• Nuclear Engineering and Technology
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• v.49 no.3
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• pp.534-540
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• 2017

The adsorption of uranium (VI) by calcium alginate beads was examined by batch experiments. The effects of environmental conditions on U (VI) adsorption were studied, including contact time, pH, initial concentration of U (VI), and temperature. The alginate beads were characterized by using scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. Fourier transform infrared spectra indicated that hydroxyl and alkoxy groups are present at the surface of the beads. The experimental results showed that the adsorption of U (VI) by alginate beads was strongly dependent on pH, the adsorption increased at pH 3~7, then decreased at pH 7~9. The adsorption reached equilibrium within 2 minutes. The adsorption kinetics of U (VI) onto alginate beads can be described by a pseudo first-order kinetic model. The adsorption isotherm can be described by the Redlich-Peterson model, and the maximum adsorption capacity was 237.15 mg/g. The sorption process is spontaneous and has an exothermic reaction.

• Journal of Microbiology and Biotechnology
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• v.11 no.5
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• pp.776-780
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• 2001

Based on the static and dynamic adsorption of Streamline DEAE, a modified tank-in-series model including particle size distribution was used to describe the adsorption performance of bovine serum albumin in an expanded bed. The calculated results indicated that the suggested model was able to simulate breakthrough curves under various conditions.

• Journal of the Korean Geotechnical Society
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• v.26 no.9
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• pp.37-45
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• 2010

Sorption characteristics of arsenic on furnace slag were investigated to remove arsenic from groundwater using furnace slag, which is industrial waste generated from steel company. Adsorption isotherm experiments and kinetic sorption experiments were performed and the chemical characteristics of supernatants from these experiments were analyzed. Results showed that all supernatants were alkaline (above pH 9) and the highest ion concentration in the solution was found with calcium (30~50 mg/L). Results of adsorption isotherms were more adequately described by the Freundlich model than Langmuir model. From adsorption isotherms experiments, it was noted that the adsorption amount of As(V) was 87% higher than that of As(III). Results of kinetic sorption experiments were more properly fitted by pseudo second order (PSO) model than pseudo first order model. Equilibrium adsorption amount ($q_e$) and relaxation time ($t_r$) calculated from PSO model increased with initial concentration of arsenic. Equilibrium adsorption amount of As(V) was higher than that of As(III) and relaxation time of As(V) was shorter than that of As(III). Adsorption isotherm results could be predicted by kinetic adsorption results, since equilibrium adsorption amount calculated through PSO model generally agreed with equilibrium adsorption amount measured from adsorption isotherm.

• Journal of the Korean GEO-environmental Society
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• v.11 no.1
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• pp.45-51
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• 2010

Cadmium (Cd) adsorption by the activated carbon containing hydroxyapatite (HAP) was investigated. Cd adsorption with different HAP mass ranged from 10% to 30%. With more HAP, more Cd was adsorbed. These results suggest that the higher HAP dose causes an increase of the ion exchange potential in HAP sorbent. Kinetics and equilibrium studies were investigated in series of batch adsorption experiments. Langmuir and Freundlich isotherm models were fit to the equilibrium data and Cd adsorption on HAP sorbent were found to follow the Freundlich isotherm model well in the initial adsorbate concentration range. The simple kinetic model, the pseudo first order kinetic model and the pseudo second order kinetic model, were used to investigate the adsorption. The adsorption reaction of Cd followed the pseudo second order kinetic model, and the adsorption pseudo second order kinetic constants ($k_2$) increased with increasing initial HAP amounts onto activated carbon. Also, intraparticle diffusion model was used to investigate the adsorption mechanism between adsorbate and adsorbent in the aqueous phase. Surface adsorption reaction and intraparticle diffusion occur simultaneously Cd adsorption mechanism from aqueous phase in this study.

• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.458-465
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• 2020

Isotherms, kinetics and thermodynamic properties for adsorption of acid fuchsin (AF) dye by activated carbon were carried out using variables such as dose of adsorbent, pH, initial concentration and contact time and temperature. The effect of pH on adsorption of AF showed a bathtub with high adsorption percentage in acidic (pH 8). Isothermal adsorption data were fitted to the Freundlich, Langmuir, and Dubinin-Radushkevich isotherm models. Freundlich isothem model showed the highest agreement and confirmed that the adsorption mechanism was multilayer adsorption. It was found that adsorption capacity increased with increasing temperature. Freundlich's separation factor showed that this adsorption process was an favorable treatment process. Estimated adsorption energy by Dubinin-Radushkevich isotherm model indicated that the adsorption of AF by activated carbon is a physical adsorption. Adsorption kinetics was found to follow the pseudo-second-order kinetic model. Surface diffusion at adsorption site was evaluated as a rate controlling step by the intraparticle diffusion model. Thermodynamic parameters such as activation energy, Gibbs free energy, enthalpy entropy and isosteric heat of adsorption were investigated. The activation energy and enthalpy change of the adsorption process were 21.19 kJ / mol and 23.05 kJ / mol, respectively. Gibbs free energy was found that the adsorption reaction became more spontaneously with increasing temperature. Positive entropy was indicated that this process was irreversible. The isosteric heat of adsorption was indicated physical adsorption in nature.

