Hydrophobic carbon nanofiber mats and sponges have emerged as highly efficient materials for oil absorption, offering advantages in selectivity, reusability, and sorption capacity compared to other absorbent materials like graphene aerogels or natural sorbents. These materials are engineered to exhibit strong hydrophobicity and oleophilicity, making them ideal for separating oil from water in spill remediation and industrial wastewater treatment. Their unique structural and surface properties enable high absorption efficiency, durability, and ease of recovery, positioning them as superior alternatives for environmental cleanup applications.

The selectivity of hydrophobic carbon nanofiber mats stems from their tailored surface chemistry and porous structure. The nanofibers are typically functionalized with hydrophobic groups such as alkyl chains or fluorinated compounds, which repel water while allowing oil to penetrate the porous network. This selectivity is quantified by the contact angle of water, often exceeding 150 degrees, indicating superhydrophobicity. In contrast, graphene aerogels, while also hydrophobic, may lack the same level of tunability in surface chemistry, and natural sorbents like cotton or wool exhibit poor selectivity due to their inherent hydrophilicity. Carbon nanofiber mats can achieve oil-water separation efficiencies above 99%, significantly outperforming untreated natural sorbents, which often absorb both oil and water indiscriminately.

Reusability is a critical factor in evaluating the practicality of oil absorbents. Carbon nanofiber mats excel in this regard due to their mechanical robustness and structural stability. Unlike natural sorbents, which degrade after a single use or require complex cleaning processes, carbon nanofiber mats can be reused multiple times through simple mechanical squeezing, centrifugation, or thermal treatment. For example, studies have demonstrated that these mats retain over 90% of their original absorption capacity even after 10 cycles of use. Graphene aerogels, while reusable, are often more brittle and prone to structural collapse under mechanical stress, limiting their lifespan. The durability of carbon nanofiber mats is attributed to their interconnected fiber network, which resists deformation and maintains porosity under repeated compression.

Sorption capacity, measured as grams of oil absorbed per gram of absorbent, is another key metric where carbon nanofiber mats outperform many alternatives. These mats typically exhibit sorption capacities ranging from 30 to 100 times their own weight, depending on the oil type and mat density. The high capacity is a result of their large surface area, typically between 500 and 1500 m²/g, and their hierarchical pore structure, which includes macro-, meso-, and micropores. Graphene aerogels, though lightweight, often have lower densities and may not achieve the same volumetric efficiency. Natural sorbents, such as straw or sawdust, have much lower capacities, usually below 10 times their weight, and suffer from slow absorption kinetics.

The fabrication of hydrophobic carbon nanofiber mats involves techniques like electrospinning followed by carbonization and surface modification. Electrospinning produces a nonwoven mat of polymer nanofibers, which are then converted to carbon fibers through high-temperature treatment in an inert atmosphere. Post-treatment methods, such as chemical vapor deposition of hydrophobic coatings, further enhance their oil affinity. This process allows precise control over fiber diameter, mat thickness, and porosity, enabling optimization for specific applications. In comparison, graphene aerogels are typically synthesized through freeze-drying or chemical reduction, which can lead to less uniform structures and higher production costs. Natural sorbents require minimal processing but lack the performance consistency of engineered materials.

Environmental and economic considerations also favor carbon nanofiber mats. Their reusability reduces waste generation compared to single-use natural sorbents, which must be disposed of after oil saturation. Additionally, the mats can be produced from renewable precursors like lignin or cellulose derivatives, aligning with sustainability goals. Graphene aerogels, while promising, often rely on expensive raw materials like graphene oxide, hindering large-scale deployment. Carbon nanofiber mats strike a balance between performance and cost, making them viable for industrial applications.

In summary, hydrophobic carbon nanofiber mats represent a superior solution for oil absorption due to their exceptional selectivity, reusability, and sorption capacity. Their engineered structure and surface properties outperform graphene aerogels in mechanical durability and natural sorbents in efficiency and longevity. As environmental regulations tighten and the demand for effective spill remediation grows, these materials are poised to play a pivotal role in sustainable oil-water separation technologies. Future research may focus on further enhancing their absorption kinetics and scalability to meet global challenges in environmental protection.