Green synthesis of a modified supported cerium-based MOF for simultaneous adsorption of F⁻ and PFAS from water: Nanobubble-enhanced adsorption process and mechanism

Industrial wastewater streams laden with fluoride ions (F⁻) and per- and polyfluoroalkyl substances (PFAS) represent a serious threat to global aquatic environmental security. Metal–organic frameworks (MOFs) are among the most promising adsorbent materials for water pollution control. Nevertheless, the application of current MOF is constrained by limitations: the simultaneous and efficient capture of both F⁻ and PFAS, as well as environmentally unfriendly synthesis routes. In this study, a cerium-based MOF (Ce-M) with high F⁻ adsorption efficiency was synthesized via a green and rapid method. The Ce-M was then loaded onto a sponge and surface-modified with silane to obtain a modified supported cerium-based MOF (Ce-M@D-sponge) capable of efficient simultaneous adsorption of F⁻ and PFAS. Ce-M@D-sponge achieved removal efficiencies of over 96% for PFAS with C₆ ∼ C₈ chain lengths, over 85% for PFAS (C₄), and over 89% for F⁻. The Ce-M component and the DTSACL-modified layer component of Ce-M@D-sponge delivered adsorption capacities for F⁻ and PFAS, respectively, that surpassed those of most adsorbents reported in the literature.An enhanced adsorption process was further developed by coupling Ce-M@D-sponge with nanobubbles (NBs). The presence of NBs did not affect F⁻ removal, but increased the adsorption capacity of Ce-M@D-sponge for six typical PFAS (C₄ ∼ C₈) by 45%–88% and enhanced the adsorption rate by 15% ∼ 49%, compared to the system without NBs. Finally, the adsorption mechanisms of F⁻ and PFAS in this process were investigated.