Highly efficient electrochemical degradation of perfluorooctanoic acid (PFOA) by F-doped Ti/SnO2 electrode

The novel F-doped Ti/SnO 2 electrode prepared by SnF 4 as the single-source precursor was used for electrochemical degradation of aqueous perfluorooctanoic acid (PFOA). Higher oxidation reactivity and significantly longer service life were achieved for Ti/SnO 2 –F electrode than Ti/SnO 2 – X ( X   =   Cl, Br, I, or Sb) electrode, which could decomposed over 99% of PFOA (50   mL of 100   mg   L −1 ) within 30-min electrolysis. The property of Ti/SnO 2 –F electrode and its electrooxidation mechanism were investigated by XRD, SEM–EDX, EIS, LSV, and interfacial resistance measurements. We propose that the similar ionic radii of F and O as well as strong electronegativity of F caused its electrochemical stability with high oxygen evolution potential (OEP) and smooth surface to generate weakly adsorbed OH. The preparation conditions of electrode were also optimized including F doping amount, calcination temperature, and dip coating times, which revealed the formation process of electrode. Additionally, the major mineralization product, F − , and low concentration of shorter chain perfluorocarboxylic acids (PFCAs) were detected in solution. So the reaction pathway of PFOA electrooxidation was proposed by intermediate analysis. These results demonstrate that Ti/SnO 2 –F electrode is promising for highly efficient treatment of PFOA in wastewater.