• Journal of Soil and Groundwater Environment
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• v.10 no.6
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• pp.45-55
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• 2005

The geothermal research has been carried out on the Heunghae, Pohang geothermal area know as having geo-heat-flow area in the Korean peninsula. This study results so far indicate that geothermal water in the area is in peripheral waters of hydrothermal area and is not in equilibrium with the reservoir rock. The average oxygen and hydrogen stable isotope values are as follows: deep groundwater $(average:\;{\delta}^{18}O=-10.1\%_{\circ},\;{\delta}D=-65.8\%_{\circ})$, intermediate groundwater (average: $(average:\;{\delta}^{18}O=-8.9\%_{\circ},\;{\delta}D=-59.6\%_{\circ})$, shallow groundwater $(average:\;{\delta}^{18}O=-8.0\%_{\circ},\;{\delta}D=-53.6\%_{\circ})$, surface water $(average:\;{\delta}^{18}O=-7.9\%_{\circ},\;{\delta}D=-53.3\%_{\circ})$ respectively. Deep groundwaters was originated from a local meteoric water recharged from distant, topographically high mountain region and not affected by the sea water. High temperature zone inferred from water geothermometers is around D-1, D-5, D-6, 1-04 well zones. The estimated enthalpy from Silica-enthalpy mixing model is near 410 kJ/kg, which corresponds to the temperature of $98^{\circ}C$, and in consistent with the result of Na-K and K-Mg geothermometer.

• Applied Chemistry for Engineering
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• v.24 no.3
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• pp.327-332
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• 2013

Batch experiments were carried out for adsorption equilibrium, kinetics and thermodynamic parameters of the brilliant brown R onto granular activated carbon. The operating variables studied were the initial dye concentration, contact time and temperature. Experimental equilibrium adsorption data were fitted to Langmuir and Freundlich adsorption isotherm by linear regression method. The equilibrium process was well described by Freundlich isotherm model and from the determined separation factor (1/n), granular activated carbon could be employed as an effective treatment for the removal of bismarck brown R. From kinetic experiments, the adsorption processes were found to confirm the pseudo second order model with a good correlation and the adsorption rate constant ($k_2$) increased with increasing adsorption temperature. Thermodynamic parameters like the activation energy, change of Gibbs free energy, enthalpy, and entropy were also calculated to predict the nature of adsorption in the temperature range of 298~318 K. The activation energy was determined as 8.73 kJ/mol for 100 mg/L. It was found that the adsorption of bismarck brown R on the granular activated carbon was physical process. The negative Gibbs free energy change (${\Delta}G$ = -2.59~-4.92 kJ/mol) and the positive enthalpy change (${\Delta}H$ = +26.34 kJ/mol) are indicative of the spontaneous and endothermic nature of the adsorption process.

• Clean Technology
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• v.17 no.4
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• pp.346-352
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• 2011

The adsorption characteristics of propineb pesticide onto activated carbon has been investigated for the adsorption in aqueous solution with respect to initial concentration, contact time and temperature in batch experiment. The Langmuir and Freundlich adsorption models were applied to described the equilibrium isotherms and isotherm constants were also determined. The Freundlich model agrees with experimental data well. slope of isotherm line indicate that activated carbon could be employed as effective treatment for removal of propineb. The pseudo first order, pseudo second order kinetic models were use to describe the kinetic data and rate constants were evaluated. The adsorption process followed a pseudo second order model, and the adsorption rate constant($k_2$) decreased with increasing initial concentration of propineb. The activation energy, change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption. The estimated values for change of free energy were -7.28, -8.27 and -11.66 kJ/mol over activated carbon at 298, 308 and 318 K, respectively. The results indicated toward a spontaneous process. The positive value for change of enthalpy, 54.46 kJ/mol, found that the adsorption of propineb on activated carbon is an endothermic process.

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.96-102
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• 2014

Adsorption of metanil yellow onto granular activated carbon were studied in a batch system. Various operation parameters such as adsorbent dosage, pH, initial concentration, contact time and temperature were optimized. Experimental equilibrium adsorption data were analyzed by Langmuir and Freundlich adsorption isotherm. The equilibrium process was described well by Freundlich isotherm model. From determined separation factor (1/n), adsorption of metanil yellow by granular activated carbon could be employed as effective treatment method. By analysis of kinetic experimental data, the adsorption process were found to confirm to the pseudo second order model with good correlation and the adsorption rate constant ($k^2$) decreased with increasing initial concentration. Thermodynamic parameters like activation energy, change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption in the temperature range of 298~318 K. The activation energy was determined as 23.90 kJ/mol. It was found that the adsortpion of metanil yellow on the granular activated carbon was physical process. The negative Gibbs free energy change (${\Delta}G=-2.16{\sim}-6.55kJ/mol$) and the positive enthalpy change (${\Delta}H=+23.29kJ/mol$) indicated the spontaneous and endothermic nature of the adsorption process, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.10
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• pp.1720-1725
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• 2004

Absorption characteristics of green tea powder were investigated. The monolayer moisture content determined by GAB equation was 0.024~0.052 g $H_2O$/g dry solid. The absorption enthalpy was calculated with different particle size and various water activities. It showed that the absorption energy was decreased with increasing water activity but no difference was found on particle size increasement. Among models applied for predicting equilibrium moisture content, Halsey model was the best fit model for green tea powders, showing the lowest prediction deviation of 2.1~4.0%. The prediction model equations for the water activity was established as function of relative humidity, time and temperature. The model equation will be helpful for future work on drying and storage of green tea powder.

