Robust ZIF-8/RGO composite PU foam with mechanical and chemical durability for high-capacity oil absorption, emulsion separation, and solar-thermal conversion

Oil spills and oily wastewater pose severe threats to marine ecosystems and public health, necessitating the development of materials capable of high-performance and durable separation. Herein, a dopamine-based three-in-one strategy was employed to form a zeolitic imidazolate framework-8 (ZIF-8)/reduced graphene oxide (RGO) nanocoating in situ on the surface of polyurethane (ZRP) foam, thereby synthesizing a composite foam with a layered structure. The ZRP foam exhibits excellent hydrophobic/oleophilic properties, with an adsorption capacity for organic solvents as high as 98.76 g/g. Under gravity, the foam achieves an oil-water separation efficiency of 99.2% while effectively repelling water. For surfactant-stabilized water-in-oil emulsions, the compressed ZRP foam shows a separation efficiency of 99.8% and a flux of 664 L·m −2 ·h −1 . The material retains over 97% of its initial absorption capacity after 100 adsorption-desorption cycles and maintains structural and functional stability under harsh chemical (pH 5–14), thermal (−30 °C to 100 °C), and mechanical (compression, torsion, abrasion) conditions. Furthermore, the ZRP foam demonstrates remarkable photothermal conversion capability, which significantly reduces the viscosity of heavy oils under illumination and thereby enhances separation efficiency, including solar-assisted recovery of crude oil. This study offers a robust and sustainable strategy for oil-water separation and environmental remediation in oilfields.