• 상하수도학회지
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• 제21권1호
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• pp.139-147
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• 2007

For environmental remediation of a contaminated groundwater plume, the use of zero-valent metal represents one of the latest innovative technologies. In this study, the effects of denitrification by zero-valent iron adsorbed in mesoporous silicas have been studied for groundwater contaminant degradation. The mesoporous silica was functionalized with 3-mercaptopropyltrimethoxysilane (MPTS) ligands and the zero-valent iron precipitated in the mesopore of granular silica was made by $FeCl_2$ and $NaBH_4$. Hydrogen was exchanged with $Fe^{2+}$ ions in the granular silicas. And then the ions were reduced by sodium borohydride in the mesoporous silicas. The surface area of the silica determined via the BET method ranged from 858 to $1275m^2/g$. The reductive reaction of nitrate-nitrogen indicated that the degradation of nitrate-nitrogen appeared to be pseudo first-order with the observed reaction rate constant kobs ($0.1619h^{-1}$) and to be directly proportional to the specific surface area. Therefore, the mesoporous silica with nano zero-valent iron proposed as a novel treatment strategy for contaminated groundwater was successfully implemented herein for the removal of nitrate-nitrogen.

• Nuclear Engineering and Technology
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• 제44권8호
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• pp.945-952
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• 2012

The sorption of selenium ions onto iron and iron compounds as a disposal container material and its corrosion products, and onto bentonite as a buffer material, was studied to understand the behaviors of selenium in a waste repository. Selenite was sorbed onto commercial magnetite very well in solutions at around pH 9, but silicate hindered their sorption onto both magnetite and ferrite. Unlike commercial magnetite and ferrite, flesh synthesized magnetite, green rust and iron greatly decreased selenium concentration even in a silicate solution. These results might be due to the formation of precipitates, or the sorption of selenide or selenite onto an iron surface at below Eh= -0.2 V. Red-colored Se(cr) was observed on the surface of a reaction bottle containing iron powder added into a selenite solution. Silicate influences on the sorption onto magnetite and iron for selenide are the same as those for selenite. Even though bentonite adsorbed a slight amount of selenite, the sorption cannot be ignored in the waste repository since a very large quantity of bentonite is used.

• Bulletin of the Korean Chemical Society
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• 제33권4호
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• pp.1290-1296
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• 2012

Fenton reaction and iron autoxidation have been debated for the major process in ROS mediated DNA cleavage. We compared both processes on iron oxidation, DNA cleavage, and cyclic voltammetric experiment at different pHs. Both oxidation reactions were preferred at basic pH condition, unlike DNA cleavage. This indicates that iron oxidation and the following steps probably occur separately. The ROS generated from autoxidation seems to be superoxide radical since sod exerted the best inhibition on DNA cleavage when $H_2O_2$ was absent. In comparison of cyclic voltammograms of $Fe^{2+}$ in NaCl solution and phosphate buffer, DNA addition to phosphate buffer induced significant change in the redox cycle of iron, indicating that iron may bind DNA as a complex with phosphate. Different pulse voltammogram in the presence of ctDNA suggest that iron ions are recyclable at acidic pH, whereas they may form an electrically stable complex with DNA at high pH condition.

• 한국미생물·생명공학회지
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• 제20권6호
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• pp.693-698
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• 1992

공장 폐수를 비롯한 중금속 오염 환경으로부터 효율적인 중금속 제거를 위해 생물학적 오염제거에 관한 연구가 많이 이루어지고 있다. 본 실험에서는 항생제 내성 유전자를 많이 가지고 있는 것으로 알려진 Serratia marcescens를 대상으로 이 균주가 중금속들에 대해 어떤 영향을 보이는지 조사하였다. 그 결과 lead, iron, magnesium, manganese 등의 처리군에서 24시간내에 1,000ppm 이상의 고농도 처리군에서 최소억제성장농도(MIC)를 나타냈으며, cadmium에서는 600ppm 처리군에서, 구리는 800ppm의 처리군에서 MIC를 보였으며, 아연 처리군에서는 800ppm에서 MIC를 나타냈다. 또한 48시간 배양에 따른 MIC 비교 결과, 중금속의 고농도 처리군에서 매우 긴 적응기를 갖는 것으로 확인하였다. 15가지의 항생체를 대상으로 저항성을 조사한 결과, ampicillin, tetracycline, cefamandole, cephalothin에서 저항성을 보엿으며 다른 S. marcescens 균주들에 비해 chloramphenicol에 대한 특이한 민감성을 보였다. 카드뮴과 납을 대상으로 중금속의 세포내 흡수를 조사한 결과 16.59%와 35.38%의 중금속이 세포내로 흡수되었음을 확인하였다.

• 대한환경공학회지
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• 제28권4호
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• pp.384-388
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• 2006

본 연구는 극성 및 독성물질에 대한 활성탄의 흡착력을 향상시키기 위하여, 활성탄을 산 처리 후 활성탄 50 g에 0.1 M $FeSO_4{\cdot}7H_2O,\;CuSO_4{\cdot}5H_2O,\;AgNO_3$ 용액을 300 mL 첨가하여 jar tester를 이용하여 60 rpm의 속도로 1시간 교반시켜 철, 은, 구리 이온을 첨착하였다. 금속 첨착과정으로 제조한 금속 첨착활성탄의 표면 성상 및 화학적 특성을 규명하기 위하여 비표면적, 세공용적 및 분포, 주사현미경 촬영, 흡착등온 등의 실험을 하였다. 산 처리 활성탄에 철, 구리, 은을 첨착할 경우 미세세공이 중간세공과 거대세공으로 전환되어 금속 첨착량이 약 1.3배 정도 증가하였고 금속 첨착활성탄내에서 미세세공에 의한 물리적 흡착과 침착된 금속 이온에 의한 화학적 흡착이 동시에 가능하였다.

