• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.193-201
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• 2000

Partitioning of hydrophobic organic compounds (HOCs) to a biosurfactant, hydroxypropyl-${\beta}$-cyclodextrin (HPCD), was conducted to evaluate the feasibility of using HPCD to remove HOCs from soil/groundwater. HOC partitioning to HPCD was very fast, with over 95% of the complexation occurring within 10 min. Some influence of solution chemistry and HOC concentration on HOC-HPCD complex formation coefficients was observed. HPCD sorption on soil as quantified by both a fluorescence technique and total organic carbon measurements was negligible, indicating no significant affinity of HPCD for the solid phase. Although the HOC solubilization capability of HPCD was lower than that of synthetic surfactants such as SDS and Tween 80, HPCD can be effective in removing sorbed HOCs from a model subsurface environment, primarily because of its negligible sorption to the solid phase (i.e., all the HPCD added facilitates HOC elution). However, in contrast with conventional surfactants, HPCD becomes relatively less effective for HOC partitioning with increasing HOC size and hydrophobicity. Therefore, comparisons between HPCD and synthetic surfactants for enhanced remediation applications must consider the specific HOC(s) present and the potential for surfactant material losses to the solid phase, as well as other more generally recognized considerations such as material costs and potential toxicological effects.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.11a
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• pp.52-52
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• 2011

PLA 섬유는 폴리머의 주성분이 옥수수에서 추출한 모노머를 중합한 화학섬유가 아닌 인체친화적인 식물성 소재이며 생분해성이 좋은 친환경 소재로 최근 주목받고 있는 섬유소재이다. 본 연구에서는 아토피완화용 여러 섬유 구조체 개발에서 사용되는 섬유소재중 PLA 원사에 항균성 물질을 혼입하여 PLA 항균사 제조를 위한 연구를 수행하였다. PLA Grade의 점도가 낮아질수록 Grade별 용융 지수값은 차이를 나타내지만 방사온도 $230^{\circ}C$를 변곡점으로 하여 용융점도가 급격히 변하였으며, 특히 방사온도 $240^{\circ}C$의 경우 용융지수가 100을 넘어가고 폴리머의 색깔이 황갈색을 띄어 폴리머의 열분해가 많이 일어났을 것으로 판단되었다. PLA의 적정 방사온도 구간은 $210{\sim}225^{\circ}C$ 구간이 최적이며 그 이상에서는 Color 변화 및 물성 저하가 나타나는 것으로 판단되었다. 항균성 PLA 섬유를 제조하기 위하여 피톤치드계 유기항균제를 이용하였으며, 피톤치드에 기능성 엘라스토머를 사용하여 Capsulation을 진행하였다. 이러한 유기항균제 Powder의 경우 비중이 낮아 표면적로 인하여 마스터배치 칩을 만드는 공정에서 잘 혼합되지 않는 문제점이 발생하였으나, 피톤치드의 함량을 조절하여 PLA와의 마스터배치 칩 제조를 시험하였다. 압출온도와 토출량, Screw 조건(Mixing, Zone)을 시험하여 적정 조건을 설정하였다. 항균사 PLA 섬유는 Sheath/Core 복합방사 형태와 단독사 형태의 2가지 Type을 제조하였다. Sheath/Core 복합방사 폴리머 구성은 Sheath부에 PLA항균사, Core부에 PLA 또는 저융점 PET를 사용하였다. Core부의 폴리머는 제사성에 큰 영향을 미치지 않았으나, 항균 마스터배치의 함량이 증가할수록 Pack압 상승이 급격히 일어나는 단점이 나타났다. 항균제 5% 정도가 혼입되어 있는 경우에 2.1 이상의 정균활성치와 99.8% 정도의 정균감소율 성능을 나타내었다. PLA 단독사의 경우, 항균제 최적 함량은 3% 이상으로 정균활성치 5.5 이상, 정균감소율 99.9%의 우수한 항균특성을 나타내었다.

