Thermal desorption as a high removal remediation technique for soils contaminated with per- and polyfluoroalkyl substances (PFASs)

Soils contaminated with per- and polyfluoroalkyl substances (PFASs) are an important source for impacting drinking water delivery systems and surface water bodies world-wide, posing an urgent risk to human health and environmental quality. However, few treatment techniques have been tested for PFAS-contaminated soil hotspots. This study investigated the possibility of thermal desorption as a possible technique to remediate soils contaminated with multiple PFASs. Two fortified soils ( n-ary sumation (9)PFAS approximate to 4 mg kg(-1)) and one field-contaminated soil ( n-ary sumation (9)PFAS approximate to 0.025 mg kg(-1)) were subjected to a 75-min thermal treatment at temperatures ranging from 150 to 550 degrees C. Soil concentrations of PFASs showed a significant decrease at 350 degrees C, with the n-ary sumation (9)PFAS concentration decreasing by, on average, 43% and 79% in the fortified and field contaminated soils, respectively. At 450 degrees C, >99% of PFASs were removed from the fortified soils, while at 550 degrees C the fraction removed ranged between 71 and 99% for the field contaminated soil. In the field contaminated soil, PFAS classes with functional groups of sulfonates (PFSAs) and sulfonamides (FOSAs) showed higher removal than the perfluoroalkyl carboxylates (PFCAs). Thus thermal desorption has the potential to remove a wide variety of PFASs from soil, although more studies are needed to investigate the cost-effectiveness, creation of transformation products, and air-phase vacuum filtration techniques.