Sulfidation mitigates the passivation of zero valent iron at alkaline pHs: Experimental evidences and mechanism

Gu, Yawei; Gong, Li; Qi, Jianlong; Cai, Shichao; Tu, Wenxin; He, Feng

doi:10.1016/j.watres.2019.04.061

Cited by 112 publications

(83 citation statements)

References 73 publications

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“…HEPES buffer (50 mM) was typically used to set the pH of the reaction solution at 7−11, while 2-(Nmorpholino)ethanesulfonic acid (MES) buffer (50 mM) was used to set the pH of the solution at 4−6. 11 For respike, pH, and the real groundwater experiments, 0.05 mL of an aqueous sample was withdrawn periodically and transferred into 1 mL of hexane in a 2 mL GC vial for TCE extraction. The extract was analyzed for TCE dechlorination using an Agilent 7890A GC equipped with an electron capture detector (ECD).…”

Section: ■ Introductionmentioning

confidence: 99%

FeN_X(C)-Coated Microscale Zero-Valent Iron for Fast and Stable Trichloroethylene Dechlorination in both Acidic and Basic pH Conditions

Gong

Qiu

Tratnyek

et al. 2021

Environ. Sci. Technol.

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FeN X in Fe single-atom catalysts can be the active site for adsorption and activation of reactants. In addition, FeN X species have been shown to facilitate electron transfer between Fe and the carbon supports used in newly developed metal−air batteries. We hypothesized that the combination of FeN X species with granular zero-valent iron (ZVI) might result in catalyzed reductive decontamination of groundwater contaminants such as trichloroethylene (TCE). Here, such materials synthesized by ball milling microscale ZVI with melamine and the resulting N species were mainly in the form of pyridinic, pyrrolic, and graphitic N. This new material (abbreviated as N−C-mZVI bm ) dechlorinated TCE at higher rates than bare mZVI bm (about 3.5-fold) due to facilitated electron transfer through (or around) the surface layer of iron oxides by the newly formed Fe−N X (C). N−C-mZVI bm gave higher k TCE (0.4−1.14 day −1 ) than mZVI bm (0−0.4 day −1 ) over a wide range of pH values (4− 11). Unlike most ZVI systems, k TCE for N−C-mZVI bm increased with increasing pH values. This is because the oxide layer that passivates Fe 0 at a high pH is disrupted by Fe−N X (C) formed on N−C-mZVI bm , thereby allowing TCE dechlorination and HER under basic conditions. Serial respike experiments gave no evidence of decreased performance of N−C-mZVI bm , showing that the advantages of this material might remain under field applications.

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Section: ■ Introductionmentioning

confidence: 99%

FeN_X(C)-Coated Microscale Zero-Valent Iron for Fast and Stable Trichloroethylene Dechlorination in both Acidic and Basic pH Conditions

Gong

Qiu

Tratnyek

et al. 2021

Environ. Sci. Technol.

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“…When the solution pH increased from 6 to 9, the 3 e of ball milled mZVI increased from $1% to 5%, while that by ball milled, suldated mZVI increased from $3% to 20%. 38 The results further demonstrate that increased pH inhibits the rate of the HER more than that of TCE dechlorination. This effect still has to be veried for more classes of organohalide COCs.…”

Section: Effects Of Geochemistry On Electron Efficiencymentioning

confidence: 81%

“…Due to all of these advantages, this product-based approach is the most frequently adopted to calculate electron efficiency. 20,21,[37][38][39][40] Nevertheless, this method still has shortcomings. The most signicant one is that if oxygen is present (i.e., oxic conditions), the method is less useful because the products of reaction with oxygen, such as oxyhydroxide precipitates and OH À , are not easily quantied.…”

Section: Quantication Of N Tmentioning

confidence: 99%

Quantifying the efficiency and selectivity of organohalide dechlorination by zerovalent iron

Gong

Fan

et al. 2020

Environ. Sci.: Processes Impacts

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“…The opposite observation was reported for TCE degradation with sulfidated particles, where the constant rate increased from 0.104 h -1 at pH 7 to 0.137 h -1 at pH 9 (Rajajayavel and Ghoshal 2015). Hence, it is suggested that sulfidated particles would be an efficient reagent for the remediation of groundwater at near-neutral pH (Dong et al 2018c;Gu et al 2019). 5.1 0.088 h -1 6.8 0.073 h -1 9.2 0.052 h -1 13.0 0.052 h -1 log k = -0.058 pH -0.755 (3.2 < pH < 9.3)…”

Section: Phmentioning

confidence: 87%

In Situ Chemical Reduction of Chlorinated Organic Compounds

Rodrigues

Betelu

Colombano

et al. 2020

Applied Environmental Science and Engineering for a Sustainable Future

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Chlorinated organic compounds (COCs) are common anthropogenic contaminants of soil and groundwater. COCs were industrially produced for different applications, such as dry cleaning, degreasing, or as pesticides. The presence of COCs in the environment is a major concern because of their toxicity and persistence.The most widely used method for their remediation is the conventional pump-and-treat system. However, this technology can hardly achieve a complete remediation because of geological characteristics and the presence of pore space pollution/adsorbed pollution, leading to a residual saturation. Hence, in addition to the improvement of pump-and-treat systems, in situ chemical processes have been largely developed. These chemical processes involve the injection of chemical reagents for the removal of residual source pollution and/or the treatment of plume contamination. Chemical degradation of COCs can be achieved by oxidative or reductive processes. If chemical oxidation has been first developed for in situ application, chemical reduction is one of the most important emerging remediation techniques for COCs treatment. Due to the electronegative character of chlorine substituents, COCs can effectively be transformed via reductive pathways. Moreover, reductive dechlorination has shown higher efficiency on highly chlorinated compounds. This chapter focuses on the presentation of the chemical reduction of the most common COCs pollutants, followed by kinetic and mechanistic approaches related to the use of iron-based particles. Developments on in situ chemical reduction technologies in order to enhance remediation rates are also exposed. Influence of environmental conditions for in situ applications is then developed. Finally, a case study is presented.

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Sulfidation mitigates the passivation of zero valent iron at alkaline pHs: Experimental evidences and mechanism

Cited by 112 publications

References 73 publications

FeN_X(C)-Coated Microscale Zero-Valent Iron for Fast and Stable Trichloroethylene Dechlorination in both Acidic and Basic pH Conditions

FeN_X(C)-Coated Microscale Zero-Valent Iron for Fast and Stable Trichloroethylene Dechlorination in both Acidic and Basic pH Conditions

Quantifying the efficiency and selectivity of organohalide dechlorination by zerovalent iron

In Situ Chemical Reduction of Chlorinated Organic Compounds

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Sulfidation mitigates the passivation of zero valent iron at alkaline pHs: Experimental evidences and mechanism

Cited by 112 publications

References 73 publications

FeNX(C)-Coated Microscale Zero-Valent Iron for Fast and Stable Trichloroethylene Dechlorination in both Acidic and Basic pH Conditions

FeNX(C)-Coated Microscale Zero-Valent Iron for Fast and Stable Trichloroethylene Dechlorination in both Acidic and Basic pH Conditions

Quantifying the efficiency and selectivity of organohalide dechlorination by zerovalent iron

In Situ Chemical Reduction of Chlorinated Organic Compounds

Contact Info

Product

Resources

About

FeN_X(C)-Coated Microscale Zero-Valent Iron for Fast and Stable Trichloroethylene Dechlorination in both Acidic and Basic pH Conditions

FeN_X(C)-Coated Microscale Zero-Valent Iron for Fast and Stable Trichloroethylene Dechlorination in both Acidic and Basic pH Conditions