• Environmental Engineering Research
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• 제8권2호
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• pp.72-81
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• 2003

• 한국응용과학기술학회지
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• 제25권1호
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• pp.32-40
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• 2008

1,4-Dioxane is an EPA priority pollutant often found in contaminated ground waters and industrial effluents. Conventional water treatment techniques are limited to decompose this compound effectively. Therefore, an advanced oxidation process system (AOP) was used for the degradation of 1,4-dioxane. This research investigates the effect of adding oxidants, such as ozone, air, and $H_2O_2$ during the UV irradiation of 1,4-dioxane solution. In order to analyze 1,4-dioxane, a modified 8270 method, which is an improved method of U.S EPA 8720, was used. Degradation efficiencies of 1,4-dioxane by only UV irradiation at various temperatures were not significant. However, The addition of oxidants and air bubbling in the UV irradiation system for 1,4-dioxane decomposition showed the higher 1,4-dioxane degradation rate. And, during AOP treatment the tendency of TOC changes was similar to that of 1,4-dioxane decomposition rate.

• 한국환경과학회지
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• 제15권1호
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• pp.67-75
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• 2006

The degradation of Rhodamine B (RhB) in water was investigated in laboratory-scale experiments, using five advanced oxidation Processes (AOPs) $UV/H_2O_2$, lenten, photo-lenten, $UV/TiO_2,\;UV/TiO_2/H_2O_2$. The photodegradation experiments were carried out in a fluidized bed photoreactor equipped with an immersed 32 W UV-C lamp as light source. initial decolorization rate and COD removal efficiency were evaluated and compared. The results obtained showed that the initial decolorization rate constant was quite different for each oxidation process. The relative order of decolorization was: photo-fenton > $UV/TiO_2/H_2O_2$ > fenton > $UV/H_2O_2$ > $UV/TiO_2$ > UV > $H_2O_2$. The relative order of COD removal was different from decolorization: photo-fenten ${\fallingdotseq}$ $UV/TiO_2/H_2O_2\;>\;UV/TiO_2\;>\;fenton\;>\;UV/H_2O_2$. The Photo-lenten and $UV/TiO_2/H_2O_2$ processes seem to be appropriate for decolorization and COD removal of dye wastewater.

• 대한환경공학회지
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• 제27권5호
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• pp.461-467
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• 2005

내분비계장애물질로 분류된 phthalate esters의 제거방법에 대해 연구하였다. 상수처리조건에서 회분식으로 제거실험을 한 결과 응집침전은 $26.6{\sim}33.8%$, 오존산화에서는 $10{\sim}15%$ 제거효율을 나타내었다. 상수처리조건에서 활성탄 흡착에 의해 효과적으로 제거되는 것으로 나타났고 연속공정에서 EBCT를 10분 운전했을 때 원수의 phthalate esters농도가 $100\;{\mu}g/L$일 경우 WHO 및 US EPA 먹는 물 기준 달성이 가능한 것으로 나타났다. Pilot plant 실험결과 응집침전공정에서 $32{\sim}44%$, 사여과 공정에서는 $6{\sim}10%$, 오존산화공정에서 $8{\sim}10%$의 제거효율을 보였으며 활성탄 흡착공정을 거친 후에는 4가지 물질(DEP, DBP, BBP 및 DEHP)모두 검출되지 않았다. 실제 고도처리 정수장에서의 공정별 phthalate esters 제거율은 응집침전 공정에서 $29{\sim}76%$ 정도 제거되었고 모래여과 공정에서 $3{\sim}29%$, 오존산화 공정에서 $17{\sim}22%$ 제거되었으며, 활성탄 처리 후에는 4가지 물질 모두 검출되지 않았다.

• 상하수도학회지
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• 제33권6호
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• pp.469-480
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• 2019

This study was conducted to evaluate the degradation and mineralization of PPCPs (Pharmaceuticals and Personal Care Products) using a CBD(Collimated Beam Device) of UV/H₂O₂ advanced oxidation process. The decomposition rate of each substance was regarded as the first reaction rate to the ultraviolet irradiation dose. The decomposition rate constants for PPCPs were determined by the concentration of hydrogen peroxide and ultraviolet irradiation intensity. If the decomposition rate constant is large, the PPCPs concentration decreases rapidly. According to the decomposition rate constant, chlortetracycline and sulfamethoxazole are expected to be sufficiently removed by UV irradiation only without the addition of hydrogen peroxide. In the case of carbamazepine, however, very high UV dose was required in the absence of hydrogen peroxide. Other PPCPs required an appropriate concentration of hydrogen peroxide and ultraviolet irradiation intensity. The UV dose required to remove 90% of each PPCPs using the degradation rate constant can be calculated according to the concentration of hydrogen peroxide in each sample. Using this reaction rate, the optimum UV dose and hydrogen peroxide concentration for achieving the target removal rate can be obtained by the target PPCPs and water properties. It can be a necessary data to establish design and operating conditions such as UV lamp type, quantity and hydrogen peroxide concentration depending on the residence time for the most economical operation.

