• Applied Chemistry for Engineering
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• v.30 no.2
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• pp.190-197
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• 2019

The adsorption of methyl green dye using an activated carbon from an aqueous solution was investigated. Adsorption experiments were carried out as a function of the adsorbent dose, initial concentration, contact time and temperature. The Langmuir isotherm model showed a good fit to the equilibrium adsorption data. Based on the estimated Langmuir separation factor, ($R_L=0.02{\sim}0.106$), this process could be employed as the effective treatment (0 < $R_L$ < 1). It was found that the adsorption was a physical process with the adsorption energy (E) value range between 316.869 and 340.049 J/mol obtained using Dubinin-Radushkevich equation. The isothermal saturation capacity obtained from brunauer emmett teller (BET) model increased with increasing the temperature. The kinetics of adsorption followed a pseudo second order model. The free energy and enthalphy values of -5.421~-7.889 and 31.915 kJ/mol, respectively indicated that the adsorption process follows spontaneous endothermic reaction. The isosteric heat of adsorption increased with the increase of equilibrium adsorption amounts, and the total interaction of the adsorbent - adsorbate increased as the surface coverage increased.

• Clean Technology
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• v.23 no.4
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• pp.413-420
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• 2017

The batch experiments and response surface methodology (RSM) have been applied to the investigation of the Cs adsorption with zeolite X synthesized using coal fly ash generated from the thermal power plant. Regression equation formulated for Cs adsorption was represented as a function of response variables. The model was highly relevant because the decision coefficient ($r^2$) was 0.9630. It was confirmed from the statistical results that the removal efficiency of Cs was affected by the order of experimental factors as pH > Cs concentration > temperature. The adsorption kinetics were more accurately represented by a pseudo second-order model. The maximum adsorption capacity calculated from the Langmuir isotherm model was $151.52mg\;g^{-1}$ at 293 K. Also, according to the thermodynamic parameters calculated from Vant Hoff equation, it could be confirmed that the adsorption reaction was an endothermic reaction and a spontaneous process.

• Korean Journal of Food Science and Technology
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• v.35 no.2
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• pp.211-216
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• 2003

Absorption characteristics of hot air-. vacuum-, and freeze-dried ginger powder were investigated. Monolayer moisture content as determined by GAB equation was $0.257{\sim}0.540\;H_2O/g$, showing higher significance than BET equation. Absorption enthalpy was calculated based on different drying methods and water activities. Absorption energy decreased with increasing water activity but was not affected by drying method. Isotherm curves showed a typical sigmoid form. Among models applied for predicting equilibrium moisture content, Caurie model was the best fit model for ginger powder, showing the lowest prediction deviation of $1.2{\sim}5.4%$, followed by Henderson then Bradley models. The prediction model equations for the moisture content were established by in(time), water activity, and temperature.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.2
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• pp.66-73
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• 2017

This study was to evaluate the influential parameters such as intial Cs concentration, reaction temperature, contact time and pH variation of solution on Cs adsorption. Using the experimental data, adsorption kinetics, isotherms and thermodynamic properties were analyzed. The Cs ion adsorption of the zeolite X was effective in the range from pH 5 to 10 and reached equilibrium after 60 minutes. The adsorption kinetics and isotherms of Cs ion with the zeolite X was described well by the pseudo-second-order kinetic and Langmuir isotherm model. The maximum adsorption capacities of Cs ion calculated from Langmuir isotherm model at 293~333 K were from 303.03 mg/g to 333.33 mg/g. It was found that thermodynamic property of Cs ion absorption on the zeolite X was spontaneous and endothermic reaction. The experimental data were fitted a second-order polynomial equation by the multiple regression analysis. The values of the dependent variable calculated by this best fitted model equation were in very good agreement with the experimentally obtained values.

• Journal of Advanced Marine Engineering and Technology
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• v.15 no.2
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• pp.64-72
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• 1991

The unsteady, two-dimensional laminar flow and heat transfer of an incompressible, constant-property fluid flowing around a circular cylinder are numerically analyzed. The Navier-Strokes equation and the energy equation are solved by the finite difference method. The range of the Reynolds number is 10 to 100 and the Prandtl number considered is 0.7. The contours of the flow pattern, equi-vorticity line and isotherm pattern around a circular cylinder are shown. Also, numerical solutions of the surface vorticity, pressure coefficient, drag coefficient, local Nusselt number and mean Nusselt number are obtained. The numerical results for the final time fo calculation are compared with the other available experimental and theoretical results for the steady state and are found to be in good agreement with them.

