US EPA

6326944 

Journal Article 

Transformation of 6:2 Fluorotelomer Sulfonate by Cobalt(II)-Activated Peroxymonosulfate 

Zhang, Y; Liu, J; Moores, A; Ghoshal, S 

2020 

1 

Environmental Science & Technology
ISSN: 0013-936X
EISSN: 1520-5851 

American Chemical Society 

54 

7 

4631-4640 

English 

32062971 

10.1021/acs.est.9b07113 

WOS:000526418000094 

Peroxymonosulfate (PMS)-based advanced oxidation processes generate highly reactive SO4•- and are promising for water treatment. In this study, we investigated the reaction mechanism of 6:2 fluorotelomer sulfonate (6:2 FTS) with Co2+-activated PMS. 6:2 FTS was simultaneously transformed to perfluoroalkyl carboxylic acids (C2-C7 PFCAs) of different chain lengths, with perfluorohexanoic acid (C6) as the predominant one. The mass balance of the intermediates and products versus the initially added 6:2 FTS was close to 100% over the reaction period. Using chemical scavenging methods, we identified that •OH, instead of SO4•-, was the oxidant initiating the reaction of 6:2 FTS. •OH was mainly produced from SO4•- reacting with H2O. Thus, the reactivity of 6:2 FTS was controlled by the factors affecting the production and scavenging of both SO4•- and •OH. Density functional theory calculations showed that •OH oxidizes 6:2 FTS by H-abstraction from ethyl carbons. This is the first study that demonstrates that •OH in Co2+-activated PMS can play a significant role in contaminant transformations. The results indicate that great caution should be taken when PMS or other agents that generate •OH are used for the treatment of water containing 6:2 FTS or its structural analogs.