• 한국분말재료학회지
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• 제26권4호
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• pp.290-298
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• 2019

$TiO_2$-particles containing Co grains are fabricated via thermal hydrogenation and selective oxidation of TiCo alloy. For comparison, $TiO_2$-Co composite powders are prepared by two kinds of methods which were the mechanical carbonization and oxidation process, and the conventional mixing process. The microstructural characteristics of the prepared composites are analyzed by X-ray diffraction, field-emission scattering electron microscopy, and transmission electron microscopy. In addition, the composite powders are sintered at $800^{\circ}C$ by spark plasma sintering. The flexural strength and fracture toughness of the sintered samples prepared by thermal hydrogenation and mechanical carbonization are found to be higher than those of the samples prepared by the conventional mixing process. Moreover, the microstructures of sintered samples prepared by thermal hydrogenation and mechanical carbonization processes are found to be similar. The difference in the mechanical properties of sintered samples prepared by thermal hydrogenation and mechanical carbonization processes is attributed to the different sizes of metallic Co particles in the samples.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.246-246
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• 2012

Smart catalyst design though novel catalyst preparation methods can improve catalytic activity of transition metals on reducible oxide supports such as titania by enhancement of metal oxide interface effects. In this work, we investigated Pt nanoparticles/titania catalysts under CO oxidation reaction by using novel preparation methods in order to enhance its catalytic activity by optimizing metal oxide interface. Arc plasma deposition (APD) and metal impregnation techniques are employed to achieve Pt metal deposition on titania supports which are prepared by multi-target sputtering and Sol-gel techniques. In order to tailor metal-support interface for catalytic CO oxidation reaction, Pt nanoparticles and thin films are deposited in varying surface coverages on sputtered titania films using APD. To assess the role of oxide support at the interface, APD-Pt is deposited on sputtered and Sol-gel prepared titania films. Lastly, characteristics of APD-Pt process are compared with Pt impregnation technique. Our results show that activity of Pt nanoparticles is improved when supported over Sol-Gel prepared titania than sputtered titania film. It is suggested that this enhanced activity can be partly ascribed to a very rough titania surface with the higher free metal surface area and higher number of sites at the interface between the metal and the support. Also, APD-Pt shows superior catalytic activity under CO oxidation as compared to Pt impregnation on sputtered titania support. XPS results show that bulk oxide is formed on Pt when deposited through impregnation and has higher proportion of oxidized Pt in the form of $Pt^{2+/4+}$ oxidation states than Pt metal. APD-Pt shows, however, mild oxidation with large proportion of active Pt metal. APD-Pt also shows trend of increasing CO oxidation activity with number of shots. The activity continues to increase with surface coverage beyond 100%, thus suggesting a very rough and porous Pt films with higher active surface metal sites due to an increased surface area available for the reactant CO and $O_2$ molecules. The results suggest a novel approach for systematic investigation into metal oxide interface by rational catalysts design which can be extended to other metal-support systems in the future.

• 한국표면공학회지
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• 제39권4호
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• pp.173-178
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• 2006

Incoloy alloy 909 is an Fe-Ni-Co based superalloy that is attractive for gas turbine engine applications. The absence of chromium, however, makes the alloy more susceptible to oxidation in high temperature. To improve the oxidation resistance aluminizing was performed by high activity low temperature pack cementation process. Aluminizing condition was examined with different times and temperatures. Optimum aluminizing conditions were at the temperature of $552^{\circ}C$ for 20 hrs. In the optimized condition, the thickness of the aluminized layer was about $20{\mu}m$. Also, the aluminized layer made the alloy to increase the resistance to the corrosion.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1993년도 추계학술발표회 초록집
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• pp.31-36
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• 1993

Three different methods were employed to measure the degree of aerial oxidation in coal and the resulting oxidation/weathering indices were applied to obtain kinetic parameters of aerial oxidation processes, The index (i.e., slurry pH, Free Swelling Index, weight gain) values were subjected to kinetic analysis based on power-law Arrhenius type reaction model. The results show that activation energy of the aerial oxidation in 20-29$0^{\circ}C$ is in the range of 12-16 ㎉/㏖ and the agreement among three techniques is remarkable. The first order kinetic model is suitable in describing low temperature aerial oxidation process, except in the FSI case where the zero order expression is the best one.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2005년도 국제학술대회
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• pp.351-354
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• 2005

The removal of 1,4-dioxane and the biodegradability enhancement of dioxane contaminated water was investigated using $O_3-H_2O_2$ based advanced oxidation process. Experiments were conducted using a bubble column reactor under different dioxane and peroxide concentrations as well as PH. The $O_3-H_2O_2$ process effectively converted dioxane to more biodegradable intermediates and increased the biodegradability and average oxidation state of dioxane in the solution.