• Title/Summary/Keyword: Zero Valent Iron

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Reduction of perchlorate in aqueous solution using zero valence iron stabilized with alginate bead (알지네이트 비드를 이용하여 안정화한 0가 철의 수용액 상에서의 과염소산 이온의 환원 분해 특성)

  • Joo, Tae-Kyeong;Lee, Jong-Chol;Paeng, Ki-Jung
    • 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.

Nitrate Reduction without Ammonium Release using Fe-loaded Zeolite

  • Lee Seunghak;Lee Kwanghun;Lee Sungsu;Park Junboum
    • Journal of Soil and Groundwater Environment
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    • v.10 no.1
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    • pp.1-5
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    • 2005
  • Nitrate reduction with zero valent iron $(Fe^0)$ has been extensively studied, but the proper treatment for ammonium byproduct has not been reported yet. In groundwater, however, ammonium is regarded as contaminant species, and particularly, its acceptable level is regulated to 0.5 mg-N/L. for drinking water. This study is focused on developing new material to reduce nitrate and properly remove ammonium by-products. A new material, Fe-loaded zeolite, is derived from zeolite modified by Fe(II) chloride followed by reduction with sodium borohydride. Batch experiments were performed without buffer at two different pH to evaluate the removal efficiency of Fe-loaded zeolite. After 80 hr reaction time, Fe loaded zeolite showed about $60\%$ nitrate removal at initial pH of 3.3 and $40\%$ at pH of 6 with no ammonium release. Although iron filing showed higher removal efficiency than Fe-loaded zeolite at each pH, it released a considerable amount of ammonium stoichiometrically equivalent to that of reduced nitrate. In terms of nitrogen species including $NO_3-N$ and $NH_4^+-N$, Fe-loaded zeolite removed about $60\%\;and\;40\%$ of nitrogen in residual solution at initial pH of 3.3 and 6, respectively, while the removal efficiency of iron filing was negligible.

Improvement of Salt Accumulated Soil and Crop Growth using Coal Ash (석탄회를 이용한 염류집적 토양 개선과 작물 생육 증진)

  • Lee, Jong Cheol;Oh, Se Jin;Kang, Min Woo;Kim, Young Hyun;Kim, Dong Jin;Lee, Sang Soo
    • Korean Journal of Environmental Agriculture
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    • v.40 no.2
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    • pp.83-91
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    • 2021
  • BACKGROUND: Cultivation area using agricultural plastic film facilities in Korea is rapidly increasing every year; however, it accelerates the salt accumulation in soils due to repeated cultivation and excessive use of chemical fertilizers. Coal ash contains various trace elements and has high potential to be used in agricultural purposes. This research was aimed to improve the quality of salts-accumulated soils and crop growth grown in the plastic film facilities using the soil amendment derived from coal ash and zero-valent iron powder. METHODS AND RESULTS: Soil amendment used in the study was manufactured using coal ash with iron powder and subjected to a typical upland soil for soil quality enhancement and two salts-accumulated soils for crop growth. After one month incubation of the salts-accumulated soils treated with the soil amendment, soil pH increased significantly and soil EC decreased by approximately 50%, compared to the control or the treatment without the soil amendment. Since the soil salts' concentration is proportional to EC, the subjected soil amendment can be proposed as an effective way to overcome soil salts accumulation in agricultural plastic film facilities. For crop growth, the length of roots and stems increased by approximately 10% and the dry weight also increased by a maximum of 75%, compared to the control. CONCLUSION: The soil amendment made from waste resources such as coal ash and zero-valent iron was found to not only be effective in improving salt-accumulated soils and crop yield but also be safe against harmful heavy metals.

