Interaction mechanism between chlorinated polyfluoroalkyl ether potassium sulfonate (F-53B) and chromium on different types of soil surfaces.

The coexistence of per- and polyfluoroalkyl substances (PFASs) and heavy metals have been found in soils. However, the interaction between the combined pollutants in soils remains unclear. In this study, the adsorption processes of single and combined Cr(VI) and chlorinated polyfluoroalkyl ether potassium sulfonate (F-53 B) in red, yellow and black soils were simulated. When compared with the single F-53 B and Cr(VI), the adsorption amount of the combined F-53 B and Cr(VI) on soils changed with the types of soils. The interactions between F-53 B and Cr(VI) in soils affected their adsorption behavior. The adsorption of the combined F-53 B and Cr(VI) best fit second-order kinetics and the Freundlich equation. Moreover, aluminum and iron oxides are highly correlated with adsorption of F-53 B and Cr(VI). Both F-53 B and Cr(VI) can form complexes with aluminum and iron oxides through electrostatic interactions, but PFOS could be bridged with iron oxides to form an inner sphere complex and with aluminum oxides to form an outer sphere complex. The coexistence of F-53 B and Cr(VI) could change the fluorescent group of dissolved organic matter (DOM) in soils due to the complexation between F-53 B and DOM. In addition, F-53 B increased the acid-soluble portion of Cr and decreased its residual form, which promoted the environmental risk of Cr in soils.