• Corrosion Science and Technology
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• v.7 no.3
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• pp.182-186
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• 2008

The microstructures of the oxide scale developed at high temperature on steels are very complex and their development depends on many factors including time, temperature, oxidation conditions and alloying elements. The classical model of an oxide scale on steel consisting of wüstite, magnetite and haematite layers, is more complicated in reality and its properties change with the factors that affect their development. An understanding of the oxide scale formation and its properties can only be achieved by careful examination of the scale microstructure. The oxide scale microstructure may be difficult to characterise by conventional techniques such as optical or standard scanning electron microscopy. An unambiguous characterisation of the scale and the correct identification of the phases within the scale are difficult unless the crystallographic structure for each phase in the scale is considered and a simultaneous microstructure-microtexture analysis is carried out. In the current study Electron Backscatter Diffraction (EBSD) has been used to investigate the microstructure of iron oxide layers grown on low carbon steels at different times and temperatures. EBSD has proved to be a powerful technique for identifying the individual phases in the oxide scale accurately. The results show that different grain shapes and sizes develop for each phase in the scale depending on time and temperature.

• Transactions of Materials Processing
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• v.26 no.6
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• pp.365-371
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• 2017

During sling wear of a ferrous metal, a surface layer is formed. Its microstructure, constituting phases, and mechanical property are different from those of the original wearing material. Since wear occurs at the layer, it is important to characterize the layer and understand how wear rate changes with different layers. Various layers are formed depending on external wear conditions such as load, sliding speed, counterpart material, and environmental conditions. In this research, sliding wear tests of pure iron were carried out against two different counterparts (AISI 52100 bearing steel and $Al_2O_3$) in the air and in an inert Ar gas atmosphere. Pure iron was employed to exclude other effects from secondary phases in steel on the wear. Wear tests were performed at room temperature. Worn surfaces, wear debris, and cross-sections were analyzed after the test. It was found that these two different counterparts and environments produced diverse layers, resulting in significant changes in wear rate. Against the bearing steel, pure iron showed higher wear rate in an Ar atmosphere due to severe adhesion than that in the air. On the contrary, the iron showed much higher wear rate in the air against $Al_2O_3$. Different layers and wear rates were analyzed and discussed by oxidation, severe plastic deformation, and adhesion at wearing surfaces.

• Clean Technology
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• v.18 no.2
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• pp.183-190
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• 2012

Electrochemical regeneration of the iron chloride waste solution from PCB etching reduces environmental contamination and produces copper as by-product, so the economic feasibility is high. But iron chloride waste solution contains iron and copper and the reactions occurring in the electrolytic cell are complicated. In this work, the oxidation of iron chloride and copper deposition were examined through batch electrolysis and the optimum conditions of the process parameters were found. The oxidation of ferrous chloride was achieved easily to the desired level. The copper deposition efficiency was high in the reaction using the carbon cathode when the copper density was 12 g/L with the electric current density of $350mA/cm^2$, and the ratio of the $Fe^{2+}$ ion was high. In addition, the possibility of the scale-up was confirmed in continuous operation of bench reactor using the optimum conditions obtained.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.527-534
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• 1999

This study was carried out to investigate the effects of pine needle extracts on lipid oxidation and free radical reaction in iron sources reacted with active oxygen species. The results were summarized as follow; the catalytic effects of active oxygen on lipid oxidation in oil emulsion tended to be showed $OH,\;H_2O_2\;and\;KO_2$ in order. At the same time, pine needle extracts itself were tended to be showed a little catalytic effects. Active oxygen scavenging ability of pine needle extracts didn't show, but pine needle extracts played role as a strong chelating agents to bind iron ion if $Fe^{2+}$ ion exist in oil emulsion. The content of $Fe^{2+}$ ion and total iron in CPNP were higher than those of HPNP and FPN. The content of ascorbic acid of FPN showed the highest (87.77 ppm) among several pine needle extracts. Electron donating ability of HPNP and CPNP were 81% and 78%, respectively, which were showed higher content than those of FPN. The SOD-like activity of HPNP showed 44.30%, compared to other pine needle extracts which means the most strong antioxidant reaction. The nitrite scavenging effects were tended to be different, depending on pH value as pH value was increased. Especially, they didn't show the nitrite scavenging effect in pH6.0.

• 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 Ceramic Society
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• v.29 no.12
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• pp.942-948
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• 1992

Ultrafine iron oxide powder, {{{{ gamma }}-Fe2O3 and $\alpha$-Fe2O3, were prepared by the thermal decomposition of organometallic compounds. The formation process of powder includes the thermal decomposition and oxidation of the organometallic precursors, Fe(N2H3COO)2(N2H4)2 (A) and N2H5Fe(N2H3COO)3.H2O (B). The organometallic precursors, A and B, were synthesized by the reaction of ferrous ion with hydrazinocarboxylic acid, and characterized by quantitative analysis and infrared spectroscopy. The mechanistic study for the thermal decomposition was performed by DAT-TG. The iron oxide powder was obtained by the heat treatment of the precursors at 20$0^{\circ}C$ and $600^{\circ}C$ for half an hour in air. The phases of the resulting product were proved {{{{ gamma }}-Fe2O3 and $\alpha$-Fe2O3 respectively. The particle shape was equiaxial and the particle size was less than 0.1 ${\mu}{\textrm}{m}$. Magnetic properties of the {{{{ gamma }}-Fe2O3 powder obtained from A and B was 234 Oe of coercivity, 64.26 emu/g of saturation magnetization, 23.59 emu/g of remanent magnetization and 24.1 Oe, 47.27 emu/g, 3.118 emu/g respectively. The value of $\alpha$-Fe2O3 powder was 1.494 Oe, 0.4862 emu/g, 0.1832 emu/g and 1,276 Oe, 0.4854 emu/g, 0.1856 emu/g respectively.

