• Transactions of the Korean hydrogen and new energy society
• /
• v.27 no.1
• /
• pp.13-21
• /
• 2016

The Sulfur-Iodine thermochemical hydrogen production process (SI process) consists of the Bunsen reaction section, the $H_2SO_4$ decomposition section, and the HI decomposition section. The $HI_x$ solution ($I_2-HI-H_2O$) could be recycled to Bunsen reaction section from the HI decomposition section in the operation of the integrated SI process. The phase separation characteristic of the Bunsen reaction using the $HI_x$ solution was similar to that of $I_2-H_2O-SO_2$ system. On the other hands, the amount of produced $H_2SO_4$ phase was small. To investigate the effects of $SO_2$ solubility on Bunsen reaction, the continuous Bunsen reaction was performed at variation of the amounts of $SO_2$ gas. Also, it was carried out to make sure of the effects of partial pressure of $SO_2$ in the condition of 3bar of $SO_2-O_2$ atmosphere. As the results, the characteristic of Bunsen reaction was improved with increasing the amounts and solubility of $SO_2$ gas. The concentration of Bunsen products was changed by reverse Bunsen reaction and evaporation of HI after 12 h.

• Journal of Korean Society of Water and Wastewater
• /
• v.30 no.2
• /
• pp.167-177
• /
• 2016

This work investigated the decomposition of aqueous anatoxin-a originated from cyanobacteria using an underwater dielectric barrier discharge plasma system based on a porous ceramic tube and an alternating current (AC) high voltage. Plasmatic gas generated inside the porous ceramic tube was uniformly dispersed in the form of numerous bubbles into the aqueous solution through the micro-pores of the ceramic tube, which allowed an effective contact between the plasmatic gas and the aqueous anatoxin-a solution. Effect of applied voltage, treatment time and the coexistence of nutrients such as $NO_3{^-}$, $H_2PO_4{^-}$ and glucose on the decomposition of anatoxin-a was examined. Chemical analyses of the plasma-treated anatoxin-a solution using liquid chromatography-mass spectrometry (LC-MS) and ion chromatography (IC) were performed to elucidate the mineralization mechanisms. Increasing the voltage improved the anatoxin-a decomposition efficiency due to the increased discharge power, but the energy required to remove a given amount of anatoxin-a was similar, regardless of the voltage. At an applied voltage of 17.2 kV (oxygen flow rate: $1.0L\;min^{-1}$), anatoxin-a at an initial concentration of $1mg\;L^{-1}$ (volume: 0.5 L) was successfully treated within 3 min. The chemical analyses using LC-MS and IC suggested that the intermediates with molecular weights of 123~161 produced by the attack of plasma-induced reactive species on anatoxin-a molecule were further oxidized to stable compounds such as acetic acid, formic acid and oxalic acid.

• Applied Chemistry for Engineering
• /
• v.23 no.6
• /
• pp.608-613
• /
• 2012

Dielectric barrier discharge plasma reactor was applied to the removal of ethylene from a simulated storage facility ($1.0m^3$) of fruits and vegetables. The system operated in a closed-loop mode by feeding the contaminated gas to the plasma reactor and recirculating the treated gas back to the storage facility. The experiments were carried out with parameters such as discharge power, circulation flow rate, initial ethylene concentration and treatment time. The rate of ethylene decomposition was mainly controlled by the discharge power and the treatment time. With the other conditions kept constant, the ethylene decomposition rate in the presence of the manganese oxide ozone control catalyst installed downstream from the plasma reactor was lower than that in the absence of it. The suggests that unreacted ozone from the plasma reactor accumulated in the storage facility where it additionally decomposed ethylene. On the basis of an initial ethylene concentration of 50 ppm, the energy requirement for completing the decomposition was about 60 kJ.

• Journal of the Korean Institute of Gas
• /
• v.26 no.5
• /
• pp.41-48
• /
• 2022

2-Chloro-N-(Cyano-2-thienyl methyl) acetamide (CCTA) is an intermediate used for synthesizing pesticides. It is stable at room temperature and pressure but can be decomposed when heat is accumulated. In this study, the decomposition characteristics were evaluated by measuring the weight change according to temperature using a Thermogravimetry analyzer(TGA), and the thermal decomposition characteristics were evaluated using Differential Scanning Calorimeter(DSC). The exothermic decomposition reaction occurred rapidly at about 91 ℃, and the activation energy determined by using Kissinger method, Kissinger-Akahira-Sunose(KAS) method, and Flynn-Wall-Ozawa(FWO) method were 162 kJ/mol, 149 kJ/mol and 139 kJ/mol, respectively. T_D24, the temperature at which the maximum heating rate is reached within 24 hours, was evaluated as 52~55 ℃ using the estimated activation energy.

