• Journal of the Korean Geotechnical Society
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• v.27 no.4
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• pp.43-50
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• 2011

Steel-making slag was investigated as reactive material for removal of cadmium in coastal area. Batch experiments of the sorption isotherm experiment and kinetic sorption experiment were performed. Result of sorption isotherm was more adequately described by Langmuir model than Freundlich model and theoretical maximum capacity (${\beta}$) of cadmium onto steel-making slag was found. Results of kinetic sorption experiments were evaluated by pseudo second order model to investigate sorption characteristics of cadmium onto steel-making slag. Results showed that the equilibrium sorption amount of cadmium (q$q_e$) increased and the rate constant ($k_2$) and initial sorption rate (h) decreased as the initial cadmium concentration increased. The $q_e$ with simulated sea water was similar to that with deionized water and $k_2$ and h with simulated sea water was lower than those with deionized water. Results of kinetic experiments could be used to predict the result from sorption isotherm, since equilibrium sorption amounts calculated by pseudo second order model generally agreed with those measured from sorption isotherm. The reaction time for the target removal rate could be calculated by the pseudo second order model using kinetic sorption tests results.

• Journal of Korean Society on Water Environment
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• v.27 no.2
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• pp.141-146
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• 2011

Loess, a natural clay, was evaluated as an adsorbent for the decolorization of Acid Orange II, an azo and reactive dye, from aqueous solution. Adsorption studies were performed at $30^{\circ}C$ and the effect of reaction time, loess dosage, initial concentration, loess particle size, pH, agitation rate were investigated to determine the optimum operation conditions. The removal efficiencies of color were measured to evaluate the effectiveness of loess. From this study, it was found that optimal reaction time was 10 min. Color removal efficiencies of Acid Orange II were increased as higher loess dosage, initial concentration and agitation rate. However, color removal efficiencies decreased when pH is high and loess particle becomes large. Adsorption of Acid Orange II fitted to the pseudo-second-order rate kinetics more than first-order rate kinetics. Langmuir and Freundlich adsorption isotherm constants and correlation coefficients were calculated and compared. It was concluded that the adsorption data of Acid Orange II onto loess fitted to the Freundlich model more than Langmuir model.

• Resources Recycling
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• v.20 no.6
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• pp.28-36
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• 2011

The adsorption of nickel(Ni) from sulfuric acid solution was carried out by ion exchange method. A series of batch tests in synthetic solutions were carried out using Lewatit Monoplus TP 220 resin. The following experimental parameters, such as temperature, shaking rate, reaction time, pH, resin dosage and concentration of nickel ions etc. were investigated to establish the effective optimum conditions of nickel adsorption. The solution pH(2.0~5.0) and shaking rate had little effects on the adsorption of nickel and adsorption time of 72hours was required to reach equilibrium. The experimental results show a good agreement with Feundlich isotherm and pseudo-second order reaction. The adsorption behavior of Ni obtained from synthetic solution was compared with that of waste electroplating solution. Elution of nickel from loaded resin increased with increase in $H_2SO_4$ concentration.

• Resources Recycling
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• v.25 no.4
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• pp.60-67
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• 2016

This study was conducted to establish the adsorption-desorption mechanism and the optimum condition of chromatographic operation for separations of heavy rare earth elements (Gd, Tb, Dy) using a p507-containing resin. By employing Langmuir and Freundlich isotherm together with pseudo first and second order kinetics, absorption-desorption reaction mechanism was investigated. Langmuir and Freundlich isotherm was applied under assumption that adsorption reaction occurs in form of monolayer, and because the result was identical to the assumption, now we know adsorption of heavy rare earth elements occurs in form of monolayer. Concerning the pseudo first and second order kinetic, the pseudo second order seemed to be more suitable to represent heavy rare earth element adsorption mechanism. By using the extraction chromatography to separate heavy rare earth elements, ${\alpha}^{Tb}_{Gd}=1.24$, and ${\alpha}^{Dy}_{Tb}=1.03$ were confirmed in eluent HCl 0.25 M which indicates almost perfect separations of three elements. Furthermore, as concentrations of eluent became higher, the resolution value decreased and the elution area got shortened.

• Journal of Environmental Science International
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• v.22 no.9
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• pp.1161-1170
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• 2013

The efficiency of coal-based activated carbon in removing methylene blue (MB) and phenol from aqueous solution was investigated in batch experiments. The batch adsorption kinetics were described by applying pseudo-first-order, pseudo-second-order, and first order reversible reaction. The results showed that the adsorption of MB and phenol occurs complexed process including external mass transfer and intraparticle diffusion. The maximum adsorption capacity obtained from Langmuir isotherm was 461.0 mg/g for MB and 194.6 mg/g for phenol, respectively. The values of activation parameters such as free energy (${\Delta}G^0$), enthalpy (${\Delta}H^0$), and entropy (${\Delta}S^0$) were also determined as -19.0~-14.9 kJ/mol, 25.4 kJ/mol, and 135.2 J/mol K for MB and 51.8~54.1 kJ/mol, -29.0 kJ/mol, and -76.4 kJ/mol K for phenol, respectively. The MB adsorption was found to be endothermic and spontaneous process. However, the CV adsorption was found to be exothermic and non-spontaneous process.

