• Geotechnical Engineering
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• v.11 no.2
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• pp.121-138
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• 1995

The Langmuir competitive model and the IAS(ideal adsorption solution) model were eveluated and compared in a multisolute adsorption study using five organic compounds (phenol, 2, 4-dichlorophenol, 2, 4, 6-trichlorophenot brucine, and thiourea) and two soils. The chemicals were evaluated individually and in mixtures. In general, the IfS model predicted the equilibrium concentration of a chemical in a mixture better than the Langmuir model. The Langmuir model underestimated the sorption of phenol when the concentration of another compound in a mixture with phenol was high. Neither of the models predicted satisfactorily the equilibrium concentration of thiourea in the mixtures. Thiourea is an aliphatic compound while the other four chemicals are aromatic compounds.

• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.204-209
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• 2012

In this study, kinetics data was obtained for steam reforming reaction of ethane over the commercial ruthenium catalyst. The variables of ethane steam reforming were the reaction temperature, partial pressure of ethane, and steam/ethane mole ratio. Parameters for the power rate law kinetic model and the Langmuir-Hinshelwood model were obtained from the kinetic data. Also, sizing of steam reforming reactor was performed by using PRO/II simulator. The reactor size calculated by the power rate law kinetic model was bigger than that of using the Langmuir-Hinshelwood model for the same conversion of ethane. Reactor size calculated by the Langmuir-Hinshelwood model seems to be more suitable for the reactor design because the Langmuir-Hinshelwood model was more consistent with the experimental results.

• 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.

• Applied Chemistry for Engineering
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• v.24 no.4
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• pp.375-381
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• 2013

Kinetics data were obtained for steam reforming of methane and natural gas over the commercial nickel catalyst. Variables for the steam reforming were the reaction temperature and partial pressure of reactants. Parameters for the Power law rate model and the Langmuir-Hinshelwood model were obtained from the kinetic data. As a result of the reforming reaction using pure methane as a reactant, the reaction rate could be determined by the Power law rate model as well as the Langmuir-Hinshelwood model. In the case of methane in natural gas, however, the Langmuir-Hinshelwood model is much more suitable than the Power law rate model in terms of explaining methane reforming reaction. This behavior can be attributed to the competitive adsorption of methane, ethane, propane and butane in natural gas over the same catalyst sites.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.8
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• pp.1097-1104
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• 2003

The current study analyzes Langmuir slip boundary condition theoretically and it is tested in practical numerical analysis for separation-associated flow. Slip phenomenon at the channel wall is properly implemented by various numerical slip boundary conditions including Langmuir slip model. Compressible backward-facing step flow is compared to other analysis results with the purpose of diatomic gas Langmuir slip model validation. The numerical solutions of pressure and velocity distributions where separation occurs are in good agreement with other numerical results. Numerical analysis is conducted for Reynolds number from 10 to 60 for a prediction of separation at T-shaped micro manifold. Reattachment length of flows shows nonlinear distribution at the wall of side branch. The Langmuir slip model predicts fairly the physics in terms of slip effect and separation.

• Resources Recycling
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• v.15 no.3 s.71
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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.

• Journal of the Korean Institute of Gas
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• v.19 no.2
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• pp.37-44
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• 2015

We proposed the improved Langmuir adsorption relations considering volume change effect of coal matrix during primary production of CBM and Enhanced-CBM with injection of carbon dioxide or CCS in coalseam but also volumetric strain. To verify this model, experimental data of pure gas adsorption such as $CO_2$, $CH_4$, and $N_2$ on coals were used to compare conventional Langmuir model with this model. From the results, we obtained that the larger adsorption capacity of coal and the higher adsorption affinity of gas, the larger error occur with Langmuir model. Using this model, however, we found not only substantially better fit in all condition but also reasonable volumetric strain of the coal matrix. We also applied this volume modified pure gas adsorption model to the IAS model to describe gas adsorption and volumetric strain for mixed gas. This modified-IAS model fitting experimental data by Hall et al(1994) improved accuracy of mixed gas adsorption calculation compared with conventional model.

• Journal of the Korean GEO-environmental Society
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• v.10 no.7
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• pp.25-32
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• 2009

The main objective of this study was to examine the removal properties of Cu from water by inflated vermiculites. The component of vermiculites was analyzed by XRF and the concentration of Copper ion was measured by UV-VIS. Serial batch Kinetic tests and batch sorption tests were conducted to determine the removal characteristics for Cu in aqueous solutions. The result shows that removal rate, $K_{obs}$, of Cu are 0.73, 1.52, and 1.71 for initial pH 3, pH 4, pH 5, respectively, and are 3.19, 1.90, and 0.73 for the initial concentration of $1mg\;L^{-1}$, $5mg\;L^{-1}$, $10mg\;L^{-1}$, respectively. It leads to the conclusion that the removal rates are inversely proportional to the initial Cu concentration and are increased proportionally to the initial pHs. Finally, Sorption data were correlated with both Langmuir and Freundlich isotherms. As a result, Langmuir and Freundlich models were well fitted to batch isotherm data with good values of the determination coefficient. but the determination coefficient value for the Freundlich model fit was slightly higher than that of Langmuir model (0.965 for the Freundlich model and 0.936 for the Langmuir model). Using the Langmuir model, the maximum sorption capacity ($Q_{max}$), Freundlich partition coefficient, and the numerical value of n wrer estimated as $1,250mg\;kg^{-1}$, $635.1L\;kg^{-1}$ and 1.69, respectively. These results show that the inflated vermiculites could be used as an excellent adsorbent for copper contained in various types of aqueous solutions.

• 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.

• Journal of Microbiology and Biotechnology
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• v.14 no.2
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• pp.250-255
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• 2004

The aim of this work was to investigate the adsorption isotherm and kinetic model for the biosorption of lead $(Pb^{2+})$ by Rhodotorula aurantiaca and to examine the environmental factors for this metal removal. Within five minutes of contact, $Pb^{2+}$ sorption reached nearly 86% of the total $Pb^{2+}$ sorption. The optimum initial pH value for removal of $Pb^{2+}$ was 5.0. The percentage sorption increased steeply with the biomass concentration up to 2 g/l and thereafter remained more or less constant. The Langmuir sorption model provided a good fit throughout the concentration range. The conformity of these data to the Langmuir model indicated that biosorption of $Pb^{2+}$ by R. aurantiaca could be characterized as a monolayer, single-site type phenomenon with no interaction between ions adsorbed in neighboring sites. The maximum $Pb^{2+}$ sorption capacity $(q_{max})$ and Langmuir constant (b) were 46.08 mg/g of biomass and 0.04 l/mg, respectively. The pseudo second-order equation was well fitted to the experimental data. The correlation coefficients for the linear plots of t/q against t for the second-order equation were 0.999 for all the initial concentrations of biosorbent for contact times of 180 min. The theoretical $q_{eq}$ value was very close to the experimental $q_{eq}$ value.