• Journal of Korean Society of Environmental Engineers
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• v.27 no.12
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• pp.1347-1352
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• 2005

[ $H_2S$ ] removal reaction using $Li_2ZrO_3/honeycomb$ has been carried out in a fixed bed reactor for the cleaning of syngas from the waste gasifier. $Li_2ZrO_3$ was synthesised using reagent-grade $Li_3CO_3$ and $ZrO_2$ with suitable amount of ethanol in a 1:1 ratio. And then $Li_2ZrO_3$ were calcined in air at $850{\sim}1000^{\circ}C$ for 14 h. The optimum condition of $H_2S$ removal reaction is around 20 wt% $Li_2ZrO_3$/honeycomb at 300 mL/min and $700^{\circ}C$. At this condition, removal amount of $H_2S$ was about 0.337 $g^{H_2S}/g^{sorbent}$. Addition of $K_2CO_3$, $Na_2CO_3$, NaCl and LiCl in the $Li_2ZrO_3$ remarkably improves the $H_2S$ removal capacity of modified $Li_2ZrO_3$/honeycomb up to 23%. Analyses of $Li_2ZrO_3/honeycomb$ sorbent by SEM and XRD showed that $Li_2ZrO_3$ was uniformly impregnated into honeycomb up to considerable amounts. Furthermore, the physicochemical properties of the sorbent did not vary much up to $1000^{\circ}C$.

• Applied Chemistry for Engineering
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• v.10 no.4
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• pp.557-562
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• 1999

The reaction properties of Pd. Pd-Ce and Pd-La catalysts supported on ${\gamma}-Al_2O_3$ were investigated in the oxidation reaction of methane($CH_4$) exhausted from the compressed natural gas vehicle in a U-tube flow reactor with gas hourly space velocity of $72,000h^{-1}$. The catalysts were characterized by X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), BET surface area and hydrogen chemisorption. Pd catalyst prepared by $Pd(NO_3)_2$ as a palladium precursor and calcined at $600^{\circ}C$ showed the highest activity for a methane oxidation. Catalytic activity of calcined $Pd/{\gamma}-Al_2O_3$ in which most of palladium was converted into palladium oxide species was higher than that of reduced $Pd/{\gamma}-Al_2O_3$ in which most of palladium existed in palladium metal by XRD. As increasing the number of reaction cycles in the wide range of redox, the catalytic activity of $Pd/{\gamma}-Al_2O_3$ was decreased and the highly active window became narrower. Lanthanum oxide promoted Pd catalyst, $Pd/La/{\gamma}-Al_2O_3$ showed enhanced thermal stability compared with $Pd/{\gamma}-Al_2O_3$ even after aging at $1000^{\circ}C$, which was ascribed to the role of La as a promoter to suppress the sintering of palladium metal and ${\gamma}-Al_2O_3$ support. Almost all of methane was removed by the reaction with NO at the redox ratio of 1.2 in case of oxygen excluded steam, but that activity was significantly decreased in the steam containing oxygen.

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.988-993
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• 2008

The characteristics of NO oxidation using sodium chlorite ($NaClO_2$) powder have been investigated by a flow type packed-bed reactor, where the reaction temperature and the space velocity are varied in the range of $20{\sim}230^{\circ}C$ and $0.4-2.2{\times}10^5hr^{-1}$, respectively, and the simulation gas mixtures are composed of NO (0~200 ppm), $NO_2$ (0-200 ppm), $O_2$ (0~15%) and $H_2O$ (0~15%) within $N_2$ balance. It has been found that the oxidation efficiency of NO depends greatly on the reaction temperature, exhibiting the existence of critical reaction temperature at about $170^{\circ}C$ where the oxidation efficiency of NO is maximized and then abruptly decreased with further increase of reaction temperature, resulting in being negligible over $190^{\circ}C$. Such a behavior in the oxidation efficiency has been originated from the phase transition of $NaClO_2$ at about $170^{\circ}C$ to form $NaClO_3$, and NaCl which are chemically inactive toward the oxidation of NO. The chemical reaction of NO with $NaClO_2$ has been observed to produce $NO_2$, ClNO and $ClNO_2$, whereas that of $NO_2$ only OClO species. Additionally, we have also observed that the introduction of $O_2$ and $H_2O$ has little influence on the oxidation of NO.

