The occurrence of poly- and perfluoroalkyl substances (PFASs) in the environment has become a crucial issue. PFASs such as perfluorooctanesulfonate (PFOS) are extremely persistent, posing challenges to treatment technologies for their degradation. Our recent finding revealed that PFOS could be oxidized at porous Ti4O7 ceramic anode, with rates greater than those at Ce-PbO2 or BDD electrodes under the same electrolytic conditions, providing a potentially promising treatment technology for PFASs. Magnéli phase Ti4O7 ceramic material was fabricated using a high-temperature sintering method, and characterization shows it having extensive interconnecting macropores with an average pore size of 2.6 μm and 21.6% porosity. The reactivity of this material toward PFOS was evaluated in a reactive electrochemical membrane (REM) system with the porous Ti4O7 ceramic material serving as both the anode and a membrane, operated in dead-end or cross-flow filtration mode. It was observed that the surface-area-normalized rate constant (kSA) of PFOS degradation ranged from 0 to 0.53 × 10-3 m s-1 with anodic potential from 2.5 to 6.3 V (vs. SSCE), with, the reaction rate was limited by the mass transfer at high anodic potential. The interfacial reaction mechanisms were investigated using voltammetric technique and characterizations of the reaction systems perturbed by different probing chemicals, in combination with modeling tools describing the molecular interactions and mass transfer behaviors at the interface. The results provide a basis to understand PFAS degradation on Ti4O7 anode under REM conditions and for process optimization and design.

Degradation of perfluorooctanesulfonate by Ti4O7 reactive electrochemical membrane

256th National Meeting (2018)

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