# Modified Kapok Fibers (_Ceiba pentandra_ ([PERSON]) for Oil Spill Remediation
## 3 Results and Discussion
### Characterization of Natural and Treated Materials
#### 3.2.1 FTIR
The spectrum for the 0.01 mol/L NaOH-treated fiber shows the heightening of the absorption peaks at 1736 and 1245 cm\({}^{-1}\) relative to the C=O and C-O groups of lignin compared to the natural material, and again, the strongest peak of spectra is already the stretch at 1050 cm\({}^{-1}\). This C-O band can originate from different moieties, such as alcohols, carboxylic acids, and esters; hence, its intensification confirms the initial exposure of the inner carbohydrates. The treatment with 0.1 mol/L of NaOH maintained the absorption peaks derived from more polar groups at near constant intensities, apart from the C-O peak at 1050 cm\({}^{-1}\). Concomitantly, the bands generated by C=O and CH\({}_{2}\) and CH\({}_{3}\), at 2914-2918 cm\({}^{-1}\) and 1736 cm\({}^{-1}\), respectively, slightly increased. The first two treatments, with low alkali concentrations, exhibited sorptive potentials compatible with the natural material, and the FTIR data indicate that this behavior might arrive from a balance between the initial exposure of lignin and cellulose, whilst keeping part of the non-polar surface in place. At 1.0 mol/L, the largest intensity of the peak at 1050 cm\({}^{-1}\) is observed, suggesting that both structural degradation and the exposure of cellulose are advanced in these fibers, which is coherent with the low sorption the material treated at this alkali concentration presented in comparison to the one treated with 0.1 M.  
For the most alkaline treatment (NaOH 2.0 mol/L), the spectrum shows strong OH (3410 cm\({}^{-1}\)) and C-O stretches (1050 cm\({}^{-1}\)), in addition to an increase in the peaks at 1736 and 1245 cm\({}^{-1}\) and accompanied by the reduction in C-H peaks, suggesting the loss of surface hydrocarbons and other non-polar chains and the uncovering and degradation of lignin. Under these conditions, the reason for the poor sorption capacity of the kapok fibers is clear; the material surface became more hydrophilic and lost or disarrayed the heterogeneity of the surface waxy compounds. The effect of the alkaline treatments on the surface of the fibers was evaluated via SEM analysis for kapok treated with NaOH 0.1 and 2.0 mol/L (Figure 6). The initial interaction mechanism between oils and sorbents is essentially governed by the electrostatic charges of the van der Waals dipole induced by organic functional groups such as CH\({}_{3}\), CH\({}_{2}\), C-C, and C=C, which appear in the form of alkanes and alkenes and aromatic compounds, and C=O, with esters, ketones, and carboxylic acids, which appear mainly in the form of surface waves of kapok fibers, turning the fibers oleophilic and highly hydrophobic. On the other hand, when the treatments consume these waves and expose the cellulose structure, they show an increase in the hydrophilicity of the material due to the presence of the various hydroxyls and C-O that make up the ligno-cellulosic molecules of biomass. These are capable of hydrogen bonding with water; therefore, there is less interaction with non-polar compounds [21, 22, 28]. Thus, FTIR indicated that under low concentrations, thermal, acid, and alkali activations merely consume moisture and some more volatile compounds and are not decisive in influencing sorption. On the other hand, when treated under more extreme conditions, such as 120 \({}^{\circ}\)C and a 2.0 M concentration for acid and alkali activations, the deterioration of the waxy structure that gives functionality and a sorbent character to the material is noted, inducing--alone--a reduction in sorption. The emphatic observation that the effect of functionalization, alone, reduces sorption is important because for some treatment concentrations, such as 1.0 M of hydrochloric acid, it was possible to observe no change in sorption behavior. This may have occurred due to the probable effect of structural counterbalancing, that is, the morphology may have been altered enough to compensate for the loss of functionalization. Figure 6: SEM micrographs of kapok fibers subject to acid treatments.