Transformation of chlorinated organic compounds by iron and manganese powders in buffered water and in landfill leachate

Schreier, Cindy G.; Reinhard, Martin

doi:10.1016/0045-6535(94)90320-4

Cited by 108 publications

(95 citation statements)

References 11 publications

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“…Beside these abiotic mechanisms, contaminants can be reduced at the site of their adsorption (more or less far from the metal surface) by indigenous micro organisms [105]. A convincing argument for contaminant sorption/ co-precipitation on to/with corrosion products (oxide film) as initial removal mechanism is the manifold observed lag time between the date of Fe 0 materials addition and the beginning of quantitative contaminant removal [55,[106][107][108]. Elusive arguments have been proposed to rationalize this experimental evidence.…”

Section: Discussionmentioning

confidence: 99%

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

Noubactep¹

2008

Environmental Technology

344

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: Discussionmentioning

confidence: 99%

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

Noubactep¹

2008

Environmental Technology

344

308

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“…In many cases, aqueous contaminant removal has been reported to occur after a lag time [18,[31][32][33]. Such lag time is often seen in biological systems if the initial population of bacteria is small, or if synthesis of the appropriate enzymes must be induced [33].…”

Section: Experimental Observationsmentioning

confidence: 99%

“…Such lag time is often seen in biological systems if the initial population of bacteria is small, or if synthesis of the appropriate enzymes must be induced [33]. In Fe 0 -H 2 O systems the observed lag time can be regarded as the time necessary for the generation of enough corrosion products for contaminant co-precipitation [18][19][20].…”

Section: Experimental Observationsmentioning

confidence: 99%

“…According to the MTW concept all these reducible species should have been reduced to Se IV , Cr III and U IV respectively. Qui et al [33] reported that partially reduced Se IV and Cr III are adsorbed on the Fe 0 surface, while uranium is deposited without reduction (U VI ). All species were quantitatively removed from the aqueous solution.…”

Section: Experimental Observationsmentioning

confidence: 99%

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Processes of Contaminant Removal in “Fe0-H2O” Systems Revisited: The Importance of Co-Precipitation

Noubactep¹

2008

TOENVIRSJ

110

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Abstract:The mechanism of aqueous contaminant removal by elemental iron (Fe 0 ) materials (e.g., in Fe 0 -H 2 O systems) has been largely discussed in the "iron technology" literature. Two major removal mechanisms are usually discussed: (i) contaminant adsorption onto Fe 0 oxidation products, and (ii) contaminant reduction by Fe 0 , Fe II or H/H 2 . However, a closer inspection of the chemistry of the Fe 0 -H 2 O system reveals that co-precipitation could be the primary removal mechanism. The plausibility of contaminant co-precipitation with iron corrosion products as independent contaminant removal mechanism is discussed here. It shows that the current concept does not take into account that the corrosion product generation is a dynamic process in the course of which contaminants are entrapped in the matrix of iron hydroxides. It is recalled that contaminant co-precipitation with iron hydroxides/oxides is an unspecific removal mechanism. Contaminant co-precipitation as primary removal mechanism is compatible with subsequent reduction and explains why redoxinsensitive species are quantitatively removed. Adsorption and co-precipitation precede reduction and abiotic reduction, when it takes place, occurs independently by a direct (electrons from Fe 0 ) or an indirect (electrons from Fe II /H 2 ) mechanism.

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“…It strongly masks the real mechanisms of contaminant removal as that is a complex interplay between Fe 0 particles, Fe II released into solution and Fe II /Fe III precipitation [89][90][91][92][93][94][95][96]. In particular, the transformation of Fe 0 to Fe oxides goes through colloids and hydroxides.…”

Section: Contaminant Removal In Fe 0 /H 2 O Systemsmentioning

confidence: 99%

Predicting the Hydraulic Conductivity of Metallic Iron Filters: Modeling Gone Astray

Noubactep

2016

Water

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Abstract:Since its introduction about 25 years ago, metallic iron (Fe 0 ) has shown its potential as the key component of reactive filtration systems for contaminant removal in polluted waters. Technical applications of such systems can be enhanced by numerical simulation of a filter design to improve, e.g., the service time or the minimum permeability of a prospected system to warrant the required output water quality. This communication discusses the relevant input quantities into such a simulation model, illustrates the possible simplifications and identifies the lack of relevant thermodynamic and kinetic data. As a result, necessary steps are outlined that may improve the numerical simulation and, consequently, the technical design of Fe 0 filters. Following a general overview on the key reactions in a Fe 0 system, the importance of iron corrosion kinetics is illustrated. Iron corrosion kinetics, expressed as a rate constant k iron , determines both the removal rate of contaminants and the average permeability loss of the filter system. While the relevance of a reasonable estimate of k iron is thus obvious, information is scarce. As a conclusion, systematic experiments for the determination of k iron values are suggested to improve the database of this key input parameter to Fe 0 filters.

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Transformation of chlorinated organic compounds by iron and manganese powders in buffered water and in landfill leachate

Cited by 108 publications

References 11 publications

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

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

Processes of Contaminant Removal in “Fe0-H2O” Systems Revisited: The Importance of Co-Precipitation

Predicting the Hydraulic Conductivity of Metallic Iron Filters: Modeling Gone Astray

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Transformation of chlorinated organic compounds by iron and manganese powders in buffered water and in landfill leachate

Cited by 108 publications

References 11 publications

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

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

Processes of Contaminant Removal in “Fe0-H2O” Systems Revisited: The Importance of Co-Precipitation

Predicting the Hydraulic Conductivity of Metallic Iron Filters: Modeling Gone Astray

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

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