• Journal of Korean Society of Environmental Engineers
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• v.32 no.11
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• pp.1063-1068
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• 2010

This study compared UV and UV/$H_2O_2$ inactivation of E.coli, a possible indicator microorganism for fecal contamination of water, and $Q{\ss}$ phage, an indicator for pathogenic viruses. UV inactivation of $Q{\ss}$, T4 and lambda phages in actual secondary effluent was investigated, too. As a result, similar inactivation efficiency between $Q{\ss}$ phage and E.coli was observed during UV treatment, while $Q{\ss}$ phage showed higher resistance to UV/$H_2O_2$ than E.coli. $Q{\ss}$ phage resistance to UV or UV/$H_2O_2$ does not reflect those of all pathogenic viruses. However, the result tells that the use of E.coli inactivation efficiency in evaluating microbiological safety of water could not always ensure the sufficient safety from pathogenic viruses. Meanwhile, $Q{\ss}$ phage showed less resistance to UV than T4 and lambda phages, indicating that the use of $Q{\ss}$ phage as an indicator virus may bring insufficient disinfection effectiveness by causing the introduction of lower UV dose than required. Consequently, it can be thought that T4 or lambda phages would be more desirable indicators in ensuring the sufficient disinfection effectiveness for various pathogenic viruses.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1657-1661
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• 2011

In this study, CdSe-$TiO_2$ photocatalyst were synthesized by a facile solvothermal method and characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and UV-vis diffuse reflectance spectrophotometer. The photocatalytic activity was investigated by degrading methylene blue (MB) in aqueous solution under irradiation of UV light as well as visible light. The absorbance of degraded MB solution was determined by UV-vis spectrophotometer. The results revealed that the CdSe-$TiO_2$ photocatalyst exhibited much higher photocatalytic activity than $TiO_2$ both under irradiation of UV light as well as visible light.

• Proceedings of the SCSK Conference
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• 1992.09a
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• pp.97-114
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• 1992

In these days sun products are developed and produced by the cosmetic scientists in the world. Peoples need strongly to protect themselves from the hazardous UV rays dued to the destruction of ozone layer. Therfore, we, cosmetic scientists must have an effort to produce the more effective goods. In this article the market survey of sun-products as well as the currency of sunscreen agents was investigated. It was found that Benzophenone - 3 and Ocytyl methoxy cinnamate were widely used. The lotions, using Benzophenone - 3 as the chemical agents, and TiO$_2$and micro TiO$_2$ as the physical agents, were measured the UV-Spectrum in the Dilution and Application method. Photoprotective activity of chemical agents can usually be measured in solution state. However, that of the insoluble physical agents such as TiO$_2$is hardly measured in this state. Photoprotective ability of the insoluble physical agents was able to be measured by application of lotions to the surface of UV cells. It was found by this method that micro TiO$_2$showd stronger UV scattering effect than TiO$_2$in this method.

• Journal of the Korean GEO-environmental Society
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• v.23 no.10
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• pp.5-12
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• 2022

In this study, we investigated the UV/H₂O₂ process to treat organic compound-spilled water. In consideration of usage and properties, benzene, toluene, phenol, and methyl ethyl ketone were selected as representative organic compounds. The selected material was first removed by natural volatilization and aeration that simulated the pretreatment of the prcoess. After that, UV/H₂O₂ oxidation experiments were conducted under various H₂O₂ concentration conditions. Benzene and toluene were mostly volatilized before reaching the oxidation process due to high volatility. Considering the volatility, oxidation experiments were performed at an initial concentration of 5 mg/L for benzene and toluene. The UV/H₂O₂ oxidation process achieved 100% of benzene and toluene removal after 20 minutes under all hydrogen peroxide concentration conditions. The phenol was rarely removed from the volatile experiments and oxidation tests were performed at an initial concentration of 50 mg/L. The process showed 100 % phenol removal after 30 minutes under 0.12 v/v% of hydrogen peroxide concentration condition. Methyl ethyl ketone was removed 58 % after 2 hours of volatile experiments. The process showed 99.7% Methyl ethyl ketone removal after 40 minutes under 0.08 v/v% of hydrogen peroxide concentration condition. It was confirmed that the UV/H₂O₂ process showed high decomposition efficiency for the four selected organic compounds, and identified the amount of hydrogen peroxide in classified organic contaminants.

