• Asian Journal of Atmospheric Environment
• /
• v.5 no.3
• /
• pp.181-188
• /
• 2011

Photocatalysis is a photochemical catalytic reaction which is a highly promising tool for the environmental cleanup process. It is very effective in treatment of environmental pollutants by its unique redox property. It has wide applications in the treatment of atmospheric pollutants (e.g., nitrogen dioxide, trichloroethylene, volatile organics, hydrogen sulfide, benzene, etc) through oxidative removal and by disinfection (aeromicro flora). In this research, the fundamental aspects of photocatalysis are described with respect to the composition of catalysts, experimental conditions (e.g., temperature, duration, etc), and interfering factors (e.g., catalyst deactivation).

• Journal of Life Science
• /
• v.8 no.5
• /
• pp.550-556
• /
• 1998

In order'to reduce loss of shrimp productivity by viral diseases on the cultured shrimp, we were develope the effective shrimp virus control system. Virus is inactivated by above 5 ppm of chloride and treatment of 50% fresh water. Mortality of infected shrimp is decreased by feeding of immunostimulants such as peptidoglycan and schizophyllan. Mg(OH)$_2$ was one of improvement agents which have best effect on pH, ignition loss(IL), chemical oxidation demand(COD) and total sulfide of water and sediment of shrimp farm.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2004.09a
• /
• pp.394-398
• /
• 2004

This study was carried out to plan the prevention of the generation and discharge of acid mine drainage (AMD). Hydraulic characteristics were tested with the disk tension infiltrometer around the waste rock dump of the Imgi abandoned pyrophyllite mine in Busan, Korea. Because the waste rock dump of the Imgi mine have very low infiltration rate, most of rain was expected flowing into adjoined stream through the slope or plane as surface flow rather then throughflow or ground water. But slopes of the waste rock dump have many 'V' type erosion gullies and consist multi-layers. These gullies and multi-layers have coarse clastic particle layer which have very large hydraulic conductivity. So through these coarse clastic particle layers a large part of rain flow into ground. And also these layers could be played a function of aeration path, which induced oxidation of sulfide minerals and generation of AMD continuously.tinuously.

• Journal of the Korean institute of surface engineering
• /
• v.43 no.1
• /
• pp.31-35
• /
• 2010

Coatings of Ni-17 at.%W were electroplated on a steel substrate, and their corrosion behavior was investigated between 600 and $800^{\circ}C$ in an Ar-0.2%$SO_2$ atmosphere. They delayed the corrosion of the steel substrate. They were corroded into an outer NiO-rich layer, and an inner ($WO_3+NiO+NiWO_4$)-mixed oxide layer. Below these oxide layers, a sulfide layer gradually formed.

• Bulletin of the Korean Chemical Society
• /
• v.19 no.12
• /
• pp.1355-1359
• /
• 1998

The treatment of 1,1-bis(phenylthio)-2,2,3,3,3-pentafluoropropylbenzene (1) with 2 equiv. of phenyllithium in THF at -78 ℃ resulted in the formation of isomeric mixture (70: 30) of trifluoromethylated 1,2-diphenylvinyl sulfide 2 in 87% yield. The further oxidation of 2 with m-chloroperbenzoic acid in methylene chloride afforded isomeric mixture (70:30) of trifluoromethylated 1,2-diphenylvinyl sulfone 3 in 87% yield. When 3 was reacted with carbon nucleophiles such as methyllithium, n-butyllithium, phenyllithium and lithium octylide, the corresponding addition-elimination adducts 4, 5, 6 and 7 were obtained in moderate to good yields. The reaction of 3 with 4 equiv. of tributyltin hydride in benzene at reflux temperature provided isomeric mixture (90 : 10) of trifluoromethylated 1,2-diphenylvinyl stannane 8 in 41% yield. The reaction of 8 with methyllithium in the presence of trimethylsilyl chloride gave isomeric mixtures (90: 10) of trifluoromethylated 1,2-diphenylvinyl silane 9 in 88% yield. Finally, the treatment of 8 with Br2 and 12 resulted in the formation of isomeric mixtures (90: 10) of trifluoromethylated 1,2-diphenylvinyl bromide 10 and iodide 11 in 72% and 90% yields, respectively.

• Journal of Korean Society of Water and Wastewater
• /
• v.25 no.6
• /
• pp.815-824
• /
• 2011

In this study, a non-thermal plasma system was employed to simultaneously remove odorous compounds and organic sludge. The system consisted of two reactors; the first one was the non-thermal plasma reactor where ozone was produced by the plasma reaction and the ozone oxidized hydrogen sulfide, the model odorous compound, and then the ozone-laden gas stream was introduced to the second reactor where wasted sludge was disintegrated and solubilized by ozone oxidation. In this study, the gas retention time (GRT) and the hydraulic retention time (HRT) were changed in the two-reactor system, and the effects of GRT and HRT on reduction efficiencies of odor and sludge were determined. As the GRT increased, the ozone concentration increased resulting in an increasing efficiency of hydrogen sulfide removal. However, the overall ozone loading rate to the second sludge reactor was the same at any GRT, which resulted in an insignificant change in sludge reduction rate. When HRTs in the sludge reactor were 1, 2, 4 hours, the sludge reduction rates were approximately 30% during the four-hour operation, while the rate increased to 70% at the HRT of 6 hours. Nevertheless, at HRTs greater than 4 hours, the solubilization efficiency was not proportionally increased with increasing specific input energy, indicating that an appropriate sludge retention time needs to be applied to achieve effective solubilization efficiencies at a minimal power consumption for the non-thermal plasma reaction.

