• Applied Chemistry for Engineering
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• v.7 no.4
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• pp.653-660
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• 1996

For oxygen PSA process development, adsorbed amount of oxygen and nitrogen on various adsorbents were measured corresponding Langmuir isotherm parameters were measured. A reasonable adsorbent for oxygen process was selected based on the effective adsorbed amount. The PSA process consists of adsorption, desorption, pressurization, purging and pressure equilization steps. Adsorption pressure was about 2 atm and desorption pressure was between 120 torr to 400torr. Cycle time of 2-bed PSA process was 80 seconds and that of 3-bed oxygen PSA process was 180 seconds. In order to compare and analyze operation characteristics and economic feasibilities of 2-bed and 3-bed oxygen PSA processes, productivity, oxygen concentration and recovery were compared and the effect of purge and pressurization steps on the performance of PSA processes were analyzed. For the commercial scale oxygen PSA process, capital and electricity cost were estimated. In the range of $O_2$ production less than $700Nm^3/hr$, the 2-bed process is conformed more feasible in economic view point.

• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.472-478
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• 2019

A stable desalination method of the hardness substance such as $Ca^{2+}$ by controlling the total charge (TC) supplied to the membrane capacitive deionization (MCDI) cell was studied. The adsorption (1.5 V) and desorption (0.0 V) were repeated 30 times while varying the TC in the adsorption process. The concentration and pH of effluent, adsorption and desorption amounts, current densities and cell potentials were analyzed in the desalination process. The maximum allowable charge (MAC) of the carbon electrode used in MCDI cell was measured to be 46 C/g. As a result of operation at TC (40 C/g) below the MAC value, electrode reactions did not occur, resulted in the stable desalination characteristics for a long-term operation. When operating at TCs (50, 60 C/g) above the MAC value, however, the concentration and pH of effluent varied greatly. Also, the scale was formed on the electrode surface due to electrode reactions, and the electric resistance of the cell gradually increased. It was thus concluded that it is possible to remove stably the hardness substance without any electrode reactions by controlling the charge supplied to MCDI cell during the adsorption process.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6B
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• pp.677-682
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• 2006

Dodecyldimethylethylammonium (DDDEA), a cationic surfactant, and aluminum metal ions were used with bentonite to synthesize to synthesize an improved organo bentonite. Among three different synthesis procedure for organo bentonites, aluminium-pillared bentonite showed the highest DDDEA sorption, which indicated that aluminium-pillared organo bentonite would exhibit the highest sorption capacity for organic contaminants. Aluminium pillared organo bentonite also showed a high sorption capability for phosphorus, while it did not exhibit strong sorption for nitrate. In the meantime, more desorption was observed with aluminium-pillared organo bentonite than ordinary organo bentonites.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2006.04a
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• pp.529-530
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• 2006

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2010.04a
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• pp.640-641
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• 2010

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2009.11a
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• pp.204-205
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• 2009

• Proceedings of the Materials Research Society of Korea Conference
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• 2005.05a
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• pp.317-317
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• 2005

• Proceedings of the Materials Research Society of Korea Conference
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• 2006.05a
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• pp.34.1-34.1
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• 2006

• Journal of the Korean Chemical Society
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• v.54 no.5
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• pp.533-540
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• 2010

An activated carbon was tested for its ability to remove transition metal ions from aqueous solutions. Physical, chemical and liquid-phase adsorption characterizations of the carbon were done following standard procedures. Studies on the removal of Ni(II), Cu(II) and Fe(III) ions were attempted by varying adsorbate dose, pH of the metal ion solution and time in batch mode. The equilibrium adsorption data were fitted with Freundlich and Langmuir and the isotherm constants were evaluated, equilibrium time of the different three metal ions were determined. pH was found to have a significant role to play in the adsorption. The processes were endothermic and the thermodynamic parameters were evaluated. Desorption studies indicate that ion-exchange mechanism is operating.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.149-154
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• 2012

The adsorption and desorption behavior of biofilter-medium was investigated on the performance of an adsorption column. Continuous flow-isothermal adsorption experiments were performed to treat waste air containing such a VOC as ethanol under the same condition of > 90% relative humidity as the condition of the feed to a biofilter process. In case of feeding waste air containing ethanol of 1,000 ppmv (or 2,050 mg ethanol/$m^3$) to the adsorption system at the rate of 2 L/min, the onsets of its breakthrough and reaching the state of dynamic equilibrium at the exit had been delayed 10 and 3 times, respectively, later than those at the 1st stage sampling port. Moreover, in case of 2,000 ppmv (or 4,100 mg ethanol/$m^3$), they had been delayed 9 and 3 times, respectively. Thus, regardless of feeding concentration, the ratios of delaying period were observed to be quite consistent each other at the exit of the adsorption column. With regard to the period of desorption, the ratios of delaying period were consistent each other to be 1.5 for both cases. In addition, the effect of microbial activity and sterilization-process was studied on adsorption equilibrium. The ethanol concentration in the vapor phase of vials packed with sterilized granular activated carbon (GAC) was quite consistent to that with unsterilized GAC. However, the ethanol concentrations in the vapor phase of vials packed with unsterilized compost and the unsterilized mixture of GAC and compost were higher than those with sterilized compost and the sterilized mixture of GAC and compost, respectively.