• Title, Summary, Keyword: 영가철

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Simultaneous Removal of Nitrate and Trichloroethylene by Zero Valent Iron and Peat (영가철과 피트를 이용한 질산성질소와 트리클로로에틸렌의 제거)

  • Min, Jee-Eun;Kim, Mee-Jeong;Park, Jae-Woo
    • Journal of Korean Society of Environmental Engineers
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    • v.28 no.10
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    • pp.1074-1081
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    • 2006
  • As common pollutants in surface and groundwater, nitrate nitrogen($NO_3-N$) and trichloroethylene(TCE) can be chemically and biologically reduced by zero valent iron(ZVI) and peat soil. In batch microcosm experiments, chemical reduction of TCE and nitrate was supported by hydrogen from ZVI. For biological degradation of TCE and denitrification peat soil was introduced. ZVI reduced TCE, while peat provided TCE sorption site and microbes performing biological degradation. Nitrate reduction was also achieved by hydrogen from ZVI. In addition, indirect evidence of denitrification was observed. More reduction of TCE and nitrate was achieved by ZVI+peat treatment however nitrated reduction was hindered in the presence of TCE in the system due to the competition for hydrogen. TCE reduction mechanism was more dependent on ZVI, while nitrate was peat-dependent. Hydrogen and methane concentration showed that peat had various anaerobic denitryfing and halorespiring bacteria.

Optimization of Synthesis Condition for Nanoscale Zero Valent Iron Immobilization on Granular Activated Carbon (영가철이 고정된 입상활성탄 제조를 위한 최적 합성조건 도출)

  • Hwang, Yuhoon;Mines, Paul D.;Lee, Wontae;Andersen, Henrik R.
    • Journal of Korean Society of Environmental Engineers
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    • v.38 no.9
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    • pp.521-527
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    • 2016
  • Nanoscale zero valent iron (nZVI) has been intensively studied for the treatment of a plethora of pollutants through reductive reaction, however, the nano size should be of concern when nZVI is considered for water treatment, due to difficulties in recovery. The loss of nZVI causes not only economical loss, but also potential risk to human health and environment. Thus, the immobilization onto coarse or structured support is essential. In this study, two representative processes for nZVI immobilization on granular activated carbon (GAC) were evaluated, and optimized conditions for synthesizing Fe/GAC composite were suggested. Both total iron content and $Fe_0$ content can be significantly affected by preparation processes, therefore, it was important to avoid oxidation during preparation to achieve higher reduction capacity. Synthesis conditions such as reduction time and existence of intermediate drying step were investigated to improve $Fe_0$ content of Fe/GAC composites. The optimal condition was two hours of $NaBH_4$ reduction without intermediate drying process. The prepared Fe/GAC composite showed synergistic effect of the adsorption capability of the GAC and the degradation capability of the nZVI, which make this composite a very effective material for environmental remediation.

Reduction Efficiency of Cr(VI) in Aqueous Solution by Different Sources of Zero-Valent Irons (수용액 중 영가 철(Zero-Valent Iron)의 특성에 따른 Cr(VI)의 환원 효율 비교)

  • Yang, Jae-E.;Kim, Jong-Sung;Ok, Yong-Sik;Yoo, Kyung-Yoal
    • Korean Journal of Environmental Agriculture
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    • v.24 no.3
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    • pp.203-209
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    • 2005
  • Objective of this research was to assess the effectiveness of the different sources of the zero-valent irons (ZVIs) on the reduction of the toxic Cr(VI) to the nonhazardous Cr(III) in an aqueous solution. The physical and chemical properties of the six ZVIs were determined. Particle size and specific surface area of the ZVIs were in the ranges of $85.55{\sim}196.46{\mu}m\;and\;0.055{\sim}0.091m^2/g$, respectively. Most of the ZVIs contained Fe greater than 98% except for J (93%) and PU (88%). Reduction efficiencies of the ZVI for Cr(VI) reduction were varied with kinds of ZVIs. The J and PU ZVIs reduced 100% and 98% of Cr(VI) in the aqueous solution, respectively, within 3 hrs of reaction. However, PA, F, Sand J1 reduced 74, 65, 29 and 11% of Cr(VI), respectively, after 48 hrs. The pH of the reacting solution was rapidly increased from 3 to $4.34{\sim}9.04$ within 3 hrs. The oxidation-reduction potential (Eh) of the reacting solution was dropped from 600 to 319 mV within 3 hrs following addition of ZVIs to the Cr(VI) contaminated water. The capability of ZVIs for Cr(VI) reduction was the orders of PU > J > PA > F > S > J1, which coincided with the capacities to increase the pH and decrease the redox potentials. Results suggested that the reduction of Cr(VI) to Cr(III) was derived from the oxidation of the ZVI in the aqueous solution.

