• Korean Journal of Soil Science and Fertilizer
• /
• v.49 no.1
• /
• pp.30-35
• /
• 2016

Rice cultivation in paddy field affects the global balance of methane ($CH_4$) as a key greenhouse gas. To evaluate a potential use of by-product gypsum fertilizer (BGF) in reducing $CH_4$ emission from paddy soil, $CH_4$ fluxes from a paddy soil applied with BGF different levels (0, 2, 4 and $8Mg\;ha^{-1}$) were investigated by closed-chamber method during rice cultivation period. $CH_4$ flux significantly decreased (p<0.05) with increasing level of BGF application. $8Mg\;ha^{-1}$ of BGF addition in soil reduced $CH_4$ flux by 60.6% compared to control. Decreased soil redox potential (Eh) resulted in increasing $CH_4$ emission through a $CO_2$ reduction reaction. The concentrations of dissolved calcium (Ca) and sulfate ion (${SO_4}^{2-}$) in soil pore water were significantly increased as the application rate of BGF increased and showed negatively correlations with $CH_4$ flux. Decreased $CH_4$ flux with BGF application implied that ${SO_4}^{2-}$ ion led to decreases in electron availability for methanogen and precipitation reaction of Ca ion with inorganic carbon including carbonate and bicarbonate as a source of $CH_4$ formation under anoxic condition. BGF application also increased rice grain yield by 16% at $8Mg\;ha^{-1}$ of BGF addition. Therefore, our results suggest that BGF application can be a good soil management practice to reduce $CH_4$ emission from paddy soil and to increase rice yield.

• Journal of Microbiology and Biotechnology
• /
• v.25 no.4
• /
• pp.452-458
• /
• 2015

The biocatalytic efficiency of recombinant Corynebacterium glutamicum ATCC 13032 expressing the secondary alcohol dehydrogenase of Micrococcus luteus NCTC2665 was studied. Recombinant C. glutamicum converts ricinoleic acid to a product, identified by gas chromatography/mass spectrometry as 12-ketooleic acid (12-oxo-cis-9-octadecenoic acid). The effects of pH, reaction temperature, and non-ionic detergent on recombinant C. glutamiucm whole cell bioconversion were examined. The determined optimal conditions for production of 12-ketooleic acid are pH 8.0, 35℃, and 0.05 g/l Tween80. Under these conditions, recombinant C. glutamicum produces 3.3 mM 12-ketooleic acid, with a 72% (mol/mol) maximum conversion yield, and 1.1 g/l/h volumetric productivity in 2 h; and 3.9 mM 12-ketooleic acid, with a 74% (mol/mol) maximum conversion yield, and 0.69 g/l/h maximum volumetric productivity in 4 h of fermentation. This study constitutes the first report of significant production of 12-ketooleic acid using a recombinant Corynebacterium glutamicum-based biocatalyst.

• 한국생물공학회:학술대회논문집
• /
• 2003.10a
• /
• pp.422-427
• /
• 2003

Rhodopseudomonas palustris P4 can produce $H_2$ either from CO by water-gas shift reaction or from various sugars by anaerobic fermentation. Fermentative $H_2$ production by P4 is fast, but its yield is relatively low due to the formation of various organic acids. In order to increase $H_2$ production yield from glucose, P4 was investigated for the photo-fermentation of acetate which is a major by-product of fermentative $H_2$ production. Experiments were performed in batch modes using both light-grown and dark-grown cells. When the dark-grown P4 was challenged with light and acetate, $H_2$ was produced with the consumption of acetate after a lag period of 25 h. $H_2$ production was inhibited when a nitrogen source, especially ammonium, is present. When the dark-fermentation broth containing acetate was adopted for photo-fermentation with light-grown cells, $H_2$ production and concomitant acetate consumption occurred without a lag period. The $H_2$ yield was estimated as 2.4 - 2.8 mol $H_2/mol$ acetate and the specific $H_2$ production rate was as 9.8 ml $H_2/g$ cell${\cdot}$h, The fact that a single strain can perform both dark- and light-fermentation gives a great advantage in process development Compared to a one-step dark-fermentation, the combined dark- and light-fermentation can increase the $H_2$ production yield on glucose by two-fold.

