US EPA

3856738 

Journal Article 

Effect of chemical structure on the sonochemical degradation of perfluoroalkyl and polyfluoroalkyl substances (PFASs) 

Abad Fernandez, N; Rodriguez-Freire, L; Keswani, M; Sierra-Alvarez, R 

2016 

Yes 

Environmental Science: Water Research & Technology
ISSN: 2053-1400
EISSN: 2053-1419 

Royal Society of Chemistry 

2 

6 

975-983 

English 

10.1039/c6ew00150e 

WOS:000388470100008 

Perfluoroalkyl surfactants include chemicals characterized by a fully fluorinated carbon chain (hydrophobic and oleophobic tail) bound to a hydrophilic head (a carboxyl or sulfonic group). These compounds are toxic and highly resistant to chemical/biological attack, and some are known to be bio-accumulative. This study investigates the sonochemical degradation at 500 kHz of different carboxylic and sulfonic perfluoroalkyl and polyfluoroalkyl substances (PFASs, 1.7 mM total organic fluorine) to assess the effect of chain length, functional head group, and substituents (-CH2-CH2-moiety and ether group) on the degradation rate. Under these conditions, the rates of defluorination determined for two widely used perfluoroalkyl substances, perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA), were 3.5 to 3.7 mu M F-min(-1), respectively. The degradation rate of perfluoroalkyl sulfonates decreased with the perfluorocarbon chain length as indicated by the 1.3 and 1.9-fold lower defluorination rates for perfluorohexane- and perfluorobutane sulfonate than that of PFOS. A similar trend was observed during the sonolysis of perfluoroalkyl carboxylate analogs with 6, 5 or 3 carbon atoms which had 1.1-, 1.8-, and 2.3-fold lower defluorination rates, respectively, than that of PFOA. Furthermore, perfluoroalkyl compounds appeared more amenable to sonolysis than the polyfluoroalkyl analogues with the same number of C atoms (defluorination rate of PFOS/6 : 2 fluorotelomer sulfonate approximate to 2.3). The results demonstrate that sonolysis is a promising approach to treat PFASs in aqueous streams. Furthermore, they underscore that the chemical structure of PFASs has a marked effect on the rate at which they undergo sonochemical degradation. 

Pollution Abstracts; Environment Abstracts; Aqualine Abstracts; Water Resources Abstracts; ASFA 2: Ocean Technology Policy & Non-Living Resources; Fluorine; Sulfonates; Analogs; Degradation; Molecular Structure; Pollutants; Streams; Environmental factors; Surfactants; P 2000:FRESHWATER POLLUTION; SW 0810:General; ENA 09:Land Use & Planning; AQ 00001:Water Resources and Supplies; Q2 09144:Regional studies, expeditions and data reports