Efficient Reductive Decomposition of Perfluorooctanesulfonate in a High Photon Flux UV/Sulfite System

Gu, Yu; Dong, Wenyi; Luo, Cheng; Liu, Tongzhou

doi:10.1021/acs.est.6b03261

Cited by 187 publications

(150 citation statements)

References 47 publications

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“…Recently, efficient degradation of some halogenated organic compounds (HOCs) and hazardous oxoanions was achieved through UV-activated (bi)sulfite (S(IV)) reduction (abbreviated as UV/S(IV)) [1][2][3], which is classified as a hydrated electron (e − aq )-based advanced reduction process (e − aq -ARP). However, besides the valid concentration of S(IV) (main precursor of e − aq ), UV photon absorbance by S(IV) dominates the production efficiency of e − aq for this reduction process [4].…”

Section: Introductionmentioning

confidence: 99%

Fast Degradation of Monochloroacetic Acid by BiOI-Enhanced UV/S(IV) Process: Efficiency and Mechanism

Wang

Liu

2019

Catalysts

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Iodide ( I − ) could promote ultraviolet-activated S(IV) processes (UV/S(IV)) and degrade aqueous halogenated organic compounds and hazardous oxoanions. With the interest of promoting use of this technology, this study investigated the feasibility of using bismuth oxyiodide (BiOI) as an I − source to enhance UV/S(IV) where monochloroacetic acid (MCAA) was selected as a testing model compound. Degradation of MCAA by UV/S(IV) increased by 50% in presence of BiOI. Results of competitive kinetics indicated that the promotion effect brought by BiOI mainly originated from its sustainable release of I − , and subsequent enhanced generation of hydrated electrons. Electron spin resonance detection and fluorescence characterization proved increased formation of sulfite radical, resulting from sulfite oxidation by UV-excited BiOI. However, the sulfite radical only made a small contribution (9%) to MCAA degradation due to its moderate reactivity toward MCAA (4.2 × 105 M−1·s−1). UV/S(IV) combined with BiOI significantly decreasing the biotoxicity of MCAA solution. BiOI can be regenerated using I − -containing solution. Our findings provide evidence that BiOI is a promising I − source and photocatalyst, which progresses the I − -assisted UV/S(IV) process towards practical application.

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Section: Introductionmentioning

confidence: 99%

Fast Degradation of Monochloroacetic Acid by BiOI-Enhanced UV/S(IV) Process: Efficiency and Mechanism

Wang

Liu

2019

Catalysts

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“…They also showed that NO 3 − has a negative influence on the degradation of PFOA. Gu et al used a similar system and degraded 98% of PFOS at 25 °C and a pH of 9.2 with a defluorination rate of approximately 50% after 30 min [ 88 ]. Bentel and co-workers operated the UV/sulphite system with a higher pH of 12 [ 75 ].…”

Section: State-of-the-art Liquid Reactionsmentioning

confidence: 99%

Reductive Defluorination and Mechanochemical Decomposition of Per- and Polyfluoroalkyl Substances (PFASs): From Present Knowledge to Future Remediation Concepts

Roesch

Vogel

Simon

2020

IJERPH

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Over the past two decades, per- and polyfluoroalkyl substances (PFASs) have emerged as worldwide environmental contaminants, calling out for sophisticated treatment, decomposition and remediation strategies. In order to mineralize PFAS pollutants, the incineration of contaminated material is a state-of-the-art process, but more cost-effective and sustainable technologies are inevitable for the future. Within this review, various methods for the reductive defluorination of PFASs were inspected. In addition to this, the role of mechanochemistry is highlighted with regard to its major potential in reductive defluorination reactions and degradation of pollutants. In order to get a comprehensive understanding of the involved reactions, their mechanistic pathways are pointed out. Comparisons between existing PFAS decomposition reactions and reductive approaches are discussed in detail, regarding their applicability in possible remediation processes. This article provides a solid overview of the most recent research methods and offers guidelines for future research directions.

