• Journal of Environmental Science International
• /
• v.22 no.12
• /
• pp.1651-1660
• /
• 2013

The adsorption of lithium ion onto zeolite was investigated depending on contact time, initial concentration, cation forms, pH, and adsorption isotherms by employing batch adsorption experiment. The zeolite was converted into different forms such $K^+$, $Na^+$, $Mg^{2+}$, $Ca^{2+}$, and $Al^{3+}$. The zeolite had the higher adsorption capacity of lithium ion in $K^+$ form followed by $Na^+$, $Ca^{2+}$, $Mg^{2+}$, and $Al^{3+}$ forms, which was in accordance with their elctronegativities. The lithium ion adsorption was explained using the Langmuir, Freundlich, and Dubinin-Radushkevich adsorption isotherms and kinetic models. Adsorption rate of lithium ion by zeolite modified in $K^+$ form was controlled by pseudo-second-order and particle diffusion kinetic models. The maximum adsorption capacity obtained from Langmuir isotherm was 17.0 mg/g for zeolite modified in $K^+$ form. The solution pH influenced significantly the lithium ions adsorption capacity and best results were obtained at pH 5-10.

• Transactions of the Korean hydrogen and new energy society
• /
• v.16 no.4
• /
• pp.307-314
• /
• 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.

• Environmental Engineering Research
• /
• v.10 no.2
• /
• pp.45-53
• /
• 2005

Metal oxide particles with mole ratio of aluminum: titanium of 1:1 were synthesized by a sol-gel method. Langmuir (a) and Freundlich (b) adsorption isotherms of dissolved lead [Pb(Ⅱ)] ion on the metal oxide particles containing aluminum and titanium were determined as follows, respectively,(a) , (b) at pH 6where, correlation coefficients (R2) of Langmuir and Freundlich adsorption isotherms were 0.95 and 0.96, respectively.The overall adsorption rate of Pb(Ⅱ) on the metal oxide particles containing aluminum and titanium was determined by a differential bed reactor. The overall adsorption rate at pH 6 was as a following equation.at pH 6

• Bulletin of the Korean Chemical Society
• /
• v.9 no.4
• /
• pp.244-248
• /
• 1988

Multilayer adsorption isotherms of nitrogen on hexagonal boron nitride, ${\gamma}$-alumina, and silica-gel powders are determined at the liquid nitrogen temperature using a gravimetric adsorption apparatus. The volume (V) of the adsorbed gas are plotted against the statistical thickness(t) of the adsorbed layer, and the t-method area are calculated from the slope of these V-t plots to compare with the BET area. A number of universal adsorption isotherms and the Frenkel-Halsey-Hill equation are used one after another in calculating the statistical thickness. The appropriateness of the FHH equation as an universal adsorption isotherm is discussed finally.

• Journal of Korean Society of Water and Wastewater
• /
• v.30 no.6
• /
• pp.691-698
• /
• 2016

This study was carried out to investigate the characterization of iron oxide nanotubes (INTs) by anodization method and applied adsorption isotherms and kinetic models for phosphate adsorption. SEM analysis was conducted to examine the INTs surface formation. Further XRD and XPS analysis were performed to observe the crystal structure of INTs before and after phosphate adsorption. AFM analysis was conducted to determine of Fe foil surface before and after anodization. Phosphate stock solution for adsorption experiment was prepared by $KH_2PO_4$. The batch experiment was conducted using 20 ml phosphate stock solution and $40cm^3$ of INTs in 50 ml conical tube. Adsorption isotherms were applied Langmuir and Freundlich models for adsorption equilibrium test of INTs. Pseudo first order and pseudo second order models were applied for interpretation of adsorption rate by reaction time. The determination coefficient ($R^2$) values of Langmuir and Freundlich models were 0.9157 and 0.8876 respectively.

• Journal of Korea Soil Environment Society
• /
• v.1 no.1
• /
• pp.81-88
• /
• 1996

To study the Cd adsorption in the presence of competing ions in soil-solution interphase, three soil samples from the Bt horizon were taken and analyzed for their physical and chemical properties. Adsorption of ethylene glycol monoethyl ether(EGME) and N, were determined to establish the specific surface area of the soils. We attempted to establish a qeneralizing competitive sorption isotherms for soils of entirely different composition of the solid phase, resulting in the routine use as a guidelines for the fate of reactive solute in soil profiles. Many physicochemical factors including competitive adsorption bettween solutes will affect the general adsorption phenomena as shown in a single not only on the soil:solution ratio used, but also on the surface areas of its respective soil samples. This phenomenon was attributed to competition Cd for sorption sites with Mg by different soil constituents. These adsorption isotherms are able to use as examples to demonstrate that this phenomenon can complicate the development of a standardized batch adsorption procedure as well as interpreting fate and adsorption of toxic inorganic compounds.