Discoloration of Azo-Dyes Using Zerovalent Iron (영가철을 이용한 아조계 염료의 탈색)

  • Jeong, Yong-Sik;Lim, Woo-Taik;Kim, Jong-Hyun;Oh, Hyung-Suk;Kim, Young-Hun
    • Journal of Korean Society of Environmental Engineers
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    • v.30 no.12
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    • pp.1262-1267
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    • 2008
  • Reductive discolorization studies were conducted. Azo-dyes usually have biological toxicity and it is known that the dyes are hardly removed by biological treatments. One of the simplest way to remove the color is to break the azo-bond and it is possible to break the bond with zero-valent metals. Three types of azo-dyes (Cibacron Briliant Yellow 3G-P (CBY3G-P), Benzopurpurin 4b (B-4B), Chicago sky blue 6b (CSB6B)) were tested. All tested azo-dyes were highly pH dependent and lower pH was preferred. The reaction mechanism was reductive cleavage and amines were expected as products. The dissolved iron ions from zero-valent iron can also remove the color through coagulation and precipitation and a set of experiments were conducted to evaluate the contribution by the dissolved iron. The results indicated that the contribution were also dependent on the type of dyes. This study showed that the reductive cleavage using zero-valent iron could be an alternative for the azo-dye waste water.

Characterization of Behavior of Colloidal Zero-Valent Iron and Magnetite in Aqueous Environment (나노크기의 교질상 영가철 및 자철석에 대한 수용상의 거동특성)

  • Lee, Woo Chun;Kim, Soon-Oh;Kim, Young-Ho
    • Journal of the Mineralogical Society of Korea
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    • v.28 no.2
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    • pp.95-108
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    • 2015
  • Nano-sized iron colloids are formed as acid mine drainage is exposed to surface environments and is introduced into surrounding water bodies. These iron nanomaterials invoke aesthetic contamination as well as adverse effects on aqueous ecosystems. In order to control them, the characteristics of their behaviour should be understood first, but the cumulative research outputs up to now are much less than the expected. Using zero-valent iron (ZVI) and magnetite, this study aims to investigate the behaviour of iron nanomaterials according to the change in the composition and pH of background electrolyte and the concentration of natural organic matter (NOM). The size and surface zeta potential of iron nanomaterials were measured using dynamic light scattering. Characteristic behaviour, such as aggregation and dispersion was compared each other based on the DLVO (Derjaguin, Landau, Verwey, and Overbeek) theory. Whereas iron nanomaterials showed a strong tendency of aggregation at the pH near point of zero charge (PZC) due to electrostatic attraction between particles, their dispersions became dominant at the pH which was higher or lower than PZC. In addition, the behaviour of iron nanomaterials was likely to be more significantly influenced by cations than anions in the electrolyte solutions. Particularly, it was observed that divalent cation influenced more effectively than monovalent cation in electrostatic attraction and repulsion between particles. It was also confirmed that the NOM enhanced the dispersion nanomaterials with increasing the negative charge of nanomaterials by coating on their surface. Under identical conditions, ZVI aggregated more easily than magnetite, and which would be attributed to the lower stability and larger reactivity of ZVI.

Sorption of Dissolved Inorganic Phosphorus to Zero Valent Iron and Black Shale as Reactive Materials (반응매질로서의 영가철 및 블랙셰일에 용존무기 인산염 흡착)

  • Min, Jee-Eun;Park, In-Sun;Ko, Seok-Oh;Shin, Won-Sik;Park, Jae-Woo
    • Journal of Korean Society of Environmental Engineers
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    • v.30 no.9
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    • pp.907-912
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    • 2008
  • In order to reduce the availability of dissolved inorganic phosphorus in surface water, lakes, and estuaries, black shale and zero valent iron can be used as reacitve materials. Sorption of phosphate to sampled sediment, black shale, and zero valent iron was quantitatively evaluated in this research. Effect of coexistence of calcium was also tested, since coexisting ions can enhance the precipitation of phosphate. An empirical kinetic model with fast sorption(k$_t$), slow sorption(k$_s$), and precipitation(k$_p$) was well fitted to experiment data from this research. Langmuir and Freundlich sorption isotherms were also used to evaluated phosphate maximum sorption capacity. Calcium ions at 0, 1 and 5 mM affected the precipitation kinetic coefficient in empirical kinetic model but did not have impact on the maximum sorbed concentration.

