• Korean Journal of Plant Resources
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• v.24 no.3
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• pp.280-285
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• 2011

In this study, we established a novel somatic embryogenesis and plant regeneration system through cell suspension culture of white dandelion (Taraxacum coreanum NAKAI.). Embryogenic calli could be initiated from leaf and root explants of sterile seedlings on solid Murashige and Skoog (MS) medium supplemented with 1.0 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D) after 3-week cultures. To proliferate embryogenic calli rapidly, cell suspension culture was performed with transferred to liquid MS medium with various combinations of plant growth regulators (PGRs) including 2,4-D, ${\alpha}$-naphthalene acetic acid (NAA), indole-3-acetic acid (IAA), $N^6$-benzylamino purine (BAP), thidiazuron (TDZ), and kinetin. During suspension cultures, embryogenic calli not only greatly proliferated, but shoot organogenesis also simultaneously occurred from the surface of somatic embryos. Among them, TDZ at lower concentration, 0.1 mg/L produced the highest efficiency of somatic embryo formation and shoot organogenesis. Rooting of embryogenic calli with adventitious shoots was done on solid MS medium containing 0.1 mg/L NAA and 0.3% activated carbon. Nearly 80% of embryogenic calli with shoot organogenesis could be rooted normal. Well-rooted plantlets were transferred into pots under a greenhouse condition, and plants derived from this system appeared phenotypically normal.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.12
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• pp.1329-1336
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• 2007

This study was carried out to develop an efficient process abating high NO concentration. A hybrid process of selective catalytic reduction(SCR) and activated carbon fiber(ACF) adsorption was newly designed and tested. Used ACF in NO adsorption was regenerated by simultaneously applying heat and vacuum. The result of ACF regeneration was for superior in the desorption condition at $140^{\circ}C$ and vacuum 600 mmHg. A commercial catalyst was used at the conditions of reaction temperature at $300^{\circ}C$, $NH_3/NO$ mole ratio = 1.0 for SCR process. NO evolved from ACF regeneration reactor could be removed by SCR reactor up to 98%. But high concentration of NO was exhausted from SCR reactor for one minute when the flue gas of NO 300 ppm and deserted NO from ACF regeneration were simultaneously treated by the same SCR reactor. Therefore, it is necessary to use additional small sized SCR reactor or to increase $NH_3$ concentration for a short time along with NO concentration rather than to mix flue gas with the gas evolving from ACF regeneration at fixed $NH_3$ inlet concentration. The hybrid process of SCR and ACF showed high NO removal efficiency over 80% at any time courses. Through the repeated cycles, stable DeNOx efficiency was maintained, indicating that the hybrid process would be a good countermeasure to the spotaneously high NO concentration instead of increasing the SCR capacity.

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.527-534
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• 2012

The adsorption dynamics of activated carbon (AC) and carbon molecular sieve (CMS) beds were studied to recover ethylene from FCC fuel gas. In this study, the FCC fuel gas used consisted of six-component mixture ($CH_4/C_2H_4/C_2H_6/C_3H_6/N_2/H_2$,32:15:14:2:12:25 vol.%). And the breakthrough experiments of adsorption and desorption were carried out. The breakthrough sequence in the AC bed was $H_2$ < $N_2$ < $CH_4$ < $C_2H_4$ < $C_2H_6$ while the sequence in the CMS bed was $H_2$ < $CH_4$ < $N_2$ < $C_2H_6$ < $C_2H_4$. The separation performance of the CMS bed during the adsorption step was lower than that of the AC bed. However, due to the characteristics of kinetic separation, the CMS bed could remove $CH_4/N_2$ as well asthe molecules that are larger than $C_2H_6$, which was not easy to be done by the AC bed. Since it was hard to regenerate the adsorption bed by simple depressurization, vacuum regeneration should be adopted. As a result, the pressure vacuum swing adsorption (PVSA) process, consisting of CMS pretreatment process and AC main process, was suggested to recover ethylene efficiently.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.11
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• pp.1985-1994
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• 2000

