Biomimetic degradability of linear perfluorooctanesulfonate (L-PFOS): Degradation products and pathways. (November 2020)

• Record Type: Journal Article
• Authors: Li, Fei; Yang, Ning; Yang, Zhimin; Cao, Wei; Zhou, Zhenming; Liao, Xiaobin; Sun, Wenjie; Yuan, Baoling
• Is Part Of: Chemosphere. Volume 259(2020)
• Publication Date: 2020-11
• Subjects: Reductive decomposition -- Linear perfluorooctanesulfonate -- Ti(III)-citrate -- Vitamin B12 -- Biomimetic reduction -- Degradation pathways; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2020.127502
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: The reductive degradability and decomposition pathways of linear perfluorooctanesulfonate (L-PFOS) were investigated in a biomimetic system consisting of Ti(III)-citrate and Vitamin B12 . Biomimetic degradation of L-PFOS could well be described by a first-order exponential decay model. Accompanied by the release of fluoride ion, technical PFOS could not only be transformed to perfluorocarboxylates (PFCAs) and perfluoroalkylsulfonates (PFSAs) with perfluoroalkyl carbon chain length < C8 (thereafter referred as carbon-chain-shortened degradation products), but also be transformed to PFCAs with perfluoroalkyl carbon chain length ≥ C8 (thereafter referred as carbon-chain-lengthened degradation products). Perfluorohexanesulfonate and perfluorotetradecanoate were the most abundant carbon-chain-shortened and -lengthened degradation products of technical PFOS, respectively. Based on the various degradation products detected during biomimetic reduction of linear [1, 2, 3, 4– 13 C4 ]-PFOS, the degradation pathways of L-PFOS were proposed as follows: L-PFOS was first reduced to C8 F17 radical by cleavage of C–S bond, and then transformed to PFOA through hydrolysis. However, the carbon-chain-shortened products were not generated through the sequential chain-shortening via C8 F17 radicals and/or L-PFOS, while the carbon-chain-lengthened products were not formed via C8 F17 radicals by stepwise addition of CF2 moiety. In fact, C8 F17 radical and/or L-PFOS were further reduced to form Cn F2n+1 (n = 1, 2, 3, 4) radicals, and these radicals were chain-lengthened by stepwise addition of C4 F8 moiety and eventually transformed to various degradation products via hydrolysis (PFCAs) or combination reaction with sulfonyl hydroxide (PFSAs). All carbon-chain-lengthened chemicals were first reported as the degradation products during the decomposition of L-PFOS, while carbon-chain-shortened compounds were first identified as the biomimetic reduction products of L-PFOS. Graphical abstract: Image 1 Highlights: L-PFOS degradation can be well described by an exponential decay model Biomimetic degradation of L-PFOS to short- & long-chain perfluorinated products Perfluorinated products of L-PFOS were first detected in a biomimetic system