• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.1B
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• pp.85-91
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• 2012

Permeable Reactive Barriers (PRBs) using zero valent iron (ZVI, $Fe^0$) is a promising technology for in-situ remediation of trichloroethylene (TCE) forming dense non aqueous phase liquid (DNAPL). The objective of this study is to develop an enhanced treatment method of trichloroethylene-contaminated groundwater using ZVI packed bed with direct current (D.C.). A column experiment was performed to investigate degradation efficiency of TCE that was performed in three different combination of control (only sand), ZVI column (ZVI:sand, packing ratio 1:2(v/v)) and bipolar column (ZVI:sand=1:2(v/v) with electric current) in the test columns. As the results of this study, the degradation efficiency of TCE was improved with simultaneous application of both bipolar column compared to that used ZVI column. Because ZVI particles are isolated and individual particles act like small electrodes. In this experiment, it was indicated a basic material for application of bipolar packed bed as electro-PRBs that was effective degradation of TCE.

• Journal of the Mineralogical Society of Korea
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• v.30 no.4
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• pp.173-178
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• 2017

In this study, the effect of sintering temperature and zero valent iron (ZVI) content on the physical properties of functional ceramic filter(alumina based materials) such as strength and porosity were investigated. The fabrication process of the functional ceramic filter were performed under various sintering temperature ($1150^{\circ}C$, $1250^{\circ}C$) and ZVI content (10, 20, 30, 50%) conditions. With increasing the sintering temperature and ZVI content, strength was increased but porosity was decreased. The physical properties for functional ceramic filter showed that the strength and porosity were obtained under ZVI content (50%) and sintering temperature ($1250^{\circ}C$) of 99.01 MPa and 34.5%, respectively.

• 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 $FeAsO_4{\cdot}2H_2O$.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.395-398
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• 2003

Geosynthetic Clay Liners(GCLs) have been widely used as hydraulic barrier in landfills and remediation projects of contaminated sites. The aim of this research is to modify GCLs for effective removal of contaminants. We perform the free swell test, hydraulic conductivity test, and contaminants (TCE, hexavalent chromium, and nitrate) removal test on the bentonite-ZVI mixture with various ZVI content. As the ZVI content increased, contaminants removal efficiencies and swell volume increased, and hydraulic conductivity decreased.

• Journal of Soil and Groundwater Environment
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• v.11 no.4
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• pp.33-40
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• 2006

Residual pesticides discharged from diffuse sources at agricultural area in association with suspended solid will be settled at downstream, and may degrade surface water quality. This research studied dechlorination kinetic of atrazine, one of triazine-category herbicide, using zero-valent iron (ZVI) in sediment. It can be observed from the experiments that buffer capacity of sediment helped pH maintained beutral, resulted in continuous dechlorination. Sediments were spiked with atrazine at 10, 30, and 50 mg atrazine/L of total sediment for batch experiments. Dechlorination constants were $1.38x10^{-1}/d$ for the initial concentration of 10 mg/L, $1.29x10^{-l}/d$ for 30 mg/L, and $7.43x10^{-2}/d$ for 50 mg/L while dechlorination constants of initial concentration of 50 mg/L without ZVI adding were estimated as $3.05x10^{-2}/d. Half lifes atrazine by ZVI were estimated as 5.03 d fur 10 mg/L, 5.38 d for 30 mg/L, and 9.33 d for 50 mg/L, respectively.

• Journal of the Mineralogical Society of Korea
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• v.16 no.1
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• pp.107-123
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• 2003

The objective of this study was to investigate mineral precipitates, which derived from the zero valent iron (ZVI) corrosion during TCE dechlorination and to find the controlling factors in mineral precipitates. A series of column experiemnts were conducted to evaluate the location of ZVI and the effects of electrode arrangements in electro-enhanced permeable reactive barrier (E2PRB) systems. Based on mineralogical study, ZVI samples near the influent port had more lepidocrocite, ferrihydrite or Fe (oxy)hydroxide, and (phospho)siderite while backward samples had more akaganeite, magnetite/maghemite, and intermediate green rust (GR) I and GR II. A suite of mineral distribution was preferabley related to the dissolved oxygen and the increased pH. Controlling factors of mineral precipitates in an E2PRB system were found to be (1) pH, (2) dissolved oxygen, (3) the types of Fe intermediates, and (4) anionic species to form complex strongly.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.67-70
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• 2002

Remediation of groundwater contaminated with chlorinated organics, nitro aromatics, and heavy metals using zero valent iron (ZVI) filings has paid considerable attention in recent years. When the contaminants of high concentration leaked abundantly in subsurface environment, permeable reactive barrier technology using iron filing is taken a long time for the remediation of contaminated groundwater, The problem of contaminant shock is able to be solved using surfactant (hexadecyltrimethylammonium, HDTMA) modified bentonite (SMB) as immobilizing material. Therefore, the purpose of this research was to develop the combined remediation technology using conventional permeable reactive and immobilizing barrier for the enhanced decontamination of chlorinated compounds. Four column experiments were conducted to assess the performance of the mixed reactive materials with Ottawa sand, iron filing, and HDTMA-bentonite for trichloroethylene (TCE) removal under controlled groundwater flow conditions. TCE reduction rates with sand/iron filing/HDTMA-bentonite were highest among four column due to dechlorination of TCE by iron filing and sorption of TCE by SMB.

• Journal of Soil and Groundwater Environment
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• v.14 no.6
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• pp.101-107
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• 2009

Carboxymethyl cellulose (CMC) as stabilizer is expected to facilitate in-situ delivery of zero-valent iron (ZVI) nanoparticles in a contaminated aquifer because it increases dispersity of ZVI nanoparticles. This work investigated the transport of CMC-stabilized ZVI nanoparticles (CMC-Fe) using column breakthrough experiments. The ZVI nanoparticles (100 mg/L Fe) were transportable through sand porous media. In contrast, non-stabilized ZVI nanoparticles rapidly agglomerate in solution and are stopped in sand porous media. At pH 7 of solution approximately 80% CMC-Fe were eluted. When the pH of solution is below 5, 100% CMC-Fe were eluted. These results suggest that the mobility of CMCFe was increased as pH decreases. In the mobility test under different ionic strengths using $Na^+$ and $Ca^{2+}$ ions, there was no signigficant difference in the mobility of CMC-Fe. Also, in the experiments of effect of clay and natural organic mater (NOM) on the mobility of ZVI, there was no significant difference in the mobility of CMC-Fe not only between 1 and 5% clay, but 100 and 1000 mg/L NOM. The results from this work suggests that the CMC-Fe nanoparticles could be easily delivered into the subsurface over a broad range of ionic strength, clay and NOM.

• 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.

• 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.