This research was designed to investigate the effect of initial adsorbed amount of phenol, temperature, and pH on the desorption reaction of phenol from spent activated carbon loaded with phenol. Methanol, acetone, and N,N-dimethylformamide( DMF) were used as test organic solvents. The initial adsorbed quantities of phenol investigated here were 166.1mg/g, 180.7mg/g, and 197.9mg/g. The effect of temperature was evaluated from 15 to $55^{\circ}C$ with an interval of $10^{\circ}C$, while that of pH was investigated under acidic. neutral. and alkaline conditions. The extent of phenol desorption was proportional to the strength of dipole moment such as methanol < acetone < DMF. Over 90% desorption of phenol was achieved by acetone and DMF. The quantity of des orbed phenol by the organic solvents decreases with increasing the initial adsorbed amount of phenol. DMF is affected least by the initially adsorbed amount of phenol. An increase in reaction temperature leads to higher desorption of phenol. Desorption reaction by methanol is most sensitive to the temperature. As the pH of solvents increases. the desorption rate is also increasing. At pH=12. the desorption rate of phenol by methanol increases sharply by 10%. Although methanol demonstrated the weakest desorption power. the desorption capacity of methanol would approach that of acetone and DMF by adjusting temperature and pH. Methanol may emerge as a promising solvent for removing phenol from activated carbon because of acceptable regeneration efficiency as well as relatively cheap price.

• Clean Technology
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• v.12 no.4
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• pp.217-223
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• 2006

The operating variables of a desorption step were experimentally investigated tor the cycle of the process made up of benzene adsorption, steam desorption, and drying step. The effect of adsorbent regeneration depending on existence and nonexistence of drying step was studied by breakthrough curves obtained in the adsorption step of the second cycle. The duration of drying step was determined by the experimental results. In case that the amount of nitrogen gas was fixed, the regeneration efficiency increased with the amount of steam. However, the effect of steam decreased as the amount of nitrogen increased. Therefore, it would be possible to predict the optimum amount of steam comparing the amount of nitrogen gas with amount of steam in economic view.

• Journal of Korean Society on Water Environment
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• v.27 no.2
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• pp.167-177
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• 2011

Billions of barrels of briny produced water are generated in the United States every year during oil and gas production. The first step toward recovering or reusing this water is to remove the hazardous organics dissolved in the briny produced water. Biological degradation of hazardous volatile compound could be possible regardless of salinity if they were extracted from briny water. In the current work, the effectiveness of a vapor phase biofilter to degrade the gas-phase contaminants (benzene, toluene, ethylbenzene and xylenes, BTEX) extracted from briny produced water was evaluated. The performance of biofilter system responded well to short periods when the BTEX feed to the biofilter was discontinued. To challenge the system further, the biofilter was subjected to periodic spikes in inlet BTEX concentration as would be expected when it is coupled to a Surfactant-Modified Zeolite (SMZ) bed. Results of these experiments indicate that although the BTEX removal efficiency declined under these conditions, it stabilized at 75% overall removal even when the biofilter was provided with BTEX-contaminated air only 8 hours out of every 24 hours. Benzene removal was found to be the most sensitive to time varying loading conditions. A passive, granular activated carbon bed was effective at attenuating and normalizing the peak BTEX loadings during SMZ regeneration over a range of VOC loads. Field testing of a SMZ bed coupled with an activated carbon buffering/biofilter column verified that this system could be used to remove and ultimately biodegrade the dissolved BTEX constituents in briny produced water.

• Clean Technology
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• v.26 no.2
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• pp.137-144
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• 2020

Metal-impregnated activated carbons were prepared via ultrasonic-assisted impregnation method for regeneration and low ammonia concentration. Magnesium and copper were selected as metals, while chloride (Cl^-) and nitrate (NO₃^-) precursors were used to impregnate the surface of activated carbon. The physical and chemical properties of the prepared adsorbents were characterized by TGA, BET, and NH₃-TPD. The ammonia breakthrough test was carried out using a fixed bed and flowing ammonia gas (1000 mg L^-1 NH₃, balanced N₂) at 100 mL min^-1, under conditions of temperature swing adsorption (TSA) and pressure swing adsorption (PSA, 0.3, 0.5, 0.7, 0.9 Mpa). The adsorption and desorption performance of ammonia were in the order of AC-Mg(Cl) > AC-Cu(Cl) > AC-Mg(N) > AC-Cu(N) > AC through NH₃-TPD and TSA and PSA processes. AC-Mg(Cl) using MgCl₂ showed the average adsorption amount of 2.138 mmol/g at TSA process. Also, AC-Mg(Cl) showed the highest initial adsorption amount of 3.848 mmol/g at PSA 0.9 Mpa. When metal impregnated the surface of the activated carbon, it was confirmed that not only physical adsorption, but also chemical adsorption increased, making enhancement in adsorption and desorption performances possible. Also, the prepared adsorbents showed stable adsorption and desorption performances despite repeated processes, confirming their applicability in the TSA and PSA processes.

