Influences of nanoscale zero valent iron loadings and bicarbonate and calcium concentrations on hydrogen evolution in anaerobic column experiments

Paar, Hendrik; Ruhl, Aki Sebastian; Jekel, Martin

doi:10.1016/j.watres.2014.10.043

Cited by 20 publications

(5 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Assuming that these processes occur simultaneously, a quantification of each process using the numerical model can help to investigate the impact on the hydraulic system. An indication for a concomitance of the processes and thus a support to this model assumption was previously shown in qualitative observations of heterogeniously distributed porous deposits using scanning electron microscopy (Paar et al, 2015). The deposits were characterized by multilayered NZVI depositions with a thickness of several micrometers for particle concentrations of about 5 g/kg(sand) as well as single layers and particle-free regions.…”

Section: Accepted Manuscriptsupporting

confidence: 65%

Effect of injection velocity and particle concentration on transport of nanoscale zero-valent iron and hydraulic conductivity in saturated porous media

Strutz

Hornbruch

Dahmke

et al. 2016

Journal of Contaminant Hydrology

View full text Add to dashboard Cite

Section: Accepted Manuscriptsupporting

confidence: 65%

Effect of injection velocity and particle concentration on transport of nanoscale zero-valent iron and hydraulic conductivity in saturated porous media

Strutz

Hornbruch

Dahmke

et al. 2016

Journal of Contaminant Hydrology

View full text Add to dashboard Cite

“…Previous studies that have addressed this issue have relied mainly on measurement of H 2 that is formed from acid digestion of Fe(0). This assay has been performed by measuring the volume or pressure of H 2 gas produced , or concentration of dissolved H 2 by gas chromatography, , but the former requires large sample volumes and has low sensitivity and the latter requires special sample handling and relatively-specialized instrumentation. Even more specialized methods of determining Fe(0) include fitting of XRD and Mössbauer data. ,, In contrast, reduction of I2S provides an assay that is selective for Fe(0), requires only small sample volumes (<1 mL), provides immediate results, and can easily be implemented in the field.…”

Section: Resultsmentioning

confidence: 99%

Field Deployable Chemical Redox Probe for Quantitative Characterization of Carboxymethylcellulose Modified Nano Zerovalent Iron

Fan

Chen

Johnson

et al. 2015

Environ. Sci. Technol.

View full text Add to dashboard Cite

Nano zerovalent iron synthesized with carboxymethylcelluose (CMC-nZVI) is among the leading formulations of nZVI currently used for in situ groundwater remediation. The main advantage of CMC-nZVI is that it forms stable suspensions, which are relatively mobile in porous media. Rapid contaminant reduction by CMC-nZVI is well documented, but the fate of the CMC-nZVI (including "aging" and "reductant demand") is not well characterized. Improved understanding of CMC-nZVI fate requires methods with greater specificity for Fe(0), less vulnerability to sampling/recovery artifacts, and more practical application in the field. These criteria can be met with a simple and specific colorimetric approach using indigo-5,5'-disulfonate (I2S) as a chemical redox probe (CRP). The measured stoichiometric ratio for reaction between I2S and nZVI is 1.45 ± 0.03, suggesting complete oxidation of nZVI to Fe(III) species. However, near pH 7, reduction of I2S is diagnostic for Fe(0), because aqueous Fe(II) reduces I2S much more slowly than Fe(0). At that pH, adding Fe(II) increased I2S reduction rates by Fe(0), consistent with depassivation of nZVI, but did not affect the stoichiometry. Using the I2S assay to quantify changes in the Fe(0) content of CMC-nZVI, the rate of Fe(0) oxidation by water was found to be orders of magnitude faster than previously reported values for other types of nZVI.

show abstract

“…Commercial NZVI, Nanofer25, was purchased from Nano Iron (Czech Republic). The typical characteristics of Nanofer25 are described elsewhere. , The NZVI particles were suspended in deoxygenated water and dispersed by ultrasonicating the mixture for 30 min before use. Iron(II) sulfate (99%, Junsei Chemical Co., Japan) and Iron(III) sulfate (60–80%, Junsei Chemical Co., Japan) were used for preparing Fe 2+ (aq) and Fe 3+ (aq) solutions, respectively.…”

Section: Methodsmentioning

confidence: 99%

Activation of Persulfate by Nanosized Zero-Valent Iron (NZVI): Mechanisms and Transformation Products of NZVI

Kim

Ahn

Kim

et al. 2018

Environ. Sci. Technol.

314

View full text Add to dashboard Cite

The mechanisms involved in the activation of persulfate by nanosized zero-valent iron (NZVI) were elucidated and the NZVI transformation products identified. Two distinct reaction stages, in terms of the kinetics and radical formation mechanism, were found when phenol was oxidized by the persulfate/NZVI system. In the initial stage, lasting 10 min, Fe was consumed rapidly and sulfate radicals were produced through activation by aqueous Fe. The second stage was governed by Fe catalyzed activation in the presence of aqueous Fe and iron (oxyhydr)oxides in the NZVI shells. The second stage was 3 orders of magnitude slower than the initial stage. An electron balance showed that the sulfate radical yield per mole of persulfate was more than two times higher in the persulfate/NZVI system than in the persulfate/Fe system. Radicals were believed to be produced more efficiently in the persulfate/NZVI system because aqueous Fe was supplied slowly, preventing sulfate radicals being scavenged by excess aqueous Fe. In the second stage, the multilayered shell conducted electrons, and magnetite in the shell provided electrons for the activation of persulfate. Iron speciation analysis (including X-ray absorption spectroscopy) results indicated that a shrinking core/growing shell model explained NZVI transformation during the persulfate/NZVI process.

show abstract

Influences of nanoscale zero valent iron loadings and bicarbonate and calcium concentrations on hydrogen evolution in anaerobic column experiments

Cited by 20 publications

References 26 publications

Effect of injection velocity and particle concentration on transport of nanoscale zero-valent iron and hydraulic conductivity in saturated porous media

Effect of injection velocity and particle concentration on transport of nanoscale zero-valent iron and hydraulic conductivity in saturated porous media

Field Deployable Chemical Redox Probe for Quantitative Characterization of Carboxymethylcellulose Modified Nano Zerovalent Iron

Activation of Persulfate by Nanosized Zero-Valent Iron (NZVI): Mechanisms and Transformation Products of NZVI

Contact Info

Product

Resources

About