Simple one-pot fabrication of durable superhydrophobic cotton wool using octadecyltrimethoxysilane modified silica-sol for oil-water separation

Abstract

A fluorine-free superhydrophobic cotton is successfully fabricated using a simple and cost-effective one-pot synthesis method, employing octadecyltrimethoxysilane (ODTMS) as a modifying silane in a silica-sol. Unlike conventional techniques that utilise coupling agents or post-synthesis curing methods to enhance coating stability, this approach eliminates the need for extra chemicals thus saving time and reducing fabrication cost. The prepared cotton demonstrates remarkable superhydrophobicity, as evidenced by a water contact angle of 159°. Additionally, it exhibits exceptional durability and stability when exposed to harsh acidic and alkaline solutions, as well as during laundering test. Moreover, the cotton displays excellent oil–water separation efficiency (>99.0 %) and maintains consistent performance throughout 20 reuse cycles, highlighting its high reusability. Furthermore, the modified cotton is highly effective for separating oil-in-water emulsions, even for highly stable emulsions, achieving separation efficiencies above 90.0 %. The fabrication process is simple and environmentally safe, offering an economical and viable solution for industries handling oily wastewater. Overall, this fluorine-free superhydrophobic cotton presents a promising and cost-effective option for various industrial applications.