• Journal of Soil and Groundwater Environment
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• v.16 no.6
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• pp.58-65
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• 2011

The bacterial uranium(VI) reduction and its resultant low solubility make this process an attractive option for removing U from groundwater. An impact of aqueous suspending iron phase, which is redox sensitive and ubiquitous in subsurface groundwater, on the U(VI) bioreduction by Shewanella putrefaciens CN32 was investigated. In our batch experiment, the U(VI) concentration ($5{\times}10^5M$) gradually decreased to a non-detectable level during the microbial respiration. However, when Fe(III) phase was suspended in solution, bioreduction of U(VI) was significantly suppressed due to a preferred reduction of Fe(III) instead of U(VI). This shows that the suspending amorphous Fe(III) phase can be a strong inhibitor to the U(VI) bioreduction. On the contrary, when iron was present as a soluble Fe(II) in the solution, the U(VI) removal was largely enhanced. The microbially-catalyzed U(VI) reduction resulted in an accumulation of solid-type U particles in and around the cells. Electron elemental investigations for the precipitates show that some background cations such as Ca and P were favorably coprecipitated with U. This implies that aqueous U tends to be stabilized by complexing with Ca or P ions, which easily diffuse and coprecipitate with U in and around the microbial cell.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.493-500
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• 2003

The effect of reductive treatment with elemental iron on the extent of mineralization by Fenton oxidation was studied for the explosive 2,4,6-trinitrotoluene (TNT) and hexahydro-l,3,5-trinitro-l,3,5-triazine (RDX) using a completely-stirred tank reactor (CSTR). The results support the hypothesis that TNT and RDX are reduced with elemental iron to products that are oxidized more rapidly and completely by Fenton's reagent. Iron pretreatment enhanced the extent of TOC removal by approximately $20\%\;and\;60\%$ for TNT and RDX, respectively. Complete TOC removal was achieved for TNT and RDX solutions with iron pretreatment under optimal conditions. On the other hand, without iron pretreatment, complete mineralization of TNT and RDX solutions were not achieved even with much higher $H_2O_2$ and $Fe^{2+}$ concentrations. The bench-scale iron treatment-Fenton oxidation integrated system showed more than $95\%$ TOC removal for TNT and RDX solutions under optimal conditions. The proposed zero-valent iron-Fenton process was evaluated with pink water from the Iowa Army ammunition plant. Results from batch and column experiments show that TNT, RDX, and octahydro-l,3,5,7-tetranitro-l,3,5,7-tetrazocine (HMX) were completely removed from the pink water and that triaminotoluene (TAT) and ${NH_4}^+$ were recovered as products in reduction with zero-valent iron. By using an integrated system, $83.3\pm4.2\%$ of TOC was removed in a CSTR with 10 mM of $Fe^{2+}$ and 50 mM of $H_2O_2$. These results suggest that the reduction products of TNT and RDX are more rapidly and completely mineralized by Fenton oxidation and that a sequential iron treatment-Fenton oxidation process may be a viable technology for pink water treatment.

• KSBB Journal
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• v.15 no.2
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• pp.208-213
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• 2000

Using three types of porcelain clays such as White, Blue, and Yellow clays, which were used as raw materials for Bae씨a, C Chungja, and common porcelains, the biological refinement by an enrichment culture of iron reducing bacteria was studied. | In the biological clay refining, amounts of leached iron increased as increasing sucrose $\infty$ncentration, which was s supplemented as a carbon and electron donor source for cell growth and iron reduction. Total amounts of the leached iron a and specific rate of iron reduction were dependent on the types of the clay. Strength and chromaticity of refined clays which a are important properties required for porcelain clays were improved as increasing sucrose concentration. The degree of s shrinking, however, did not changed. the redness among the chromaticity of refined clays is favorably reduced through the r ripening by the iron reducing bacteria. Considering iron removal efficiency and the change of physical properties, the optimal c concentration of sucrose was 4%(w/w) in the clay.

• Korean Journal of Heritage: History & Science
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• v.50 no.1
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• pp.4-17
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• 2017

In this research, the chemical composition of the iron artifacts from the late 6th-century to early 7thcentury Baekje remains in Gwanbuk-ri, Buyeo, specifically of the nine iron artifacts including slags, furnace walls and ingot iron excavated in the District "Na", were examined by observing their chemical compounds and microstructures. As a result, GB1 and GB6 were determined to be proto-reduction lumps whereas GB2, GB3, GB4 and GB5 were determined to be tempered slags, respectively. Also, he furnace wall GB7 were containing mullite and cristobalite, which are high temperature index minerals, The extrusion temperature was found out to be about $1200{\sim}1300^{\circ}C$, and it is most likely that the smelting temperature in the furnace was in that temperature range. GB8 ingot iron was determined to be a forged ironware. This ingot iron was an intermediary product for making ironware and its nonmetallic inclusions displayed similar microstructure and contents compared to the forged iron. Because of the existence of proto-reduction lumps and forged iron, the iron making facility located in District "Na" most likely had a small-scale iron making facility that handled iron bloom smelting and refining processes.

