• Analytical Science and Technology
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• v.23 no.6
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• pp.560-565
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• 2010

Perchlorate ion ($ClO_4^-$) has been widely used as oxidizing agent in military weapon system such as rocket and missile fuel propellant. So it has been challenging to remove the pollutant of perchlorate ion. nanoscale zero valence iron (nZVI) particles are widely employing reduction catalyst for decomposition of perchlorate ion. nZVI particles has increasingly been utilized in groundwater purification and waste water treatment. But it have strong tendency of aggregation, rapid sedimentation and limited mobility. In this study, we focused on reduction of perchlorate ion using nZVI particles immobilized in alginate polymer bead for stabilization. The stabilized nZVI particles displayed much greater surface area, and much faster reaction rates of reduction of perchlorate ion. In this study, an efficient way to immobilize nZVI particles in a support material, alginate bead, was developed by using $Ca^{2+}$ as the cross-linking cations. The efficiency and reusability of the immobilized Fe-alginate beads on the reduction of perchlorate was tested at various temperature conditions.

• Corrosion Science and Technology
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• v.16 no.4
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• pp.187-193
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• 2017

Polymer amines are found to show distinct corrosion inhibition effects in acidic media. The functional groups of organic compounds have a wide role in the physical and chemical properties, for the inhibition efficiency with respect to steric factors, aromaticity, and electron density. The influence of $H^+$ ions and $Cl^-$ ions on the corrosion inhibitive effect of poly(p-aminophenol) for iron in hydrochloric acid was studied using electrochemical methods such as impedance, linear polarization, and Tafel polarization techniques. The experiments were conducted with and without the inhibitor, poly(p-aminophenol). The concentration range of $H^+$ ions and $Cl^-$ ions are from 1 M to 0.05 M and 1 M to 0.1 M, respectively. With the inhibitor poly(p-aminophenol), this study shows that inhibition efficiency decreases with the reduction of $H^+$ ion and $Cl^-$ ion concentrations in aqueous solution. Further, it reveals that the adsorption of an inhibitor on the surface of iron is dependent on the concentrations of $H^+$ and $Cl^-$ ions in the solution and the adsorption of inhibitor on the iron surface through the cationic form of amine.

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2577-2583
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• 2009

Presented are the formation of iron oxide layers on evaporator tubes in an actual fossil power plant operated under all volatile treatment (AVT) condition and an experimental simulation of iron oxide formation in the presence of ferrous and ferric ions. After actual operations for 12781 and 36326 hr in the power plant, two iron oxide layers of magnetite on the evaporator tubes were found: a continuous inner layer and a porous outer layer. The experimental simulation (i.e., artificial corrosion in the presence of ferrous and ferric ions at 100 ppm level for 100 hr) reveals that ferrous ions turn the continuous inner oxide layer on tube metal to cracks and pores, while ferric ions facilitate the production of porous outer oxide layer consisting of large crystallites. Based on a comparison of the oxide layers produced in the experimental simulation with those observed on the actually used tubes, we propose possible routes for oxid layer formation schematically. In addition, the limits of the proposed corrosion routes are discussed in detail.

• Journal of the Korean Chemical Society
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• v.47 no.2
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• pp.115-120
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• 2003

Determination of iron(II) ion with a perfluorinated sulfonated polymer(nafion)-ethylenediamine(en) modified glassy carbon electrode was studied. It was based on the chemical reactivity of an immobilized layer(nafion-en) to yield complex $[Fe(en)_3]^{+2}$. The oxidation peak potential by differential pulse voltammetry(DPV) was observed at 0.340${\pm}$0.015 V(vs. Ag/AgCl). The linear calibration curve was obtained in iron(II) ion concentration range $5{\times}10^{-6}{\sim}0.2{\times}10^{-3} M(0.28{\sim}11.17\; mg/L)$, and the detection limit(3s) was $1.89{\times}10^{-5}$M(1.056 mg/L).

• Korean Chemical Engineering Research
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• v.59 no.1
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• pp.49-53
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• 2021

The Fenton reaction is often used to evaluate the chemical durability of polymer membranes of Proton Exchange Membrane Fuel Cells (PEMFC). However, due to the violent reaction between hydrogen peroxide and iron ions, it is difficult to compare experimental data because of low reproducibility. In this study, we tried to find the reaction conditions to improve the reproducibility of the durability test of the membrane by the Fenton reaction. The hydrogen peroxide concentration was fixed at 30%, the iron ion concentration, temperature, stirring speed, and sample size were varied, and the fluorine ion concentration of the Nafion polymer membrane deteriorated by radicals was measured. When the iron ion concentration was increased or the membrane sample size was increased, and the reaction temperature was increased to 80 ℃, the experimental deviation increased, so an iron ion concentration of 10 ppm, a temperature of 70 ℃, and a sample size of 0.5 ㎠ were suitable.

• Journal of the Korean Ceramic Society
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• v.48 no.2
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• pp.117-120
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• 2011

In this study, the redox state of iron in sodium silicate glasses was varied by changing the melting conditions, such as the melting temperature and particle size of iron oxide. The oxidation states of the iron ion were determined by wet chemical analysis and UV-Vis spectroscopy methods. Iron commonly exists as an equilibrium mixture of ferrous ions, $Fe^{2+}$, and ferric ions $Fe^{3+}$. In this study, sodium silicate glasses containing nanoparticles of iron oxide (0.5% mol) were prepared at various temperatures. Increase of temperature led to the transformation of ferric ions to ferrous ions, and the intensity of the ferrous peak in 1050 nm increased. Nanoparticle iron oxide caused fewer ferrous ions to be formed and the $\frac{Fe^{2+}}{Fe^{3+}}$ equilibrium ratio compared to that with micro-oxide iron powder was lower.

