Effects of Oxide Coating and Selected Cations on Nitrate Reduction by Iron Metal

Huang, Yong; Zhang, Tian C.; Shea, Patrick J.; Comfort, Steve D.

doi:10.2134/jeq2003.1306

Cited by 126 publications

(65 citation statements)

References 31 publications

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“…[Burris et al 1995, Kim & Carraway 2000 Significant contaminant sorption in "Pollutant-ZVI-H 2 O"-Systems have been demonstrated and attributed to iron corrosion products or graphitic inclusions in ZVI materials. [Burris et al 1998, Lin & Lo 2005 Furthermore, the role the products of iron corrosion has been mostly investigated on synthetic materials [Farrell et al 1999, Huang et al 2003 or by pretreating ZVI materials by several procedures (e.g. acid-washing or H 2 reduction of ZVI).…”

Section: Effects Of Mno 2 Additionmentioning

confidence: 99%

“…[Gu et al 2002, Matheson et al 2002 The efficiency of ZVI for contaminant removal is presumed to highly depend on the properties of the metal surface because contaminant reduction reaction may mainly occur on the surface of iron [Keum & Li 2005, Matheson & Tratnyek 1994, Weber 1996 . Although it has been recognised that the formation of iron oxide or hydroxide over the surface may decrease the reactivity of ZVI materials, available information of the effects of oxide-films on the reductive capacity of ZVI materials results largely from well-mixed batch experiments [Huang et al 2003, Johnson et al 1998, Kim & Carraway 2000, Lin & Lo 2005, Ritter et al 2002, Weber et al 1996 . However, this experimental procedure (shaken or stirred batch experiments) may be inconsistent with groundwater environments (flow velocities 5-50 cm/day) where iron precipitates are continuously generated on ZVI surface, probably forming a reactive physical barrier to several contaminants [Devlin et al 1998, Devlin & Allin 2005, Mishra & Farrell 2005, Noubactep et al 2001 .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Investigating the Mechanism of Uranium Removal by Zerovalent Iron

Noubactep¹,

Meinrath

Merkel

2005

Environ. Chem.

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Environmental ContextGroundwater remediation is mostly a costly long-term process. In-situ remediation by permeable reactive barriers is a potential solution. For pollution by halogenated hydrocarbons, nitrate, and chromium, zerovalent iron (ZVI) has been found to induce a chemical reduction.ZVI remediation technology has been extended to metal pollution, where one of the major removal mechanisms seems to be co-precipitation with the products of iron corrosion. Due to difficulties of identifying reaction products in the matrix of corrosion products, investigation methods for characterising the contaminant removal with respect to interactions between contaminant and corrosion products need to be developed. AbstractZerovalent iron (ZVI) has been proposed as a reactive material in permeable in-situ walls for groundwater contaminated by metal pollutants. For such pollutants which interact with corrosion products, the determination of the actual mechanism of their removal is very important to predict the long-term stability of reactive walls. From a study of the effects of pyrite (FeS 2 ) and manganese nodules (MnO 2 ) on the uranium removal potential of a selected ZVI material, a test methodology (FeS 2 -MnO 2 -method) is suggested to follow the pathway of contaminant removal by ZVI materials. An interpretation of the removal potential of ZVI for uranium in presence of both additives corroborates coprecipitation with iron corrosion products as a major removal mechanism for uranium.

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Section: Effects Of Mno 2 Additionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigating the Mechanism of Uranium Removal by Zerovalent Iron

Noubactep¹,

Meinrath

Merkel

2005

Environ. Chem.

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“…Another technique for nitrate removal is the use of nano-scaled zero-valent irons (nZVI) (8). In recent years, nZVI has attracted the attention of many scientists (19). Due to high reduction capacity, high efficiency, abundance, cheapness, and its unique atomic, molecular, and chemical properties, nZVI has been used in the treatment of nitrate contaminated water (20,21).…”

Section: Introductionmentioning

confidence: 99%

Modeling Nitrate Removal by Nano-Scaled Zero-Valent Iron Using Response Surface Methodology

