• Title, Summary, Keyword: isotherm

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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.

Discrimination of rival isotherm equations for aqueous contaminant removal systems

  • Chu, Khim Hoong
    • Advances in environmental research
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    • v.3 no.2
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    • pp.131-149
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    • 2014
  • Two different model selection indices, the Akaike information criterion (AIC) and the coefficient of determination ($R^2$), are used to discriminate competing isotherm equations for aqueous pollutant removal systems. The former takes into account model accuracy and complexity while the latter considers model accuracy only. The five types of isotherm shape in the Brunauer-Deming-Deming-Teller (BDDT) classification are considered. Sorption equilibrium data taken from the literature were correlated using isotherm equations with fitting parameters ranging from two to five. For the isotherm shapes of types I (favorable) and III (unfavorable), the AIC favors two-parameter equations which can easily track these simple isotherm shapes with high accuracy. The $R^2$ indicator by contrast recommends isotherm equations with more than two parameters which can provide marginally better fits than two-parameter equations. To correlate the more intricate shapes of types II (multilayer), IV (two-plateau) and V (S-shaped) isotherms, both indices favor isotherm equations with more than two parameters.

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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Adsorption isotherm and kinetics analysis of hexavalent chromium and mercury on mustard oil cake

  • Reddy, T. Vishnuvardhan;Chauhan, Sachin;Chakraborty, Saswati
    • Environmental Engineering Research
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    • v.22 no.1
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    • pp.95-107
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    • 2017
  • Adsorption equilibrium and kinetic behavior of two toxic heavy metals hexavalent chromium [Cr(VI)] and mercury [Hg(II)] on mustard oil cake (MOC) was studied. Isotherm of total chromium was of concave type (S1 type) suggesting cooperative adsorption. Total chromium adsorption followed BET isotherm model. Isotherm of Hg(II) was of L3 type with monolayer followed by multilayer formation due to blockage of pores of MOC at lower concentration of Hg(II). Combined BET-Langmuir and BET-Freundlich models were appropriate to predict Hg(II) adsorption data on MOC. Boyd's model confirmed that external mass transfer was rate limiting step for both total chromium and Hg(II) adsorptions with average diffusivity of $1.09{\times}10^{-16}$ and $0.97m^2/sec$, respectively. Desorption was more than 60% with Hg(II), but poor with chromium. The optimum pH for adsorptions of total chromium and Hg(II) were 2-3 and 5, respectively. At strong acidic pH, Cr(VI) was adsorbed by ion exchange mechanism and after adsorption reduced to Cr(III) and remained on MOC surface. Hg(II) removal was achieved by complexation of $HgCl_2$ with deprotonated amine ($-NH_2$) and carboxyl (COO-) groups of MOC.

Sensitivity Analysis of Amino Acids in Simulated Moving Bed Chromatography

  • Lee, Ju-Weon;Lee, Chong-Ho;Koo, Yoon-Mo
    • Biotechnology and Bioprocess Engineering:BBE
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    • v.11 no.2
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    • pp.110-115
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    • 2006
  • We conducted a sensitivity analysis of the simulated moving bed (SMB) chromatography with the case model of the separation of two amino acids phenylalanine and tryptophan. We consider a four-zone SMB chromatography where the triangle theory is used to determine the operating conditions. Competitive Langmuir isotherm model was used to determine the adsorption isotherm. The finite difference method is used to solve nonlinear partial differential equation (PDE) systems numerically. We examined the effects of alterations in the operating conditions(feed-extract, feed-raffinate, eluent-extract, eluent-raffinate, recycle, and switching time) and the adsorption isotherm parameters (Langmuir isotherm parameters a and b) on SMB efficiency. The variation range of operating conditions and Langmuir isotherm a was between -50 and 50% of original value and the variation range of the Langmuir isotherm b was between $2.25^{-5}$ and $2.25^5$ times of original value.

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.

Anomalous Fading Mechanism(Part 2) Sorption Isotherm of Congo Red on Cellophane Film in Absence of Salt (이상 퇴색의 Mechanism(제 2 보) Congo Red의 셀로판 막에의 염 부재하에서의 등온 흡착)

  • 하완식
    • Textile Science and Engineering
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    • v.10 no.1
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    • pp.36-39
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    • 1973
  • For the purpose of determining the quantity of dyes sorbed in monomolecular and aggregate state in the substrate, the sorption isotherm for Congo Red on cellophane film was determined at 97$^{\circ}C$ in absence of salt. A modification of existing sorption isotherm was attempted through discussion of the fading behavior of Congo Red sorbed only monomolecularly in the substrate. The data showed considerable correlation much more with the proposed sorption isotherm than with the generally used one. (Received Feb. 28, 1973)

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Lead Biosorption by Biosorbent Materials of Marine Brown Algae U. pinnatifida, H. fusiformis, and S. fulvellum

  • LEE Mingyu;KAM Sangkyu;LEE Donghwan
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.30 no.6
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    • pp.936-943
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    • 1997
  • Biosorbents of nonliving, dried marine brown algae Undaria pinnatifida, Hizikia fusiformis, and Sargassum fulvellum were investigated for their lead biosorption performances. As the amount of biosorbent added was increased, the lead removal by biosorbent materials increased but the lead biosorption capacities decreased. However the lead biosorption capacity by the biosorbent materials increased with increasing initial lead concentration and pH in the range of $C_o\;10\~500\;mg/L$. Among the biosorbent materials used in this study, the lead biosorption capacity in the solutions with no pH adjustment decreased in the following sequence: U. pinnatifida > H. fusiformis > S. fulvellum. Equilibrium parameters based on Langmuir and Freundlich isotherm were determined. It was found that the lead biosorption by biosorbent materials were expressed by the Langmuir isotherm better than the Freundlich isotherm.

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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.

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
    • Journal of the Korean Institute of 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.