Photochemical decomposition of environmentally persistent short-chain perfluorocarboxylic acids in water mediated by iron(II)/(III) redox reactions

Chemosphere ◽  
2007 ◽  
Vol 68 (3) ◽  
pp. 572-578 ◽  
Author(s):  
Hisao Hori ◽  
Ari Yamamoto ◽  
Kazuhide Koike ◽  
Shuzo Kutsuna ◽  
Issey Osaka ◽  
...  
Keyword(s):  
Redox Reactions ◽  
Short Chain ◽  
Perfluorocarboxylic Acids ◽  
Photochemical Decomposition

THE PHOTOCHEMICAL DECOMPOSITION OF METHYL AZIDE

1963 ◽  
Vol 41 (6) ◽  
pp. 1552-1559 ◽  
Author(s):  
C. L. Currie ◽  
B. deB. Darwent
Keyword(s):  
Quantum Yield ◽  
Vapor Phase ◽  
Gaseous Product ◽  
Short Chain ◽  
Excited Species ◽  
Photochemical Decomposition

The photolysis of methyl azide has been investigated in the vapor phase at low conversions and over suitable ranges of pressure, temperature, intensity, and wavelength. Under all conditions the principal gaseous product was N2 with small amounts of H2 (5–11%), and traces of CH4, C2H4, and C2H6. A condensate identified as (CH3N)x was also found.The quantum yield for the production of N2 is approximately 2, independent of intensity (over a 45-fold range), temperature (17–100 °C), and pressure (14–300 mm Hg). The quantum yield decreases slightly with increasing wavelength. Experiments with added CO2, CH3N2CH3, and C2H4 indicate the presence of a short chain carried mainly by the CH3N radical. Excited species probably play some role in the reaction.

Experimental and theoretical insights into the photochemical decomposition of environmentally persistent perfluorocarboxylic acids

2016 ◽  
Vol 104 ◽  
pp. 34-43 ◽  
Author(s):  
Ruijuan Qu ◽  
Jiaoqin Liu ◽  
Chenguang Li ◽  
Liansheng Wang ◽  
Zunyao Wang ◽  
...  
Keyword(s):  
Perfluorocarboxylic Acids ◽  
Photochemical Decomposition

scholarly journals Dependency of the photocatalytic and photochemical decomposition of per- and polyfluoroalkyl substances (PFAS) on their chain lengths, functional groups, and structural properties

2021 ◽  
Author(s):  
Nusrat Chowdhury ◽  
Srinivas Prabakar ◽  
Hyeok Choi
Keyword(s):  
Structural Properties ◽  
Functional Groups ◽  
Reactive Species ◽  
Short Chain ◽  
Photocatalytic Decomposition ◽  
Photochemical Decomposition ◽  
Hexafluoropropylene Oxide ◽  
Polyfluoroalkyl Substances ◽  
Chain Lengths ◽  
Long Chain

Abstract This study reports the removal of per- and polyfluoroalkyl substances (PFAS) in water using various photocatalytic and photochemical processes. PFAS were chosen, based on chain lengths, functional groups, and structural properties: 4 perfluorocarboxylic acids (PFCAs) including perfluorooctanoic acid (PFOA), 3 perfluorosulfonic acids (PFSAs) including perfluorooctanesulfonic acid (PFOS), hexafluoropropylene oxide dimer (GenX), and 6:2 fluorotelomer sulfonate (6:2 FTS), and investigated dependency of the photocatalytic decomposition of PFAS on their properties. Oxidants and reductants were introduced to study the photochemical decomposition of PFAS, and reactive species and reaction byproducts were identified to elucidate the decomposition mechanism of PFAS. Some notable findings include long chain PFCAs (95% in 48 h) and 6:2 FTS (100%) were removed via chemical decomposition in TiO2/UVC while GenX (37%), long chain PFSAs (60%), short chain PFSAs (0–10%) and short chain PFCAs (5–18%) were removed via physical adsorption. Sulfate radicals generated with persulfate (PS) played an important role in decomposing PFCAs (60–90%). Sulfite activated by UVC worked for defluorination of PFOA (75%) and PFOS (80%). PFOA was removed faster by UVC/sulfite > UVC/TiO2/sulfite ≈ UVC/TiO2/PS ≥ UVC/PS > UVC/TiO2 while PFOS was removed faster by UVC/sulfite ≫ UVC/TiO2/sulfite ≈ UVC/TiO2/PS ≈ UVC/TiO2 ≫ UVC/PS. Susceptibility of PFAS to the chemical reactions could be explained with their properties and the reactive species produced in each system.

