Sequestration of oils from water using superhydrophobic silanized montmorillonite-KSF nanoclay coated polyurethane foam

Oil spills have disastrous consequences on the environment. Multifarious absorbents have been applied in oil spill remediation; however, the design of cost-effective, dependable, and environmentally benign absorbents is desirable and pressing. Here, a polyurethane foam (PF) with superhydrophobic/superoleophilic properties was fabricated by surface coating of montmorillonite (MMT) nanoclay. Initially, the hydrophobic MMT was obtained by grafting octadecyltrimethoxysilane (ODTMS) onto the surface of the nanoclay and this was then used to modify the foam via a dip-coating technique. This modification produces a superhydrophobic foam with a water contact angle reaching 153.83 ± 1.86°. The as-prepared foam demonstrates high absorption selectivity and excellent absorption capacity of 29.5–66.5 times weight gain for several organic solvents and oils. The efficiency of separation for multiple oil-water mixtures reached 99.87%. After 10 cycles of absorption-desorption studies, such superhydrophobic foam still sustained good oil absorption performance, thus exhibiting outstanding reusability and desirable regeneration for practical applications. The oil and organic solvent samples could swiftly and continuously be retrieved from the water by the modified foam. The fabrication method for the superhydrophobic PF by its modification with natural clay minerals appears to be simple, economical, and promising for expandable applications in the effective separation of oil-water mixtures.