• Title, Summary, Keyword: Langmuir adsorption isotherm

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Altered Langmuir Adsorption Isotherm under the Consideration of the Displacement of Water Molecules with Adsorbate Ion at the Surface of Adsorbent (흡착제(吸着劑) 표면(表面)에서의 흡착질(吸着質)과 물분자(分子)의 치환(置換)을 고려(考慮)한 수정(修正) Langmuir 등온흡착식(等溫吸着式))

  • Kim, Dong-Su
    • Resources Recycling
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    • v.15 no.3
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    • pp.81-86
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    • 2006
  • Altered Langmuir adsorption isotherm has been suggested for adsorption reactions occurring in aqueous environment based upon the concept of the steric displacement between adsorbates and water molecules at the surface of adsorbent. For the adsorption of $Cd^{2+}$ on activated carbon, the suggested adsorption isotherm was shown to be more well applied to the experimental results compared with the classical Langmuir adsorption isotherm. Based on this, regarding the adsorption system which following the Langmuir model more precise design and controllable operation of the process were considered to be attainable when the adsorption process is analyzed employing the altered adsorption isotherm.

Pure Gas Adsorption Equilibrium for H2/CO/CO2 and Their Binary Mixture on Zeolite 5A (Zeolite 5A에서의 H2/CO/CO2 단성분 및 혼합성분의 흡착평형)

  • Ahn, Eui-Sub;Jang, Seong-Cheol;Choi, Do-Young;Kim, Sung-Hyun;Choi, Dae-Ki
    • Korean Chemical Engineering Research
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    • v.44 no.5
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    • pp.460-467
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    • 2006
  • Adsorption experiments for $H_2$, $CO_2$, CO, and their binary mixtures on zeolite 5A were performed by static volumetric method. Experimental data were obtained at temperatures of 293.15, 303.15 and 313.15 K and at pressures to 25 atm. The parameters obtained from single component adsorption isotherm. Multicomponent adsorption equilibria could be predicted and compared with experimental data. Langmuir isotherm, Langmuir-Freundlich isotherm and Dual-Site Langmuir isotherm be used to predict the experimental results for binary adsorption equilibria of $CO_2/CO$ and $H_2/CO_2$ on zeolite 5A. Dual-Site Langmuir isotherm showed the best agreement with the experimental results.

Determination of the Langmuir and Temkin Adsorption Isotherms of H for the Cathodic H2 Evolution Reaction at a Pt/KOH Solution Interface Using the Phase-Shift Method

  • Chun Jang-H.;Jeon Sang-K.;Chun Jin-Y.
    • 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.

A Study on VOCS Adsorption at Low Pressure (낮은 분압의 VOCs의 흡착에 관한 연구)

  • Song, Hun-Taek;Kan, Sung-Won;Min, Byong-Hun;Suh, Sung-Sup
    • Clean Technology
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    • v.9 no.4
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    • pp.153-161
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    • 2003
  • This study was carried out as a basic experiment for development of adsorption process in which benzene and toluene was adsorbed on activated carbon. In the static adsorption experiment, Adsorption character of benzene and toluene was studied by change of temperature and pressure. Activated carbon 12~20mesh and activated carbon 20~40mesh was used as adsorbents, Benzene, toluene and nitrogen as adsorbates. Experimental data were obtained to fitted to Langmuir isotherm and dependence was acquired. Parameters of adsorption heat and adsorption constant was obtained. Static adsorption experiment for binary mixtures confirmed that Langmuir isotherm parameters could be applicable to Extended Langmuir isotherm. Experimental technique used in this study only requires pressure measurement and this technique is different from the conventional method which measures gas mole compositions before adsorption and after adsorption. The dynamic adsorption experiment was carried out and the experimental results was compared with the computer simulation results. In this study, basic data was acquired to decide adsorption conditions in the process.

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A Study on the Adsorption Characteristics of Benzene using Activated Carbon from Sewage Sludge (하수슬러지 활성탄의 벤젠 흡착특성)

  • Kim, Jong-Moon;Chung, Chan-Kyo;Lee, Taek-Ryong;Min, Byong-Hun;Kim, Hyung-Jin;Kwon, Young-Shik
    • Clean Technology
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    • v.15 no.4
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    • pp.265-272
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    • 2009
  • In this study the experiments on the static adsorption of benzene were carried out using activated carbon made from sewage sludge. The experiment was performed at 303.15 K, 318.15 K and 333.15 K under the pressure up to 7.999kPa. Isothermal adsorption curves were obtained using Langmuir isotherm, Freundlich isotherm and Toth isotherm for comparison. Based on fitting the adsorption quantity of Benzene (q), the isothermal adsorption curves obtained from Langmuir isotherm and Toth isotherm showed the higher accuracy. Although there was little difference in accuracy between result from Langmuir isotherm and that from Toth isotherm, the adsorption quantity of Benzene (q) was expressed in terms of Langmuir isotherm because less parameters were required for Langmuir isotherm than for Toth isotherm. Moreover SEM images of the activated carbon from sewage sludge and the commercial activated carbon were taken to observe the pore size development. The results showed that the perforation development of the commercial activated carbon (DARCO A.C., SPG-100 A.C.) was better than that of activated carbon from sewage sludge. Adsorption quantity of benzene on commercial activated carbon was confirmed to be higher than that on activated carbon from sewage sludge. However the maximum adsorption quantity of benzene on activated carbon from sewage sludge was close to that on SGP-100 A.C. at 303.15K. Therefore, we may conclude that it is feasible to commercialize the process to manufacturing activated carbon from sewage sludge.

