• Journal of Conservation Science
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• v.27 no.4
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• pp.345-356
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• 2011

To remove metal stains of the ceramics, chemical cleaning is essential case by case. This study investigated the removal characteristics of iron stains by oxalic acid and citric acid including their application methods of soaking and poultice. The soaking method in cleaning agents showed removal process by color difference and released iron contents from iron stains on ceramics. Iron stains were removed successfully from ceramics, which soaked in oxalic acid for 60 hours. However, it is recommendable to soak in 0.25M oxalic acid for one to three hours because most iron stains were disappeared in 3 hours soaking. Citric acid is less effective than oxalic acid in removing iron stains because of heavy molecular weight and low acidity. Poultices (bentonite, sepiolite, activated carbon fiber and celite) with oxalic acid were applied on contaminated ceramics. After ten hours, iron stains on ceramics were removed successfully by poultice. Among them, bentonite and sepiolite have better application. Therefore, sepiolite with 0.25M oxalic acid was applied on the iron stains of whiteware and celadon from Ma Island, and then stains were removed. However, it is judged that the application methods can be varied according to the form and depth of contaminant. In addition, the residues of poultice on the ceramics will be considered for preventing contamination.

• Applied Chemistry for Engineering
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• v.24 no.6
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• pp.656-662
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• 2013

The iron oxide ($Fe_3O_4$) particles in the coolant of the secondary system of a nuclear power plant reduce the heat transfer performance or induce corrosion on the surface of the heat transfer tube. To prevent these problems, we conducted a study to improve the dispersion stability of iron oxide using polymeric dispersant injection in simulated secondary system water. The three kinds of anionic polymers containing carboxyl groups were selected. The dispersion characteristics of the iron oxide particles with the polymeric dispersants were evaluated by performing a settling test and measuring the transmission, the zeta potential, and the hydrodynamic particle size of the colloid solutions. Polymeric dispersants had a significant impact on the iron oxide dispersion stability in an aqueous solution. While the dispersant injection tended to improve the dispersion stability, the dispersion stability of iron oxide did not increase linearly with an increase in the dispersant concentration. This non-linearity is due to the agglomerations between the iron oxide particles above a critical dispersant concentration. The effect of the dispersant on the dispersion stability improvement was significant when the dispersant concentration ratio (ppm, dispersant/magnetite) was in the range of 0.1 to 0.01. This suggests that the optimization of dispersant concentration is required to maximize the iron oxide removal effect with the dispersant injection considering the applied environments, the iron oxide concentration and the concentration ratio of dispersant to iron oxide.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.3
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• pp.127-133
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• 2009

In order to determine organic carbon oxidation by manganese and iron oxides, six core sediments were obtained in slope and basin sediments of Ulleung Basin in East Sea. The basin sediments show high organic carbon contents (>2%) at the water depths deeper than 2,000 m; this is rare for deep-sea sediments, except for those of the Black Sea and Chilean upwelling regions. In the Ullleung Basin, the surface sediments were extremely enriched by Manganese oxides with more than 2%. Maximum contents of Fe oxides were found at the depth of $1{\sim}4cm$ in basin sediments. However, the high level of Mn and Fe oxides was not observed in slope sediment. Surface manganese enrichments (>2%) in Ulleung Basin may be explained by two possible mechanisms: high organic carbon contents and optimum sedimentation rates and sufficient supply of dissolved Manganese from slope to the deep basin. Reduction rates of iron and manganese oxides ranged from 0.10 to $0.24\;mmol\;m^{-2}day^{-1}$ and from 0.30 to $0.57\;mmol\;m^{-2}day^{-1}$, respectively. In Ulleung Basin sediments, $13{\sim}26%$ of organic carbon oxidation may be linked to the reduction of iron and manganese oxides. Reduction rates of metal oxides were comparable to those of Chilean upwelling regions, and lower than those of Danish coastal sediments.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.318-321
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• 2003

비소로 오염된 토양, 하천 퇴적물 및 광미의 복원할 때, 토양 세척 공정에서 중요한 인자인 비소의 화학적 결합형태와 세척제에 따른 용출특성과 고효율 세척 및 세척액의 재활용도를 높이기 위한 공정을 바탕으로 토양세척장비를 설계하였다. 화학적 결합형태에 있어서 토양은 잔류 결합형태가 주되고, 퇴적물의 경우는 철산화물과의 결합형태가 강하며, 광미는 황화물과의 결합에 따른 잔류형태와 철산화물과의 결합형태가 상당부분을 차지한다. 세척제에 따른 용출특성으로부터, 철산화물과 황화물과 결합하고 있는 비소의 화학적 결합형태를 파괴하면서 비소를 추출할 수 있는 용제로 HCl, Oxalate, EDTA, M$_2$O$_2$를 사용하였다. 추출 결과, 비소가 철산화물과 결합한 형태가 비중이 높을수록 EDTA 나 Oxalate가 효율이 높으며, 황화물에 대해서는 HCl과 $H_2O$$_2$이 상대적으로 높은 추출 효율을 보였다. 구성된 세척조는 밀폐실린더형과 스크류이송형 세척조로 구성되어 각각 혼합교반에 의한 세척과 토양입자 분급에 따른 세척이 가능하다. 세척 공정중 최적 산도 조절이 중요한 인자가 되며, 세척액의 재활용도를 높일때, 세척수에 용해되어 있는 비소 및 중금속과 미립자의 동시 제거를 위한 응집 침전조에서 응집제에 의해서 미립자와 함께 제거하는 응집, 침전 및 분리공정을 배치하였다.

