• Applied Chemistry for Engineering
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• v.16 no.5
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• pp.719-723
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• 2005

Organic-inorganic hybrid mesoporous materials were prepared by co-condensation of organosilanes with tetraethyl orthosilicate (TEOS) or 1,2-bis(triethoxysilyl) ethane (BTSE). Their removal capability of volatile organic compounds (VOCs) in the air was evaluated and compared with that of inorganic hydrophilic mesoporous material, SBA-15 that was prepared with TEOS only. It was found that the increased hydrophobicity of mesoporous materials due to the presence of organic group, could enhance the VOCs removal by adsorption in the air. An organic-inorganic hybrid material prepared by the co-condensation of BTSE/phenyl triethoxysilane (90/10 by weight) was a typical example of superior adsorbent. It was also observed that these organic-inorganic hybrid materials can be utilized as absorbents for the removal of oil dispersed in water.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.3
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• pp.330-338
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• 2010

In this study, removal characteristics of nitrogen oxides $(NO_x)$ from road transport by using peat as the packing media for biodegradation have been investigated in the long term. Physicochemical and biological treatment of peatmixed media eliminates any requirement to use chemical substances and also facilitates the biodegradable actions of microorganism. Safe biodegradation of pollutants, no need to apply additional microbes owing to their active growth, and no generation of secondary pollutants were found in this experiment. It was concluded that average removal efficiencies of nitric oxide (NO) and nitrogen dioxide $(NO_2)$ were 80% and 97% respectively with respect to the linear velocity 35~40 mm/s and 0.3 ppm ozone concentration in the long period operation. Inflow concentration of nitric oxide over 0.05 ppm was suitable when pretreated with ozone. Non-ozone stage was performed with linear velocity 20~100 mm/s and then the average removal efficiency of nitric oxide and nitrogen dioxide were 38% and 94% respectively. Other results showed that the apparent static pressure was raised with increases in applied water content and aerial velocity in mixed media during fan operation.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.5
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• pp.507-513
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• 2005

Increasing amounts of anthropogenic $CO_2$ emitted to the atmosphere are believed to be a significant factor in global climate change. Hence, the method of chemical absorption has been suggested to separate and recover acid gases such as $CO_2$. In this study, the characteristics of absorption and regeneration of $CO_2$ for the absorbent which adding HMDA (hexamethylenediamine) into AMP (2-amino-2-methyl-1-propanol), hindered amine, was investigated in lab-scale absorption/regeneration reactor. As a result of this study, the removal efficiency of $CO_2$ increased when adding $5.9\%,\;11.7\%\;and\;23.4\%$ HMDA into $30\%$ AMP respectively. Also, the removal efficiency of $CO_2$ increased $6.5\%,\;8.4\%,\;10.3\%$ respectively as compared to AMP alone when the gas flow rate was 7.5 SL/min. In addition, all absorbents used in the study revealed the high stripping efficiency, which was almost $99\%$, at the temperature of $110^{\circ}C$. Thus, the regeneration tower should be operated at $110^{\circ}C$. At this time, the concentration of exhausted $CO_2$ was higher than $99\%$.

• Journal of Powder Materials
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• v.8 no.2
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• pp.91-97
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• 2001

The conventional debinding process in metal injection molding is very long time-consuming and unfriendly environmental method. Especially, in such a case of injection molded parts from hard and fine metal powder, such as WC-Co, an extremely long period of time is necessary in the conventional slow binder removal process. On the other hand, supercritical debinding is thought to be the effective method which is appropriate to eliminate the aforementioned inconvenience in the prior art. The supercritical fluid has high diffusivity and density, it can penetrate quickly into the inside of the green metal bodies, and extract the binder. In this paper, super-critical debinding is compared with wicking debinding process. Wax-based binder system is used in this study. The binder removal rate in supercritical $CO_2$ have been measured at $65^{\circ}C$, 75$^{\circ}C$ in the pressure range from 20 MPa to 28 MPa. Pores and cracks in silver bodies after sintering were observed using SEM When the super-critical $CO_2$ debinding was carried out at 75$^{\circ}C$, almost all the wax (about 70 wt% of binder) was removed in 2 hours under 28 MPa and 2.5 hours under 25 MPa.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.158-161
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• 2003

To develop an effective adsorbent for radio active Carbon Dioxide, $^14CO_2$, which is discharged to nearby atmosphere from nuclear power plants of CANDU type, we made some preliminary adsorbents and tested their abilities of $CO_2$ removal. The chemical agents used was LiOH and we supported or impregnated it on the surface or the internal volume of activated Carbon(GW-H). The physical and chemical properties of various adsorbents were measured using methods such as XRD, BET. SEM images were taken to investigate the change of surface morphology of the adsorbents. Finally, amount of $CO_2$ adsorption of them were verified under specific conditions. We found that mechanical mixing of LiOH and activated Carbon showed the maximum $CO_2$ removal ability, while surface activation of activated Carbon by Nitric Acid-treatment enhanced its $CO_2$ removal efficiency to some degree.

