Adsorption. Prior to adsorption, the adsorbents were activated overnight at 120 °C under vacuum. All sorption experiments were conducted at room temperature. A PFOA stock solution (1000 mg/L) was prepared using ultrapure H2O. Adsorbent (20 mg) was added with a 20 mL PFOA solution into a screw cap vial, stirred for 72 hours and then, the solution was filtered. The filtrate was collected for NMR analysis while the filtered solids were reused for desorption. The experiments were performed in duplicate and the average values are reported.