Electrochemical Oxidation of Perfluorooctanoic Acid (PFOA) from Aqueous Solution using Non-Active Ti/SnO2-Sb2O5/PbO2 Anodes

In this study, electrochemical oxidation of perfluorooctanoic acid (PFOA, C7H15CO2H) from aqueous solution was examined in terms of PFOA and total organic carbon (TOC) removal by using Ti/SnO2-Sb2O5/PbO2non-active electrodes. The effects of operating parameters: initial pH (pHo), current density (j), and electrolyte concentration (m) at different time intervals were examined. Specific energy consumption (SEC) was used to determine the process proficiency. The C-C bond between C7F15 was first cleaved and thendegraded into fluoride ions (F−) and short carbon-chain per-fluorinated carboxylic acids (PFCAs) ((∼C2−C7) such as perfluoroethanoic acid (PFEA: C2F5CO2H), perfluoropropanoic acid (PFPA: C3F7CO2H), perfluorobutanoic acid (PFBA: C4F9CO2H), perfluoropentanoic acid (PFPeA: C5F11CO2H), perfluorohexanoic acid (PFHxA: C6F13CO2H), perfluoheptanoic acid (PFHpA: C7F14CO2H). These intermediates by-products were determined using the gas chromatograph-mass spectrometry (GC/MS) analysis. The rate of PFOA decomposition was followed the pseudo-first-order kinetics. About 82%TOC and 94% PFOA removals were formed at the optimal condition of pHo = 3.58, j=168.34 Am-2, and m = 250 mgL-1 at 120 min of electrolysis with SEC = 593 kWh/kg TOC. A plausible degradation mechanism was also proposed at the optimal treatment condition.