Rapid PFAS removal from water with floating polymer assisted by air bubbles

This study explores using a microporous polymer synthesized through high internal phase emulsion templating (polyHIPEs) with the assistance of air bubbles for the rapid removal of per- and polyfluoroalkyl substances (PFAS) from water. PFAS gravitate towards air/water interfaces due to their hydrophobic tail and hydrophilic end group. Because of this principle, air bubbles can be used to facilitate PFAS transport and concentrate them in a foam layer on the water's surface. Due to the sponge-like structure of the polyHIPEs, these polymers also float to the water's surface. Thus, using the polyHIPEs as an adsorbent assisted by air bubbles to facilitate PFAS transport to the surface, was investigated as a method for PFAS removal from water. We found that the addition of bubbles significantly increased the removal rates for every PFAS measured. With airflow at 1 L/min, the polyHIPE captured >96 % of 10 out of 12 PFAS measured and 84 % of the total PFAS in only 10 min. Comparatively, with no airflow the polyHIPEs only captured 12 % of the total PFAS in 10 min. Adding bubbles dramatically improved the capture of short chain (≤6 carbons) PFAS. With bubbles, the polyHIPE captured 72 % of the short chain PFAS in 10 min, while without bubbles the polyHIPE had captured <1 % of the short chain PFAS in the same time. This method performed exceptionally well with a variety of interferents, including humic acid and salts, and has remarkably high adsorption capacities for several PFAS, including a capacity of 1438 mg/g for perfluorooctane sulfonic acid (PFOS).