• 공업화학
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• 제33권5호
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• pp.482-487
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• 2022

본 연구에서는 V/TiO₂ 촉매를 사용하여 황화수소 상온 제거 특성을 평가하기 위해 촉매 활성 실험 및 특성 분석을 수행하였다. 최적 바나듐 함량은 10 wt%였고, 상대습도 60~80% 조건에서 60분 이상의 내구성을 보였다. BET 및 raman 분석을 통해, 표면에 노출된 바나듐의 구조가 V/TiO₂ 촉매 활성의 지배적인 요인인 것으로 나타났다. 또한 SEM, EDS 그리고 XRD 분석은 촉매 표면에 생성물인 황이 축적될 수 있음을 보였으며, 결과적으로 촉매의 내구성이 감소되었다. 따라서 촉매 산화와 재생 공정의 연계가 필요할 것으로 판단된다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제28권1호
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• pp.15-24
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• 2023

A persulfate(PS)/sulfidated microscale zero-valent iron(S-mZVI) system was tested for treating a soil contaminated with phenol. Sulfidation of bare mZVI was conducted using a mechanochemical process utilizing a ball mill in order to improve persulfate activation capacity and stability of unmodified mZVI. The synthesized S-mZVI performed markedly better than the bare mZVI in activating PS. The optimum molar ratio of sulfur to mZVI was around 0.12. In the soil slurry experiments, a very rapid and complete removal of phenol was observed at the optimum molar ratios of PS to S-mZVI of 2:1 and PS to phenol of 16:1. The phenol removal efficiencies decreased as the water content of the slurries decreased. This was believed to be due to increased soil oxidant demand as the amount of soil was increased as relative to the water content. To evaluate the field applicability of the process, slurry experiments adopting high soil contents were carried out that simulated in-situ soil mixing conditions. These experiments resulted in substantially compromised degradation efficiencies of 54.3% and 43.8% within 4 hours. The current study generally shows that the PS/S-mZVI process has a potential to be developed into a remediation technology for soils contaminated with organics.

• 한국세라믹학회지
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• 제45권2호
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• pp.90-93
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• 2008

The oxygen gas behavior in PDP (plasma Display Panel) glass melts doped with sulfate ($SO_4^{-2}$) or blast furnace slag (BFS, $S^{2-}$) or both by means of yttria-stabilized zirconia (YSZ) electrodes was observed after the first fining. The temperature dependence of oxygen equilibrium pressure ($P_{O2}$) in each melt showed typical behavior, namely $P_{O2}$ decreased as temperature decreased. This suggests that an oxidation of $S^{4+}$ to $S^{6+}$ took place. However, the $P_{O2}$-value at constant temperature increased in the following order: BFS$P_{O2}$ of the melt doped with sulfate+BFS was much lower than that of the melt with only sulfate, although only 10% of sulfur was added by the BFS. This behavior can be explained by the redox reaction between sulfide ions in the BFS and dissolved oxygen ions in the melt during the first fining.

• 한국전기전자재료학회논문지
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• 제17권12호
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• pp.1337-1340
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• 2004

The self-assembled monolayers of alkane derivatives with sulfur containing head groups on gold substrates have been widely examined recently, since the binding between S atoms and Au surface is strong. The viologen has been widely investigated their well-behaved electrochemistry including electron transfer mediation, the surface-enhanced of the adsorption and the behavior of supramolecular assemblies at electrode surfaces in theses and various studies. Yiologen monolayers are formed onto QCM by self-assembly method. We studied the relationship of electron transfer from changing the anions in 0.1 M NaCl and NaClO$_4$ electrolyte solution. The EQCM measurements revealed the anions transfer during reduction and oxidation, respectively From the EQCM data, the well-defined shape peaks were nearly equal charges by cyclic voltammetry.

• KSBB Journal
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• 제28권3호
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• pp.191-195
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• 2013

Cordyceps militaris (CM) occurring from a fruiting body by a host insect is a kind of mushroom, which is composed of animal host and plant fruit body. CM contains large amounts of useful ingredients including polysaccharides, vitamins, amino acids, minerals, etc. The essential amino acids from CM including cystine, lysine, and methionine can be expected to improve damaged hair treatment as effective ingredients. In this study, the improvement effect of the CM extracts on chemical and physical properties for damaged-hair treatment was investigated. The cysteic acid and cystine monooxide produced by oxidation of cystine were analyzed their chemical structure by FT-IR spectroscopy. It was confirmed that the vibration absorption peak ($1,041cm^{-1}$) of cysteic acid was reduced and increased sulfur content considerably which means meaningful improvement effect on damaged-hair treatment. Apparently, the cuticle morphology of the damaged-hair was improved significantly by treatment with CM extracts. Especially, confocal laser scanning microscope images of the damaged-hair treated with the extract showed highly increased fluorescence intensity which means promising effect in hair treatment. The tensile strength of the damaged hair treated also increased by 168% compared with the damaged hair.

• 자원리싸이클링
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• 제27권3호
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• pp.3-7
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• 2018

고품위 산화광의 고갈로 인해 금속황화광의 제련공정의 개발이 중요해지고 있다. 금속황화광의 침출은 대부분 전기화학반응으로 크게 $H_2S$, S, ${SO_4}^{2-}$ 발생형으로 분류된다. 침출용액의 산도와 산화제의 종류 및 농도는 황의 중산생성물 형성에 큰 영향을 미친다. 산화성이 강한 침출용액에서 황 옥소음이온의 Frost도는 황의 산화수가 증가할수록 열역학적으로 안정함을 나타낸다.