• Journal of Environmental Science International
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• v.24 no.2
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• pp.151-162
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• 2015

The adsorption characteristics of Sr ions and Cs ions in single and binary solution by zeolite A were investigated in batch experiment. The adsorption rate of Sr ions and Cs ions by zeolite A obeyed pseudo-second-order kinetic model in single and binary solution. The initial adsorption rates (h) and adsorption capacities of both ions obtained from pseudo-second-order kinetic model, and the values were decreased with increasing concentration of the competitive ions (0~1.5 mM). Also, adsorption isotherm data in binary solution were well fitted to the extended Langmuir model, the maximum adsorption capacities of Sr and Cs calculated from the model were 1.78 mmol/g and 1.64 mmol/g, respectively. The adsorption of Sr and Cs ions by zeolite A was carried out in the presence of other cations such as $Na^+$, $K^+$, $Mg^{2+}$ and $Ca^{2+}$. The results showed that the zeolite A can maintain a relatively high adsorption capacity for Sr and Cs ions and exhibits a high selectivity in the presence of competitive cations. The effect of competition had an order of $Ca^{2+}$ > $K^+$ > $Mg^{2+}$ > $Na^+$ for Sr ions and $K^+$ > $Ca^{2+}$ > $Na^+$ > $Mg^{2+}$ for Cs ions at the same cation concentration.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.11
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• pp.804-811
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• 2011

The aim of this study is to evaluate the applicability of adsorption models for understanding adsorption properties of adsorbents. For this study, the adsorption charateristics of $NO_3^-$ by commercial anion exchange resin, PA-308, were investigated in bach process. The adsorption kinetic data for $NO_3^-$ by anion exchange resin showed two stage process comprising a fast initial adsorption process and a slower second adsorption process. Both the pseudo-first-order kinetic model and the pseudo-second-order kinetic model could not be used to predict the adsorption kinetics of $NO_3^-$ onto anion exchange resin for the entire sorption period. Only the fast initial portion ($t{\leq}20min$) of adsorption kinetics was found to follow pseudo-first-order kinetic model and controlled mainly by external diffusion that is very fast and high, whereas, the slower second portion (t > 20 min) of adsorption kinetics seems to be controlled by a second-order chemical reaction and by intraparticle diffusion.

• Journal of Environmental Science International
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• v.27 no.5
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• pp.299-308
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• 2018

The adsorption characteristics of Cu ions were studied using the zeolite Na-A synthesized from Jeju volcanic rocks. The effects of various operating parameters such as initial concentration of Cu ions, contact time, solution pH, and solution temperature were investigated in batch experiments. The adsorption of Cu ions by Na-A zeolite was fitted well by pseudo-second-order kinetics and the Langmuir isotherm model. The maximum adsorption capacity determined using the Langmuir isotherm model was 152.95 mg/g. In addition, the adsorption of Cu ions by zeolite Na-A was primarily controlled by particle diffusion model in comparison with the film diffusion model. As the temperature increased from 303 K to 323 K, ${\Delta}G^o$ decreased from -2.22 kJ/mol to -3.41 kJ/mol, indicating that the adsorption of Cu ions by Na-A zeolite is spontaneous process.

• Journal of Environmental Science International
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• v.26 no.5
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• pp.609-619
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• 2017

The removal characteristics of 2,4-dinitrophenol (2,4-DNP) from an aqueous solution by commercial Wood-based Activated Carbon (WAC) have been studied. The effects of various experimental parameters were investigated using a batch adsorption technique. The adsorption capacity of 2,4-DNP by WAC increased with a decrease in the dosage and particle size of WAC, temperature and the initial pH of the solution, and increased with an increase in the initial concentration of the solution. The adsorption equilibrium data were best described by the Redlich-Peterson isotherm model. The maximum adsorption capacities of 2,4-DNP by WAC were 573.07 mg/g at 293 K, 500.00 mg/g at 313 K, and 476.19 mg/g at 333 K, decreasing with increasing temperature. The kinetic data were well fitted to the pseudo-second-order model, and the results of the intra-particle diffusion model suggested that the adsorption process was mainly controlled by particle diffusion. The thermodynamic analysis indicated that the adsorption of 2,4-DNP by WAC was an endothermic and spontaneous process.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.6
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• pp.609-615
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• 2015

This study was carried out for characterization of MIO synthesized in our laboratory by co-precipitation method and applied isotherm and kinetic models for adsorption properties. XRD analysis were conducted to find crystal structure of synthesized MIO. Further SEM and XPS analysis was performed before and after phosphate adsorption, and BET analysis for surface characterization. Phosphate stock solution was prepared by KH2PO4 for characterization of phosphate adsorption, and batch experiment was conducted using 50 ml conical tube. Langmuir and Freundlich models were applied based on adsorption equilibrium test of MIO by initial phosphate solution. Pseudo first order and pseudo second order models were applied for interpretation of kinetic model by temperature. Surface area and pore size of MIO were found $89.6m^2/g$ and 16 nm respectively. And, the determination coefficient ($R^2$) value of Langmuir model was 0.9779, which was comparatively higher than that of Freundlich isotherm model 0.9340.