• 동아시아식생활학회지
• /
• 제7권3호
• /
• pp.315-324
• /
• 1997

1.5, 3.0, 4.5, 6.0% active Cl/g starch를 포함하는 sodium hypochlorite 용액으로 pH 7.0에서 감자전분을 산화시켜 이화학적인 성질을 측정하였다. 산화 전분의 카르복실기 함량은 사용한 활성 염소농도에 비례하였고, 물결합력과 알칼리수, 용해도는 산화 정도가 높을수록 증가하였다. 청가와 요오드흡착특성에서는 산화에 의해 아밀로오스 구조가 변화되었음을 알 수 있었고, 광투과도와 DSC에 의한 호화양상에서는 산화 정도가 클수록 낮은 온도에서 호화되는 것으로 나타났다. X선 회절도와 주사전자 현미경으로 살펴 본 전분 입자의 형태로부터 산화는 주로 입자 표면의 무정형 부분에서 일어난 것으로 추정되었다.

• Korean Chemical Engineering Research
• /
• 제45권2호
• /
• pp.183-189
• /
• 2007

대표적인 수은 발생원인 도시폐기물 소각로와 화력 발전소 등지에서 배출되는 원소수은($Hg^0$)은 산화수은($Hg^{2+}$) 및 입자상 수은($Hg^p$)과 달리 기존의 대기오염 방지시설로 제거하기 난해한 편이다. 그로 인해 원소수은의 효율적 제거에 대한 많은 연구가 진행중이며, 이 연구에서는 저온 플라즈마(non-thermal plasma)의 하나인 유전체 장벽 방전(dielectric barrier discharge: DBD) 공정을 이용하여 원소수은 산화에 관한 실험을 수행하였다. 실험 결과, 공기 상의 DBD 공정에서는 생성되는 산소 원자와 오존에 의해서 원소수은이 산화수은으로 전환됨을 알 수 있었으며, 원소수은의 산화율을 결정하는 주된 변수는 반응기에 주입되는 에너지 밀도임을 확인할 수 있었다.

• 한국대기환경학회지
• /
• 제14권4호
• /
• pp.313-320
• /
• 1998

The most desirable diesel oxidation catalyst (DOC) should have the properties of oxidibing CO and HC effectively at low exhaust gas temperature while minimizing the formation of sulfate at high exhaust gas temperature. Precious metals such as platinum and palladium have been known to be sufficiently active for oxidizing CO and HC and also to have high activity for the oxidation of sulfur dioxide (SO2) to sulfor trioxide (SO3). There is a need to develop a highly selective catalyst which can promote the oxidation of CO and HC efficiently, but, on the other hand, suppress the oxidation of SO2. One approach to solve this problem is to load a base metal such as vanadium in Pt-based catalyst to suppress sulfate formation. In this study, a Pt-V catalyst was prepared by impregnating platinum and vanadium onto a Ti-Si wash coated catalyst in a laboratory reactor by changing the formulations and reaction temperatures.

• 한국환경과학회지
• /
• 제12권10호
• /
• pp.1071-1077
• /
• 2003

The aim of this study is, firstly, to find out what kinds of inorganic species are produced in the photocatalytic oxidation of ammonium-nitrogen containing water and, secondly, to seek the influence of anion for the photocatalytic oxidation of ammonium contained compounds. The photoenergy above 3 eV(λ <415 nm) was effectively absorbed by TiO$_2$ and TiO$_2$/polymer was used to be oxidized NH$_4$-N in wastewater to NO$_3$-N. Existing the anion as Cl$\^$-/, the rate of photocatalytic oxidation decreased regardless of other condition. This result showed that the chloride ions reduced the rate of oxidation by scavenging oxidizing radical species as OH$\^$-/ and OCl$\^$-/. Some of the added ion might have blocked the active sites of the catalyst surface, thus deactivated the catalyst.

