Anaerobic Reaction of Nanoscale Zerovalent Iron with Water: Mechanism and Kinetics

Filip, Jan; Karlický, František; Marušák, Zdeněk; Lazar, Petr; Černík, Miroslav; Otyepka, Michal; Zbořil, Radek

doi:10.1021/jp501846f

Cited by 114 publications

(92 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the one hand it has been clearly demonstrated that long-term water exposure decreases the reactivity of nZVI against a wide range of pollutants due to the growing of the oxide/hydroxide shell [11,13,18,[25][26][27][28][29], which leads to a passivation of the particles and it is commonly known as water aging [30].…”

Section: Introductionmentioning

confidence: 99%

Activation process of air stable nanoscale zero-valent iron particles

Ribas

Černík

Benito

et al. 2017

Chemical Engineering Journal

View full text Add to dashboard Cite

Nanoscale Zero Valent Iron (nZVI) represents a promising material for subsurface water remediation technology. However, dry, bare nZVI particles are highly reactive, being pyrophoric when they are in contact with air. The current trends of nZVI manufacturing lead to the surface passivation of dry nZVI particles with a thin oxide layer, which entails a decrease in their reactivity. In this work an activation procedure to recover the reactivity of air-stable nZVI particles is presented. The method consists of exposing nZVI to water for 36 hours just before the reaction with the pollutants. To assess the increase in nZVI reactivity based on the activation procedure, three types of nZVI particles with different oxide shell thicknesses have been tested for Cr(VI) removal. The two types of air-stable nZVI particles with an oxide shell thickness of around 3.4 and 6.5 nm increased their reactivity by a factor of 4.7 and 3.4 after activation, respectively. However, the pyrophoric nZVI particles displayed no significant improvement in reactivity. The improvement in reactivity is related mainly to the degradation of the oxide shell, which enhances electron transfer and leads secondarily to an increase in the specific surface area of the nZVI after the activation process. In order to validate the activation process, additional tests with selected chlorinated compounds demonstrated an increase in the degradation rate by activated nZVI particles.

show abstract

Section: Introductionmentioning

confidence: 99%

Activation process of air stable nanoscale zero-valent iron particles

Ribas

Černík

Benito

et al. 2017

Chemical Engineering Journal

View full text Add to dashboard Cite

show abstract

“…In aqueous solutions, nZVI reacts with water and dissolved oxygen to form ferrous iron and hydrogen gas (Equations 3.1 -3.2). (Nurmi et al, 2005, Filip et al, 2014. Magnetite is one of the main oxidized forms of iron formed on the surface of nZVI, but it is not considered a strong reductant for reductive dechlorination of organic compounds (Lee and Batchelor, 2002) Thus far, nZVI has been unable to dechlorinate 1,2-DCA Zhang, 2005, Song and.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Dechlorination of 1,2-Dichloroethane by Coupled Nano Iron-Dithionite Treatment

Garcia

Boparai

O'Carroll

2016

Environ. Sci. Technol.

View full text Add to dashboard Cite

1,2-dichloroethane (1,2-DCA) is a chlorinated solvent classified as a probable human carcinogen. Due to its extensive industrial applications, widespread contamination and recalcitrance towards abiotic dechlorination, 1,2-DCA remains a challenging compound for the remediation community and one of the great research interests. Batch experiments combining bimetallic or monometallic nZVI (stabilized or non-stabilized) with sodium dithionite were conducted for the degradation of 1,2-DCA. These experiments have yielded up to 92 % degradation of the initial 1,2-DCA concentration over the course of a year. Observed pseudo-first order rate constants (k obs ) range from 3.8 x 10 -3 to 7.8 x 10 -3 day -1 . Degradation was also achieved using magnetite and iron sulfide as the metal surface, with kobs values of 6.2 x 10 -3 and 4.7 x 10 -3 day -1 , respectively. Characterization analysis of the nZVI/dithionite nanoparticles shows that zero valent iron as such remains in solution after more than one year of reactivity and that iron sulfide is formed in solution. This novel treatment represents the first nZVI-based formulation to achieve nearly complete degradation of 1,2-DCA.

