Electrochemical reduction of some saturated and unsaturated perfluorocarbons

Pud, A. A.; Шаповал, Г. С.; Kukhar, V. P.; Mikulina, O. E.; Gervits, L. L.

doi:10.1016/0013-4686(95)00030-i

Cited by 29 publications

(30 citation statements)

References 11 publications

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“…Unsaturated per-and poly-fluoroorganics (i.e., those containing aromatic, benzylic, olefinic, and tertiary functional groups) will readily reductively defluorinate [176][177][178][179][180][181]. Fluoroorganics containing only secondary and primary C-F bonds are difficult to defluorinate due to low reduction potentials (E < -2.7 V) [182,183]. Only the aqueous electron and elemental alkali and alkaline metals have lower standard reduction potentials.…”

Section: Pfox Reductionmentioning

confidence: 98%

Treatment technologies for aqueous perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA)

Vecitis

Park

Cheng

et al. 2009

Front. Environ. Sci. Eng. China

376

256

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Fluorochemicals (FCs) are oxidatively recalcitrant, environmentally persistent, and resistant to most conventional treatment technologies. FCs have unique physiochemical properties derived from fluorine which is the most electronegative element. Perfluorooctanesulfonate (PFOS), and perfluorooctanoate (PFOA) have been detected globally in the hydrosphere, atmosphere and biosphere. Reducing treatment technologies such as reverses osmosis, nano-filtration and activated carbon can remove FCs from water. However, incineration of the concentrated waste is required for complete FC destruction. Recently, a number of alternative technologies for FC decomposition have been reported. The FC degradation technologies span a wide range of chemical processes including direct photolysis, photocatalytic oxidation, photochemical oxidation, photochemical reduction, thermally-induced reduction, and sonochemical pyrolysis. This paper reviews these FC degradation technologies in terms of kinetics, mechanism, energetic cost, and applicability. The optimal PFOS/PFOA treatment method is strongly dependent upon the FC concentration, background organic and metal concentration, and available degradation time.

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Section: Pfox Reductionmentioning

confidence: 98%

Treatment technologies for aqueous perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA)

Vecitis

Park

Cheng

et al. 2009

Front. Environ. Sci. Eng. China

376

256

View full text Add to dashboard Cite

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“…For example, Guan et al oxidized PFOA at a boron-doped diamond (BDD) electrode at +2.54 V. 39 Carter and Farrell oxidized PFOS using a rotating disk BDD electrode at an applied potential of +3.2 V. 40 In the case of PFC reduction, polytetrafluoroethylene (PTFE) was reported to be reduced at <-1.5 V, 41 while linear PFCs, n-C 6 F 14 and n-C 8 F 18 , were reduced at -2.4 V and -2.36 V, respectively. 42 The unsaturated and/or branched PFCs are more readily reduced than their saturated, linear counterparts. This is consistent with the observed lower reduction potentials (i.e., values range from -0.16 to -1.36 V) for perfluoroolefins.…”

Section: Pfc Cyclic Voltammetrymentioning

confidence: 99%

“…This is consistent with the observed lower reduction potentials (i.e., values range from -0.16 to -1.36 V) for perfluoroolefins. 42 Combellas et al 43 investigated the effects of the carbon tail on the electrochemical reduction potentials of C4, C6, and C8 perfluoroalkylphenylcyanides, which clustered around E = -1.3 V, indicating no significant tail-length effects. Thus, the higher current yields observed during the electrochemical reduction of PFOS are likely due to further reduction of defluorinated intermediates.…”

Section: Pfc Cyclic Voltammetrymentioning

confidence: 99%

Reductive degradation of perfluoroalkyl compounds with aquated electrons generated from iodide photolysis at 254 nm

