Magnetic bacterial cellulose and carbon nanofiber aerogel by simple immersion and pyrolysis

Bacterial cellulose (BC)/Fe₃O₄ aerogels were fabricated by a simple immersion of BC hydrogels in commercially available ferrofluid solution followed by freeze-drying. The BC/Fe₃O₄ aerogels were converted into carbon nanofiber (CNF)/Fe₃O₄ aerogels by pyrolysis at 600 °C. With our fabrication methods, the Fe₃O₄ nanoparticles (NPs) were effectively impregnated and homogeneously distributed in the nanostructures of BC and CNF. The average diameters of the BC and CNF nanofibers were found to be about 79.3 ± 14.1 nm and 56.7 ± 13.6 nm, respectively. Increasing the ferrofluid concentration resulted in a nonlinear increase of Fe₃O₄ NPs loaded into the BC and CNF structure, but the functional groups were not affected. The saturation magnetization (M_s) of CNF/Fe₃O₄ was larger than those of BC/Fe₃O₄ and increased with the amount of impregnated Fe₃O₄ NPs. The maximum magnetization in our work was larger than literature values, with the highest M_s of 82.9 emu/g approaching the bulk value of Fe₃O₄. The materials presented could be used as pollutant absorbers for wastewater treatment. We have demonstrated the capability of using magnetic CNF aerogels in absorbing a common dye pollutant from water. The dye was absorbed efficiently, and the aerogels were easily magnetically removed from the solution and are reusable.