Polymeric adsorbents grafted with bio-derived hydroxy-imidazole for perfluorooctanoic acid sequestration

Due to their strong bioaccumulation and environmental persistence, increasing attention is given to water contamination by perfluoroalkyl substances (PFAS), with particular focus on perfluorooctanoic acid (PFOA). Commercial materials for its sequestration, mainly activated carbons, show moderate adsorption capacities and very slow adsorption kinetics, making efficient alternatives urgently required. In this work, polymeric adsorbents functionalized with bio-derived imidazole tags were developed to cover this gap. Micrometric polyglycidyl methacrylate particles were produced via suspension polymerization and simultaneously functionalized in one pot with hydroxy-imidazole (HI) obtained from glucose. The reaction conditions for imidazole synthesis as well as the HI/monomer stoichiometric ratio were systematically investigated, to find the particle maximum adsorption capacity. Adsorption studies were performed to characterize the efficiency of these novel particles in PFOA sequestration. Their performance was found to be a strong function of the solution pH, affecting the sequestration mechanism. At pH 3, a second order adsorption behavior was demonstrated, reaching capacities higher than 1200 mgPFOA/g. Extremely high adsorption efficiency was also found at the ppb scale, with saturation capacity of 150 mgPFOA/g at 20 ppb. Finally, a kinetic study indicated the system reached adsorption equilibrium within 15 min of contact time, making these particles particularly appealing for industrial operations.