• Journal of Environmental Science International
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• v.26 no.3
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• pp.363-371
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• 2017

This study evaluates the adsorption properties of Sr ions in an aqueous solution of the synthetic zeolite (Z-Y1) prepared using coal fly ash generated from a thermal power plant. In order to investigate the adsorption characteristics, the effects of various parameters such as the initial concentrations of Sr ion, contact time, and solution pH were investigated in a batch mode. The Langmuir and Redlich-Peterson model fitted the adsorption isotherm data better than the Freundlich model. The maximum adsorption capacity of Sr ions, as determined the Langmuir model, was 181.68 mg/g. It was found that by varying the Sr ion concentration, pH, and temperature, the pseudo-second-order kinetic model describes the adsorption kinetics of the Sr ion better than the pseudo-first-order kinetic model. The calculated thermodynamic parameters of ${\Delta}H^0$ and ${\Delta}G^0$ showed that the adsorption of Sr ions on Z-Y1 was occurred through a spontaneous and an endothermic reaction. We found that the adsorption of Sr ions by Z-Y1 was more affected by pH than by temperature and Sr ion concentration.

• Bulletin of the Korean Chemical Society
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• v.22 no.7
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• pp.669-672
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• 2001

Pseudo-first-order rate constants have been measured spectrophotometrically for the title reactions. The plot of kobs vs the concentration of alkali metal ethoxides is linear for the reactions performed in the presence of complexing age nt, 18-crown-6 ether, but curved upwardly for the corresponding reactions performed in the absence of the complexing agent, indicating that the alkali metal ions studied in this study behave as a catalyst. The catalytic effect was found to increase in the order Li+ << K+ ${\leq}$ Na+. Second-order rate constants were determined for the reactions with dissociated free ethoxide (kEtO-) and with ion paired alkali metal ethoxides (kEtO-M+ ) from ion pairing treatments. The magnitude of catalytic effect (kEtO-M+/kEtO-) was found to be 2.3, 9.5 and 8.7 for the reaction of 8-(5-nitroquinolyl) 2-furoate, while 1.4, 3.6 and 4.2 for that of 4-nitrophenyl 2-furoate, indicating that the catalytic effect is larger in the reaction of the former substrate than in that of the latter one. The larger catalytic effect was attributed to two possible complexing sites with alkali metal ions in the former substrate.

• Journal of Ginseng Research
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• v.5 no.2
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• pp.122-131
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• 1981

An aqueous extract s of fresh ginseng roots was heated at loot for 64 hrs. and the changes of color intensity, pH and the amount of free sugars and amino acids during the various intervals of the heating time were investigated. Color intensity and absorbance of the solution at 490nm were increased in proportion to the length of the heating time. Most of brown pigments produced during the treatment were water soluble, and pH 5.1 at initial stage of the solution, was slightly decreased at the final stages of the reaction. Sucrose, glucose and fructose were major free sugars in ginseng roots, and the amounts of sucrose was over 90 % of total free sugars. Sucrose. was largely decreased approximately 50%, by 64 hrs of the treatment, whereas sharp increase in the amount of glucose and fructose was observed during the reaction in the solution. The observed increase in reducing sugars, glucose and fructose was presumed due to hydrolysis of sucrose. Evidently, glucose and fructose were not important factor to control the browning reaction of the solution. Most of free amino acids and peptides except alanine and isoleucine especially arginine, serine and threonine, were sharply decreased up to 40 : 50% of the original concentration within 2 hrs. Accordingly, the content of free amino acids and peptides seems to be extremely important factor to control the browning reaction in ginseng. A free amino acid, presumed to be nor-leucine, was found in fresh ginseng root on the basis of re mention on liquid chromatography. Kinetic analysis of the browning reaction indicated a pseudo second order with respect to amino acid concentration at the initial stage.

• Journal of Microbiology and Biotechnology
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• v.11 no.5
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• pp.838-844
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• 2001

The enzyme Fuc aldolase from Methanococcus jannaschii that catalyzes the aldol condensation of DHAP and L-lactaldehyde to give fuculose-1-phosphate was inactivated by DEP. The inactivation was pseudo first-order in the enzyme and DEP, which was biphasic. A pseudo second-order rate constant of 120$M^{-1}min^{-1}$ was obtained at pH 6.0 and $25{\circ}C$. Quantifying the increase in absorbance at 240nm showed that four histidine residues per subunit were modified during the nearly complete inactivation. The statistical analysis and the time course of the modification suggested that two or three histidine residues were essential for activity. The rate of inactivation was dependent on the pH, and the pH inactivation data implied the involvement of the amino acid residue with a $pK_a$ value of 5.7. Fuc aldolase was protected against DEP inactivation by DHAP, indicating that the histidine residues were located at the active site of Fuc aldolase. DL-Glyceraldehyde, as an alternative substrate to L-lactaldehyde, showed no specific protection for the Fuc aldolase.

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