Removal of Chromium (VI) by Acid-Washed Zero-Valent Iron under Various Groundwater Geochemistry Conditions

Lai, Keith C. K.; Lo, Irene Man Chi

doi:10.1021/es071572n

Cited by 221 publications

(97 citation statements)

References 30 publications

(68 reference statements)

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“…The pathway for Cr(VI) removal in aqueous solution is summarized as follows. Removal of Cr(VI) by Fe 0 follows the pathway of sorption and reductive precipitation/immobilization (Lai and Lo 2008;Liu et al 2008 . Spectroscopic data showed that the Cr(III) precipitation can form Cr or Cr-Fe mixture such as oxides/hydroxides/oxyhydroxides (Powell et al 1995;Pratt et al 1997).…”

Section: The Reaction Mechanism Removing Of Cr(vi) By A-nzvimentioning

confidence: 99%

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Synthesis of agar-stabilized nanoscale zero-valent iron particles and removal study of hexavalent chromium

Jiao

Cheng

Fan

et al. 2014

Int. J. Environ. Sci. Technol.

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In this study, agar-stabilized nanoscale zerovalent iron (A-nZVI) was synthesized using a rheological phase reaction method. The structure and morphology of A-nZVI particles were investigated by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and Fourier-transform infrared spectrometry. Batch removal experiments showed that the pH value of solution, hexavalent chromium [Cr(VI)]/A-nZVI mass ratio and reaction time have significant effects on the removal of Cr(VI). A 100 % removal of Cr(VI) was achieved when applying 50 mg L -1 of Cr(VI) at the optimal pH value of 3 and the Cr(VI)/A-nZVI molar ratio of 0.025 with the reaction time of 2 h at room temperature. The removal rates of Cr(VI) were fitted to the modified pseudo-first-order kinetic equations with respect to Cr(VI) concentrations.

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Section: The Reaction Mechanism Removing Of Cr(vi) By A-nzvimentioning

confidence: 99%

“…Spectroscopic data showed that the Cr(III) precipitation can form Cr or Cr-Fe mixture such as oxides/hydroxides/oxyhydroxides (Powell et al 1995;Pratt et al 1997). These precipitations were mostly irregular strips, chick-footmark-like or boulder-like forms (Lai and Lo 2008 …”

Section: The Reaction Mechanism Removing Of Cr(vi) By A-nzvimentioning

confidence: 99%

Synthesis of agar-stabilized nanoscale zero-valent iron particles and removal study of hexavalent chromium

Jiao

Cheng

Fan

et al. 2014

Int. J. Environ. Sci. Technol.

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“…The standard electrode potential of Fe 0 , Cr(VI), and Cr ( respectively. Removal of Cr(VI) by Fe 0 follows the pathway of sorption and reductive precipitation/ immobilization (Lai and Lo 2008;Liu et al 2008). Initially, Cr(VI) gets adsorbed on the surface of Fe 0 where electron transfer takes place.…”

Section: Reduction Of Cr(vi) By Fe 0 Nanoparticlesmentioning

confidence: 99%

Removal of hexavalent chromium from contaminated ground water using zero-valent iron nanoparticles

Singh

Misra

Singh

2011

Environ Monit Assess

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Batch experiments were conducted on ground water samples collected from a site contaminated with Cr(VI) to evaluate the redox potential of zero-valent iron (Fe(0)) nanoparticles for remediation of Cr(VI)-contaminated ground water. For this, various samples of contaminated ground water were allowed to react with various loadings of Fe(0) nanoparticles for a reaction period of 60 min. Data showed 100% reduction of Cr(VI) in all the contaminated ground water samples after treatment with 0.20 gL(-1) of Fe(0) nanoparticles. An increase in the reduction of Cr(VI) from 45% to 100% was noticed with the increase in the loading of Fe(0) nanoparticles from 0.05 to 0.20 gL(-1). Reaction kinetics of Cr(VI) reduction showed pseudo first-order kinetics with rate constant in the range of 1.1 × 10(-3) to 3.9 × 10(-3) min(-1). This work demonstrates the potential utility of Fe(0) nanoparticles in treatment and remediation of Cr(VI)-contaminated water source.

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“…Even though reduction of Cr VI at the surface of secondary mineral layers was initially believed to be slow [88], recent studies revealed that, actually, Cr VI may be rapidly sequestrated at the surface of Fe II -bearing minerals containing structural Fe II and/or Fe II impurities, following an adsorption-reduction mechanism [96,97]. Cr VI adsorption onto positively charged iron and/or chromium oxyhidroxide layers surrounding Fe 0 particles was regarded not only as an intermediate step, but also as an important Cr VI removal mechanism by itself [98][99][100][101]. It has been shown that adsorption processes may contribute not only to the removal of Cr VI , but also to the removal of the resulted Cr III [61,86,92].…”

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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Removal of Chromium (VI) by Acid-Washed Zero-Valent Iron under Various Groundwater Geochemistry Conditions

Cited by 221 publications

References 30 publications

Synthesis of agar-stabilized nanoscale zero-valent iron particles and removal study of hexavalent chromium

Synthesis of agar-stabilized nanoscale zero-valent iron particles and removal study of hexavalent chromium

Removal of hexavalent chromium from contaminated ground water using zero-valent iron nanoparticles

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

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