Three Kinetic Patterns for the Oxidation of Emerging Organic Contaminants by Fe(VI): The Critical Roles of Fe(V) and Fe(IV)

Wang, Shuchang; Deng, Yang; Shao, Bin; Zhu, Jiahui; Hu, Zixin; Guan, Xiaohong

doi:10.1021/acs.est.1c03813

Cited by 56 publications

(30 citation statements)

References 43 publications

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“…This assessment agrees with the reactivity of Fe IV and Fe VI with pollutants (see Figure A). Recently, kinetic analysis was conducted to determine the role of Fe V and Fe IV in the oxidation of organics by Fe VI O 4 2– …”

Section: Experimental Approaches To Identify Iron Intermediatesmentioning

confidence: 99%

“…Recently, kinetic analysis was conducted to determine the role of Fe V and Fe IV in the oxidation of organics by Fe VI O 4 2− . 205 Overall, kinetic modeling is a useful tool to elucidate the mechanisms of the oxidation reactions of Fe VI O 4 2− with pollutants; however, great care must be taken in analyzing the data and necessitates robust statistical analysis.…”

Section: ■ Activation Of Ferrate(vi)mentioning

confidence: 99%

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Reactive High-Valent Iron Intermediates in Enhancing Treatment of Water by Ferrate

Sharma

Feng

Dionysiou

et al. 2021

Environ. Sci. Technol.

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Efforts are being made to tune the reactivity of the tetraoxy anion of iron in the +6 oxidation state (FeVIO4 2–), commonly called ferrate, to further enhance its applications in various environmental fields. This review critically examines the strategies to generate highly reactive high-valent iron intermediates, FeVO4 3– (FeV) and FeIVO4 4– or FeIVO3 2– (FeIV) species, from FeVIO4 2–, for the treatment of polluted water with greater efficiency. Approaches to produce FeV and FeIV species from FeVIO4 2– include additions of acid (e.g., HCl), metal ions (e.g., Fe(III)), and reductants (R). Details on applying various inorganic reductants (R) to generate FeV and FeIV from FeVIO4 2– via initial single electron-transfer (SET) and oxygen-atom transfer (OAT) to oxidize recalcitrant pollutants are presented. The common constituents of urine (e.g., carbonate, ammonia, and creatinine) and different solids (e.g., silica and hydrochar) were found to accelerate the oxidation of pharmaceuticals by FeVIO4 2–, with potential mechanisms provided. The challenges of providing direct evidence of the formation of FeV/FeIV species are discussed. Kinetic modeling and density functional theory (DFT) calculations provide opportunities to distinguish between the two intermediates (i.e., FeIV and FeV) in order to enhance oxidation reactions utilizing FeVIO4 2–. Further mechanistic elucidation of activated ferrate systems is vital to achieve high efficiency in oxidizing emerging pollutants in various aqueous streams.

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Section: Experimental Approaches To Identify Iron Intermediatesmentioning

confidence: 99%

Section: ■ Activation Of Ferrate(vi)mentioning

confidence: 99%

Reactive High-Valent Iron Intermediates in Enhancing Treatment of Water by Ferrate

Sharma

Feng

Dionysiou

et al. 2021

Environ. Sci. Technol.

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“…18 Generally, a second order reaction rate law is used to describe the Fe(VI) oxidation of organic compounds. 19 For most compounds, the second order reaction rate (k app ) increases with the decrease of solution pH, and the k app under weak acidic or neutral conditions is 1−2 orders of magnitude higher than that under alkaline conditions. 17 Recently, attention has been paid to the performance of Fe(VI) under acidic conditions.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Most studies focusing on Fe(VI) oxidation were carried out under neutral and alkaline conditions since Fe(VI) is relatively unstable and quickly self-decays in acidic solutions . Generally, a second order reaction rate law is used to describe the Fe(VI) oxidation of organic compounds . For most compounds, the second order reaction rate ( k app ) increases with the decrease of solution pH, and the k app under weak acidic or neutral conditions is 1–2 orders of magnitude higher than that under alkaline conditions .…”

