# Modified Kapok Fibers (_Ceiba pentandra_ ([PERSON]) for Oil Spill Remediation
## 4 Conclusions  
This study investigated the impact of various treatments on the sorption capacity of kapok fibers for diesel oil. Heat treatments at lower temperatures (60-70 \({}^{\circ}\)C) primarily caused moisture loss, while higher temperatures (80-100 \({}^{\circ}\)C) led to the volatilization of non-polar compounds and increased the surface roughness. Acid treatments at low concentrations (0.01 M HCl) had a minimal impact, but higher concentrations (0.1-2.0 M HCl) caused significant degradation of the surface wax, reducing the sorption capacity. Alkaline treatments at low concentrations (0.01-0.1 M NaOH) preserved the maximum sorption capacity, while higher concentrations (1.0-2.0 M NaOH) induced degradation and reduced sorption. The FTIR spectra of the fibers treated at 90 and 120 \({}^{\circ}\)C show an increase at 3410 cm\({}^{-1}\), indicating free hydroxyl groups and the breaking of hydrogen bonds, increasing hydrophobicity. At 60 \({}^{\circ}\)C, this band decreases, suggesting only dehydration. Bands at 2914 and 1736 cm\({}^{-1}\) indicate the exposure of internal layers and lignin. In the acid treatment, there is an increase at 3410 and 2914 cm\({}^{-1}\), evidencing surface degradation and the exposure of cellulose. Treatments with NaOH intensify the C=O and C-O bands, exposing internal carbohydrates, especially at high concentrations, which reduces sorption. Thus, the removal of hydrocarbons and waxes resulted in greater hydrophilicity. The structural evaluation by SEM and AFM indicated a tendency for increased surface roughness when the materials were treated under more extreme conditions, and, given that defunctionalization occurred under these same conditions, it was inferred that roughness contributed to ensuring the maintenance of the original sorption, but without being the determining factor.  
Conceptualization, L.M.T.M.O. and J.L.d.S.D.; methodology, L.M.T.M.O. and J.L.d.S.D.; validation, L.M.T.M.O., J.L.d.S.D., J.N.S.R.d.O. and L.F.A.M.O.; formal analysis, L.M.T.M.O., J.L.d.S.D., E.J.S.F., C.L.P.S.Z., S.T.d.S., J.N.S.R.d.O. and L.F.A.M.O.; investigation, L.M.T.M.O., C.L.P.S.Z., J.N.S.R.d.O. and L.F.A.M.O.; resources, L.M.T.M.O., E.J.S.F. and J.L.d.S.D.; data curation, L.M.T.M.O.; writing--original draft preparation, L.M.T.M.O., V.B.B. and J.L.d.S.D.; writing--review and editing L.M.T.M.O. and J.L.d.S.D.; visualization, L.M.T.M.O., V.B.B. and J.L.d.S.D.; supervision, L.M.T.M.O. and J.L.d.S.D.; project administration, L.M.T.M.O. and J.L.d.S.D.; funding acquisition, L.M.T.M.O., C.L.P.S.Z. and J.L.d.S.D. All authors have read and agreed to the published version of the manuscript.  
This research was funded by Alagoas State Research Support Foundation (FAPEAIL/Brazil), grant number APQ2022021000095 FAPEAL call 002/2022.  
Not applicable.  
The original contributions presented in the study are included in the article; further inquiries can be directed to the corresponding author.  
The authors would like to thank the National Council for Scientific and Technological Development (CNPq/Brazil) and the Coordination for the Improvement of Higher Education Personnel (CAPES/Brazil).  
The authors declare no conflicts of interest.