Reductive Dechlorination of Trichloroethene by Zero-valent Iron Nanoparticles: Reactivity Enhancement through Sulfidation Treatment

Han, Yuexin; Yan, Weile

doi:10.1021/acs.est.6b03997

Cited by 319 publications

(294 citation statements)

References 68 publications

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“…Sulfidation of NZVI has been hypothesized to facilitate electron transfer in previous studies. [ 29,30,41,59,60 ] However, the impact of sulfur amount and speciation on the electrochemical properties of SNZVI, and on their reactivity and selectivity has not been reported. We prepared electrodes by pressing pellets of NZVI and SNZVI onto Ti mesh and performed several electrochemical tests.…”

Section: Figurementioning

confidence: 99%

Sulfur Loading and Speciation Control the Hydrophobicity, Electron Transfer, Reactivity, and Selectivity of Sulfidized Nanoscale Zerovalent Iron

et al. 2020

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radionuclides. [12][13][14][15][16][17] However, NZVI is an indiscriminate reductant that also readily reduces water to form hydrogen gas (Fe 0 + 2H 2 O → Fe 2+ + 2OH − + H 2(g) ). [18] This unwanted side reaction consumes the reducing capacity of the NZVI, decreasing its reactive lifetime, and increases the amount and cost of NZVI required for remediation. Several approaches have been proposed to increase the reactivity or stability of NZVI during remediation, including encapsulating them with polymers or into silica matrices, [15,19] doping them with noble metals like Pd or Pt, [20,21] and supporting them onto carbon matrices like carbon nanotubes or graphene. [22,23] While these approaches improve the injectability of the materials into the subsurface, none have improved the selectivity of NZVI for contaminants over water while still maintaining high reactivity with the target groundwater contaminants. An ideal material for groundwater remediation should possess both high reactivity and selectivity, [24] where the contaminant outcompetes water for reactive sites.Recently, it was shown by us and others that the sulfidation of NZVI lowers its reactivity with water and other non-target hydrophilic contaminants (e.g., NO 3 − ), while increasing its reactivity with target contaminants like chlorinated solvents Sulfidized nanoscale zerovalent iron (SNZVI) is a promising material for groundwater remediation. However, the relationships between sulfur content and speciation and the properties of SNZVI materials are unknown, preventing rational design. Here, the effects of sulfur on the crystalline structure, hydrophobicity, sulfur speciation, corrosion potential, and electron transfer resistance are determined. Sulfur incorporation extended the nano-Fe 0 BCC lattice parameter, reduced the Fe local vacancies, and lowered the resistance to electron transfer. Impacts of the main sulfur species (FeS and FeS 2 ) on hydrophobicity (water contact angles) are consistent with density functional theory calculations for these FeS x phases. These properties well explain the reactivity and selectivity of SNZVI during the reductive dechlorination of trichloroethylene (TCE), a hydrophobic groundwater contaminant. Controlling the amount and speciation of sulfur in the SNZVI made it highly reactive (up to 0.41 L m −2 d −1 ) and selective for TCE degradation over water (up to 240 moles TCE per mole H 2 O), with an electron efficiency of up to 70%, and these values are 54-fold, 98-fold, and 160-fold higher than for NZVI, respectively. These findings can guide the rational design of robust SNZVI with properties tailored for specific application scenarios.Highly redox active materials are an important tool for the degradation of refractory organic water and soil contaminants. [1][2][3][4][5][6][7] Nanoscale zero valent (NZVI) has been used for in situ groundwater remediation for more than two decades. [8][9][10][11][12] NZVI is a strong reductant that readily dechlorinates chlorinated solvents and antibiotics, and reduces and immobilizes h...

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Section: Figurementioning

confidence: 99%

Sulfur Loading and Speciation Control the Hydrophobicity, Electron Transfer, Reactivity, and Selectivity of Sulfidized Nanoscale Zerovalent Iron

et al. 2020

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“…The oxidation behavior of nZVI in natural waters is likely to be affected by the water chemistry, such as pH and the presence of anions, multivalent cations, and natural organic matter (Dong, Zhao, et al, ; Kim et al, ; Reinsch et al, ). Besides, different modification methods (e.g., coating of surface stabilizer, bimetal decoration, and sulfidation treatment) have been developed to modify the surface of nZVI to enhance its stability and reactivity (Greenlee et al, ; Han & Yan, ; Kim, Murugesan, Kim, Tratnyek, & Chang, ; Yan, Herzing, Kiely, & Zhang, ). The varying surface properties may result in the different oxidation behavior of nZVI in aqueous environment.…”

Section: Physicochemical Transformation Of Nzvi In Watermentioning

confidence: 99%

“…Recently, the sulfide‐modified nZVI (S‐nZVI) has been developed and proved to be a better reducing reagent than nZVI (Dong, Zhang, et al, ; Han & Yan, ; He, Wilson, & Wilkin, ; Kim et al, ). As for the mechanisms for the improved ability to remove contaminants caused by the sulfide modification, researchers have proposed some mechanisms as follows: accelerated electron transfer mediated by the FeS layer, improved contaminant‐specific property (against reaction with water), and depassivation of iron surface (Dong, Hou, et al, ; Dong, Wang, et al, ; Han & Yan, ; Wang et al, ).…”