2014

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Background: Contamination of water resources with nitrate is a serious environmental problem in many regions of the world. In addition, this problem has been observed in some regions of Iran. As Nitrate is threatening for human health and environment, it must be decreased to standard levels in drinking water. Objectives: The purpose of this research was to model the nitrate removal from water by nano-scaled zero-valent iron (nZVI) using response surface methodology and to investigate the effects of the nZVI dose, nitrate concentration, contact time, and ionic strength on removal efficiency. Materials and Methods: Box-Behnken design was used. Response surface methodology was used for modeling nitrate removal. All experiments were conducted according to standard methods. Important assessed parameters included nZVI dose (0.5-2 g/L), nitrate concentration (50-150 mg/L), contact time (15-60 minutes), and ionic strength (1000-5000 μmho/cm). Results: Results indicated that there was a direct association between nitrate removal efficiency and time and nZVI dosage. Therefore, increasing of the contact time or nZVI dose would increase nitrate removal. On the other hand, the nitrate removal was decreased when ionic strength and initial concentration were increased. The analysis of variance revealed that the proposed regression model could be appropriately used to design experiments. The model correlation coefficient was 0.9992 and the adjusted value was 0.9982. Conclusions: Response surface methodology and Box-Behnken design were powerful statistical tools for navigating nitrate reduction process. The results showed that a high percentage of nitrate were reduced by nZVI and this method might be efficiently used for nitrate removal from water.

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“…Possible reasons included: (1) auto-reduction of atmospheric non-conductive corrosion products yielding electronic conductive magnetite [64,65]; (2) conversion of ferrous hydroxides on Fe 0 to electronic conductive magnetite via the Schikorr disproportionation reaction at pH > 6.0 [87]; and (3) the existence of fissures/defects in the oxide layers, which may initiate pitting corrosion, and allow thus the penetration of Cr VI to Fe 0 core [85,88]. However, it is certain that the effectiveness of Cr VI removal in Fe 0 /H 2 O systems cannot be ascribed to such processes since: (1) theoretically, for the direct reduction with Fe 0 to occur, the oxide scale should be electronic conductive; however, it was demonstrated that even electron transfer through electrically conductive magnetite occurs at a much lower rate than on the bare Fe 0 surface [87]; therefore, even after the coating of Fe 0 by magnetite, a reduction of the contaminants may become negligible [89]; and (2) pitting is usually initiated by the presence of important concentrations of aggressive anions (e.g., Cl − ), which are not usually found in natural aquatic environments. In addition, the longer diffusion path to the bottom of the pit restricts the transport of aqueous oxidants from the bulk solution [85].…”

Section: More Recent Laboratory-scale Reports (Post Elisabeth City Prb)mentioning

confidence: 99%

Progress in Understanding the Mechanism of CrVI Removal in Fe0-Based Filtration Systems

Gheju¹

2018

Water

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Hexavalent chromium (Cr VI ) compounds are used in a variety of industrial applications and, as a result, large quantities of Cr VI have been released into the environment due to inadequate precautionary measures or accidental releases. Cr VI is highly toxic to most living organisms and a known human carcinogen by inhalation route of exposure. Another major issue of concern about Cr VI compounds is their high mobility, which easily leads to contamination of surface waters, soil, and ground waters. In recent years, attention has been focused on the use of metallic iron (Fe 0 ) for the abatement of Cr VI polluted waters. Despite a great deal of research, the mechanisms behind the efficient aqueous Cr VI removal in the presence of Fe 0 (Fe 0 /H 2 O systems) remain deeply controversial. The introduction of the Fe 0 -based filtration technology, at the beginning of 1990s, was coupled with the broad consensus that direct reduction of Cr VI by Fe 0 was followed by co-precipitation of resulted cations (Cr III , Fe III ). This view is still the dominant removal mechanism (reductive-precipitation mechanism) within the Fe 0 remediation industry. An overview on the literature on the Cr geochemistry suggests that the reductive-precipitation theory should never have been adopted. Moreover, recent investigations recalling that a Fe 0 /H 2 O system is an ion-selective one in which electrostatic interactions are of primordial importance is generally overlooked. The present work critically reviews existing knowledge on the Fe 0 /Cr VI /H 2 O and Cr VI /H 2 O systems, and clearly demonstrates that direct reduction with Fe 0 followed by precipitation is not acceptable, under environmental relevant conditions, as the sole/main mechanism of Cr VI removal in the presence of Fe 0 .

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Effects of Oxide Coating and Selected Cations on Nitrate Reduction by Iron Metal

Cited by 126 publications

References 31 publications

Investigating the Mechanism of Uranium Removal by Zerovalent Iron

Investigating the Mechanism of Uranium Removal by Zerovalent Iron

Modeling Nitrate Removal by Nano-Scaled Zero-Valent Iron Using Response Surface Methodology

Progress in Understanding the Mechanism of CrVI Removal in Fe0-Based Filtration Systems

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