• Journal of Industrial Technology
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• v.31 no.B
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• pp.119-125
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• 2011

N-doped Titanium oxides were prepared by using urea as a source of nitrogen. The photoactivities of the doped $TiO_2$ were evaluated on the basis of degradation of humic acid in aqueous solutions with different light sources, ultraviolet lamp, fluorescent lamp and solar light. XRD analysis was conducted to identify the crystal structure of the synthesized photocatalysts. N-doped $TiO_2$ and $pure-TiO_2$ was anatase type. SEM results showed that spherical particles were formed, which are the characteristics of the anatase form. N doped $TiO_2$ showed higher $UV_{254}$ decrease ratio and DOC removal ratio compared to $pure-TiO_2$. The humic acid degradation reaction using the UV-A lamp and UV-C lamp was assigned to pseudo-first order reaction. For solar light, only $pure-TiO_2$ and $N-TiO_2$ exhibited the pseudo-first order reaction.

• Korean Journal of Microbiology
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• v.37 no.2
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• pp.130-136
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• 2001

The killing effects of two types(one-phase reactor and two-phase reactor) of UV-TiO$_2$photocatalytic system on the microorganisms have been studied. The UV-lamp which emits maximum 39 watts at 254 nm was prepared in these system. Three types of $TiO_2$ coating method were adopted. One type is thin film coated form on the quartz tube in the reactor and another one is surface rough coated form on the glass bead. The other one is $TiO_2$-mixed alginate bead form. UV irradiation was carried out for 1 min. In case of one phase reactor, the bactericidal efficiencies of E. coli by $TiO_2$-coated quartz tube and $TiO_2$-coated glass bead were 63.2% and 89.9%, respectively. In the air-bubbling system, the bactericidal efficiency was 95%, however, the efficiency decreased to 90.6% in the non-bubbling system. In the $TiO_2$-mixed alginate bead system, bactericidal efficiency was 86%. When $H_2O$$_2$ was treated (10, 15, 20, and 25 mg/ι) to the $TiO_2$-coated glass bead reactor, bactericidal efficiency significantly increased according to the concentration of $H_2$$O_2$. Two phase reactor showed more elevated efficiency. E. coli was more sensitive to the reaction than S. cerevisiae.

• Journal of the Mineralogical Society of Korea
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• v.27 no.4
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• pp.223-233
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• 2014

Cyanidation method has been used to extract high-purity gold and silver in mining industry. Such mining activities have used a large amount of cyanide, and the mine wastewater contained a high level of cyanide has brought about pollution of surrounding aqueous environments. This research was initiated to study $TiO_2$-catalytic UV-LED photo-oxidation to remove cyanide from the mine wastewater. UV lamp has been generally used as a light source in conventional photo-oxidation so far, but it shows numerous drawbacks. For this reason, this study focused on the evaluation of applicability of UV-LED as an alternative light source in cyanide photo-oxidation process. Three types of $TiO_2$ photo-catalyst were compared in terms of performance of photo-oxidation of cyanide, and the results show that Degussa P25 was the most efficient. In addition, four types of UV-LED were tested to compare their efficiencies of cyanide photo-oxidation, and their efficacy was increased in the order of 365 nm lamp-type > 365 nm can-type > 280 nm can-type > 420 nm lamp-type. Not only did this study demonstrate that UV-LED can be used in the photo-oxidation of cyanide as an alternative light source of UV lamp, but also confirmed that the performance of photo-oxidation was significantly influenced by the type of $TiO_2$ catalysts.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.1
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• pp.69-75
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• 2009