Mechanism and Adsorption Capacity of Arsenic in Water by Zero-Valent Iron (수용액 중 영가 철의 비소흡착 및 반응기작 구명)

  • Yoo, Kyung-Yoal;Ok, Yong-Sik;Yang, Jae E.
    • Korean Journal of Soil Science and Fertilizer
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    • v.39 no.3
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    • pp.157-162
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    • 2006
  • Objective of this research was to evaluate optimal conditions of arsenic adsorption in water by zero-valent iron (ZVI). Batch experiment showed that adsorption of arsenic by ZVI followed a Langmuir isotherm model. The masses of As(V) adsorbed onto ZVI were increased as decreasing pH of the reacting solution (pH 3: 2.05, pH 5: 1.82, pH 7: 1.24, pH 9: 1.03 mg As/g $Fe^0$) and as increasing the temperature ($15^{\circ}C$ : 1.59, $25^{\circ}C$ : 1.81, 35 : $1.93^{\circ}C$ mg As/g $Fe^0$). The SEM and EDS (energy dispersive X-ray spectrometer) analysis of morphology and structure of ZVI before and after reacting with arsenic in water revealed that a relatively smooth and large surface of ZVI was transformed into a coarse and small surface particle after the reaction. The EDS spectra on the chemical composition of ZVI demonstrated that arsenic was incorporated into ZVI by adsorption mechanism. The XRD analysis also identified that the only peak for $Fe^0$ in the ZVI before the reaction and confirmed that $Fe^0$ was transformed into $Fe_2O_3$ and FeOOH, and As into $FeAsO_4{\cdot}2H_2O$.

Modification of Indophenol Reaction for Quantification of Reduction Activity of Nanoscale Zero Valent Iron (나노 영가철 환원 반응성의 정량 분석을 위한 수정된 인도페놀법 적용)

  • Hwang, Yuhoon;Lee, Wontae;Andersen, Henrik R.
    • Journal of Korean Society of Environmental Engineers
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    • v.38 no.12
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    • pp.667-675
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    • 2016
  • Nanoscale zero-valent iron (nZVI) has been effectively applied for environmental remediation due to its ability to reduce various toxic compounds. However, quantification of nZVI reactivity has not yet been standardized. Here, we adapted colorimetric assays for determining reductive activity of nZVIs. A modified indophenol method was suggested to determine reducing activity of nZVI. The method was originally developed to determine aqueous ammonia concentration, but it was further modified to quantify phenol and aniline. The assay focused on analysis of reduction products rather than its mother compounds, which gave more accurate quantification of reductive activity. The suggested color assay showed superior selectivity toward reduction products, phenol or aniline, in the presence of mother compounds, 4-chlorophenol or nitrobenzene. Reaction conditions, such as reagent concentration and reaction time, were optimized to maximize sensitivity. Additionally, pretreatment step using $Na_2CO_3$ was suggested to eliminate the interference of residual iron ions. Monometallic nZVI and bimetallic Ni/Fe were investigated with the reaction. The substrates showed graduated reactivity, and thus, reduction potency and kinetics of different materials and reaction mechanism was distinguished. The colorimetric assay based on modified indophenol reaction can be promises to be a useful and simple tool in various nZVI related research topics.

Screening of Zero-Valent Metal for the Removal of High Concentration PCE and 1,1,1 TCA (고농도 PCE 및 1,1,1 TCA 제거를 위한 영가금속 선정)

  • Kwon, Soo-Youl;Kim, Young
    • Journal of Wetlands Research
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    • v.12 no.1
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    • pp.23-31
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    • 2010
  • Chlorinated aliphatic hydrocarbons (CAHs) such as tetrachloroethylene (PCE), 1,1,1-trichloroethane (1,1,1-TCA) are the contaminants most frequently found in soil and groundwater. They have a potential to be toxic to and persistent in environment. This study is focused on selection of zero-valent metal and ores for the removal of high concentration PCE or 1,1,1-TCA and mixture of two compound. For the screening of suitable metals, we measured dechlorination rate, removal capacities and economics by using batch reactor test. This results suggest that removal rate and dechlorination of high quality iron and zinc are higher than slag and nature ores like zinc and manganese. Among nature ores, zinc ores(64% purity) have highest removal capacities. And in economics zinc ores is 10 times better than high quality metal tested. We conclude zinc ore is most suitable metal for the removal of PCE or 1,1,1-TCA.