• Journal of Medicine and Life Science
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• v.18 no.1
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• pp.20-23
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• 2021

Methemoglobin is generated by the oxidation of ferrous iron to ferric iron within a hemoglobin molecule. Methemoglobin is unable to bind and transport oxygen, resulting in methemoglobinemia, which can lead to fatal tissue hypoxia. The most common cause of methemoglobinemia is poisoning by oxidizing agents such as dapsone, benzocaine, and primaquine. However, methemoglobinemia can also be caused by normal dietary sources. We present two cases of methemoglobinemia that developed after a normal diet in two male patients. In this case report, the patients suddenly developed dyspnea and cyanosis after eating the same meal. They had no history of suspected poisoning, such as the use of drugs, exposure to chemicals, or gas inhalation. Their symptoms did not improve even after a high dose of oxygen was administered; further, an abnormal 'oxygen saturation gap' was observed. Because of CO-oximetry, the methemoglobin levels of the patients were 50.0% and 46.6%, respectively. We administered methylene blue (1 mg/kg), and the patients recovered completely without any complications. Emergency physicians should, therefore, be aware that methemoglobinemia can also be caused by normal dietary sources. In addition, if the source and route of contamination are unclear, an epidemiological investigation should be conducted.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.145-148
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• 2003

The batch experiments showed that 0.515mM 4-chlorophenol and its oxidation intermediates could be totally decomposed within 60 minutes by 1g/L steelers' dust and 0.485mM hydrogen peroxide at pH 2.7. The rate constants in the simplified kinetic model proposed in this study were estimated by fitting to the experimental data obtained in $H_2O$$_2$/steelers' dust system. Using the estimated kinetic rate constants, the simulation of 4-chlorophenol, ferrous iron, hydrogen peroxide, and hydroxyl radical concentration was performed. The predicted concentrations of 4-chlorophenol and hydrogen peroxide corresponded to the actual concentrations.

• Resources Recycling
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• v.13 no.2
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• pp.9-15
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• 2004

A large tons of spent iron oxide catalyst come from the Styrene Monomer(SM) production company. It is caused to pollute the land and underground water due to the high alkali contents in the catalyst by burying them in the landfill. In order to recycle the spent catalyst, a basic study on the recovery of chromium ion from metal plating wastewater with the spent catalyst was carried out. The iron oxide catalyst adsorbed physically $Cr^{+6}$ in the lower pH 3.0, that is the isoelectric point of the spent catalyst. It was found that the iron oxide catalyst reduced the $Cr^{+6}$ into Cr+3 by the oxidation of ferrous ion into ferric ion on the surface of catalyst, and precipitated as $Cr(OH)_3$ in the higher than pH 3.0. The $Cr^{+6}$ was recovered 2.0∼2.3g/L catalyst in the range of pH 0.5∼2.0, but it was recovered 1.5 g/L catalyst at pH 3.0 of wastewater. The recovery of Cr was increased as the higher concentration in the continuous process, but the flowrates were nearly affected on the Cr recovery.

• Environmental Engineering Research
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• v.19 no.1
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• pp.9-14
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• 2014

Fenton reaction with zerovalent iron (ZVI) and $Fe^{2+}$ ions was studied to treat pharmaceutical wastewaters (PhWW) including antibiotics and non-biodegradable organics. Incremental biodegradability was assessed by monitoring biochemical oxygen demand (BOD) changes during Fenton reaction. Original undiluted wastewater samples were used as collected from the pharmaceutical factory. Experiments were carried out to obtain optimal conditions for Fenton reaction under different $H_2O_2$ and ion salts (ZVI and $Fe^{2+}$) concentrations. The optimal ratio and dosage of $H_2O_2$/ZVI were 5 and 25/5 g/L (mass basis), respectively. Also, the optimal ratio and dosage of $H_2O_2/Fe^{2+}$ ions were 5 and 35/7 g/L (mass basis), respectively. Under optimized conditions, the chemical oxygen demand (COD) removal efficiency by ZVI was 23% better than the treatment with $Fe^{2+}$ ion. The reaction time was 45 min for ZVI and shorter than 60 min for $Fe^{2+}$ ion. The COD and total organic carbon (TOC) were decreased, but BOD was increased under the optimal conditions of $H_2O_2$/ZVI = 25/5 g/L, because organic compounds were converted into biodegradable intermediates in the early steps of the reaction. The BOD/TOC ratio was increased, but reverse-wise, the COD/TOC was decreased because of generated intermediates. The biodegradability was increased about 9.8 times (BOD/TOC basis), after treatment with ZVI. The combination of chemical and biological processes seems an interesting combination for treating PhWW.