• Journal of Environmental Science International
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• v.7 no.4
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• pp.501-504
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• 1998

The role of iron as a possible pathogenic factor in the Infection of V. vulnificus was examined in thins paper The effects of iron and $CCl_4$ on the growth of V. vulnificus in human and rabbit sera were also done. Injection of iron to mice resulted in a lowering of the 50% lethal dose and in a reduction in the time of death postinfection. Serum iron levels were also elevated by damaged livers with infections of $CCl_4$- The inoculum size required to kill these mice was directly correlated with serum iron Irvels. Iron appeared to be the limiting factor In the ability of thins organism to survive or grow in mammalian sera. These results, both in vitro and In vivo, provided strong evidence that iron may play a major role In the pathogenesis of V. vulnificus.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.807-810
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• 2008

Permeable reactive barriers containing Zero-valent iron (ZVI) are used to purify ground-water contaminants. One of the representative contaminant is trichloroethylene (TCE). ZVI can act as a reducing agent of TCE. When ZVI is oxidized to Ferric iron, TCE reduced to Ethene, which is non-harmful matter. As a ZVI becomes ferric iron, the reducing effect decreases and iron becomes unavailable. So, constant reduction of TCE requires the regular supply of reducing agent. So, we use Iron-reducing bacteria(IRB) to extend the TCE degrading ability. We perform three experiment DI water, DI water with medium, and DI water with medium and IRB. By the experiment we try to found the dissolve ability.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.2
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• pp.123-129
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• 2005

In situ permeable reactive barrier (PRB) technologies have been proposed to reductively remove organic contaminants from the subsurface environment. The major reactive material, zero valent iron ($Fe^0$), is oxidized to ferrous iron or ferric iron in the barriers, resulting in the decreased reactivity. Iron-reducing bacteria can reduce ferric iron to ferrous iron and iron reduced by these bacteria can be applied to dechlorinate chlorinated organic contaminants. Iron reduction by iron reducing bacteria, Shewanella algae BrY, was observed both in aqueous and solid phase and the enhancement of TCE removal by reduced iron was examined in this study. S. algae BrY preferentially reduced Fe(III) in ferric citrate medium and secondly used Fe(III) on the surface of iron oxides as an electron acceptor. Reduced iron formed reactive materials such as green rust ferrihydrite, and biochemical precipitation. These reactive materials formed by the bacteria can enhance TCE removal rate and removal capacity of the reactive barrier in the field.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.1
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• pp.21-30
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• 2006

[ $M/Fe_2O_3$ ] (M=Rh, Ce and Zr) mixed oxides were prepared using urea method to develop a medium for chemical hydrogen storage by their redox cycles. And their redox behaviors by repeated cycles were studied using temperature programmed reaction(TPR) technique. Additives such as Rh, Ce and Zr were added to iron oxides in order to lower the reaction temperature for reduction by hydrogen and re-oxidation by water-splitting. From the results, concentration of urea used as a precipitant had little effect on particle size and reduction property of iron oxide. TPR patterns of iron oxide consisted of two reduction peaks due to the course of $Fe_2O_3\;{\rightarrow}\;Fe_3O_4\;{\rightarrow}\;Fe$. The results of repeated redox tests showed that Rh added to iron oxide have an effect on lowering the re-oxidation temperature by water-splitting. Meanwhile, Ce and Zr additives played an important role in prevention of deactivation by repeated cycles. Finally, Fe-oxide(Rh, Ce, Zr) sample added with Rh, Ce and Zr showed the lowest re-oxidation temperature by water-splitting and maintained high $H_2$ recovery in spite of the repeated redox cycles. Consequently, it is expected that Fe-oxide(Rh, Ce, Zr) sample can be a feasible medium for chemical hydrogen storage using redox cycle of iron oxide.

• Resources Recycling
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• v.28 no.3
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• pp.59-67
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• 2019

This study was conducted to fabrication pig iron containing copper and to reduce sulfur content pig iron. Roasting test was conducted for 1 ~ 9 hours at each temperature of $500^{\circ}C$, $700^{\circ}C$, and $900^{\circ}C$. In addition, the effect of oxygen partial pressure with 0.5, 0.8, and 1 atm was carried out for 30 minutes at $900^{\circ}C$. It was found that there is no effect to reduce sulfure in pig iron through roasting and oxygen partial pressures. The addition of CaO with 15 wt.% was found to reduce sulfur content up to 0.001 wt.%. The suitable temperature and reactive time for carbothermic reduction were $1600^{\circ}C$ and 30 minutes which shows the highest recovery rate of iron from the copper slag.

• Journal of Soil and Groundwater Environment
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• v.13 no.1
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• pp.24-31
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• 2008

Sulfate reducing bacteria (SRB) is universally distributed in the sediment, especially in marine environment. SRB reduce sulfate as electron acceptor to hydrogen sulfide in anaerobic condition. Hydrogen sulfide is reducing agent enhancing the reduction of the organic and inorganic compounds. With SRB, therefore, the degradability of organic contaminants is expected to be enhanced. Ferrous iron reduced from the ferric iron which is mainly present in sediment also renders chlorinated organic compounds to be reduced state. The objectives of this study are: 1) to investigate the reduction of TCE by hydrogen sulfide generated by tht growth of SRB, 2) to estimate the reduction of TCE by ferrous iron generated due to oxidation of hydrogen sulfide, and 3) to illuminate the interaction between SRB and ferrous iron. Mixed bacteria was cultivated from the sludge of the sewage treatment plant. Increasing hydrogen sulfide and decreasing sulfate confirmed the existence of SRB in mixed culture. Although hydrogen sulfide lonely could reduce TCE, the concentration of hydrogen sulfide produced by SRB was not sufficient to reduce TCE directly. With hematite as ferric iron, hydrogen sulfide produced by SRB was consumed to reduce ferric ion to ferrous ion and ferrous iron produced by hydrogen sulfide oxidation decreased the concentration of TCE. Tests with seawater confirmed that the activity of SRB was dependent on the carbon source concentration.