Complete mineralization of perfluorooctanoic acid (PFOA) by γ-irradiation in aqueous solution
Decomposition of perfluorooctanoic acid (C 7 F 15 COOH, PFOA) has been gaining increasing interests because it is a ubiquitous environmental contaminant and resistant to the most conventional treatment processes. In this work, the rapid and complete mineralization of PFOA and simultaneous defluorination were achieved by γ-ray irradiation with a 60 Co source. The degradation rate of PFOA by γ-ray irradiation would be high and a pseudo-first-order kinetic rate constant of 0.67 h −1 could be achieved in the N 2 satured condition at pH 13.0. The experimental results and quantum chemical calculation confirmed that two radicals, i.e., hydroxyl radical (·OH) and aqueous electrons (e aq − ), were responsible for the degradation of PFOA, while only either e aq − or ·OH might not be able to accomplish complete mineralization of PFOA. The synergistic effects of ·OH and e aq − involved in the cleavage of C-C and C-F bonds and therefore complete mineralization of PFOA were achieved. The intermediate products were identified and the degradation pathway was also proposed. The results of this study may offer a useful, high-efficient approach for complete mineralizing fluorochemicals and other persistent pollutants.
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