Nature-inspired foam for treating oil-polluted water with enhanced fire protection

Abstract

The depletion of petrochemical resources, coupled with the pressing issue of oil-contaminated water, necessitates a surge in the development of sustainable adsorbent materials. In this study, a superhydrophobic-flame retardant material (M-BASiP) derived from biomass was developed by using hydrophobic nano-silica from rice husk, polydimethylsiloxane, and non-halogenated flame retardant amonium polyphosphate combined with a bamboo-based polyurethane substrate through a simple dip-coating method. The incorporation of a fire retardant significantly improved the flame retardancy of the prepared foam, which is crucial for practical applications, given the high flammability of oils and solvents. The M-BASiP foam exhibited superhydrophobicity, as indicated by a water contact angle of 155°, and demonstrated a high adsorption capacity ranging from 13 to 53 g g⁻¹ for various oils and organic solvents. Notably, its adsorption performance remained (75–96%) over 10 consecutive adsorption–desorption cycles, highlighting its efficiency and reusability for practical applications. Continuous oil/solvent-water separation of M-BASiP was also conducted using a vacuum pump, yielding an oil recovery of approximately 83–87%. The outstanding separation efficiency of foam, along with it eco-friendly and energy-efficient production process, makes it as a potential solution for oily wastewater treatment.