• Clean Technology
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• v.5 no.1
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• pp.49-61
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• 1999

Fenton's oxidation can improve the biodegradability of refractory organic wastewater by generating $OH{\cdot}$ which is one of the most reactive species. Fenton's reagent is used to treat a variety of industrial waste containing a range of toxic organic compounds. But this process cannot be economical because of high chemical cost of $H_2O_2$, ferrous ion solution and high sludge disposal cost. In this study, we proposed a modified Fenton's oxidation process which can reduce the reagent cost and obtain better removal efficiencies with less Fenton's reagents, and have a good potential of sludge recycling. In modified Fenton reaction, ferrous ion solution is adjusted to optimal pH with NaOH. Then it added to the sample and reacted to $H_2O_2$. For the experiment, synthetic wastewater made of phenol, which is one of the typical water pollutants, was used and the ionic strength of this wastewater was controlled by adding $NaHCO_3$. The effects of DO, ionic strength, and $H_2O_2$ dosing methods were investigated. As a result, modified Fenton's treatment efficiencies are better than conventional Fenton's reaction treating leachate and dyeing wastewater. And modified Fenton's treatment efficiencies combined to the sludge recycling for a half of Iron dosage are as good as the conventional Fenton's for a normal Iron dosage.

• Journal of the Korean GEO-environmental Society
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• v.6 no.4
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• pp.27-35
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• 2005

A case study of the assessment for environmental stabilization in open dumping landfill site was carried out physical composition, total solid, moisture, and landfill gas(LFG) analysis in landfill site. The result of physical ratio were represented combustibles 23.64% and incombustibles 76.36%, TS 77.69%, VS 74.24%, FS 25.75%. The biodegradable organic matters were almost degraded and the result of the landfill gas showed that the $CH_4$ gas were measured as 4.5%. As the result of the assessment on the open dumping landfill it appears that this landfill is stabled for the maturation phase and formation $CO_2$ concentration lower than 15%.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.1
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• pp.49-54
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• 2012

Microbial changes in the characteristics of dissolved organic matter (DOM) and the subsequent effects on the conditional stability constants of copper were investigated using 14 day-incubations of Pony Lake fulvic acid (PLFA), Suwannee River fulvic acid (SRFA) and the mixtures of the humic substances and glucose. After incubation, dissolved organic carbon (DOC) concentrations were diminished, and specific UV absorbance values and DOC-normalized fluorescence intensities increased. The microbial changes were minimal for the samples contaning humic substances only whereas they were much pronounced for the mixtures with glucose. The extent of the changes increased with a higher content of glucose in the mixtures. The same trend was observed even for glucose solution. Our results suggest that labile organic moieties may be transformed into more chromophoric and humidified components by biodegradation. For the mixture samples, the copper binding stability constants did not change or even decreased after incubation. Therefore, microbially induced enrichment of the fulvic- and humic-like carbon structures in DOM appears to result in little change or the decrease of the copper binding coefficients.

• Journal of Korea Soil Environment Society
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• v.4 no.3
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• pp.17-24
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• 1999

The effects of hydrophobic chain length and its structure of nonionic surfactants on surfactant adsorption and contaminated diesel removal were studied in kaolin soil. Hydrocarbon chain length and double bond in hydrophobic tail group of nonionic surfactants affected surfactant adsorption and diesel removal efficiency from kaolin soil. The degrees of surfactant adsorption and diesel removal were closely related each other. Among nonionic surfactants we studied, surfactants with shorter hydrophobic chain length and higher HLB value showed lower degree of adsorption and higher efficiency of diesel removal. The existence of unsaturated carbons in the structure of hydrophobic chain enhanced diesel removal by reducing surfactant adsorption to kaolin soil. The best diesel removal was obtained after adsorption saturation was reached. If surfactant concentration was higher than a critical value, diesel removal was reduced probably because of precipitation. liquid crystal formation, or coacervation of surfactants at high concentration.

• Journal of the Korea Organic Resources Recycling Association
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• v.22 no.3
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• pp.41-52
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• 2014

In this study, to estimate the biodegradability of sewage discharged intermittently, field scale sampling and analysis was conducted and the results were obtained as follows. According to results of the biodegradability of sewage discharged intermittently, average concentration of TCODcr is 325.5mg/L and ratio of TCOD fraction resulted 100%. Also, average concentration of SCODcr resulted 135.9mg/L and ratio of TCOD fraction resulted 41.8%. Average concentration of Ss showed 74.1mg/L and ratio of TCOD fraction resulted 22.8%. Average concentration of $S_I$ was analyzed to be 61.8mg/L and ratio of TCOD fraction was calculated to 19.0%. Xs which is particulate matter was analyzed to show 27.8mg/L and ratio of TCOD fraction also showed 8.5%. Average concentration of $X_H$ is 103.4mg/L and ratio of TCOD fraction resulted 31.8%. Inert particulate matter showed that average concentration of $X_I$ is 58.5mg/L and ratio of TCOD fraction resulted 18.0%. Accordingly, dissolved biodegradable organic matter showed the ratio of 41.8%, and readily biodegradable matter among this showed 22.8%. Thus intermittent inflow is expected to have less effect with regards equalization by organic loading rate of influent.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.241-249
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• 2000

