Possible Fluorinated Alternatives of PFOS and PFOA: Ready to Go?

By Yao Lu, Yong Liang, Zhen Zhou, Yawei Wang, and Guibin Jiang
Environ Sci Technol.
December 9, 2019
DOI: 10.1021/acs.est.9b06323

Due to the unique properties of the C−F bond, finding fluorine-free alternatives giving comparable performance is challenging based on the current technical conditions. In order to maintain the performance while simultaneously reducing the negative environmental effects of alternative compounds, including the PBT properties (persistence, bioaccumulation, and toxicity) to circumvent the regulation, certain alternative strategies for PFOS and PFOA have often been adopted. These strategies include shortening the length of the fluorocarbon chain (e.g., perfluorobutanesulfonate), introduc- ing heteroatoms into the fluorocarbon chain (e.g., HFPO-DA), and/or replacing part of the C−F bonds in the fluorocarbon with C−H bonds (e.g., 6:2 fluorotelomer sulfonate), among others. As a result, the structures of these alternatives are generally similar to those of the legacy PFASs. Nevertheless, these alternative strategies are usually under-considered regarding the potential environmental risks of the new alternatives. For example, it is generally recognized that short-chain fluorinated alternatives (C ≤ 6) are less bioaccumulative compared to the long-chain homologues; however, the short-chain structure of these alternative results in greater mobility owing to their lower molecular weight. Moreover, short-chain PFASs are usually inferior to long-chain ones in terms of performance. In order to ensure the performance, higher amounts of short-chain PFASs are needed and used by the industry, which could result in the release of more PFASs in the environment.

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