• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.175-183
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• 2008

Adsorption equilibria of the gases $CO_2$, CO, $CH_4$ and $H_2$ and their binary mixtures on Li-X zeolite (UOP) were obtained by static volumetric method in the pressure range of 0 to 20 bar at temperatures of 293.15, 303.15, and 313.15 K. Using the parameter obtained from single-component adsorption isotherm. Multicomponent adsorption equilibra could be predicted and compared with experimental data. Extended Langmuir isotherm, Extended Langmuir-Freundlich isotherm (L-F) and dual-site Langmuir isotherm (DSL) were used to predict the experimental results for binary adsorption equilibria of $H_2/CO_2$, $H_2/CO$, and $H_2/CH_4$ on Li-X Zeolite. Extended Langmuir-Freundlich isotherm predicted equilibria of $CH_4$ and $H_2$ better than any other isotherm. One the other hand DSL isotherm predicted equilibria of $CO_2$ and CO very well.

• Journal of the Korean Electrochemical Society
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• v.9 no.1
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• pp.19-28
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• 2006

The phase-shift method for determining the Langmuir, Frumkin, and Temkin adsorption isotherms ($\theta_H\;vs.\;E$) of H for the cathodic $H_2$ evolution reaction (HER) at a Pt/0.1 M KOH solution interface has been proposed and verified using cyclic voltammetric, differential pulse voltammetric, and electrochemical impedance techniques. At the Pt/0.1 M KOH solution interface, the Langmuir and Temkin adsorption isotherms ($\theta_H\;vs.\;E$), the equilibrium constants ($K_H=2.9X10^{-4}mol^{-1}$ for the Langmuir and $K_H=2.9X10^{-3}\exp(-4.6\theta_H)mol^{-1}$ for the Temkin adsorption isotherm), the interaction parameters (g=0 far the Langmuir and g=4.6 for the Temkin adsorption isotherm), the rate of change of the standard free energy of $\theta_H\;with\;\theta_H$ (r=11.4 kJ $mol^{-1}$ for g=4.6), and the standard free energies (${\Delta}G_{ads}^{\circ}=20.2kJ\;mol^{-1}$ for $k_H=2.9\times10^{-4}mol^{-1}$, i.e., the Langmuir adsorption isotherm, and $16.7<{\Delta}G_\theta^{\circ}<23.6kJ\;mol^{-1}$ for $K_H=2.9\times10^{-3}\exp(-4.6\theta_H)mol^{-1}$ and $0.2<\theta_H<0.8$, i.e., the Temkin adsorption isotherm) of H for the cathodic HER are determined using the phase-shift method. At intermediate values of $\theta_H$, i.e., $0.2<\theta_H<0.8$, the Temkin adsorption isotherm ($\theta_H\;vs.\;E$) corresponding to the Langmuir adsorption isotherm ($\theta_H\;vs.\;E$), and vice versa, is readily determined using the constant conversion factors. The phase-shift method and constant conversion factors are useful and effective for determining the Langmuir, Frumkin, and Temkin adsorption isotherms of intermediates for sequential reactions and related electrode kinetic and thermodynamic data at electrode catalyst interfaces.

• Korean Chemical Engineering Research
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• v.58 no.1
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• pp.127-134
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• 2020

The adsorption characteristics of the major tar compound, acenaphthene, derived from Taxus chinensis by the commercial adsorbent Sylopute were investigated using different parameters such as initial acenaphthene concentration, adsorption temperature, and contact time. Out of Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models, adsorption data were best described by Langmuir isotherm. The adsorption kinetics was evaluated by pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The pseudo-second-order model was found to explain the adsorption kinetics most effectively. Thermodynamic parameters revealed the feasibility, nonspontaneity and exothermic nature of adsorption. In addition, the isosteric heat of adsorption was independent of surface loading indicating the Sylopute used as an energetically homogeneous surface.