In this study, UV-catalyzed $H_2O_2$ oxidation and $H_2O_2$ oxidation to remove contaminants from photo processing chemicals were investigated at various conditions. Photo processing chemicals contains high concentrations of organic compounds and has very low biodegradability. Hydrogen peroxide is subjected to gradual decomposition as metastable substance. In the process, short-lived and highly reactive hydroxyl radicals are formed. The decomposition can be significantly accelerated by use of appropriate catalyst, such as ultraviolet radiation. The experiments were conducted in a UV-free reflecting reactor in batch and a high-pressure mercury lamp was used as UV source. Mixing, cooling and ventilation of the reactor were operated during experiments. In $UV/H_2O_2$ oxidation and $H_2O_2$ oxidation, the removal efficiencies of $COD_{Cr}$, TOC and chromaticity increased with the increase of $H_2O_2$ dosage and were higher in the controlled pH condition of 3 than in original pH condition of 8. In $UV/H_2O_2$ oxidation under the optimum condition of pH 8 and 1.3 stoichiometric $H_2O_2$ dosage, the removal efficiencies of $COD_{Cr}$, TOC and chromaticity were 47.5%, 75.0% and 91.5% respectively and $BOD/COD_{Cr}$ ratio was significantly increased from 0.04 to 0.21.

• Korean Journal of Ecology and Environment
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• v.45 no.2
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• pp.210-217
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• 2012

This study investigated the water quality of effluents from the wastewater treatment plants, located at the Gumi Complex 4, Gumi, and Wonpyong, in Gumi. DOC accounted for higher than 70% of TOC, and oxidation efficiencies, calculated from carbon, were 13~43% for BOD and 37~73% for CODMn, respectively. Based on the biological decomposition experiments, R-DOC account for higher than 70% of DOC, mostly being occupied by refractory organic matters. This indicated that the biodegradable organics occupied more proportions of organic loadings than the refractory organics. The effect of the organics from a discharge of a sewage treatment plant on rivers, Gumi industrial Complex 4, Gumi, and Wonpyong on lower streams of the Nakdong River were found to be 15%, 6% and 16% respectively. The ratio of 15% suggests that comparatively, no large portions of TOC loadings are occupied, but the problem is that the biodegradable organic matters occupy a lot more proportions than that of the refractory organic matters. Thus, it is highly estimated that the refractory organics can gradually increase the pollution level of organics and precursors of disinfection by-products to the down-stream water treatment plants.

• Journal of Soil and Groundwater Environment
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• v.11 no.6
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• pp.69-75
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• 2006

Improper disposal of petroleum and spills from underground storage tanks have created large areas with highly toxic contamination of the soil and groundwater. Methyl tert-butyl ether (MTBE) is widely used as a fuel additive because of its advantageous properties of increasing the octane value and reducing carbon monoxide and hydrocarbon exhausts. However, MTBE is categorized as a possible human carcinogen. This research investigated the Modified Photo-Fenton system which is based on the Modified Fenton reaction and UV light irradiation. The Modified Fenton reaction is effective for MTBE degradation near a neutral pH, using the ferric ion complex composed of a ferric ion and environmentally friendly organic chelating agents. This research was intended to treat high concentrations of MTBE; thus, 1,000 mg/L MTBE was chosen. The objectives of this research are to find the optimal reaction conditions and to elucidate the kinetic and mechanism of MTBE degradation by the Modified Photo-Fenton reaction. Based on the results of experiments, citrate was chosen among eight chelating agents as the candidate for the Modified Photo-Fenton reaction because it has a relatively higher final pH and MTBE removal efficiency than the others, and it has a relatively low toxicity and is rapidly biodegradable. MTBE degradation was found to follow pseudo-first-order kinetics. Under the optimum conditions, [$Fe^{3+}$] : [Citrate] = 1 mM: 4 mM, 3% $H_2O_2$, 17.4 kWh/L UV dose, and initial pH 6.0, the 1000 ppm MTBE was degraded by 86.75% within 6 hours and 99.99% within 16 hours. The final pH value was 6.02. The degradation mechanism of MTBE by the Modified Photo-Fenton Reaction included two diverse pathways and tert-butyl formate (TBF) was identified to be the major degradation intermediate. Attributed to the high solubility, stability, and reactivity of the ferric-citrate complexes in the near neutral condition, this Modified Photo-Fenton reaction is a promising treatment process for high concentrations of MTBE under or near a neutral pH.