hexafluoropropylene oxide
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Author(s):  
Nusrat Chowdhury ◽  
Srinivas Prabakar ◽  
Hyeok Choi

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.


Heliyon ◽  
2021 ◽  
pp. e08272
Author(s):  
Hee Joon Yoo ◽  
Min Cheol Pyo ◽  
Yoonjin Park ◽  
Bo Yong Kim ◽  
Kwang-Won Lee

2021 ◽  
Author(s):  
Huinian Liu ◽  
Wenli Hu ◽  
Xin Li ◽  
Sihui Lu ◽  
Fangwen Hu ◽  
...  

Abstract Background: Perfluoroalkyl substances (PFAS) can endanger human health through the food chain. However, the physiological mechanisms of crops exposed to PFAS are still unclear. Objectives: The physiology, phytotoxicity and accumulation of Solanaceae model crops Nicotiana benthamiana exposed to perfluorooctanoic acid (PFOA), hexafluoropropylene oxide-dimer acid (HFPO-DA) and their mixed contaminants have been studied. Results: (i) Biomass, relative electrical conductivity and catalase all decrease; (ii) Chlorophyll, peroxidase, hydrogen peroxide and malondialdehyde all increase; (iii) Superoxide dismutase and soluble sugar both increase and then decrease; (Ⅳ) The absorption and transport of K, Ca, Mg and Na are affected, particularly shoots; (V) PFOA has the highest toxicity and bioaccumulation. Conclusion: PFAS will damages the economic benefits of crops and people's health. So, its production and uses should be curtailed except for essential uses. Future direction: Substitute substances may be more harmful, so grouping strategies and evaluation framework should be established as soon as possible.


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