• Proceedings of the Korean Institute of Resources Recycling Conference
• /
• 2005.10a
• /
• pp.75-82
• /
• 2005

Pyrolysis of biomass is one of the promising methods to obtain energy and valuable chemical stocks. Fast pyrolysis of Q. acutissima and L. letolepis has been carried out in a bubbling fluidized bed reactor to determine the optimum operating conditions of the pyrolyzer. Effects of reaction temperature, Uo/Umf, L/D ratio, and feed rate have been determined and the optimum conditions are as follows: $T\;=\;400^{\circ}C,\;U_o/U_{mf}\;=\;3.0,\;L/D\;=\;2.0$. Maximum yield of bio-oil was about 55% and the main compositions were carbohydrates, guaiacols, furans, phenols, and syringols. Product gas was consists of CO, $CO_2$, light hydrocarbons and the measured gas yield using the compositions agreed with the calculated value.

• Journal of Korean Society for Atmospheric Environment
• /
• v.18 no.E2
• /
• pp.107-120
• /
• 2002

Dimethyl sulfide (DMS) is the major sulfur gas released from the ocean. The atmospheric DMS released from the ocean is oxidized mainly by hydroxyl (OH) radical during the day and nitrate (NO$_3$) radical at night to form sulfur dioxide (SO$_2$) as well as other stable products. The oxidation mechanism of DMS via OH has been known to proceed by two channels; abstraction and addition channels. The major intermediate product of the addition channel has been known to be dimethylsulfoxide (DMSO) based on laboratory chamber studies and field experiments. However, a branching ratio for DMSO formation is still uncertain. The reaction of DMSO with OH ultimately produces SO$_2$and dimethylsulfone. The major product of the abstraction channel has known to be SO$_2$from laboratory chamber studies. But overall conversion efficiency for DMS to SO$_2$from DMS oxidation is still inconsistent in the literature. Based on laboratory and field studies, the conversion efficiency from the abstraction channel is likely to be greater than 0.5, while that from the addition channel is likely to be greater than 0.6. Overall conversion efficiency from DMS to SO$_2$might be greater than 0.5 based on the above two values in the remote marine boundary layer (MBL). This high efficiency in the remote MBL is supported by strong coupling between DMS and SO$_2$measurements with high temporal resolution.

• Journal of the Korean Society of Combustion
• /
• v.14 no.2
• /
• pp.1-9
• /
• 2009

New way to effectively capture $CO_2$ in coal fired power plant is the combustion of coal using oxy-fuel technology. Combustion characteristics of Minco sub-bituminous coal at oxy-fuel conditions using TGA and drop tube furnace (DTF) were included activation energy about the char burnout, volatile yield and combustion efficiency of raw coal, the porosity of pyrolyzed char and fusion temperature of by-product ash. TGA result shows that the effect of $CO_2$ on combustion kinetics reduces activation energy by approximately 7 kJ/mol at air oxygen level(21% $O_2$) and decreases the burning time by approximately 16%. The results from DTF indicated similar combustion efficiency under $O_2/CO_2$ and $O_2/N_2$ atmospheres for equivalent $O_2$ concentration whereas high combustion efficiency under $O_2/N_2$ than $O_2/CO_2$ was obtained for high temperature of more than $1,100^{\circ}C$. Overall coal burning rate under $O_2/CO_2$ is decreased due to the lower rate of oxygen diffusion into coal surface through the $CO_2$ rich boundary layer. By-product ash produced under $O_2/CO_2$ and $O_2/N_2$ was similar IDT in irrelevant to $O_2$ concentration and atmospheres gas during the coal combustion.