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Measurement of Langmuir Adsorption Equilibrium by Elution-curve Method and Frontal Analysis (용출곡선법과 Frontal Analysis를 이용한 Langmuir 흡착평형식의 측정)

  • Choi, Yong Seok;Lee, Chong Ho;Row, Kyung Ho
    • Applied Chemistry for Engineering
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    • v.10 no.5
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    • pp.672-676
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    • 1999
  • Adsorption isotherm is the most fundamental information in adsorption separation-process. Directly from the elution profile of a peak, the elution-curve method and frontal analysis(FA) were utilized to measure the adsorption isotherm in this work. Using RP-HPLC, sample and the buffer added in mobile phase were 5'-GMP and sodium phosphate, respectively. In this experimental condition, the retention time was decreased with increase in the injected mass of sample. And the front part of a peak was very stiff, so Langmuir adsorption isotherm might be applied. By the elution-curve method, the parameters used in the isotherm were obtained by optimization method, while by the FA, the concentrations of stationary phase were measured from the elution curve and the isotherm was determined by regression analysis. Compared to FA, the consumption of sample was less, and only one or two injections were needed by the elution-curve method. Finally, the effect of concentration of sodium phosphate in mobile phase on the parameters of the isotherm was investigated.

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A Study on the Adsorption Characteristics of Benzene Using Activated Carbon from Waste Timber (폐벌목 활성탄의 벤젠 흡착특성)

  • Kim, Jong-Moon;Chung, Chan-Kyo;Min, Byong-Hun
    • Clean Technology
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    • v.19 no.4
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    • pp.430-436
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    • 2013
  • In this study, experiments on the static adsorption of benzene were carried out using activated carbon made from Pinus koraiensis which is normally discarded waste timber in South Korea. The experiment were performed at 303.15 K, 318.15 K and 333.15 K under the pressure up to 7.999 kPa. Isothermal adsorption curves were obtained using Langmuir isotherm, Freundlich isotherm and Toth isotherm for comparison. Based on the fitting, the adsorption quantity of Benzene (q), the isothermal adsorption curves obtained from Langmuir isotherm and Toth isotherm showed the higher accuracy. Although there was little difference in accuracy between result from Langmuir isotherm and that from Toth isotherm, the adsorption quantity of Benzene (q) was expressed in terms of Langmuir isotherm because less parameters were required for Langmuir isotherm than for Toth isotherm. Moreover SEM images of the activated carbon from Pinus koraiensis and the commercial activated carbon were taken to observe the pore size development. The results showed that the perforation development of activated carbon from Pinus koraiensis (waste timber) was better than that of commercial activated carbon (DARCO A.C., SPG-100 A.C.). Adsorption quantity of benzene on activated carbon from Pinus koraiensis was confirmed to be higher than that on commercial activated carbon. Therefore, we may conclude that it is feasible to commercialize the process to manufacturing activated carbon from waste timber.

Adsorption characteristic of Cu(II) and phosphate using non-linear and linear isotherm equation for chitosan bead (비선형과 선형 등온흡착식을 이용한 키토산비드의 구리와 인산염의 흡착특성)

  • Kim, Taehoon;An, Byungryul
    • 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 (qm) 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.

Isotherm, Kinetic and Thermodynamic Characteristics for Adsorption of Acenaphthene onto Sylopute (실로퓨트에 의한 아세나프텐 흡착에 관한 등온흡착식, 동역학 및 열역학적 특성)

  • Cho, Da-Nim;Kim, Jin-Hyun
    • 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.

Protein Adsorption on Ion Exchange Resin: Estimation of Equilibrium Isotherm Parameters from Batch Kinetic Data

  • Chu K.H.;Hashim M.A.
    • Biotechnology and Bioprocess Engineering:BBE
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    • v.11 no.1
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    • pp.61-66
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    • 2006
  • The simple Langmuir isotherm is frequently employed to describe the equilibrium behavior of protein adsorption on a wide variety of adsorbents. The two adjustable parameters of the Langmuir isotherm - the saturation capacity, or $q_m$, and the dissociation constant, $K_d$ - are usually estimated by fitting the isotherm equation to the equilibrium data acquired from batch equilibration experiments. In this study, we have evaluated the possibility of estimating $q_m$ and $K_d$ for the adsorption of bovine serum albumin to a cation exchanger using batch kinetic data. A rate model predicated on the kinetic form of the Langmuir isotherm, with three adjustable parameters ($q_m,\;K_d$, and a rate constant), was fitted to a single kinetic profile. The value of $q_m$ determined as the result of this approach was quantitatively consistent with the $q_m$ value derived from the traditional batch equilibrium data. However, the $K_d$ value could not be retrieved from the kinetic profile, as the model fit proved insensitive to this parameter. Sensitivity analysis provided significant insight into the identifiability of the three model parameters.