• Journal of the Semiconductor & Display Technology
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• v.16 no.1
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• pp.22-28
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• 2017

The result of stripping process for the removal of the post etch/ash Photoresist (PR) residue on an aluminum patterned wafer by using supercritical $CO_2$ ($sc-CO_2$) mixture, was investigated by scanning of electron microscope (SEM) inspection of wafer, measuring the cloud points and visual observation of the state of $sc-CO_2$ mixtures. It was found that $sc-CO_2$ mixtures were made by mixing additives and $sc-CO_2$ should form homogeneous and transparent phase (HTP) in order to effectively and uniformly remove the post etch/ash PR residue on the aluminum patterned wafer using them. The additives were formulated by mixing and co-solvents like an amine compound and fluorosurfactants used as HTP agents, and the PR residue on the wafer were able to be rapidly and effectively removed using the $sc-CO_2$ mixture of HTP. The five kinds of additives were formulated by the recipe of mixing co-solvents and surfactants, which were able to remove PR residue on the wafer by mixing with $sc-CO_2$ at the stripping temperature range from 40 to $80^{\circ}C$. The five kinds of $sc-CO_2$ mixtures which were named as PR removers were made, which were able to form HTP within the above described stripping temperature. The cloud points of $sc-CO_2$ mixtures were measured to find correlation between them and HTP.

• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4013-4021
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• 2022

A kind of zirconium phosphate mesoporous coordination polymer Zr-EDTMPA was successfully synthesized and characterized using XRD, FTIR, TGA, EA, SEM-EDS, and N₂ sorption-desorption measurements. The prepared Zr-EDTMPA was first employed for the removal of Co(II) from an aqueous solution, and the effects of pH, contact time, temperature, initial Co(II) concentration, reusability, and sorption mechanism were systematically investigated. The results showed that the Zr-EDTMPA is a zirconium phosphate complex formed by the coordination of EDTMPA to Zr in a molar ratio of 1:1. The sorption of Co(II) by Zr-EDTMPA was a pH-dependent, spontaneous and endothermic process, which was better fitted to the pseudo-second-order kinetic model and Langmuir isotherm model. The Zr-EDTMPA was demonstrated to have excellent reusability and presented a high sorption capacity of 73.0 mg·g^-1 for Co(II) at pH 8.0. The sorption mechanism was mainly attributed to the strong coordination between cobalt and the untapped hydroxyl functional groups on Zr-EDTMPA, which was confirmed by XPS spectra. Therefore, as a candidate sorbent with high sorption capacity and excellent reusability, Zr-EDTMPA has a great potential for the removal of Co(II) from aqueous solutions.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.6
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• pp.683-690
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• 2016

Modified coagulants were investigated for the removal of phosphorus from secondary effluent of wastewater treatment. The modified coagulants were prepared by mixing alkali earth metal ions such as calcium and magnesium. The basicity of a coagulant influenced on the removal of phosphorus, and coagulants with basicity of 5.9% showed a better removal of total phosphorus than that of 38.5%. Also, coagulants with alkali earth metals enhanced the performance of coagulation by 10% and resulted in 67.1% for total phosphorus removal. Moreover, the removal of suspended solids and chemical oxygen demand was improved using coagulants with low basicity and earth metal ions. Results of this study demonstrated that the use of coagulants with low basicity, and calcium and magnesium ions is recommended to improve wastewater effluent quality.

• Journal of Environmental Science International
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• v.28 no.8
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• pp.669-676
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• 2019

The purpose of this study was to evaluate the effects of different Hydraulic Retention Times (HRTs) on the contaminant removal efficiency using Aerobic Granular Sludge (AGS). A laboratory-scale experiment was performed using a sequencing batch reactor, and the Chemical Oxygen Demand (COD), nitrogen, orthophosphate removal efficiency, AGS/MLSS ratio, and precipitability in accordance with the HRT were evaluated. As a result, the COD removal efficiency was not significantly different with the reduction in HRT, and at a HRT of 6 h, the removal rate was slightly increased owing to the increase in organic loading rate. The nitrogen removal efficiency was improved by injection of influent division at a HRT of 6 h. As the HRT decreased, the MLSS and AGS tended to increase, and the sludge volume index finally decreased to 50 mL/g. In addition, the size of the AGS gradually increased to about 1.0 mm. Therefore, the control of HRT provides favorable conditions for the stable formation of AGS, and is expected to improve the contaminant removal efficiency with the selection of a proper operation strategy.

• Applied Chemistry for Engineering
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• v.16 no.5
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• pp.635-640
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• 2005

Mediated electrochemical oxidation (MEO) is an aqueous process which oxidizes organics electrochemicallly at low temperatures and pressures. The useful process can be used to treat mixed wastes containing hazardous organics. This paper have studied MEO of ethylene glycol (EG) in nitric acids by Fe(III)/Fe(II) and Co(III)/Co(II) system. It investigated current density, supporting electrolyte concentration, hydraulic retention time, removal efficiency of EG by MEO. Removal efficiency of EG by MEO was superior in Co(III)/Co(II) redox system than Fe(III)/Fe(II) redox system, where MEO removal efficiency was 100 percent. In case of EG, the reactions were fast and good yields of carbon dioxide formation was observed.