Efficient decomposition of perfluorocarboxylic acids in aqueous solution using microwave-induced persulfate

The microwave–hydrothermal decomposition of persistent and bioaccumulative perfluorooctanoic acid (PFOA) in water with persulfate (S2O82−) at 60, 90, and 130 °C was examined to develop an effective technology for treating PFOA pollution. S2O82− is an efficient oxidant for degrading PFOA even at the room temperature of 27 °C. Higher temperature accelerates the PFOA decomposition rate, but an extremely high temperature (130 °C) will lead to the formation of significant amounts of radical oxidants that are released rapidly to consume most remaining persulfate thus causing a lower mineralization efficiency. The solution pH value is another important factor to influence the degradation rate; there is almost no PFOA decomposition reaction under alkaline conditions. The decomposition rate in acidic conditions is 1.1–7.4 times faster than in alkaline condition. Additionally, the proposed method is also effective in decomposing other PFCA species such as the C2–C7 perfluoroalkyl groups.