Polyelectrolyte metallopolymer particles for efficient PFAS capture and release

Abstract

In technologies for PFAS removal, one of the biggest challenges is combining high adsorption capacity with excellent regeneration capabilities. In recent years, metallopolymer-based materials have shown promising potential in both aspects. In this work, we present two convenient ways to functionalize organic microparticles with charged, functional moieties (cobaltocenium), either through a one-pot reaction via siloxane-condensation or by straightforward ring-opening reaction of epoxides. After characterization of the novel adsorbent materials by state-of-the-art analytics to verify the successful functionalization, their performance for PFAS adsorption and regeneration was investigated. To gain insight into the adsorption mechanism, experiments were first conducted at low concentrations (20 μg L−1) and in equilibrium, showing adsorption for both materials of up to 97 % for PFOA and PFOS. Furthermore, an increase in adsorption within an ionic matrix of commercial drinking water and an adsorbent preference at different pH values was demonstrated. Analysis of the influence of the concentration indicates multilayer adsorption beyond simple ion-paring, best described by a Brunauer-Emmett-Teller mechanism. Moreover, utilizing a straightforward column setup, the total PFOA capacity is analyzed, revealing a 4–5-fold increase upon functionalization, leading to 215 mg g−1 and 296 mg g−1 PFOA adsorption. Overall, column-based adsorption experiments showed promising results at low (20 μg L−1) and medium (2.25 mg L−1) PFAS concentrations. Finally, reusability and regeneration studies further revealed an excellent desorption performance upon multiple cycles and PFAS elution of up to 88 ± 4 %.