• 한국표면공학회지
• /
• 제28권6호
• /
• pp.333-342
• /
• 1995

Stainless steels are widely selected as commercial engineering materials mainly because of their excellent corrosion resistance, oxidation resistance and strength. Because the manufacturing temperature of stainless steels is relatively high, the chemical and physical properties of the oxide film which was formed on the stainless steels are of importance in determining the rate of oxidation and the life of equipment exposed to high temperature oxidizing environments. In this study, the oxidation behavior of S. S. 304 and S. S. 430 added by a small amount of oxygen active elements(each +0.5wt% Hf and Y) was studied to improve oxidation resistance. The results of cyclic and isothermal oxidation on S. S. 304 added by OAE showed relatively poor oxidation resistance due to spallations and cracks of $Cr_2O_3$ layer. But all S. S. 430+0.5wt% OAE maintained constant oxidation rates and stable oxide layers at high temperature environment. Especially S. S. 430+0.5wt% Y formed a $Cr_2O_3$ oxide layer and improved cyclic oxidation resistance preventing loss of protective layers about 1000 hours at $1000^{\circ}C$

• 한국세라믹학회지
• /
• 제33권7호
• /
• pp.816-822
• /
• 1996

서로 다른 흑연화도를 갖는 furan 수지로 부터 얻어진 무기화합물(SiC, TiO2) 첨가 탄소재료의 산화반응의 흑연구조 의존성에 대하여 살펴보았다. 탄소재료의 산화는 시료의 표면적에 크게 의존하여, 흑연화가 상당히 진행된시료라 할지라도 표면적이 클 때는 살화속도도 빠른 것으로 밝혀졌으며, 단위 중량이 아닌 단위면적당의 산화속도로 바꿔 생각했을 때 흑연화가 진행될 수록 산화반응도 늦어지는 것을 알 수 있었다. 그리고 겉보기 활성화 에너지값으로 부터 생각할 때 흑연(TiO2 첨가시료)과 난층흑연(SiC 첨가시료)이 동일한 반응기구에 의해 산화가 진행되는 것으로 판단되었다. 또한 두종류 이상의 결정구조가 혼재하여 있는 시료의 경우 이들 성분들의 산화속도는 달라 반응의 초기에 흑연으로 결정화된 않은 비정질 탄소 성분이 흑연 성분보다 먼저 선택적으로 산화되는 것을 알 수 있었다.

• Korean Chemical Engineering Research
• /
• 제51권4호
• /
• pp.432-437
• /
• 2013

고분자 전해질 연료전지 구동 시 양극 활성 물질에 대한 CO 피독을 방지하기 위해 Cu를 촉매 활성 종으로 사용하고 반응물의 확산이 용이한 몇 가지 메조 세공 물질을 지지체로 이용하여 CO 선택적 산화 반응(PROX반응)을 실시하였다. 그 결과 거대 세공을 가진 SBA-15를 지지체로 사용했을 때 우수한 CO 산화 활성을 보였으며 특히 Cu 담지 량에 비례하여 활성은 증가하였다. 또한 Cu의 분산도를 높이고자 첨가한 Ti 성분은 저온에서 CO 산화 성능을 높이는데 기여하였다. 특히 Ti 성분을 20 wt-% 첨가한 Cu/Ti20-SBA-15 촉매에서 Cu의 분산도가 가장 우수하였으며 CO 산화활성 역시 개선됨을 확인하였다.