Park

Vecitis

Cheng

et al. 2011

Photochem Photobiol Sci

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The perfluoroalkyl compounds (PFCs), perfluoroalkyl sulfonates (PFXS) and perfluoroalkyl carboxylates (PFXA) are environmentally persistent and recalcitrant towards most conventional water treatment technologies. Here, we complete an in depth examination of the UV-254 nm production of aquated electrons during iodide photolysis for the reductive defluorination of six aquated perfluoroalkyl compounds (PFCs) of various headgroup and perfluorocarbon tail length. Cyclic voltammograms (CV) show that a potential of +2.0 V (vs. NHE) is required to induce PFC oxidation and -1.0 V is required to induce PFC reduction indicating that PFC reduction is the thermodynamically preferred process. However, PFCs are observed to degrade faster during UV(254 nm)/persulfate (S 2 O 8 2-) photolysis yielding sulfate radicals (E • = +2.4 V) as compared to UV(254 nm)/iodide (I -) photolysis yielding aquated electrons (E • = -2.9 V). Aquated electron scavenging by photoproduced triiodide (I 3 -), which achieved a steady-state concentration proportional to [PFOS] 0 , reduces the efficacy of the UV/iodide system towards PFC degradation. PFC photoreduction kinetics are observed to be dependent on PFC headgroup, perfluorocarbon chain length, initial PFC concentration, and iodide concentration. From 2 to 12, pH had no observable effect on PFC photoreduction kinetics, suggesting that the aquated electron was the predominant reductant with negligible contribution from the H-atom. A large number of gaseous fluorocarbon intermediates were semi-quantitatively identified and determined to account for~25% of the initial PFOS carbon and fluorine. Reaction mechanisms that are consistent with kinetic observations are discussed.

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“…66,67 Another method of fluorination using porous carbon anodes was developed by Phillips Petroleum. 68,69 In this version, a melt comprising KF-2HF at about 100 ºC is employed, and the feed is introduced into the body of the porous electrode structure where it permeates to the electrode/electrolyte interface to be fluorinated. Fluorination is believed to occur via fluorine radicals.…”

Section: Perfluorinated Productsmentioning

confidence: 99%

Electrochemical routes for industrial synthesis

Sequeira¹,

Santos²

2009

J. Braz. Chem. Soc.

118

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Esta revisão examina as razões que justificam um interesse crescente da indústria química pelos processos eletrolíticos. Reveem-se as indústrias químicas, nas quais compostos orgânicos e inorgânicos são processados e descrevem-se os avanços tecnológicos mais relevantes. Inicialmente, abordam-se processos bem estabelecidos, como as indústrias cloroalcalinas de produção de alumínio, p-aminofenol, adiponitrila, etileno glicol, antraquinona, produtos perfluorados, ácido glioxílico e L-cisteína. Face à grande quantidade de informação disponível, o assunto é tratado com base científica, mas de modo bastante simplificado. Posteriormente, descrevem-se processos orgânicos e inorgânicos emergentes, nomeadamente processos eletroquímicos mediados e síntese em líquidos iónicos. Estabelecem-se paralelos entre síntese química e síntese eletroquímica. Estimula-se o interesse nos processos de eletrossíntese, particularmente em líquidos iónicos, não desmerecendo a importância das vias puramente químicas de síntese orgânica e inorgânica.This review examines the reasons for increasing interest towards electrolyses by the chemical industry, reviews the electrochemical industries as most of them now exist, and provides a status report on the key technological advances which are occurring to meet present and future needs. Classical industries like those of chloroalkali, aluminium, p-aminophenol, adiponitrile, ethylene glycol, anthraquinone, perfluorinated products, glyoxylic acid and L-cysteine are initially covered. Considering the large amount of available publications in these topics of electrochemical engineering, the covered relevant information is treated at a scientific level, although in a simplified way. Then the paper deals with emerging inorganic and organic processes, e.g. electrosynthesis in ionic liquids and mediated electrochemical processes, and finishes by assessing what the future development trend might be given the electrochemical and non electrochemical competing influences. With this approach it is hoped to stimulate the interest of chemical engineers and scientists non-specialised in electrochemical routes, and to review some cutting edge research, particularly as far as electrosynthesis in ionic liquids is concerned.

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Electrochemical reduction of some saturated and unsaturated perfluorocarbons

Cited by 29 publications

References 11 publications

Treatment technologies for aqueous perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA)

Treatment technologies for aqueous perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA)

Reductive degradation of perfluoroalkyl compounds with aquated electrons generated from iodide photolysis at 254 nm

Electrochemical routes for industrial synthesis

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