Section: Introductionmentioning

confidence: 99%

Reinvestigation of Ferrate(VI) Oxidation of Bisphenol A over a Wide pH Range

et al. 2021

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Ferrate (Fe(VI), K 2 FeO 4 ) has attracted much attention in water treatment for its high redox potential, especially under acidic conditions. Although interests have been arising in the performance of Fe(VI) at pH below 7.0, a contradicting trend of second order reaction rates (k app ) was observed at acidic conditions, and the reactive species (i.e., high-valent iron species or hydroxyl radicals (HO • )) of Fe(VI) oxidation at acidic pH remains unclear. Thus, the kinetics of Fe(VI) oxidizing bisphenol A (BPA) under a wide pH range was reinvestigated. The k app value of Fe(VI) with BPA strongly depends on pH, which increased from 7.31 × 10 1 to 2.44 × 10 3 M −1 s −1 with pH decreasing from 10.0 to 3.0. Moreover, high-valent iron species were identified as the reactive species, i.e., Fe(VI), Fe(V), and Fe(IV), in both alkaline and acidic solutions, while HO • was identified as the secondary reactive species at acidic conditions with negligible contribution. Theoretical calculation was used to predict the reactive sites, and similar degradation products of BPA were identified under both acidic and alkaline conditions, ascribed to the similar reactive species. Toxicity assessment based on the Toxicity Estimation Software Tool suggested that Fe(VI) can alleviate the bioaccumulation toxicity efficiently. Humic acid (0.2−2.0 mgC L −1 ) and ubiquitous anions (1.0 mM) showed no obvious adverse effect on Fe(VI) oxidation while 1.0 mM Fe 3+ or Cu 2+ could accelerate it, and Fe(VI) showed a promising performance for the abatement of BPA in real waters.

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“…Currently, 29% of the global population (∼2.2 billion people) has limited access to safely managed drinking water services, especially in sparsely populated regions. , With rapid urbanization, the pollution of drinking water sources is aggravated by emerging contaminants such as pharmaceuticals, endocrine disruptors, perfluorinated compounds, and disinfection byproducts, − which is becoming more complex and more difficult and costly to treat. Advanced oxidation processes (AOPs) are appealing treatment options as decentralized approaches to overcome the above-mentioned fundamental obstacles.…”

Section: Introductionmentioning

confidence: 99%

Electronic Control of Traditional Iron–Carbon Electrodes to Regulate the Oxygen Reduction Route to Scale Up Water Purification

Wang

Xiao

Shen

et al. 2022

Environ. Sci. Technol.

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Shifting four-electron (4e–) oxygen reduction in fuel cell technology to a two-electron (2e–) pathway with traditional iron–carbon electrodes is a critical step for hydroxyl radical (HO•) generation. Here, we fabricated iron–carbon aerogels with desired dimensions (e.g., 40 cm × 40 cm) as working electrodes containing atomic Fe sites and Fe3C subnanoclusters. Electron-donating Fe3C provides electrons to FeN4 through long-range activation for achieving the ideal electronic configuration, thereby optimizing the binding energy of the *OOH intermediate. With an iron–carbon aerogel benefiting from finely tuned electronic density, the selectivity of 2e– oxygen reduction increased from 10 to 90%. The resultant electrode exhibited unexpectedly efficient HO• production and fast elimination of organics. Notably, the kinetic constant k M for sulfamethoxazole (SMX) removal is 60 times higher than that in a traditional iron–carbon electrode. A flow-through pilot device with the iron–carbon aerogel (SA-Fe0.4NCA) was built to scale up micropolluted water decontamination. The initial total organic carbon (TOC) value of micropolluted water was 4.02 mg L–1, and it declined and maintained at 2.14 mg L–1, meeting the standards for drinking water quality in China. Meanwhile, the generation of emerging aromatic nitrogenous disinfection byproducts (chlorophenylacetonitriles) declined by 99.2%, satisfying the public safety of domestic water. This work provides guidance for developing electrochemical technologies to satisfy the flexible and economic demand for water purification, especially in water-scarce areas.

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Three Kinetic Patterns for the Oxidation of Emerging Organic Contaminants by Fe(VI): The Critical Roles of Fe(V) and Fe(IV)

Cited by 56 publications

References 43 publications

Reactive High-Valent Iron Intermediates in Enhancing Treatment of Water by Ferrate

Reactive High-Valent Iron Intermediates in Enhancing Treatment of Water by Ferrate

Reinvestigation of Ferrate(VI) Oxidation of Bisphenol A over a Wide pH Range

Electronic Control of Traditional Iron–Carbon Electrodes to Regulate the Oxygen Reduction Route to Scale Up Water Purification

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