• Journal of the Korean Magnetics Society
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• v.24 no.5
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• pp.135-139
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• 2014

Iron-oxide nanopowders were synthesized by a pulsed wire evaporation (PWE) in various ambient gas conditions. SEM measurement indicates that the spherical iron nanoparticles are about 50 nm in diameter. The phase analysis for the produced iron-oxide powders was systematically investigated by using $M\ddot{o}ssbauer$ spectra and the results show that classified phases of $Fe_2O_3$ and $Fe_3O_4$ can be controlled by regulating the oxygen concentration in the mixed gas during the PWE process. A quadrupole line on the center of $M\ddot{o}ssbauer$ spectrum represents the superparamagnetic phase of 12 % from ${\gamma}-Fe_2O_3$ phase.

• Economic and Environmental Geology
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• v.43 no.6
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• pp.543-553
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• 2010

This study was focused on the mineralogical and geochemical characteristics of field soil of the Baekje Kingdom from K wongbawigol site in Jeongdongri, Buyeo and whether the bricks from Songsanri Tombs and Muryung's Royal Tomb were made of soil from this site. Soil samples show the similar size fraction as a silt loam and acidic soil, whereas some samples have the enrichment of organic matter, P and S. Also, they have similar geochemical behavior of elements and similar mineral phases consisting of quartz, plagioclase, orthoclase, vermiculite, mica and kaolinite. The enrichment of iron oxide is found in some soil layer, including the iron oxide mottling and precipitation along plant roots and they are attributed to repeat oxidation and reduction environments due to flooding and drainage of field soil. It's anthropogenic alteration by human activity. Especially, it is assumed that the concentration of the iron oxides found in bricks from Muryung's Royal Tomb and Songsanri Tombs is the additional evidence that soil in this study is probably the raw materials of those bricks.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.3 no.3
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• pp.198-202
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• 2002

Ethanolamine (ETA), instead of ammonia, increases pH in the secondary system water and inhibits the corrosion of iron, which improves the integrity of the steam generator tubes. The different physicochemical properties of ETA from ammonia provide the different effect on the dissolution and adsorption of corrosion products entering the steam generator and thus on the hideout returns of ionic impurities in the steam generator sludge pile. The objective of this study was to investigate those properties with increasing temperature. ETA is more adsorbed onto the iron oxides, which increases the solubility of them and also lowers the hideout returns due to the reduced impurities adsorbed.

• Journal of Conservation Science
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• v.35 no.6
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• pp.573-587
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• 2019

In this study, reproducing specimens were made from mixing domestically produced magnetite, clay and non-plastic raw materials to reproduce the pigments used in the manufacture of traditional cheolhwa buncheong stoneware. In order to reveal the color fomation of glaze, 30 specimens with good color development were analyzed scientifically. Magnetite, which is the main raw material of the pigment, is a pigment capable of creating a dark black color in a reducing environment at 1,200℃. However, it reacts with the additionally added lime component and discolors to greenish yellow color in oxidizing environment at 1,230℃. Hematite is not significantly affected by the firing temperature and environment, but develops a dark black color when mixed with clay with iron content of more than 10%. The fluidity of the pigment is determined by R₂O₃/RO₂ value, which also affects the color development. In the microtexture observation, the color formation of the glaze layer and the iron oxide crystals identified some differences depending on the particle size of the pigment and the firing environment. Reproduced specimens made of magnetite are present in the form of aggregates of iron oxide in the interface between glaze layer and slip layer in the oxidizing environment at 1,200℃. However, in the reducing environment, aggregates of iron oxides do not exist in the reproduced specimens, and they are homogeneously distributed in the glaze layer and formed a dark black color. In contrast, hematite-based specimens form dendritic structures in the glaze layer in an oxidizing environment and develop black.

• Journal of Conservation Science
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• v.36 no.5
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• pp.393-404
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• 2020

We observed changes in the properties of the glaze layer according to the content of iron oxide and inferred the composition, content, and environment of the materials used in the past during the production process of black ware. First, experiments were conducted using different ratios of iron oxide, feldspar, calcite, and ash at different temperatures and firing environments; the characteristics of glaze were classified into five groups in the oxidation environment. Different properties were identified in the reducing environment above 1200℃. The crystal identified in the experiment was similar to the glaze characteristics in the excavated black ware. The crystal phase appeared in four groups: band shape, circular, arborescent phase, and needle crystal, depending on the change in the content of iron oxide. However, the difference in crystals did not appear significantly at high temperatures. In addition, crystals of glaze were divided into two groups depending on the component ratio. The presence or absence of feldspar is thought to affect crystallinity and amorphous iron oxide and the changes in the glaze layer changed substantially depending on the amount of iron oxide. In particular, it was confirmed that the aspects of iron oxide in the oxidation and reduction environments were different and, therefore, crystallization due to the firing environment also affected the optical characteristics.

• Resources Recycling
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• v.21 no.1
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• pp.75-81
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• 2012

Porous pellets for immobilizing heavy metals were manufactured from coal tailings and iron oxide powder. Coal tailings was pulverized and mixed with iron oxide powder. The mixed powder was granulated into spherical pellets and roasted. Over $1100^{\circ}C$, residual coal in coal tailings reduced iron oxide to ZVI(Zero-Valent Iron). The pellets have 34.63% of porosity, 1.31 g/mL of bulk density, and 9.82.urn median pore diameter. The pellets were reacted with synthetic solutions containing each heavy metals: arsenic(V), copper(II), chrome(VI), and cadmium(II), respectively. On the test of immobilizing heavy metal, the pellets made at $1100^{\circ}C$ were superior to the other pellets made under $1000^{\circ}C$. Immobilizing over 99.9% of 10ppm heavy metal solutions required I hour for arsenic, 2 hours for chrome, and 4 hours for copper. However, immobilizing capacity of cadmium was inferior to that of the other metals and it was decreased in reversely proportion to initial concentration of the solutions.