• Journal of Environmental Science International
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• v.22 no.9
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• pp.1089-1095
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• 2013

The degradation of 3-chlorophenol(3-CP) by various AOPs(Advanced Oxidation Processes) including the ultraviolet / hydrogen peroxide, the Fenton and the ultraviolet(UV)-Fenton process has been conducted. The highest removal efficiency for 3-CP in the aqueous phase was obtained by the UV-Fenton process among the AOPs. In the UV-Fenton process, The removal efficiency of 3-CP decreased with increasing pH in the range of 3 to 6, and it decreased with increasing initial concentration. As the intermediates of 3-CP by UV-Fenton reaction, 3-chlorocatechol, 4-chlorocatechol, and chlorohydroquinone were detected thus the degradation pathways were proposed.

• Journal of Food Hygiene and Safety
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• v.9 no.4
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• pp.185-189
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• 1994

This study was to investigate time-dependent degradation process under various pH condition for organophosphorus(org-p) insecticides, namely Demeton-s-methyl, diazinon, Parathion, Phenthoate, and EPN in several waters. They were analysed by GC-FTD according to standard methods for the examination of water and wastewater. In pH=4, diazinon showed disappearance after 14 days in chromatogram. In pH=11, org-p insecticides were almost degradable after 7 days. In this condition, effect of pH on degradation process was greater than of light. In pH=7, org-p insecticides persisted residues after 112 days except Demeton-s-methyl. In BOD5 120, 250 ppm and domestic water, org-p insecticides showed also rapid degradation process.

• Journal of Power System Engineering
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• v.18 no.6
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• pp.84-90
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• 2014

The degradation of 2,3-dichlorophenol(2,3-diCP) by various advanced oxidation systems with continuous feeding of hydrogen peroxide including the ultraviolet/hydrogen peroxide, the Fenton and the photo-Fenton process has been conducted. The highest removal efficiency for 2,3-diCP in the aqueous phase was obtained by the photo-Fenton process among the advanced oxidation systems. In the photo-Fenton process, The removal efficiency of 2,3-diCP decreased with increasing pH in the range of 3 to 6, and it decreased with increasing initial concentration. As the intermediates of 2,3-diCP by photo-fenton reaction, 3,4-chlorocatechol and 2,3-dichlorohydroquinone were detected, thus the degradation pathways were proposed.

• Environmental Engineering Research
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• v.25 no.3
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• pp.316-323
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• 2020

The degradation of aqueous oxytetracycline (OTC) from an aqueous solution antibiotic using H₂O₂/Fe²⁺ process was studied in one 1 L batch chemical reactor. The extent of OTC degradation (20 mg/L) was investigated from a known initial pH solution, temperature and the type of catalyst (Fe²⁺, Fe³⁺) and for various initial concentrations of OTC, H₂O₂ and Fe²⁺. The degradation efficiency achieved was found to be very important (90.82% and 90.63%) at initial pH solution of 3 and 4, respectively. However, the type of catalyst and the reaction temperature had a slight impact on the final degradation of OTC. The results showed that the OTC removal increased with increasing initial H₂O₂ concentration in the range of 70 to 150 mg/L and initial Fe²⁺ concentrations in the range of 2 to 5 mg/L. The highest degradation efficiency obtained at ambient temperature was 90.95% with initial concentration of OTC of 10 mg/L, H₂O₂ = 150 mg/L and Fe²⁺ = 5 mg/L. Moreover, biodegradability improved from 0.04 to 0.36 and chemical oxygen demand degradation was 78.35% after 60 min of treatment. This study proved that Fenton process can be used for pretreatment of wastewater contaminated by OTC before a biological treatment.

• Journal of Hydrogen and New Energy
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• v.27 no.3
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• pp.290-297
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• 2016

The absorbent loss due to degradation in $CO_2$ capture process using aqueous alkanol amine solution has adverse effect on the economics of overall process. The degradation causes absorbent loss, equipment corrosion, foaming, adhesive material producing and viscosity increase in operation. In this study, the degradation characteristics of $CO_2$ capture process using MEA (monoehtanolamine) under various conditions such as $O_2$ partial pressure, $CO_2$ loading and absorbent temperature. The effects of iron, which generated from the equipment corrosion, on absorbent degradation were studied using $Fe_2SO_4$ containing MEA solution. The produced gases were analyzed by FT-IR(Fourier Transform Infrared Spectrophotometer) and the specifically measured $NH_3$ concentration was used as a degradation degree of aqueous MEA solution. The experiments showed that the higher $CO_2$ loadings (${\alpha}$), $O_2$ fraction ($y_{O2}$) and reaction temperature enhanced the more degradation of aqueous MEA solution. Comparing other operation parameters, the reaction temperature most affected on the degradation. Therefore, it could be concluded that the above parameters affects on degradation should be considered for the selections of $CO_2$ absorbent and operating conditions.