• Clean Technology
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• v.20 no.4
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• pp.375-382
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• 2014

This work investigated the plasma-catalytic decomposition of isopropyl alcohol (IPA) and the behavior of the byproduct compounds over monolith-supported metal oxide catalysts. Iron oxide ($Fe_2O_3$) or copper oxide (CuO) was loaded on a monolithic porous ${\alpha}-Al_2O_3$ support, which was placed inside the coaxial electrodes of plasma reactor. The IPA decomposition efficiency itself hardly depended on the presence and type of metal oxides because the rate of plasma-induced decomposition was so fast, but the behavior of byproduct formation was largely affected by them. The concentrations of the unwanted byproducts, including acetone, formaldehyde, acetaldehyde, methane, carbon monoxide, etc., were in order of $Fe_2O_3/{\alpha}-Al_2O_3$ < $CuO/{\alpha}-Al_2O_3$ < ${\alpha}-Al_2O_3$ from low to high. Under the condition (flow rate: $1L\;min^{-1}$; IPA concentration: 5,000 ppm; $O_2$ content: 10%; discharge power: 47 W), the selectivity towards $CO_2$ was about 40, 80 and 95% for ${\alpha}-Al_2O_3$, $CuO/{\alpha}-Al_2O_3$ and $Fe_2O_3/{\alpha}-Al_2O_3$, respectively, indicating that $Fe_2O_3/{\alpha}-Al_2O_3$ is the most effective for plasma-catalytic oxidation of IPA. Unlike plasma-alone processes in which tar-like products formed from volatile organic compounds are deposited, the present plasma-catalyst hybrid system did not exhibit such a phenomenon, thus retaining the original catalytic activity.

• Korean Chemical Engineering Research
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• v.51 no.3
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• pp.313-318
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• 2013

In order to investigate the effect of $V_2O_5$ loading of $V_2O_5-WO_3/TiO_2$ catalyst on the NO reduction and the formation of $N_2O$, the experimental study was carried out in a differential reactor using the powder catalyst. The NO reduction and the ammonia oxidation were, respectively, investigated over the catalysts compose of $V_2O_5$ content (1~8 wt%) based on the fixed composition of $WO_3$ (9 wt%) on $TiO_2$ powder. $V_2O_5-WO_3/TiO_2$ catalysts had the NO reduction activity even under the temperature of $200^{\circ}C$. However, the lowest temperature for NO reduction activity more than 99.9% to treat NO concentration of 700 ppm appeared at 340 with very limited temperature window in the case of 1 wt% $V_2O_5$ catalyst. And the temperature shifted to lower one as well as the temperature window was widen as the $V_2O_5$ content of the catalyst increased, and finally reached at the activation temperature ranged $220{\sim}340^{\circ}C$ in the case of 6 wt% $V_2O_5$ catalyst. The catalyst of 8 wt% $V_2O_5$ content presented lower activity than that of 8 wt% $V_2O_5$ content over the full temperature range. NO reduction activity decreased as the $V_2O_5$ content of the catalyst increased above $340^{\circ}C$. The active site for NO reduction over $V_2O_5-WO_3/TiO_2$ catalysts was mainly related with $V_2O_5$ particles sustained as the bare surface with relevant size which should be not so large to stimulate $N_2O$ formation at high temperature over $320^{\circ}C$ according to the ammonia oxidation. Currently, $V_2O_5-WO_3/TiO_2$ catalysts were operated in the temperature ranged $350{\sim}450^{\circ}C$ to treat NOx in the effluent gas of industrial plants. However, in order to save the energy and to reduce the secondary pollutant $N_2O$ in the high temperature process, the using of $V_2O_5-WO_3/TiO_2$ catalyst of content $V_2O_5$ was recommended as the low temperature catalyst which was suitable for low temperature operation ranged $250{\sim}320^{\circ}C$.

