Transformation and composition evolution of nanoscale zero valent iron (nZVI) synthesized by borohydride reduction in static water

Liu, Airong; Liu, Jing; Zhang, Wei‐xian

doi:10.1016/j.chemosphere.2014.09.026

Cited by 171 publications

(75 citation statements)

References 31 publications

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“…After an aging time of 10 h, the loss of the ZVI core and oxide shell was observed. It was reported that the oxidation of ZVI in the presence of dissolved oxygen is due to the outward diffusion and dissolution of Fe atoms from the metallic core (Yan et al 2013;Liu et al 2015). These results were additionally confirmed by XRD analysis.…”

Section: Role Of Fe(ii) For Achieving Se(vi) Removal Without Zvisupporting

confidence: 77%

Selenate removal by zero-valent iron in oxic condition: the role of Fe(II) and selenate removal mechanism

Yoon

Bang²,

Kim

et al. 2015

Environ Sci Pollut Res

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In this study, batch experiments were conducted to investigate the effect of the concentration of ferrous [Fe(II)] ions on selenate [Se(VI)] removal using zero-valent iron (ZVI). The mechanism of removal was investigated using spectroscopic and image analyses of the ZVI-Fe(II)-Se(VI) system. The test to remove 50 mg/L of Se(VI) by 1 g/L of ZVI resulted in about 60% removal of Se(VI) in the case with absence of Fe(II), but other tests with the addition of 50 and 100 mg/L of the Fe(II) had increased the removal efficiencies about 93 and 100% of the Se(VI), respectively. In other batch tests with the absence of ZVI, there were little changes on the Se(VI) removal by the varied concentration of the Fe(II). From these results, we found that Fe(II) ion plays an accelerator for the reduction of Se(VI) by ZVI with the stoichiometric balance of 1.4 (=nFe(2+)/nSe(6+)). Under anoxic conditions, the batch test revealed about 10% removal of the Se(VI), indicating that the presence of dissolved oxygen increased the kinetics of Se(VI) removal due to the Fe(II)-containing oxides on the ZVI, as analyzed by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS). The X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) spectra also showed that the reductive process of Se(VI) to Se(0)/Se(-II) occurred in the presence of the both ZVI and Fe(II). The final product of iron corrosion was lepidocrocite (γ-FeOOH), which acts as an electron transfer barrier from Fe(0) core to Se(VI). Therefore, the addition of Fe(II) enhanced the reactivity of ZVI through the formation of iron oxides (magnetite) favoring electron transfer during the removal of Se(VI), which was through the exhaustion of the Fe(0) core reacted with Se(VI).

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Section: Role Of Fe(ii) For Achieving Se(vi) Removal Without Zvisupporting

confidence: 77%

Selenate removal by zero-valent iron in oxic condition: the role of Fe(II) and selenate removal mechanism

Yoon

Bang²,

Kim

et al. 2015

Environ Sci Pollut Res

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“…Similarly, highly concentrated slurries (300 ZVI g·L -1 ) with or without a very low stirring speed together with a high pH have shown similar behaviour [13,31]. In contrast, if the slurry is diluted, buffered to low pH, with significant stirring speed or with a significant presence of oxygen, the loss of Fe(0) is much more dramatic at similar aging times [10,28,37,38]. These results thus indicate that the nZVI core (i.e., metallic iron) is not significantly affected during the activation process.…”

Section: Characterization Of Un-activated and Activated Particlesmentioning

confidence: 97%

“…It is known that water aging under aerobic conditions, as in the present case, leads to an increase in the SSA [29] and that the SSA could increase during interaction with pollutants [11,39]. It must be taken into account that nZVI obtained by the gas reduction process has a different reaction mechanism to nZVI particles obtained by borohydride reduction and a smaller increase in SSA would be expected [27,38]. As can be seen, the SSA increased with the activation process in all cases:…”

Section: Characterization Of Un-activated and Activated Particlesmentioning

confidence: 99%

Activation process of air stable nanoscale zero-valent iron particles

Ribas

Černík

Benito

et al. 2017

Chemical Engineering Journal

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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.

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“…The factors influencing NZVI toxicity are size as well as the reactions of the iron nanomaterial including corrosion and transformation processes, ferrous ions release, oxygen consumption and generation of reactive oxygen species (Scown et al, 2010;Zhu et al, 2012)., The production of oxidation enhancing entities such as hydroxides, carbonates and sulfates is facilitated (Liu et al, 2015;Stumm and Morgan, 2012). Next to oxygen depletion, ferrous ions might be responsible for toxicity as was shown in various studies (Chen et al, 2012;Keenan et al, 2009;Keller et al, 2012;Vuori, 1995).…”

Section: Modes Of Nzvi Toxicitymentioning

confidence: 98%

The ecotoxic potential of a new zero-valent iron nanomaterial, designed for the elimination of halogenated pollutants, and its effect on reductive dechlorinating microbial communities

Schiwy

Maes

Koske

et al. 2016

Environmental Pollution

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Transformation and composition evolution of nanoscale zero valent iron (nZVI) synthesized by borohydride reduction in static water

Cited by 171 publications

References 31 publications

Selenate removal by zero-valent iron in oxic condition: the role of Fe(II) and selenate removal mechanism

Selenate removal by zero-valent iron in oxic condition: the role of Fe(II) and selenate removal mechanism

Activation process of air stable nanoscale zero-valent iron particles

The ecotoxic potential of a new zero-valent iron nanomaterial, designed for the elimination of halogenated pollutants, and its effect on reductive dechlorinating microbial communities

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