• Applied Chemistry for Engineering
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• v.33 no.2
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• pp.202-209
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• 2022

Effects of the support and amount of NiCl₂ on ammonia adsorption capacity were investigated to improve the ammonia adsorption performance. NiCl₂ was impregnated onto the surface of various supports under ultrasonic irradiation. The physicochemical properties and ammonia adsorption performance of NiCl₂-impregnated adsorbents were investigated. Among the various supports, it was found that the adsorption capacity of ammonia was the best when NiCl₂ was impregnated on activated carbon (AC) with the highest specific surface area. As a result of changing the amount of NiCl₂ impregnated on AC, the NiCl₂(2.0)/AC adsorbent impregnated with 2 mmol·g^-1 of NiCl₂ showed the highest ammonia adsorption capacity of 5.977 mmol·g^-1. In addition, the adsorption capacity was found to be maintained at an almost constant level in five repeated cycle tests under the condition that low-temperature heat could be utilized. This indicates that the adsorbent has excellent regeneration ability.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.1-6
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• 2021

Mercury, once released, is not destroyed but accumulates and circulates in the natural environment, causing serious harm to ecosystems and human health. In the United States, sulfur-impregnated activated carbon is being considered for the removal of vapor mercury from the flue gas of coal-fired power plants, which accounts for about 32 % of the anthropogenic emissions of mercury. In this study, a high-efficiency porous mercury adsorption material was developed to reduce the mercury vapor in the exhaust gas of coal combustion facilities, and the mercury adsorption characteristics of the material were investigated. As a result of the investigation of the vapor mercury adsorption capacity at 30℃, the silica nanotube MCM-41 was only about 35 % compared to the activated carbon Darco FGD commercially used for mercury adsorption, but it increased to 133 % when impregnated with 1.5 % sulfur. In addition, the furnace fly ash recovered from the waste copper regeneration process showed an efficiency of 523 %. Furthermore, the adsorption capacity was investigated at temperatures of 30 ℃, 80 ℃, and 120 ℃, and the best adsorption performance was found to be 80 ℃. MCM-41 is a silica nanotube that can be reused many times due to its rigid structure and has additional advantages, including no possibility of fire due to the formation of hot spots, which is a concern when using activated carbon.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.4
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• pp.481-491
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• 2022

This study investigates the characteristics of the GAC adsorption behavior during the operation of a multi-stage cross-flow filtration and GAC adsorption process for the purpose of devising an advanced treatment of combined sewer overflows (CSOs) and evaluates the regeneration efficiency of spent GAC that has reached the design breakpoint. During the filtration process, suspended substances are easily removed, but dissolved organic substances are not removed, necessitating a process capable of removing dissolved organic substances for the advanced treatment of CSOs. In general, GAC adsorption has been applied under low-concentration organic conditions, such as for water purification and tertiary treatments of sewage, and has rarely been applied under conditions with high organic concentrations, such as with sewage or CSOs. Accordingly, this study will provide a new and interesting experience. Also in this study, the continuous operation and breakthrough characteristics of GAC according to the strength of the inflow organic matter were investigated, electrochemical regeneration was applied to the used GAC, and the regeneration efficiency was evaluated through desorption and re-adsorption tests. The results showed that the breakthrough period was 21 days under high concentration conditions, 28 days at medium concentrations, and 32 days under low concentration conditions. The desorption of adsorbed organic matter through electrolysis occurred in the range of 188 to 609 mgCOD/L depending on the electrolysis conditions, and the effect of the electrolyte type led to the finding that NaOH was slightly higher than H₂O₂.