# Modified Kapok Fibers (_Ceiba pentandra_ ([PERSON]) for Oil Spill Remediation
## 3 Results and Discussion
### Discussions and Recommendations  
Some authors have treated kapok fibers with NaClO\({}_{2}\) to make them hydrophilic and used the material as a methylene blue adsorbent and obtained responses of 80 to 100 mg/g of adsorptive capacity, with the surface of the fibers interacting by hydrogen bonding with nitrogen, sulphur, and aromatic rings of the methylene blue molecules [31]. Also, acetylated kapok fibers that were used for diesel oil removal obtained an improvement from 30.5 g/g to 34 and 36.7 g/g, depending on the acetylation route [32]. The same authors observed that for soybean oil, the behavior was similar, with approximately 45 g/g removed for natural fibers and about 50 g/g for acetylated ones. The authors mentioned that acetylation can improve the homogeneity of oil distribution on the surface. Furthermore, it was identified that kapok fibers treated with water, HCl, NaOH, NaClO\({}_{2}\), and chloroform may have both an increased and unchanged sorption capacity for organic solvents [22]. All these researchers have attributed the sorption effects to the structuring and functional capacities of the materials and, when sorption increases, it is said that the material has become more oleophilic or rough, and when it decreases, it is because the fiber has suffered damage to its lumens or general structure. However, the phenomenon needs to be highlighted more forcefully, given that the results presented here lead to a more complete interpretation of the activation scenario. Figure 9: Average tensile strength for natural fibers and under treatments in the most extreme conditions tested in this work. According to previous work that tested desert rose fibers (_Adenium obesum_) in various oils, the sorption capacity is largely dependent on the viscosity and density of these oils, and roughness becomes more relevant to sorption as the oil viscosity reduces, since it will contribute more to maintaining the oil in adhesion [33]. Furthermore, in previous work, it was indicated that the defunctionalization of kapok fibers reduces only 10% of the sorption effect, suggesting that the randomness of the fibers and lumen filling are more relevant than the initial contribution of the interaction between non-polar groups and external adhesion [21]. Therefore, with the results observed here, it can be concluded that for the action of sorbent materials, a synergy between promising non-polar functional groups and morphology prone to creating microporosity is necessary. And when activating sorbents, in general, the aim is either to add functional groups necessary to promote oleophilicity and hydrophobicity, or to increase or unclog pores--when present--by opening channels or creating rougher regions. This last effect, detailed in Table 1, the increase in roughness, is specifically relevant for the sorption test in the dripping stage, i.e., it does not influence immediate adhesion in an oil-saturated medium. However, when lifting the material that was in contact with the oil, with the action of the gravitational field, friction proves to be relevant to ensure adhesion. Observing Table 1, for example, the alkali treatment, it can be seen that for mild treatments at 0.1 M, there was no defunctionalization and neither was the roughness of the material altered, even maintaining the sorption value similar to the raw material. However, for the activation at 2.0 M, the reduction in the external hydrocarbon groups and exposure of the innermost polysaccharides led to a reduction in sorption, although the roughness tripled. Thus, the effect of roughness, although relevant, will balance the functional loss at low levels only. As the damage suffered by the fiber increases, with the presence of fractures and greater hydrophilic functional exposure, roughness does not prove to be a parameter that guarantees high values of the sorption property.