Removal of PFOA (perfluorooctanoic acid) from water using supercritical carbon dioxide.

In an experimental study using a multipurpose pilot plant suitable for intensively contacting water with supercritical carbon dioxide (scCO2) it has been demonstrated that scCO2 can take up perfluorooctanoic acid (PFOA) from water to levels down to the low µg/L level in the water. The water initially contained 100 µg/L of PFOA in all experiments. PFOA has been removed from 6 L of water for more than 98.5% using supercritical CO2 (323 K, 250 bars) in semi-continuous operation (24 L/hr). After 20 mins at 250 bar more than 90% of the PFOA was removed from the water. Batch operation (at 323 K) showed that the removal percentage decreased with pressure/density: 250 bar (834 kg/m3): 93%, 150 bar(700 kg/m3): 91 %, 105 bar(416 kg/m3): 69 %. The extracted PFOA was not recovered.