• Journal of the Korean Wood Science and Technology
• /
• v.19 no.4
• /
• pp.80-84
• /
• 1991

Lignocellulosic biomass including acetosolv ricestraw and spruce lignin were liquefied and converted into liquid hydrocarbons by catalytic hydroliquefaction reaction. These experimental works were carried out in 1-liter-capacity autoclave using 50% tetralin and m-cresol solution respectively as soluble solvent and Ni. Pd. Fe and red mud as catalyst. $H_2$ gas was supplied into the reactor for escaltion of deoxhydroenolysis reaction. Catalyst concentrations were 1 % of raw material based on weight. The ratio between raw materials and soluble solvent are 1g and 10cc. The reaction conditions are 400-$700^{\circ}C$ of reaction temperature, 10-50 atms of reaction pressure. The highest yield of hydrocarbon, so called "product oil" showed 32% and 5.5% of lowest char formation when red mud was used as catalyst. The product oil yields from those of other catalysts were in the range of 20-29%. The influence of different initial hydrogen pressures was examined in the range d 30-50 atms. A minimum pressure of 35 atms was necessary to obtain a complete recovery of souble solvent for recycling.

• Journal of Hydrogen and New Energy
• /
• v.14 no.2
• /
• pp.105-113
• /
• 2003

The pyrolysis for production of hydrogen and high quality carbon black from natural gas were studied. The reactivities in tubular reactor and FVR(free volume reactor) for the methane pyrolysis were compared, in order to prevent the formation of undesirable carbon product such as pyrocarbon, the FVR was designed. The hydrogen yield and the formation of carbon black from methane pyrolysis in this reactor were investigated at temperature range between 1443 and 1576K. From the result of TEM (transmission electron microscopy) analysis, it was confirmed that the CFC(catalytic filamentous carbon) was formed without pyrocarbon.

• Journal of the Korean Applied Science and Technology
• /
• v.35 no.3
• /
• pp.865-875
• /
• 2018

Selection of optimum reaction conditions during deoxygenation process of palm oil is essential factor to obtain the maximum yield of bio-jet fuel. In this context, the deoxygenation of palm oil was carried out in a fixed bed reactor with an internal diameter of 1 inch loaded with a 1 wt.% $Pt/Al_2O_3$ catalyst. The composition of the organic liquid product(OLP), which can be utilized as a transportation fuel through the upgrading process, was analyzed by a gas chromatography method. The palm oil/hydrogen ratio and hydrogen pressure in the feed affected the decarboxylation(DCB) and hydrodeoxygenation(HDO) reactions, resulting in a change in the composition of the OLP. As the reaction temperature increased, the continuous cracking reaction of the deoxygenation product was promoted and the product composition in the $C_5{\sim}C_{14}$ region was increased. Thus, the results can help to understand the characteristics of deoxidation reaction of palm oil as well as the subsequent process, hydro-upgrading, to obtain the maximum yield of bio-jet fuel.

• Applied Chemistry for Engineering
• /
• v.16 no.2
• /
• pp.296-303
• /
• 2005

The co-pyrolysis characteristics of polyvinylchloride (PVC) and acrylonitrile butadiene styrene (ABS) mixtures with various mixing ratios and effect of addition of CaO and $Cu_2O$ have been studied using thermogravimetry (TG) and gas chromatograph-mass spectrometry (GC-MS). In an isothermal decomposition conducted at $500^{\circ}C$, the yields of styrene monomers and aromatic compounds increased as the mixing ratio of ABS increased, and the yield of BTX compounds reached its maximum (16.14%) when the mixing ratios of PVC and ABS was 4:1. In an isothermal decomposition added with metal oxides, the maximum yield of liquid product was 73% when CaO [CaO/(PVC+ABS)=0.4] was added and it was 70% when $Cu_2O$ [$Cu_2O$/(PVC+ABS)=0.4] was added, respectively, where HCl contained in the gaseous product was completely removed when added with CaO [CaO/(PVC+ABS)=0.5] and $Cu_2O$ [$Cu_2O$/(PVC+ABS)=1.0]. Therefore, to obtain the highest yield of liquid product it appears to be the reaction condition: the reaction temperature of $500^{\circ}C$ and mixing ratios of CaO and $Cu_2O$ are 0.5 and 1.0, respectively.