Reduction of hexa-valent chromium with zero-valent iron: Batch kinetic studies and rate model

Mitra, Payel; Sarkar, Debasish; Chakrabarti, Sudipta; Dutta, Binay K.

doi:10.1016/j.cej.2011.03.037

Cited by 89 publications

(54 citation statements)

References 38 publications

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“…Several conventional physico-chemical methods, such as membrane filtration [8] , chemical precipitation [9][10] , ion exchange [11] , chemical oxidation or reduction [12] , electrochemical treatment [13] , solvent extraction [14] and activated carbon adsorption [15] have been used to remove heavy metals and other contaminants from the effluents. However, the applicability of these methods were limited especially in developing countries as they are not economical, require expensive equipments and again generate secondary waste.…”

Section: Introductionmentioning

confidence: 99%

Decontamination of Lead from aquatic environment by exploitation of floating macrophyte Azolla microphylla Kauf

Mishra¹,

Pradhan²,

Bihari³

et al. 2014

IOSRJESTFT

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Section: Introductionmentioning

confidence: 99%

Decontamination of Lead from aquatic environment by exploitation of floating macrophyte Azolla microphylla Kauf

Mishra¹,

Pradhan²,

Bihari³

et al. 2014

IOSRJESTFT

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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: 98%

“…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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“…However, the mixed Fe 3+ -Cr 3+ formation solubility was also lower and decreased the kinetic reaction at a lower pH solution. Cr 6+ removal can be influenced by iron geochemistry (dissolution and precipitation) despite the effects of H + generation [35].…”

Section: Effects Of Solution Phmentioning

confidence: 99%

Kinetic removal of Cr6+ by carboxymethyl cellulose-stabilized nano zerovalent iron particles

Ayob

Alias

Dahalan

et al. 2015

Maced. J. Chem. Chem. Eng.

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Carboxymethyl cellulose (CMC) was used in the chemical reduction method for producing dispersible nano zero-valent iron (nZVI) particles served as reactive, mobile and convenient adsorbent. CMC-stabilized nZVI particles at CMC:Fe 2+ = 0.0034 molar ratio were characterized using Fouriertransform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) assisted with probe ultrasonication dispersing tool. FTIR depicted that the CMC monomers were adsorbed onto nZVI particles primarily through carbonyl head groups via monodentate bonding. The botryoidally clusters were the predominant morphology of CMC-stabilized nZVI particles under SEM observation. Those spherical particles were evenly dispersed at sizes less than 100 nm under TEM analysis. nZVI particles stabilization with CMC (at CMC:Fe 2+ molar ratio of 0.005) prevented the aggregation and resulted in high catalytic reactivity observed at pseudo-first order constant value, K 1 of 0.0196 min 1 for Cr 6+ removal in aqueous solution. This study demonstrates that CMC-stabilized nZVI particle has the potential to become an effective agent for in situ subsurface environment remediation.Keywords: aggregation; CMC; kinetic Cr 6+ removal; stabilized nZVI particles; ultrasonication КИНЕТИЧКО ОТСТРАНУВАЊЕ НА Cr 6+ ВО ВОДЕН РАСТВОР НА НАНО-НУЛАВАЛЕНТНИ ЧЕСТИЧКИ НА ЖЕЛЕЗО СТАБИЛИЗИРАНИ СО КАРБОКСИМЕТИЛ ЦЕЛУЛОЗАКарбокисиметил целулоза (CMC) е употребена за хемиска редукција со која се добиваат честички на дисперзивно нулавалентно железо (nZVI) кое може да послужи како реактивен, мобилен и погоден апсорбент. Со CMC-стабилизираните честички на nZVI со моларен однос CMC:Fe 2+ = 0.0034 се карактеризирани со помош на Фуриеова трансформна инфрацрвена спектроскопија (FTIR), скенирачка електронска микроскопија (SEM) и трансмисиона електронска микроскопија (TEM) помогната со ултразвучна дисперзивна алатка. FTIR покажа дека мономерите на СМС се атсорбирани врз честичките на nZVI примарно преку карбонилните групи со монодентатно сврзување. Доминатна морфологија на CMC стабилизираните nZVI се ботриоидни кластери кои се определени со SEM. Овие сферни честички се рамномерно дисперзирани со големина помала од 100 nm како што покажува анализата со TEM. Честичките на nZVI стабилизирани со CMC (со моларен однос на CMC:Fe 2+ од 0.005) ја спречуваат агрегацијата што резултира со висока каталитичка реактивност која е забележана кај вредноста на константа за псевдо-прв ред, K 1 од 0.0196 min 1 при отстранување на Cr 6+ од водни раствори. Оваа студија покажува дека CMC стабилизираните честички на nZVI имаат потенцијал да се користат како ефикасно средство за in situ ремедијација на животната средина.Клучни зборови: агрегација; CMC; кинетичкко отстранување на Cr 6+

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Reduction of hexa-valent chromium with zero-valent iron: Batch kinetic studies and rate model

Cited by 89 publications

References 38 publications

Decontamination of Lead from aquatic environment by exploitation of floating macrophyte Azolla microphylla Kauf

Decontamination of Lead from aquatic environment by exploitation of floating macrophyte Azolla microphylla Kauf

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

Kinetic removal of Cr6+ by carboxymethyl cellulose-stabilized nano zerovalent iron particles

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