Developing sorbent materials for the removal of oil spills has become an attractive research topic in recent years for its impact on environmental and ecological concerns. The sorbents should be light, low cost, oil selective, environmentally friendly, mechanically robust, easily collected, and recyclable, besides having high absorption capacities. Here, magnetic carbon nanofiber (MCF) aerogels have been developed from bacterial cellulose-based nanocomposites as efficient and recyclable oil sorbents. The MCF aerogels comprise a three-dimensional (3D) interconnected structure of carbon nanofibers, with very high porosity, decorated with uniformly dispersed magnetic nanoparticles (NPs), with an Fe/Fe 3 O 4 core− shell structure. The MCF aerogels exhibit very high magnetization (>100 emu g −1 ), compared to other previously reported magnetic aerogels, due to the Fe core/Fe 3 O 4 shell NPs, but additionally with an ultralow density of only ∼7 mg cm −3 . Furthermore, the MCF aerogel is highly compressible up to 90% strain and instantly returns to the original shape after release without any plastic deformation. It is also highly durable, up to 100 compressive stress−strain cycles. As for oil sorbents, the MCF aerogel can absorb oils directly without any postsurface treatment, due to its hydrophobic/oleophilic property. The absorption capacities are in the range of 37−87 g g −1 for various types of oils and organic solvents. These values are comparably large among magnetic carbon aerogels. Additionally, due to their large magnetization, the MCF aerogels can be easily manipulated during oil absorption and collected via external magnetic fields, which is beneficial for avoiding direct contact with possible hazardous solvents. They can then be recycled several times by dissolution with hardly any reduction in absorption capacity. This work has demonstrated that environmentally friendly biomass-derived MCF aerogels could be candidates for the absorption and recycling of oils and organic solvents from wastewater.

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Biomass-based carbon aerogels have received a lot of attention as oil sorbents or oil/water separators due to their effectiveness, low cost, and vast availability of natural resources as their precursors. Magnetically functionalizing the carbon aerogel improves its reusability by magnetic recovery after oil sorption. This work fabricated magnetic carbon nanofibers (MCF) aerogels from the pyrolysis of magnetic bacterial cellulose (MBC) aerogels. The effect of the pyrolysis temperature on the phase transformation and functionalities of the MCF aerogel was investigated. The combined characterization techniques concluded that the MBC aerogel consists of the BC nanofiber matrix decorated with nonmagnetic FeC 4 H 2 O 4 and magnetic Fe 3 O 4 nanoparticles, which transformed into amorphous carbon nanofibers anchored with the α-Fe/Fe 3 O 4 core−shell structured nanoparticles after pyrolysis at 700 °C. Increasing the pyrolysis temperature to 800−900 °C led to the formation of purer amorphous carbon nanofibers, whereas the nanoparticles turned into the α-Fe/γ-Fe core−shell structure. At 1000 °C, the amorphous carbon structure is better developed and coated on the α-Fe/γ-Fe core−shell nanoparticles. The interpretation explains the results from the magnetic measurement very well and fits perfectly on the Fe−C phase diagram. Furthermore, the MCF aerogels show excellent properties as an efficient oil sorbent, such as large surface area, low density, and hydrophobic properties. Among the samples, the MCF aerogel pyrolyzed at 700 °C (MCF700) exhibits the most desirable properties while requiring the lowest pyrolysis temperature. It could adsorb various oils and organic solvents with high sorption capacity and could be recycled several times. With its magnetic attraction ability, the MCF700 could be magnetically manipulated toward oil, and it could be retrieved after use without direct human contact. These synergistic functionalities make it practically helpful for oil-spill remedies over a large-scale area.