Sorption of Perfluorinated Surfactants on Sediments

Abstract

The sorption of anionic perfluorochemical (PFC) surfactants of varying chain lengths to sediments was investigated using natural sediments of varying iron oxide and organic carbon content. Three classes of PFC surfactants were evaluated for sorptive potential: perfluorocarboxylates, perfluorosulfonates, and perfluorooctyl sulfonamide acetic acids. PFC surfactant sorption was influenced by both sediment-specific and solution-specific parameters. Sediment organic carbon, rather than sediment iron oxide content, was the dominant sediment-parameter affecting sorption, indicating the importance of hydrophobic interactions. However, sorption also increased with increasing solution [Ca2+] and decreasing pH, suggesting that electrostatic interactions play a role. Perfluorocarbon chain length was the dominant structural feature influencing sorption, with each CF2 moiety contributing 0.50-0.60 log units to the measured distribution coefficients. The sulfonate moiety contributed an additional 0.23 log units to the measured distribution coefficient, when compared to carboxylate analogs. In addition, the perfluorooctyl sulfonamide acetic acids demonstrated substantially stronger sorption than perfluorooctane sulfonate (PFOS). These data should prove useful for modeling the environmental fate of this class of contaminants.

Spatiotemporal distribution and mass loadings of perfluoroalkyl substances in the Yangtze River of China

“…Partitioning of PFASs onto sediment has been found strongly correlated with sediment TOC (Ahrens et al, 2009b;Higgins and Luthy, 2006). Higgins and Luthy (2006) also found that electrostatic interactions could play a role in sorption of PFASs to sediment.…”

“…Perfluorocarbon chain length is the dominant structural feature influencing their partitioning onto sediment (Labadie and Chevreuil, 2011). Partitioning of PFASs onto sediment has been found strongly correlated with sediment TOC (Ahrens et al, 2009b;Higgins and Luthy, 2006). Higgins and Luthy (2006) also found that electrostatic interactions could play a role in sorption of PFASs to sediment.…”

Surface-associated metal catalyst enhances the sorption of perfluorooctanoic acid to multi-walled carbon nanotubes

“…It was also reported that increasing the pH value decreases the sorption of perfluorinated chemicals on sediments or MWCNTs due to electrostatic repulsion [14]. The further reduction of the adsorption capacity, especially in case of BA above pH 6-7, may also be caused by the increasing negative surface charge of the metallic catalyst.…”

Sediment–water distribution of perfluorooctane sulfonate (PFOS) in Yangtze River Estuary

“…The partitioning of PFOS between water and suspended sediment particles is crucial for understanding the transport/transform mechanism of PFOS in the environment. Previous studies indicated that PFOS could sorb strongly to sediment when the environmental parameters such as pH, ionic strength and co-solvent were suitable (Higgins and Luthy, 2006;Johnson et al, 2007;Pan et al, 2009). Hydrophobic partition, static attraction, ion-exchange and salting out effect are presumed to be important mechanisms affecting the sorption process (Higgins and Luthy, 2006;Johnson et al, 2007;Pan et al, 2009).…”