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“…What's more, a short electron pathway between the GQDs interior and the surface due to the quantum size can enhance the electron transfer as well [39]. GQDs acted as the electron 15 donors in this process, in which electrons can be easily transferred to the surface of SiC nanoparticles. And then PFOS, which accumulated on the surface of SiC due to the surface-active properties, would act as the final electron acceptor for the electron-withdrawing property of sulfonate group.…”

Section: Figure 5 Herementioning

confidence: 99%

“…, the branched PFOS decomposed much faster than the linear isomers [15,22]. It was because that photon and e aq directly reacted with PFOS molecule in solution, and the C-F bond in branched isomers was more vulnerable to reductive decomposition than the linear isomers for the higher electron affinity [41].…”

Section: -mentioning

confidence: 99%

“…According to the previous researches, PFOS decomposition started with the cleavage of -F 2 C-SO 3 H bond, thus the focus of PFOS decomposition was how to realize initial activation of sulfonate group [13,14]. Sulfonate group in PFOS is 4 recalcitrant to traditional advanced oxidation processes (AOPs), while the hydrated electron (e aq -) induced reduction has been recently demonstrated to be effective to activate the sulfonate group [15,16]. However, due to the high reactivity of e aq with other coexistent oxidative species in solution, a large amount of chemical agent (molar concentration, I -: PFOS = 500 : 1) that can promote the e aq production was necessary to ensure fast decomposition kinetics [16].…”

Section: Introductionmentioning

confidence: 99%

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Directional electron transfer mechanisms with graphene quantum dots as the electron donor for photodecomposition of perfluorooctane sulfonate

Huang

Yin

et al. 2017

Chemical Engineering Journal

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Graphene quantum dots (GQDs) were synthesized via the oxygen-driven unzipping of graphene under ultra-high frequency ultrasonication, and then attached to the SiC nanoparticles by the hydrothermal method to form the SiC/GQDs nanocomposites. The SiC/GQDs exhibited superior photoactivity over the decomposition of perfluorooctane sulfonate (C 8 F 17 SO 3 H, PFOS), which was even harder to decompose than perfluorooctanoic acid (PFOA). This work presented the first instance of employing photoexcited semiconductor nanomaterials to realize the improvement from the activation of the -F 2 C-COOH bond in PFOA to the activation of -F 2 C-SO 3 H in PFOS. The decomposition rate constants (k) of 2-CF 3 -PFOS, 6-CF 3 -PFOS and linear-PFOS with SiC/GQDs were 0.127 h −1 , 0.115 h −1 , 0.098 h −1 , and the corresponding half-lives were 5.5 h, 6.0 h, 7.1 h, respectively. The ratio of k (the branched isomers : the linear isomers) significantly reduced from the 967 times via vacuum ultraviolet (VUV) photolysis to the same order of magnitude in this work.The X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) were conducted to investigate the electronic properties of SiC/GQDs, revealing the centermost directional electron transfer process during the reaction. The photogenerated electron originated from the π-π* transition of the C=C bond and the n-π* transition of the C=O bond under UV excitation, transferred to SiC nanoparticles due to the heterojunction structure of SiC/GQDs, and then further transferred to the accumulated PFOS on the surface of SiC/GQDs for the electron-withdrawing property of sulfonate group, leading to the critical activation of sulfonate group. The decomposition mechanisms of PFOS involved the ionic headgroup cleavage, hydrolysis, hydrodefluorination, and the C-C bond scission.

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Efficient Reductive Decomposition of Perfluorooctanesulfonate in a High Photon Flux UV/Sulfite System

Cited by 187 publications

References 47 publications

Fast Degradation of Monochloroacetic Acid by BiOI-Enhanced UV/S(IV) Process: Efficiency and Mechanism

Fast Degradation of Monochloroacetic Acid by BiOI-Enhanced UV/S(IV) Process: Efficiency and Mechanism

Reductive Defluorination and Mechanochemical Decomposition of Per- and Polyfluoroalkyl Substances (PFASs): From Present Knowledge to Future Remediation Concepts

Directional electron transfer mechanisms with graphene quantum dots as the electron donor for photodecomposition of perfluorooctane sulfonate

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