• YAKHAK HOEJI
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• v.15 no.1
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• pp.1-7
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• 1971

When a large quantity of insoluble drugs was added into a solution containing a small amount of soluble drugs, the latter was adsorbed to the former. Their adsorption was expected to alter the drug activity. Berberine hydrochloride (BH) was selected as a soluble drug and tested with frequently combined insoluble drugs and antacids for their adsorption phenomena in prufied water, gastric and intetinal fluid test solutions, respectively. The adsorption isotherms of kaolin and natural anuminum silicate with BH in the three media fitted the Langmuir (LM) equation, and that of talc in purified water and gastric fluid fitted it, but in intestinal fluid it fitted the Freudlich quation. The adsorption isotherm of aluminum hydroxide fitted the LM equation only in intestinal fluid. The degree of adsorption of BH in purified water and gastric fluid is in the following order: magnesium trisilicate, kaolin, natural aluminum silicate and talc; in intestinal fluid: magnesium trisilicate, kaolin, talc, natural aluminum silicate and aluminum hydroxide. Magnesium stearate did not adsorb BH.

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

• Advances in environmental research
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• v.2 no.3
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• pp.245-260
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• 2013

Biosorption represents a technological innovation as well as a cost effective excellent remediation technology for cleaning up radionuclides from aqueous environment. In the present study, a bacteria strain FB12 with high adsorption rate of uranium ion was isolated from the vicinity of the nuclear power plant. It was tentatively identified as Bacillus sp.FB12 according to the 16S rDNA sequencing. Efforts were made to further improve the adsorption rate and genetic stability by UV irradiation and UV-LiCl cooperative mutagenesis. The improved strain named Bacillus sp.UV32 obtains excellent genetic stability and a high adsorption rate of 95.9%. The adsorption of uranium U (VI) by Bacillus sp.UV32 from aqueous solution was examined as a function of metal ion concentration, cell concentration, adsorption time, pH, temperature, and the presence of some foreign ions. The adsorption process of U (VI) was found to follow the pseudo-second-order kinetic equation. The adsorption isotherm study indicated that it preferably followed the Langmuir adsorption isotherm. The thermodynamic parameters values calculated clearly indicated that the adsorption process was feasible, spontaneous and endothermic in nature. These properties show that Bacillus sp.UV32 has potential application in the removal of uranium (VI) from the radioactive wastewater.

• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3184-3190
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• 2012

Color impurity in industrial effluents pose a significant risk to human health and the environment, so much effort has been expended to degrade them using various methods, including the use of clay minerals as adsorbent. The purpose of this study was to advance understanding of the mechanisms for the removal of methylene blue (MB) from aqueous solutions onto montmorillonite as an adsorbent. Preliminary experiments showed that montmorillonite was effective for this purpose and adsorption equilibrium could be reached in about 24 h. Adsorption capacity of the clay decreased with increase in temperature and ionic strength, and increased with in pH. The fitness of equilibrium data to common isotherm equations such as the Langmuir, Freundlich, Elovich, Temkin and Dubinin-Radushkevich were tested. The Langmuir equation fitted to equilibrium data better than all tested isotherm models. Thermodynamic activation parameters such as ${\Delta}G^0$, ${\Delta}S^0$ and ${\Delta}H^0$ were also calculated and results were evaluated. As result montmorillonite clay was found as effective low cost adsorbent for removal of cationic dyes from waste waters.

• Journal of Korean Society on Water Environment
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• v.28 no.2
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• pp.197-201
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• 2012

The objective of this study was to evaluate the removal efficiency of arsenite and arsenate using composite adsorbents with various mixing ratio of recycled aluminum oxides and $TiO_2$. From batch adsorption experiments, while the removal of As(III) was almost same with 4 different composite samples in the entire pH range, the removal of As(V) was substantially increased as the weight ratio of $TiO_2$ in composite samples reduced and showed anionic adsorption characteristics. Both adsorption of As (III) and As(V) on composite samples followed pseudo-second-order adsorption equation and C-3 showed faster reaction rate for the removal of arsenic. From the adsorption isotherm experiments, Langmuir isotherm explained well and the maximum adsorption capacities of arsenic were obtained with C-1.