scholarly journals Hydrated-electron-based short chain perfluorosulfonic acid decomposition in VUV/sulfite system

2020 ◽  
Vol 20 (8) ◽  
pp. 3615-3624
Author(s):  
Yurong Gu ◽  
Zijun Dong ◽  
Xi Zhang ◽  
Qi Han ◽  
Yongbing Li
Keyword(s):  
Hydrated Electron ◽  
Short Chain ◽  
Organic Substances ◽  
Acid Decomposition ◽  
Solution Ph ◽  
High Chemical ◽  
Perfluorocarboxylic Acids ◽  
Perfluoroalkyl Radical ◽  
Photo Decomposition ◽  
High Chemical Stability

Abstract Perfluorosulfonic acids (PFSAs) have attracted increasing attention due to their global distribution, high chemical stability and persistence. As a powerful reductant, hydrated electron () shows extraordinary reactivity towards halogenated organic substances like PFSAs. In this study, -based photo-decomposition of perfluorohexane sulfonate (PFHxS) in a VUV/sulfite system was investigated. The kobs of PFHxS decomposition in the studied system was 0.0049 ± 0.0005 min−1, which was 24.5-fold faster than that in a sole VUV system. It was demonstrated that was the main reactive species responsible for PFHxS decomposition. PFHxS decomposition kinetics were accelerated at higher initial solution pH and sulfite dosage, but were restrained when higher initial PFHxS concentration was introduced. Co-existence of chloride showed slight enhancement of PFHxS decomposition, whereas nitrate and bicarbonate suppressed PFHxS decomposition. Accompanying PFHxS decomposition, short chain perfluorocarboxylic acids (PFCAs) were detected as main intermediate products. PFHxS decomposition started with C-S bond fracture, followed by perfluoroalkyl radical hydrolysis reactions and perfluorohexanoic acid (PFHxA) formation. Afterwards, PFHxA was defluorinated by stepwise loss of CF2 units to generate other short chain PFCAs.

Redox Reactions in Lipid Membranes as a Model for Primordial Energy-Conserving Systems

1997 ◽  
Vol 161 ◽  
pp. 437-442
Author(s):  
Salvatore Di Bernardo ◽  
Romana Fato ◽  
Giorgio Lenaz
Keyword(s):  
Experimental Evidence ◽  
Lipid Membranes ◽  
Energy Supply ◽  
Redox Reactions ◽  
Living Systems ◽  
Asymmetric Distribution ◽  
Conservation Of Energy ◽  
Asymmetrical Distribution ◽  
Energy Conserving ◽  
Living Organisms

AbstractOne of the peculiar aspects of living systems is the production and conservation of energy. This aspect is provided by specialized organelles, such as the mitochondria and chloroplasts, in developed living organisms. In primordial systems lacking specialized enzymatic complexes the energy supply was probably bound to the generation and maintenance of an asymmetric distribution of charged molecules in compartmentalized systems. On the basis of experimental evidence, we suggest that lipophilic quinones were involved in the generation of this asymmetrical distribution of charges through vectorial redox reactions across lipid membranes.

Effect of short-chain fatty acids on the ethylene pathway in embryonic axes of Cicer arietinum during germination

1994 ◽  
Vol 92 (4) ◽  
pp. 629-635 ◽  
Author(s):  
Mercedes Gallardo ◽  
Paloma Munoz De Rueda ◽  
Angel Jesus Matilla ◽  
Isabel Maria Sanchez-Calle
Keyword(s):  
Fatty Acids ◽  
Cicer Arietinum ◽  
Short Chain Fatty Acids ◽  
Short Chain ◽  
Embryonic Axes ◽  
Chain Fatty Acids
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