Superhydrophobically modified kapok fiber and powder: Surface characteristic, oil sorption and pore structure

As a biodegradable material with high oil adsorbing efficiency, kapok fibers have a natural large lumen with a microporous cell wall. Superhydrophobic modification was carried out to enhance its oil absorbency. Kapok fiber (KF) and kapok powder (KP) were pretreated with three different solutions and subsequently modified using methyltrichlorosilane. Results indicate that different solutions of pretreatment exerted different effects on the structure and modification efficacy. Superficial wax of kapok was removed in pretreatment along with the interstice-filled lignin and hemicellulose, which caused the generation of wrinkles and cracks. Consequently, the surface area and pore width increased to provide more sites for silane to attach. Silane nanoparticles were observed to graft onto the kapok surface after modification and they revealed a preference for NaClO2-treated surface. The modified KF and KP obtained hydrophobic surface and higher oil absorbency. Notably, NaClO2- treated KP obtained the superhydrophobic effect whereas NaClO2-treated KF acquired optimum oil adsorption capacities.