• Korean Chemical Engineering Research
• /
• v.61 no.1
• /
• pp.97-108
• /
• 2023

Two carbonaceous adsorbents CAT and CARBOPAL were tested for reducing the concentration of the three herbicides in water: 2,4-D (2,4-dichlorophenoxyacetic acid), TCP (2,4,6-trichlorophenol) and metolachlor. Textural and chemical characterization of the adsorbents include nitrogen isotherms, FTIR, titration and thermogravimetric analyses. Adsorption was studied in discontinuous adsorption experiments at different pH values. The experimental adsorption isotherms data were fitted to four theoretical models. Adsorbent characterization reveals that CAT has higher micropore area, lower pore diameter and lower acidity than CARBOPAL. The adsorption is a second-order process and the isotherms best fitted to Sips model. The efficiency of the process depends mainly on the charge of the adsorbate for TCP and 2,4-D, but it depends on the charge of the surface for metolachlor. Adsorption capacity is higher on CAT for 2,4-D and TCP (small molecules), and it is higher on CARBOPAL for metolachlor (large molecules). Theoretical calculations clearly support this assumption.

• Korean Journal of Soil Science and Fertilizer
• /
• v.29 no.2
• /
• pp.86-91
• /
• 1996

Water vapor adsorption isotherms were measured for samples of the A horizons of five typical Korean soils. The experimental data were fitted to the BET and Aranovich adsorption equations. The adsorption isotherms studied followed the BET equation for the relative water vapor pressures in 0.03-0.33 range and the Aranovich equation in 0.03-0.6 range. The calculated surface areas were higher for Aranovich than for BET and opposite relations were found for adsorption energies. For the description of the water adsorption on soils, the use of the Aranovich theory is recommended.

• The Journal of Engineering Research
• /
• v.6 no.2
• /
• pp.85-98
• /
• 2004

The adsorption equilibrium data for the binary gas mixture system from the pure gas adsorption data of carbon dioxide and ethylene on ZSM-5 prepared were predicted. The binary gas mixture adsorption data have been examined against predicted values by two models-the vacancy solution model(VSM) and the statistical thermodynamic model(STM), using parameters obtained from the single component isotherm. The binary gas mixture data for the carbon dioxide-ethylene system were obtained for cation exchanged forms of ZSM-5 for the gas phase carbon dioxide mole fraction of 0.752 at $37^{\circ}C$ and 1 atm. The experimental adsorption phase diagrams were obtained for carbon dioxide-ethylene on sodium form ZSM-5 synthesized. The single component adsorption isotherms for carbon dioxide and ethylene were also obtained for this zeolite. The single component data were used to obtain parameters derived in two models. These parameters were, in turn, used to predict the binary mixture isotherms for this zeolite. Both the vacancy solution and the statistical thermodynamic models give satisfactory predictions of adsorption phase diagrams for the binary gas mixtures of carbon dioxide and ethylene on sodium exchanged ZSM-5. Also the correlation between the experimental data and the predicted values is generally in good agreement. The system appears to show ideal behavior with a relatively constant separation factor. The slight increase in adsorption capacity with an increase in ionic radius is due, in part, to the higher polarizability associated with larger cations.

• Carbon letters
• /
• v.19
• /
• pp.99-103
• /
• 2016

Porous carbons have attracted much attention for their novel application in gas storage. In this study, porous graphite nano-fiber (PGNFs)-based graphite nano fibers (GNFs) were prepared by KOH activation to act as adsorbents. The GNFs were activated with KOH by changing the GNF/KOH weight ratio from 0 through 5 at 900℃. The effects of the GNF/KOH weight ratios on the pore structures were also addressed with scanning electron microscope and N₂ adsorption/desorption measurements. We found that the activated GNFs exhibited a gradual increase of CO₂ adsorption capacity at CK-3 and then decreased to CK-5, as determined by CO₂ adsorption isotherms. CK-3 had the narrowest micropore size distribution (0.6–0.78 nm) among the treated GNFs. Therefore, KOH activation was not only a significant method for developing a suitable pore-size distribution for gas adsorption, but also increased CO₂ adsorption capacity as well. The study indicated that the sample prepared with a weight ratio of ‘3’ showed the best CO₂ adsorption capacity (70.8 mg/g) as determined by CO₂ adsorption isotherms at 298 K and 1 bar.