# Modified Kapok Fibers (_Ceiba pentandra_ ([PERSON]) for Oil Spill Remediation
###### Abstract  
The search for efficient oil spill remediation techniques leads to the use of physical, chemical, and biological methods, featuring both natural and modified lipophilic materials. Kapok fibers (_Ceiba pentandra_ ([PERSON]) have been studied as a result of their unusual natural oil sorption capacity, which can be improved even further through physical or chemical treatments that augment their rugosity and alter their functional properties. Furthermore, the exact role of fiber morphology is not completely clear regarding the sorption process. Hence, this study investigated the efficacy of Kapok fibers using different treatments, based on chemical and physical approaches, and characterized using advanced techniques (FTIR, SEM, AFM), aiming to improve the understanding of application possibilities in oil contamination scenarios. The results indicate that treatments using a low thermal intensity and low concentration do not lead to variation in sorption properties nor in surface structural features. Fiber rugosity varied from 4.40 to 12.35 nm, whereas an excessive increase in roughness was observed when the material was subject to more extreme conditions, such as a temperature of 120 \({}^{\circ}\)C and high concentrations (2.0 M) of both acid or alkali, accompanied by a loss in functionality and affecting the material sorption capacity. Thus, the study provides conditions to suggest that these treatments are not necessary for this type of material when inserted into sorption processes. oil spill remediation; oil affinity; natural materials; surface roughness; biosorption +
Footnote †: journal: Applied sciences  
0000-0001-5000-0000][PERSON]. [PERSON] 0000-0002-00  
Within the physical methods, the synthesis of ultralight lipophilic materials has become a centerpiece, with aerogels [8], graphene derivatives [9], reinforced polymeric foams [10], and the production of sorption and mechanical resistance-enhancing composites [11]. Natural-source-derived materials have also featured in the literature, mainly due to their modest cost, given that they usually come from residual biomass [12], which reduces the immediate application cost to a fraction of that expected when using synthetic systems. Nevertheless, considering that the approximate amount of annual residual biomass produced worldwide solely by the agribusiness sector is around 1300 million tons [13], it is inferred that these residues are underused and up to be employed for oil remediation. A way to augment the potential of natural material and make them competitive compared to the synthetic ones, such as polyurethane and polypropylene foams and derivatives [14], is to provide functional and structural modifications to the biomass, simplifying their handling, reducing the hydrophilicity, assuring floatation stability in aqueous systems, and increasing mechanical resistance [15], which is already applied in both synthetic and natural systems. These modifications are commonly based on thermal surface treatments, e.g., pyrolysis, hydrothermal carbonization [16], controlled heating [17], hydrothermal liquefaction [18], and immersion in acid and base solutions and in organic solvents [19]. _Ceiba pentandra_ ([PERSON] [PERSON] is a tree known as paina, silk-cotton, silkfloss, or kapok tree, and produces fruit formed of an internal fibrous structure that confers protection and moisture control to the seeds [20]. Kapok fibers are composed of cellulose, lignin, and hemicellulose, and characterized by a hollow cylindrical morphology, with a surface covered by wax, which comprises a mixture of alkanes, such octane, nonane, and decane, in addition to aromatic compounds, benzene and \(\alpha\)-xylene, and a miniscule number of oxygenated compounds, mainly alcohols, making the material a highly lipophilic biomass [21].