Discerning the inefficacy of hydroxyl radicals during perfluorooctanoic acid degradation

Javed, Hassan; Lyu, Cong; Sun, Ruonan; Zhang, Danning; Alvarez, Pedro J. J.

doi:10.1016/j.chemosphere.2020.125883

Cited by 79 publications

(61 citation statements)

References 52 publications

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“…As it may be seen in Figure 6d, reaction media is quickly acidified. This is related to both the generation of short chain acids and the reaction between sulfate radicals and water to produce hydroxyl radicals, which also generates protons, as depicted in Equation (15). PFOA decay ( Figure 6a) was similar for all the runs.…”

Section: Hso + Ho • → So • + H Omentioning

confidence: 83%

“…Consequently, the substitution of all organic hydrogen for fluorine in PFOA makes these compounds inert to this kind of AOP. The non-reactivity of PFOA to HO • attack has been confirmed by various studies [13][14][15]. As a matter of fact, Maruthamuthu et al have shown that the reactivity of hydroxyl radicals on acetate decreases considerably with increasing halogen substitution [13].…”

Section: Introductionmentioning

confidence: 78%

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On the Role of the Cathode for the Electro-Oxidation of Perfluorooctanoic Acid

et al. 2020

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Perfluorooctanoic acid (PFOA), C7F15COOH, has been widely employed over the past fifty years, causing an environmental problem because of its dispersion and low biodegradability. Furthermore, the high stability of this molecule, conferred by the high strength of the C-F bond makes it very difficult to remove. In this work, electrochemical techniques are applied for PFOA degradation in order to study the influence of the cathode on defluorination. For this purpose, boron-doped diamond (BDD), Pt, Zr, and stainless steel have been tested as cathodes working with BDD anode at low electrolyte concentration (3.5 mM) to degrade PFOA at 100 mg/L. Among these cathodic materials, Pt improves the defluorination reaction. The electro-degradation of a PFOA molecule starts by a direct exchange of one electron at the anode and then follows a complex mechanism involving reaction with hydroxyl radicals and adsorbed hydrogen on the cathode. It is assumed that Pt acts as an electrocatalyst, enhancing PFOA defluorination by the reduction reaction of perfluorinated carbonyl intermediates on the cathode. The defluorinated intermediates are then more easily oxidized by HO• radicals. Hence, high mineralization (xTOC: 76.1%) and defluorination degrees (xF−: 58.6%) were reached with Pt working at current density j = 7.9 mA/cm2. This BDD-Pt system reaches a higher efficiency in terms of defluorination for a given electrical charge than previous works reported in literature. Influence of the electrolyte composition and initial pH are also explored.

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Section: Hso + Ho • → So • + H Omentioning

confidence: 83%

Section: Introductionmentioning

confidence: 78%

On the Role of the Cathode for the Electro-Oxidation of Perfluorooctanoic Acid

et al. 2020

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“…In addition to mineralization of around 86% and nearly 100% defluorination for 20 mg/L PFOA in a 22 h experiment, the report highlights the synergistic effect of hydroxyl radicals and aqueous electrons, which are both necessary to achieve efficient removal. Indeed, hydroxyl radical-based processes such as Fenton, photo-Fenton, and hydrogen peroxide activation are ineffective due to the inactivity of OH • , as also recently clarified by Javed et al [136], who found no significant difference in PFOA degradation under UV irradiation and UV/H 2 O 2 . In contrast, several processes based on sulfate radicals (SO 4…”

Section: Methods Based On a Sacrificial Radical Sourcementioning

confidence: 89%

Light-Induced Advanced Oxidation Processes as PFAS Remediation Methods: A Review

et al. 2021

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PFAS substances, which have been under investigation in recent years, are certainly some of the most critical emerging contaminants. Their presence in drinking water, correlated with diseases, is consistently being confirmed by scientific studies in the academic and health sectors. With the aim of developing new technologies to mitigate the water contamination problem, research activity based on advanced oxidation processes for PFAS dealkylation and subsequent mineralization is active. While UV radiation could be directly employed for decontamination, there are nevertheless considerable problems regarding its use, even from a large-scale perspective. In contrast, the use of cheap, robust, and green photocatalytic materials active under near UV-visible radiation shows interesting prospects. In this paper we take stock of the health problems related to PFAS, and then provide an update on strategies based on the use of photocatalysts and the latest findings regarding reaction mechanisms. Finally, we detail some brief considerations in relation to the economic aspects of possible solutions.

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“…However, in the past decade, increasing toxicologic a l researches have shown that PFOS is related to epigenetic changes, developmenta l toxicity, immunotoxicity, hepatotoxicity, and endocrine disruption [5,8,9]. Additionally, because of the high bonding energy of C-F bond (485 kJ/mol) and strong electronegativity of fluorine (4.0), PFOS is extremely resistant to hydrolysis, pyrolys is, photolysis and biological degradation, which makes it highly persistent in the environment [2].With an oxidation potential higher than +2.0 V (vs. NHE) and a reduction potential lower than -1.3 V [10], PFOS is difficult to be effective ly decomposed by conventional water treatment technologies [11,12].…”

Section: Introductionmentioning

confidence: 99%