Efficient adsorption of PFOS and F53B from chrome plating wastewater and their subsequent degradation in the regeneration process

Wastewater from chrome plating industry contains high concentrations of perfluorooctane sulfonate (PFOS) and its alternative (chlorinated polyfluorinated ether sulfonate, namely F53B). It was the first time that simultaneous removal of PFOS and F53B from the actual wastewater was investigated using a granular reactivated carbon (R-CAC) prepared from commercial coconut-based activated carbon (CAC) through one-step KOH activation. The R-CAC removed much more PFOS and F53B than CAC, and even more than the best resin and chitosan reported. Both initial adsorption rate and adsorbed amount of F53B on R-CAC were much higher than PFOS, and adsorption isotherms of PFOS and F53B were described well by the Langmuir model. The coexisting organic matters in the wastewater were able to occupy the sorption sites for PFOS and F53B, significantly influencing their adsorption on R-CAC. The spent R-CAC was effectively regenerated by a novel method, hydrothermal-activated persulfate oxidation. The adsorbed PFOS and F53B as well as co-existing organic pollutants on R-CAC were degraded by persulfate free radicals, making sorption sites become available. The best regeneration efficiency of R-CAC was 93.3% and 97.6% for PFOS and F53B, respectively. This study accomplished the highly efficient adsorption and degradation of PFOS and F53B in actual wastewater.