Durability Extension of Fe(0) Column with Shewanella Algae BrY on TCE Treatment (Shewanella algae BrY를 이용한 영가철 칼럼의 TCE 처리 수명연장)

  • Chae, Heehun;Bae, Yeunook;Park, Jae-Woo
    • Journal of the Korean GEO-environmental Society
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    • v.8 no.2
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    • pp.41-48
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    • 2007
  • Zevo-valent iron (ZVI) has been widely used in permeable reactive barriers for reducing organic contaminants, such as trichloroethylene (TCE). The rapid reaction time, however, leads to decrease in reactivity and availability of ZVI. Shewanella algae BrY, a strain of dissimilatory iron reducing bacteria, can reduce the oxidized Fe (III) to Fe (II) and reduced Fe (II) can be reused to reduce the contaminant. The effect of Shewanella algae BrY on the reduction of the oxidized ZVI column and further TCE removal in the contaminated groundwater were studied at different flow rates and TCE input concentrations in this study. High input concentration of TCE and flow rate increase the amount of input contaminant and make to lower the effect of reduction by Shewanella algae BrY. Specially, the fast flow rate inhibits the direct contact and implantation on the surface of iron. The reduction of oxidized iron reactive barrier by Shewanella algae BrY can decrease the decreation of duration of PRBs by the precipitation of oxidized iron produced by dechlorination of TCE.

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Application of ZVI/TiO2 towards Clean-up of the Contaminated Soil with Polychlorinated Biphenyls (ZVI/TIO2를 이용한 폴리염화비페닐로 오염된 토양 정화)

  • Jae Wook Park;Yun Jin Jo;Dong-Keun Lee
    • Clean Technology
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    • v.29 no.2
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    • pp.118-125
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    • 2023
  • Once a site is contaminated with polychlorinated biphenyls (PCBs), serious environmental and human health risks are inevitable. Therefore, innovative but economical in situ remediation technologies must be immediately applied to the contaminated site. Recently, nanoscale zero-valent iron (nano-ZVI) particles have successfully been applied for the dechlorination of various chlorinated organic compounds like TCE, PCE and DDT, and they are considered to be environmentally safe due to the high abundance of iron in the earth's crust. Nano-ZVIs are much more reactive than granular ones, but tend to agglomerate due to their high surface energy and magnetic properties. In order to prevent them from being agglomerated toward larger particles, TiO2 was used as a support to immobilize the nano-ZVI particles as much as possible. 10wt% ZVI/TiO2 was prepared by adding NaBH4 slowly into an FeSO4/TiO2 aqueous slurry. In spite of their non-uniformity in size, the nano-ZVI particles were quite successfully dispersed onto the exterior surface of a non-porous TiO2 powder. The ZVI/TiO2 was then employed to degrade Aroclor 1242, a kind of PCBs standard, in spiked soil, and its reactivity towards the degradation of Aroclor 1242 was investigated. The fabricated ZVI/TiO2 degraded Aroclor 1242 in soil quite effectively, but the creation of remaining dechlorinated compounds, possibly high molecular weight hydrocarbons, in the soil was unavoidable.

Evaluation of Denitrification Reactivity by the Supported Nanoscale Zero-Valent Iron Prepared in Ethanol-Water Solution (이중용매에서 제조된 나노영가철을 이용한 질산성질소의 환원반응성 평가)

  • Park, Heesu;Park, Yong-Min;Oh, Soo-Kyeong;Lee, Seong-Jae;Choi, Yong-Su;Lee, Sang-Hyup
    • Korean Chemical Engineering Research
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    • v.46 no.5
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    • pp.1008-1012
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    • 2008
  • Nanoscale zero-valent iron(nZVI) is famous for its high reactivity originated from its high surface area and it has received considerable attentions as one of the latest innovative technologies for treating contaminated groundwater. Due to its fine powdery form, nZVI has limited filed applications. The efforts to overcome this shortcoming by immobilizing nZVI on a supporting material have been made. This study investigated the differences of resin-supported nZVI's characteristics by changing the preparation methods and evaluated its reactivity. The borohydride reduction of an iron salt was proceeded in ethanol/water solvent containing a dispersant and the synthesis was conducted in the presence of ion-exchange resin. The resulting material was compared to that prepared in a conventional way of using de-ionized water by measuring the phyrical and chemical characteristics. BET surface area and Fe content of nZVI-attached resin was increased from $31.63m^2/g$ and 18.19 mg Fe/g to $38.10m^2/g$ and 22.44 mg Fe/g, respectively, by switching the solution medium from water to ethanol/water with a dispersant. The reactivity of each material was tested using nitrate solution without pH control. The pseudo first-order constant of $0.462h^{-1}$ suggested the reactivity of resin-supported nZVI prepared in ethanol/water was increased 61 % compared to that of the conventional type of supported nZVI. The specific reaction rate constant based on surface area was also increased. The results suggest that this new supported nZVI can be used successfully in on-site remediation for contaminated groundwater.

