Zero-valent iron for the in situ remediation of selected metals in groundwater

Cantrell, Kirk J.; Kaplan, Daniel I.; Wietsma, Thomas

doi:10.1016/0304-3894(95)00016-n

Cited by 325 publications

(191 citation statements)

References 6 publications

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“…Different classes of organic and inorganic compounds have been successfully removed from the aqueous phase in the presence of Fe 0 materials [1,[6][7][8][9][10][11][12][13][14][15]. The earliest detailed surveys involving contaminant removal by Fe 0 materials in laboratory batch systems raised speculation that the decontamination occurs through a reduction reaction at the surface of the metal [16][17][18][19][20]. In the meantime several other reductants (secondary reductants) have been identified in the system Fe 0 -H 2 O, including green rust, structural Fe II and atomic or molecular hydrogen [21][22][23].…”

Section: Introductionmentioning

confidence: 99%

A CRITICAL REVIEW ON THE PROCESS OF CONTAMINANT REMOVAL IN FE⁰–H₂O SYSTEMS

Noubactep¹

2008

Environmental Technology

343

308

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A central aspect of the contaminant removal by elemental iron materials (Fe 0 or Fe 0 materials) is that reduction reactions are mediated by the iron surface (direct reduction). This premise was introduced by the pioneers of the reactive wall technology and is widely accepted by the scientific community. In the meantime enough evidence has been provided to suggest that contaminant reduction through primary corrosion products (secondary reductants) does indeed occur (indirect reduction). It was shown for decades that iron corrosion in the pH range of natural waters (4-9) inevitably yields an obstructive oxide film of corrosion products at the metal surface (oxide film). Therefore, contaminant adsorption on to corrosion products and contaminant co-precipitation with corrosion products inevitably occurs. For adsorbed and coprecipitated contaminants to be directly reduced the oxide film should be electronic conductive. This study argues through a literature review a series of points which ultimately lead to the conclusion that, if any quantitative contaminant reduction occurs in the presence of Fe 0 materials, it takes place within the matrix of corrosion products and is not necessarily a direct reduction. It is concluded that Fe 0 materials act both as source of corrosion products for contaminant adsorption/coprecipitation and as a generator of Fe II and H 2 (H) for possible catalytic contaminant reduction.

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Section: Introductionmentioning

confidence: 99%

A CRITICAL REVIEW ON THE PROCESS OF CONTAMINANT REMOVAL IN FE⁰–H₂O SYSTEMS

Noubactep¹

2008

Environmental Technology

343

308

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“…22,23 Much work has already been done to investigate the use of ZVI and nZVI to reduce Cr(VI) over the common environmental pH range of mildly acidic to moderately alkaline conditions. [22][23][24][25][26][27] In acidic conditions the reaction is relatively fast, but the rate of reaction is slower in neutral and mildly alkaline conditions. 28 The primary objective of this study is to extend understanding of the reaction between ZVI and Cr(VI) to alkaline conditions characteristic of COPR leachate.…”

Section: Introductionmentioning

confidence: 99%

“…25 Aqueous chromate is a widely used and very effective inhibitor of iron corrosion because the mixture of ferric and chromic oxides and 7 hydroxides produced are deposited at the reaction site. 37 Such inhibition is responsible for slower reaction rates between ZVI and Cr(VI) with increasing concentrations of Cr(VI) in solution.…”

mentioning

confidence: 99%

Chromate Reduction in Highly Alkaline Groundwater by Zerovalent Iron: Implications for Its Use in a Permeable Reactive Barrier

Fuller

Stewart

Burke

2013

Ind. Eng. Chem. Res.

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It is not currently known if the widely used reaction of zero valent iron (ZVI) and Cr(VI) can be used in a permeable reactive barrier (PRB) to immobilise Cr leaching from hyper alkaline chromite ore processing residue (COPR). This study compares Cr(VI) removal from COPR leachate and chromate solution by ZVI at high pH. Cr(VI) removal occurs more rapidly from the chromate solution than from COPR leachate. The reaction is first order with respect to both [Cr(VI)] and the iron surface area, but iron surface reactivity is lost to the reaction.Buffering pH downwards produces little change in the removal rate or the specific capacity of iron until acidic conditions are reached. SEM and XPS analysis confirm that reaction products accumulate on the iron surface in both liquors, but that other surface precipitates also form in COPR leachate. Leachate from highly alkaline COPR contains Ca, Si and Al that precipitate on the iron surface and significantly reduce the specific capacity of iron to reduce Cr(VI). This study suggests that although Cr (VI) reduction by ZVI will occur at hyper alkaline pH, other solutes present in COPR leachate will limit the design life of a PRB. 4

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“…Thus the overall reaction is: [16][17][18][19][20][21][22][23][24][25][26][27]. Although Fe 0 has been applied extensively for remediation of several pollutants, the major drawbacks are slow reaction rates, rapid passivation of the metal and requirement for strict anaerobic conditions.…”

Section: Introductionmentioning

confidence: 99%