emergent process viewpoint, and those were described as sequential viewpoint of Arrhenius model. In addition, examples of experiments to demonstrate the Brønsted-Lowry model of Chemistry II textbooks were insufficient. The experimental examples related to the definition of acid bases were at the level of classification by the color change of indicators. The experimental examples for explaining the strength of acid and base were to compare current intensity or amount of hydrogen gas generated from the reaction with metal. In addition, all textbooks presented the state of aqueous solution when describing the Brønsted-Lowry model, causing problems with differentiation from the Arrhenius model. Therefore, it is necessary to develop examples of experiments to help students understand Brønsted-Lowry model by presenting acid and base reaction in the non-aqueous solution state.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.109-112
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• 2007

In this paper, a mathematical modeling was developed to simulate 1kW class air cooled Polymer Electrolyte Membrane Fuel Cell(PEMFC) system. The proposed modeling was conducted under SIMULINK based environment. The model ing was developed based on the thermodynamic and chemical equilibrium. The objective is to design and implement the entire fuel cell system model ing including the system controller modeling. The fuel cell process and the control system modeling should have to be connected with each other simultaneously， therefore the two types of modeling influences each other when the system simulator run. The fuel cell modeling libraries are simulated using the SIMULINK under the thermodynamic and chemical equilibrium base. The PID controller application was designed and developed to test the process modeling and verify it. This the prototype development of the fuel cell system to design and test more complicate fuel cell systems, like the residential power generation system. The simulation results was compared to the real PEMFC system performance. We have achieved the reasonable accordance with the Lab test and the simulation results.

• Journal of Environmental Science International
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• v.24 no.3
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• pp.267-274
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• 2015

The feasibility of PS-D2EHPA/TBP beads prepared by immobilizing two extractants D2EHPA and TBP in polysulfone to remove Sr(II) from aqueous solution was investigated in batch system. Batch experiments were carried out to study equilibrium isotherms, kinetics, and thermodynamics. Equilibrium data were fitted using Langmuir, Freundlich, Redlich-Peterson, and Dubinin-Radushkevich equation models at temperatures of 298 K, 313 K, and 328 K. The removal capacity of Sr(II) by PS-D2EHPA/TBP beads obtained from Langmuir model was 2.41 mg/g at 298 K. The experimental data were well represented by pseudo-second-order model. The removal process of Sr(II) by PS-D2EHPA/TBP beads prepared in this study was found to be feasible, endothermic, and spontaneous.

• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.3013-3016
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• 2010