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Efficiency and mechanism of intermittent reductive/oxidative defluorination of PFAS by synergistic methods

  • 15 November, 2022
  • Wageningen University, Environmental Technology
  • prof.dr. H. Rijnaarts
  • dr.ir. H. Bruning

Nowadays per- and polyfluoroalkylated substances (PFAS) have caused broad attention due to their widely existence in the environment, persistence, bioaccumulation, and potential health risks. However, PFAS are highly resistant to conventional wastewater treatment due to their exceedingly stable C–F bonds. Through traditional reductive or oxidative destructive techniques, PFAS can be degraded but not be completely defluorinated, which will cause the formation of fluorine-containing by-products with even greater toxicity. The produced fluorotelomers (CnF2n+1–(CH2)m–X) show high recalcitrance against further degradation during reductive defluorination processes, and hydroxyl radical (HO•) produced during oxidative processes can convert fluorotelomers into perfluorocarboxylates (PFCAs). Based on these information, this PhD project aims to realize intermittent reductive and oxidative conditions through the combination of electrochemical, chemical and UV/VUV processes to develop new combinations of treatment technologies and find some strategies for the deep degradation and defluorination of PFAS. To achieve this reaction process, there are two kinds of combinations of treatment technologies. In the first scheme, we propose a circle of the UV/VUV/sulfite reductive process and the UV/VUV/H2O2 oxidative process, during which PFAS (including perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS)) can realize gradually degradation and defluorination. In the other scheme, based on an electrochemical system, intermittent reductive/oxidative defluorination of PFAS (including FPOA and PFOS) is achieved by the circulation through the cathode and the anode compartments.The theoretical and experimental research on different PFAS compounds will can give us new insights into the structure dependence of the degradation mechanism.

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Shuhao Liu

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