Magnetic choline-modified bacterial cellulose for efficient PFOS Adsorption

In this study, Fe₃O₄-incorporated choline-modified bacterial cellulose (Fe₃O₄@CBC) was developed as an efficient and magnetically recoverable adsorbent for perfluorooctane sulfonate (PFOS) removal. Bacterial cellulose (BC) was produced using a co-culture of the isolated strains Komagataeibacter saccharivorans (K. saccharivorans) and Acetobacter tropicalis (A. tropicalis), where co-cultivation significantly enhanced cellulose production, yielding 11.0 ± 3 g L⁻¹ (n = 3). The BC was subsequently subjected to mesylation followed by choline grafting to produce cationic choline-modified cellulose (CBC). Following that the Fe₃O₄ nanoparticles (62 nm) were incorporated to improve adsorption performance and enable magnetic separation, resulting in the Fe₃O₄@CBC composite. The Fe₃O₄@CBC composite exhibited a maximum PFOS adsorption capacity of 95 mg g⁻¹, representing a 35-fold increase compared to native BC, and enhancements of 2.5-fold and 4.2-fold relative to Fe₃O₄ and CBC, respectively. Elemental analysis (CHNS) confirmed successful functionalization of the BC, with sulfur increasing from 0% to 12.62% after mesylation and nitrogen increasing from 0% to 7.83% post-choline modification. Unlike conventional regeneration studies that primarily report adsorption-desorption cycle counts, this work additionally quantified PFOS in regenerant solutions to directly evaluate desorption efficiency. Regeneration experiments demonstrated that the adsorbent retained effective performance over five consecutive cycles, with an experimentally determined re-adsorption capacity of 43 mg g⁻¹. This study demonstrate that Fe₃O₄@CBC is a highly efficient, regenerable, and magnetically separable adsorbent, highlighting its strong potential for sustainable PFOS remediation in water treatment applications.