Reduction of Hexavalent Chromium in Aqueous Medium with Zerovalent Iron

Dutta, R. K.; Mohammad, Sk. Saker; Chakrabarti, Sudipta; Chaudhuri, Basab; Bhattacharjee, Sekhar; Dutta, Binay K.

doi:10.2175/106143009x426013

Cited by 20 publications

(18 citation statements)

References 33 publications

(37 reference statements)

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“…The reduction of Cr(VI) by ZVI is highly sensitive to the solution pH, as reported by numerous studies, the reduction rates increasing as the pH decreases (Alidokht et al 2011;Bowers et al 1986;Dutta et al 2010;Geng et al 2009b;Gould 1982;Ozer et al 1997;Powell and Puls 1997;Qian et al 2008;Weng et al 2007;Wu et al 2009). This is in accord with the stoichiometry of this reaction (Eq.…”

Section: Effect Of Phmentioning

confidence: 89%

“…Additionally, sorption of negatively charged Cr(VI) oxyanions onto ZVI is preferred at low pH because the ZVI surface is more positively charged . Under strong acidic conditions, Cr(VI) reduction was reported to be very fast Dutta et al 2010;Gheju and Iovi 2006), even instantaneous at pH 1 ). However, Chen et al (2007) observed that at pH 1, ZVI had a reduced lifetime than at pH 1.5, which was attributed to a higher reactivity of ZVI towards hydrogen ions at pH 1; consequently, optimum pH was shown at pH 1.5 instead of pH 1 .…”

Section: Effect Of Phmentioning

confidence: 99%

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Hexavalent Chromium Reduction with Zero-Valent Iron (ZVI) in Aquatic Systems

Gheju

2011

Water Air Soil Pollut

326

186

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Hexavalent chromium is a heavy metal used in a variety of industrial applications which is highly toxic to humans, animals, plants and microorganisms. Moreover, it is a well-established human carcinogen by the inhalation route of exposure and a possible human carcinogen by the oral route of exposure. Therefore, it should be removed from contaminated waters. Its reduction to trivalent chromium can be beneficial because a more mobile and more toxic chromium species is converted to a less mobile and less toxic form. During the last two decades, there has been important interest in using zero-valent iron (ZVI) as a Cr(VI)-reducing agent. A considerable volume of research has been carried out in order to investigate the mechanism and kinetics of Cr(VI) reduction with ZVI, as well as the influence of various parameters controlling the reduction efficiency. Therefore, the purpose of this review was to provide updated information regarding the developments and innovative approaches in the use of ZVI for the treatment of Cr(VI)-polluted waters.

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Section: Effect Of Phmentioning

confidence: 89%

Section: Effect Of Phmentioning

confidence: 99%

Hexavalent Chromium Reduction with Zero-Valent Iron (ZVI) in Aquatic Systems

Gheju

2011

Water Air Soil Pollut

326

186

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“…Unfortunately, these reports co-exist in the literature with publications demonstrating that Fe 0 surface is universally covered by oxide layers [61][62][63][64][65][66], and that Fe 0 is additionally passivated with corrosion products during the remediation process [44,52,61,67,68]. Numerous recent studies, aimed to gain insight into the principles governing the removal of Cr VI in Fe 0 /H 2 O systems, have also presumed that this process is exclusively the result of direct electron transfer from Fe 0 to Cr VI [69][70][71][72][73][74][75][76][77][78][79]. Since the surface of commercially Fe 0 materials is permanently covered by an outer layer of low electric conductive air-formed oxides (hematite, maghemite) [64], the electron transport from Fe 0 to Cr VI should be severely inhibited [69][70][71][72][73][74][75][76][77][78][79].…”

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

confidence: 99%

“…Numerous recent studies, aimed to gain insight into the principles governing the removal of Cr VI in Fe 0 /H 2 O systems, have also presumed that this process is exclusively the result of direct electron transfer from Fe 0 to Cr VI [69][70][71][72][73][74][75][76][77][78][79]. Since the surface of commercially Fe 0 materials is permanently covered by an outer layer of low electric conductive air-formed oxides (hematite, maghemite) [64], the electron transport from Fe 0 to Cr VI should be severely inhibited [69][70][71][72][73][74][75][76][77][78][79]. Moreover, Fe 0 efficiency should significantly decrease during the time, as its surface is progressively covered with additional secondary mineral coatings that prevents penetration of the Cr VI and stops the electron transfer [11,[80][81][82].…”

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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“…There we had reported different aspects of the batch reaction with ZVI in the form of iron dust and potassium dichromate solution (Dutta et al 2010). In case of steel wool, iron filings or scrap iron, it is difficult to determine the geometry or surface area of such irregular-shaped reductant accurately, and therefore it is nearly impossible to propose any rate model for the surface-reduction process since the rate equation explicitly contains transient active surface area.…”

Section: Introductionmentioning

confidence: 99%

Commercial steel wool for reduction of hexavalent chromium in wastewater: batch kinetic studies and rate model

Mitra¹,

Banerjee²,

Sarkar³

et al. 2013

Int. J. Environ. Sci. Technol.

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The present study aims at searching the potential of commercial grade steel wool in reducing hexavalent chromium in aqueous phase under batch mode. About 30 % of the initial hexavalent chromium was found to reduce within 2 h at a pH of 3. However, on testing the combined effects of different process parameters, namely the solution pH, wool loading, etc., the optimum batch parametric condition has been fixed. A moving boundary type kinetic model, which takes into account the effect of passivation along with the direct reduction mechanism to simulate the gross uptake profile of Cr(VI) from the bulk solution is proposed. The effective pore diffusivity of Cr(VI) in commercial steel wool was determined by a suitable global optimization technique. Additionally, the model is also capable to simulate the decline of active external surface area of the wool caused by passivation with time. A good match of the experimental data and model-simulated transient bulk concentration of Cr(VI) (under optimum parametric condition only) establishes the general validity of the proposed model.

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Reduction of Hexavalent Chromium in Aqueous Medium with Zerovalent Iron

Cited by 20 publications

References 33 publications

Hexavalent Chromium Reduction with Zero-Valent Iron (ZVI) in Aquatic Systems

Hexavalent Chromium Reduction with Zero-Valent Iron (ZVI) in Aquatic Systems

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

Commercial steel wool for reduction of hexavalent chromium in wastewater: batch kinetic studies and rate model

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