• 한국물환경학회지
• /
• 제38권5호
• /
• pp.211-219
• /
• 2022

In this study, the effect of liquid height/volume on sonochemical oxidation reactions was investigated in 300 kHz sonoreactors. The gas mixture of Ar/O₂ (50:50) was applied in two modes including saturation and sparging, and zero-order reaction (KI dosimetry) and first-order reaction (Bisphenol A (BPA) degradation) were used to quantitatively analyze sonochemical oxidation reactions. For the zero-order reaction, the highest sonochemical oxidation activity was obtained for the liquid height of 5𝛌, and the lowest height for both the gas saturation and sparging conditions. In addition, the sparging did not enhance the sonochemical oxidation activity for all height conditions except for 50𝛌, where very low activity was obtained. It was found that in sonochemiluminescence (SCL) images the sonochemical active zone was formed adjacent to the liquid surface for the gas sparging condition due to the formation of the standing wave field while the active zone was formed adjacent to the transducer at the bottom due to the blockage of ultrasound. For the first-order reaction, the highest activity was also obtained at 5𝛌 and the comparison based on the reactant mass was not appropriate because the concentration of the reactant (BPA) decreased significantly as the reaction time elapsed. Consequently, it was revealed that the determination of optimal liquid height (ultrasound irradiation distance) based on the wavelength of the applied ultrasound frequency was very important for the optimal design of sonoreactors in terms of reaction efficiency and reactor size.

• 상하수도학회지
• /
• 제37권5호
• /
• pp.253-259
• /
• 2023

Bioreactors are devices used by sewage treatment plants to process sewage and which produce active sludge, and sediments separated by solid-liquid are treated in anaerobic digestion tanks. In anaerobic digestion tanks, the volume of active sludge deposits is reduced and biogas is produced. After dehydrating the digestive sludge generated after anaerobic digestion, anaerobic digested wastewater, which features a high concentration of organic matters, is generated. In this study, the decomposition of organic carbon and nitrogen was studied by advanced oxidation process. Ozone-microbubble flotation process was used for oxidation pretreatment. During ozonation, the TOC decreased by 11.6%. After ozone treatment, the TOC decreased and the removal rate reached 80.4% as a result of the Ultra Violet-Advanced Oxidation Process (UV-AOP). The results with regard to organic substances before and after treatment differed depending on the organic carbon index, such as CODMn, CODCr, and TOC. Those indexes did not change significantly in ozone treatment, but decreased significantly after the UV-AOP process as the linkage treatment, and were removed by up to 39.1%, 15.2%, and 80.4%, respectively. It was confirmed that biodegradability was improved according to the ratio of CODMn to TOC. As for the nitrogen component, the ammonia nitrogen component showed a level of 3.2×10² mg/L or more, and the content was maintained at 80% even after treatment. Since most of the contaminants are removed from the treated water and its transparency is high, this water can be utilized as a resource that contains high concentrations of nitrogen.

• 동의신경정신과학회지
• /
• 제20권3호
• /
• pp.1-13
• /
• 2009

Objectives : The glial cell, located in between the blood vessel and nerve cell, takes charge of the cell support, nutrition supply, elimination of body waste, and cell action. GagamSohabhwangwon(GGSH), a chinese traditional medicinal prescription has been used orally for the treatment of seizures, infantile, convulsion, stroke and so forth. This paper examines the effect of the GagamSohabhwangwon(GGSH) essential oil on cell activity and anti oxidation. Methods : MTT assay methods were employed to measure the cell activity based on the amount of the GagamSohabhwangwon(GGSH) essential oil by using primarily cultivated glial cell. In addition, this paper measured a viability of the glial cell after a protein active retarder control to confirm the multiplication of the cell and examined the cell extinction by the active oxygen, an extinction shielding effect with different amount of the GagamSohabhwangwon(GGSH) essential oil to observe anti oxidation. Furthermore, this paper measured a viability of the cell and phosphorylation(phosphorylation) of the protein which affects the multiplication of the glial cell. Results : When controlling the amount of the GagamSohabhwangwon(GGSH), there was a multiplication effect of the primary glial cell, the multiplication of the cell was dependent on the density of the GagamSohabhwangwon. The multiplication power of the primary glial cell was suppressed by PKA inhibiter (H89). In compliance with the active oxygen the extinction of the primary glial cell was dependent on the density of the GagamSohabhwangwon, there was a shielding effect of the cell extinction when GagamSohabhwangwon(GGSH) was preprocessed. When inducing the multiplication of the primary glial cell, phosphorylation of the Akt, BDNF, CREB, ERK and ERM were increased. Conclusions: Based on the results, GagamSohabhwangwon essential oil will have the effect which activates the nervous system cell and protects the cell through anti oxidation.