• Corrosion Science and Technology
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• 제4권1호
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• pp.19-22
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• 2005

Two Au-Ag-Cu-Pd dental casting alloys (Au:12% and 20%) used. The test solutions used 0.9 % NaCl solution (isotonic sodium chloride solution), 0.9 % NaCl solution containing 1 % lactic acid, and 0.9 % NaCl solution containing 1 % lactic acid and 0.1 mol $dm^{-3}$ $Na_2S$. The surface of two samples in three sample solutions was not natural discoloration during one year. The alloy containing 12 % gold was easily alloyed and the composition was uniform comparing with the alloy containing 20 % gold. The rest potentials have not a little effect after three months. The kinds of metals could not definitely from the oxidation and reduction waves of metal on the cyclic voltammograms. The dissolutions of gold and palladium were 12 % Au sample in the 0.9 % NaCl solution containing 1 % lactic acid and 0.1 mol $dm^{-3}$ $Na_{2}S$. The pH of solution had an affect on dissolution of copper, and sulfur ion had an affect on dissolution of silver. The copper dissolved amount from 20 % gold sample was about 26 times comparing with that of 12 % gold sample in the 0.9 % solution containing 1 % lactic acid. Corrosion products were silver chloride and copper chloride in NaCl solution, and silver sulfide and copper sulfide in NaCl solution containing $Na_{2}S$.

• 한국표면공학회지
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• 제21권2호
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• pp.53-67
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• 1988

The high temperature corrosion of Fe-C alloys were studied at I atm SO gas in the temperature range 500~80$0^{\circ}C$ by means of a thermogravimetric analysis. The Na2SO4 induced high tempwrature corrosion rate was also measured at atm O2 gas under above the temperature renge. The reaction products were identified with the aid of X-ray diffraction technique, and micostruction of the alloy/scale interface was observed with a optical microscope and SEM. The experimental results were disussed by the themodeynamic calcutions. Under above the experimental condition. the reaction rates decrbon with increasing carbon content. The transfer of Fe ion was limited by a residue of carbon precipitated at alloy scale interface due to the oxidation of Fe-C alloys at alloy surface. The effect of cold working on reaction rate was different between the Fe containing low carbon and Fe-C Alloy containing carbon above 0,73 wt%. In a cold worked iron containing low carbon content, the crystallization of metal surface leads to the poor adherence between the alloy and the cavity formed between the alloy and scale. The outward diffusion of ion through the scale is estimated to be hindered by the cavity formed between the scale, consequently decreasing reaction rate. In the case Fe-C containing carbon above 0.73 Wt% alloy, the reaction rate was little affected by cold working, because the effect of content on reaction rats is greater than the effect of cold working.

• Nuclear Engineering and Technology
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• 제37권6호
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• pp.537-556
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• 2005

A primary-pipe rupture accident is one of the design-basis accidents of a High-Temperature Gas-cooled Reactor (HTGR). When the primary-pipe rupture accident occurs, air is expected to enter the reactor core from the breach and oxidize in-core graphite structures. This paper describes an experiment and analysis of the air ingress phenomena and the method fur the prevention of air ingress into the reactor during the primary-pipe rupture accident. The numerical results are in good agreement with the experimental ones regarding the density of the gas mixture, the concentration of each gas species produced by the graphite oxidation reaction and the onset time of the natural circulation of air. A hydrogen production system connected to the High-Temperature Engineering Test Reactor (HTTR) Is being designed to be able to produce hydrogen by themo-chemical iodine-Sulfur process, using a nuclear heat of 10 MW supplied by the HTTR. The HTTR hydrogen production system is first connected to a nuclear reactor in the world; hence a permeation test of hydrogen isotopes through heat exchanger is carried out to obtain detailed data for safety review and development of analytical codes. This paper also describes an overview of the hydrogen permeation test and permeability of hydrogen and deuterium of Hastelloy XR.

• Journal of Preventive Medicine and Public Health
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• 제45권6호
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• pp.335-343
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• 2012

Mercury is emitted to the atmosphere from various natural and anthropogenic sources, and degrades with difficulty in the environment. Mercury exists as various species, mainly elemental ($Hg^0$) and divalent ($Hg^{2+}$) mercury depending on its oxidation states in air and water. Mercury emitted to the atmosphere can be deposited into aqueous environments by wet and dry depositions, and some can be re-emitted into the atmosphere. The deposited mercury species, mainly $Hg^{2+}$, can react with various organic compounds in water and sediment by biotic reactions mediated by sulfur-reducing bacteria, and abiotic reactions mediated by sunlight photolysis, resulting in conversion into organic mercury such as methylmercury (MeHg). MeHg can be bioaccumulated through the food web in the ecosystem, finally exposing humans who consume fish. For a better understanding of how humans are exposed to mercury in the environment, this review paper summarizes the mechanisms of emission, fate and transport, speciation chemistry, bioaccumulation, levels of contamination in environmental media, and finally exposure assessment of humans.