• Molecules and Cells
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• 제21권1호
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• pp.161-165
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• 2006

Dichlorodihydrofluorescein ($DCFH_2$) is a widely used probe for intracellular $H_2O_2$. However, $H_2O_2$ can oxidize $DCFH_2$ only in the presence of a catalyst, whose identity in cells has not been clearly defined. We compared the peroxidase activity of Cu,Zn-superoxide dismutase (CuZnSOD), cytochrome c, horseradish peroxidase (HRP), $Cu^{2+}$, and $Fe^{3+}$ under various conditions to identify an intracellular catalyst. Enormous increase by bicarbonate in the rate of $DCFH_2$ oxidation distinguished CuZnSOD from cytochrome c and HRP. Cyanide inhibited the reaction catalyzed by CuZnSOD but accelerated that by $Cu^{2+}$ and $Fe^{3+}$. Oxidation of $DCFH_2$ by $H_2O_2$ in the presence of a cell lysate was also enhanced by bicarbonate and inhibited by cyanide. Confocal microscopy of $H_2O_2$-treated cells showed enhanced DCF fluorescence in the presence of bicarbonate and attenuated fluorescence for the cells pre-incubated with KCN. Moreover, DCF fluorescence was intensified in CuZnSOD-transfected HaCaT and RAW 264.7 cells. We propose that CuZnSOD is a potential intracellular catalyst for the $H_2O_2$-dependent oxidation of $DCFH_2$.

• 실내환경 및 냄새 학회지
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• 제17권4호
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• pp.381-388
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• 2018

In this study, various conditions and phenomena that occur in the process of removing odorous VOCs by using electrolyzed oxidant were examined. The formation of hypochlorous acid, which is an oxidant produced by electrolysis, was investigated and the properties of the oxidizing agent used to decompose toluene, xylene, and cyclohexane were investigated. As a result, it was found that the production rate and the final concentration of the oxidizing agent increased with the current density. It was found that the degree of removal varies depending on the property of each pollutant. Interestingly, in the batch experiments in which the pH of the produced oxidant was controlled, it was found that the degree of elimination varied depending on the pH of the substance. These results suggest that the difference in the concentration and distribution of hypochlorous acid (HOCl) and hypochlorite ($OCl^-$) due to the pH change leads to the difference in oxidizing power on the oxidation characteristics of each substance. Styrene and terpineol showed better degradation characteristics than toluene and xylene in odorous VOC removal experiments by spraying electrolytic oxidant using a lab-scale continuous reactor. In conclusion, the removal of odorous VOCs by the electrolytic oxidant can have various applications in that it can oxidize pollutants of various spectra.

• Journal of Electrochemical Science and Technology
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• 제13권1호
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• pp.1-18
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• 2022

Persistent organic pollutants (POPs) and emerging pollutants (EP) are characterized by their difficulty to be removed through biological oxidation processes (BOPs); they persist in the environment and could have adverse effects on the aquatic ecosystem and human health. The electro-oxidation (EO) process has been successfully used as an alternative technique to oxidize many kinds of the aforementioned pollutants in wastewater. However, the EO process has been criticized for its high energy consumption cost and its potential generation of by-products. In order to decrease these drawbacks, its combination with biological oxidation processes has been reported as a solution to reduce costs and to reach high rates of recalcitrant pollutants removal from wastewaters. Thus, the location of EO in the treatment line is an important decision to make, since this decision affects the formation of by-products and biodegradability enhancement. This paper reviews the advantages and disadvantages of EO as a pre and post-treatment in combination with BOPs. A perspective of the EO scale-up is also presented, where hydrodynamics and the relationship of A/V (area of the electrode/working volume of the electrochemical cell) experiments are examined and discussed.

