Enhanced use of foam fractionation in the photodegradation of perfluorooctane sulfonate (PFOS)

[Display omitted] •Foam fractionation can utilize surface activity of PFOS to enrich PFOS.•The photodegradation of PFOS was accelerated in the foam fractionation experiments.•Foam fractionation can provide a cheap and simple upgrade to photodegradation system. Photodegradation of perfluorooctane sulfonate (PFOS) by UV irradiation could remove this environmentally persistent chemical from aqueous solution, but its efficiency needs to be further optimized. This study introduced foam fractionation technique, which utilizing the surface activity of PFOS, to promote the removal efficiency of PFOS during photodegradation. Under the favorable conditions of foam fractionation (pH = 11.0; the height to diameter ratio of the reaction solution = 3:1; gas flow rate = 1.0 L/min) in a cylindrical glass reactor, PFOS photodegradation rate (20 mg/L initial concentration) was 8.76 times higher than that without foam fractionation, over a 3-hour reaction. While under neutral condition, PFOS photodegradation rate also experienced an increase of 7.43, 6.20 and 2.66 times compared to that without foam fractionation for initial concentrations of 20 mg/L, 5 mg/L and 1 mg/L, respectively. This combination of foam fractionation and photodegradation process will hopefully be used for treatment of PFOS and other per- and polyfluoroalkyl substances with surface activity and photodegradability.