• Microbiology and Biotechnology Letters
• /
• v.32 no.4
• /
• pp.328-333
• /
• 2004

To treat a waste gas containing a high strength H2S, the two-stages microbial desulfurization process that conof a bioreactor immobilized with Acidithiobacillusferrooxidans and a chemical absorption scrubber has was proposed. After 4 times repeat of batch cultures, the immobilized bioreactor has been stabilized and the rate of iron oxidation reached 0.89 kg . $m^{-3}{\cdot}m^{-1}$ at steady state. The two-stages microbial desulfurization prowas able to be operated for a long term over 54 days. The removal efficiencies of H2S were 97-99% at a space velocity of 70 h-I and a inlet concentration of 37,000 ppmv. The maximum elimination capacity of H2S was approximately 3.3 kg S . $m^{-3}{\cdot}m^{-1}$. In the bioractor, the concentrations of the $Fe^{3+}$ and the immobilzed cell were constantly maintained during the desulfurization.

• Journal of Soil and Groundwater Environment
• /
• v.19 no.1
• /
• pp.54-62
• /
• 2014

To better understand dissimilatory iron and sulfate reduction (DIR and DSR) by subsurface microorganisms, we investigated the effects of sulfate and electron donors on the microbial goethite (${\alpha}$-FeOOH) reduction. Batch systems were created 1) with acetate or glucose (donor), 2) with goethite and sulfate (acceptor), and 3) with aquifer sediment (microbial source). With 0.2 mM sulfate, goethite reduction coupled with acetate oxidation was limited. However, with 10 mM sulfate, 8 mM goethite reduction occurred with complete sulfate reduction and x-ray absorption fine-structure analysis indicated the formation of iron sulfide. This suggests that goethite reduction was due to the sulfide species produced by DSR bacteria rather than direct microbial reaction by DIR bacteria. Both acetate and glucose promoted goethite reduction. The rate of goethite reduction was faster with glucose, while the extent of goethite reduction was higher with acetate. Sulfate reduction (10 mM) occurred only with acetate. The results suggest that glucose-fermenting bacteria rapidly stimulated goethite reduction, but acetate-oxidizing DSR bacteria reduced goethite indirectly by producing sulfides. This study suggests that the availability of specific electron donor and sulfate significantly influence microbial community activities as well as goethite transformation, which should be considered for the bioremediation of contaminated environments.

• Journal of Korean Society of Water and Wastewater
• /
• v.24 no.1
• /
• pp.85-92
• /
• 2010

In this study, odorous compounds emitted from various wastewater treatment were treated with using the non-thermal plasma reaction, and the effluent gas from the plasma reactor was introduced to a waste sludge reactor to achieve simultaneous sludge reduction. Hydrogen sulfide, the model odorous compound, was removed at 70% using the plasma reaction, and greater than 99% removal efficiency was observed when treated by the sludge reactor. In addition, the sludge reactor showed a high efficiency of ozone removal. As ozone reacted with sludge, oxidation with organic matters took place, and total COD decreased by 50~60% and soluble COD increased gradually. As a result, the integrated process consisting of the non-thermal plasma and the sludge reactor can be successfully applied for the simultaneous treatment of malodorous gas and waste sludge.

• Korean Journal of Metals and Materials
• /
• v.48 no.4
• /
• pp.277-288
• /
• 2010

The hot corrosion properties of heat-resistant steels were investigated in an oxidation atmosphere including artificial ash and sulfur dioxide. The heat-resistant steels of T22, T92, T122, T347HFG, Super304H and HR3C were evaluated at 620, 670 and $720^{\circ}C$ for 400 hours. The relationship between the corrosion rate and the temperature followed a bell-shaped curve with a peak rate at around $670^{\circ}C$. The corrosion rates showed a decreasing tendency as the chrome contents of these steels increased from 2.15 wt.% to 24.5 wt.%, and austenitic steels had a lower corrosion rate than ferritic steels. Sulfidation by $SO_2$ as well as molten salt corrosion also had an effect on the total corrosion rate, especially showing an increase in the corrosion rate in ferritic steels. Regardless of the chrome content in the steels and irrespective of the test temperature, the corrosion scale was composed of an outer oxide and an artificial ash mixed layer, a middle oxide layer and inner sulfide, and a mixed oxide layer. As the chrome content increased, the proportion of chrome oxide in the corrosion scale increased. Before spalling of the corrosion scale, voids and cracks were initiated in the sulfide and the mixed oxide layer or at the interface with the substrate.