• Nuclear Engineering and Technology
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• 제55권2호
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• pp.516-522
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• 2023

The co-precipitation process plays a key role in the decontamination of radionuclides from low and intermediate levels of liquid waste. For that reason, the removal of Cs ions from waste solution by the co-precipitation method was carried out. A simulated liquid waste (¹³³Cs) was prepared from a 0.1 M CsCl solution, while wastewater generated by washing steel ash served as a representative of radioactive cesium solution (¹³⁷Cs). By co-precipitation, potassium ferrocyanide was applied for the adsorption of Cs ions, while nickel nitrate and iron sulfate were selected for supporting the precipitation. The amount of residual Cs ions in the CsCl solution after precipitation and filtration was determined by ICP-OES, while the radioactivity of ¹³⁷Cs was measured using a gamma-ray spectrometer. After cesium removal, the amount of cesium appearing in both XRD and SEM-EDS was analyzed. The removal efficiency of ¹³³Cs was 60.21% and 51.86% for nickel nitrate and iron sulfate, respectively. For the ash-washing solution, the removal efficiency of ¹³⁷Cs was revealed to be more than 99.91% by both chemical agents. This implied that the co-precipitation process is an excellent strategy for the effective removal of radioactive cesium in waste solution treatment.

• Nuclear Engineering and Technology
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• 제55권7호
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• pp.2380-2387
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• 2023

Hyperspectral data and its ability to explore the minerals and their associated rocks have a remarkable application in mineral exploration and lithological characterization. The present study aims to explore the radiation shielding aspects of the iron ore in Kerala with the aid of the Hyperion hyperspectral dataset. The reflectance-spectra obtained from the laboratory conditions as well as from the image show various absorptions. The results from the spectra are validated with geochemical data and GPS points. The Monte Carlo simulation employed to evaluate the radiation shielding ability. Raising the oxygen ions caused a noteworthy decrease in the µ values of the studied rocks which is accompanied by an increase in Δ_0.5 and Δ_eq values. The Δ_0.5 and Δ_eq values increased by factors of approximately 77 % with raising the oxygen ions between 44.32 and 47.57 wt.%. The µ values varies with the oxygen concentrations, where the µ values decreased from 2.531 to 0.925 cm^-1 (at 0.059 MeV), from 0.381to 0.215 cm^-1 (at 0.662 MeV), and from 0.279 to 0.158 cm^-1 (at 1.25 MeV) with raising the oxygen ions from 44.32 to 47.43 wt.%.

• Nutrition Research and Practice
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• 제2권4호
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• pp.317-321
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• 2008

Macrophages play a key role in iron metabolism by recycling iron through erythrophagocytosis. Ferroportin-l (FPN1) is a transporter protein that is known to mediate iron export from macrophages. Since divalent metals often interact with iron metabolism, we examined if divalent metals could regulate the expression of FPN1 in macrophages. J774 macrophage cells were treated with copper, manganese, zinc, or cobalt at 10, 50, or $100\;{\mu}M$ for 16 to 24 h. Then, FPN1 mRNA and protein levels were determined by quantitative real-time PCR and Western blot analyses, respectively. In addition, effects of divalent metals on FPN1 promoter activity were examined by luciferase reporter assays. Results showed that copper significantly increased FPN1 mRNA levels in a dose-dependent manner. The copper-induced expression of FPN1 mRNA was associated with a corresponding increase in FPN1 protein levels. Also, copper directly stimulated the activity of FPN1 promoter-driven reporter construct. In contrast, manganese and zinc had no effect on the FPN1 gene expression in J774 cells. Interestingly, cobalt treatment in J774 cells decreased FPN1 protein levels without affecting FPN1 mRNA levels. In conclusion, our study results demonstrate that divalent metals differentially regulate FPN1 expression in macrophages and indicate a potential interaction of divalent metals with the FPN1-mediated iron export in macrophages.

• Bulletin of the Korean Chemical Society
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• 제23권1호
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• pp.119-122
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• 2002

Weakly coordinating anions show little affinity for binding to unfunctionalized iron(II) porphyrins. The electron-deficient 5, 10, 15, 20-tetrakis(pentafluorophenyl)porphinatoiron(II) compound is utilized in this study to demonstrate solution coordination by chloride, bromide and acetate ions. The binding strength of anions to the iron(II) porphyrin is reflected by a systematic change in pyrrole proton chemical shift in $^1H$ NMR spectra; the pyrrole resonance moves downfield when the ${\sigma}$-donor ability of anions is decreased.

• 통합자연과학논문집
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• 제1권2호
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• pp.76-78
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• 2008

A series of the long-chain iron(II) alkylsulfonate hydrates were synthesized via self-assembly of surfactant alkyl chains in aqueous medium. Reaction of iron(II) salts with n-alkylsulfonate yields lamellar $Fe(CnH2n+1SO3)2{\cdot}4H_2O$. These compounds show a layered structure, as determined by XRD, consisting of alternating organic alkylsulfonate layers and inorganic iron(II) hydrate layers, with interlayer distances of upto 3.2 nm. This lamellar structure may be attributed to the amphiphilic nature of the surfactants, mediating the coordination and H-bionding interactions, and the hydrophobic alkyl chains. An alkyl chain packing of present system are differ from those of similar Cu(II) series, which are attributed from the size of hydrated metal(II) ions.