• Journal of the Korean Ceramic Society
• /
• v.41 no.5
• /
• pp.410-416
• /
• 2004

In this study, we fabricated magnetite coated on a cordierite honeycomb which has complex shape by ultrasound-enhanced ferrite plating. The effects of the plating condition on the formation of the magnetite and its microstructure were investigated. The magnetite coated on the honeycomb became an oxygen-deficient ferrite by H$_2$ gas reduction, then the effects of the molar concentrations of ammonium acetate for $CO_2$ gas decomposition have been studied. As the molar concentration of a pH buffer($CH_3$COONH$_4$, 0.1946∼0.3892 M) solution increased, the average particle size increased about 200∼250 nm. The magnetite coated on the honeycomb was reduced by H$_2$ gas for 2 h at 30$0^{\circ}C$. The inner pressure change in the cell began to occur at 315∼34$0^{\circ}C$. The H$_2$-Reduced magnetite coated on the honeycomb at 35$0^{\circ}C$ contained an oxygen deficient magnetite and $\alpha$-Fe phase. The thermogravimetric analysis with H$_2$ reduction and $CO_2$ decomposition were carried out with the magnetite coated on the honeycomb. A weight loss in process of H$_2$ reduction occurred between 32$0^{\circ}C$ and 34$0^{\circ}C$, while a weight gain was observed during the $CO_2$ decomposition.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.2
• /
• pp.1375-1380
• /
• 2015

Nowadays, the technique to deal with the waste gas of perfluorinated compounds using plasma has been developed. As the effective decomposition techniques at many research centers and companies were investigated at home and abroad, the products have been improved with various methods. This study aims to guess the distributions of pressure and temperature through the thermal and fluid analyses inside the decomposition equipment model of waste gas. As the analysis result, the maximum pressure and the minimum pressure are 0.975Pa and -1.037Pa individually on the whole. It is shown that the pressure of air decreases gradually as the air flows from inlet to plane 1 and the pressure increases as the air flows from plane 1 to outlet. And the maximum temperature and the mimum temperature are $1718^{\circ}C$와 $26.07^{\circ}C$ individually on the whole. It is shown that the temperature of air increases gradually as the air flows from inlet to plane 4 and the temperature decreases as the air flows until outlet. It is thought that the data necessary to develop the real system can be applied by using the thermal and fluid analyses.

• Journal of the Korean Institute of Gas
• /
• v.15 no.3
• /
• pp.74-78
• /
• 2011

$BF_3$ gas has been used for semiconductor manufacturing process and applied in plasma etching, chemical vapor deposition, chamber cleaning processes etc,. $BF_3$ provides Boron and acts as a p-type doping in electrode in semiconductor. In this study, we investigate thermaldecomposition of alkali-boron complexes and suggest a simple way to produce $BF_3$ from $NaBF_4$ and $KBF_4$.

• 연구논문집
• /
• s.30
• /
• pp.33-42
• /
• 2000

We must stabilize quickly increasing waste matters in urban life and livestock industry. Biogas including landfill gas and digester gas is byproduct of anaerobic decomposition of organic waste matter and contains 40%-70% methane, which can be used for energy purposes. Utilization of biogas reduce the emission of methane into the atmosphere to minimize greenhouse effect and the carbon dioxide (CO2) emitted when biogas is converted to energy has been taken out of the atmosphere by growing plant. Recently, bioenergy is world-widely noticeable as all contributing to the greenhouse effect. This paper presents development process of a biogas engine for cogeneration system and results of application to digester gas and landfill gas in site. The biogas engine is a dual fuel engine operated on biogas with a diesel pilot. At present, the engine can substitute biogas for diesel fuel up to 85%. but it can be said that there is a possibility of improvement in performance.

• The Bulletin of The Korean Astronomical Society
• /
• v.45 no.1
• /
• pp.61.1-61.1
• /
• 2020

We examine the HI gas kinematics and distribution of galaxy pairs in group or cluster environment from high-resolution Australian Square Kilometre Array Pathfinder (ASKAP) WALLABY pilot observations. We use 22 well-resolved galaxies in the Hydra cluster of which 4 galaxies are visually identified as pairs and others are isolated ones. We perform profile decomposition of HI velocity profiles of the galaxies using a new tool, BAYGAUD which enables us to separate a line-of-sight velocity profile into an optimal number of Gaussian components based on Bayesian MCMC techniques. All the HI velocity profiles of the galaxies are decomposed into kinematically cold or warm gas components with their velocity dispersion, 4~8 km/s or > 8 km/s, respectively. We derive the mass fraction of the kinematically cold gas with respect to the total HI gas mass, f = log10(M_cold / M_HI), of the galaxies and correlate them with their dynamical mass. The cold gas reservoir of the paired galaxies in the Hydra cluster is found to be relatively higher than that of the isolated ones which show a negative correlation with the dynamical mass in general.

• The Korean Journal of Ceramics
• /
• v.2 no.4
• /
• pp.231-237
• /
• 1996

Mullite ceramics can be sintered by rf plasma sintering to densities as high as 97% compared to the theoretical density of the mullite, while SiC whisker-reinforced mullite matrix ceramic composites were not sintered by plasma sintering. Decomposition of mullite occurs in a superficial regins at the outside surface of the specimen by volatilization of SiO at elevated temperature by plasma. SiC whiskers were destroyed, and the matrix was converted to alumina from SiC-whisker reinforced mullite matrix ceramic composites during the plasma sintering. Accelerated volatilization from the SiC whisker in the mullite prevents sintering. The volatile species are mainly SiC and CO gas species. The effects of plasma on mullite and SiC-whisker reinforced mullite matrix composites are interpreted by thermodynamic simulation of the volatile species in the plasma environment. The thermodynamic results show that the decomposition will not occur during hot pressing.