Similar to CGF, kapok fiber (KF) is also a natural fiber with hollow lumen without convolutions. Owing to its hydrophobic surface and comparable oil absorbency with synthetic polymers, KF has received increasing attention as an alternative for the development of green and biodegradable oil absorbents. In this study, the improvement in the oil absorbency with PFOTES treatment was also evidenced by kapok fiber. Fig. S6 (Supporting information) shows that when KF was treated with PFOTES for 1 s, the resulting PFOTES-KF exhibited also an enhanced oil absorbency, with the increase percentage of 11.0% for soybean oil, 63.9% for engine oil and 18.5% for kerosene, respectively. Compared with PFOTES- CGF, the differences in the increase percentage are not so large between low-viscosity kerosene and high-viscosity soybean/ engine oil. This fact may be correlated with the variation in surface morphologies after PFOTES treatment, nano-scaled particles vs grooves and ridges for PFOTES-CGF and PFOTES-KF. It seems that compared with smooth surface of raw fibers, hierarchical micro/ nano-structured surface is more beneficial for retention of lowviscosity kerosene. After 10 absorption-collection cycles, the oil absorbency of PFOTES-KF can reach as high as 54.0 g/g in spite of a decrease in the oil absorbency. This improvement in the oil absorbency is closely correlated to the changes in the surface morphology (Figs. 1c and d) and hydrophobic–oleophilic properties with higher water contact angle of 150° (Fig. S7). Compared with original KF, a roughen surface with grooves and ridges opens up the possibility for PFOTES-KF to absorb and remain much more oil. Nevertheless, no significant changes in FTIR spectra was found within such a short treatment time (1 s) though an element Si is detectable by an EDS system (Figs. S8 and S9, Supporting information).