• Journal of Environmental Science International
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• v.21 no.4
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• pp.411-419
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• 2012

In this study, Ibuprofen (IBP) degradation by the photo catalytic process was investigated under various parameters, such as UV intensity, optimum dosage of $TiO_2$, alkalinity, temperature and pH of bulk solution. The pseudo-first order degradation rate constants were in the order of $10^{-1}$ to $10^{-4}min^{-1}$ depending on each condition. The Photocatalytic IBP degradation rate increased with an increase in the applied UV power. At high UV intensity a high rate of tri-iodide ($I_3{^-}$) ion formation was also observed. Moreover, in order to avoid the use of an excess catalyst, the optimum dosage of catalyst under the various UV intensities (30 and 40 W/L) was examined and ranged from approximately 0.1 $gL^{-1}$. The photo catalytic IBP degradation rate was changed depending on the alkalinity and temperature and pH in the aqueous solution. This study demonstrated the potential of photo catalytic IBP degradation under different conditions.

• Journal of Korean Society on Water Environment
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• v.21 no.4
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• pp.347-352
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• 2005

The isolated microorganisms, Pseudomonas stutzeri, Raoultella planticola (Klebsiella), Serratia fonticola from petroleum contaminated soil were enriched on benzene, toluene, ethylbenzene, o-xylene as carbon and energy sources, respectively. And the degradation characteristics of BTEX was observed in the mixed BTEX substrates. We found that the BTEX in mixed substrates were degraded more than 50% by three isolated microorganisms. Among three isolated microorganisms, the highest degradation rate was observed in Pseudomonas stutzeri, but the degradation rate was different according to microorganisms. In order to increase the degradation efficiency, we applied the co-culture of isolated three microorganisms. The mixture rate of pseudomonas stutzeri : Raoultella planticola (Klebsiella) : Serratia fonticola was follows ; 1:2:1, 1:1:2, and 2:1:1, respectively. In two co-culture of 1:2:1 and 1:1:2, degradation rate was lower than isolated microorganisms. However, degradation rate became higher than isolated microorganisms and the degradation rate of benzene, toluene, and ethylene was more than 95% in co-culture of 2:1:1. The degradation rate increased through the co-culture of isolated microorganisms, however, the growth rate decreased. This was resulted from the substrate competition between microorganisms. The co-culture of microorganisms is a effective method to increase the degradation efficiency of BTEX and the co-culture mixing rate is a important factor for determination of degradation efficiency.

• Bulletin of the Korean Chemical Society
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• v.21 no.1
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• pp.69-74
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• 2000

Applicability of Thermal field flow fractionation (ThFFF) was investigated for the analysis of masticated natural rubber (NR) adhesives produced bya hot melt mastication process. An optimum ThFFF condition for NR analysis was found by using tetrahydrofuran (THF) as a solvent/carrier and a field-programming. Low flowrate (0.3 mL/min) was used to avoid stopping the flow for the sample relaxation. Measured molecular weight distribution was used to monitor degradation of rubber during the mastication process. Rubber samples collected at three different stages of the mastication process and were analyzed by ThFFF. It was found that in an anaerobic process rubber degradation occurs at the resin-mixing (compounding) zone as well as in the initial break-down zone, while in an aerobic process most of degradation occurs at the initial breakdown zone. It was also found that E-beam radiation on NR causes a slight increase in the NR molecular weight due to the formation of a branched structure.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.519-522
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• 2002

In this paper, we analyze the impact of plasma etching process induced device degradation on low temperature poly-Si TFTs. The results indicate the relationship between device degradation and PPID effect during plasma fabrication. The dual-gate structure, which is used to suppress leakage current, is also discussed in this research.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04b
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• pp.49-52
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• 2002

Degradation characteristics of cathodoluminescence (CL) of ZnS:Ag,Cl phosphor were investigated with measurements of CL and photoluminescence (PL). Phosphoric acid treatment was performed to phosphor particles in order to improve CL degradation of phosphor screen that occurred during panel sealing process, and we will discuss mechanisms of degradation and improvement of luminescence mainly with help of AES (auger electron spectroscopy) analysis.