• Journal of Korean Society of Water and Wastewater
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• v.34 no.3
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• pp.201-210
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• 2020

2 (Langmuir, Freundlich, Elovich, Temkin, and Dubinin-Radushkevich) and 3 (Sips and Redlich-Peterson)-parameter isotherm models were applied to evaluated for the applicability of adsorption of Cu(II) and/or phosphate isotherm using chitosan bead. Non-linear and linear isotherm adsorption were also compared on each parameter with coefficient of determination (R²). Among 2-parameter isotherms, non-linear Langmuir and Freundlich isotherm showed relatively higher R² and appropriate maximum uptake (q_m) than other isotherm equation although linear Dubinin-Radushkevich obtained highest R². 3-parameter isotherm model demonstrated more reasonable and accuracy results than 2-parmeter isotherm in both non-linear and linear due to the addition of one parameter. The linearization for all of isotherm equation did not increase the applicability of adsorption models when error experiment data was included.

• Journal of the Korean Chemical Society
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• v.62 no.5
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• pp.364-371
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• 2018

Inhibition effects of alanine (Ala), histidine (His), methionine (Met) on the corrosion of aluminum were investigated in deaerated 0.5 M HCl and NaCl solution. In HCl solution the inhibition efficiency for the aluminum corrosion depended on the cathodic inhibition, and the inhibition efficiency was increased in the order of Met$10^{-4\;}M$ the adsorption process can be explained by Langmuir isotherm, however, in the case of higher concentration by Temkin logarithmic isotherm due to the interaction between the adsorbed molecules.

• Resources Recycling
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• v.8 no.1
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• pp.37-43
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• 1999

Studies have been conducted for the purpose of using manganese nodule and residue remained after extracting valuable metals [mm it as the adsorbent of cadmium wastewater. The study observed the adsorption percentage according to initial cadmium concentration and interpreted each adsorption systems by applying the Freundlich, Langmuir, and Temkin isotherms. The adsorption amounts increased as the initial concentration at cadmium ion increased, whereas the adsorption percentage decreased. Linearity was shown when applied to the Freundlich and Langmuir isotherms. The k value which evaluates the adsorption capacity of adsorbent in Freundlich isotherm, turned out to be 11.72, the highest in case of manganese nodule. The Xm value, the maximum adsorption amount of the adsorbate that adsorbs as a monolayer in Langmuir isotherm of manganese nodule, was estimated as 0.16, representing higher value compared with those of leached residue, leached residue-raw manganese nodule mixture, and activated carbon.

• Journal of the Korean Electrochemical Society
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• v.2 no.1
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• pp.23-26
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• 1999

The Langmuir adsorption isotherm at the $(Pt)/0.1M\;H_2SO_4$ electrolyte interface has been qualitatively analyzed using the ac impedance measurement and phase-shift method. The phase shift $(\phi)$ depends on both the cathode potential (E<0) and frequency (f) and is inversely proportional to the factional surface coverage $(\theta)$. At an intermediate frequency band (ca. $1\~100$ Hz), the phase-shift profile $(\phi\;vs.\;E)$ can be related to the fractional surface coverage $(\theta\;vs.\;E)$. The phase-shift profile $(\phi\;vs.\;E)$ can be used as an experimental method to estimate and analyze the Langmuir adsorption isotherm $(\theta\;vs.\;E)$. The equilibrium constant (K) and the standard free energy $({\Delta}G_{ads})$ of the adsorbed hydrogen atom $(H_{ads})\;and\;3\times10^{-4}$ and 20.1 kJ/mol, respectively.

• Korean Chemical Engineering Research
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• v.43 no.2
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• pp.230-235
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• 2005

Reversed-phase high-performance liquid chromatography (RP-HPLC) was used to determine the equilibrium isotherm of single and multi-components of dUrd(2'-deoxyuridine), dGuo(2'-deoxyguanosine), and dAdo(2'-deoxyadenosine) of 2'-deoxyribonucleosides by dynamic method. The composition of mobile phase was 90/10 vol.% (water/MeOH). With an increase in the injection volumes, the retention times were shorter and the peak shapes were triangle-shaped, so Langmuir-type isotherm was assumed. The Langmuir adsorption parameters were estimated by PIM (pulsed-input method), and the competitive Langmuir adsorption isotherm was further utilized. For the sample of the dUrd and dGuo whose retention times were relatively short, the agreement of between the calculated value and experimental data was fairly good in both single and multi-components, but for the dAdo, the last eluting component, some deviations were caused by non-linear and non-ideal properties.

• 한국전기화학회:학술대회논문집
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• 1999.10a
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• pp.19-19
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• 1999

• 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.