• 한국재료학회지
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• 제32권11호
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• pp.458-465
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• 2022

Interest in the use of semiconductor-based photocatalyst materials for the degradation of organic pollutants in a liquid phase has grown, due to their excellent performance and response to the light source. Herein, we fabricated a NiO-SiC-TiO₂ ternary structured photocatalyst which had reduced bandgap energy, with strong activation under UV-light irradiation. The synthesized samples were examined using XRD, SEM, EDX, TEM, DRS, EIS techniques and photocurrent measurement. The results confirmed that the two types of metal oxides were well bonded to the SiC fiber surface. The junction of the new photocatalyst exhibited a large number of photoexcited electrons and holes. The holes tended to oxidize the water and form a hydroxyl radical, which promoted the decomposition of methylene blue. The close contact between the 2D SiC fiber and metal oxide semiconductors expanded the scope of absorption wavelength, and enhanced the usability of the ternary photocatalyst for the degradation of methylene blue. Among three synthesized samples, the NiO-SiC-TiO₂ showed the best photocatalytic effect, and was considered to have excellent photoelectron transfer due to the synergy effect between the metal oxide and SiC.

• 방사성폐기물학회지
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• 제21권1호
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• pp.43-53
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• 2023

Sulfide concentrations critically affect worker safety and the integrities of underground facilities, such as deep geological repositories for spent nuclear fuel. Sulfide is highly sensitive to oxygen, which can oxidize sulfide to sulfate. This can hinder precise measurement of the sulfide concentration. Hence, a literature review was conducted, which revealed that two methods are commonly used: the methylene blue and sulfide ion-selective electrode (ISE) methods. Inductively coupled plasma optical emission spectroscopy (ICP-OES) was used for comparison with the two methods. The sulfide ISE method was found to be superior as it yielded results with a higher degree of accuracy and involved fewer procedures for quantification of the sulfide concentration in solution. ICP-OES results can be distorted significantly when sulfide is present in solution owing to the formation of H₂S gas in the ICP-OES nebulizer. Therefore, the ICP-OES must be used with caution when quantifying underground water to prevent any distortion in the measured results. The results also suggest important measures to avoid problems when using ICP-OES for site selection. Furthermore, the sulfide ISE method is useful in determining sulfide concentrations in the field to predict the lifetime of disposal canisters of spent nuclear fuel in deep geological repositories and other industries.

• Nutritional Sciences
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• 제6권3호
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• pp.155-159
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• 2003

Ninety rats were fed either a control diet or one of several allium vegetable diets (allium sativum (AS), allium cepa (AC), allium fistulosum (AF) or aliium tuberosum (AT) for 4 weeks and were separated into 3 groups : non-exercise (NE), exercise (EX), and exercise and recuperation (ER), The EX group was exercised on a treadmill for 1 hour just before sacrifice at the end of 4th week of diet intake and the ER group was recuperated for 2 hours after exercise. The levels of glucose (GLU), (PRO), triglyceride (TG), free fatty arid (FFA) and hemoglobin (Hb) were compared in plasma. In the U group, GLU levels of AS and AC tended to be higher than those of the control group. There were no differences in GLU levels between the control group and the allium vegetable groups in EX, whereas GLU levels of AS, AF and AT tended to be lower than that of control group in ER. There were no differences in PRO among the groups NE, EX and ER. TG and EEh levels of AS, AC, AF and AT tended to be lower than those of the control group in NE, EX and ER. Hb levels of AS, AC, AF and AT were lower than that of the control group in U and ER and tended to be lower than that of EX. These results suggest that allium vegetable diets have the potential to enhance the capacity to oxidize fatty acid and to recover triglyceride after recuperation, although there is compensation among stored fuel utilization during exercise

• 자원리싸이클링
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• 제28권6호
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• pp.18-25
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• 2019

폐니켈수소전지에 함유되어 있는 세륨을 회수하기 위하여 침출 및 침전을 통해 회수한 희토류복합 침전분말을 수산화나트륨(NaOH) 수용액에 반응온도 70 ℃ 및 반응시간 4시간의 조건에서 이온치환반응을 통하여 희토류 수산화물로 변환시켰다. 이후 희토류 수산화물은 반응온도 80 ℃에서 반응시간 4시간의 조건에서 공기를 주입하며 산화반응을 통해 세륨을 Ce³⁺에서 Ce⁴⁺로 전환시켰다. 세륨의 산화율은 XPS 분석을 통해 약 25 %로 확인하였으며, 산화반응이 완료된 분말은 묽은 황산에 대한 용해도 차이를 이용하여 세륨과 나머지 희토류를 분리하였다. 최종적으로 회수된 분말은 XRD 분석을 통해 수산화세륨(Ce(OH)₄)의 결정상을 확인하였으며, 이때 세륨의 순도는 약 94.6 %, 회수율은 97.3 %를 나타내었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.190.1-190.1
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• 2016

