Influence of microplastics on the photodegradation of perfluorooctane sulfonamide (FOSA).

• The adsorption capacity of FOSA by PS was the highest, similarly, PS displayed the highest adsorption capacity to PFOA. • The pH and salinity of solution can influence adsorption of FOSA and PFOA on microplastics. • The calculated adsorption energy values of FOSA and PFOA on PS are similar to the experimental adsorption constant values. • FOSA can be photodegraded and its main product is PFOA, while the presence of microplastics has little effect on the photodegradation of FOSA. PFAS (per- and polyfluoroalkyl substances) are omnipresent in the environment and their transportation and transformation have attracted increased attention. Microplastics are another potential risk substances that can serve as a carrier for ubiquitous pollutants, thus affecting the presence of PFAS in the environment. In this study, the adsorption of perfluorooctane sulfonamide (FOSA) and perfluorooctanoic acid (PFOA) on four microplastics (PE, PVC, PS, and PTFE) and their effect on the photodegradation of FOSA were studied. The adsorption capacity of FOSA by PS was the highest, in similar, PS displayed the highest adsorption capacity in the presence of PFOA. Different effects of pH and salinity on the adsorption of FOSA and PFOA were observed among different microplastics indicating inconsistent interaction mechanisms. Furthermore, FOSA could be photodegraded, with PFOA as the main product, while the presence of microplastics had a negligible effect on the degradation of this contaminant. The results indicated that microplastics could act as PFAS concentrators. Moreover, their photochemical inertias make the pollutants enriched on microplastics more resistant to degradation. [Display omitted] [ABSTRACT FROM AUTHOR]