The characteristics of disinfection and organic removal were investigated with pulse UV lamp in this study. The intensity and emission wavelength of pulse UV Lamp were compared with low pressure UV lamp. The emission spectrum range of pulse UV lamp was between 200 and 400 nm while the emission spectrum of low pressure UV lamp was only single wavelength of 254nm. 3 Log inactivation rate of B. subtilis spore by pulse UV and low pressure UV irradiation was determined as $44.71mJ/cm^2$ and $57.7mJ/cm^2$, respectively. This results implied that wide range of emission spectrum is more effective compared to single wavelength emission at 254nm. 500ng/L of initial 2-MIB concentration was investigated on the removal efficiency by UV only and $UV/H_2O_2$ process. The removal efficiency of UV only process achieved approximately 80% at $8,600mJ/cm^2$ dose. 2-MIB removal rate of $UV/H_2O_2$ (5 mg/L $H_2O_2$) process was 25 times increased compared to UV only process. DOC removal efficiency for the water treatment plant effluent was examined. The removal efficiency of DOC by UV and $UV/H_2O_2$ was no more than 20%. Removal efficiency of THMFP(Trihalomethane Formation Potential), one of the chlorination disinfection by-products, is determined on the UV irradiation and $UV/H_2O_2$ process. Maximum removal efficiency of THMFP was approximately 23%. This result indicates that more stable chemical structures of NOM(Natural Organic Matter) than low molecule compounds such as 2-MIB, hydrogen peroxide and other pollutants affect low removal efficiency for UV photolysis. Consequently, pulse UV lamp is more efficient compared to low pressure lamp in terms of disinfection due to it's broad wavelength emission of UV. Additional effect of pulse UV is to take place the reactions of both direct photolysis to remove micro organics and disinfection simultaneously. It is also expected that hydrogen peroxide enable to enhance the oxidation efficiency on the pulse UV irradiation due to formation of OH radical.

• Journal of Environmental Science International
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• v.31 no.8
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• pp.677-689
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• 2022

In order to photocatalytically treat organic matter (COD_Cr) and chromaticity effectively, chemical coagulation and sedimentation processes were employed as a pretreatment of the leachate produced from landfill in Jeju Island. This was performed using FeCl₃·6H₂O as a coagulant. For the treated leachate, UV/TiO₂ and UV/TiO₂/H₂O₂ systems were investigated, using 4 types of UV lamps, including an ozone lamp (24 W), TiO₂ as a photocatalyst, and/or H₂O₂ as an initiator or inhibitor for photocatalytic degradation. In the chemical coagulation and sedimentation process using FeCl₃·6H₂O, optimum removal was achieved with an initial pH of 6, and a coagulant dosage of 2.0 g/L, culminating in the removal of 40% COD_Cr and 81% chromaticity. For the UV/TiO₂ system utilizing an ozone lamp and 3 g/L of TiO₂, the optimum condition was obtained at pH 5. However, the treated COD_Cr and chromaticity did not meet the emission standards (COD_Cr: 400 mg/L, chromaticity: 200 degrees) in a clean area. However, for a UV/TiO₂/H₂O₂ system using 1.54 g/L of H₂O₂ in addition to the above optimum UV/TiO₂ system, the results were 395 mg/L and 160 degrees, respectively, which were within the emission standard limits. The effect of the UV lamp on the removal of COD_Cr, and chromaticity of the leachate decreased in the order of ozone (24 W) lamp > 254 nm (24 W) lamp > ozone (14 W) lamp > 254 nm (14 W) lamp. Only COD_Cr and chromaticity treated with the ozone (24 W) lamp met the emission standards.

• Journal of Life Science
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• v.9 no.5
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• pp.581-589
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• 1999

This study was carried out to compare ozonation with photocatalysis degradation for removal Geosmin of algae byproduct. The change of pH was decresed from 7.02 to 2.8 after contact time 480 minute for ozonation. In case of UV-germicidal lamp, pH was very quickly increased from 7.02 to 7.5, but Halogen lamp did very slowly change pH. Geosmin degradation ratio was as following, UV-germicidal lamp/TiO2(100mg/L) O3>UV-germicidal lamp/TiO2(50mg/L)>UV-germicidal lamp(10W)>halogen lamp(50W). Instead of TiO2 suspension solution, Geosmin degradation ratio was very low using hollow bead and pellet as coated TiO2. As a result of identifing byproducts, ozonation generated three species of aldehyde such as 3-Heptanone and three species of alcohol such as Heptanal, but photocatalysis formed 1, 14-Tetradecanediol infinitesimally.