• 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.

• 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.

• 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.

• Clean Technology
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• v.9 no.2
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• pp.81-85
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• 2003

A simple method of isotherm determination for HPLC is discussed. The equilibrium-dispersive model describing the behavior of elution peaks in HPLC for single component is solved numerically by using PDE solver Macsyma$^{(R)}$(Macsyma Inc., Arlington, MA, USA.) and compared to the experimental data obtained in overloaded isocratic chromatography with caffeine as model species. The effect of sample concentration and flow velocity on the band profiles of elution peaks are described.

• 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.

• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.255-261
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• 2016

Adsorption experiments of Acid Yellow 14 dye using activated carbon were carried out as function of adsorbent dose, pH, initial concentration, contact time and temperature. The equilibrium adsorption data were analyzed by Langmuir, Freundlich and Temkin isotherm model. The experimental data were best represented by Freundlich isotherm model. Base on the estimated Freundlich constant (1/n=0.129~0.212) and Langmuir separation factor ($R_L=0.202{\sim}0.243$), this process could be employed as effective treatment method. The heat of adsorption of Temkin isotherm model was 5.101~9.164 J/mol indicated that the adsorption process followed a physical adsorption. Adsorption kinetics experimental data were modeled using the pseudo-first-order and pseudo-second-order kinetic equation. It was shown that pseudo-second-order kinetic equation could best describe the adsorption kinetics. Base on the negative Gibbs free energy (-4.81~-10.33 kJ/mol) and positive enthalpy (+78.59 kJ/mol) indicate that the adsorption is spontaneous and endothermic process.

• Journal of the Korean Electrochemical Society
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• v.16 no.4
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• pp.211-216
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• 2013

At Pt(111), Pt(100), Pt, and Rh interfaces, the Frumkin adsorption isotherm of underpotentially deposited hydrogen (UPD H) and related electrode kinetic data are determined using the standard Gibbs energy of adsorption. The Temkin adsorption isotherm of UPD H correlating with the Frumkin adsorption isotherm of UPD H is readily determined using the correlation constants between the Temkin and Frumkin or Langmuir adsorption isotherms. At the Pt(111), Pt(100), Pt, and Rh interfaces, the lateral repulsive interaction between the UPD H species is interpreted using the interaction parameter for the Frumkin adsorption isotherm. The lateral repulsive interaction between the UPD H species at the Pt(111), Pt(100), Pt, and Rh interfaces is significantly different from the lateral attractive interaction between the overpotentially deposited hydrogen (OPD H) species at Pt, Ir, and Pt-Ir alloy interfaces.

• Advances in environmental research
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• v.4 no.3
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• pp.197-210
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• 2015

Hexavalent chromium [Cr (VI)] adsorption on lateritic soil and lateritic soil blended with black cotton (BC) soil, marine clay and bentonite clay were studied in the laboratory using batch adsorption techniques. In the present investigation the natural laterite soil was blended with 10%, 20% and 30% BC soil, marine clay and bentonite clay separately. The interactions on test soils have been studied with respect to the linear, Freundlich and Langmuir isotherms. The linear isotherm parameter, Freundlich and Langmuir isotherm parameters were determined from the batch adsorption tests. The adsorption of Cr (VI) on natural laterite soil and blended laterite soil was determined using double beam spectrophotometer. The distribution coefficients obtained were 1.251, 1.359 and 2.622 L/kg for lateritic soil blended with 10%, 20% and 30% BC soil; 5.396, 12.973 and 48.641 L/kg for lateritic soil blended with marine clay and 5.093, 8.148 and 12.179 L/kg for lateritic soil blended with bentonite clay respectively. The experimental data fitted well to the Langmuir model as observed from the higher value of correlation coefficient. Soil pH and iron content in soil(s) has greater influence on Cr (VI) adsorption. From the study it is concluded that laterite soil can be blended with clayey soils for removing Cr (VI) by adsorption.

• Bulletin of the Korean Chemical Society
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• v.34 no.8
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• pp.2358-2366
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• 2013

Iron oxide (ferrihydrite, hematite, and magnetite) coated silica gels were prepared using a low-cost, easily-scalable and straightforward method as the adsorbent material for arsenic removal application. Adsorption of the anionic form of arsenic oxyacids, arsenite ($AsO^{2-}$) and arsenate ($AsO{_4}^{3-}$), onto hematite coated silica gel was fitted against non-linear 3-parameter-model Sips isotherm and 2-parameter-model Langmuir and Freundlich isotherm. Adsorption kinetics of arsenic could be well described by pseudo-second-order kinetic model and value of adsorption energy derived from non-linear Dubinin-Radushkevich isotherm suggests chemical adsorption. Although arsenic adsorption process was not affected by the presence of sulfate, chloride, and nitrate anions, as expected, bicarbonate and silicate gave moderate negative effects while the presence of phosphate anions significantly inhibited adsorption process of both arsenite and arsenate. When the actual efficiency to remove arsenic was tested against 1 L of artificial arsenic-contaminated groundwater (0.6 mg/L) in the presence competing anions, the reasonable amount (20 g) of hematite coated silica gel could reduce arsenic concentration to below the WHO permissible safety limit of drinking water of $10{\mu}g/L$ without adjusting pH and temperature, which would be highly advantageous for practical field application.

• Carbon letters
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• v.22
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• pp.14-24
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• 2017

Carboxylated multi-wall carbon nanotubes (MWCNTs-COOH) have been used as efficient adsorbents for the removal of picric acid from aqueous solutions under stirring and ultrasound conditions. Batch experiments were conducted to study the influence of the different parameters such as pH, amount of adsorbents, contact time and concentration of picric acid on the adsorption process. The kinetic data were fitted with pseudo-first order, pseudo-second-order, Elovich and intra-particle diffusion models. The kinetic studies were well described by the pseudo-second-order kinetic model for both methods. In addition, the adsorption isotherms of picric acid from aqueous solutions on the MWCNTs were investigated using six two-parameter models (Langmuir, Freundlich, Tempkin, Halsey, Harkins-Jura, Fowler-Guggenheim), four three-parameter models (Redlich-Peterson, Khan, Radke-Prausnitz, and Toth), two four-parameter equations (Fritz-Schlunder and Baudu) and one five-parameter equation (Fritz-Schlunder). Three error analysis methods, correlation coefficient, chi-square test and average relative errors, were applied to determine the best fit isotherm. The error analysis showed that the models with more than two parameters better described the picric acid sorption data compared to the two-parameter models. In particular, the Baudu equation provided the best model for the picric acid sorption data for both methods.