Our recent findings indicate effective electrochemical oxidative degradation of poly- and perfluoroalkyl substances (PFASs) in water using novel titanium suboxide based porous ceramics as anodes. Pseudo first-order reaction rate constant for PFOS removal was 0.153 min-1 using 5 mA/cm2 of submerged electrode. The efficiency is significantly higher than previous studies that used Boron Doped Diamond electrodes (0.13 min-1 using 20 mA/cm2). This provides a potentially promising technology to treat PFASs in legacy AFFF stockpiles or in wastewater and contaminated groundwater. Further studies are being conducted to examine the efficiency of PFAS degradation in relation to various water and electrochemical operation conditions. The degradation of perfluoroalkyl acids (PFAAs) is evaluated individually and in mixture under an optimized condition, and the rate constant is correlated to the molecular and electronic structures of the chemicals. The mechanisms of PFAA degradation is further probed using various free radical scavengers, voltammetry and spectroscopic analyses. In addition, the influence of constituents commonly present in natural water and co-contaminants in polluted groundwater on the electrochemical oxidation process is also assessed using laboratory spiked samples and real groundwater from contaminated sites. The results are interpreted based on understanding of the PFAS degradation mechanisms obtained in this study. The energy consumption and the current efficiency of the electrochemical oxidation process is also systematically evaluated under various conditions, including reactive electrochemical membrane operations with titanium suboxide ceramics used as both the anode and a membrane in cross-flow filtration mode. The results of the study will further the understanding of PFAS degradation and mineralization in titanium suboxide based anodic oxidation, and provide a basis for process optimization, design and scaling.

Mechanisms of electrochemical oxidative degredation of poly- and perfluoralkyl substances by porous titanium suboxide anodes

256th National Meeting (2018)

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