• Archives of Pharmacal Research
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• v.22 no.3
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• pp.288-293
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• 1999

Postabsorptive serum iron level was determined after oral administration of the compounds to human. In serum and whole blood, $Fe^{3+}$ was measured by ion chromatography (IC) using a pyridine-2,6-dicarboxylic acid (PDCA) as an eluent. The serum sample solutions were pretreated with I N HCI and 50% TCA. The whole blood sample solutions were treated with 3 N HCI for 30 min at $125^{\circ}C$. The limit of detection (LOD) of the IC technique is $0.2 {\mu}M$ for$Fe^{2+}$and 0.1 $\mu$M for $Fe^{3+}$. The area under concentration (AUC) can be obtained by the above analytical condition. In addition, to compare the stability of $Fe^{2+}$ to that of $Fe^{3+}$ in pharamaceutical preparations, accelerated stability test was carried out. After storing the samples under $40^{\circ}C$, 75%RH in light-resistant container for various time intervals, the contents of iron of different valencies were determined separately by the IC technique and the change and/or the interchange of among those iron species in preparations was investigated. Iron raw materials are stable, but $Fe^{2+}$ in$Fe^{3+}$ source materials was slightly converted to $Fe^{3+}$ by oxidation. $Fe^{2+}$ in$Fe^{3+}$ source raw materials and $Fe^{3+}$ in $Fe^{2+}$ raw materials are determined as impurities. Therefore, IC technique is found to be an appropriate method for comparative evaluation of dissimilar bioavailability of $Fe^{2+}$ and $Fe^{3+}$, stability of $Fe^{2+}$ and $Fe^{3+}$ raw materials and preparations.

• Journal of Korean Society for Atmospheric Environment
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• v.7 no.2
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• pp.137-142
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• 1991

A method is developed for the simultaneous determination of dissolved iron, copper, and zinc in rainwater. The method involves 25-fold evaporative concentration, ion chromatographic separation and subsequent spectrophotometric detection after post-column reaction with 4-(2-pyridylazo) resorcinol. Analytical sensitivities, being defined by the slopes of calibration curves, are 0.93, 0.54, and 0.11 Abs/ $\mu$g/ml for iron, copper, zinc, respectively. Detection limits render around a few tenth of one ng/ml. Precisions evaluated by replicate analysis of real sample are better than 10% RSD. Due to the lack of certified standards for rainwater, the accuracy of the method could not be assessed directly. However, the results of this method agree well with those by inductively coupled plasma mass spectrometry. Analytical results for a suite of Seoul rainwaters are presented herein.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.2
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• pp.220-228
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• 2017

Effects of extraction methods on reducing concentrations of pro-oxidants (total iron and protein) of salmon was determined. For development of the extraction process, the effectiveness of several extraction methods was determined and compared, including heat treatment (60, 80, and $100^{\circ}C$), ion exchange and carboxymethyl (CM)-cellulose column chromatography, and ultrafiltration (UF). Protein, total iron, and anserine contents of salmon extracts were 23.64 mg/mL, $16.20{\mu}g/mL$, and 5.47 mg/mL in non-heated extracts, 7.40 mg/mL, $2.32{\mu}g/mL$, and 5.20 mg/mL in heated extracts at $60^{\circ}C$, 7.64 mg/mL, $1.20{\mu}g/mL$, and 5.21 mg/mL at $80^{\circ}C$, and 7.04 mg/mL, $0.68{\mu}g/mL$, and 4.04 mg/mL at $100^{\circ}C$, respectively. Heating and UF decreased contents of protein and total iron, whereas only UF slightly decreased anserine content. Application of the primary ion exchange method increased the content of anserine up to 16%. Protein and total iron contents by the primary ion exchange method decreased by 70 and 98%, respectively. Secondary ion exchange (CM-cellulose) treatment after primary ion exchange and UF resulted in lower anserine content than the primary ion exchange method. However, the content of impurities (protein, total iron) was lower than in all other salmon extracts. Therefore, primary ion exchange, UF, and secondary ion exchange method were the best extraction processes in this study.

• Journal of the Korean Ceramic Society
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• v.53 no.3
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• pp.376-380
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• 2016

A composite electrode made of iron oxide nanoparticles/multi-wall carbon nanotube (iNPs/M) delivers high specific capacity and cycle durability. At a rate of $200mAg^{-1}$, the electrode shows a high discharge capacity of ${\sim}664mAhg^{-1}$ after 100 cycles, which is ~ 70% of the theoretical capacity of $Fe_3O_4$. Carbon black, carbon nanotube, and graphene as anode materials have been explored to improve the electrical conductivity and cycle stability in Li ion batteries. Herein, iron oxide nanoparticles on acid treated MWCNTs as a conductive platform are combined to enhance the drawbacks of $Fe_3O_4$ such as low electrical conductivity and volume expansion during the alloying/dealloying process. Enhanced performance was achieved due to a synergistic effect between electrically 3D networks of conductive MWCNTs and the high Li ion storage ability of $Fe_3O_4$ nanoparticles (iNPs).