• Clean Technology
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• v.27 no.1
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• pp.9-16
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• 2021

Since the active matrix organic light-emitting diode (AMOLED) encapsulation process is very vulnerable to moisture and oxygen, high-purity nitrogen with minimal moisture and oxygen must be used. In this study, a copper-based catalyst used to remove oxygen from nitrogen in the AMOLED encapsulation process was optimized. Two-component and three-component catalysts composed of CuO, Al2O3, or ZnO were prepared through a co-precipitation method. The prepared catalysts were characterized by using BET, XRD, TPR, and XRF analysis. In order to verify the oxygen removal performance of the catalyst, several catalytic reactions were conducted in a fixed bed reactor, and the corresponding oxygen contents were measured through an oxygen analyzer. In addition, reusability of the catalysts was proven through repetitive regeneration. The properties and oxygen removal capacity of the catalysts prepared with CuO and Al2O3 ratios of 6 : 4, 7 : 3, and 8 : 2 were compared. The number of active sites of the catalyst with a ratio of CuO and Al2O3 of 8 : 2 was the highest among the 2-component catalysts. Moreover, the reducibility of the catalyst with a ratio of CuO and Al2O3 of 8 : 2 was the best as it had the highest CuO dispersion. As a result, the oxygen removal ability of the catalyst with a ratio of CuO and Al2O3 of 8 : 2 was the best among the 2-component catalysts. The best oxygen removal capacity was obtained when 2wt% of ZnO was added to the sub-optimized catalyst (i.e., CuO : Al2O3 = 8 : 2) probably due to its outstanding reducibility. Furthermore, the optimized catalyst kept its performance during a couple of regeneration tests.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.5
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• pp.500-506
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• 2008

Enhanced phytoremediation with EDTA or PSM(Phosphate solubilizing microorganism) was studied using green foxtail (Setaria viridis) in columns packed with 1,200 mgPb/kg contaminated soil to investigate the effects of EDTA or PSM on the plant uptake and vertical migration of Pb. EDTA, equimolar amount of total Pb in the column soil, was administered in two methods: the one was treated with 1/6 aliquots of the equimolar EDTA every week for 6 weeks and the other was treated with single dose of the equimolar EDTA before 14 days of harvest. The results showed that higher concentrations of Pb accumulated in the biomass of green fowtail after the chemical or biological treatment. The plant-root Pb concentration in PSM treatment(M), EDTA aliquot treatment(ES), and single dose treatment(E) was 2.6, 3.0, and 3.3 times higher, respectively, than that in the plant-root of control(164.7 mg/kg). The plant-stem Pb concentration in the M, ES and E treatment was 27, 37, and 40 times higher than that in the stem of control(8.1 mg/kg). The translocation factor, the ratio of shoot/root Pb concentration, was 0.6 in the two EDTA treatment, 0.5 in the M treatment, and 0.05 in the control, respectively. The largest amount of Pb was phyto-extracted in the E treatment whereas vertical migration of EDTA was significant in the ES treatment. This result showed that a single large dose of EDTA before harvest serves better for enhanced phytoremediation of Pb. Although, treatment with PSM showed less Pb phytoextraction by the plant but enhanced both the growth of plants in the column and microbial dehydrogenase activity in the soils. Therefore, enhanced phytoextraction of Pb with PSM treatment can be an alternative option for EDTA treatment, which is toxic to plants and soil ecosystem.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.9
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• pp.961-972
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• 2008

