Diffusion and partitioning of different PFAS compounds through thermoplastic polyurethane and three different PVC-EIA...

Perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorobutane sulfonic acid (PFBS), 6:2 fluorotelomer sulfonic acid (6:2 FTS), and GenX are tested for diffusion and sorption through thermoplastic polyurethane (TPU) and three ethylene interpolymer alloy (PVC-EIA) liners (EIA1, EIA2, and EIA3) with decreasing ketone ethylene ester (KEE) contents. The tests were conducted at room temperature (23 °C), 35 °C, and 50 °C. The tests show significant diffusion through the TPU as manifested by a decrease in the source concentration and an increase in the receptor concentrations of PFOA and PFOS over time, especially at higher temperatures. On the other hand, the PVC-EIA liners show excellent diffusive resistance to the PFAS compounds especially at 23 °C. At higher temperatures, the diffusion resistance of the PVC-EIA liner with the lowest KEE content, EIA3, was best at 50 °C followed by EIA1 (highest KEE content) and finally EIA2. Sorption tests showed no measurable partitioning of any of the compounds to the liners examined. Based on 535 days of diffusion testing, permeation coefficients are provided for all the compounds considered for the four liners at three temperatures. In addition, the P_g values for PFOA and PFOS are provided for a linear low density polyethylene (LLDPE) and a coextruded LLDPE - ethylene vinyl alcohol (EVOH) geomembrane based on 1246 to 1331 days of testing and are compared to those estimated for EIA1, EIA2, and EIA3.