Regeneration of PFOS loaded activated carbon by hot water and subsequent aeration enrichment of PFOS from eluent

Regeneration and reuse of spent activated carbon (AC) as well as recovery of the desorbed pollutants are challenging in the application of adsorption technology. In this study, the regeneration of perfluorooctanesulfonate (PFOS)-saturated coal-based granular AC by hot water and subsequent aeration method to enrich PFOS from eluent were investigated. The regeneration time, water temperature and solid-liquid ratio affected the regeneration efficiency of PFOS treated AC. PFOS was desorbed quickly from the AC within 30 min by hot water. High water temperature (92 °C) and low solid-liquid ratio (0.5) led to the highest desorption of 36.7% in one cycle (6 h). Over 90% PFOS on the spent AC was desorbed by 92 °C hot water with the solid-liquid ratio of 0.5 after six cycles. Subsequent experiments were conducted to enrich PFOS, and aeration of the regeneration eluent achieved the enrichment factors of 50.6–62.0 for PFOS at initial PFOS concentrations of 10–100 μg/L. The concentration of PFOS in the concentrated solution was 2.2 g/L following sequential sorption, regeneration and aeration treatments when the influent PFOS concentration was 2.7 μg/L.