Perfluorooctanoic acids (PFOAs) are one of the most widely known polyfluoroalkyl water pollutants. In view of their hazardous health effects, PFOAs have arisen a great deal of environmental concern, mobilizing the public opinion to demand for proper regulation. As a response, perfluoro-2-propoxypropanoic acid (C6HF11O3), commercially known as GenX, was introduced as a sustainable replacement for PFOAs. However, GenX is highly persistent under natural conditions and thus accumulate in water bodies. Furthermore, recent studies have revealed that GenX displays similar toxic effects as other PFOAs. Accordingly, there is an urgent need to develop energy-efficient treatment technologies for these hazardous pollutants. In this work, GenX was efficiently degraded by electro-Fenton (EF), a popular electrochemical advanced oxidation process that has been applied to degrade a great number of emerging pollutants. Graphene-coated Ni-foam (GcNi-F) was used as the cathode for the electrochemical H2O2 production during EF, while the anode was boron-doped diamond (BDD), which is capable of producing surface OH radicals. Remarkably, GenX was completely degraded in 180 min at 16 mA cm-2, achieving up to 92% of mineralization in 6 h with a k = 0.0175 min-1 (Fig. 1). GenX was degraded/mineralized by the synergistic effects between electron transfer reactions on the BDD surface through formation of several by-products. The results demonstrate the great potential of EF with BDD as a cutting-edge technology for the treatment of GenX and other PFASs, a major water challenge for sustainable development.

Efficient treatment of the polyfluorinated pollutant GenX by electro-Fenton paired to boron doped diamon oxidation: synergy and mechanisms

ACS Fall 2021

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