A study of Immobilizing Heavy metals by pellets manufactured from Coal tailings and Iron oxide (선탄경석(選炭硬石)과 광산화물(鑛酸化物)로 제조(製造)한 담체(擔體)의 중금속(重金屬) 불용화(不溶化) 특성연구(特性硏究))

  • Lee, Gye-Seung;Song, Young-Jun
    • 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.

Removal of Nitrate in Groundwater by Bipolar ZVI Packed Bed Electrolytic Cell at Field Pilot (지하수중의 질산성질소 제거를 위한 영가철 충진 복극전해조의 현장적용에 관한 연구)

  • Na, So-Jeong;Jeong, Joo-Young;Kim, Han-Ki;Park, Joo-Yang
    • Journal of Korean Society of Water and Wastewater
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    • v.25 no.6
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    • pp.989-994
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    • 2011
  • Nitrate contamination of groundwater is a common problem throughout intensive agriculture areas (non-point source pollution). Current processes (e.g. ion exchange and membrane separation) for nitrate removal have various disadvantages. The objective of this study was to evaluate electrochemical method such as electroreduction using bipolar ZVI packed bed electrolytic cell to remove nitrate from groundwater at field pilot. In addition ammonia stripping tower continuously removed up to 77.0% of ammonia. Bipolar ZVI packed bed electrolytic cell also removed E.coli. In the field pilot experiment for groundwater in 'I' city (average nitrate 30~35 mg N/L, pH 6.4), maximum 99.9% removal of nitrate was achieved in the applied 600 V.

Mechanism of TCE Removal with Foundry Sands and Design of Permeable ]Reactive Barriers (주물사의 TCE 제거 메커니즘과 반응벽체에의 적용가능성)

  • ;Benson, Craig H
    • Journal of the Korean Geotechnical Society
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    • v.18 no.5
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    • pp.143-157
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    • 2002
  • Batch and column tests were conducted with common groundwater contaminants (i.e., trichloroethylene) to determine transport parameters and reactivity of the foundry sands. The reactivities of foundry sands for common groundwater contaminants are comparable to or slightly higher than those for Peerless iron a common medium used in permeable reactive barriers. In addition, the TOC and clay in foundry sands can significantly retard the movement of target contaminants, which may result in lower effluent concentrations of contaminants due to biodegradation. In general, permeable reactive barriers with the thickness of 1m can be constructed with many foundry sands to treat typical groundwater comtaminants provided the zero-valent iron content in the foundry sand is higher than 1%.

Improving the Reactivity and Harmlessness of Recalcitrant Contaminants by Reduction-oxidation-linked Process (환원-산화 연계처리를 통한 니트로벤젠의 반응성 향상 및 무해화 연구)

  • Kwon, Hee-Won;Hwang, Inseong;Kim, Young-Hun
    • Journal of Environmental Science International
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    • v.29 no.12
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    • pp.1205-1211
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    • 2020
  • In this study, the applicability of reduction-oxidation-linked treatment was evaluated for nitrobenzene and a by-product by analyzing the reaction kinetics. Nitrobenzene showed very low reactivity to persulfate that was activated using various methods. Nitrobenzene effectively reacted through the reduction process using Zero-Valent Iron (ZVI). However, aniline, a toxic substance, was produced as a by-product. Reduction-oxidation-linked treatment is a method that can allow the oxidative degradation of aniline after reducing nitrobenzene to aniline. The experimental results show improved reactivity and complete decomposition of the by-product. Improved reactivity and decomposition of the by-product were observed even under conditions in which the reduction-oxidation reaction was induced simultaneously. No activator was injected for persulfate activation in the process of reducing oxidant linkage, and the activation reaction was induced by ferrous iron eluted from the ZVI. This indicates that this method can be implemented relatively simply.