Magnetic choline-modified bacterial cellulose for efficient PFOS Adsorption

This study presents the development of a novel adsorbent, Fe₃O₄-incorporated choline-modified bacterial cellulose (Fe₃O₄@CBC), speciafically developped for efficient and magnetically recoverable removal of perfluorooctane sulfonate (PFOS). Bacterial cellulose (BC) was synthesized using a co-culture of Komagataeibacter saccharivorans and Acetobacter sp., which significantly enhanced cellulose production to 9.5±1.1 g L⁻¹ (n = 3), a yield markedly higher than that from the monocultures (<0.0001). The BC was first subjected to mesylation, followed by choline grafting, resulting in the formation of cationic choline-modified cellulose (CBC). The incorporation of Fe₃O₄ nanoparticles, measuring 62 nm, was undertaken to enhance adsorption and enable magnetic separation, resulting in the formation of the Fe₃O₄@CBC composite. The composite demonstrated a maximum PFOS adsorption capacity of 95 mg/g, representing a 35-fold increase compared to native BC. Additionally, Fe₃O₄@CBC exhibited enhancements of 2.5-fold and 4.2-fold relative to Fe₃O₄ and CBC, respectively. Elemental analysis (CHNS) confirmed the successful functionalization, as evidenced by an increase in sulfur content from 0% to 12.62% following mesylation, and a rise in nitrogen content from 0% to 7.83% subsequent to choline modification. This study diverges from conventional regeneration research, which typically focuses on adsorption-desorption cycles, by quantifying PFOS in regenerant solutions to directly evaluate desorption efficiency. The regeneration experiments showed that the adsorbent maintained effective performance over five cycles, with a re-adsorption capacity of 43 mg/g. This study highlights the potential of Fe₃O₄@CBC as a highly efficient, regenerable, and magnetically separable adsorbent for sustainable PFOS removal in water treatment applications.