show abstract

“…50,51 The formation of Fe 3 O 4 in pure water is thermodynamically possible; the electrochemical equilibrium potential of the metal oxidation half reaction of Fe(OH) 2 53,54 who suggested that lepidocrocite (γ-FeOOH) is formed via oxidation of Fe II (aq) and subsequent precipitation. It may be possible that dissolved ferrous ions can be oxidized in the solution phase.…”

Section: Proposed Mechanism For Evolution Of Cs Corrosionmentioning

confidence: 99%

Inverse Crevice Corrosion of Carbon Steel: Effect of Solution Volume to Surface Area

Guo

et al. 2017

J. Electrochem. Soc.

View full text Add to dashboard Cite

Crevice corrosion of carbon steel was investigated in different exposure environments by performing coupon exposure and electrochemical tests. The extent of corrosion on the bold surface of a carbon steel crevice coupon was more severe at 80 • C than at 21 • C, in aerated rather than dearated solutions, and with γ-radiation present. In contrast to normal crevice corrosion, we observed 'inverse crevice corrosion' behavior, the phenomenon where it is the corrosion on the bold surface that is accelerated when coupled, rather than that on the crevice surface. The coupling current measured between a crevice and a bold electrode in an electrochemical cell was also negative. This inverse crevice corrosion behavior is attributed to a significantly lower metal cation dissolution capacity of the small occluded water volume in the crevice, compared to that of the bulk water volume over the bold surface. The reduction in dissolution capacity results in faster and earlier formation of a protective oxide layer. Corrosion of the bold and crevice surfaces evolves at different rates, leading to galvanically accelerated corrosion of the bold surface. The effect of γ-radiation on corrosion evolution in different solution environments leading to inverse crevice corrosion is discussed. Many countries, including Canada, are exploring long-term disposal of used nuclear fuel in a deep geological repository (DGR) using a multiple-barrier system, with a key barrier being the used fuel container (UFC).1-7 Certain UFC designs considered for disposal in a DGR consist of an inner vessel made of carbon steel (CS) or cast iron for structural strength, with an outer Cu shell or coating as an external corrosion barrier (e.g. the Swedish and Canadian UFC designs).3,8 The current Canadian UFC design consists of a pressure-vessel-grade CS pipe pre-coated with Cu. The vessel would be sealed by laser welding on site, in air, by attaching a pre-Cu-coated hemispherical CS head at one end. This would be followed by applying a Cu coating over the welded regions.9,10 A concern regarding the structural integrity of the inner CS vessels of this UFC design is localized corrosion.11 Moisture trapped inside a UFC could condense on the stressed regions near the welds and, for the Canadian design, within the gap between the hemispherical head and the body. This could lead to localized corrosion, a potential failure mechanism of the container.The environment inside the UFC will be initially humid and it will include a flux of ionizing radiation (and particularly γ-radiation), emitted from the decay of radionuclides in the used fuel. For the current Canadian UFC design the dose rate at the inner surface of a UFC is anticipated to be less than 100 Gy·h -1 (1 Gy = 1 J·kg -1 ). The dose rate is calculated to be 51 Gy·h -1 for 10-year old fuel and the dose rate will steadily decreases to 4.9 Gy·h -1 after the used fuel ages for 100 years. 12Interaction of matter with high energy photons or particles usually results in the absorbed energy being dissipated predominantly...

show abstract

Anaerobic Reaction of Nanoscale Zerovalent Iron with Water: Mechanism and Kinetics

Cited by 114 publications

References 52 publications

Activation process of air stable nanoscale zero-valent iron particles

Activation process of air stable nanoscale zero-valent iron particles

Enhanced Dechlorination of 1,2-Dichloroethane by Coupled Nano Iron-Dithionite Treatment

Inverse Crevice Corrosion of Carbon Steel: Effect of Solution Volume to Surface Area

Contact Info

Product

Resources

About