PFAS removal from wastewater by in-situ formed ferric nanoparticles: Solid phase loading and removal efficiency

Abstract PFAS removal by in-situ formed ferric nanoparticles via ozonation was evaluated in this study. The tests were conducted with synthetic contaminated water prepared from the firefighting foam concentrate at PFAS concentrations of 8.33–133 µg/L, pHs of 3–7.5, and ozone bubbling times of 15–45 s. It was found the particle sizes of the in-situ formed ferric nanoparticles were affected by ferrous dose, pH value, and ozone bubbling time. The highest PFAS removal achieved was 44%, when the PFAS feed concentration was 8.33 µg/L, ferrous dose was 40 µg/L, feed pH value was 6.2 and ozone bubbling time was 45 s. The PFAS solid phase loading of the ferric nanoparticles was significantly higher than conventionally used adsorbents. The highest PFAS solid phase loading achieved was 80% when the PFAS concentration was 8.33 µg/L, pH was 3, and mass ratio of ferrous sulphate to PFAS was 1:1.7 ± 0.3. It was found that the specific area of the nanoparticles was directly related to PFAS removal and solid phase loading. It was also found that the highest PFAS and highest PFAS solid phase loading of ferric nanoparticles could not be achieved simultaneously under the tested experimental conditions.