Section: Physicochemical Transformation Of Nzvi In Watermentioning

confidence: 99%

“…The formation of other Fe‐bearing mineral phases (e.g., siderite and vivianite) is also possible, which depends on the geochemical conditions under which the particles are exposed (Xie et al, ). Besides, the chemical compositions and physical structures of the aged nZVI also varied considerably among the different iron types (e.g., bare nZVI, surface‐coated nZVI, sulfide‐modified nZVI, and bimetallic iron nanoparticles) (Dong, Zhao, et al, ; Han & Yan, ; Kim et al, ; Liu et al, ; Sohn, Kang, Ahn, Woo, & Yang, ; Xie, Fang, Qiu, Tsang, & Liang, ).…”

Section: Introductionmentioning

confidence: 99%

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Aging of zero‐valent iron‐based nanoparticles in aqueous environment and the consequent effects on their reactivity and toxicity

Dong

Wang

et al. 2019

Water Environment Research

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A fundamental understanding of the long-term fate of nanoscale zero-valent iron (nZVI)-based particles in aqueous environment and the corresponding impacts on their reactivity and toxicity is essential for the responsible use and management of the nanoparticles in environmental applications. This paper comprehensively reviews the physicochemical transformations of nZVI-based particles and the consequent effects on the particle's reactivity and toxicity. The corrosions of nZVI in water under both anaerobic and aerobic conditions are summarized. The transformation of contaminant-bearing nZVI is also discussed. Besides, the factors influencing the transformation of nZVI (i.e., pH, typical anions and cations, natural organic matter, surface stabilizers, bimetal decoration, and sulfidation treatment) are summarized and discussed. In addition, the effects of particle aging on its reactivity and toxicity are discussed. Generally, the aging of nZVI-based particles would have negative impact on the removal of contaminants, especially for the degradation of organic pollutants. However, the aging process of nZVI-based particles would cause a significant reduction in their toxicity. It is suggested that the nZVI-based particles would finally transform to less toxic or benign materials (i.e., iron (oxyhydr)oxides) over time. Finally, future perspectives are proposed to better quantify and predict the transformation of nZVI-based particles in aqueous environment. © 2019 Water Environment Federation • Practitioner points• The corrosion rates and products of nZVI in water varied much under anaerobic and aerobic conditions. • Typical anions and cations, natural organic matter, and iron types are critical factors influencing the physicochemical transformation of nZVI. • The aging of nZVI would have negative impact its reactivity, especially for the degradation of organic pollutants. • Although the fresh nZVI exhibits obvious toxicity, the aging process would cause a significant reduction in its toxicity.

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“…For both substrates, complete dehalogenation occurred within 16 h under the experimental conditions employed. As noted for several other substrates the rates the dehalogenation by nFe 0 , 45,46 can be expressed in terms of pseudo first-order reactions. The apparent rate constants (k) are 0.34 ± 0.04 and 0.17 ± 0.01 h -1 for the brominated and chlorinated aromatic molecules, respectively.…”

Section: Degradation Of Trichloroethylene (Tce) In Methanol Suspensiomentioning

confidence: 99%

Polydimethylsiloxane as a Matrix for the Stabilization and Immobilization of Zero‑Valent Iron Nanoparticles. Applications to Dehalogenation of Environmentally Deleterious Molecules

Mercado¹,

Weiss²

2018

J. Braz. Chem. Soc.

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A wet-synthetic method is described to obtain magnetic, air-stable, zero-valent iron nanoparticles coated with an alkanedioic acid. The particles can be immobilized in an amino-substituted polysiloxane matrix to provide materials capable of dechlorinating, debrominating, and deiodinating a wide variety of halogenated organic molecules dissolved initially in a highly polar medium. The methodology involves diffusion of the organic molecules into the polysiloxane matrix, their reaction with the embedded iron nanoparticles, and then diffusion of the dehalogenated products back into the polar medium or into the air. Thus, the abilities of the coated particles, as suspensions or within an amino-substituted polysiloxane matrix crosslinked with succinic acid, to dehalogenate various organic molecules (especially the model compounds, bromobenzene and chlorobenzene), have been assessed. Data from several spectroscopic methods demonstrate that the particles are in a crystalline α-Fe phase surrounded by the diacid shell. The effect of embedding 10 wt.% of the particles in amino-substituted polysiloxane-diacid matrices with different COOH/NH 2 group ratios and the viscoelastic properties of the polymeric materials have been investigated as well. Potential uses of these gel-like materials to remove halogenated pollutants from various types of aquifers are mentioned.

show abstract

Reductive Dechlorination of Trichloroethene by Zero-valent Iron Nanoparticles: Reactivity Enhancement through Sulfidation Treatment

Cited by 319 publications

References 68 publications

Sulfur Loading and Speciation Control the Hydrophobicity, Electron Transfer, Reactivity, and Selectivity of Sulfidized Nanoscale Zerovalent Iron

Sulfur Loading and Speciation Control the Hydrophobicity, Electron Transfer, Reactivity, and Selectivity of Sulfidized Nanoscale Zerovalent Iron

Aging of zero‐valent iron‐based nanoparticles in aqueous environment and the consequent effects on their reactivity and toxicity

Polydimethylsiloxane as a Matrix for the Stabilization and Immobilization of Zero‑Valent Iron Nanoparticles. Applications to Dehalogenation of Environmentally Deleterious Molecules

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