In 2004, total emissions of Greenhouse Gases(GHGs) in Korea was estimated to be about 590 million metric tons, which is the world's 10th largest emissions. Considering the much amount of nation's GHG emissions and growing nation's position in the world, GHG emissions in Korea should be reduced in near future. The CO$_2$ emissions from two sub-sections of energy sector in Korea, such as thermal power plant and industry section(including manufacturing and construction industries), was about 300 million metric tons in 2004 and this is 53.3% of total GHG emissions in Korea. So, the mitigation of CO$_2$ emissions in these two section is more important and more effective to reduce the nation's total GHGs than any other fields. In addition, these two section have high potential to qualitatively and effectively apply the CCS(Carbon Capture and Storage) technologies due to the nature of their process. There are several CCS technologies applied to these two section. In short term, the chemical absorption technology using amine as a absorbent could be the most effectively used. In middle or long term, pre-combustion technology equipped with ATR(Autothermal reforming), or MSR-$H_2$(Methane steam reformer with hydrogen separation membrane reactor) unit and oxyfuel combustion such as SOFC+GT(Solid oxide fuel cell-Gas turbine) process would be the promising technologies to reduce the CO$_2$ emissions in two areas. It is expected that these advanced CCS technologies can reduce the CO$_2$ avoidance cost to $US 8.5-43.5/tCO$_2$. Using the CCS technologies, if the CO$_2$ emissions from two sub-sections of energy sector could be reduced to even 10% of total emissions, the amount of 30 million metric tons of CO$_2$ could be mitigated.

• Journal of the Korea Organic Resources Recycling Association
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• v.28 no.1
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• pp.53-64
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• 2020

A 2㎥/d combined wastewater treatment pilot plant containing the multi-stage vertical stacking type nitrification reactor was installed and operated for more than 1 year under the operating conditions of the short-circuit nitrogen process (pH 8, DO 1mg/L and Internal return rate 4Q from nitrification to denitrification reactor). For economically the combination treatment of food wastewater and the leachate from a landfill, the optimal combination ratio was operated by adjusting the food wastewater with the minimum oil content to 5-25% of the total throughput. The main treatment efficiency of the three-phase centrifugal separator which was introduced to effectively separate solids and oil from the food wastewater was about 52% of SS from 116,000mg/L to 55,700mg/L, and about 48% of normal hexane (NH) from 53,200mg to 27,800 mg/L. During the operational period, the average removal efficiency in the combined wastewater treatment process of BOD was 99.3%, CODcr 94.2%, CODmn 90%, SS 70.1%, T-N 85.8%, and T-P 99.2%. The average concentrations of BOD, CODcr, T-N, and T-P of the treated water were all satisfied with the discharge quality standard for landfill leachate ("Na" region), and SS was satisfied after applying the membrane process. On-site leachate had a relatively high nitrite nitrogen content in the combined wastewater due to intermittent aeration of the equalization tanks and different monthly discharges. Nevertheless nitrite nitrogen was accumulated, denitrification from nitrite nitrogen was observed rather than denitrification after complete nitrification. The average input of anti-forming chemical during the operation period is about 2L/d, which seems to be economical compared to the input of methanol required to treat the same wastewater.

• Economic and Environmental Geology
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• v.43 no.2
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• pp.123-136
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• 2010

In order to remediate heavy metal contaminated Nong island, Maehyang-ri shooting range soils through the batch reactor scale washing were evaluated. The experiment texture soil of N3 in the Nong island at north side incline was (g)mS containing 12.9% gravel, 47.0% sand, 35.1% silt and 5.0% clay. And the N3 soil area was contaminated with Cd($22.5\pm1.9$ ppm), Cu($35.5\pm4.0$ ppm), Pb($1,279.0\pm5.1$ ppm) and Zn($403.4\pm9.8$ ppm). The EDTA(ethylene diamine tetra acetic acid, $C_{10}H_{16}N_2O_8$) in the N3 soil was observed as most effective extractants among the 5 extractants(citric acid, EDTA, phosphoric acid, potassium phosphate and oxalic acid) tested. And chemical partitioning of heavy metals after washing N3 soil with EDTA was evaluated. Removal efficiency of residual fractions was higher than that of non-residual fractions. To choose EDTA extractant which is the most effective in soil washing technology using batch reactor process cleaning Pb and Zn contaminated sits; Pb and Zn removal rates were investigated 92.4%, 94.0% removal(1,000 mM, soil:solution=5, $20^{\circ}C$, 24 hour shaking, pH=2, 200 RPM), respectively. The results of the batch test showed that the removal efficiency curve was logarithmic in soil was removal. Thus, EDTA washing process can be applied to remediate the Pb and Zn contaminated soil used in this study.