• 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.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.1
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• pp.73-82
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• 2012

A 2-dimensional heterogeneous reactor model was developed and simulated for a tube reactor of packed bed where the steam-$CO_2$ combined reforming reaction of natural gas proceeded to produce synthesis gas. Under the reactor feeding rate, 45 $Nm^3$/h, of the reactant gas stream, the 2-dimensional heterogeneous reactor model showed the similar results to those from the ASPEN simulator although there were some discrepancies between the two in the temperature and the $H_2$/CO ratio of the reformed gas at the reactor exit. The calculated enthalpy difference between the reformed gas at the reactor exit and the reactant gas fed to the reactor was closely correspondent to the total amount of heat transferred to the reactor interior from the furnace. This supports that the 2-dimensional heterogeneous reactor model was reasonably established and the numerical solution was properly obtained.

• Journal of Environmental Science International
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• v.25 no.12
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• pp.1623-1632
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• 2016

Zeolite (FZ) prepared using coal fly ash from an Ulsan industrial complex was immobilized with polysulfone (PS) to fabricate PS-FZ beads. The prepared PS-FZ beads were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The optimum ratio for preparing PS-FZ beads was 1 g of PS to 2 g of FZ. The removal efficiencies of Sr and Cu ions by the PS-FZ beads increased as the solution pH increased and nearly reached a plateau at pH 4. A pseudo-second-order model morel fit the adsorption kinetics of both ions by the PS-FZ beads better than a pseudo-first-order model. The Langmuir isotherm model fit the equilibrium data well. The maximum adsorption capacities calculated from the Langmuir isotherm model were 46.73 mg/g and 62.54 mg/g for the Sr and Cu ions, respectively. Additionally, the values of thermodynamic parameters such as free energy (${\Delta}G^{\circ}$), enthalpy (${\Delta}H^{\circ}$) and entropy (${\Delta}S^{\circ}$) were determined. The results implied that the prepared PS-FZ beads could be interesting an alternative material for Sr and Cu ion removal.

• Membrane and Water Treatment
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• v.11 no.1
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• pp.69-77
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• 2020

Former studies revealed that sepiolite thermally treated at high temperature have high adsorption capacity for phosphate. However, its micron size (75 ㎛) limits its application to water treatment. In this study, we synthesized sepiolite impregnated polysulfone (PSf) beads to separate it easily from an aqueous solution. PSf beads with different sepiolite ratios were synthesized and their efficiencies were compared. The PSf beads with 30% impregnated sepiolite (30SPL-PSf bead) possessed the optimum sepiolite ratio for phosphate removal. Kinetic, equilibrium, and thermodynamic adsorption experiments were performed using the 30SPL-PSf bead. Equilibrium adsorption was achieved in 24 h, and the pseudo-first-order model was suitable for describing the phosphate adsorption at different reaction times. The Langmuir model was appropriate for describing the phosphate adsorption onto the 30SPL-PSf bead, and the maximum adsorption capacity of the 30SPL-PSf bead obtained from the model was 24.48 mg-PO₄/g. Enthalpy and entropy increased during the phosphate adsorption onto the 30SPL-PSf bead, and Gibb's free energy at 35 ℃ was negative. An increase in the solution pH from 3 to 11 induced a decrease in the phosphate adsorption amount from 27.30 mg-PO₄/g to 21.54 mg-PO₄/g. The competitive anion influenced the phosphate adsorption onto the 30SPL-PSf bead was in the order of NO₃^- > SO₄^2- > HCO_3^-. The phosphate breakthrough from the column packed with the 30SPL-PSf bead began after ~2000 min, reaching the influent concentration after ~8000 min. The adsorption amounts per unit mass of 30SPL-PSf and removal efficiency were 0.775 mg-PO₄/g and 61.6%, respectively. This study demonstrates the adequate performance of 30SPL-PSf beads as a filter for phosphate removal from aqueous solutions.

• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.255-261
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• 2016

Adsorption experiments of Acid Yellow 14 dye using activated carbon were carried out as function of adsorbent dose, pH, initial concentration, contact time and temperature. The equilibrium adsorption data were analyzed by Langmuir, Freundlich and Temkin isotherm model. The experimental data were best represented by Freundlich isotherm model. Base on the estimated Freundlich constant (1/n=0.129~0.212) and Langmuir separation factor ($R_L=0.202{\sim}0.243$), this process could be employed as effective treatment method. The heat of adsorption of Temkin isotherm model was 5.101~9.164 J/mol indicated that the adsorption process followed a physical adsorption. Adsorption kinetics experimental data were modeled using the pseudo-first-order and pseudo-second-order kinetic equation. It was shown that pseudo-second-order kinetic equation could best describe the adsorption kinetics. Base on the negative Gibbs free energy (-4.81~-10.33 kJ/mol) and positive enthalpy (+78.59 kJ/mol) indicate that the adsorption is spontaneous and endothermic process.