Citation:

Kim, Y., M. Evich, AND J. Washington. Extraction Efficiency and Partitioning of Fluorotelomer Alcohols in Soils. SETAC North America 44th Annual Meeting, Louisville, KY, November 12 - 16, 2023.

Impact/Purpose:

This poster furthers the knowledge of the presence and persistence of volatile PFAS in industrially contaminated soils.  Identifying the factors involved in PFAS sorption is important in understanding and predicting a mechanism for migration of these contaminants following real-world exposure.

Description:

Fluorotelomer alcohols (FTOHs) are widely used in applications of fluorochemical manufacturing. FTOHs are precursor compounds of perfluorinated carboxylic acids such as perfluorooctanoic acid (PFOA). Since FTOHs are volatile and sparingly water soluble, liquid extraction with organic solvent is recommended. Although FTOHs are extractable with organic solvent, differing hydro- and lipophobicity with carbon chain length of FTOHs requires assessment of soil/solvent ratio or serial extraction. In this study, FTOHs in contaminated or sludge applied soils are extracted with various volumes of methyl tert-butyl ether (MTBE), and partitioning characteristic between MTBE and soil was investigated. FTOHs in soil were extracted with soil/MTBE (mass/volume; g/mL) ratio of 5/2, 1/3, 1/10, and 1/20 overnight by rotation at room temperature. To find out the extraction efficiency, soil samples were extracted serially up to 4 times. Positive chemical ionization gas chromatography mass spectrometry (GC-MS) was used for quantitation of 4:2 to 18:2 FTOHs and 5:2 to 11:2 secondary FTOHs (sFTOHs). The extracted mass of FTOHs generally increased with increasing MTBE volume. In a series of 4 serial extractions, more than 90% of the total recovery for longer chain FTOHs (10:2 to 18:2 FTOHs) was observed in the first extraction step and the total extracted mass varied relatively little across a range of soil/MTBE ratios. Conversely, the extraction efficiency of shorter chain FTOHs (4:2, 6:2, and 8:2 FTOHs), which was <50% of total FTOH mass recovered, increased with MTBE volume. Shorter chain FTOHs have less hydrophobicity and higher affinity to absorb to the soil phase relative to MTBE. In the environment, these different partitioning properties of varying chain length might affect sorbed-water partitioning and leaching in soil. The result of extracted FTOHs mass with soil depth profile will be helpful to elucidate transport of FTOHs in soil and groundwater systems.

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