One of the most serious problems faced by billions of people today is the availability of fresh water. According to statistics, 15% of the world's total output of dye products is discharged into the environment as dye wastewater, which seriously pollutes groundwater resources. For the treatment of chemically and biologically contaminated water the advanced oxidation processes (AOPs) shows the promising action. The main advantage with AOPs is the ability to degrade the organic pollutants to $CO_2$ and $H_2O$. For this degradation process the AOPs generation of powerful and non-selective radicals that may oxidize majority of the organic pollutants present in the water body. To generate the various reactive chemical species such as radicals (${\bullet}OH$, ${\bullet}H$, ${\bullet}O$, ${\bullet}HO_2$) and molecular species ($H_2O_2$, $H_2$, $O_2$) in large amount in water, we have used the atmospheric pressure plasma. Among the reactive and non-reactive species, the hydroxyl radical (${\bullet}OH$) plays important role due to its higher oxidation potential (E0: 2.8 V). Therefore, in this work we have checked the degradation of various dyes such as methyl orange, methylene blue and congo red using different type of atmospheric pressure plasma sources (Indirect jet and direct jet). To check the degradation we have used the UV-visible spectroscopy, HPLC and LC-MS spectroscopy. Further, to estimate role of ${\bullet}OH$ on the degradation of dyes we have studied the molecular dynamic simulation.

• 생명과학회지
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• 제13권1호
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• pp.47-53
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• 2003

본 연구는 폐수 중의 질소 제거를 위한 생물학적 처리용 미생물 개발을 위한 목적으로 유류 분해 능력이 뛰어난 균 주인 Bacillus sp. A8-8을 사용하여 수질 중의 질소 산화능을 조사하였다. 사용한 균주는 0.5% 포도당이 포함된 초기 pH가 7.0인 암모니아성 질소 및 아질산성 질소 함유 배지에서 12시간 배양 후 각각 약 95.5%와 85%의 암모니아성 질소와 아질산성 질소의 감소율을 나타내었다. 산업 폐수 및 생활 하수에 분리 균 주를 이용한 결과, 수질 속의 암모니아성 질소가 단시간에 크게 감소시키는 효과를 확인하였다. 균 주를 고정시킨 담체의 질소 산화 효과를 시험하고자 Bacillus sp. A8-8을 고정시킨 세라믹 담체를 이용한 결과, 배양 1일 후에는 암모니아성 질소가 전부 제거되었다.

• 한국물환경학회지
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• 제23권3호
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• pp.319-323
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• 2007

The Advanced Oxidation Process (AOP) is being increasingly used to oxidize complex organic constituents in treated effluents from domestic wastewater treatment plants. Generally, ${NO_3}^--N$ concentrations ranges between 5 and 8 mg/L for biologically well-treated effluents. However, nitrate ions, ${NO_3}^-$, affects on oxidation as not only a well-known strong absorber of UV light below 250 nm of wavelength but also as an OH radical scavenger. The objective of this study was to evaluate the AOP systems for degradation of 2,4-DCP, and to delineate the effect of nitrate ions on UV oxidation of 2,4-DCP by conducting a bench-scale operation at various reaction times and initial concentrations of $H_2O_2$. The experimental results indicated that 2,4-DCP could be completely oxidized by $UV/H_2O_2$ process with an initial $H_2O_2$ concentration of 20 mg/L at a retention time of 1.0 min or longer. Nitrate ions did not show any adverse effect on 2,4-DCP oxidation at this high $H_2O_2$ concentration, and the practical initial $H_2O_2$ concentration and reaction time for the 80% oxidation turned out to be 5 mg/L and 1.0 min, respectively.