Ultralight, multifunctional and recyclable bacterial cellulose/coir fiber composite foam for oil-water separation and...

Bio-derived composite foams with lightweight, highly porous structures have attracted increasing attention for applications in biomedicine, sensing, thermal insulation, oil-water separation, and environmental remediation due to their sustainability and multifunctionality. In this work, we reported a novel composite foam (CBF), mainly composed of coir fiber, a cellulose fiber renowned for its excellent mechanical strength, durability, low density, and abundant availability as an agricultural waste. The obtained natural coir fiber-based foams owned a porous network skeleton with an ultralow density of 8.08 mg/cm³ and ultrahigh porosity of 99.28%, demonstrating low thermal conductivity (0.038 W/(m·K)), which is comparable to conventional bio-derived thermal insulation materials. After subsequent hydrophobic modification, the hydrophobic (a water contact angle of 147.4°) and oleophilic foam was capable of absorbing a variety of oils and organic solvents (60.63-164.83 g/g), showing good oil retention capacity and reusability. These results underscore the potential of the fiber-based foam as a multifunctional material for thermal management and environmental protection applications.